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Sample records for assembled polymer nanowires

  1. Synthesis and characterization of nanowire coils of organometallic coordination polymers for controlled cargo release.

    Science.gov (United States)

    Liang, Guodong; Ni, Huan; Bao, Suping; Zhu, Fangming; Gao, Haiyang; Wu, Qing

    2014-06-12

    Nanowire coils of organometallic coordination polymers have been synthesized for the first time by using the emulsion periphery polymerization technique. An amphiphilic triblock copolymer terminated with inclusion complex of β-cyclodextrin and 4,4'-bipyridine self-assembles into oil-in-water emulsion in a toluene/water mixture. Subsequent coordination of bipyridine with Ni(II) in periphery of emulsions results in the formation of coordination polymer nanowire coils. The nanowire coils are composed of nanowires with diameter of 2 nm. Nanowire coils exhibit enhanced thermal stability in contrast to their parent triblock copolymer. Interestingly, nanowire coils are capable of encapsulating organic cargoes. Encapsulated cargoes can be selectively extracted from nanowire coils without damaging nanowire coils. Nanowire coils are potential candidates for encapsulating and controlled release of organic cargoes. PMID:24842771

  2. Solution assembly of conjugated polymers

    Science.gov (United States)

    Bokel, Felicia A.

    This dissertation focuses on the solution-state polymer assembly of conjugated polymers with specific attention to nano- and molecular-scale morphology. Understanding how to control these structures holds potential for applications in polymer-based electronics. Optimization of conjugated polymer morphology was performed with three objectives: 1) segregation of donor and acceptor materials on the nanometer length-scale, 2) achieving molecular-scale ordering in terms of crystallinity within distinct domains, and 3) maximizing the number and quality of well-defined donor/acceptor interfaces. Chapter 1 introduces the development of a mixed solvent method to create crystalline poly(3-hexyl thiophene) (P3HT) fibrils in solution. Chapter 2 describes fibril purification and approaches to robust and functional fibrils, while chapters 3 and 4 demonstrate the formation of hybrid nanocomposite wires of P3HT and cadmium selenide (CdSe) nanoparticles by two methods: 1) co-crystallization of free and P3HT-grafted CdSe for composite nanowires and 2) direct attachment of CdSe nanoparticles at fibril edges to give superhighway structures. These composite structures show great potential in the application of optoelectronic devices, such as the active layer of solar cells. Finally, ultrafast photophysical characterization of these polymers, using time-resolved photoluminescence and transient absorption, was performed to determine the aggregation types present in suspended fibrils and monitor the formation and decay of charged species in fibrils and donor-acceptor systems.

  3. Smooth Nanowire/Polymer Composite Transparent Electrodes

    KAUST Repository

    Gaynor, Whitney

    2011-04-29

    Smooth composite transparent electrodes are fabricated via lamination of silver nanowires into the polymer poly-(4,3-ethylene dioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS). The surface roughness is dramatically reduced compared to bare nanowires. High-efficiency P3HT:PCBM organic photovoltaic cells can be fabricated using these composites, reproducing the performance of cells on indium tin oxide (ITO) on glass and improving the performance of cells on ITO on plastic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Recent Advances in Directed Assembly of Nanowires or Nanotub es

    Institute of Scientific and Technical Information of China (English)

    Mei Liu; Zhizheng Wu; Woon Ming Lau; Jun Yang

    2012-01-01

    Nanowires and nanotubes of diverse material compositions, properties and/or functions have been produced or fabricated through various bottom-up or top-down approaches. These nanowires or nanotubes have also been utilized as potential building blocks for functional nanodevices. The key for the integration of those nanowire or nanotube based devices is to assemble these one dimensional nanomaterials to specific locations using techniques that are highly controllable and scalable. Ideally such techniques should enable assembly of highly uniform nanowire/nanotube arrays with precise control of density, location, dimension or even ma-terial types of nanowires/nanotubes. Numerous assembly techniques are being developed that can quickly align and assemble large quantities of one type or multiple types of nanowires through parallel processes, in-cluding flow-assisted alignment, Langmuir-Blodgett assembly, bubble-blown technique, electric/magnetic- field directed assembly, contact/roll printing, knocking-down, etc.. With these assembling techniques, applications of nanowire/nanotube based devices such as flexible electronics and sensors have been demonstrated. This paper delivers an overall review of directed nanowire/nanotube assembling approaches and analyzes advantages and limitations of each method. The future research directions have also been discussed.

  5. Functional Nanoscale Electronic Devices Assembled Using Silicon Nanowire Building Blocks

    Science.gov (United States)

    Cui, Yi; Lieber, Charles M.

    2001-02-01

    Because semiconductor nanowires can transport electrons and holes, they could function as building blocks for nanoscale electronics assembled without the need for complex and costly fabrication facilities. Boron- and phosphorous-doped silicon nanowires were used as building blocks to assemble three types of semiconductor nanodevices. Passive diode structures consisting of crossed p- and n-type nanowires exhibit rectifying transport similar to planar p-n junctions. Active bipolar transistors, consisting of heavily and lightly n-doped nanowires crossing a common p-type wire base, exhibit common base and emitter current gains as large as 0.94 and 16, respectively. In addition, p- and n-type nanowires have been used to assemble complementary inverter-like structures. The facile assembly of key electronic device elements from well-defined nanoscale building blocks may represent a step toward a ``bottom-up'' paradigm for electronics manufacturing.

  6. Synthesis, chemical modification, and surface assembly of carbon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Amma, A.; St. Angelo, S.K.; Mallouk, T.E. [Department of Chemistry, The Pennsylvania State University, University Park, PA 16802 (United States); Razavi, B.; Mayer, T.S. [Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2003-05-01

    Carbon nanotubules and nanowires were synthesized by pyrolysis of polymer precursors in the pores of alumina membranes. The nanowires were released by dissolving the membranes, and were then made hydrophobic or hydrophilic by chemical surface derivatization. These nanowires could be placed into lithographically defined wells on surfaces by means of electrostatic interactions with monolayers at the bottoms of the wells. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  7. Polymer Directed Protein Assemblies

    NARCIS (Netherlands)

    van Rijn, Patrick

    2013-01-01

    Protein aggregation and protein self-assembly is an important occurrence in natural systems, and is in some form or other dictated by biopolymers. Very obvious influences of biopolymers on protein assemblies are, e. g., virus particles. Viruses are a multi-protein assembly of which the morphology is

  8. Simulation study of dielectrophoretic assembly of nanowire between electrode pairs

    International Nuclear Information System (INIS)

    Dielectrophoresis (DEP) of rod-shaped nanostructures is attractive because of its exceptional capability to fabricate nanowire-based electronic devices. This efficient manipulation method, however, has a common side effect of assembling a certain number of nanowires at undesired positions. It is therefore essential to understand the underlying physics of DEP of nanowires in order to better guide the assembly. In this work, we propose theoretical methods to characterize the dielectrophoretic force and torque as well as the hydrodynamic drag force and torque on the nanowire (typical length: 10 μm). The trajectory of the nanowire is then simulated based on rigid body dynamics. The nanowire is predicted to either bridge the electrodes or attach on the surface of one electrode. A neighborhood in which the nanowire is more likely to bridge electrodes is found, which is conducive to successful assembly. The simulation study in this work provides us not only a better understanding of the underlying physics but also practical guidance on nanowire assembly by DEP

  9. Simulation study of dielectrophoretic assembly of nanowire between electrode pairs

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Quan, E-mail: taq3@pitt.edu; Lan, Fei; Jiang, Minlin [University of Pittsburgh, The Department of Electrical and Computer Engineering (United States); Wei, Fanan [Chinese Academy of Sciences, State Key Laboratory of Robotics, Shenyang Institute of Automation (China); Li, Guangyong, E-mail: gul6@pitt.edu [University of Pittsburgh, The Department of Electrical and Computer Engineering (United States)

    2015-07-15

    Dielectrophoresis (DEP) of rod-shaped nanostructures is attractive because of its exceptional capability to fabricate nanowire-based electronic devices. This efficient manipulation method, however, has a common side effect of assembling a certain number of nanowires at undesired positions. It is therefore essential to understand the underlying physics of DEP of nanowires in order to better guide the assembly. In this work, we propose theoretical methods to characterize the dielectrophoretic force and torque as well as the hydrodynamic drag force and torque on the nanowire (typical length: 10 μm). The trajectory of the nanowire is then simulated based on rigid body dynamics. The nanowire is predicted to either bridge the electrodes or attach on the surface of one electrode. A neighborhood in which the nanowire is more likely to bridge electrodes is found, which is conducive to successful assembly. The simulation study in this work provides us not only a better understanding of the underlying physics but also practical guidance on nanowire assembly by DEP.

  10. Location deterministic biosensing from quantum-dot-nanowire assemblies

    OpenAIRE

    Liu, Chao; Kim, Kwanoh; Fan, D. L.

    2014-01-01

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively ...

  11. Fabrication of Si3N4 nanowire membranes: free standing disordered nanopapers and aligned nanowire assemblies

    Science.gov (United States)

    Liu, Haitao; Fang, Minghao; Huang, Zhaohui; Huang, Juntong; Liu, Yan-gai; Wu, Xiaowen

    2016-08-01

    Herein, ultralong silicon nitride nanowires were synthesized via a chemical vapor deposition method by using the low-cost quartz and silicon powder as raw materials. Simple processes were used for the fabrication of disordered and ordered nanowire membranes of pure silicon nitride nanowires. The nanowires in the disordered nanopapers are intertwined with each other to form a paper-like structure which exhibit excellent flame retardancy and mechanical properties. Fourier-transform infrared spectroscopy and thermal gravity analysis were employed to characterize the refractory performance of the disordered nanopapers. Highly ordered nanowire membranes were also assembled through a three-phase assembly approach which make the Si3N4 nanowires have potential use in textured ceramics and semiconductor field. Moreover, the surface nanowires can also be modified to be hydrophobic; this characteristic make the as-prepared nanowires have the potential to be assembled by the more effective Langmuir-Blodgett method and also make the disordered nanopapers possess a super-hydrophobic surface.

  12. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu

    2015-12-02

    © 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  13. Self-Assembled PbSe Nanowire:Perovskite Hybrids.

    Science.gov (United States)

    Yang, Zhenyu; Yassitepe, Emre; Voznyy, Oleksandr; Janmohamed, Alyf; Lan, Xinzheng; Levina, Larissa; Comin, Riccardo; Sargent, Edward H

    2015-12-01

    Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  14. Location deterministic biosensing from quantum-dot-nanowire assemblies.

    Science.gov (United States)

    Liu, Chao; Kim, Kwanoh; Fan, D L

    2014-08-25

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices. PMID:25316926

  15. Location deterministic biosensing from quantum-dot-nanowire assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chao [Materials Science and Engineering Program, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Kim, Kwanoh [Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Fan, D. L., E-mail: dfan@austin.utexas.edu [Materials Science and Engineering Program, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-08-25

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.

  16. Location deterministic biosensing from quantum-dot-nanowire assemblies

    International Nuclear Information System (INIS)

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.

  17. Substrateless Welding of Self-Assembled Silver Nanowires at Air/Water Interface.

    Science.gov (United States)

    Hu, Hang; Wang, Zhongyong; Ye, Qinxian; He, Jiaqing; Nie, Xiao; He, Gufeng; Song, Chengyi; Shang, Wen; Wu, Jianbo; Tao, Peng; Deng, Tao

    2016-08-10

    Integrating connected silver nanowire networks with flexible polymers has appeared as a popular way to prepare flexible electronics. To reduce the contact resistance and enhance the connectivity between silver nanowires, various welding techniques have been developed. Herein, rather than welding on solid supporting substrates, which often requires complicated transferring operations and also may pose damage to heat-sensitive substrates, we report an alternative approach to prepare easily transferrable conductive networks through welding of self-assembled silver nanowires at the air/water interface using plasmonic heating. The intriguing welding behavior of partially aligned silver nanowires was analyzed with combined experimental observation and theoretical modeling. The underlying water not only physically supports the assembled silver nanowires but also buffers potential overheating during the welding process, thereby enabling effective welding within a broad range of illumination power density and illumination duration. The welded networks could be directly integrated with PDMS substrates to prepare high-performance stable flexible heaters that are stretchable, bendable, and can be easily patterned to explore selective heating applications. PMID:27437907

  18. Novel fabrication method of conductive polymer nanowires for sensor applications

    DEFF Research Database (Denmark)

    Christiansen, Nikolaj Ormstrup; Andersen, Karsten Brandt; Castillo, Jaime;

    2013-01-01

    In this work we demonstrate a new, quiek and low cost fabrication of PEDOT:TsO nanowires using self-assembled peptide nanotubes as a masking material. The peptide nanotubes show a remarkably stability during reactive ion etching and can be dissolved in water afterwards. We have shown that the imp...... that the impedance of the nanowire is changing with backgating the wire, this gives promising possibility for application as a sensor....

  19. Development of self-assembling nanowires containing electronically active oligothiophenes

    Science.gov (United States)

    Tsai, Wei-Wen

    This dissertation discusses the development of conductive one-dimensional nanowires from self-assembling oligothiophene molecules. Self-assembly has been demonstrated to be a promising alternative approach towards high performance, solution processable, and low-cost organic electronics. One of the many challenges in this field is the control of supramolecular morphologies of ordered structures containing pi-conjugated moieties. This research demonstrated several successful strategies to achieve self assembly of conductive nanowires using synergistic interactions combining pi stacking and hydrogen bonding. The first approach used was to develop a hairpin-shaped sexithiophene molecule, which features two arms of the conjugated structure. The diamidocyclohexyl headgroup of this molecule successfully directs the self-assembly from hydrogen bonding among the amides, forming high-aspect-ratio one-dimensional nanowires with well-defined diameters of 3.0 +/- 0.3 nm. The molecular orientation in the nanostructures promotes formation of sexithiophene H and J aggregates that facilitate efficient charge transport. Organic field-effect transistors were fabricated to reveal improved intrinsic hole mobility from films of the nanostructures, 3.46 x 10-6 cm2V-1s-1, which is one order of magnitude higher than films cast from unassembled molecules. Bulk heterojunction solar cells were developed from this molecule and fullerenes utilizing solution-phase fabrication methods. Intimate mix of the molecule and phenyl-C61-butyric acid methyl ester creates structured interfaces for efficient exciton splitting. The charge carrier mobilities of each material are improved by self-assembly in solution and thermal-energy assisted phase separation.The photovoltaic devices achieved the highest open-circuit voltage of 0.62 V, short-circuit current of 1.79 mA/cm2, fill factor of 35%, and power conversion efficiency of 0.48%. Another strategy to one-dimensional nanowires studied here involved the

  20. Energy harvesting performance of piezoelectric ceramic and polymer nanowires

    Science.gov (United States)

    Crossley, Sam; Kar-Narayan, Sohini

    2015-08-01

    Energy harvesting from ubiquitous ambient vibrations is attractive for autonomous small-power applications and thus considerable research is focused on piezoelectric materials as they permit direct inter-conversion of mechanical and electrical energy. Nanogenerators (NGs) based on piezoelectric nanowires are particularly attractive due to their sensitivity to small-scale vibrations and may possess superior mechanical-to-electrical conversion efficiency when compared to bulk or thin-film devices of the same material. However, candidate piezoelectric nanowires have hitherto been predominantly analyzed in terms of NG output (i.e. output voltage, output current and output power density). Surprisingly, the corresponding dynamical properties of the NG, including details of how the nanowires are mechanically driven and its impact on performance, have been largely neglected. Here we investigate all realizable NG driving contexts separately involving inertial displacement, applied stress T and applied strain S, highlighting the effect of driving mechanism and frequency on NG performance in each case. We argue that, in the majority of cases, the intrinsic high resonance frequencies of piezoelectric nanowires (∼tens of MHz) present no barrier to high levels of NG performance even at frequencies far below resonance (materials properties, for comparing piezoelectric NG performance under strain-driven and stress-driven conditions respectively. These figures of merit permit, for the first time, a general comparison of piezoelectric nanowires for NG applications that takes into account the nature of the mechanical excitation. We thus investigate the energy harvesting performance of prototypical piezoelectric ceramic and polymer nanowires. We find that even though ceramic and polymer nanowires have been found, in certain cases, to have similar energy conversion efficiencies, ceramics are more promising in strain-driven NGs while polymers are more promising for stress-driven NGs

  1. Thermodynamics of the adsorption of flexible polymers on nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, Thomas, E-mail: tvogel@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Gross, Jonathan, E-mail: jonathan.gross@itp.uni-leipzig.de [Institut für Theoretische Physik and Centre for Theoretical Sciences (NTZ), Universität Leipzig, Postfach 100 920, D-04009 Leipzig (Germany); Soft Matter Systems Research Group, Center for Simulational Physics, The University of Georgia, Athens, Georgia 30602 (United States); Bachmann, Michael, E-mail: bachmann@smsyslab.org [Soft Matter Systems Research Group, Center for Simulational Physics, The University of Georgia, Athens, Georgia 30602 (United States); Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá , Mato Grosso (Brazil); Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-03-14

    Generalized-ensemble simulations enable the study of complex adsorption scenarios of a coarse-grained model polymer near an attractive nanostring, representing an ultrathin nanowire. We perform canonical and microcanonical statistical analyses to investigate structural transitions of the polymer and discuss their dependence on the temperature and on model parameters such as effective wire thickness and attraction strength. The result is a complete hyperphase diagram of the polymer phases, whose locations and stability are influenced by the effective material properties of the nanowire and the strength of the thermal fluctuations. Major structural polymer phases in the adsorbed state include compact droplets attached to or wrapping around the wire, and tubelike conformations with triangular pattern that resemble ideal boron nanotubes. The classification of the transitions is performed by microcanonical inflection-point analysis.

  2. Silver nanowire array-polymer composite as thermal interface material

    Science.gov (United States)

    Xu, Ju; Munari, Alessio; Dalton, Eric; Mathewson, Alan; Razeeb, Kafil M.

    2009-12-01

    Silver nanowire arrays embedded inside polycarbonate templates are investigated as a viable thermal interface material for electronic cooling applications. The composite shows an average thermal diffusivity value of 1.89×10-5 m2 s-1, which resulted in an intrinsic thermal conductivity of 30.3 W m-1 K-1. The nanowires' protrusion from the film surface enables it to conform to the surface roughness to make a better thermal contact. This resulted in a 61% reduction in thermal impedance when compared with blank polymer. An ˜30 nm Au film on the top of the composite was found to act as a heat spreader, reducing the thermal impedance further by 35%. A contact impedance model was employed to compare the contact impedance of aligned silver nanowire-polymer composites with that of aligned carbon nanotubes, which showed that the Young's modulus of the composite is the defining factor in the overall thermal impedance of these composites.

  3. Preparation of Ag/Cu Janus nanowires: Electrodeposition in track-etched polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, X.R. [Henan Key Laboratory of Ion Beam Bioengineering, Physical Engineering College, Zhenzhou University, Zhengzhou 450052 (China); Wang, C.M.; Fu, Q.B. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Jiao, Z.; Wang, W.D.; Qin, G.Y. [Henan Key Laboratory of Ion Beam Bioengineering, Physical Engineering College, Zhenzhou University, Zhengzhou 450052 (China); Xue, J.M., E-mail: jmxue@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China)

    2015-08-01

    Highlights: • In this paper, we introduce a simple method for preparation of Janus nanowires by electrodeposition. • Using ion-track-etched PC polymer templates and commercial PC track-etched membrane templates, Ag/Cu Janus nanowires fabricated by this method all have uniform size. No matter how the holes array in the template, regular or not, the nanowires prepared by this method have similar properties. • By controlling the etching time, the size of the nanowires could be controlled easily and special shape nanowires also can be prepared by this template. • The polymer template is very easy to dissolve thoroughly and has no damage to nanowires almost. It is suitable for the preparation of nanowires suspension. • This method also has better applicability for polymer templates and can be seen as a simple convenient method for the preparation of Ag/Cu Janus nanowires. - Abstract: Bimetal (Janus) nanowire has been widely used as a promising nanoscale motor. In this paper we present a highly controllable method to fabricate Ag/Cu Janus nanowires using track-etched polymer templates. Ag/Cu Janus nanowires with uniform size and stabilized structure have been successfully fabricated by electrodepositing Ag nanowires, and subsequently Cu nanowires in track-etched polymer templates. The pore size of nanopores prepared by this template is uniform and continuously controlled, so aperture of achieved nanowires are uniform and can be regulated. This polymer template can dissolve inorganic solvents that do not react with the nanowires, making it is easy to release the nanowires into solution. The nanopore shape in the track-etched templates is adjustable (e.g. conical), nanowires with more special shapes could be fabricated. Thus, these features make this simple and inexpensive method very suitable for the preparation of Janus nanowire.

  4. Computational design of co-assembling protein-DNA nanowires

    Science.gov (United States)

    Mou, Yun; Yu, Jiun-Yann; Wannier, Timothy M.; Guo, Chin-Lin; Mayo, Stephen L.

    2015-09-01

    Biomolecular self-assemblies are of great interest to nanotechnologists because of their functional versatility and their biocompatibility. Over the past decade, sophisticated single-component nanostructures composed exclusively of nucleic acids, peptides and proteins have been reported, and these nanostructures have been used in a wide range of applications, from drug delivery to molecular computing. Despite these successes, the development of hybrid co-assemblies of nucleic acids and proteins has remained elusive. Here we use computational protein design to create a protein-DNA co-assembling nanomaterial whose assembly is driven via non-covalent interactions. To achieve this, a homodimerization interface is engineered onto the Drosophila Engrailed homeodomain (ENH), allowing the dimerized protein complex to bind to two double-stranded DNA (dsDNA) molecules. By varying the arrangement of protein-binding sites on the dsDNA, an irregular bulk nanoparticle or a nanowire with single-molecule width can be spontaneously formed by mixing the protein and dsDNA building blocks. We characterize the protein-DNA nanowire using fluorescence microscopy, atomic force microscopy and X-ray crystallography, confirming that the nanowire is formed via the proposed mechanism. This work lays the foundation for the development of new classes of protein-DNA hybrid materials. Further applications can be explored by incorporating DNA origami, DNA aptamers and/or peptide epitopes into the protein-DNA framework presented here.

  5. Self-assembled diphenylalanine nanowires for cellular studies and sensor applications.

    Science.gov (United States)

    Sasso, Luigi; Vedarethinam, Indumathi; Emnéus, Jenny; Svendsen, Winnie E; Castillo-León, Jaime

    2012-04-01

    In this paper we present a series of experiments showing that vertical self-assembled diphenylalanine peptide nanowires (PNWs) are a suitable candidate material for cellular biosensing. We grew HeLa and PC12 cells onto PNW modified gold surfaces and observed no hindrance of cell growth caused by the peptide nanostructures; furthermore we studied the properties of PNWs by investigating their influence on the electrochemical behavior of gold electrodes. The PNWs were functionalized with polypyrrole (PPy) by chemical polymerization, therefore creating conducting peptide/polymer nanowire structures vertically attached to a metal electrode. The electroactivity of such structures was characterized by cyclic voltammetry. The PNW/PPy modified electrodes were finally used as amperometric dopamine sensors, yielding a detection limit of 3,1 microM. PMID:22849068

  6. Size dependent nanomechanics of coil spring shaped polymer nanowires

    Science.gov (United States)

    Ushiba, Shota; Masui, Kyoko; Taguchi, Natsuo; Hamano, Tomoki; Kawata, Satoshi; Shoji, Satoru

    2015-11-01

    Direct laser writing (DLW) via two-photon polymerization (TPP) has been established as a powerful technique for fabrication and integration of nanoscale components, as it enables the production of three dimensional (3D) micro/nano objects. This technique has indeed led to numerous applications, including micro- and nanoelectromechanical systems (MEMS/NEMS), metamaterials, mechanical metamaterials, and photonic crystals. However, as the feature sizes decrease, an urgent demand has emerged to uncover the mechanics of nanosized polymer materials. Here, we fabricate coil spring shaped polymer nanowires using DLW via two-photon polymerization. We find that even the nanocoil springs follow a linear-response against applied forces, following Hooke’s law, as revealed by compression tests using an atomic force microscope. Further, the elasticity of the polymer material is found to become significantly greater as the wire radius is decreased from 550 to 350 nm. Polarized Raman spectroscopy measurements show that polymer chains are aligned in nanowires along the axis, which may be responsible for the size dependence. Our findings provide insight into the nanomechanics of polymer materials fabricated by DLW, which leads to further applications based on nanosized polymer materials.

  7. Polymer Self-assembly on Carbon Nanotubes

    Science.gov (United States)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  8. Casting Metal Nanowires Within Discrete Self-Assembled Peptide Nanotubes

    Science.gov (United States)

    Reches, Meital; Gazit, Ehud

    2003-04-01

    Tubular nanostructures are suggested to have a wide range of applications in nanotechnology. We report our observation of the self-assembly of a very short peptide, the Alzheimer's β-amyloid diphenylalanine structural motif, into discrete and stiff nanotubes. Reduction of ionic silver within the nanotubes, followed by enzymatic degradation of the peptide backbone, resulted in the production of discrete nanowires with a long persistence length. The same dipeptide building block, made of D-phenylalanine, resulted in the production of enzymatically stable nanotubes.

  9. Investigation of functionalized silicon nanowires by self-assembled monolayer

    Science.gov (United States)

    Hemed, Nofar Mintz; Convertino, Annalisa; Shacham-Diamand, Yosi

    2016-03-01

    The functionalization using self assembled monolayer (SAM) of silicon nanowires (SiNW) fabricated by plasma enhanced chemical vapor deposition (PECVD) is reported here. The SAM is being utilized as the first building block in the functionalization process. The morphology of the SiNW comprises a polycrystalline core wrapped by an hydrogenated amorphous silicon (α-Si:H) shell. Since most of the available methods for SAM verification and characterization are suitable only for flat substrates; therefore, in addition to the SiNW α-Si:H on flat samples were produced in the same system as the SiNWs. First we confirmed the SAM's presence on the flat α-Si:H samples using the following methods: contact angle measurement to determine the change in surface energy; atomic force microscopy (AFM) to determine uniformity and molecular coverage. Spectroscopic ellipsometry and X-ray reflectivity (XRR) were performed to measure SAM layer thickness and density. X-ray photoelectron spectroscopy (XPS) was applied to study the chemical states of the surface. Next, SiNW/SAM were tested by electrochemical impedance spectroscopy (EIS), and the results were compared to α-Si:H/SAM. The SAM electrical coverage on SiNW and α-Si:H was found to be ∼37% and ∼65 ± 3%, respectively. A model, based on transmission line theory for the nanowires is presented to explain the disparity in results between the nanowires and flat surface of the same materials.

  10. Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

    Science.gov (United States)

    Sodano, Henry A.; Brett, Robert

    2011-01-01

    The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

  11. Assembly of CdS Nanowires from Solution Using Oriented Nanofibers

    Institute of Scientific and Technical Information of China (English)

    YAN Shan-cheng; WU Jian-sheng; TANG Li-hua

    2012-01-01

    This paper presents an universal assembly approach,based on the oriented nanofibers,for the formation of large-scale ordered nanowire arrays.First,CdS NWs solution is dripped onto the substrate surface.Second,before the CdS NWs solution evaporates,the oriented nanofibers slides along the substrate surface to assemble the CdS nanowires.The mechanism involving ordered alignment of nanowires on the substrate surface was investigated based on our experimental results.The resulting nanowires arrays can be further used for the creation of massive nanoelectronic-device arrays.

  12. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    Science.gov (United States)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  13. Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer

    OpenAIRE

    Jinzhang Liu; Nunzio Motta; Soonil Lee

    2012-01-01

    ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS), a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay ti...

  14. Functional ZnO/polymer core-shell nanowires fabricated by oxidative chemical vapour deposition

    International Nuclear Information System (INIS)

    Functional ZnO-nanowire/polymer core-shell heterostructures were realized using oxidative chemical vapour deposition (oCVD). This dry and versatile technique allows uniform coating of semiconductor nanowires with polymers and simultaneous doping control of the shell. Here, 100 nm thick, p-doped shells of poly(3,4-ethylenedioxythiophene) (PEDOT) were deposited around n-conductive ZnO nanowires. Energy-dispersive x-ray spectroscopy confirms the incorporation of Br dopants into the PEDOT shell, and the resulting p-conductivity of the polymer shell is demonstrated by electrical measurements on nanowire arrays. Photoluminescence spectroscopy points to reactions of Br with the ZnO surface but proves that the nanowires show only little degradation of their optical properties. (paper)

  15. Aligned nanowires and nanodots by directed block copolymer assembly

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shuaigang; Yang Xiaomin; Lee, Kim Y; Ver der Veerdonk, Rene J M; Kuo, David [Seagate Technology, 47010 Kato Road, Fremont, CA 94538 (United States); Russell, Thomas P, E-mail: shuaigang.xiao@seagate.com [Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003 (United States)

    2011-07-29

    The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

  16. Fabrication of nanostructure via self-assembly of nanowires within the AAO template

    Directory of Open Access Journals (Sweden)

    Brust Mathias

    2006-01-01

    Full Text Available AbstractThe novel nanostructures are fabricated by the spatial chemical modification of nanowires within the anodic aluminum oxide (AAO template. To make the nanowires better dispersion in the aqueous solution, the copper is first deposited to fill the dendrite structure at the bottom of template. During the process of self-assembly, the dithiol compound was used as the connector between the nanowires and nanoparticles by a self-assembly method. The nanostructures of the nano cigars and structure which is containing particles junction are characterized by transmission electron microscopy (TEM. These kinds of novel nanostructure will be the building blocks for nanoelectronic and nanophotonic devices.

  17. Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ben Dkhil, S., E-mail: sadok.bendekhil@gmail.com [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Bourguiga, R. [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Davenas, J. [Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Cornu, D. [Institut Europeen des Membranes, UMR CNRS 5635, Ecole Nationale superieure de Chimie, Universite de Montpellier, 1919 route de Mende, F34000 Montpellier (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. Black-Right-Pointing-Pointer We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. Black-Right-Pointing-Pointer The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. Black-Right-Pointing-Pointer We have investigated the effects of SiNWs concentration on the photovoltaic characteristics leading to the optimization of a critical SiNWs concentration. - Abstract: Hybrid thin films combining the high optical absorption of a semiconducting polymer film and the electronic properties of silicon fillers have been investigated in the perspective of the development of low cost solar cells. Bulk heterojunction photovoltaic materials based on blends of a semiconductor polymer poly(N-vinylcarbazole) (PVK) as electron donor and silicon nanowires (SiNWs) as electron acceptor have been studied. Composite PVK/SiNWs films were cast from a common solvent mixture. UV-visible spectrometry and photoluminescence of the composites have been studied as a function of the SiNWs concentration. Photoluminescence spectroscopy (PL) shows the existence of a critical SiNWs concentration of about 10 wt % for PL quenching corresponding to the most efficient charge pair separation. The photovoltaic (PV) effect has been studied under illumination. The optimum open-circuit voltage V{sub oc} and short-circuit current density J{sub sc} are obtained for 10 wt % SiNWs whereas a degradation of these parameters is observed at higher SiNWs concentrations. These results are correlated to the formation of aggregates in the composite leading to recombination of the photogenerated charge pairs competing with the dissociation mechanism.

  18. Electrical Conductivity Studies on Individual Conjugated Polymer Nanowires: Two-Probe and Four-Probe Results

    Directory of Open Access Journals (Sweden)

    Duvail JeanLuc

    2009-01-01

    Full Text Available Abstract Two- and four-probe electrical measurements on individual conjugated polymer nanowires with different diameters ranging from 20 to 190 nm have been performed to study their conductivity and nanocontact resistance. The two-probe results reveal that all the measured polymer nanowires with different diameters are semiconducting. However, the four-probe results show that the measured polymer nanowires with diameters of 190, 95–100, 35–40 and 20–25 nm are lying in the insulating, critical, metallic and insulting regimes of metal–insulator transition, respectively. The 35–40 nm nanowire displays a metal–insulator transition at around 35 K. In addition, it was found that the nanocontact resistance is in the magnitude of 104Ω at room temperature, which is comparable to the intrinsic resistance of the nanowires. These results demonstrate that four-probe electrical measurement is necessary to explore the intrinsic electronic transport properties of isolated nanowires, especially in the case of metallic nanowires, because the metallic nature of the measured nanowires may be coved by the nanocontact resistance that cannot be excluded by a two-probe technique.

  19. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  20. Self-assembly mechanism of Ni nanowires prepared with an external magnetic field.

    Science.gov (United States)

    Li, Xiaoyu; Wang, Hu; Xie, Kenan; Long, Qin; Lai, Xuefei; Liao, Li

    2015-01-01

    Nickel nanowires with a mean diameter of about 95 nm and lengths of up to 26 μm were prepared by a chemical reduction method in aqueous solution under an external magnetic field. The self-assembly mechanism was investigated in detail. The results indicate that the self-assembly process of Ni nanowires consists of three stages: nucleation and growth, ordered alignment and self-assembly, and deposition on the surface and gaps between the nickel particles. The self-assembly phenomenon occurs only when nickel particles grow to a size of about 60 nm in the reaction system. This critical size, which is proposed for the first time, is very important to comprehend the self-assembly mechanism of Ni nanowires prepared with an external magnetic field. PMID:26665084

  1. Self-assembly of semiconductor organogelator nanowires for photoinduced charge separation.

    Science.gov (United States)

    Wicklein, André; Ghosh, Suhrit; Sommer, Michael; Würthner, Frank; Thelakkat, Mukundan

    2009-05-26

    We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor-acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor-acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor-acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm(2) for the simultaneous preparation route are short circuit current J(sc) = 0.28 mA cm(-2), open circuit voltage V(OC) = 390 mV, fill factor FF = 38%, and a power conversion efficiency eta = 0.041%. PMID:19408933

  2. CO2-stimulated diversiform deformations of polymer assemblies.

    Science.gov (United States)

    Yan, Qiang; Zhao, Yue

    2013-11-01

    Use of a given physiological stimulus to delicately deform polymer assemblies is a challenging topic. Here we develop synthetic block copolymers to construct a series of CO2-sensitive self-assembled nanostructures that can simulate controllable deformations of the organelles in different ways. By controlling the CO2 stimulation levels, one can modulate the size, shape, and morphology of the polymer aggregates, which is conducive to understanding the stimuli-triggered dynamic reshaping process of polymer assemblies in aqueous solution.

  3. Generalized Redox-Responsive Assembly of Carbon-Sheathed Metallic and Semiconducting Nanowire Heterostructures.

    Science.gov (United States)

    Choi, Sinho; Kim, Jieun; Hwang, Dae Yeon; Park, Hyungmin; Ryu, Jaegeon; Kwak, Sang Kyu; Park, Soojin

    2016-02-10

    One-dimensional metallic/semiconducting materials have demonstrated as building blocks for various potential applications. Here, we report on a unique synthesis technique for redox-responsive assembled carbon-sheathed metal/semiconducting nanowire heterostructures that does not require a metal catalyst. In our approach, germanium nanowires are grown by the reduction of germanium oxide particles and subsequent self-catalytic growth during the thermal decomposition of natural gas, and simultaneously, carbon sheath layers are uniformly coated on the nanowire surface. This process is a simple, reproducible, size-controllable, and cost-effective process whereby most metal oxides can be transformed into metallic/semiconducting nanowires. Furthermore, the germanium nanowires exhibit stable chemical/thermal stability and outstanding electrochemical performance including a capacity retention of ∼96% after 1200 cycles at the 0.5-1C rate as lithium-ion battery anode. PMID:26784743

  4. Ultraviolet photodetection of flexible ZnO nanowire sheets in polydimethylsiloxane polymer

    Directory of Open Access Journals (Sweden)

    Jinzhang Liu

    2012-05-01

    Full Text Available ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS, a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV photoresponse.

  5. Directed magnetic field induced assembly of high magnetic moment cobalt nanowires

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A directed magnetic field induced assembly technique was employed to align two phase (h.c.p. + f.c.c.) cobalt nanoparticles in a mechanically robust long wire morphology. Co nanoparticles with an average size of 4.3 nm and saturation magnetization comparable to bulk cobalt were synthesized...... by borohydride reduction followed by size selection and magnetic field induced assembly. The coercivity of these nanowires was higher than their nanoparticle counterpart due to shape anisotropy. The experimental coercivity values of the nanowires were lower than the predictions of the coherent rotation, fanning...

  6. Properties of polymer light-emitting transistors with Ag-nanowire source/drain electrodes fabricated on polymer substrate

    International Nuclear Information System (INIS)

    The properties of polymer light-emitting transistors with Ag-nanowire (AgNW) source/drain electrodes fabricated on a polymer substrate are investigated. Organic field-effect transistors (OFETs) based on poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) with AgNW source/drain electrodes exhibit ambipolar characteristics. For an ambipolar F8BT OFET, yellow-green light emission is observed. The maximum external quantum efficiency is 0.6%. We demonstrate the possibility of producing flexible polymer light-emitting transistors using AgNW electrodes. - Highlights: • Fluorene-type organic field-effect transistors (OFETs) are investigated. • We use Ag-nanowire (AgNW) source/drain electrodes in the OFETs. • These OFETs exhibit ambipolar and light-emitting characteristics. • The maximum external quantum efficiency is 0.6%. • We demonstrate flexible polymer light-emitting transistors using AgNW electrodes

  7. Fabrication of Highly Ordered Polymeric Nanodot and Nanowire Arrays Templated by Supramolecular Assembly Block Copolymer Nanoporous Thin Films

    Directory of Open Access Journals (Sweden)

    Liu Xikui

    2009-01-01

    Full Text Available Abstract Realizing the vast technological potential of patternable block copolymers requires both the precise controlling of the orientation and long-range ordering, which is still a challenging topic so far. Recently, we have demonstrated that ordered nanoporous thin film can be fabricated from a simple supramolecular assembly approach. Here we will extend this approach and provide a general route to fabricate large areas of highly ordered polymeric nanodot and nanowire arrays. We revealed that under a mixture solvent annealing atmosphere, a near-defect-free nanoporous thin film over large areas can be achieved. Under the direction of interpolymer hydrogen bonding and capillary action of nanopores, this ordered porous nanotemplate can be properly filled with phenolic resin precursor, followed by curation and pyrolysis at middle temperature to remove the nanotemplate, a perfect ordered polymer nanodot arrays replication was obtained. The orientation of the supramolecular assembly thin films can be readily re-aligned parallel to the substrate upon exposure to chloroform vapor, so this facile nanotemplate replica method can be further extend to generate large areas of polymeric nanowire arrays. Thus, we achieved a successful sub-30 nm patterns nanotemplates transfer methodology for fabricating polymeric nanopattern arrays with highly ordered structure and tunable morphologies.

  8. Temperature-induced reversible self-assembly of diphenylalanine peptide and the structural transition from organogel to crystalline nanowires

    OpenAIRE

    Huang, Renliang; Wang, Yuefei; Qi, Wei; Su, Rongxin; He, Zhimin

    2014-01-01

    Controlling the self-assembly of diphenylalanine peptide (FF) into various nanoarchitectures has received great amounts of attention in recent years. Here, we report the temperature-induced reversible self-assembly of diphenylalanine peptide to microtubes, nanowires, or organogel in different solvents. We also find that the organogel in isopropanol transforms into crystalline flakes or nanowires when the temperature increases. The reversible self-assembly in polar solvents may be mainly contr...

  9. Synthesis of diphenylalanine/polyaniline core/shell conducting nanowires by peptide self-assembly.

    Science.gov (United States)

    Ryu, Jungki; Park, Chan Beum

    2009-01-01

    Breaking the mold: Self-assembled peptide nanowires were used as a template for the synthesis of hollow polyaniline (PANI) nanotubes (see scanning electron microscopy images). The thickness and the morphology of the PANI nanostructures could be controlled readily either by varying the reaction time or by applying multiple PANI coatings. PMID:19466726

  10. Fabrication and characterization of PEDOT nanowires based on self-assembled peptide nanotube lithography

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Christiansen, Nikolaj Ormstrup; Castillo, Jaime;

    2013-01-01

    In this article we demonstrate the use of self-assembled peptide nanotube structures as masking material in a rapid, mild and low cost fabrication of polymerized p-toluenesulfonate doped poly(3,4-ethylenedioxythiophene) (PEDOT:TsO) nanowire device. In this new fabrication approach the PEDOT:TsO n...

  11. Self-assembled diphenylalanine nanowires for cellular studies and sensor applications

    DEFF Research Database (Denmark)

    Sasso, Luigi; Vedarethinam, Indumathi; Emnéus, Jenny;

    2012-01-01

    In this paper we present a series of experiments showing that vertical self-assembled diphenylalanine peptide nanowires (PNWs) are a suitable candidate material for cellular biosensing. We grew HeLa and PC12 cells onto PNW modified gold surfaces and observed no hindrance of cell growth caused by ...

  12. Size related transport mechanisms in hybrid metal-polymer nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Gence, L.; Faniel, S.; Vlad, A.; Dutu, C.; Melinte, S.; Bayot, V. [DICE Lab., Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Callegari, V.; Demoustier-Champagne, S. [POLY Lab., Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2008-06-15

    Electrical transport data for hybrid metal-polypyrrole nanowires of various diameters are presented and analyzed. Measurements were performed on both multiple nanowires - embedded within polycarbonate templates - and single nanowires down to low temperature T=4 K. All samples exhibit symmetrical and linear current-voltage (I-V) characteristics at room temperature. Below 77 K, all samples with diameters above 40 nm present nonlinear I-V characteristics and a zero-current plateau at 4 K. The three-dimensional Mott variable-range-hopping model provides a complete framework for the understanding of their behavior. In contrast, the transport mechanism changes for the 40 nm nanowire samples which exhibit a power-law T -dependence of the resistance, indicative of the critical regime of disorder-induced metal-insulator transitions. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Synthesis of self-assembly BaTiO3 nanowire by sol-gel and microwave method

    International Nuclear Information System (INIS)

    Self-assembly ferroelectric BaTiO3 nanowires were fabricated using sol-gel and microwave method. The X-ray diffraction patterns show that BaTiO3 nanowires belong to the tetragonal perovskite structure. An increase in the intensity of (1 1 0) peak was observed as the annealing time increased. The shape of BaTiO3 nanowires microwave-annealed for different minutes was investigated using atomic force microscopy. It is found that nanowires of BaTiO3 annealed for 2.5 min are very clear-cut, orderly and almost uninterrupted. The height of nanowire is near to the film thickness. However, nanowires of BaTiO3 annealed for 5 min are lesser, shorter and lower, and the distances among these nanowires are wider and well-proportioned. The origin of the distinct differences due to the remotion of atoms obtained enough energy was discussed.

  14. Thermal Stability and Growth Behavior of Erbium Silicide Nanowires Self-Assembled on a Vicinal Si(001) Surface

    Institute of Scientific and Technical Information of China (English)

    DING Tao; SONG Jun-Qiang; LI Juan; CAI Qun

    2011-01-01

    Erbium silicide nanowires are self-assembled on vicinal Si(Ool) substrates after electron beam evaporation and post annealing at 63(fC In-situ scanning tunneling microscopy investigations manifest that the nanowires will successively shrink and transform into a nanoisland with annealing prolonged. Meanwhile, a structural transition from hexagonal AIB2 phase to tetragonal ThSi'2 phase is revealed with high-resolution transmission electron microscopy. It is also found that the nanowires gradually expand to embed into the substrates during the growth process, which has much influence on the shape instability of nanowires. Additionally, a multiple deposition-annealing treatment is given as a novel growth method to strengthen the controlled fabrication of nanowires.%@@ Erbium silicide nanowires are self-assembled on vicinal Si(001) substrates after electron beam evaporation and post annealing at 630℃ In-situ scanning tunneling microscopy investigations manifest that the nanowires will successively shrink and transform into a nanoisland with annealing prolonged.Meanwhile, a structural transition from hexagonal AlB phase to tetragonal ThSi phase is revealed with high-resolution transmission electron microscopy.It is also found that the nanowires gradually expand to embed into the substrates during the growth process, which has much influence on the shape instability of nanowires.Additionally, a multiple deposition- annealing treatment is given as a novel growth method to strengthen the controlled fabrication of nanowires.

  15. From coordination polymers to hierarchical self-assembled structures

    NARCIS (Netherlands)

    Yan, Y.; Keizer, de A.; Cohen Stuart, M.A.; Besseling, N.A.M.

    2011-01-01

    In this review, novel hierarchical self-assembled structures based on reversible organo-metallic supramolecular polymers are discussed. Firstly, we discuss recent advances in the field of coordination polymers, considering cases in which transition metal ions and bis- or multiligands are used to bui

  16. Zinc oxide nanowire-poly(methyl methacrylate) dielectric layers for polymer capacitive pressure sensors.

    Science.gov (United States)

    Chen, Yan-Sheng; Hsieh, Gen-Wen; Chen, Shih-Ping; Tseng, Pin-Yen; Wang, Cheng-Wei

    2015-01-14

    Polymer capacitive pressure sensors based on a dielectric composite layer of zinc oxide nanowire and poly(methyl methacrylate) show pressure sensitivity in the range of 2.63 × 10(-3) to 9.95 × 10(-3) cm(2) gf(-1). This represents an increase of capacitance change by as much as a factor of 23 over pristine polymer devices. An ultralight load of only 10 mg (corresponding to an applied pressure of ∼0.01 gf cm(-2)) can be clearly recognized, demonstrating remarkable characteristics of these nanowire-polymer capacitive pressure sensors. In addition, optical transmittance of the dielectric composite layer is approximately 90% in the visible wavelength region. Their low processing temperature, transparency, and flexible dielectric film makes them a highly promising means for flexible touching and pressure-sensing applications. PMID:25494204

  17. Wafer-Level Patterned and Aligned Polymer Nanowire/Micro- and Nanotube Arrays on any Substrate

    KAUST Repository

    Morber, Jenny Ruth

    2009-05-25

    A study was conducted to fabricate wafer-level patterned and aligned polymer nanowire (PNW), micro- and nanotube arrays (PNT), which were created by exposing the polymer material to plasma etching. The approach for producing wafer-level aligned PNWs involved a one-step inductively coupled plasma (ICP) reactive ion etching process. The polymer nanowire array was fabricated in an ICP reactive ion milling chamber with a pressure of 10mTorr. Argon (Ar), O 2, and CF4 gases were released into the chamber as etchants at flow rates of 15 sccm, 10 sccm, and 40 sccm. Inert gasses, such as Ar-form positive ions were incorporated to serve as a physical component to assist in the material degradation process. One power source (400 W) was used to generate dense plasma from the input gases, while another power source applied a voltage of approximately 600V to accelerate the plasma toward the substrate.

  18. Fabrication of PEDOT/PSS-ZnO nanowire by self-assembly method under vacuum condition

    Institute of Scientific and Technical Information of China (English)

    QI Yingqun; WANG Tiejun; HU Xiujie; CHEN Ping

    2005-01-01

    In this paper, cable-like PEDOT/PSS-ZnO nanowires are successfully fabricated under vacuum condition by self-assembly of the PEDOT/PSS-ZnO composite initially prepared via sol-gel method. Characterized by TEM and EDX, the nanowire is found to have a polycrystalline ZnO inner core that is sheathed by the PEDOT/PSS blends and the nanowire has an outer diameter of ca. 100 nm. The results also indicate that the morphology of PEDOT/PSS- ZnO nanocomposite is greatly influenced by external vacuum condition and aging time. The feasible and simple approach that we have developed provides a new strategy for the synthesis of novel one-dimensional nanocomposites.

  19. Comment on "Electrical Conductivity and Current-Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires"

    Institute of Scientific and Technical Information of China (English)

    P. Ohlckers; P. Pipinys

    2009-01-01

    @@ In "Electrical Conductivity and Current-Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires", Long et al.[1] reported the currentvoltage ( Ⅰ - Ⅴ) characteristics of individual poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires in the temperature range from 20 to 50K (Fig. 2(a)). The authors stated that at temperatures equal to 50 K and higher, the Ⅰ - Ⅴ curves were linear. With decreasing temperature the Ⅰ - Ⅴ curves gradually became nonlinear. The temperature behavior of Ⅰ - Ⅴ characteristics is not suitably explained.

  20. CONDUCTING-POLYMER NANOWIRE IMMUNOSENSOR ARRAYS FOR MICROBIAL PATHOGENS

    Science.gov (United States)

    The lack of methods for routine rapid and sensitive detection and quantification of specific pathogens has limited the amount of information available on their occurrence in drinking water and other environmental samples. The nanowire biosensor arrays developed in this study w...

  1. Polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Alicia; Calleja, M.; Dimaki, Maria;

    2004-01-01

    A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip......, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro...

  2. Nonlinear optical studies of aqueous interfaces, polymers, and nanowires

    Science.gov (United States)

    Onorato, Robert Michael

    -transfer-to-solvent band and a Langmuir adsorption model are used to determine the affinity of bromide for both the air/water and dodecanol/water interfaces in the molar concentration regime. The Gibbs free energy of adsorption for the former is determined to be -1.4 kJ/mol with a lower 90% confidence limit of -4.1 kJ/mol. For the dodecanol/water interface the data are best fit with a Gibbs free energy of +8 kJ/mol with an estimated a lower limit of -4 kJ/mol. Adsorption of ions to the air/water interface in the millimolar regime is a particularly interesting phenomenon. In Chapter 4, the affinity of sodium chloride and sodium bromide to the air/water interface is probed by UV-SHG. Both salts exhibit a strong adsorption, with free energies greater than -20 kJ/mol. Interestingly, sodium chloride exhibits a stronger affinity for the interface than does sodium iodide, which was previously studied by Poul Peterson. This is counter to both experimental and theoretical results for higher concentrations. It has been predicted that ion adsorption is dictated by strong and opposing electrostatic and entropic forces. The change in order of ion interfacial affinity can be explained by relatively small changes in these forces at different concentrations and ionic strengths. In Chapters 5 and 6, other work using nonlinear optical techniques is described. Coherent anti-Stokes Raman scattering microscopy is a promising tool for chemically selective imaging based on molecular vibrations. While CARS is currently used as a biological imaging tool, many variations are still being developed, perhaps the most important being multiplex CARS microscopy. Multiplex CARS has the advantage of comparing images based on different molecular vibrations without changing the excitation wavelengths. In Chapter 5, I demonstrate both high spectral and spatial resolution multiplex CARS imaging of polymer films using a simple scheme for chirped CARS with a spectral bandwidth of 300 cm-1. In Chapter 6, the nonlinear optical

  3. Assembly and performance of silicone polymer waveguides

    Science.gov (United States)

    Lostutter, Calob K.; Hodge, Malcolm H.; Marrapode, Thomas R.; Swatowski, Brandon W.; Weidner, W. Ken

    2016-03-01

    We report on the functionality and key performance properties of 50 μm x 50 μm flexible graded index silicone polymer waveguides. The materials show low optical propagation losses of manufacturing of polymer based optical printed wiring boards. The polymer waveguides are terminated with a passive direct fiber attach method. Fully MPO connectorized waveguide panels are realized and their optical performance properties assessed.

  4. Optical devices for ultra-compact photonic integrated circuits based on III-V/polymer nanowires

    Science.gov (United States)

    Lauvernier, D.; Garidel, S.; Zegaoui, M.; Vilcot, J. P.; Harari, J.; Magnin, V.; Decoster, D.

    2007-04-01

    We demonstrated the potential application of III-V/polymer nanowires for photonic integrated circuits in a previous paper. Hereby, we report the use of a spot size converter based on 2D reverse nanotaper structure in order to improve the coupling efficiency between the nanowire and optical fiber. A total coupling enhancement of up to a factor 60 has been measured from an 80 nm × 300 nm cross-section tip which feeds an 300 nm-side square nanowire at its both ends. Simultaneously, micro-radius bends have been fabricated to increase the circuit density; for a radius of 5 µm, the 90º bend losses were measured as low as 0.60 dB and 0.80 dB for TE and TM polarizations respectively.

  5. Development of multifunctional fiber reinforced polymer composites through ZnO nanowire arrays

    Science.gov (United States)

    Malakooti, Mohammad H.; Patterson, Brendan A.; Hwang, Hyun-Sik; Sodano, Henry A.

    2016-04-01

    Piezoelectric nanowires, in particular zinc oxide (ZnO) nanowires, have been vastly used in the fabrication of electromechanical devices to convert wasted mechanical energy into useful electrical energy. Over recent years, the growth of vertically aligned ZnO nanowires on various structural fibers has led to the development of fiber-based nanostructured energy harvesting devices. However, the development of more realistic energy harvesters that are capable of continuous power generation requires a sufficient mechanical strength to withstand typical structural loading conditions. Yet, a durable, multifunctional material system has not been developed thoroughly enough to generate electrical power without deteriorating the mechanical performance. Here, a hybrid composite energy harvester is fabricated in a hierarchical design that provides both efficient power generating capabilities while enhancing the structural properties of the fiber reinforced polymer composite. Through a simple and low-cost process, a modified aramid fabric with vertically aligned ZnO nanowires grown on the fiber surface is embedded between woven carbon fabrics, which serve as the structural reinforcement as well as the top and the bottom electrodes of the nanowire arrays. The performance of the developed multifunctional composite is characterized through direct vibration excitation and tensile strength examination.

  6. Strongly Anisotropic Thermal and Electrical Conductivities of Self-assembled Silver Nanowire Network

    OpenAIRE

    Cheng, Zhe; Han, Meng; Yuan, Pengyu; Xu, Shen; Cola, Baratunde A.; Wang, Xinwei

    2016-01-01

    Heat dissipation issues are the emerging challenges in the field of flexible electronics. Thermal management of flexible electronics creates a demand for flexible materials with highly anisotropic thermal conductivity, which work as heat spreaders to remove excess heat in the in-plane direction and as heat shields to protect human skin or device components under them from heating. This study proposes a self-assembled silver nanowire network with high thermal and electrical anisotropy with the...

  7. Self-assembled quantum dot structures in a hexagonal nanowire for quantum photonics.

    Science.gov (United States)

    Yu, Ying; Dou, Xiu-Ming; Wei, Bin; Zha, Guo-Wei; Shang, Xiang-Jun; Wang, Li; Su, Dan; Xu, Jian-Xing; Wang, Hai-Yan; Ni, Hai-Qiao; Sun, Bao-Quan; Ji, Yuan; Han, Xiao-Dong; Niu, Zhi-Chuan

    2014-05-01

    Two types of quantum nanostructures based on self-assembled GaAs quantumdots embedded into GaAs/AlGaAs hexagonal nanowire systems are reported, opening a new avenue to the fabrication of highly efficient single-photon sources, as well as the design of novel quantum optics experiments and robust quantum optoelectronic devices operating at higher temperature, which are required for practical quantum photonics applications.

  8. Self-Assembly and Horizontal Orientation Growth of VO2 Nanowires

    OpenAIRE

    Chun Cheng; Hua Guo; Abbas Amini; Kai Liu; Deyi Fu; Jian Zou; Haisheng Song

    2014-01-01

    Single-crystalline vanadium dioxide (VO2) nanostructures have attracted an intense research interest recently because of their unique single-domain metal-insulator phase transition property. Synthesis of these nanostructures in the past was limited in density, alignment, or single-crystallinity. The assembly of VO2 nanowires (NWs) is desirable for a “bottom-up” approach to the engineering of intricate structures using nanoscale building blocks. Here, we report the successful synthesis of hori...

  9. Non-resonant Mie scattering: Emergent optical properties of core-shell polymer nanowires

    Science.gov (United States)

    Khudiyev, Tural; Huseyinoglu, Ersin; Bayindir, Mehmet

    2014-04-01

    We provide the in-depth characterization of light-polymer nanowire interactions in the context of an effective Mie scattering regime associated with low refractive index materials. Properties of this regime sharply contrast with these of resonant Mie scattering, and involve the formation of strictly forward-scattered and coupling-free optical fields in the vicinity of core-shell polymer nanowires. Scattering from these optical fields is shown to be non-resonant in nature and independent from incident polarization. In order to demonstrate the potential utility of this scattering regime in one-dimensional (1D) polymeric nanostructures, we fabricate polycarbonate (PC) - polyvinylidene difluoride (PVDF) core-shell nanowires using a novel iterative thermal drawing process that yields uniform and indefinitely long core-shell nanostructures. These nanowires are successfully engineered for novel nanophotonics applications, including size-dependent structural coloration, efficient light capture on thin-film solar cells, optical nano-sensors with ultrahigh sensitivity and a mask-free photolithography method suitable for the straightforward production of 1D nanopatterns.

  10. Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors

    Science.gov (United States)

    Lei, Yanlian; Deng, Ping; Li, Jun; Lin, Ming; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Ong, Beng S.

    2016-04-01

    Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm2V‑1s‑1), on/off ratio (107), and other desirable field-effect properties that meet impactful OFET application requirements.

  11. Self-Assembled DNA Templated Nano-wires and Circuits

    Science.gov (United States)

    Braun, Erez

    2000-03-01

    The realization that conventional microelectronics is approaching its miniaturization limits has motivated the search for an alternative route based on self-assembled nanometer-scale electronics. We have recently proposed a new approach based on the hybridization of biological and electronic materials (Braun E., Eichen Y., Sivan U. and Ben-Yoseph G., Nature 391, 775 (1998)). The concept relies on a two-step self-assembly process. The inherent molecular recognition capabilities of DNA molecules are first utilized to construct a network that serves as a template for the subsequent assembly of electronic materials into a circuit. The utilization of DNA and its associated enzymatic machinery enables: (a) self-assembly of complex substrates, (b) specific molecular addresses for the localization of electronic materials (e.g., gold colloids) by standard molecular biology techniques, (c) interdevice wiring and (d) bridging the microscopic structures to the macroscopic world. The self-assembly of nanometer scale electronics relies on two complementary developments. First, the ability to convert DNA molecules into thin conductive wires and second, the self-assembly of complex extended DNA templates. Our progress in these two directions will be presented. Regarding the first issue, a physical process resulting in condensation of gold colloids onto DNA molecules enables the assembly of thin gold wires (around 100-200 A wide) having, in principle, unlimited extensions. The second issue is developed in the context of recombinant DNA which allows the self-assembly of precise molecular junctions and networks. Specifically, we use RecA protein, which is the main protein responsible for genetic recombination in E. Coli bacteria, to construct DNA junctions at pre-designed addresses (sequences) on the molecules. The integration of these processes allows advancing nanometer-scale electronics. A realistic fabrication scheme for a room-temperature single-electron transistor

  12. Nanosize Effects on Structural and Electrlcal Properties of Conjugated Polymer Nanowires

    Institute of Scientific and Technical Information of China (English)

    J.L.Duvail; Y.Long; J.M.Lorcy; S.Cuenot; O.Chauvet; Z.Chen; C.Gu

    2007-01-01

    1 Introduction Conjugated polymer nanofibers (nanowires,nanotubes,nanorods) are promising as building-blocks for many applications,such as bio- and chemical sensors and drug release,field emission or electrochromic displays,nanodevices,and nano OLEDs.Understanding the mechanisms responsible for their unique electrical,optical and electrochemical properties is thus a foremost point.Here,we report for the first time on a systematic study with the diameter of the electrical properties in Poly(3,4-ethylened...

  13. Horizontal Assembly of Single Nanowire Diode Fabricated by p-n Junction GaN NW Grown by MOCVD

    Directory of Open Access Journals (Sweden)

    Ji-Hyeon Park

    2014-01-01

    Full Text Available Uniaxially p-n junction gallium nitride nanowires have been synthesized via metal-organic chemical vapor deposition method. Nanowires prepared on Si(111 substrates were found to grow perpendicular to the substrate, and the transmission electron microscopy studies demonstrated that the nanowires had singlecrystalline structures with a growth axis. The parallel assembly of the p-n junction nanowire was prepared on a Si substrate with a thermally grown SiO2 layer. The transport studies of horizontal gallium nitride nanowire structures assembled from p- and n-type materials show that these junctions correspond to well-defined p-n junction diodes. The p-n junction devices based on GaN nanowires suspended over the electrodes were fabricated and their electrical properties were investigated. The horizontally assembled gallium nitride nanowire diodes suspended over the electrodes exhibited a substantial increase in conductance under UV light exposure. Apart from the selectivity to different light wavelengths, high responsivity and extremely short response time have also been obtained.

  14. Self-Assembled Conjugated Polymer Nanometer Scale Devices

    Institute of Scientific and Technical Information of China (English)

    Wenping Hu; Hiroshi Nakashima; Keiichi Torimitsu; Yunqi Liu; Daoben Zhu

    2005-01-01

    @@ 1Introduction Nanometer scale devices, as the next generation devices of electronics, have got a worldwide attention and rapid development recently. Simultaneously, conjugated polymers have been applied in organic electronics successfully because of their outstanding electronic-photonic properties. However, as far as we know few reports have dealt with the fabrication of nanometer scale devices by using conjugated polymers, although the combination of nanometer scale devices and polymers will not only extend conjugated polymers to Nanoelectronics, but also excavate the behaviors of polymer molecules at nano-molecular level, such as the electron transport through polymer molecules. One reason for this case is due to the lack of rigidity for most polymers.It results in the failure to bridge them between electrodes or to stand on substrates, therefore, fails to be characterized by scanning probe microscopy. Another reason is that the non-functionalized end-group of most polymers is impossible to graft on substrates through chemical bonds. Here, we introduce a self-assembled conjugated polymer can be used to fabricate nanodevices by self-assembly. The conjugated polymer is a derivative of poly(p-phenyleneethynylene)s (PPE) with thioacetyl end groups (Fig. 1). In general, it is known that for self-assembling ideal nanojunctions the materials should possess: a) conductivity, b) rigidity (for wiring and bridging between electrodes), and c) connectivity (for covalent attachment to metallic or semiconductor solid surfaces). PPE provides good conductivity owing to its special π-conjugated configuration. It is also believed that in principle PPE molecules possess rigidity because of the presence of the triple bond in their molecules,which prevents the rotation of adjacent phenyl rings with respect to each other.

  15. Self-assembled polymer nanocomposites and their networks

    Science.gov (United States)

    Patil, Nitin Vikas

    This dissertation describes new routes to synthesize polymer nanocomposite networks via self-assembly. Polymerizable structure directing agents (referred to as surfmers) obtained by end-group functionalization preserves the structure-directing capabilities of the surfactant for templating ordered mesoporous silica particle growth, while simultaneously generating a reactive matrix for polymer network formation through reactive end groups in the presence of intimately mixed mesoporous silicates. A combination of small angle X-ray scattering, surface area, and microscopy experiments on mesoporous silica indicated the structure directing capabilities of surfmers. Free-radical polymerization of the surfmer leads to novel crosslinked nanocomposites networks. Multiple experiments, including gel permeation chromatography, swelling, and solid state NMR experiments on polymer nanocomposites gave evidence of the polymerization of surfmer leading to formation of crosslink networks. Polymer nanocomposites with varied silica content were prepared. Effects of silica content on polymer nanocomposites were studied on rheometer. Results obtained from rheological experiments indicate that the storage (G') and loss modulus (G") increases with increase in the content of mesoporous silica. In this way, the nanocomposites networks obtained via self-assembly shows independent behavior with respect to frequency in rheological experiments. Additionally, this self-assembled route was extended to synthesize biodegradable and biocompatible polymer nanocomposites networks. The nanocomposite networks obtained with 15% of silica content showed the increase in storage modulus by two orders of magnitude in rheological experiments.

  16. Nanowire polarizers by guided self-assembly of block copolymers

    Science.gov (United States)

    Roberts, Philip M. S.; Baum, Alexandra; Karamath, James; Evans, Allan; Shibata, Satoshi; Walton, Harry

    2014-01-01

    Wire-grid polarizers (WGPs) are currently limited by their wafer-scale manufacturing methods to sizes of approximately 12 to 18 in. For large-size displays, a new method for the production of large-area WGPs is required. Large-area WGPs were simulated using the finite-difference-time-domain method, and a scaleable method for their production based on a block copolymer (BCP)-nanostructured template was implemented. The nanostructured template is globally aligned through the use of a cylinder-forming liquid crystal (LC) diblock copolymer, which is first aligned on a rubbed polyimide substrate. A surface-relief template is produced using the differential dry etch rates of the cylinder-forming component and LC polymer matrix component of the BCP. The template is metalized to produce a WGP. Polarizers of arbitrary size with polarization efficiency up to 0.6 have been made in close agreement with calculated values for idealized structures. The choice of the cylinder-forming polymer is critical to the degree of alignment of the template, and the thermal stability of the LC polymer matrix is critical to the stability of the template during etching.

  17. Design directed self-assembly of donor-acceptor polymers.

    Science.gov (United States)

    Marszalek, Tomasz; Li, Mengmeng; Pisula, Wojciech

    2016-09-21

    Donor-acceptor polymers with an alternating array of donor and acceptor moieties have gained particular attention during recent years as active components of organic electronics. By implementation of suitable subunits within the conjugated backbone, these polymers can be made either electron-deficient or -rich. Additionally, their band gap and light absorption can be precisely tuned for improved light-harvesting in solar cells. On the other hand, the polymer design can also be modified to encode the desired supramolecular self-assembly in the solid-state that is essential for an unhindered transport of charge carriers. This review focuses on three major factors playing a role in the assembly of donor-acceptor polymers on surfaces which are (1) nature, geometry and substitution position of solubilizing alkyl side chains, (2) shape of the conjugated polymer defined by the backbone curvature, and (3) molecular weight which determines the conjugation length of the polymer. These factors adjust the fine balance between attractive and repulsive forces and ensure a close polymer packing important for an efficient charge hopping between neighboring chains. On the microscopic scale, an appropriate domain formation with a low density of structural defects in the solution deposited thin film is crucial for the charge transport. The charge carrier transport through such thin films is characterized by field-effect transistors as basic electronic elements. PMID:27440174

  18. Fabrication of controllable and stable In2O3 nanowire transistors using an octadecylphosphonic acid self-assembled monolayer

    International Nuclear Information System (INIS)

    The controllability and stability of nanowire transistor characteristics are essential for the development of low-noise and fast-switching nano-electronic devices. In this study, the positive shift of threshold voltage and the improvement of interface quality on In2O3 nanowire transistors were simultaneously achieved by using octadecylphosphonic acid (OD-PA) self-assembly. Following the chemical bond of OD-PA molecules on the surface of In2O3 nanowires, the threshold voltage was positively shifted to 2.95 V, and the noise amplitude decreased to approximately 87.5%. The results suggest that an OD-PA self-assembled monolayer can be used to manipulate and stabilize the transistor characteristics of nanowire-based memory and display devices that require high-sensitivity, low-noise, and fast-response. (paper)

  19. Convective polymer assembly for the deposition of nanostructures and polymer thin films on immobilized particles

    Science.gov (United States)

    Richardson, Joseph J.; Björnmalm, Mattias; Gunawan, Sylvia T.; Guo, Junling; LiangPresent Address: Csiro Process Science; Engineering, Clayton, Victoria 3168, Australia, Kang; Tardy, Blaise; SekiguchiPresent Address: Graduate School Of Chemical Sciences; Engineering, Hokkaido University, Sapporo, Japan, Shota; Noi, Ka Fung; Cui, Jiwei; EjimaPresent Address: Institute Of Industrial Science, The University Of Tokyo, Tokyo, Japan, Hirotaka; Caruso, Frank

    2014-10-01

    We report the preparation of polymer particles via convective polymer assembly (CPA). Convection is used to move polymer solutions and cargo through an agarose gel that contains immobilized template particles. This method both coats and washes the particles in a process that is amenable to automation, and does not depend on passive diffusion or electrical currents, thus facilitating incorporation of fragile and nanoscale objects, such as liposomes and gold nanoparticles, into the thin polymer films. Template dissolution leads to the formation of stable polymer particles and capsules.We report the preparation of polymer particles via convective polymer assembly (CPA). Convection is used to move polymer solutions and cargo through an agarose gel that contains immobilized template particles. This method both coats and washes the particles in a process that is amenable to automation, and does not depend on passive diffusion or electrical currents, thus facilitating incorporation of fragile and nanoscale objects, such as liposomes and gold nanoparticles, into the thin polymer films. Template dissolution leads to the formation of stable polymer particles and capsules. Electronic supplementary information (ESI) available: Detailed experimental/instrumental information and supporting figures. See DOI: 10.1039/c4nr04348k

  20. Facile preparation of transparent and conductive polymer films based on silver nanowire/polycarbonate nanocomposites

    Science.gov (United States)

    Moreno, Ivan; Navascues, Nuria; Arruebo, Manuel; Irusta, Silvia; Santamaria, Jesus

    2013-07-01

    Silver nanowires (AgNW) synthesized by a solvothermal method were incorporated into a polycarbonate matrix by a solution mixing procedure. Films with a thickness around 18 μm were obtained, showing a good distribution of the wires within the polymer matrix. The thermal stability of the polymer matrix increased significantly, with the main decomposition peak shifting up to 74 ° C for an AgNW loading of 4.35 wt%. The percolation threshold was obtained at very low AgNW content (0.04 wt%), and the composite electrical conductivity at the maximum loading (4.35 wt%) was 41.3 Ω cm. Excellent transparency was obtained at the percolation threshold, with negligible reduction in the transmittance of the polymer matrix (from 88.2 to 87.6% at 0.04 wt% loading of AgNW). In addition, the polymer matrix protected the silver nanowires from oxidation, as demonstrated by the XPS analysis.

  1. Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

    Institute of Scientific and Technical Information of China (English)

    YANG Cheng; ZHANG Gang; LEE Dae-Young; LI Hua-Min; LIM Young-Dae; Y00 Won Jong; PARK Young-Jun; KIM Jong-Min

    2011-01-01

    Self-assembly of silicon nanowire(SiNW)arrays is studied using SF6/02 plasma treatment. The self-assembly method can be applied to single- and poly-crystalline Si substrates. Plasma conditions can control the length and diameter of the SiNW arrays. Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained. The conducting transparent indium-tin-oxide(ITO) electrode can be fully coated on the self-assembled SiNW arrays by sputtering. The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating. An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.

  2. Efficient Multiscale Models of Polymer Assembly.

    Science.gov (United States)

    Ruiz-Martinez, Alvaro; Bartol, Thomas M; Sejnowski, Terrence J; Tartakovsky, Daniel M

    2016-07-12

    Protein polymerization and bundling play a central role in cell physiology. Predictive modeling of these processes remains an open challenge, especially when the proteins involved become large and their concentrations high. We present an effective kinetics model of filament formation, bundling, and depolymerization after GTP hydrolysis, which involves a relatively small number of species and reactions, and remains robust over a wide range of concentrations and timescales. We apply this general model to study assembly of FtsZ protein, a basic element in the division process of prokaryotic cells such as Escherichia coli, Bacillus subtilis, or Caulobacter crescentus. This analysis demonstrates that our model outperforms its counterparts in terms of both accuracy and computational efficiency. Because our model comprises only 17 ordinary differential equations, its computational cost is orders-of-magnitude smaller than the current alternatives consisting of up to 1000 ordinary differential equations. It also provides, to our knowledge, a new insight into the characteristics and functioning of FtsZ proteins at high concentrations. The simplicity and versatility of our model render it a powerful computational tool, which can be used either as a standalone descriptor of other biopolymers' assembly or as a component in more complete kinetic models. PMID:27410746

  3. Ultralong Ordered Nanowires from the Concerted Self-Assembly of Discotic Liquid Crystal and Solvent Molecules.

    Science.gov (United States)

    Park, Ji Hyun; Kim, Kyung Ho; Park, Yung Woo; Lagerwall, Jan P F; Scalia, Giusy

    2015-09-01

    The realization of long, aligned molecular wires is a great challenge, and a variety of approaches have been proposed. Interestingly, hexapentyloxytriphenylene (HAT5) discotic liquid crystal molecules, a model system of molecules with flat and aromatic cores, can spontaneously form well-aligned, micrometer long, yet only tens of nanometers thick, nanowires on solid surfaces. We have investigated the formation mechanism of these wires using different solvents with selected characteristics, including chemical structure, boiling point, vapor pressure, and surface tension. When casting from toluene and benzene solutions, atomic force microscopy reveals that the discotics spontaneously form very long and thin wires, self-aligning along a common orientation. If instead dodecane or heptane are used, different and in general thicker structures are obtained. The chemical structure of the solvent appears to have a key role, coupling to the liquid crystal self-assembly by allowing solvent molecules to enter the ordered structure if their design matches the core of HAT5 molecules, thereby guiding the assembly. However, other aspects are also relevant in the assembly, including the nature of the substrate and the rate of solvent evaporation, and these can favor or interfere with the self-assembly into long structures. The use of solvents with aromatic structure is advantageous not only because it affects the geometry of the assembly, promoting long wire formation, but it is also compatible with good quality of the intermolecular order, as suggested by a high anisotropy of the Raman spectra of the nanowires formed from these solvents. Finally, the electrical properties of ordered systems show a clearly higher electrical conductivity compared to the disorganized aggregates. PMID:26079283

  4. Aligned and Electrospun Piezoelectric Polymer Fiber Assembly and Scaffold

    Science.gov (United States)

    Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor); Holloway, Nancy M. (Inventor); Leong, Kam W. (Inventor); Kulangara, Karina (Inventor)

    2015-01-01

    A scaffold assembly and related methods of manufacturing and/or using the scaffold for stem cell culture and tissue engineering applications are disclosed which at least partially mimic a native biological environment by providing biochemical, topographical, mechanical and electrical cues by using an electroactive material. The assembly includes at least one layer of substantially aligned, electrospun polymer fiber having an operative connection for individual voltage application. A method of cell tissue engineering and/or stem cell differentiation uses the assembly seeded with a sample of cells suspended in cell culture media, incubates and applies voltage to one or more layers, and thus produces cells and/or a tissue construct. In another aspect, the invention provides a method of manufacturing the assembly including the steps of providing a first pre-electroded substrate surface; electrospinning a first substantially aligned polymer fiber layer onto the first surface; providing a second pre-electroded substrate surface; electrospinning a second substantially aligned polymer fiber layer onto the second surface; and, retaining together the layered surfaces with a clamp and/or an adhesive compound.

  5. Self-Assembly of Emulsion Droplets into Polymer Chains

    Science.gov (United States)

    Bargteil, Dylan; McMullen, Angus; Brujic, Jasna

    We experimentally investigate `beads-on-a-string' models of polymers using the spontaneous assembly of emulsion droplets into linear chains. Droplets functionalized with surface-mobile DNA allow for programmable 'monomers' through which we can influence the three-dimensional structure of the assembled 'polymer'. Such model polymers can be used to study conformational changes of polypeptides and the principles governing protein folding. In our system, we find that droplets bind via complementary DNA strands that are recruited into adhesion patches. Recruitment is driven by the DNA hybridization energy, and is limited by the energy cost of surface deformation and the entropy loss of the mobile linkers, yielding adhesion patches of a characteristic size with a given number of linkers. By tuning the initial surface coverage of linkers, we control valency between the droplets to create linear or branched polymer chains. We additionally control the flexibility of the model polymers by varying the salt concentration and study their dynamics between extended and collapsed states. This system opens the possibility of programming stable three-dimensional structures, such as those found within folded proteins.

  6. Improving the cycling stability of silicon nanowire anodes with conducting polymer coatings

    KAUST Repository

    Yao, Yan

    2012-01-01

    For silicon nanowires (Si NWs) to be used as a successful high capacity lithium-ion battery anode material, improvements in cycling stability are required. Here we show that a conductive polymer surface coating on the Si NWs improves cycling stability; coating with PEDOT causes the capacity retention after 100 charge-discharge cycles to increase from 30% to 80% over bare NWs. The improvement in cycling stability is attributed to the conductive coating maintaining the mechanical integrity of the cycled Si material, along with preserving electrical connections between NWs that would otherwise have become electrically isolated during volume changes. © 2012 The Royal Society of Chemistry.

  7. Use of self-assembled peptide nanostructures for the fabrication of silicon nanowires

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tania;

    2011-01-01

    1. INTRODUCTION Self-assembled diphenylalanine peptide nanotubes provide a means of achieving nanostructured materials in a very simple and fast way. Recent discoveries have shown that this unique material, in addition to remaining stable under dry conditions, rapidly dissolves in water making...... it a promising candidate for controlled nanofabrication without organic solvents [1]. The present work demonstrates how this unique structure can be used as both an etching mask in a dry etching procedure and as a lift-off material. As a further demonstration of the potential of this technique, the peptide...... photolithography, and after deposition of the electrodes, self-assembled peptide nanotubes (PNT), figure 1, were positioned on top of the electrodes. The silicon nanowires were then etched in a reactive ion etching process masked by the positioned peptide nanotubes. Finally, the peptide nanotubes were dissolved...

  8. Templated Self-Assembly of Ultrathin Gold Nanowires by Nanoimprinting for Transparent Flexible Electronics.

    Science.gov (United States)

    Maurer, Johannes H M; González-García, Lola; Reiser, Beate; Kanelidis, Ioannis; Kraus, Tobias

    2016-05-11

    We fabricated flexible, transparent, and conductive metal grids as transparent conductive materials (TCM) with adjustable properties by direct nanoimprinting of self-assembling colloidal metal nanowires. Ultrathin gold nanowires (diameter below 2 nm) with high mechanical flexibility were confined in a stamp and readily adapted to its features. During drying, the wires self-assembled into dense bundles that percolated throughout the stamp. The high aspect ratio and the bundling yielded continuous, hierarchical superstructures that connected the entire mesh even at low gold contents. A soft sintering step removed the ligand barriers but retained the imprinted structure. The material exhibited high conductivities (sheet resistances down to 29 Ω/sq) and transparencies that could be tuned by changing wire concentration and stamp geometry. We obtained TCMs that are suitable for applications such as touch screens. Mechanical bending tests showed a much higher bending resistance than commercial ITO: conductivity dropped by only 5.6% after 450 bending cycles at a bending radius of 5 mm. PMID:26985790

  9. Assembly and Characterization of Coordination Polymer Nanostructural Materials at Interfaces

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Molecular self-assembly of one-/two-dimensional (1D/2D) nanostructures has recently received great interest because the specific structures of crystals determine their unique physical and chemical properties. Coordination polymers contain two central components, connectors and linkers. Transition metal ions are often used as versatile connectors, with coordination numbers ranging from 2 to 7 dependant on the oxidation states of the metal ions. Multidentate ligands are often used as linkers, wh...

  10. Protein Biosensors Based on Polymer Nanowires, Carbon Nanotubes and Zinc Oxide Nanorods

    Directory of Open Access Journals (Sweden)

    Taeksoo Ji

    2011-05-01

    Full Text Available The development of biosensors using electrochemical methods is a promising application in the field of biotechnology. High sensitivity sensors for the bio-detection of proteins have been developed using several kinds of nanomaterials. The performance of the sensors depends on the type of nanostructures with which the biomaterials interact. One dimensional (1-D structures such as nanowires, nanotubes and nanorods are proven to have high potential for bio-applications. In this paper we review these three different kinds of nanostructures that have attracted much attention at recent times with their great performance as biosensors. Materials such as polymers, carbon and zinc oxide have been widely used for the fabrication of nanostructures because of their enhanced performance in terms of sensitivity, biocompatibility, and ease of preparation. Thus we consider polymer nanowires, carbon nanotubes and zinc oxide nanorods for discussion in this paper. We consider three stages in the development of biosensors: (a fabrication of biomaterials into nanostructures, (b alignment of the nanostructures and (c immobilization of proteins. Two different methods by which the biosensors can be developed at each stage for all the three nanostructures are examined. Finally, we conclude by mentioning some of the major challenges faced by many researchers who seek to fabricate biosensors for real time applications.

  11. Electrophoretic deposition of ZnO nanostructures: Au nanoclusters on Si substrates induce self-assembled nanowire growth

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, Claudia [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Marin, Oscar [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Real, Silvina [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Comedi, David [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Tirado, Mónica, E-mail: mtirado@herrera.unt.edu.ar [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina)

    2014-09-15

    Highlights: • ZnO nanowires were grown on silicon substrate by electrophoretic deposition technique without use a porous template. • The growth was induced by Au nanoclusters and was performed at room temperature. • The photoluminescence spectrum for the nanowires obtained shows a broad UV-blue excitonic emission peak and a low emission in the green region. - Abstract: The present work reports the self-assembled growth of ZnO nanowires on silicon substrate with nanometer sized Au clusters using electrophoretic deposition technique at room temperature without a sacrificial template. A colloidal suspension of ≈5 nm sized ZnO nanoparticles dispersed in 2-propanol was used (nanoparticle bandgap of 3.47 eV as determined from absorbance measurements). The results show that the Au nanoclusters on the silicon substrate induce the self-assembly of the ZnO nanoparticles into vertically aligned ZnO nanowires. This effect is tentatively explained as being due to increased electric field intensities near the Au nanoclusters during the electrophoretic deposition. Photoluminescence measurements reveal the presence of quantum confined excitons and a relatively low concentration of deep defects in the nanowires. The electric field guided growth of semiconductor nanostructures at room temperature has great industrial potential as it minimizes production costs and enables the use of substrate materials not withstanding high temperatures.

  12. Layer-by-layer assembly of nanowires for three-dimensional, multifunctional electronics.

    Science.gov (United States)

    Javey, Ali; Nam, SungWoo; Friedman, Robin S; Yan, Hao; Lieber, Charles M

    2007-03-01

    We report a general approach for three-dimensional (3D) multifunctional electronics based on the layer-by-layer assembly of nanowire (NW) building blocks. Using germanium/silicon (Ge/Si) core/shell NWs as a representative example, ten vertically stacked layers of multi-NW field-effect transistors (FETs) were fabricated. Transport measurements demonstrate that the Ge/Si NW FETs have reproducible high-performance device characteristics within a given device layer, that the FET characteristics are not affected by sequential stacking, and importantly, that uniform performance is achieved in sequential layers 1 through 10 of the 3D structure. Five-layer single-NW FET structures were also prepared by printing Ge/Si NWs from lower density growth substrates, and transport measurements showed similar high-performance characteristics for the FETs in layers 1 and 5. In addition, 3D multifunctional circuitry was demonstrated on plastic substrates with sequential layers of inverter logical gates and floating gate memory elements. Notably, electrical characterization studies show stable writing and erasing of the NW floating gate memory elements and demonstrate signal inversion with larger than unity gain for frequencies up to at least 50 MHz. The ability to assemble reproducibly sequential layers of distinct types of NW-based devices coupled with the breadth of NW building blocks should enable the assembly of increasing complex multilayer and multifunctional 3D electronics in the future.

  13. Polymer-template-assisted growth of gold nanowires using a novel flow-stream technique.

    Science.gov (United States)

    Metwalli, E; Moulin, J-F; Perlich, J; Wang, W; Diethert, A; Roth, S V; Müller-Buschbaum, P

    2009-10-01

    By utilizing a fluidic device, a gold nanoparticle dispersion is cast onto a nanostructured polymer template using solution subjected to hydrodynamic flow. With in situ grazing incidence small-angle X-ray scattering (GISAXS), the progressive gold deposition from a stream of gold solution onto the polymer template of a diblock copolymer with parallel cylinder morphology arranged into powder-like domains is investigated. The continuously flowing solution causes a systematic increase in the X-ray contrast between both of the microphase-separated blocks of the block copolymer film, indicating flow-induced selective gold immobilization on one block. Both in situ GISAXS data and atomic force microscopy of the metal-deposited polymer film prove the 1D coalescence of nanoparticles into continuous nanowires. With additional gold nanoparticle upload by the continuous flow-stream method, the selectivity of the nanoparticle deposition diminishes as a result of the formation of a pseudo uniform gold layer. Consequently, this flow-stream deposition technique introduces an easy alternative method to the vapor deposition technique for surface gold nanopatterning. PMID:19572494

  14. High stability of self-assembled peptide nanowires against thermal, chemical, and proteolytic attacks.

    Science.gov (United States)

    Ryu, Jungki; Park, Chan Beum

    2010-02-01

    Understanding the self-assembly of peptides into ordered nanostructures is recently getting much attention since it can provide an alternative route for fabricating novel bio-inspired materials. In order to realize the potential of the peptide-based nanofabrication technology, however, more information is needed regarding the integrity or stability of peptide nanostructures under the process conditions encountered in their applications. In this study, we investigated the stability of self-assembled peptide nanowires (PNWs) and nanotubes (PNTs) against thermal, chemical, proteolytic attacks, and their conformational changes upon heat treatment. PNWs and PNTs were grown by the self-assembly of diphenylalanine (Phe-Phe), a peptide building block, on solid substrates at different chemical atmospheres and temperatures. The incubation of diphenylalanine under aniline vapor at 150 degrees C led to the formation of PNWs, while its incubation with water vapor at 25 degrees C produced PNTs. We analyzed the stability of peptide nanostructures using multiple tools, such as electron microscopy, thermal analysis tools, circular dichroism, and Fourier-transform infrared spectroscopy. Our results show that PNWs are highly stable up to 200 degrees C and remain unchanged when incubated in aqueous solutions (from pH 1 to 14) or in various chemical solvents (from polar to non-polar). In contrast, PNTs started to disintegrate even at 100 degrees C and underwent a conformational change at an elevated temperature. When we further studied their resistance to a proteolytic environment, we discovered that PNWs kept their initial structure while PNTs fully disintegrated. We found that the high stability of PNWs originates from their predominant beta-sheet conformation and the conformational change of diphenylalanine nanostructures. Our study suggests that self-assembled PNWs are suitable for future nano-scale applications requiring harsh processing conditions. PMID:19777585

  15. Phosphorylcholine substituted polyolefins: New syntheses, solution assemblies, and polymer vesicles

    Science.gov (United States)

    Kratz, Katrina A.

    This thesis describes the synthesis and applications of a new series of amphiphilic homopolymers and copolymers consisting of hydrophobic polyolefin backbone and hydrophilic phosphorylcholine (PC) pendant groups. These polymers are synthesized by ring opening metathesis polymerization (ROMP) of a novel PC- cyclooctene monomer, and copolymerization of various functionalized cyclooctene comonomers. Incorporation of different comonomers into the PC-polyolefin backbone affords copolymers with different functionalities, including crosslinkers, fluorophores, and other reactive groups, that tune the range of applications of these polymers, and their hydrophobic/hydrophilic balance. The amphiphilic nature of PC-polyolefins was exploited in oil-water interfacial assembly, providing robust polymer capsules to encapsulate and deliver nanoparticles to damaged regions of a substrate in a project termed `repair-and-go.' In repair-and-go, a flexible microcapsule filled with a solution of nanoparticles probes an imperfection-riddled substrate as it rolls over the surface. The thin capsule wall allows the nanoparticles to escape the capsules and enter into the cracks, driven in part by favorable interactions between the nanoparticle ligands and the cracked surface (i.e., hydrophobic-hydrophobic interactions). The capsules then continue their transport along the surface, filling more cracks and depositing particles into them. The amphiphilic nature of PC-polyolefins was also exploited in aqueous assembly, forming novel polymer vesicles in water. PC-polyolefin vesicles ranged in size from 50 nm to 30 µm. The mechanical properties of PC-polyolefin vesicles were measured by micropipette aspiration techniques, and found to be more robust than conventional liposomes or polymersomes prepared from block copolymers. PC-polyolefin vesicles have potential use in drug delivery; it was found that the cancer drug doxorubicin could be encapsulated efficiently in PC-polyolefin vesicles. In

  16. Influence of the polymer matrix on the efficiency of hybrid solar cells based on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ben Dkhil, S., E-mail: sadok.bendekhil@gmail.com [Laboratoire Physique des Materiaux: Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Ingenierie des Materiaux Polymeres: IMP, UMR CNRS 5223, Universite Claude Bernard Lyon 1, 15 boulevard Latarjet, 69622 Villeurbanne (France); Bourguiga, R. [Laboratoire Physique des Materiaux: Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Davenas, J. [Ingenierie des Materiaux Polymeres: IMP, UMR CNRS 5223, Universite Claude Bernard Lyon 1, 15 boulevard Latarjet, 69622 Villeurbanne (France); Cornu, D. [Institut Europeen des Membranes, UMR CNRS 5635, Ecole Nationale superieure de Chimie, Universite de Montpellier, 1919 route de Mende, 34000 Montpellier (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Hybrid solar cells based on silicon nanowires have been fabricated. Black-Right-Pointing-Pointer The relation between the morphology of the composite thin films and the charge transfer between the polymer matrices and SiNWs has been examined. Black-Right-Pointing-Pointer We have investigated the effect of the polymer matrix on the photovoltaic characteristics. - Abstract: Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV-vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor-acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current-voltage (I-V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies.

  17. Component assembly with shape memory polymer fastener for microrobots

    International Nuclear Information System (INIS)

    Adhesives are generally used for the assembly of microrobots, whereas bolts, screws, or rivets are used for larger robots. Although adhesives are easy to apply, lightweight, and small, they cannot be used for repeated assembly and disassembly of parts. In this paper, we present a novel microfastener composed of a polyurethane-based shape memory polymer (SMP) that is lightweight and small but that is easily detached for disassembly. This was achieved by using the shape recovery and modulus change of the SMP. A sheet of macromolded SMP was laser machined into an I-beam-shaped rivet, and notches were added to the structure to prevent stress concentration. Pull-off tests showed that, as the notch radius increased, the disengagement strength of the rivet fastener decreased and the reusability increased. Through the elastoplastic model, a single SMP rivet was calculated to have maximum disengagement strength of 150 N cm−2 in the elastic range, depending on the notch radius. The fasteners were applied to a jumping microrobot. The legs and body were assembled with ten fasteners, which showed no permanent deformation after impact during jumping movements. The legs were easily replaced with ones of different stiffness by heating the engaged sites to make the fasteners compliant and detachable. The proposed detachable SMP microfasteners are particularly useful for testing the isolated performance of microrobot components to determine the optimal designs for these components. (paper)

  18. Hybrid Thin Films Based Upon Polyoxometalates-Polymer Assembly

    Science.gov (United States)

    Qi, Na; Jing, Benxin; Zhu, Yingxi

    2014-03-01

    Block copolymers (BCPs) and polyoxometalates (POMs) have been used individually as building blocks for design and synthesis of novel functional materials. POM nanoclusters, the assemblies of transition metal oxides with well-defined atomic coordination structure, have been recently explored as novel nanomaterials... for catalysis, semiconductors, and even anti-cancer treatment due to their unique chemical, optical and electrical characteristics. We have explored the blending of inorganic POM nanocluster with BCPs into hierarchaically structured inorganic-organic hybrid nanocomposites. Using polystyrene-b-poly(ethylene oxide) (PS-b-PEO) thin films as the template, we have observed that the spatial organization of BCP thin films is modified by molybdenum based POM nanocluster to form 2D in-plane hexagonal ordered or 3D ordered network of POM-BCP assemblies, depending on the concentration ratio of POM to PS-b-PEO. The dielectric properties of such hybrid thin films can be enhanced by embedded POMs but show a strong dependence on the supramolecular structures of POM-polymer complexes. The assembly of nanoclusters in BCP-templated thin films could pave a new path to design new hybrid nanocomposites with uniquely combined functionality and material properties.

  19. Patterning of self-assembled monolayers by phase-shifting mask and its applications in large-scale assembly of nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Fan; Zhang, Dakuan; Wang, Jianyu; Sheng, Yun; Wang, Xinran; Chen, Kunji; Zhou, Minmin [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yan, Shancheng [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Shen, Jiancang; Pan, Lijia; Shi, Yi, E-mail: yshi@nju.edu.cn [Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Micro-structures, Nanjing University, Nanjing 210093 (China)

    2015-01-26

    A nonselective micropatterning method of self-assembled monolayers (SAMs) based on laser and phase-shifting mask (PSM) is demonstrated. Laser beam is spatially modulated by a PSM, and periodic SAM patterns are generated sequentially through thermal desorption. Patterned wettability is achieved with alternating hydrophilic/hydrophobic stripes on octadecyltrichlorosilane monolayers. The substrate is then used to assemble CdS semiconductor nanowires (NWs) from a solution, obtaining well-aligned NWs in one step. Our results show valuably the application potential of this technique in engineering SAMs for integration of functional devices.

  20. Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof

    Science.gov (United States)

    Licsandru, Erol-Dan; Schneider, Susanne; Tingry, Sophie; Ellis, Thomas; Moulin, Emilie; Maaloum, Mounir; Lehn, Jean-Marie; Barboiu, Mihail; Giuseppone, Nicolas

    2016-03-01

    Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting

  1. Crystallization-driven assembly of conjugated-polymer-based nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hayward, Ryan C. [Univ. of Massachusetts, Amherst, MA (United States). Polymer Science & Engineering

    2016-10-15

    The goal of this project has been to improve our ability to simultaneously control the organization, and therefore the opto-electronic properties, of conjugated-polymer based materials across three different length-scales: 1) the molecular scale, in the sense of controlling growth and functionalization of highly crystalline semiconducting organic materials capable of efficient charge transport, 2) the nanoscale, in terms of positioning n- and p-type materials with domain sizes comparable to exciton diffusion lengths (~ 10 nm) to facilitate charge separation, and 3) the colloidal scale, such that well-defined crystalline nanoscale building blocks can be hierarchically organized into device layers. As described in more detail below, the project was successful in generating powerful new approaches to, and improved fundamental understanding of, processing and self-assembly of organic and hybrid semiconducting materials across all three length-scales. Although the goals of the project were formulated with primarily photovoltaic architectures in mind, the outcomes of the project have significant implications for a variety of conjugated-polymer-based devices including field-effect-transistors for sensors and logic devices, as well as potentially thermoelectrics and battery electrode materials. The project has resulted in 10 peer-reviewed publications to date [1-10], with several additional manuscripts currently in preparation.

  2. Controlled growth mechanism of poly (3-hexylthiophene) nanowires

    Science.gov (United States)

    Kiymaz, D.; Yagmurcukardes, M.; Tomak, A.; Sahin, H.; Senger, R. T.; Peeters, F. M.; Zareie, H. M.; Zafer, C.

    2016-11-01

    Synthesis of 1D-polymer nanowires by a self-assembly method using marginal solvents is an attractive technique. While the formation mechanism is poorly understood, this method is essential in order to control the growth of nanowires. Here we visualized the time-dependent assembly of poly (3-hexyl-thiophene-2,5-diyl) (P3HT) nanowires by atomic force microscopy and scanning tunneling microscopy. The assembly of P3HT nanowires was carried out at room temperature by mixing cyclohexanone (CHN), as a poor solvent, with polymer solution in 1,2-dichlorobenzene (DCB). Both π–π stacking and planarization, obtained at the mix volume ratio of P3HT (in DCB):CHN (10:7), were considered during the investigation. We find that the length of nanowires was determined by the ordering of polymers in the polymer repetition direction. Additionally, our density functional theory calculations revealed that the presence of DCB and CHN molecules that stabilize the structural distortions due to tail group of polymers was essential for the core-wire formation.

  3. Enhancing Crystalline Structural Orders of Polymer Semiconductors for Efficient Charge Transport via Polymer-Matrix-Mediated Molecular Self-Assembly.

    Science.gov (United States)

    Lei, Yanlian; Deng, Ping; Lin, Ming; Zheng, Xuelin; Zhu, Furong; Ong, Beng S

    2016-08-01

    A facile polymer-matrix-mediated molecular self-assembly of polymer semiconductors into highly crystalline orders for efficient charge transport in organic thin-film transistors is demonstrated. Phenomenal enhancements in field-effect mobility of about one order of magnitude and current on/off ratio of two to three orders of magnitude are realized with polyacrylonitrile-incorporated polymer semiconductor compositions via solution deposition. PMID:27168128

  4. Measuring photoluminescence spectra of self-assembly array nanowire of colloidal CdSe quantum dots using scanning near-field optics microscopy

    Science.gov (United States)

    Bai, Zhongchen; Hao, Licai; Zhang, Zhengping; Qin, Shuijie

    2016-05-01

    A novel periodic array CdSe nanowire is prepared on a substrate of the porous titanium dioxide by using a self-assembly method of the colloidal CdSe quantum dots (QDs). The experimental results show that the colloidal CdSe QDs have renewedly assembled on its space scale and direction in process of losing background solvent and form the periodic array nanowire. The main peak wavelength of Photoluminescence (PL) spectra, which is measured by using a 100-nm aperture laser beam spot on a scanning near-field optics microscopy, has shifted 60 nm with compared to the colloidal CdSe QDs. Furthermore, we have measured smaller ordered nanometer structure in thin QDs area as well, a 343-nm periodic nanowire in thick QDs area and the colloidal QDs in edge of well-ordered nanowire.

  5. Temperature-induced reversible self-assembly of diphenylalanine peptide and the structural transition from organogel to crystalline nanowires.

    Science.gov (United States)

    Huang, Renliang; Wang, Yuefei; Qi, Wei; Su, Rongxin; He, Zhimin

    2014-01-01

    Controlling the self-assembly of diphenylalanine peptide (FF) into various nanoarchitectures has received great amounts of attention in recent years. Here, we report the temperature-induced reversible self-assembly of diphenylalanine peptide to microtubes, nanowires, or organogel in different solvents. We also find that the organogel in isopropanol transforms into crystalline flakes or nanowires when the temperature increases. The reversible self-assembly in polar solvents may be mainly controlled by electronic and aromatic interactions between the FF molecules themselves, which is associated with the dissociation equilibrium and significantly influenced by temperature. We found that the organogel in the isopropanol solvent made a unique transition to crystalline structures, a process that is driven by temperature and may be kinetically controlled. During the heating-cooling process, FF preferentially self-assembles to metastable nanofibers and organogel. They further transform to thermodynamically stable crystal structures via molecular rearrangement after introducing an external energy, such as the increasing temperature used in this study. The strategy demonstrated in this study provides an efficient way to controllably fabricate smart, temperature-responsive peptide nanomaterials and enriches the understanding of the growth mechanism of diphenylalanine peptide nanostructures. PMID:25520600

  6. Formation of polymer nanowires through electropolymerization of polybithiophene from mixed electrolyte solutions of tetrabutylammonium hexafluorophosphate and tetrabutylammonium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Kantzas, Trissa T. [Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7 (Canada); Semenikhin, Oleg A., E-mail: osemenik@uwo.c [Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7 (Canada)

    2011-04-01

    Preparation of one-dimensional conducting polymer structures such as nanowires and nanotubes require anisotropic growth conditions. Usually, such conditions are achieved by applying a certain template or by patterning the substrate. In this work, we employ a new approach to facilitate the anisotropic growth of electrochemically deposited polybithiophene through variations of the conductivity of the growing material. If the deposited material varies in conductivity, the areas with less conducting material will sustain little or no electrochemical current and only the areas with sufficient conductivity will experience further growth. In this work, the conductivity variations and the resulting anisotropic growth are achieved by performing electropolymerization in mixed electrolyte solutions of tetrabutylammonium hexafluorophosphate and tetrabutylammonium chloride. No growth can be observed in pure tetrabutylammonium chloride because the resulting films are insulating. However, addition of small amounts of tetrabutylammonium hexafluorophosphate was found to selectively activate local nanometer-sized areas of the polymer surface where polymer nanowire growth was observed. The latter was confirmed by atomic-force microscopy (AFM). The local properties of the polymer nanostructures obtained with varying contents of tetrabutylammonium hexafluorophosphate were characterized.

  7. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode

    Science.gov (United States)

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-01

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PEDOT:PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  8. Self-assembly of conjugated oligomers and polymers at the interface: structure and properties.

    Science.gov (United States)

    Xu, Lirong; Yang, Liu; Lei, Shengbin

    2012-08-01

    In this review, we give a brief account on the recent scanning tunneling microscopy investigation of interfacial structures and properties of π-conjugated semiconducting oligomers and polymers, either at the solid-air (including solid-vacuum) or at the solid-liquid interface. The structural aspects of the self-assembly of both oligomers and polymers are highlighted. Conjugated oligomers can form well ordered supramolecular assemblies either at the air-solid or liquid-solid interface, thanks to the relatively high mobility and structural uniformity in comparison with polymers. The backbone structure, substitution of side chains and functional groups can affect the assembling behavior significantly, which offers the opportunity to tune the supramolecular structure of these conjugated oligomers at the interface. For conjugated polymers, the large molecular weight limits the mobility on the surface and the distribution in size also prevents the formation of long range ordered supramolecular assembly. The submolecular resolution obtained on the assembling monolayers enables a detailed investigation of the chain folding at the interface, both the structural details and the effect on electronic properties. Besides the ability in studying the assembling structures at the interfaces, STM also provides a reasonable way to evaluate the distribution of the molecular weight of conjugated polymers by statistic of the contour length of the adsorbed polymer chains. Both conjugated oligomers and polymers can form composite assemblies with other materials. The ordered assembly of oligomers can act as a template to controllably disperse other molecules such as coronene or fullerene. These investigations open a new avenue to fine tune the assembling structure at the interface and in turn the properties of the composite materials. To summarize scanning tunneling microscopy has demonstrated its surprising ability in the investigation of the assembling structures and properties of

  9. Self-Assembled Polymer Light-Emitting Devices

    Science.gov (United States)

    Rubner, Michael

    1996-03-01

    A new layer-by-layer process involving the alternate spontaneous adsorption of oppositely charged polymers onto substrate surfaces has been utilized to fabricate a number of novel thin film multilayer heterostructures with electrical and optical properties that can be tuned at the molecular level. Using this process, we have fabricated large area, thin film light emitting devices based on multilayer heterostructures of poly(p-phenylene vinylene) (PPV) and various polyanions. The nature of the polyanion used to assemble the PPV multilayers was found to dramatically influence the emission wavelength, intensity and charge transport capabilities of the thin films. Active layer thicknesses ranging from as thin as 8 nm to about 150 nm were readily prepared using this new technique. Light emitting devices with high luminance levels (>500 cd/m2 in the range of 5-12 volts) and tunable emission wavelengths have been created through the use of multi-bilayer "slab" systems that are used to control the charge injection and transport characteristics of the device. Since this is a molecular layer-by-layer fabrication technique, it is also possible to readily manipulate the nature of the polymer/electrode interfaces present in these devices. We have found, for example, that the addition of a 3 nm thick insulating layer at the PPV/aluminum interface improves device efficiency by as much as a factor of five. Details concerning the behavior of these new devices and the mechanisms of charge injection and transport operating in these new multilayer thin films will be discussed.

  10. Hybrid solar cells with conducting polymers and vertically aligned silicon nanowire arrays: The effect of silicon conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sungho, E-mail: shwoo@dgist.ac.kr [Green Energy Research Division, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of); Hoon Jeong, Jae [Green Energy Research Division, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of); Organic Nanoelectronics Laboratory, Department of Chemical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kun Lyu, Hong; Jeong, Seonju; Hyoung Sim, Jun; Hyun Kim, Wook [Green Energy Research Division, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of); Soo Han, Yoon [Department of Advanced Energy Material Science and Engineering, Catholic University of Daegu, Gyeongbuk 712-702 (Korea, Republic of); Kim, Youngkyoo, E-mail: ykimm@knu.ac.kr [Organic Nanoelectronics Laboratory, Department of Chemical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2012-08-01

    Organic/inorganic hybrid solar cells, based on vertically aligned n-type silicon nanowires (n-Si NWs) and p-type conducting polymers (PEDOT:PSS), were investigated as a function of Si conductivity. The n-Si NWs were easily prepared from the n-Si wafer by employing a silver nanodot-mediated micro-electrochemical redox reaction. This investigation shows that the photocurrent-to-voltage characteristics of the n-Si NW/PEDOT:PSS cells clearly exhibit a stable rectifying diode behavior. The increase in current density and fill factor using high conductive silicon is attributed to an improved charge transport towards the electrodes achieved by lowering the device's series resistance. Our results also show that the surface area of the nanowire that can form heterojunction domains significantly influences the device performance.

  11. Self-assembly of cadmium metasilicate nanowires as a broadband optical limiter

    Science.gov (United States)

    Zheng, Chan; Dai, Chongchong; Huang, Li; Li, Wei; Chen, Wenzhe

    2016-04-01

    Cadmium metasilicate nanowires (CdSiO3 NWs) have been synthesized through a facile, eco-friendly, low-cost water-ethanol mixed-solution hydrothermal route. The transmission electron microscopy measurements of as-prepared samples indicate that the CdSiO3 NWs with diameters in the range of 10-60 nm and lengths of more than 1 μm were constructed by self-assembly of 5-10-nm CdSiO3 nanoparticles with good crystallinity. The monoclinic phase formation of the sample is studied in detail by X-ray diffraction, Fourier-transform infrared spectroscopy, and thermo gravimetric analysis. The results indicate that a pure monoclinic phase of CdSiO3 can be obtained by a hydrothermal route without further calcinations and SiO4 tetrahedra were the main constituents of the CdSiO3 NWs. The nanosecond optical limiting (OL) effects were characterized by using an open-aperture (OA) Z-scan technique with 4-ns laser pulses at both 532 and 1064 nm. Theses CdSiO3 NWs displayed an excellent OL performance at 532 and 1064 nm, which was better than carbon nanotubes, a benchmark optical limiter. Input-fluence dependent scattering measurements suggested than nonlinear scattering played an important role in the observed optical limiting behavior in CdSiO3 NWs at 532 and 1064 nm. More significantly, the NLO performance in CdSiO3 NWs incorporated solid silica gel glass has been improved in comparison to those dispersed in water. The unique structure and excellent OL property render these CdSiO3 NWs competitors in the realms of optical limiting applications.

  12. Membrane electrode assemblies for unitised regenerative polymer electrolyte fuel cells

    Science.gov (United States)

    Wittstadt, U.; Wagner, E.; Jungmann, T.

    Membrane electrode assemblies for regenerative polymer electrolyte fuel cells were made by hot pressing and sputtering. The different MEAs are examined in fuel cell and water electrolysis mode at different pressure and temperature conditions. Polarisation curves and ac impedance spectra are used to investigate the influence of the changes in coating technique. The hydrogen gas permeation through the membrane is determined by analysing the produced oxygen in electrolysis mode. The analysis shows, that better performances in both process directions can be achieved with an additional layer of sputtered platinum on the oxygen electrode. Thus, the electrochemical round-trip efficiency can be improved by more than 4%. Treating the oxygen electrode with PTFE solution shows better performance in fuel cell and less performance in electrolysis mode. The increase of the round-trip efficiency is negligible. A layer sputtered directly on the membrane shows good impermeability, and hence results in high voltages at low current densities. The mass transportation is apparently constricted. The gas diffusion layer on the oxygen electrode, in this case a titanium foam, leads to flooding of the cell in fuel cell mode. Stable operation is achieved after pretreatment of the GDL with a PTFE solution.

  13. Nanohelices from planar polymer self-assembled in carbon nanotubes

    Science.gov (United States)

    Fu, Hongjin; Xu, Shuqiong; Li, Yunfang

    2016-07-01

    The polymer possessing with planar structure can be activated and guided to encapsulate the inner space of SWNT and form a helix through van der Waals interaction and the π-π stacking effect between the polymer and the inner surface of SWNT. The SWNT size, the nanostructure and flexibility of polymer chain are all determine the final structures. The basic interaction between the polymer and the nanotubes is investigated, and the condition and mechanism of the helix-forming are explained particularly. Hybrid polymers improve the ability of the helix formation. This study provides scientific basis for fabricating helical polymers encapsulated in SWNTs and eventually on their applications in various areas.

  14. Polymeric microtubules that breathe: CO2 -driven polymer controlled-self-assembly and shape transformation.

    Science.gov (United States)

    Yan, Qiang; Zhao, Yue

    2013-09-16

    Tubular breathing motion: Polymer tubules self-assembled from a gas-sensitive triblock copolymer can undergo shape evolution. A sequence from microtubes through submicroscopic vesicles to nanosized spherical micelles is modulated by CO2 stimulation levels.

  15. Bandgap engineering in a nanowire: self-assembled 0, 1 and 2D quantum structures

    Directory of Open Access Journals (Sweden)

    Jordi Arbiol

    2013-06-01

    Full Text Available Inherent to the nanowire morphology is the exciting possibility of fabricating materials organized at the nanoscale in three dimensions. Composition and structure can be varied along and across the nanowire, as well as within coaxial shells. This opens up a manifold of possibilities in nanoscale materials science and engineering which is only possible with a nanowire as a starting structure. As the variation in composition and structure is accompanied by a change in the band structure, it is possible to confine carriers within the nanowire. Interestingly, this results in the formation of local two, one and zero-dimensional structures from an electronic point of view within the nanowire. This novel palette of nano-structures paves the way toward novel applications in many engineering domains such as lasers, high-mobility transistors, quantum information and energy harvesting. In the present review we summarize and give an overview on recent achievements in the design and growth of advanced quantum structures starting from nanowire templates. The quantum structures presented have been grown by molecular beam epitaxy and correspond to different confinement approaches: quantum wells (2D, quantum wires (1D and quantum dots (0D.

  16. Self-assembly of supramolecularly engineered polymers and their biomedical applications.

    Science.gov (United States)

    Wang, Dali; Tong, Gangsheng; Dong, Ruijiao; Zhou, Yongfeng; Shen, Jian; Zhu, Xinyuan

    2014-10-18

    Noncovalent interactions provide a flexible method of engineering various chemical entities with tailored properties. Specific noncovalent interactions between functionalized small molecules, macromolecules or both of them bearing complementary binding sites can be used to engineer supramolecular complexes that display unique structure and properties of polymers, which can be defined as supramolecularly engineered polymers. Due to their dynamic tunable structures and interesting physical/chemical properties, supramolecularly engineered polymers have recently received more and more attention from both academia and industry. In this feature article, we summarize the recent progress in the self-assembly of supramolecularly engineered polymers as well as their biomedical applications. In view of different molecular building units, the supramolecularly engineered polymers can be classified into the following three major types: supramolecularly engineered polymers built by small molecules, supramolecularly engineered polymers built by small molecules and macromolecules, and supramolecularly engineered polymers built by macromolecules, which possess distinct morphologies, definite architectures and specific functions. Owing to the reversible nature of the noncovalent interactions, the supramolecularly engineered polymers have exhibited unique features or advantages in molecular self-assembly, for example, facile preparation and functionalization, controllable morphologies and structures, dynamic self-assembly processes, adjustable performance, and so on. Furthermore, the self-assembled supramolecular structures hold great potential as promising candidates in various biomedical fields, including bioimaging, drug delivery, gene transfection, protein delivery, regenerative medicine and tissue engineering. Such developments in the self-assembly of supramolecularly engineered polymers and their biomedical applications greatly promote the interdiscipline research among

  17. Enhancement of short-circuit current density in polymer bulk heterojunction solar cells comprising plasmonic silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuzhao; Lin, Xiaofeng; Ou, Jiemei; Chen, Xudong, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Sun Yat-sen University, Guangzhou 510275 (China); Qing, Jian; Zhong, Zhenfeng; Zhou, Xiang, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn; Chen, Yujie, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Hu, Chenglong [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan 430056 (China)

    2014-03-24

    We demonstrate that the influence of plasmonic effects based on silver nanowires (Ag NWs) on the characteristics of polymer solar cells (PSCs). The solution-processed Ag NWs are situated at the interface of anode buffer layer and active layer, which could enhance the performance especially the photocurrent of PSCs by scattering, localized surface plasmon resonance, and surface plasmon polaritons. Plasmonic effects are confirmed by the enhancement of extinction spectra, external quantum efficiency, and steady state photoluminescence. Consequently, the short-circuit current density (J{sub sc}) and power conversion efficiency enhance about 24% and 18%, respectively, under AM1.5 illumination when Ag NWs plasmonic nanostructure incorporated into PSCs.

  18. Directed assembly of conducting polymers on sub-micron templates by electrical fields

    International Nuclear Information System (INIS)

    Highlights: ► Nanoscale patterns with dimensions of assembled PANi down to 100 nm were fabricated. ► We use electrophoretic and dielectrophoretic assembly to deposit PANi. ► Electrophoretic and dielectrophoretic assembly of PANi finished in less than 1 min. ► Effect of process parameters on assembly of PANi onto nanoscale pattern was studied. ► The assembled PANi can be transferred to other flexible substrates. - Abstract: Patterning of conducting polymer into sub-micron patterns over large areas at high rate and low cost is significant for commercial manufacturing of novel devices. Electrophoretic and dielectrophoretic assembly provide an easily scaled approach with high fabrication rates. In this work, electrophoretic and dielectrophoretic assembly were used to assemble polyaniline (PANi) into multiscale sub-micron size patterns in less than 1 min. The process was controlled by assembly time, amplitude, and frequency of the electric field. Dielectrophoretic assembly is preferable for manufacturing as it reduces damage to the templates used to control the assembly. Using this method, sub-micron patterns with dimensions of the assembled PANi down to 100 nm were fabricated over large areas in short times. The assembled PANi was further transferred to other flexible polymer substrates by a thermoforming process, providing a fast, easily controlled and promising approach for fabrication of nanoscale devices.

  19. Chemical Sensing with Nanowires

    Science.gov (United States)

    Penner, Reginald M.

    2012-07-01

    Transformational advances in the performance of nanowire-based chemical sensors and biosensors have been achieved over the past two to three years. These advances have arisen from a better understanding of the mechanisms of transduction operating in these devices, innovations in nanowire fabrication, and improved methods for incorporating receptors into or onto nanowires. Nanowire-based biosensors have detected DNA in undiluted physiological saline. For silicon nanowire nucleic acid sensors, higher sensitivities have been obtained by eliminating the passivating oxide layer on the nanowire surface and by substituting uncharged protein nucleic acids for DNA as the capture strands. Biosensors for peptide and protein cancer markers, based on both semiconductor nanowires and nanowires of conductive polymers, have detected these targets at physiologically relevant concentrations in both blood plasma and whole blood. Nanowire chemical sensors have also detected several gases at the parts-per-million level. This review discusses these and other recent advances, concentrating on work published in the past three years.

  20. The cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters as potential gas sensors for CO, NO, and NO2 detection.

    Science.gov (United States)

    Yong, Yongliang; Jiang, Huai; Li, Xiaohong; Lv, Shijie; Cao, Jingxiao

    2016-08-01

    The advances in cluster-assembled materials where clusters serve as building blocks have opened new opportunities to develop ever more sensitive gas sensors. Here, using density functional theory calculations, the structural and electronic properties of cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters and their application as gas sensors have been investigated. Our results show that the nanowires can be produced via the coalescence of stable M12N12 fullerene-like clusters. The M12N12-based nanowires have semiconducting electrical properties with direct energy gaps, and are particularly stable at room temperature for long enough to allow for their characterization and applications. Furthermore, we found that the CO, NO, and NO2 molecules are chemisorbed on the M12N12-based nanowires with reasonable adsorption energies and apparent charge transfer. The electronic properties of the M12N12-based nanowires present dramatic changes after the adsorption of the CO, NO, and NO2 molecules, especially their electric conductivity. However, the adsorption of NO2 on the Al12N12-based nanowire is too strong, indicating an impractical recovery time as NO2 sensors. In addition to this, due to reasonable adsorption energies, apparent charge transfer, change in the electric conductivity, and the short recovery time, the Al12N12-based nanowire should be a good CO and NO sensor with quick response as well as short recovery time, while the Ga12N12-based nanowire should be a promising gas sensor for CO, NO, and NO2 detection. PMID:27424739

  1. Synergy of Two Assembly Languages in DNA Nanostructures: Self-Assembly of Sequence-Defined Polymers on DNA Cages.

    Science.gov (United States)

    Chidchob, Pongphak; Edwardson, Thomas G W; Serpell, Christopher J; Sleiman, Hanadi F

    2016-04-01

    DNA base-pairing is the central interaction in DNA assembly. However, this simple four-letter (A-T and G-C) language makes it difficult to create complex structures without using a large number of DNA strands of different sequences. Inspired by protein folding, we introduce hydrophobic interactions to expand the assembly language of DNA nanotechnology. To achieve this, DNA cages of different geometries are combined with sequence-defined polymers containing long alkyl and oligoethylene glycol repeat units. Anisotropic decoration of hydrophobic polymers on one face of the cage leads to hydrophobically driven formation of quantized aggregates of DNA cages, where polymer length determines the cage aggregation number. Hydrophobic chains decorated on both faces of the cage can undergo an intrascaffold "handshake" to generate DNA-micelle cages, which have increased structural stability and assembly cooperativity, and can encapsulate small molecules. The polymer sequence order can control the interaction between hydrophobic blocks, leading to unprecedented "doughnut-shaped" DNA cage-ring structures. We thus demonstrate that new structural and functional modes in DNA nanostructures can emerge from the synergy of two interactions, providing an attractive approach to develop protein-inspired assembly modules in DNA nanotechnology. PMID:26998893

  2. Preparation and thermal stability of nickel nanowires via self-assembly process under magnetic field

    Indian Academy of Sciences (India)

    Hu Wang; Ming Li; Xiaoyu Li; Kenan Xie; Li Liao

    2015-09-01

    Nickel nanowires were synthesized via a template-free method in an aqueous solution system combined with chemical reduction and magnetic field. The suitable concentration of Ni ions and reaction time were controlled in order to obtain nickel wires with uniform sizes. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetry and differential scanning calorimetry. The results showed that the Ni nanowires with large aspect ratio up to 200 had uniform size and morphology, about 200 nm. Especially, it is noteworthy that the samples were stable in air when the temperature was lower than 318°C. The study would provide a facile method to prepare nickel nanowires with homogeneous diameter and high thermal stability, which could be used in catalysing CO2 hydrogenation.

  3. Self-assembled ZnO agave-like nanowires and anomalous superhydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y H; Li, Z Y; Wang, B; Wang, C X; Chen, D H; Yang, G W [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics Science and Engineering, Zhongshan University, Guangzhou 510275 (China)

    2005-09-07

    Thin films of ZnO agave-like nanowires were prepared on amorphous carbon thin layers on silicon substrates using thermal chemical vapour transport and condensation without any metal catalysts. The unusual superhydrophobicity of the fabricated surface was measured; the water contact angle reaches 151.1 deg. On the basis of experimental and theoretical analyses, it appears likely that the biomimetic microcomposite and nanocomposite surfaces of the prepared thin films of ZnO agave-like nanowires are responsible for the excellent superhydrophobicity.

  4. Self-assembled ZnO agave-like nanowires and anomalous superhydrophobicity

    Science.gov (United States)

    Yang, Y. H.; Li, Z. Y.; Wang, B.; Wang, C. X.; Chen, D. H.; Yang, G. W.

    2005-09-01

    Thin films of ZnO agave-like nanowires were prepared on amorphous carbon thin layers on silicon substrates using thermal chemical vapour transport and condensation without any metal catalysts. The unusual superhydrophobicity of the fabricated surface was measured; the water contact angle reaches 151.1°. On the basis of experimental and theoretical analyses, it appears likely that the biomimetic microcomposite and nanocomposite surfaces of the prepared thin films of ZnO agave-like nanowires are responsible for the excellent superhydrophobicity.

  5. Self-assembled, nanowire network electrodes for depleted bulk heterojunction solar cells

    KAUST Repository

    Lan, Xinzheng

    2013-01-06

    Herein, a solution-processed, bottom-up-fabricated, nanowire network electrode is developed. This electrode features a ZnO template which is converted into locally connected, infiltratable, TiO2 nanowires. This new electrode is used to build a depleted bulk heterojunction solar cell employing hybrid-passivated colloidal quantum dots. The new electrode allows the application of a thicker, and thus more light-absorbing, colloidal quantum dot active layer, from which charge extraction of an efficiency comparable to that obtained from a thinner, planar device could be obtained. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Surface-confined assemblies and polymers for molecular logic.

    Science.gov (United States)

    de Ruiter, Graham; van der Boom, Milko E

    2011-08-16

    Stimuli responsive materials are capable of mimicking the operation characteristics of logic gates such as AND, OR, NOR, and even flip-flops. Since the development of molecular sensors and the introduction of the first AND gate in solution by de Silva in 1993, Molecular (Boolean) Logic and Computing (MBLC) has become increasingly popular. In this Account, we present recent research activities that focus on MBLC with electrochromic polymers and metal polypyridyl complexes on a solid support. Metal polypyridyl complexes act as useful sensors to a variety of analytes in solution (i.e., H(2)O, Fe(2+/3+), Cr(6+), NO(+)) and in the gas phase (NO(x) in air). This information transfer, whether the analyte is present, is based on the reversible redox chemistry of the metal complexes, which are stable up to 200 °C in air. The concurrent changes in the optical properties are nondestructive and fast. In such a setup, the input is directly related to the output and, therefore, can be represented by one-input logic gates. These input-output relationships are extendable for mimicking the diverse functions of essential molecular logic gates and circuits within a set of Boolean algebraic operations. Such a molecular approach towards Boolean logic has yielded a series of proof-of-concept devices: logic gates, multiplexers, half-adders, and flip-flop logic circuits. MBLC is a versatile and, potentially, a parallel approach to silicon circuits: assemblies of these molecular gates can perform a wide variety of logic tasks through reconfiguration of their inputs. Although these developments do not require a semiconductor blueprint, similar guidelines such as signal propagation, gate-to-gate communication, propagation delay, and combinatorial and sequential logic will play a critical role in allowing this field to mature. For instance, gate-to-gate communication by chemical wiring of the gates with metal ions as electron carriers results in the integration of stand-alone systems: the

  7. Surface-confined assemblies and polymers for molecular logic.

    Science.gov (United States)

    de Ruiter, Graham; van der Boom, Milko E

    2011-08-16

    Stimuli responsive materials are capable of mimicking the operation characteristics of logic gates such as AND, OR, NOR, and even flip-flops. Since the development of molecular sensors and the introduction of the first AND gate in solution by de Silva in 1993, Molecular (Boolean) Logic and Computing (MBLC) has become increasingly popular. In this Account, we present recent research activities that focus on MBLC with electrochromic polymers and metal polypyridyl complexes on a solid support. Metal polypyridyl complexes act as useful sensors to a variety of analytes in solution (i.e., H(2)O, Fe(2+/3+), Cr(6+), NO(+)) and in the gas phase (NO(x) in air). This information transfer, whether the analyte is present, is based on the reversible redox chemistry of the metal complexes, which are stable up to 200 °C in air. The concurrent changes in the optical properties are nondestructive and fast. In such a setup, the input is directly related to the output and, therefore, can be represented by one-input logic gates. These input-output relationships are extendable for mimicking the diverse functions of essential molecular logic gates and circuits within a set of Boolean algebraic operations. Such a molecular approach towards Boolean logic has yielded a series of proof-of-concept devices: logic gates, multiplexers, half-adders, and flip-flop logic circuits. MBLC is a versatile and, potentially, a parallel approach to silicon circuits: assemblies of these molecular gates can perform a wide variety of logic tasks through reconfiguration of their inputs. Although these developments do not require a semiconductor blueprint, similar guidelines such as signal propagation, gate-to-gate communication, propagation delay, and combinatorial and sequential logic will play a critical role in allowing this field to mature. For instance, gate-to-gate communication by chemical wiring of the gates with metal ions as electron carriers results in the integration of stand-alone systems: the

  8. Nanoparticle Self-Assembly in a Polymer Matrix and Its Impact on Phase Separation

    Science.gov (United States)

    Douglas, Jack

    2011-03-01

    The ubiquitous clustering of nanoparticles (NPs) in solutions and polymer melts depends sensitively on the strength and directionality of the effective NP-NP interactions, as well as on the molecular geometry and interactions of the dispersing fluid. Surface functionalization apparently can also lead to emergent anisotropic interactions that can influence NP dispersion. Since NP clustering can strongly influence the properties of polymer nanocomposites and NP solutions, we investigate the reversible self-assembly of model NPs into clusters under equilibrium conditions through a combination of simulation and analytic methods. First, we performed molecular dynamics simulations of polyhedral NPs in a coarse-grained dense bead--spring polymer melt and find a transition from a dispersed to clustered NP state, consistent with the thermodynamic models of equilibrium particle association such as equilibrium polymerization. We also describe the competition between self-assembly and phase separation in an analytic lattice model of a mixture of polymers and NPs. We then focus on the particularly interesting situation where the associating ``monomeric'' NP species form high molecular mass dynamic polymeric clusters and where the assembly process then transforms the phase boundary from a form typical of a polymer solution to one that more resembles a polymer blend with increasing association near the critical point for phase separation. The model calculations elucidate basic physical principles governing the coupling of self-assembly and phase behavior in these complex mixtures.

  9. Understanding Molecular Interactions within Chemically Selective Layered Polymer Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Gary J. Blanchard

    2009-06-30

    This work focuses on two broad issues. These are (1) the molecular origin of the chemical selectivity achieved with ultrathin polymer multilayers, and (2) how the viscoelastic properties of the polymer layers are affected by exposure to solvent and analytes. These issues are inter-related, and to understand them we need to design experiments that probe both the energetic and kinetic aspects of interfacial adsorption processes. This project focuses on controling the chemical structure, thickness, morphology and sequential ordering of polymer layers bound to interfaces using maleimide-vinyl ether and closely related alternating copolymerization chemistry and efficient covalent cross-linking reactions that allow for layer-by-layer polymer deposition. This chemistry has been developed during the funding cycle of this Grant. We have measure the equilibrium constants for interactions between specific layers within the polymer interfaces and size-controlled, surface-functionalized gold nanoparticles. The ability to control both size and functionality of gold nanoparticle model analytes allows us to evaluate the average “pore size” that characterizes our polymer films. We have measured the “bulk” viscosity and shear modulus of the ultrathin polymer films as a function of solvent overlayer identity using quartz crystal microbalance complex impedance measurements. We have measured microscopic viscosity at specific locations within the layered polymer interfaces with time-resolved fluorescence lifetime and depolarization techniques. We combine polymer, cross-linking and nanoparticle synthetic expertise with a host of characterization techniques, including QCM gravimetry and complex impedance analysis, steady state and time-resolved spectroscopies.

  10. Thermally Induced Charge Reversal of Layer-by-Layer Assembled Single-Component Polymer Films.

    Science.gov (United States)

    Richardson, Joseph J; Tardy, Blaise L; Ejima, Hirotaka; Guo, Junling; Cui, Jiwei; Liang, Kang; Choi, Gwan H; Yoo, Pil J; De Geest, Bruno G; Caruso, Frank

    2016-03-23

    Temperature can be harnessed to engineer unique properties for materials useful in various contexts and has been shown to affect the layer-by-layer (LbL) assembly of polymer thin films and cause physical changes in preassembled polymer thin films. Herein we demonstrate that exposure to relatively low temperatures (≤ 100 °C) can induce physicochemical changes in cationic polymer thin films. The surface charge of polymer films containing primary and secondary amines reverses after heating (from positive to negative), and different characterization techniques are used to show that the change in surface charge is related to oxidation of the polymer that specifically occurs in the thin film state. This charge reversal allows for single-polymer LbL assembly to be performed with poly(allylamine) hydrochloride (PAH) through alternating heat/deposition steps. Furthermore, the negative charge induced by heating reduces the fouling and cell-association of PAH-coated planar and particulate substrates, respectively. This study highlights a unique property of thin films which is relevant to LbL assembly and biofouling and is of interest for the future development of thin polymer films for biomedical systems. PMID:26953514

  11. Sensitive pseudobienzyme electrocatalytic DNA biosensor for mercury(II) ion by using the autonomously assembled hemin/G-quadruplex DNAzyme nanowires for signal amplification

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yali [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); College of resources and environments, Southwest University, Chongqing 400715 (China); Gao, Min [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Liu, Guangpeng [College of resources and environments, Southwest University, Chongqing 400715 (China); Chai, Yaqin [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Wei, Shiqing, E-mail: sqwei@swu.edu.cn [College of resources and environments, Southwest University, Chongqing 400715 (China); Yuan, Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2014-02-06

    Graphical abstract: -- Highlights: •An ultrasensitive detection system for Hg{sup 2+} detection was presented. •The autonomously assembled hemin/G-quadruplex DNAzyme nanowires were employed. •The DNAzyme simultaneously served as an NADH oxidase and HRP-mimicking DNAzyme. •The DNAzyme nanowires served as carrier for loading substantial redox probe Thi. -- Abstract: Herein, a novel sensitive pseudobienzyme electrocatalytic DNA biosensor was proposed for mercury ion (Hg{sup 2+}) detection by using autonomously assembled hemin/G-quadruplex DNAzyme nanowires for signal amplification. Thiol functionalized capture DNA was firstly immobilized on a nano-Au modified glass carbon electrode (GCE). In presence of Hg{sup 2+}, the specific coordination between Hg{sup 2+} and T could result in the assembly of primer DNA on the electrode, which successfully triggered the HCR to form the hemin/G-quadruplex DNAzyme nanowires with substantial redox probe thionine (Thi). In the electrolyte of PBS containing NADH, the hemin/G-quadruplex nanowires firstly acted as an NADH oxidase to assist the concomitant formation of H{sub 2}O{sub 2} in the presence of dissolved O{sub 2}. Then, with the redox probe Thi as electron mediator, the hemin/G-quadruplex nanowires acted as an HRP-mimicking DNAzyme that quickly bioelectrocatalyzed the reduction of produced H{sub 2}O{sub 2}, which finally led to a dramatically amplified electrochemical signal. This method has demonstrated a high sensitivity of Hg{sup 2+} detection with the dynamic concentration range spanning from 1.0 ng L{sup −1} to 10 mg L{sup −1} Hg{sup 2+} and a detection limit of 0.5 ng L{sup −1} (2.5 pM) at the 3S{sub blank} level, and it also demonstrated excellent selectivity against other interferential metal ions.

  12. One-step synthesis and patterning of aligned polymer nanowires on a substrate

    Science.gov (United States)

    Wang Zhong L.; Wang, Xudong; Morber, Jenny R.; Liu, Jin

    2011-11-08

    In a method of making a polymer structure on a substrate a layer of a first polymer, having a horizontal top surface, is applied to a surface of the substrate. An area of the top surface of the polymer is manipulated to create an uneven feature that is plasma etched to remove a first portion from the layer of the first polymer thereby leaving the polymer structure extending therefrom. A light emitting structure includes a conductive substrate from which an elongated nanostructure of a first polymer extends. A second polymer coating is disposed about the nanostructure and includes a second polymer, which includes a material such that a band gap exists between the second polymer coating and the elongated nanostructure. A conductive material coats the second polymer coating. The light emitting structure emits light when a voltage is applied between the conductive substrate and the conductive coating.

  13. Crystal Phase Transformation in Self-Assembled InAs Nanowire Junctions on Patterned Si Substrates.

    Science.gov (United States)

    Rieger, Torsten; Rosenbach, Daniel; Vakulov, Daniil; Heedt, Sebastian; Schäpers, Thomas; Grützmacher, Detlev; Lepsa, Mihail Ion

    2016-03-01

    We demonstrate the growth and structural characteristics of InAs nanowire junctions evidencing a transformation of the crystalline structure. The junctions are obtained without the use of catalyst particles. Morphological investigations of the junctions reveal three structures having an L-, T-, and X-shape. The formation mechanisms of these structures have been identified. The NW junctions reveal large sections of zinc blende crystal structure free of extended defects, despite the high stacking fault density obtained in individual InAs nanowires. This segment of zinc blende crystal structure in the junction is associated with a crystal phase transformation involving sets of Shockley partial dislocations; the transformation takes place solely in the crystal phase. A model is developed to demonstrate that only the zinc blende phase with the same orientation as the substrate can result in monocrystalline junctions. The suitability of the junctions to be used in nanoelectronic devices is confirmed by room-temperature electrical experiments. PMID:26881450

  14. Self-assembled growth of GaN nanowires on amorphous Al x O y : from nucleation to the formation of dense nanowire ensembles

    Science.gov (United States)

    Sobanska, M.; Fernández-Garrido, S.; Zytkiewicz, Z. R.; Tchutchulashvili, G.; Gieraltowska, S.; Brandt, O.; Geelhaar, L.

    2016-08-01

    We present a comprehensive description of the self-assembled nucleation and growth of GaN nanowires (NWs) by plasma-assisted molecular beam epitaxy on amorphous Al x O y buffers (a-Al x O y ) prepared by atomic layer deposition. The results are compared with those obtained on nitridated Si(111). Using line-of-sight quadrupole mass spectrometry, we analyze in situ the incorporation of Ga starting from the incubation and nucleation stages till the formation of the final nanowire ensemble and observe qualitatively the same time dependence for the two types of substrates. However, on a-Al x O y the incubation time is shorter and the nucleation faster than on nitridated Si. Moreover, on a-Al x O y we observe a novel effect of decrease in incorporated Ga flux for long growth durations which we explain by coalescence of NWs leading to reduction of the GaN surface area where Ga may reside. Dedicated samples are used to analyze the evolution of surface morphology. In particular, no GaN nuclei are detected when growth is interrupted during the incubation stage. Moreover, for a-Al x O y , the same shape transition from spherical cap-shaped GaN crystallites to the NW-like geometry is found as it is known for nitridated Si. However, while the critical radius for this transition is only slightly larger for a-Al x O y than for nitridated Si, the critical height is more than six times larger for a-Al x O y . Finally, we observe that in fully developed NW ensembles, the substrate no longer influences growth kinetics and the same N-limited axial growth rate is measured on both substrates. We conclude that the same nucleation and growth processes take place on a-Al x O y as on nitridated Si and that these processes are of a general nature. Quantitatively, nucleation proceeds somewhat differently, which indicates the influence of the substrate, but once shadowing limits growth processes to the upper part of the NW ensemble, they are not affected anymore by the type of substrate.

  15. Self-assembled growth of GaN nanowires on amorphous Al x O y : from nucleation to the formation of dense nanowire ensembles.

    Science.gov (United States)

    Sobanska, M; Fernández-Garrido, S; Zytkiewicz, Z R; Tchutchulashvili, G; Gieraltowska, S; Brandt, O; Geelhaar, L

    2016-08-12

    We present a comprehensive description of the self-assembled nucleation and growth of GaN nanowires (NWs) by plasma-assisted molecular beam epitaxy on amorphous Al x O y buffers (a-Al x O y ) prepared by atomic layer deposition. The results are compared with those obtained on nitridated Si(111). Using line-of-sight quadrupole mass spectrometry, we analyze in situ the incorporation of Ga starting from the incubation and nucleation stages till the formation of the final nanowire ensemble and observe qualitatively the same time dependence for the two types of substrates. However, on a-Al x O y the incubation time is shorter and the nucleation faster than on nitridated Si. Moreover, on a-Al x O y we observe a novel effect of decrease in incorporated Ga flux for long growth durations which we explain by coalescence of NWs leading to reduction of the GaN surface area where Ga may reside. Dedicated samples are used to analyze the evolution of surface morphology. In particular, no GaN nuclei are detected when growth is interrupted during the incubation stage. Moreover, for a-Al x O y , the same shape transition from spherical cap-shaped GaN crystallites to the NW-like geometry is found as it is known for nitridated Si. However, while the critical radius for this transition is only slightly larger for a-Al x O y than for nitridated Si, the critical height is more than six times larger for a-Al x O y . Finally, we observe that in fully developed NW ensembles, the substrate no longer influences growth kinetics and the same N-limited axial growth rate is measured on both substrates. We conclude that the same nucleation and growth processes take place on a-Al x O y as on nitridated Si and that these processes are of a general nature. Quantitatively, nucleation proceeds somewhat differently, which indicates the influence of the substrate, but once shadowing limits growth processes to the upper part of the NW ensemble, they are not affected anymore by the type of substrate.

  16. Drug conjugation to cyclic peptide-polymer self-assembling nanotubes.

    Science.gov (United States)

    Blunden, Bianca M; Chapman, Robert; Danial, Maarten; Lu, Hongxu; Jolliffe, Katrina A; Perrier, Sébastien; Stenzel, Martina H

    2014-09-26

    We show for the first time how polymeric nanotubes (NTs) based on self-assembled conjugates of polymers and cyclic peptides can be used as an efficient drug carrier. RAPTA-C, a ruthenium-based anticancer drug, was conjugated to a statistical co-polymer based on poly(2-hydroxyethyl acrylate) (pHEA) and poly(2-chloroethyl methacrylate) (pCEMA), which formed the shell of the NTs. Self-assembly into nanotubes (length 200-500 nm) led to structures exhibiting high activity against cancer cells.

  17. The magnetic assembly of polymer colloids in a ferrofluid and its display applications.

    Science.gov (United States)

    Liu, Jing; Mao, Yiwu; Ge, Jianping

    2012-03-01

    Nonmagnetic polymer colloids have been assembled into colloidal photonic crystals in a ferrofluid by applying an external magnetic field based on the dipole-dipole interactions of "magnetic holes". The photonic crystal disassembles immediately when the magnetic field is removed. The mechanism of assembly can be explained by two simultaneous processes: phase separation and colloidal assembly. In this work, increasing the size of the building blocks still produces colorful photonic crystals due to their 2nd order diffraction. With a larger building block, the magnetic response between the polymer colloids is greatly enhanced so that an instant and reversible assembly/disassembly can be realized in a much weaker magnetic field and lower ferrofluid concentration. Based on these investigations, a magnetically controlled photonic display unit has been fabricated, which works in a weak magnetic field, has stable reflection signals and possesses fast and reversible on/off switching of reflections. PMID:22297654

  18. Self-Assembling Peptide-Polymer Hydrogels Designed From the Coiled Coil Region of Fibrin

    OpenAIRE

    Jing, Peng; Rudra, Jai S; Herr, Andrew B.; Collier, Joel H.

    2008-01-01

    Biomaterials constructed from self-assembling peptides, peptide derivatives, and peptide-polymer conjugates are receiving increasing attention as defined matrices for tissue engineering, controlled therapeutic release, and in vitro cell expansion, but many are constructed from peptide structures not typically found in the human extracellular matrix. Here we report a self-assembling biomaterial constructed from a designed peptide inspired by the coiled coil domain of human fibrin, the major pr...

  19. Virus-Assembled Flexible Electrode-Electrolyte Interfaces for Enhanced Polymer-Based Battery Applications

    OpenAIRE

    Ayan Ghosh; Juchen Guo; Brown, Adam D; Elizabeth Royston; Chunsheng Wang; Peter Kofinas; Culver, James N.

    2012-01-01

    High-aspect-ratio cobalt-oxide-coated Tobacco mosaic virus (TMV-) assembled polytetrafluoroethylene (PTFE) nonstick surfaces were integrated with a solvent-free polymer electrolyte to create an anode-electrolyte interface for use in lithium-ion batteries. The virus-assembled PTFE surfaces consisted primarily of cobalt oxide and were readily intercalated with a low-molecular-weight poly (ethylene oxide) (PEO) based diblock copolymer electrolyte to produce a solid anode-electrolyte system. The ...

  20. Development of palladium nanowires

    Science.gov (United States)

    Cheng, Chuanding

    Inherent limitations of traditional lithography have prompted the search for means of achieving self-assembly of nano-scale structures and networks for the next generation of electronic and photonic devices. The nanowire, the basic building block of a nanocircuit, has recently become the focus of intense research. Reports on nanowire synthesis and assembly have appeared in the scientific literature, which include Vapor-Liquid-Solid mechanism, template-based electrochemical fabrication, solvothermal or wet chemistry, and assembly by fluid alignment or microchannel networks. An ideal approach for practical application of nanowires would circumvent technical and economic constraints of templating. Here we report on the self-assembly of highly-ordered metallic nanowires directly from a palladium acetate solution under an applied alternating current (AC) electric field of relatively high intensity and frequency. DNA-templated nanowires are first presented here. DNA molecules were stretched and positioned by electric field, followed by metallization by palladium acetate solution. Palladium nanowire arrays have been found to grow directly between microelectrodes without any template, under an alternating electric field of relatively high intensity and frequency. The wires grew spontaneously along the direction of the electric field and have high uniformity and conductivity. Single 75 nm-diameter palladium nanowires have also been self-assembled from aqueous solution at predefined locations between 15 mum-gap electrodes built on a SiO2 substrate. Nanowire assembly was initiated by application an electric field, and it occurred only along the direction of field lines where the field is strongest. Related metals did not support single nanowire assembly under comparable conditions. Current-limiting circuits for controlled nanowire synthesis, electric field simulation, and growth mechanism were studied. The simple and straightforward approach to nanowire assembly outlined here

  1. Polymer lasers assembled by suspending membranes on a distributed feedback grating.

    Science.gov (United States)

    Zhai, Tianrui; Tong, Fei; Wang, Yonglu; Wu, Xiaofeng; Li, Songtao; Wang, Meng; Zhang, Xinping

    2016-09-19

    Polymer lasers are fabricated by an assembly method. A polymer membrane is directly attached on the one- or two- dimensional grating. The suspended membrane acts as an active waveguide, which is supported by the grating ridge, leaving air gaps in the grating valley. Most of the radiation is effectively confined within the active waveguide due to the strong reflection at the membrane/air interfaces. So, low threshold lasing can be achieved when the sample is optically pumped. This fabrication method provides an alternative to investigate low-threshold polymer lasers. PMID:27661937

  2. Roll-to-Roll Printed Silver Nanowire Semitransparent Electrodes for Fully Ambient Solution-Processed Tandem Polymer Solar Cells

    DEFF Research Database (Denmark)

    Angmo, Dechan; Andersen, Thomas Rieks; Bentzen, Janet Jonna;

    2015-01-01

    Silver nanowires (AgNWs) and zinc oxide (ZnO) are deposited on flexible substrates using fast roll-to-roll (R2R) processing. The AgNW film on polyethylene terephthalate (PET) shows >80% uniform optical transmission in the range of 550-900 nm. This electrode is compared to the previously reported...... and currently widely produced indium-tin-oxide (ITO) replacement comprising polyethylene terephthalate (PET)|silver grid|poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)|ZnO known as Flextrode. The AgNW/ZnO electrode shows higher transmission than Flextrode above 490 nm in the electromagnetic...... spectrum reaching up to 40% increased transmission at 750 nm in comparison to Flextrode. The functionality of AgNW electrodes is demonstrated in single and tandem polymer solar cells and compared with parallel devices on traditional Flextrode. All layers, apart from the semitransparent electrodes which...

  3. Synthesis, characterisation and electrical properties of supramolecular DNA-templated polymer nanowires of 2,5-(bis-2-thienyl)-pyrrole.

    Science.gov (United States)

    Watson, Scott M D; Hedley, Joseph H; Galindo, Miguel A; Al-Said, Said A F; Wright, Nick G; Connolly, Bernard A; Horrocks, Benjamin R; Houlton, Andrew

    2012-09-17

    Supramolecular polymer nanowires have been prepared by using DNA-templating of 2,5-(bis-2-thienyl)-pyrrole (TPT) by oxidation with FeCl(3) in a mixed aqueous/organic solvent system. Despite the reduced capacity for strong hydrogen bonding in polyTPT compared to other systems, such as polypyrrole, the templating proceeds well. FTIR spectroscopic studies confirm that the resulting material is not a simple mixture and that the two types of polymer interact. This is indicated by shifts in bands associated with both the phosphodiester backbone and the nucleobases. XPS studies further confirm the presence of DNA and TPT, as well as dopant Cl(-) ions. Molecular dynamics simulations on a [{dA(24):dT(24)}/{TPT}(4)] model support these findings and indicate a non-coplanar conformation for oligoTPT over much of the trajectory. AFM studies show that the resulting nanowires typically lie in the 7-8 nm diameter range and exhibit a smooth, continuous, morphology. Studies on the electrical properties of the prepared nanowires by using a combination of scanned conductance microscopy, conductive AFM and variable temperature two-terminal I-V measurements show, that in contrast to similar DNA/polymer systems, the conductivity is markedly reduced compared to bulk material. The temperature dependence of the conductivity shows a simple Arrhenius behaviour consistent with the hopping models developed for redox polymers.

  4. Assembly of optical fibers for the connection of polymer-based waveguide

    Science.gov (United States)

    Ansel, Yannick; Grau, Daniel; Holzki, Markus; Kraus, Silvio; Neumann, Frank; Reinhard, Carsten; Schmitz, Felix

    2003-03-01

    This paper describes the realization of polymer-based optical structures and the assembly and packaging strategy to connect optical fiber ribbons to the waveguides. For that a low cost fabrication process using the SU-8TM thick photo-resist is presented. This process consists in the deposition of two photo-structurized resist layers filled up with epoxy glue realising the core waveguide. For the assembly, a new modular vacuum gripper was realised and installed on an automatic pick and place assembly robot to mount precisely and efficiently the optical fibers in the optical structures. First results have shown acceptable optical propagation loss for the complete test structure.

  5. Controlled Self Assembly of Conjugated Polymer Containing Block Copolymers

    OpenAIRE

    McCulloch, Bryan

    2012-01-01

    The discovery and development of conjugated polymers has led to a large and vibrant research field due to their unique semiconducting properties and possibility of offering a completely new paradigm due to their abundant, lightweight, flexible and solution processable properties. In particular, the optoelectronic properties of these materials make them very well suited to applications such as organic light emitting diodes or organic photovoltaics and their relatively high charge mobility als...

  6. Self-assembly in a polymer matrix and its impact on phase separation.

    Science.gov (United States)

    Dudowicz, Jacek; Douglas, Jack F; Freed, Karl F

    2009-03-26

    Molecular self-assembly often occurs in the presence of long chain polymers, and we develop a theory to describe the competition between self-assembly and phase separation that generally occurs in these complex fluid mixtures. The theory includes a description of the particularly interesting situation where the associating "monomeric" species form high molecular mass polymeric structures and where the assembly process transforms the phase boundary from a form typical of a polymer solution to one that more resembles a polymer blend. We consider both self-assembly upon cooling and upon heating, but the van der Waals interactions are chosen so that phase separation occurs only upon cooling in the absence of association. Systems that associate upon heating prove to be particularly rich, and closed loop and ordinary (upper solution critical) phase boundaries are found to coexist over a wide range of interaction parameter values. Each critical temperature in the limit of a large polymerization index for the matrix polymers approaches its respective theta temperature. The calculations elucidate basic physical principles governing the phase behavior of these complex mixtures.

  7. Tuning the Assembly of Spherical Nanoparticles in Semicrystalline Polymers

    Science.gov (United States)

    Zhao, Dan; Jestin, Jacques; Zhao, Longxi; Kumar, Sanat K.; Mohammadkhani, Mohammad; Benicewicz, Brian C.

    We propose a simple, novel strategy to controlling nanoparticle (NPs) dispersion states in a semi-crystalline polymer matrix exploiting the kinetics of polymer crystallization. The system consists of poly(methyl methacrylate) grafted spherical silica NPs and poly(ethylene oxide) matrices, which are thermodynamically miscible in the melt. We first show that no remarkable change was observed in the spatial dispersion of NPs upon fast crystallization. However, for slow crystallization, both TEM and X-ray/neutron scattering reveal that the system starts to be organized in a ``layer-by-layer'' architecture, where the NPs are aligned in the amorphous phases intercalated by the crystalline lamellar phases. More importantly, we have found that the resulting ``sheet-like'' NP morphology gives rise to a 2-fold increase in the storage modulus but without compromising the fracture toughness of the neat polymer. These results open pathways for creating in-situ biomimetic hierarchical structures with improved mechanical properties through a simple, single-step crystallization processing, which could lead to new applications for this largest class of commercially relevant polymeric materials.

  8. Ultrathin Nanotube/Nanowire Electrodes by Spin-Spray Layer-by-Layer Assembly: A Concept for Transparent Energy Storage.

    Science.gov (United States)

    Gittleson, Forrest S; Hwang, Daniel; Ryu, Won-Hee; Hashmi, Sara M; Hwang, Jonathan; Goh, Tenghooi; Taylor, André D

    2015-10-27

    Fully integrated transparent devices require versatile architectures for energy storage, yet typical battery electrodes are thick (20-100 μm) and composed of optically absorbent materials. Reducing the length scale of active materials, assembling them with a controllable method and minimizing electrode thickness should bring transparent batteries closer to reality. In this work, the rapid and controllable spin-spray layer-by-layer (SSLbL) method is used to generate high quality networks of 1D nanomaterials: single-walled carbon nanotubes (SWNT) and vanadium pentoxide (V2O5) nanowires for anode and cathode electrodes, respectively. These ultrathin films, deposited with ∼2 nm/bilayer precision are transparent when deposited on a transparent substrate (>87% transmittance) and electrochemically active in Li-ion cells. SSLbL-assembled ultrathin SWNT anodes and V2O5 cathodes exhibit reversible lithiation capacities of 23 and 7 μAh/cm(2), respectively at a current density of 5 μA/cm(2). When these electrodes are combined in a full cell, they retain ∼5 μAh/cm(2) capacity over 100 cycles, equivalent to the prelithiation capacity of the limiting V2O5 cathode. The SSLbL technique employed here to generate functional thin films is uniquely suited to the generation of transparent electrodes and offers a compelling path to realize the potential of fully integrated transparent devices. PMID:26344174

  9. Electrostatically Directed Self-Assembly of Ultrathin Supramolecular Polymer Microcapsules

    OpenAIRE

    Parker, Richard M.; Zhang, Jing; Zheng, Yu; Coulston, Roger J.; Smith, Clive A; Salmon, Andrew R; Yu, Ziyi; Oren A. Scherman; Abell, Chris

    2015-01-01

    Supramolecular self-assembly offers routes to challenging architectures on the molecular and macroscopic scale. Coupled with microfluidics it has been used to make microcapsules—where a 2D sheet is shaped in 3D, encapsulating the volume within. In this paper, a versatile methodology to direct the accumulation of capsule-forming components to the droplet interface using electrostatic interactions is described. In this approach, charged copolymers are selectively partitioned to the microdroplet...

  10. Tuning the sphere-to-rod transition in the self-assembly of thermoresponsive polymer hybrids.

    Science.gov (United States)

    Lee, Jangwook; Park, Honghyun; Jeong, Eun Ju; Kwark, Young-Je; Lee, Kuen Yong

    2015-12-01

    Nano-scale drug delivery systems have undergone extensive development, and control of size and structure is critical for regulation of their biological responses and therapeutic efficacy. Amphiphilic polymers that form self-assembled structures in aqueous media have been investigated and used for the diagnosis and therapy of various diseases, including cancer. Here, we report the design and fabrication of thermoresponsive polymeric micelles from alginate conjugated with poly(N-isopropylacrylamide) (PNIPAAm). Alginate-PNIPAAm hybrids formed self-aggregated structures in response to temperature changes near body temperature. A structural transition from micellar spheres to rods of alginate-PNIPAAm hybrids was observed depending on the molecular weight of PNIPAAm and the polymer concentration. Additionally, hydrogels with nanofibrous structures were formed by simply increasing the polymer concentration. This approach to controlling the structure of polymer micelles from nanoparticles to fibrous hydrogels may be useful in applications in drug delivery and tissue engineering.

  11. ZnO nanowire network transistors based on a self-assembly method

    Institute of Scientific and Technical Information of China (English)

    Dai Zhenqing; Chen Changxin; Zhang Yaozhong; Wei Liangming; Zhang Jing; Xu Dong; Zhang Yafei

    2012-01-01

    Dense,uniform ZnO nanowire (NW) networks are prepared by using a simple and sufficient selfassembly method.In this method,ZnO NWs are modified with aminopropyltriethoxysilane (APTES) to form positively charged amine-terminated surfaces.The modified ZnO NWs are adsorbed on negatively charged SiO2/Si substrates to form ZnO NW networks by the electrostatic interaction in an aqueous solution.Field-effect transistors (FETs) are fabricated and studied based on the ZnO NW networks.For a typical device with an NW density of 2.8 μm-2,it exhibits a current on/off ratio of 2.4 × 105,a transconductance of 336 nS,and a field-effect mobility of 27.4 cm2/(V·s).

  12. Effect of polymer brushes on the Self Assembly of 3D Poly(Styrene-Methylmethacrylate) thin films

    Science.gov (United States)

    Lwoya, Baraka; Albert, Julie

    2015-03-01

    It would be instrumental to understand the self-assembly capabilities of polymers especially given their industrial capabilities of templating and membrane application .The ability of block copolymers to self assemble into different morphologies is determined by several factor including type of polymer blocks, volume fraction, substrate preference to a polymer and chain architecture . In this paper Poly(Styrene-Methylmethacrylate) (PS-PMMA) was chosen was chosen to further understand the effect polymer brushes on the substrate had on the self assembly of 3D structured PS-PMMA spin coated thin films (30-150 nm). The polymer brushes were grown using surface initiated atomic transfer radical polymerization (SI-ATRP) with the optimal chain length being confirmed by gel permeation chromatography. By using ellipsometer and contact angle measurement the uniformity of the polymer brushes are characterized, while the morphology of the spin coated thin films after thermal annealing would be characterized using atomic force microscopy (AFM).

  13. Polymer-mediated nanorod self-assembly predicted by dissipative particle dynamics simulations.

    Science.gov (United States)

    Khani, Shaghayegh; Jamali, Safa; Boromand, Arman; Hore, Michael J A; Maia, Joao

    2015-09-14

    Self-assembly of nanoparticles in polymer matrices is an interesting and growing subject in the field of nanoscience and technology. We report herein on modelling studies of the self-assembly and phase behavior of nanorods in a homopolymer matrix, with the specific goal of evaluating the role of deterministic entropic and enthalpic factors that control the aggregation/dispersion in such systems. Grafting polymer brushes from the nanorods is one approach to control/impact their self-assembly capabilities within a polymer matrix. From an energetic point of view, miscible interactions between the brush and the matrix are required for achieving a better dispersibility; however, grafting density and brush length are the two important parameters in dictating the morphology. Unlike in previous computational studies, the present Dissipative Particle Dynamics (DPD) simulation framework is able to both predict dispersion or aggregation of nanorods and determine the self-assembled structure, allowing for the determination of a phase diagram, which takes all of these factors into account. Three types of morphologies are predicted: dispersion, aggregation and partial aggregation. Moreover, favorable enthalpic interactions between the brush and the matrix are found to be essential for expanding the window for achieving a well-dispersed morphology. A three-dimensional phase diagram is mapped on which all the afore-mentioned parameters are taken into account. Additionally, in the case of immiscibility between brushes and the matrix, simulations predict the formation of some new and tunable structures.

  14. Polymer-mediated nanorod self-assembly predicted by dissipative particle dynamics simulations.

    Science.gov (United States)

    Khani, Shaghayegh; Jamali, Safa; Boromand, Arman; Hore, Michael J A; Maia, Joao

    2015-09-14

    Self-assembly of nanoparticles in polymer matrices is an interesting and growing subject in the field of nanoscience and technology. We report herein on modelling studies of the self-assembly and phase behavior of nanorods in a homopolymer matrix, with the specific goal of evaluating the role of deterministic entropic and enthalpic factors that control the aggregation/dispersion in such systems. Grafting polymer brushes from the nanorods is one approach to control/impact their self-assembly capabilities within a polymer matrix. From an energetic point of view, miscible interactions between the brush and the matrix are required for achieving a better dispersibility; however, grafting density and brush length are the two important parameters in dictating the morphology. Unlike in previous computational studies, the present Dissipative Particle Dynamics (DPD) simulation framework is able to both predict dispersion or aggregation of nanorods and determine the self-assembled structure, allowing for the determination of a phase diagram, which takes all of these factors into account. Three types of morphologies are predicted: dispersion, aggregation and partial aggregation. Moreover, favorable enthalpic interactions between the brush and the matrix are found to be essential for expanding the window for achieving a well-dispersed morphology. A three-dimensional phase diagram is mapped on which all the afore-mentioned parameters are taken into account. Additionally, in the case of immiscibility between brushes and the matrix, simulations predict the formation of some new and tunable structures. PMID:26235000

  15. Hybrid Materials Prepared from Polymers and Self-assembled Systems by Physical Processes

    Institute of Scientific and Technical Information of China (English)

    Jean-Michel; Guenet

    2007-01-01

    1 Results A new type of hybrid materails prepared from ternary systems polymer/bicopper organic complex/solvent is presented.Each binary system displays differing types of behaviour: The polymer solutions produce thermoreversible gels while the bicopper organic complex (designated as CuS8) forms randomly-dispersed,self-assembling threads in organic solvents (See Fig.1(a),(b)).Fig.1 The CuS8 and ips thermoreversible gels Thermoreversible gels possess a fibrillar morphology with a typical mesh size ra...

  16. Ordered silicon nanowire arrays prepared by an improved nanospheres self-assembly in combination with Ag-assisted wet chemical etching

    Science.gov (United States)

    Jia, Guobin; Westphalen, Jasper; Drexler, Jan; Plentz, Jonathan; Dellith, Jan; Dellith, Andrea; Andrä, Gudrun; Falk, Fritz

    2016-04-01

    An improved Langmuir-Blodgett self-assembly process combined with Ag-assisted wet chemical etching for the preparation of ordered silicon nanowire arrays is presented in this paper. The new process is independent of the surface conditions (hydrophilic or hydrophobic) of the substrate, allowing for depositing a monolayer of closely packed polystyrene nanospheres onto any flat surface. A full control of the morphology of the silicon nanowire is achieved. Furthermore, it is observed that the formation of porous-Si at the tips of the nanowires is closely related to the release of Ag nanoparticles from the Ag mask during the etching, which subsequently redeposit on the surface initially free of Ag, and these Ag nanoparticles catalyze the etching of the tips and lead to the porous-Si formation. This finding will help to improve the resulting nano- and microstructures to get them free of pores, and renders it a promising technology for low-cost high throughput fabrication of specific optical devices, photonic crystals, sensors, MEMS, and NEMS by substituting the costly BOSCH process. It is shown that ordered nanowire arrays free of porous structures can be produced if all sources of Ag nanoparticles are excluded, and structures with aspect ratio more than 100 can be produced.

  17. High-performance ambipolar self-assembled Au/Ag nanowire based vertical quantum dot field effect transistor.

    Science.gov (United States)

    Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Wang, Jianlong; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

    2016-10-01

    Most lateral PbSe quantum dot field effect transistors (QD FETs) show a low on current/off current (I on/I off) ratio in charge transport measurements. A new strategy to provide generally better performance is to design PbSe QD FETs with vertical architecture, in which the structure parameters can be tuned flexibly. Here, we fabricated a novel room-temperature operated vertical quantum dot field effect transistor with a channel of 580 nm, where self-assembled Au/Ag nanowires served as source transparent electrodes and PbSe quantum dots as active channels. Through investigating the electrical characterization, the ambipolar device exhibited excellent characteristics with a high I on/I off current ratio of about 1 × 10(5) and a low sub-threshold slope (0.26 V/decade) in the p-type regime. The all-solution processing vertical architecture provides a convenient way for low cost, large-area integration of the device. PMID:27578613

  18. High-performance ambipolar self-assembled Au/Ag nanowire based vertical quantum dot field effect transistor

    Science.gov (United States)

    Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Wang, Jianlong; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

    2016-10-01

    Most lateral PbSe quantum dot field effect transistors (QD FETs) show a low on current/off current (I on/I off) ratio in charge transport measurements. A new strategy to provide generally better performance is to design PbSe QD FETs with vertical architecture, in which the structure parameters can be tuned flexibly. Here, we fabricated a novel room-temperature operated vertical quantum dot field effect transistor with a channel of 580 nm, where self-assembled Au/Ag nanowires served as source transparent electrodes and PbSe quantum dots as active channels. Through investigating the electrical characterization, the ambipolar device exhibited excellent characteristics with a high I on/I off current ratio of about 1 × 105 and a low sub-threshold slope (0.26 V/decade) in the p-type regime. The all-solution processing vertical architecture provides a convenient way for low cost, large-area integration of the device.

  19. Gallium-Catalyzed Silicon Oxide Nanowire Growth

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei Pan; Sheng Dai; Douglas H.Lowndes

    2005-01-01

    Silicon oxide nanowires tend to assemble into various complex morphologies through a metalcatalyzed vapor-liquid-solid (VLS) growth process. This article summarizes our recent efforts in the controlled growth of silicon oxide nanowire assemblies by using molten gallium as the catalyst and silicon wafer,SiO powder, or silane (SiH4) as the silicon sources. Silicon oxide nanowire assemblies with morphologies of carrotlike, cometlike, gourdlike, spindlelike, badmintonlike, sandwichlike, etc. were obtained. Although the morphologies of the nanowire assemblies are temperature- and silicon source-dependent, they share similar structural and compositional features: all the assemblies contain a microscale spherical liquid Ga ball and a highly aligned, closely packed amorphous silicon oxide nanowire bunch. The Ga-catalyzed silicon oxide nanowire growth reveals several interesting new nanowire growth phenomena that expand our knowledge of the conventional VLS nanowire growth mechanism.

  20. Polymer Directed Self-Assembly of pH-Responsive Antioxidant Nanoparticles

    Science.gov (United States)

    Tang, Christina; Amin, Devang; Messersmith, Phillip B.; Anthony, John E.; Prud’homme, Robert K.

    2015-01-01

    We have developed pH-responsive, multifunctional nanoparticles based on encapsulation of an antioxidant, tannic acid (TA), using Flash NanoPrecipitation, a polymer directed self-assembly method. Formation of insoluble coordination complexes of tannic acid and iron during mixing drives nanoparticle assembly. Tuning the core material to polymer ratio, the size of the nanoparticles can be readily tuned between 50 and 265 nm. The resulting nanoparticle is pH-responsive, i.e. stable at pH 7.4 and soluble under acidic conditions due to the nature of the coordination complex. Further, the coordination complex can be coprecipitated with other hydrophobic materials such as therapeutics or imaging agents. For example, coprecipitation with a hydrophobic fluorescent dye creates fluorescent nanoparticles. In vitro, the nanoparticles have low cytotoxicity show antioxidant activity. Therefore, these particles may facilitate intracellular delivery of antioxidants. PMID:25760226

  1. Virus-Assembled Flexible Electrode-Electrolyte Interfaces for Enhanced Polymer-Based Battery Applications

    Directory of Open Access Journals (Sweden)

    Ayan Ghosh

    2012-01-01

    Full Text Available High-aspect-ratio cobalt-oxide-coated Tobacco mosaic virus (TMV- assembled polytetrafluoroethylene (PTFE nonstick surfaces were integrated with a solvent-free polymer electrolyte to create an anode-electrolyte interface for use in lithium-ion batteries. The virus-assembled PTFE surfaces consisted primarily of cobalt oxide and were readily intercalated with a low-molecular-weight poly (ethylene oxide (PEO based diblock copolymer electrolyte to produce a solid anode-electrolyte system. The resulting polymer-coated virus-based system was then peeled from the PTFE backing to produce a flexible electrode-electrolyte component. Electrochemical studies indicated the virus-structured metal-oxide PEO-based interface was stable and displayed robust charge transfer kinetics. Combined, these studies demonstrate the development of a novel solid-state electrode architecture with a unique peelable and flexible processing attribute.

  2. Water-Soluble Conjugated Polymers: Self-Assembly and Biosensor Applications

    Science.gov (United States)

    Bazan, Guillermo

    2005-03-01

    Homogeneous assays can be designed which take advantage of the optical amplification of conjugated polymers and the self-assembly characteristic of aqueous polyelectrolytes. For example, a ssDNA sequence sensor comprises an aqueous solution containing a cationic water soluble conjugated polymer such as poly(9,9-bis(trimethylammonium)-hexyl)-fluorene phenylene) with a peptide nucleic acid (PNA) labeled with a dye (PNA-C*). Signal transduction is controlled by hybridization of the neutral PNA-C* probe and the negative ssDNA target, resulting in favorable electrostatic interactions between the hybrid complex and the cationic polymer. Distance requirements for Förster energy transfer are thus met only when ssDNA of complementary sequence to the PNA-C* probe is present. Signal amplification by the conjugated polymer provides fluorescein emission >25 times higher than that of the directly excited dye. Transduction by electrostatic interactions followed by energy transfer is a general strategy. Examples involving other biomolecular recognition events, such as DNA/DNA, RNA/protein and RNA/RNA, will also be provided. The mechanism of biosensing will be discussed, with special attention to the varying contributions of hydrophobic and electrostatic forces, polymer conformation, charge density, local concentration of C*s and tailored defect sites for aggregation-induced optical changes. Finally, the water solubility of these conjugated polymers opens possibilities for spin casting onto organic materials, without dissolving the underlying layers. This property is useful for fabricating multilayer organic optoelectronic devices by simple solution techniques.

  3. Directed Self-Assembly of Block Copolymers for High Breakdown Strength Polymer Film Capacitors.

    Science.gov (United States)

    Samant, Saumil P; Grabowski, Christopher A; Kisslinger, Kim; Yager, Kevin G; Yuan, Guangcui; Satija, Sushil K; Durstock, Michael F; Raghavan, Dharmaraj; Karim, Alamgir

    2016-03-01

    Emerging needs for fast charge/discharge yet high-power, lightweight, and flexible electronics requires the use of polymer-film-based solid-state capacitors with high energy densities. Fast charge/discharge rates of film capacitors on the order of microseconds are not achievable with slower charging conventional batteries, supercapacitors and related hybrid technologies. However, the current energy densities of polymer film capacitors fall short of rising demand, and could be significantly enhanced by increasing the breakdown strength (EBD) and dielectric permittivity (εr) of the polymer films. Co-extruded two-homopolymer component multilayered films have demonstrated much promise in this regard showing higher EBD over that of component polymers. Multilayered films can also help incorporate functional features besides energy storage, such as enhanced optical, mechanical, thermal and barrier properties. In this work, we report accomplishing multilayer, multicomponent block copolymer dielectric films (BCDF) with soft-shear driven highly oriented self-assembled lamellar diblock copolymers (BCP) as a novel application of this important class of self-assembling materials. Results of a model PS-b-PMMA system show ∼50% enhancement in EBD of self-assembled multilayer lamellar BCP films compared to unordered as-cast films, indicating that the breakdown is highly sensitive to the nanostructure of the BCP. The enhancement in EBD is attributed to the "barrier effect", where the multiple interfaces between the lamellae block components act as barriers to the dielectric breakdown through the film. The increase in EBD corresponds to more than doubling the energy storage capacity using a straightforward directed self-assembly strategy. This approach opens a new nanomaterial paradigm for designing high energy density dielectric materials. PMID:26942835

  4. Characterization of Self-Assembly and Charge Transport in Model Polymer Electrolyte Membranes

    OpenAIRE

    Beers, Keith Morgan

    2012-01-01

    There is broad interest in creating polymer electrolyte membranes (PEMs) that have a charged hydrophilic nanophase, where the size and geometry of the phase can be precisely controlled. The applications for such materials range from portable power generating devices to water purification. There is a need to better characterize the self-assembly, thermodynamics, and performance of both current and future PEMs. To this end a series of chapters is presented, that explore the development of techn...

  5. Silicon nanowire hybrid photovoltaics

    KAUST Repository

    Garnett, Erik C.

    2010-06-01

    Silicon nanowire Schottky junction solar cells have been fabricated using n-type silicon nanowire arrays and a spin-coated conductive polymer (PEDOT). The polymer Schottky junction cells show superior surface passivation and open-circuit voltages compared to standard diffused junction cells with native oxide surfaces. External quantum efficiencies up to 88% were measured for these silicon nanowire/PEDOT solar cells further demonstrating excellent surface passivation. This process avoids high temperature processes which allows for low-cost substrates to be used. © 2010 IEEE.

  6. Exploiting Fluorescent Polymers To Probe the Self-Assembly of Virus-like Particles

    DEFF Research Database (Denmark)

    Caden-Nava, Ruben D.; Hu, Yufang; Garmann, Rees F.;

    2011-01-01

    The inside surfaces of the protein shells of many viruses are positively charged, thereby enhancing the self-assembly of capsid proteins around their (oppositely charged) RNA genome. These proteins have been shown to organize similarly around a variety of nonbiological, negatively charged, polyme...... than that of the capsid protein by as much as a factor of 2. VLPs of this kind provide a versatile model system for determining the principles underlying self-assembly of controlled numbers of cargo molecules in nanocontainers of increasing size.......The inside surfaces of the protein shells of many viruses are positively charged, thereby enhancing the self-assembly of capsid proteins around their (oppositely charged) RNA genome. These proteins have been shown to organize similarly around a variety of nonbiological, negatively charged, polymers......), and that the total charge on the PSS exceeds that of the capsid protein by as much as a factor of 9. Here, we extend studies of this kind to PSS molecules that are sufficiently small that two or more can be packaged into VLPs. The use of 38 kDa PSS polymers that have been fluorescently labeled with Rhodamine B...

  7. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui

    2016-07-13

    We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

  8. Modeling the Assembly of Polymer-Grafted Nanoparticles at Oil-Water Interfaces.

    Science.gov (United States)

    Yong, Xin

    2015-10-27

    Using dissipative particle dynamics (DPD), I model the interfacial adsorption and self-assembly of polymer-grafted nanoparticles at a planar oil-water interface. The amphiphilic core-shell nanoparticles irreversibly adsorb to the interface and create a monolayer covering the interface. The polymer chains of the adsorbed nanoparticles are significantly deformed by surface tension to conform to the interface. I quantitatively characterize the properties of the particle-laden interface and the structure of the monolayer in detail at different surface coverages. I observe that the monolayer of particles grafted with long polymer chains undergoes an intriguing liquid-crystalline-amorphous phase transition in which the relationship between the monolayer structure and the surface tension/pressure of the interface is elucidated. Moreover, my results indicate that the amorphous state at high surface coverage is induced by the anisotropic distribution of the randomly grafted chains on each particle core, which leads to noncircular in-plane morphology formed under excluded volume effects. These studies provide a fundamental understanding of the interfacial behavior of polymer-grafted nanoparticles for achieving complete control of the adsorption and subsequent self-assembly. PMID:26439456

  9. Fully Solution-Processed Inverted Polymer Solar Cells with Laminated Nanowire Electrodes

    KAUST Repository

    Gaynor, Whitney

    2010-01-26

    We demonstrate organic photovoltaic cells in which every layer is deposited by solution processing on opaque metal substrates, with efficiencies similar to those obtained in conventional device structures on transparent substrates. The device architecture is enabled by solution-processed, laminated silver nanowire films serving as the top transparent anode. The cells are based on the regioregular poly(3- hexylthiophene) and C 61 butyric acid methyl ester bulk heterojunction and reach an efficiency of 2.5% under 100 mW/cm 2 of AM 1.5G illumination. The metal substrates are adequate barriers to moisture and oxygen, in contrast to transparent plastics that have previously been used, giving rise to the possibility of roll-to-roll solutionprocessed solar cells that are packaged by lamination to glass substrates, combining the cost advantage of roll-toroll processing with the barrier properties of glass and metal foil. © 2010 American Chemical Society.

  10. Electrical Conductivity and Current-Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires

    Institute of Scientific and Technical Information of China (English)

    LONG Yun-Ze; DUVAIL Jean-Luc; CHEN Zhao-Jia; JIN Ai-Zi; GU Chang-Zhi

    2008-01-01

    We report the current-voltage (I-V) characteristics and electrical conductivity of individual template-synthesized poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires (190 ± 6 nm in diameter and σRT : 11.2±2Ω-1cm-1)over a wide temperature range from 300 to 10K. With lowering temperature, the Ⅰ- Ⅴ characteristics become nonlinear around 50 K, and a clear Coulomb gap-like structure appears in the differential conductance (dI/dV)spectra. The temperature dependence of the resistance below 70 K follows ln R ∝ T-1/2, which can be interpreted as Efros-Shklovskii hopping conduction in the presence of a Coulomb gap. In addition, the influences of measurement methods such as the applied bias voltage magnitude, the two-probe and four-probe techniques used in the resistance measurements are also reported and discussed.

  11. A novel self-assembly with zinc porphyrin coordination polymer for enhanced photocurrent conversion in supramolecular solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: An innovative type of self-assembly based on acetohydrazide zinc porphyrin coordination polymer has been prepared in supramolecular solar cells. - Highlights: • A novel assembly with acetohydrazide porphyrin coordination polymer. • The assembly based on porphyrin is prepared as parallel sample. • Coordination polymer-based assembly shows enhanced photoelectronic behavior. • A series of different organic acid ligands as anchoring groups are prepared. - Abstract: In this work, a novel acetohydrazide zinc porphyrin-based coordination polymer (CP)-isonicotinic acid self-assembly by metal-ligand axial coordination to modify the nano-structured TiO2 electrode surface has been investigated in photoelectrochemical device. Compared to the assembly based on corresponding zinc porphyrin combined with isonicotinic acid by metal-ligand axial coordination, CP-isonicotinic acid assembly exhibits a significantly enhanced photoelectronic behavior. In addition, a series of different organic acid ligands were prepared to probe the impact of their structures on the photoelectronic performances of their corresponding assemblies-sensitized cells. This study affords a novel type of self-assembly to functionalize the nanostructured TiO2 electrode surface in supramolecular solar cells

  12. Thermosensitive Polymer Nanocontainers Prepared by Self-Assembly of Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    Chen Xiangrong; Ding Xiaobing; Zheng Zhaohui; Peng Yuxing

    2004-01-01

    In recent years, considerable effort has been devoted to the preparation of polymer nanocontainers because of their unique advantages. Compared to polymer microspheres or micelles,polymer nanocontainers are hollow-sphere structures and can encapsulate large quantities of guest molecules or large-sized guests within the "empty" core domain. Compared to polymer vesicles,polymer nanocontainers have enough mechanical stability to prevent them from structure changes due to covalent or ionic interactions responsible for their formation. Therefore, polymer nanocontainers have many potential applications such as confined reaction vesicles, drug carriers,protective shells for cells or enzymes, artificial cells and so on. However, most of polymer nanocontainers reported by now, load and release guest molecules from their interior only through diffuse mechanism. It is rather difficult to control intelligently the process based on demands. In order to solve this problem, one promising strategy is to design intelligent polymer nanocontainers.They can undergo reversible structural transitions from a closed to an open state with the help of external stimuli.In this paper, we report on our preliminary study of the thermosensitive polymer nanocontainers formed by self-assembly of the block copolymers PCEMA-b-PNIPAM and sequent photo-crosslinking of PCEMA shells.Block copolymers PCEMA-b-PNIPAM were prepared by reacting PHEMA-b-PNIPAM with excess cinnamoyl chloride in pyridine at room temperature, where PHEMA-b-PNIPAM was prepared by reacting succinimidyl ester of PHEMA-COOH with PNIPAAm-NH2, similar to the method of the literature. The block copolymers were characterized by FTIR and 1H-NMR and GPC.To obtain polymer vesicles, deionized water, as a precipitant, was added at a rate of 0.3wt%/10s with vigorous stirring to the PCEMA-b-PNIPAM solution in THE After the formation of polymer vesicles, more water was added until the water content reached ca.50wt%. The hollow structure of the

  13. Influence of coupling agent's self-assembly upon performance of polymer coated FBG pressure sensors

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; QIAO Xue-guang; SHAO-Jun; WANG Hong-liang; FENG De-quan

    2006-01-01

    @@ Based on super-molecule self-assembly and entropy-driven self-assembly mechanisms,the coupling agent was evolved into colloid spheres with average diameter of 2-2.3 μm on the fiber Bragg grating (FBG) with silicon substrate,and the coupling mechanism among polymer,coupling agent and FBG was analyzed.The polymer coated FBG pressure sensors was capsulated by uniform coupling mode and self-assembly coupling mode of the coupling agent respectively,and their performance parameters were tested.It was shown,adopting the self-assembly coating of coupling agent and with the same other capsulated technologies,that the measuring range of the sensor expanded from 0.6 MPa to 1.6 MPa,the repeated times for coupling failure increased from 54 to 125 times and the pressure sensitivity coefficient enhanced from 1.09 to 2.98.By controlling the diameter of the spheres and the line density,the measuring range and the sensitivity of the FBG pressure sensors can be obviously improved.

  14. In-process assembly of micro metal inserts in a polymer matrix

    DEFF Research Database (Denmark)

    Tosello, Guido; Hansen, Hans Nørgaard

    2006-01-01

    New functionalities and smaller dimensions of micro products can be achieved by means of a higher degree of integration of both materials and components. Smart micro assembly techniques (such as on-the-machine assembly) together with hybrid structures (as metal inserts in polymer matrix......) are suitable solutions to manufacture new micro products with several integrated functionalities, reduced number of components and assembly phases, as well as the possibility to be replicated in a high number of specimens. Innovative manufacturing systems, as well as new design rules and testing methodologies...... embossing-like process which allows fast developing time and the possibility of batch process. Different levels of surface roughness and metal insert thickness were applied in a systematic design of experiments. The results show a strong influence of surface texture on bonding strength. The testing...

  15. Nanowire mesh solar fuels generator

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Peidong; Chan, Candace; Sun, Jianwei; Liu, Bin

    2016-05-24

    This disclosure provides systems, methods, and apparatus related to a nanowire mesh solar fuels generator. In one aspect, a nanowire mesh solar fuels generator includes (1) a photoanode configured to perform water oxidation and (2) a photocathode configured to perform water reduction. The photocathode is in electrical contact with the photoanode. The photoanode may include a high surface area network of photoanode nanowires. The photocathode may include a high surface area network of photocathode nanowires. In some embodiments, the nanowire mesh solar fuels generator may include an ion conductive polymer infiltrating the photoanode and the photocathode in the region where the photocathode is in electrical contact with the photoanode.

  16. The influence of self-assembly behavior of nanoparticles on the dielectric polymer composites

    Directory of Open Access Journals (Sweden)

    Xin Lu

    2013-11-01

    Full Text Available To clearify the influence of the distribution of the conductive nanoparticles on the dielectric properties of the corresponding polymer composites, the microstructure and dielectric character of the composites based on the oleic acid modified ferroferric oxide and polyvinylidene fluoride (PVDF polymer have been studied experimentally. It is found that these composites exhibit a normal percolative phase transition over the filler content from insulator to conductor, consistent with the classical percolation theory. However, when the percentage of fillers is at a certain value which is below the percolation threshold, these nanoparticles can assemble into a special porous structure in the PVDF matrix, associated with the enhancement of dielectric constant at low frequency. In addition, the controllable dispersion of conducting nanoparticles in a polymer matrix can prevent premature agglomeration at low filling fractions and avoid the appearance of anomalously early percolation. Therefore, the self-assembly behavior of nanoparticles can be beneficial to preparation of the high dielectric constant and low loss composites for the application of electric energy storage.

  17. Solvent-dependent self-assembly and ordering in slow-drying semi-crystalline conjugated polymer solutions

    KAUST Repository

    Zhao, Kui

    2015-09-07

    The mechanistic understanding of the intrinsic molecular self-assembly of conjugated polymers is of immense importance to controlling the microstructure development in organic semiconducting thin films, with meaningful impact on charge transport and optoelectronic properties. Yet, to date the vast majority of studies have focused on the fast solution process itself, with studies of slower intrinsic molecular self-assembly in formulations lagging behind. Here we have investigated molecular self-assembly during spontaneous organization and uncovered how changes in formulation influence the microstructure, morphology and transport properties of conjugated polymer thin films. Our results suggest that the polymer-solvent interaction is the key factor for the molecular self-assembly and changes in macroscopic charge transport, which is in contrast with most solution processes, such as spin-coating and blade coating, where solvent drying kinetics dominates the aggregation and crystallization processes. Energetically favourable interactions between the polymer and its solvent are shown to cause chain expansion, resulting in a large hydrodynamic volume and few chain entanglements in solution. This provides molecular freedom for self-assembly and is shown to greatly enhance the local and long range order of the polymer, intra-chain backbone planarity and crystallite size. These improvements, in turn, are shown to endow the conjugated polymer with high carrier transport, as demonstrated by organic thin film transistors.

  18. Mono- and Bis-Terpyridine-Based Dimer and Metallo-Organic Polymers as Ionic Templates for Preparation of Multi-Metallic Au Nanocluster and Nanowires.

    Science.gov (United States)

    Liu, Die; Cao, Hongda; Jiang, Zhilong; Wu, Tun; Sun, Xiaoyi; Wang, Pingshan; Moorefield, Charles N; Dai, Liming; Newkome, George R

    2016-03-01

    The preparation of multi-metallic Au nanocluster and nanowires has been achieved using terpyridine-based metallo-organic polymers as multi-ionic templates through a straightforward counterion exchange with aqueous NaAuCl4 followed by a mild reduction in-situ with sodium citrate. The mild reduction of the [TpyFeTpy]2+ x 2[AuCl4]- complex, derived from [TpyFeTpy]2+ x 2Cl- 1 (tpy = 2,2':6',2"-terpyridine), led to the formation of Au nanoclusters (Au NC) with diameters ranging from 7.5-88 nm. Each Au NC alone contained multiple nanoparticles, with diameters ranging from 2.5-4.5 nm. 1,4-bis-terpyridine based metallo-oraganic polymer [-TpyFeTpy-TpyFeTpy-]n(2n+) x [Cl]2n- 2 was found to generate a multi-ionic metallo-polymer with AuCl4- as the counterion, after mild reduction with sodium citrate, resulting in irregular zigzag shaped Au nanowires (Au NW). The prepared Au NW from the di-metallic complex 3 should find applications within electronic devices. Both Au NC and NW were also found to possess excellent catalytic properties. PMID:27455678

  19. Electronic transport properties of self-assembled thin films of inorganic nanoparticles and polymers

    Energy Technology Data Exchange (ETDEWEB)

    Kniprath, Rolf; Kirstein, Stefan [Institut fuer Physik, Humboldt Universitaet zu Berlin (Germany)

    2007-07-01

    We report on the electronic transport properties and the photovoltaic effect observed in composite thin films of nanoporous TiO{sub 2} and holeconducting polymers. These organic-inorganic heterojunction structures represent a hybrid of all-organic and inorganic dye-sensitized solar cell concepts. The nanoporous films of TiO{sub 2} were grown on transparent conducting oxide substrates with a layer-by-layer self-assembly process using TiO{sub 2} nanoparticles and served as electron conductors. By drop-casting polymer solutions on top we fabricated two types of heterojunction devices: For the first type, we applied a water-soluble thiophene polymer that acted as both a light absorber and a hole transport layer (HTL). For the second type we sensitized TiO{sub 2} with strongly light absorbing CdTe nanoparticles and used the transparent polymer TFB as a HTL. I-V-measurements through Au back contacts under white light and in the dark yielded a diode characteristic with photovoltages of up to 0.8 V for both setups and photocurrent densities on the order of 1 {mu}A/cm{sup 2}.

  20. Effect of Charge Patterning on the Phase Behavior of Polymer Coacervates for Charge Driven Self Assembly

    Science.gov (United States)

    Radhakrishna, Mithun; Sing, Charles E.

    Oppositely charged polymers can undergo associative liquid-liquid phase separation when mixed under suitable conditions of ionic strength, temperature and pH to form what are known as `polymeric complex coacervates'. Polymer coacervates find use in diverse array of applications like microencapsulation, drug delivery, membrane filtration and underwater adhesives. The similarity between complex coacervate environments and those in biological systems has also found relevance in areas of bio-mimicry. Our previous works have demonstrated how local charge correlations and molecular connectivity can drastically affect the phase behavior of coacervates. The precise location of charges along the chain therefore dramatically influences the local charge correlations, which consequently influences the phase behavior of coacervates. We investigate the effect of charge patterning along the polymer chain on the phase behavior of coacervates in the framework of the Restricted Primitive Model using Gibbs Ensemble Monte Carlo simulations. Our results show that charge patterning dramatically changes the phase behavior of polymer coacervates, which contrasts with the predictions of the classical Voorn-Overbeek theory. This provides the basis for designing new materials through charge driven self assembly by controlling the positioning of the charged monomers along the chain.

  1. Fracton pairing mechanism for unconventional superconductors: Self-assembling organic polymers and copper-oxide compounds

    DEFF Research Database (Denmark)

    Milovanov, A.V.; Juul Rasmussen, J.

    2002-01-01

    Self-assembling organic polymers and copper-oxide compounds are two classes of unconventional superconductors, whose challenging behavior does not comply with the traditional picture of Bardeen-Cooper-Schrieffer (BCS) superconductivity in regular crystals. In this paper, we propose a theoretical...... or holes) exchange fracton excitations, quantum oscillations of fractal lattices that mimic the complex microscopic organization of the unconventional superconductors. For the copper oxides, the superconducting transition temperature T-c as predicted by the fracton mechanism is of the order of similar to......-induced superconducting phase in the electron-doped polymers, we simultaneously find a rather modest transition temperature of similar to2-3 K owing to the limitations imposed by the electron tunneling processes on a fractal geometry. We speculate that the hole-type superconductivity shows a larger onset temperature when...

  2. Self-assembly of azobenzene based side-chain liquid crystalline polymer and -alkyloxybenzoic acids

    Indian Academy of Sciences (India)

    Kumarasamy Gayathri; Subramanian Balamurugan; Palaninathan Kannan

    2011-05-01

    Liquid crystalline pendant polymeric complexes have been obtained by supramolecular assembly of two mesogenic components namely, poly[4-(10-acryloyloxydecyloxy)-4'- phenylazobenzonitrile] (P10) and 4-alkyloxybenzoic acids (A7-A12). Hydrogen bond formed between carboxylic acid and cyano moiety served as molecular bridge. The polymeric complexes acquitted as undivided liquid crystalline properties exhibited stable and enantiotropic mesophases. The precursor, monomer and polymer were analysed by 1H-NMR and 13C-NMR spectroscopy. The hydrogen bonding interaction in polymer complexes (P10-A7 to P10-A12) was investigated by FT-IR spectroscopy. The thermal behaviours and textural analysis were studied by differential scanning calorimetry and polarized optical microscopy respectively.

  3. Electrostatically self-assembled nonconjugated polyelectrolytes as an ideal interfacial layer for inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hongkyu; Hong, Soonil; Lee, Jongjin; Lee, Kwanghee [School of Materials Science and Engineering, Heeger Center for Advanced Materials, Research Institute for Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2012-06-12

    Nonconjugated polyelectrolytes (NPEs) are ideal interfacial layers for high-efficiency inverted polymer solar cells (I-PSCs). The NPEs are coated on indium tin oxide (ITO) using ionic self-assembly. Due to dipole formation between the cationic amine of the NPE and the anionic oxygen of ITO, the work function of ITO is dramatically reduced from 4.8 to 4.0 eV. Using the modified ITO, UV-independent I-PSCs with high efficiencies of 6.3% are demonstrated. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Self-assembly of DNA-polymer complexes using template polymerization.

    Science.gov (United States)

    Trubetskoy, V S; Budker, V G; Hanson, L J; Slattum, P M; Wolff, J A; Hagstrom, J E

    1998-09-15

    The self-assembly of supramolecular complexes of nucleic acids and polymers is of relevance to several biological processes including viral and chromatin formation as well as gene therapy vector design. We now show that template polymerization facilitates condensation of DNA into particles that are <150 nm in diameter. Inclusion of a poly(ethylene glycol)-containing monomer prevents aggregation of these particles. The DNA within the particles remains biologically active and can express foreign genes in cells. The formation or breakage of covalent bonds has until now not been employed to compact DNA into artificial particles.

  5. Investigation of composites of polymers and Mo{sub 6}S{sub 2}I{sub 8} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Hyun; Jo, HyeRan; Seong, Chae-Yong [Graduate School of Convergence Science and Technology, Seoul National University, Suwon (Korea, Republic of); Kim, Kyung Ho; Park, Yung Woo [Department of Physics and Astronomy, Seoul National University (Korea, Republic of); Mrzel, Ales [Jozef Stefan Institute, Ljubljana (Slovenia); Scalia, Giusy [Graduate School of Convergence Science and Technology, Seoul National University, Suwon (Korea, Republic of); Advanced Institutes of Convergence Technology (AICT), Seoul National University, Suwon (Korea, Republic of)

    2014-05-15

    We have dispersed Mo{sub 6}S{sub 2}I{sub 8} nanowires in different types of polyvinyl alcohol (PVA), polystyrene sulfonate (PSS) and surfactants, analyzing their effect on the quality of the dispersion. Raman spectroscopy was employed to investigates the nanowires from suspensions as well as in films. I-V characteristics of networks of nanowires, deposited from suspensions stabilized by PSS, were measured as function of temperature, observing, in the linear region, a variable-range hopping behavior typical of disordered systems. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Performance of dielectric nanocomposites: matrix-free, hairy nanoparticle assemblies and amorphous polymer-nanoparticle blends.

    Science.gov (United States)

    Grabowski, Christopher A; Koerner, Hilmar; Meth, Jeffrey S; Dang, Alei; Hui, Chin Ming; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Durstock, Michael F; Vaia, Richard A

    2014-12-10

    Demands to increase the stored energy density of electrostatic capacitors have spurred the development of materials with enhanced dielectric breakdown, improved permittivity, and reduced dielectric loss. Polymer nanocomposites (PNCs), consisting of a blend of amorphous polymer and dielectric nanofillers, have been studied intensely to satisfy these goals; however, nanoparticle aggregates, field localization due to dielectric mismatch between particle and matrix, and the poorly understood role of interface compatibilization have challenged progress. To expand the understanding of the inter-relation between these factors and, thus, enable rational optimization of low and high contrast PNC dielectrics, we compare the dielectric performance of matrix-free hairy nanoparticle assemblies (aHNPs) to blended PNCs in the regime of low dielectric contrast to establish how morphology and interface impact energy storage and breakdown across different polymer matrices (polystyrene, PS, and poly(methyl methacrylate), PMMA) and nanoparticle loadings (0-50% (v/v) silica). The findings indicate that the route (aHNP versus blending) to well-dispersed morphology has, at most, a minor impact on breakdown strength trends with nanoparticle volume fraction; the only exception being at intermediate loadings of silica in PMMA (15% (v/v)). Conversely, aHNPs show substantial improvements in reducing dielectric loss and maintaining charge/discharge efficiency. For example, low-frequency dielectric loss (1 Hz-1 kHz) of PS and PMMA aHNP films was essentially unchanged up to a silica content of 50% (v/v), whereas traditional blends showed a monotonically increasing loss with silica loading. Similar benefits are seen via high-field polarization loop measurements where energy storage for ∼15% (v/v) silica loaded PMMA and PS aHNPs were 50% and 200% greater than respective comparable PNC blends. Overall, these findings on low dielectric contrast PNCs clearly point to the performance benefits of

  7. Phospholipid-polymer amphiphile hybrid assemblies and their interaction with macrophages.

    Science.gov (United States)

    Panneerselvam, Karthiga; Lynge, Martin E; Riber, Camilla Frich; Mena-Hernando, Sofia; Smith, Anton A A; Goldie, Kenneth N; Zelikin, Alexander N; Städler, Brigitte

    2015-09-01

    Recently, the combination of lipids and block copolymers has become an alternative to liposomes and polymersomes as nano-sized drug carriers. We synthesize novel block copolymers consisting of poly(cholesteryl acrylate) as the hydrophobic core and poly(N-isopropylacrylamide) (PNIPAAm) as the hydrophilic extensions. Their successful phospholipid-assisted assembly into vesicles is demonstrated using the evaporation-hydration method. The preserved thermo-responsive property of the lipid-polymer hybrids is shown by a temperature dependent adsorption behaviour of the vesicles to poly(l lysine) coated surfaces. As expected, the vesicle adsorption is found to be higher at elevated temperatures. The cellular uptake efficiency of hybrids is assessed using macrophages with applied shear stress. The amount of adhering macrophages is affected by the time and level of applied shear stress. Further, it is found that shorter PNIPAAm extensions lead to higher uptake of the assemblies by the macrophages with applied shear stress. No inherent cytotoxicity is observed at the tested conditions. Taken together, this first example of responsive lipid-polymer hybrids, and their positive biological evaluation makes them promising nano-sized drug carrier candidates. PMID:26339330

  8. Polymer GARD: computer simulation of covalent bond formation in reproducing molecular assemblies.

    Science.gov (United States)

    Shenhav, Barak; Bar-Even, Arren; Kafri, Ran; Lancet, Doron

    2005-04-01

    The basic Graded Autocatalysis Replication Domain (GARD) model consists of a repertoire of small molecules, typically amphiphiles, which join and leave a non-covalent micelle-like assembly. Its replication behavior is due to occasional fission, followed by a homeostatic growth process governed by the assembly's composition. Limitations of the basic GARD model are its small finite molecular repertoire and the lack of a clear path from a 'monomer world' towards polymer-based living entities. We have now devised an extension of the model (polymer GARD or P-GARD), where a monomer-based GARD serves as a 'scaffold' for oligomer formation, as a result of internal chemical rules. We tested this concept with computer simulations of a simple case of monovalent monomers, whereby more complex molecules (dimers) are formed internally, in a manner resembling biosynthetic metabolism. We have observed events of dimer 'take-over' - the formation of compositionally stable, replication-prone quasi stationary states (composomes) that have appreciable dimer content. The appearance of novel metabolism-like networks obeys a time-dependent power law, reminiscent of evolution under punctuated equilibrium. A simulation under constant population conditions shows the dynamics of takeover and extinction of different composomes, leading to the generation of different population distributions. The P-GARD model offers a scenario whereby biopolymer formation may be a result of rather than a prerequisite for early life-like processes. PMID:16010993

  9. Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation.

    Science.gov (United States)

    Deng, Chao; Zhang, Qiu Gen; Han, Guang Lu; Gong, Yi; Zhu, Ai Mei; Liu, Qing Lin

    2013-11-21

    Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m(-2) h(-1) bar(-1)) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles. PMID:24072040

  10. RAFT Synthesis and Self-Assembly of Free-Base Porphyrin Cored Star Polymers

    Directory of Open Access Journals (Sweden)

    Lin Wu

    2011-01-01

    Full Text Available Reversible addition fragmentation chain transfer (RAFT synthesis and self-assembly of free-base porphyrin cored star polymers are reported. The polymerization, in the presence of a free-base porphyrin cored chain transfer agent (CTA-FBP, produced porphyrin star polymers with controlled molecular weights and narrow polydispersities for a number of monomers including N, N-dimethylacrylamide (DMA and styrene (St. Well-defined amphiphilic star block copolymers, P-(PS-PDMA4 and P-(PDMA-PS4 (P: porphyrin, were also prepared and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers as characterized by TEM. UV-vis studies suggested star-like micelles were formed from P-(PS-PDMA4, while P-(PDMA-PS4 aggregated into flower-like micelles. Spectrophotometric titrations indicated that the optical response of these two micelles to external ions was a function of micellar structures. These structure-related properties will be used for micelle studies and functional material development in the future.

  11. Polymer-virus core-shell structures prepared via co-assembly and template synthesis methods

    Institute of Scientific and Technical Information of China (English)

    SUTHIWANGCHAROEN; Nisaraporn; PREVELIGE; Peter; E.Jr

    2010-01-01

    Bionanoparticles(BNPs),consisting of virus and virus-like assemblies,have attracted much attention in the biomedical field for their applications such as imaging and targeted drug delivery,owing to their well-defined structures and well-controlled chemistries.BNPs-based core-shell structures provide a unique system for the investigation of biological interactions such as protein-protein and protein-carbohydrate interactions.However,it is still a challenge to prepare the BNPs-based core-shell structures.Herein,we describe(i) co-assembly method and(ii) template synthesis method in the development of polymer-BNPs core-shell structures.These two methods can be divided into three different systems.In system A,different polymers including poly(2-vinylpyridine)(P2VP),poly(4-vinylpyridine)(P4VP) and poly(ε-caprolactone)-block-poly(2-vinylpyridine)(PCL-b-P2VP) can form a raspberry-like structure with BNPs.In system B,polystyrene(PS) spheres end capped with free amine and BNPs can form a core-shell structure.In System C,layer-by-layer(LBL) method is used to prepare positive charged PS particles,which can be used as a template to form the core-shell structures with BNPs.These two methods may open a new way for preparing novel protein-based functional materials for potential applications in the biomedical field.

  12. Largely enhanced efficiency in ZnO nanowire/p-polymer hybridized inorganic/organic ultraviolet light-emitting diode by piezo-phototronic effect.

    Science.gov (United States)

    Yang, Qing; Liu, Ying; Pan, Caofeng; Chen, Jun; Wen, Xiaonan; Wang, Zhong Lin

    2013-02-13

    ZnO nanowire inorganic/organic hybrid ultraviolet (UV) light-emitting diodes (LEDs) have attracted considerable attention as they not only combine the high flexibility of polymers with the structural and chemical stability of inorganic nanostructures but also have a higher light extraction efficiency than thin film structures. However, up to date, the external quantum efficiency of UV LED based on ZnO nanostructures has been limited by a lack of efficient methods to achieve a balance between electron contributed current and hole contributed current that reduces the nonradiative recombination at interface. Here we demonstrate that the piezo-phototronic effect can largely enhance the efficiency of a hybridized inorganic/organic LED made of a ZnO nanowire/p-polymer structure, by trimming the electron current to match the hole current and increasing the localized hole density near the interface through a carrier channel created by piezoelectric polarization charges on the ZnO side. The external efficiency of the hybrid LED was enhanced by at least a factor of 2 after applying a proper strain, reaching 5.92%. This study offers a new concept for increasing organic LED efficiency and has a great potential for a wide variety of high-performance flexible optoelectronic devices.

  13. Kinetically controlled nanostructure formation in self-assembled globular protein-polymer diblock copolymers.

    Science.gov (United States)

    Thomas, Carla S; Xu, Liza; Olsen, Bradley D

    2012-09-10

    Aqueous processing of globular protein-polymer diblock copolymers into solid-state materials and subsequent solvent annealing enables kinetic and thermodynamic control of nanostructure formation to produce block copolymer morphologies that maintain a high degree of protein fold and function. When model diblock copolymers composed of mCherry-b-poly(N-isopropylacrylamide) are used, orthogonal control over solubility of the protein block through changes in pH and the polymer block through changes in temperature is demonstrated during casting and solvent annealing. Hexagonal cylinders, perforated lamellae, lamellae, or hexagonal and disordered micellar phases are observed, depending on the coil fraction of the block copolymer and the kinetic pathway used for self-assembly. Good solvents for the polymer block produce ordered structures reminiscent of coil-coil diblock copolymers, while an unfavorable solvent results in kinetically trapped micellar structures. Decreasing solvent quality for the protein improves long-range ordering, suggesting that the strength of protein interactions influences nanostructure formation. Subsequent solvent annealing results in evolution of the nanostructures, with the best ordering and the highest protein function observed when annealing in a good solvent for both blocks. While protein secondary structure was found to be almost entirely preserved for all processing pathways, UV-vis spectroscopy of solid-state films indicates that using a good solvent for the protein block enables up to 70% of the protein to be retained in its functional form. PMID:22924842

  14. Polymer/surfactant assisted self-assembly of nanoparticles into Langmuir–Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Alejo, T.; Merchán, M.D. [Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, Plaza de los Caídos s/n, E-37008 Salamanca (Spain); Velázquez, M.M., E-mail: mvsal@usal.es [Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, Plaza de los Caídos s/n, E-37008 Salamanca (Spain); Pérez-Hernández, J.A. [Centro de Láseres Pulsados Ultraintensos (CLPU), E-37008 Salamanca (Spain)

    2013-02-15

    We studied the ability of poly(octadecene-co-maleic anhydride) (PMAO) and a Gemini surfactant [C{sub 18}H{sub 37} (CH{sub 3}){sub 2}N{sup +}Br{sup −}–(CH{sub 2}){sub 2}–N{sup +}Br{sup −}(CH{sub 3}){sub 2} C{sub 18}H{sub 37}] (18-2-18) to assist in the self-assembly process of CdSe quantum dots (QDs) at the air–water interface. Results show that, while QD agglomeration is generally inhibited by the addition of these components to the Langmuir monolayer of QDs, structure of the film transferred onto mica by the Langmuir–Blodgett method is strongly affected by the dewetting process. Nucleation-and-growth of holes and spinodal-like dewetting were respectively observed in the presence of either PMAO or 18-2-18. When PMAO/18-2-18 mixtures were used, both mechanisms were allowed; nevertheless, even in films prepared with mixtures of low polymer contents, characteristic morphology from the polymer dewetting route prevailed. Highlights: ► Effect of the composition on the LB films of QDs/polymer. ► Effect of the composition on the LB films of QDs/Gemini surfactant. ► Dewetting mechanisms.

  15. Enhancing the Thermal Conductance of Polymer and Sapphire Interface via Self-Assembled Monolayer.

    Science.gov (United States)

    Zheng, Kun; Sun, Fangyuan; Zhu, Jie; Ma, Yongmei; Li, Xiaobo; Tang, Dawei; Wang, Fosong; Wang, Xiaojia

    2016-08-23

    Interfacial thermal conductance (ITC) receives enormous consideration because of its significance in determining thermal performance of hybrid materials, such as polymer based nanocomposites. In this study, the ITC between sapphire and polystyrene (PS) was systematically investigated by time domain thermoreflectance (TDTR) method. Silane based self-assembled monolayers (SAMs) with varying end groups, -NH2, -Cl, -SH and -H, were introduced into sapphire/PS interface, and their effects on ITC were investigated. The ITC was found to be enhanced up by a factor of 7 through functionalizing the sapphire surface with SAM, which ends with a chloride group (-Cl). The results show that the enhancement of the thermal transport across the SAM-functionalized interface comes from both strong covalent bonding between sapphire and silane-based SAM, and the high compatibility between the SAM and PS. Among the SAMs studied in this work, we found that the ITC almost linearly depends on solubility parameters, which could be the dominant factor influencing on the ITC compared with wettability and adhesion. The SAMs serve as an intermediate layer that bridges the sapphire and PS. Such a feature can be applied to ceramic-polymer immiscible interfaces by functionalizing the ceramic surface with molecules that are miscible with the polymer materials. This research provides guidance on the design of critical-heat transfer materials such as composites and nanofluids for thermal management. PMID:27501117

  16. Invertible micellar polymer assemblies for delivery of poorly water-soluble drugs.

    Science.gov (United States)

    Hevus, Ivan; Modgil, Amit; Daniels, Justin; Kohut, Ananiy; Sun, Chengwen; Stafslien, Shane; Voronov, Andriy

    2012-08-13

    Strategically designed amphiphilic invertible polymers (AIPs) are capable of (i) self-assembling into invertible micellar assemblies (IMAs) in response to changes in polarity of environment, polymer concentration, and structure, (ii) accommodating (solubilizing) substances that are otherwise insoluble in water, and (iii) inverting their molecular conformation in response to changes in the polarity of the local environment. The unique ability of AIPs to invert the molecular conformation depending on the polarity of the environment can be a decisive factor in establishing the novel stimuli-responsive mechanism of solubilized drug release that is induced just in response to a change in the polarity of the environment. The IMA capability to solubilize lipophilic drugs and deliver and release the cargo molecules by conformational inversion of polymer macromolecules in response to a change of the polarity of the environment was demonstrated by loading IMA with a phytochemical drug, curcumin. It was demonstrated that four sets of micellar vehicles based on different AIPs were capable of delivering the curcumin from water to an organic medium (1-octanol) by means of unique mechanism: AIP conformational inversion in response to changing polarity from polar to nonpolar. The IMAs are shown to be nontoxic against human cells up to a concentration of 10 mg/L. On the other hand, the curcumin-loaded IMAs are cytotoxic to breast carcinoma cells at this concentration, which confirms the potential of IMA-based vehicles in controlled delivery of poorly water-soluble drug candidates and release by means of this novel stimuli-responsive mechanism.

  17. Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites.

    Science.gov (United States)

    Kirmayer, Saar; Aharon, Eyal; Dovgolevsky, Ekaterina; Kalina, Michael; Frey, Gitti L

    2007-06-15

    Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

  18. Solution-processed low dimensional nanomaterials with self-assembled polymers for flexible photo-electronic devices (Presentation Recording)

    Science.gov (United States)

    Park, Cheolmin

    2015-09-01

    Self assembly driven by complicated but systematic hierarchical interactions offers a qualified alternative for fabricating functional micron or nanometer scale pattern structures that have been potentially useful for various organic and nanotechnological devices. Self assembled nanostructures generated from synthetic polymer systems such as controlled polymer blends, semi-crystalline polymers and block copolymers have gained a great attention not only because of the variety of nanostructures they can evolve but also because of the controllability of these structures by external stimuli. In this presentation, various novel photo-electronic materials and devices are introduced based on the solution-processed low dimensional nanomaterials such as networked carbon nanotubes (CNTs), reduced graphene oxides (rGOs) and 2 dimensional transition metal dichalcogenides (TMDs) with self assembled polymers including field effect transistor, electroluminescent device, non-volatile memory and photodetector. For instance, a nanocomposite of networked CNTs and a fluorescent polymer turned out an efficient field induced electroluminescent layer under alternating current (AC) as a potential candidate for next generation displays and lightings. Furthermore, scalable and simple strategies employed for fabricating rGO as well as TMD nanohybrid films allowed for high performance and mechanically flexible non-volatile resistive polymer memory devices and broad band photo-detectors, respectively.

  19. Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers.

    Science.gov (United States)

    Zhu, Baolei; Merindol, Remi; Benitez, Alejandro J; Wang, Baochun; Walther, Andreas

    2016-05-01

    Natural composites are hierarchically structured by combination of ordered colloidal and molecular length scales. They inspire future, biomimetic, and lightweight nanocomposites, in which extraordinary mechanical properties are in reach by understanding and mastering hierarchical structure formation as tools to engineer multiscale deformation mechanisms. Here we describe a hierarchically self-assembled, cholesteric nanocomposite with well-defined colloid-based helical structure and supramolecular hydrogen bonds engineered on the molecular level in the polymer matrix. We use reversible addition-fragmentation transfer polymerization to synthesize well-defined hydrophilic, nonionic polymers with a varying functionalization density of 4-fold hydrogen-bonding ureidopyrimidinone (UPy) motifs. We show that these copolymers can be coassembled with cellulose nanocrystals (CNC), a sustainable, stiff, rod-like reinforcement, to give ordered cholesteric phases with characteristic photonic stop bands. The dimensions of the helical pitch are controlled by the ratio of polymer/CNC, confirming a smooth integration into the colloidal structure. With respect to the effect of the supramolecular motifs, we demonstrate that those regulate the swelling when exposing the biomimetic hybrids to water, and they allow engineering the photonic response. Moreover, the amount of hydrogen bonds and the polymer fraction are decisive in defining the mechanical properties. An Ashby plot comparing previous ordered CNC-based nanocomposites with our new hierarchical ones reveals that molecular engineering allows us to span an unprecedented mechanical property range from highest inelastic deformation (strain up to ∼13%) to highest stiffness (E ∼ 15 GPa) and combinations of both. We envisage that further rational design of the molecular interactions will provide efficient tools for enhancing the multifunctional property profiles of such bioinspired nanocomposites. PMID:27067311

  20. Polymer Crosslinked 3-D Assemblies of Nanoparticles: Mechanically Strong Lightweight Porous Materials

    Science.gov (United States)

    Leventis, Nicholas

    2005-01-01

    In analogy to supramolecular assemblies, which are pursued because of properties above and beyond those of the individual molecules, self-standing monolithic three-dimensional assemblies of nanoparticles also have unique properties attributed to their structure. For example, ultra low-density 3-D assemblies of silica nanoparticles, known as silica aerogels, are characterized by large internal void space, high surface area and very low thermal conductivity. Aerogels, however, are also extremely fragile materials, limiting their application to a few specialized environments, e.g., in nuclear reactors as Cerenkov radiation detectors, in space (refer to NASA's Stardust Program) and aboard certain planetary vehicles (thermal insulators on Mars Rovers in 1997 and 2004). The fragility problem is traced to well-defined weak points in the aerogel skeletal framework, the interparticle necks. Using the surface functionality of the nanoparticle building blocks as a focal point, we have directed attachment of a conformal polymer coating over the entire framework, rendering all necks wider. Thus, although the bulk density may increase only by 3x, the mesoporosity (pores in the range 2-50 nm) remains unchanged, while the strength of the material increases by up to 300... Having addressed the fragility problem, aerogels are now robust materials, and a variety of applications, ranging from thermal/acoustic insulators to catalyst supports, to platform for sensors, and dielectrics are all within reach. Our approach employs molecular science to manipulate nanoscopic matter for achieving useful macroscopic properties, and in our view it resides at the core of what defines nanotechnology. In that spirit, this technology is expandable in three directions. Thus, we have already crosslinked successfully amine-modified silica, and we anticipate that more rich chemistry will be realized by been creative with the nanoparticle surface modifiers. On the other hand, although we do not expect

  1. A novel electrochemical aptasensor for highly sensitive detection of thrombin based on the autonomous assembly of hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme nanowires

    International Nuclear Information System (INIS)

    Highlights: • This assay is label-free, the signal can be read out by measuring the electrochemical signal of hemin. • The hemin/G-quadruplex HRP-DNAzyme nanowires were formed via EXPAR reaction and HCR. • The prepared aptasensor exhibited low detection limit and wide linear range to TB. - Abstract: In this work, a new signal amplified strategy was constructed based on isothermal exponential amplification reaction (EXPAR) and hybridization chain reaction (HCR) generating the hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme (HRP-mimicking DNAzyme) nanowires as signal output component for the sensitive detection of thrombin (TB). We employed EXPAR’s ultra-high amplification efficiency to produce a large amount of two hairpin helper DNAs within a minutes. And then the resultant two hairpin helper DNAs could autonomously assemble the hemin/G-quadruplex HRP-mimicking DNAzymes nanowires as the redox-active reporter units on the electrode surface via hybridization chain reaction (HCR). The hemin/G-quadruplex structures simultaneously served as electron transfer medium and electrocatalyst to amplify the signal in the presence of H2O2. Specifically, only when the EXPAR reaction process has occurred, the HCR could be achieved and the hemin/G-quadruplex complexes could be formed on the surface of an electrode to give a detectable signal. The proposed strategy combines the amplification power of the EXPAR, HCR, and the inherent high sensitivity of the electrochemical detection. With such design, the proposed assay showed a good linear relationship within the range of 0.1 pM–50 nM with a detection limit of 33 fM (defined as S/N = 3) for TB

  2. A novel electrochemical aptasensor for highly sensitive detection of thrombin based on the autonomous assembly of hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Shunbi, E-mail: xieshunbi@163.com; Chai, Yaqin, E-mail: yaqinchai@swu.edu.cn; Yuan, Yali; Bai, Lijuan; Yuan, Ruo, E-mail: yuanruo@swu.edu.cn

    2014-06-01

    Highlights: • This assay is label-free, the signal can be read out by measuring the electrochemical signal of hemin. • The hemin/G-quadruplex HRP-DNAzyme nanowires were formed via EXPAR reaction and HCR. • The prepared aptasensor exhibited low detection limit and wide linear range to TB. - Abstract: In this work, a new signal amplified strategy was constructed based on isothermal exponential amplification reaction (EXPAR) and hybridization chain reaction (HCR) generating the hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme (HRP-mimicking DNAzyme) nanowires as signal output component for the sensitive detection of thrombin (TB). We employed EXPAR’s ultra-high amplification efficiency to produce a large amount of two hairpin helper DNAs within a minutes. And then the resultant two hairpin helper DNAs could autonomously assemble the hemin/G-quadruplex HRP-mimicking DNAzymes nanowires as the redox-active reporter units on the electrode surface via hybridization chain reaction (HCR). The hemin/G-quadruplex structures simultaneously served as electron transfer medium and electrocatalyst to amplify the signal in the presence of H{sub 2}O{sub 2}. Specifically, only when the EXPAR reaction process has occurred, the HCR could be achieved and the hemin/G-quadruplex complexes could be formed on the surface of an electrode to give a detectable signal. The proposed strategy combines the amplification power of the EXPAR, HCR, and the inherent high sensitivity of the electrochemical detection. With such design, the proposed assay showed a good linear relationship within the range of 0.1 pM–50 nM with a detection limit of 33 fM (defined as S/N = 3) for TB.

  3. Entanglement of conjugated polymer chains influences molecular self-assembly and carrier transport

    KAUST Repository

    Zhao, Kui

    2013-06-26

    The influence of polymer entanglement on the self-assembly, molecular packing structure, and microstructure of low-Mw (lightly entangled) and high-Mw (highly entangled) poly (3-hexylthiophene) (P3HT), and the carrier transport in thin-film transistors, are investigated. The polymer chains are gradually disentangled in a marginal solvent via ultrasonication of the polymer solution, and demonstrate improved diffusivity of precursor species (coils, aggregates, and microcrystallites), enhanced nucleation and crystallization of P3HT in solution, and self-assembly of well-ordered and highly textured fibrils at the solid-liquid interface. In low-Mw P3HT, reducing chain entanglement enhances interchain and intrachain ordering, but reduces the interconnectivity of ordered domains (tie molecules) due to the presence of short chains, thus deteriorating carrier transport even in the face of improving crystallinity. Reducing chain entanglement in high-Mw P3HT solutions increases carrier mobility up to ≈20-fold, by enhancing interchain and intrachain ordering while maintaining a sufficiently large number of tie molecules between ordered domains. These results indicate that charge carrier mobility is strongly governed by the balancing of intrachain and interchain ordering, on the one hand, and interconnectivity of ordered domains, on the other hand. In high-Mw P3HT, intrachain and interchain ordering appear to be the key bottlenecks to charge transport, whereas in low-Mw P3HT, the limited interconnectivity of the ordered domains acts as the primary bottleneck to charge transport. Conjugated polymer chains of poly(3-hexylthiophene) (P3HT) are gradually disentangled in solution and trends in carrier transport mechanisms in organic thin film transistors for low- and high-molecular weight P3HT are investigated. While intrachain and interchain ordering within ordered domains are the key bottlenecks to charge transport in high-Mw P3HT films, the limited interconnectivity of ordered

  4. Designing Functionalized Nanoparticles for Controlled Assembly in Polymer Matrix: Self consistent PRISM Theory and Monte Carlo simulation Study

    Science.gov (United States)

    Jayaraman, Arthi; Nair, Nitish

    2011-03-01

    Significant interest has grown around the ability to create hybrid materials with controlled spatial arrangement of nanoparticles mediated by a polymer matrix. By functionalizing or grafting polymers on to nanoparticle surfaces and systematically tuning the composition, chemistry, molecular weight and grafting density of the grafted polymers one can tailor the inter-particle interactions and control the assembly/dispersion of the particles in the polymer matrix. In our recent work using self-consistent Polymer Reference Interaction Site Model (PRISM) theory- Monte Carlo simulations we have shown that tailoring the monomer sequences in the grafted copolymers provides a novel route to tuning the effective inter-particle interactions between the functionalized nanoparticles in a polymer matrix. In this talk I will present how monomer sequence and molecular weights (with and without polydispersity) of the grafted polymers, compatibility of the graft and matrix polymers, and nanoparticle size affect the chain conformations of the grafted polymers and the potential of mean force between the grafted nanoparticles in the matrix.

  5. 钼氧化物/聚合物同轴纳米线的制备与表征%Synthesis and Characterization of Mo Oxide/Polymer Coaxial Nanowires

    Institute of Scientific and Technical Information of China (English)

    李硕; 韩春华; 韩久慧; 陈伟

    2011-01-01

    This article introduces the synthesis of coaxial nanowires via in-situ polymerization of organic monomers on the surface of as-synthesized MoO3 nanowires to fabricate MoO3/polymer coaxial nanowires. The as-synthesized nanowires were characterized by X-ray Diffraction, Fourier Transform Infrared Spectroscopy. Field Emission Scanning E-lectron Microscopy and UV-vis spectrum. The results indicate that the polymers are uniformly coated on MoO3 nanowires. And the coaxial nanowires have great potential in photoelectric effect application. This method also provides a possible polymer-coating synthesis route, which can be extended to many other materials.%利用水热法首先合成三氧化钼纳米线,然后通过原位聚合法在三氧化钼纳米线表面分别进行导电聚合物聚吡咯(PPy)、聚噻吩(PTh)和聚乙撑二氧噻吩(PEDOT)的包覆,而得到三氧化钼/聚合物同轴纳米线的方法,并利用X射线衍射、傅里叶变换红外光谱、扫描电子显微镜、紫外可见光谱等手段对其进行了表征和分析,结果表明,聚合物包覆后的同轴纳米线形貌保持良好,并在光电效应应用方面有着较大潜力.这种原位聚合的方法同样可以被应用于其他聚合物包覆结构材料的合成.

  6. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    OpenAIRE

    Hongmei Luo; Qianglu Lin; Stacy Baber; Mahesh Naalla

    2010-01-01

    We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by sca...

  7. Polymer Gard: Computer Simulation of Covalent Bond Formation in Reproducing Molecular Assemblies

    Science.gov (United States)

    Shenhav, Barak; Bar-Even, Arren; Kafri, Ran; Lancet, Doron

    2005-04-01

    The basic Graded Autocatalysis Replication Domain (GARD) model consists of a repertoire of small molecules, typically amphiphiles, which join and leave a non-covalent micelle-like assembly. Its replication behavior is due to occasional fission, followed by a homeostatic growth process governed by the assembly’ s composition. Limitations of the basic GARD model are its small finite molecular repertoire and the lack of a clear path from a ‘monomer world’ towards polymer-based living entities.We have now devised an extension of the model (polymer GARD or P-GARD), where a monomer-based GARD serves as a ‘scaffold’ for oligomer formation, as a result of internal chemical rules. We tested this concept with computer simulations of a simple case of monovalent monomers, whereby more complex molecules (dimers) are formed internally, in a manner resembling biosynthetic metabolism. We have observed events of dimer ‘take-over’ the formation of compositionally stable, replication-prone quasi stationary states (composomes) that have appreciable dimer content. The appearance of novel metabolism-like networks obeys a time-dependent power law, reminiscent of evolution under punctuated equilibrium. A simulation under constant population conditions shows the dynamics of takeover and extinction of different composomes, leading to the generation of different population distributions. The P-GARD model offers a scenario whereby biopolymer formation may be a result of rather than a prerequisite for early life-like processes.

  8. Novel surface treatment materials for aligning block-co-polymer in directed self-assembly processes

    Science.gov (United States)

    Someya, Yasunobu; Wakayama, Hiroyuki; Endo, Takafumi; Sakamoto, Rikimaru

    2014-03-01

    Directed Self-Assembly (DSA) process is one of the attractive processes for creating the very fine pitch pattern. Especially, the contact hole shrink processes with block-co-polymer (BCP) or polymer blend materials were attractive processes for creating very small size hole patterns with better CD uniformity compare to general photo-lithography patterning. In general contact hole shrink process, the pattern of Spin-on Carbon Hardmask (SOC) or the photo Resist pattern created by Negative-Tone Development (NTD) process were selected for guide patterns. Since the alignment property of BCP was affected by the surface of these guide materials, it is important to control the surface condition of guide in order to obtain good shrunk contact hole patterns. In this study, we will report the surface treatment materials to control the surface condition of guide patterns such as SOC or NTD resist to achieve the better contact hole shrink performance. These materials were attached to guide pattern surface and controlled the surface energy.

  9. A TEMPERATURE AND pH DOUBLE SENSITIVE CHOLESTERIC POLYMER FILM FROM A PHOTOPOLYMERIZABLE CHIRAL HYDROGEN-BONDED ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Feng-jin Chen; Jin-bao Guo; Ou-yu Jin; Jie Wei

    2013-01-01

    In this study,a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated.The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal (Ch-LC) monomers mixture containing a photopolymerizable chiral H-bonded assembly (PCHA).The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased,which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film.Additionally,the selective reflection band (SRB) of the cholesteric polymer film in solution with pH > 7showed an obvious red shift with increasing pH values.While the SRB of the cholesteric polymer film in solutions with pH =7 and pH < 7 hardly changed.This pH sensitivity in solutions with pH > 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by-OFF and-K+ ions in the alkaline solution.In contrast,it couldn't happen in the neutral and acidic solutions.The cholesteric polymer film in this study can be used as optical/photonic papers,optical sensors and LCs displays,etc.

  10. Polymer-graphene oxide quadlayer thin-film assemblies with improved gas barrier.

    Science.gov (United States)

    Tzeng, Ping; Stevens, Bart; Devlaming, Ian; Grunlan, Jaime C

    2015-06-01

    Layer-by-layer assembly was used to create quadlayers (QLs) of chitosan (CH), poly(acrylic acid) (PAA), CH, and graphene oxide (GO). Electron microscopy confirmed GO coverage over the film and a highly ordered nanobrick wall structure. By varying pH deviation between CH and PAA, a thick and interdiffused polymer matrix was created because of the altered chain conformation. A 5 CH (pH 5.5)/PAA (pH 3)/CH (pH 5.5)/GO QL assembly (48 nm) exhibits very low oxygen permeability (3.9 × 10(-20) cm(3) cm cm(-2) Pa(-1) s(-1)) that matches SiOx barrier coatings. In an effort to maintain barrier performance under high humidity, GO was thermally reduced to increase hydrophobicity of the film. This reduction step increased H2/CO2 selectivity of a 5 QL film from 5 to 215, exceeding Robeson's upper bound limit. This unique water-based multilayer nanocoating is very promising for a variety of gas purification and packaging applications. PMID:25970136

  11. Interfacial assembly of protein-polymer nano-conjugates into stimulus-responsive biomimetic protocells.

    Science.gov (United States)

    Huang, Xin; Li, Mei; Green, David C; Williams, David S; Patil, Avinash J; Mann, Stephen

    2013-01-01

    The mechanism of spontaneous assembly of microscale compartments is a central question for the origin of life, and has technological repercussions in diverse areas such as materials science, catalysis, biotechnology and biomedicine. Such compartments need to be semi-permeable, structurally robust and capable of housing assemblages of functional components for internalized chemical transformations. In principle, proteins should be ideal building blocks for the construction of membrane-bound compartments but protein vesicles with cell-like properties are extremely rare. Here we present an approach to the interfacial assembly of protein-based micro-compartments (proteinosomes) that are delineated by a semi-permeable, stimulus-responsive, enzymatically active, elastic membrane consisting of a closely packed monolayer of conjugated protein-polymer building blocks. The proteinosomes can be dispersed in oil or water, thermally cycled to temperatures of 70 °C, and partially dried and re-inflated without loss of structural integrity. As a consequence, they exhibit protocellular properties such as guest molecule encapsulation, selective permeability, gene-directed protein synthesis and membrane-gated internalized enzyme catalysis. PMID:23896993

  12. Self-Assembling Nanoparticles of Amphiphilic Polymers for In Vitro and In Vivo FRET Imaging.

    Science.gov (United States)

    Garcia-Amorós, Jaume; Tang, Sicheng; Zhang, Yang; Thapaliya, Ek Raj; Raymo, Françisco M

    2016-01-01

    Self-assembling nanoparticles of amphiphilic polymers are viable delivery vehicles for transporting hydrophobic molecules across hydrophilic media. Noncovalent contacts between the hydrophobic domains of their macromolecular components are responsible for their formation and for providing a nonpolar environment for the encapsulated guests. However, such interactions are reversible and, as a result, these supramolecular hosts can dissociate into their constituents amphiphiles to release the encapsulated cargo. Operating principles to probe the integrity of the nanocarriers and the dynamic exchange of their components are, therefore, essential to monitor the fate of these supramolecular assemblies in biological media. The co-encapsulation of complementary chromophores within their nonpolar interior offers the opportunity to assess their stability on the basis of energy transfer and fluorescence measurements. Indeed, the exchange of excitation energy between the entrapped chromophores can only occur if the nanoparticles retain their integrity to maintain donors and acceptors in close proximity. In fact, energy-transfer schemes are becoming invaluable protocols to elucidate the transport properties of these fascinating supramolecular constructs in a diversity of biological preparations and can facilitate the identification of strategies to deliver contrast agents and/or drugs to target locations in living organisms for potential diagnostic and/or therapeutic applications. PMID:26589505

  13. Improved performance of nanowire-quantum-dot-polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

    Science.gov (United States)

    Nadarajah, A.; Smith, T.; Könenkamp, R.

    2012-12-01

    We report a nanowire-quantum-dot-polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm-2 illumination.

  14. Reply to "Comment on 'Electrical Conductivity and Current-Voltage Characteristics of Individual Conducting Polymer PEDOT Nanowires'"

    Institute of Scientific and Technical Information of China (English)

    LONG Yun-Ze

    2009-01-01

    @@ Recently we reported electrical properties of an individual PEDOT nanowire.[1] Ohlckers and Pipinys[2]suggested that the temperature-behavior of Ⅰ- Ⅴcurves and resistance can be described in the framework of a phonon-assisted tunneling (PhAT) model.

  15. Nanowire sensors and arrays for chemical/biomolecule detection

    Science.gov (United States)

    Yun, Minhee; Lee, Choonsup; Vasquez, Richard P.; Ramanathan, K.; Bangar, M. A.; Chen, W.; Mulchandan, A.; Myung, N. V.

    2005-01-01

    We report electrochemical growth of single nanowire based sensors using e-beam patterned electrolyte channels, potentially enabling the controlled fabrication of individually addressable high density arrays. The electrodeposition technique results in nanowires with controlled dimensions, positions, alignments, and chemical compositions. Using this technique, we have fabricated single palladium nanowires with diameters ranging between 75 nm and 300 nm and conducting polymer nanowires (polypyrrole and polyaniline) with diameters between 100 nm and 200 nm. Using these single nanowires, we have successfully demonstrated gas sensing with Pd nanowires and pH sensing with polypirrole nanowires.

  16. Simultaneous nano- and micro-scale control of nanofibrous microspheres self-assembled from star-shaped polymers

    Science.gov (United States)

    Zhang, Zhanpeng; Marson, Ryan L.; Ge, Zhishen; Glotzer, Sharon C.; Ma, Peter X.

    2015-01-01

    The mechanism underlying the multi-scale self-assembly of star-shaped polymers into non-hollow, hollow, and spongy nanofibrous microspheres is reported. Star-shaped poly(L-lactic acid) polymers with varying arm-numbers and arm-lengths are synthesized, dissolved in tetrahydrofuran, emulsified in glycerol, and thermally-induced to phase separate, resulting in microspheres that are either smooth or fibrous on the nano-scale, and either non-hollow, hollow, or spongy on the micro-scale. Molecular architecture and the hydroxyl density are shown to control assembly and morphology at both nano- and micro-scales. Nanofibers form only when the arm length is sufficiently long, while an increase in hydroxyl density causes the microspheres to change from non-hollow to hollow to spongy. We demonstrate via both experiments of capping or doubling the hydroxyl end groups and dissipative particle dynamics simulations that the affinity of hydroxyl to glycerol is critical to stabilizing the micro-scale structure. A “phase diagram” was constructed for the six types of microspheres in relation to the molecular structures of the star-shaped polymers. The proposed mechanism explains how star-shaped polymers self-assemble into various microspheres, and guides us to simultaneously control both nano- and micro-features of the microspheres. PMID:26009995

  17. Thermo-reversible morphology and conductivity of a conjugated polymer network embedded in polymeric self-assembly

    Science.gov (United States)

    Han, Youngkyu; Carrillo, Jan-Michael Y.; Zhang, Zhe; Li, Yunchao; Hong, Kunlun; Sumpter, Bobby G.; Ohl, Michael; Paranthaman, Mariappan Parans; Smith, Gregory S.; Do, Changwoo

    Self-assembly of block copolymers provides opportunities to create nano hybrid materials, utilizing self-assembled micro-domains with a variety of morphology and periodic architectures as templates for functional nano-fillers. Here we report new progress towards the fabrication of a thermally responsive conducting polymer self-assembly made from a water-soluble poly(thiophene) derivative with short PEO side chains and Pluronic L62 solution in water. The structural and electrical properties of conjugated polymer-embedded nanostructures were investigated by combining SANS, SAXS, CGMD simulations, and impedance spectroscopy. The L62 solution template organizes the conjugated polymers by stably incorporating them into the hydrophilic domains thus inhibiting aggregation. The changing morphology of L62 during the micellar-to-lamellar phase transition defines the embedded conjugated polymer network. The conductivity is strongly coupled to the structural change of the templating L62 phase and exhibits thermally reversible behavior with no signs of quenching of the conductivity at high temperature. The research was sponsored by the Scientific User Facilities Division, Office of BES, U.S. DOE and Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC.

  18. V(2)O(5) nanowires with an intrinsic iodination activity leading to the formation of self-assembled melanin-like biopolymers

    NARCIS (Netherlands)

    F. Natalio; R. André; S.A. Pihan; M. Humanes; R. Wever; W. Tremel

    2011-01-01

    V2O5 nanowires act as biomimetic catalysts resembling vanadium haloperoxidases (V-HPO). The nanowires display iodinating activity as confirmed by a colorimetric assay using thymol blue (TB), UV/Vis spectrophotometry and mass spectrometry (FD-MS). In the presence of dopamine these nanowires catalyze

  19. RF/Microwave properties and applications of directly assembled nanotubes and nanowires: LDRD project 102662 final report.

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Theresa (The Pennyslvania State University, University Park, PA 16802); Vallett, Aaron (The Pennyslvania State University, University Park, PA 16802); Lee, Mark; Shaner, Eric Arthur; Jones, Frank E.; Talin, Albert Alec; Highstrete, Clark

    2006-11-01

    LDRD Project 102662 provided support to pursue experiments aimed at measuring the basic electrodynamic response and possible applications of carbon nanotubes and silicon nanowires at radiofrequency to microwave frequencies, approximately 0.01 to 50 GHz. Under this project, a method was developed to integrate these nanomaterials onto high-frequency compatible co-planar waveguides. The complex reflection and transmission coefficients of the nanomaterials was studied as a function of frequency. From these data, the high-frequency loss characteristics of the nanomaterials were deduced. These data are useful to predict frequency dependence and power dissipation characteristics in new rf/microwave devices incorporating new nanomaterials.

  20. High-Efficiency Solid-State Dye-Sensitized Solar Cells: Fast Charge Extraction through Self-Assembled 3D Fibrous Network of Crystalline TiO 2 Nanowires

    KAUST Repository

    Tétreault, Nicolas

    2010-12-28

    Herein, we present a novel morphology for solid-state dye-sensitized solar cells based on the simple and straightforward self-assembly of nanorods into a 3D fibrous network of fused single-crystalline anatase nanowires. This architecture offers a high roughness factor, significant light scattering, and up to several orders of magnitude faster electron transport to reach a near-record-breaking conversion efficiency of 4.9%. © 2010 American Chemical Society.

  1. Multi-colored fibers by self-assembly of DNA, histone proteins, and cationic conjugated polymers.

    Science.gov (United States)

    Wang, Fengyan; Liu, Zhang; Wang, Bing; Feng, Liheng; Liu, Libing; Lv, Fengting; Wang, Yilin; Wang, Shu

    2014-01-01

    The development of biomolecular fiber materials with imaging ability has become more and more useful for biological applications. In this work, cationic conjugated polymers (CCPs) were used to construct inherent fluorescent microfibers with natural biological macromolecules (DNA and histone proteins) through the interfacial polyelectrolyte complexation (IPC) procedure. Isothermal titration microcalorimetry results show that the driving forces for fiber formation are electrostatic and hydrophobic interactions, as well as the release of counterions and bound water molecules. Color-encoded IPC fibers were also obtained based on the co-assembly of DNA, histone proteins, and blue-, green-, or red- (RGB-) emissive CCPs by tuning the fluorescence resonance energy-transfer among the CCPs at a single excitation wavelength. The fibers could encapsulate GFP-coded Escherichia coli BL21, and the expression of GFP proteins was successfully regulated by the external environment of the fibers. These multi-colored fibers show a great potential in biomedical applications, such as biosensor, delivery, and release of biological molecules and tissue engineering.

  2. Fabrication of a molecularly imprinted polymer sensor by self-assembling monolayer/mediator system

    International Nuclear Information System (INIS)

    Detection of dopamine (DA) by using a molecularly imprinted polymer (MIP) which fabricated by the self-assembling monolayer (SAM)/mediator system was studied. The SAM was made by attaching thioglycolic acid (TGA) on a gold electrode and quercetin (Q) was selected as an electron transfer mediator in this system. Methyl methacrylate (MMA) was polymerized by photopolymerization with the addition of dopamine to form a MIP electrode. The MIP and non-MIP (NMIP) modified electrodes were identified by FTIR and scanning electrochemical microscopy (SECM) approach curves. DA was detected by an amperometric method at a constant potential of 0.45 V and obtained a sensitivity of 0.445 mA cm-2 M-1. The imprinting efficiency approaches infinity due to a non-reactive surface of NMIP. In the interference test, ascorbic acid contributed less than 12% of current response in the coexistence solution with DA and the performance is highly related to the concentration of template added during the fabrication process.

  3. Nanoparticle/Polymer assembled microcapsules with pH sensing property.

    Science.gov (United States)

    Zhang, Pan; Song, Xiaoxue; Tong, Weijun; Gao, Changyou

    2014-10-01

    The dual-labeled microcapsules via nanoparticle/polymer assembly based on polyamine-salt aggregates can be fabricated for the ratiometric intracellular pH sensing. After deposition of SiO2 nanoparticles on the poly(allylamine hydrochloride)/multivalent anionic salt aggregates followed by silicic acid treatment, the generated microcapsules are stable in a wide pH range (3.0 ∼ 8.0). pH sensitive dye and pH insensitive dye are simultaneously labeled on the capsules, which enable the ratiometric pH sensing. Due to the rough and positively charged surface, the microcapsules can be internalized by several kinds of cells naturally. Real-time measurement of intracellular pH in several living cells shows that the capsules are all located in acidic organelles after being taken up. Furthermore, the negatively charged DNA and dyes can be easily encapsulated into the capsules via charge interaction. The microcapsules with combination of localized pH sensing and drug loading abilities have many advantages, such as following the real-time transportation and processing of the carriers in cells. PMID:25081194

  4. Self-assembly of monodisperse polymer microspheres from PPQ-b-PEG rod-coil block copolymers in selective solvents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xueao; CHEN Ke; XIE Kai; LONG Yongfu

    2005-01-01

    Poly(phenylquinoline)-block-poly(ethylene glycol)(PPQ-b-PEG) rod-coil block copolymers possess the self-assembly behavior in selective solvents. The copolymers in the mixed solvents of V(trifluoroacetic acid, TFA):V(dichloromethane, DCM)=1:1 can self-assemble into polymer hollow microspheres with diameters of a few micrometers. The polymer hollow microspheres are monodisperse, and the diameters of them increase with an increased polymerization degree of the PPQ rigid-rod block. The solution concentration has no effect on the microsphere diameter, but spherical surface shows burrs when the solution concentration is too low. It has been found that the obtained dilute solution has the strongest absorption peak at 376 nm and strongest emission peak at 604 nm by the spectroscopy analysis.

  5. Purification and processing of carbon nanotubes using self-assembly and selective interaction with a semiconjugated polymer

    Science.gov (United States)

    Fournet, Patrick; McCarthy, Brendan; Dalton, Alan B.; Coleman, Jonathan N.; Murphy, Robert J.; Stephan, Christophe; Lefrant, Serge; Bernier, Patrick; Byrne, Hugh J.; Blau, Werner J.

    2001-12-01

    A new route for nanotube-based applications in molecular electronics was developed. Individual polymer strands were assembled onto single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) by mechanical agitation. The SWNT hybrid systems have been characterized by electron microscopy (TEM, STM), optical absorption and Raman spectroscopy and a fully nondestructive technique, using electron paramagnetic resonance (EPR), has been developed to estimate the purity of MWNT soot and hybrids. It is demonstrated that solutions of the polymer are capable of suspending nanotubes indefinitely while the majority of the accompanying amorphous graphite precipitates out of solution. Electron microscopy and Raman scattering indicate that through an intercalation process, the ropes of SWNT are destroyed, resulting in individual nanotubes being well dispersed within the polymer matrix. Moreover, Raman and absorption studies suggest that the polymer interacts preferentially with nanotubes of specific diameters or a range of diameters. STM studies showed that the chiral angle of the underlying nanotube is reflected in the polymer coating, demonstrating that the lattice structure of the SWNT templates the ordering in the coating. This could lead to design of specific polymer architectures for selection of desired chiral angles, and hence specific electronic properties.

  6. Probing the self-assembled nanostructures of functional polymers with synchrotron grazing incidence X-ray scattering.

    Science.gov (United States)

    Ree, Moonhor

    2014-05-01

    For advanced functional polymers such as biopolymers, biomimic polymers, brush polymers, star polymers, dendritic polymers, and block copolymers, information about their surface structures, morphologies, and atomic structures is essential for understanding their properties and investigating their potential applications. Grazing incidence X-ray scattering (GIXS) is established for the last 15 years as the most powerful, versatile, and nondestructive tool for determining these structural details when performed with the aid of an advanced third-generation synchrotron radiation source with high flux, high energy resolution, energy tunability, and small beam size. One particular merit of this technique is that GIXS data can be obtained facilely for material specimens of any size, type, or shape. However, GIXS data analysis requires an understanding of GIXS theory and of refraction and reflection effects, and for any given material specimen, the best methods for extracting the form factor and the structure factor from the data need to be established. GIXS theory is reviewed here from the perspective of practical GIXS measurements and quantitative data analysis. In addition, schemes are discussed for the detailed analysis of GIXS data for the various self-assembled nanostructures of functional homopolymers, brush, star, and dendritic polymers, and block copolymers. Moreover, enhancements to the GIXS technique are discussed that can significantly improve its structure analysis by using the new synchrotron radiation sources such as third-generation X-ray sources with picosecond pulses and partial coherence and fourth-generation X-ray laser sources with femtosecond pulses and full coherence.

  7. Assembly Properties of an Alanine-Rich, Lysine-Containing Peptide and the Formation of Peptide/Polymer Hybrid Hydrogels

    OpenAIRE

    Grieshaber, Sarah E.; Nie, Ting; Yan, Congqi; Zhong, Sheng; Teller, Sean S.; Clifton, Rodney J.; Pochan, Darrin J.; Kiick, Kristi L.; Jia, Xinqiao

    2011-01-01

    We are interested in developing peptide/polymer hybrid hydrogels that are chemically diverse and structurally complex. Towards this end, an alanine-based peptide doped with charged lysines with a sequence of (AKA3KA)2 (AK2) was selected from the crosslinking regions of the natural elastin. Pluronic® F127, known to self-assemble into defined micellar structures, was employed as the synthetic building blocks. Fundamental investigations on the environmental effects on the secondary structure and...

  8. Self-Assembly of Telechelic Tyrosine End-Capped PEO and Poly(alanine) Polymers in Aqueous Solution.

    Science.gov (United States)

    Kirkham, Steven; Castelletto, Valeria; Hamley, Ian William; Reza, Mehedi; Ruokolainen, Janne; Hermida-Merino, Daniel; Bilalis, Panayiotis; Iatrou, Hermis

    2016-03-14

    The self-assembly in aqueous solution of three novel telechelic conjugates comprising a central hydrophilic polymer and short (trimeric or pentameric) tyrosine end-caps has been investigated. Two of the conjugates have a central poly(oxyethylene) (polyethylene oxide, PEO) central block with different molar masses. The other conjugate has a central poly(L-alanine) (PAla) sequence in a purely amino-acid based conjugate. All three conjugates self-assemble into β-sheet based fibrillar structures, although the fibrillar morphology revealed by cryogenic-TEM is distinct for the three polymers--in particular the Tyr5-PEO6k-Tyr5 forms a population of short straight fibrils in contrast to the more diffuse fibril aggregates observed for Tyr5-PEO2k-Tyr5 and Tyr3-PAla-Tyr3. Hydrogel formation was not observed for these samples (in contrast to prior work on related systems) up to quite high concentrations, showing that it is possible to prepare solutions of peptide-polymer-peptide conjugates with hydrophobic end-caps without conformational constraints associated with hydrogelation. The Tyr5-PEO6k-Tyr5 shows significant PEO crystallization upon drying in contrast to the Tyr5-PEO2k-Tyr5 conjugate. Our findings point to the remarkable ability of short hydrophobic peptide end groups to modulate the self-assembly properties of polymers in solution in model peptide-capped "associative polymers". Retention of fluidity at high conjugate concentration may be valuable in potential future applications of these conjugates as bioresponsive or biocompatible materials, for example exploiting the enzyme-responsiveness of the tyrosine end-groups. PMID:26867986

  9. Understanding the Structure of Reversible Coordination Polymers Based on Europium in Electrostatic Assemblies Using Time-Resolved Luminescence.

    Science.gov (United States)

    Xu, Limin; Xie, Mengqi; Huang, Jianbin; Yan, Yun

    2016-06-14

    In situ characterization of the structure of reversible coordination polymers remains a challenge because of their dynamic and concentration-responsive nature. It is especially difficult to determine these structures in their self-assemblies where their degree of polymerization responds to the local concentration. In this paper, we report on the structure of reversible lanthanide coordination polymers in electrostatic assemblies using time-resolved luminescence (TRL) measurement. The reversible coordinating system is composed of the bifunctional ligand 1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane (L2EO4) and europium ion Eu(3+). Upon mixing with the positively charged diblock copolymer poly(2-vinylpyridine)-b-poly(ethylene oxide) (P2VP41-b-PEO205), electrostatic polyion micelles are formed and the negatively charged L2EO4-Eu coordination complex simultaneously transforms into coordination "polymers" in the micellar core. By virtue of the water-sensitive luminescence of Eu(3+), we are able to obtain the structural information of the L2EO4-Eu coordination polymers before and after the formation of polyion micelles. Upon analyzing the fluorescence decay curves of Eu(3+) before and after micellization, the fraction of Eu(3+) fully coordinated with L2EO4 is found to increase from 32 to 83%, which verifies the occurrence of chain extension of the L2EO4-Eu coordination polymers in the micellar core. Our work provides a qualitative picture for the structure change of reversible coordination polymers, which allows us to look into these "invisible" structures.

  10. Self-assembly of CdTe nanocrystals at the water/oil interface by amphiphilic hyperbranched polymers

    International Nuclear Information System (INIS)

    A general strategy for realizing the self-assembly of aqueous CdTe nanocrystals (NCs) at the water/oil interface by means of an amphiphilic core-shell hyperbranched polymer has been proposed. Aqueous CdTe NCs were firstly transferred into the chloroform phase in the presence of palmityl chloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC), and then self-assembled at the water/chloroform interface by decreasing the pH value of the aqueous phase or introducing α-CDs to the aqueous phase. The resulting CdTe/HPAMAM-PC self-assembly film was characterized by fluorescence microscopy, UV-vis, PL, TEM, EDS, FT-IR, DSC and TGA.

  11. Structure and Electronic Properties of Polymer Chains and Graphene Nanoribbon Formed by Molecular Self-Assembly on Au(111)

    Science.gov (United States)

    Ma, Chuanxu; Fuentes-Cabrera, Miguel A.; Sumpter, Bobby G.; Hong, Kunlun; Li, An-Ping; Xiao, Zhongcan; Lu, Wenchang; Bernholc, J.

    Graphene nanoribbons (GNRs) with bandgaps are promising building blocks for ultra-fast electronics. Bottom-up synthesis of GNRs from aromatic hydrocarbon molecules has been proven to be an effective way to control GNR's width with atomically precise edge structures. Using scanning tunneling microscopy (STM), we study the formation of both linear polymer chains and narrow GNRs in the bottom-up self-assembly process with the DBBA molecules as the precursor on Au(111). The linear polymer chains are formed after the deposition of DBBA and 200 °C annealing for 30 min. The polymers can be converted to 7-AGNRs (seven-carbon wide armchair GNRs) after 400 °C annealing. Interestingly, second-layer polymer is seen to survive on the GNRs during the annealing process. This result indicates that the Au(111) substrate plays an important role in the dehydrogenation process and the formation of GNRs, which is confirmed by our DFT calculations. Electronically, the polymers show a bandgap of 3.4 eV, much larger than that of GNRs. After annealing at 500 °C for 30 min, wider GNRs can form: 14-AGNR, 21-AGNR. The 7-AGNR shows a typical edge state at -1.1 eV, while for 14-AGNR it is at -1.35 eV. Moreover, junctions of GNRs with different widths can be formed with pronounced boundary states.

  12. Electrostatic Assembly of Polymers and Nanoparticles at Liquid-Liquid Interfaces

    Science.gov (United States)

    Hoagland, David

    The electrostatic attraction between charged solutes on opposite sides of the interface between immiscible liquids offers an efficient route to the self-assembly of two-dimensional films. As implemented by us, a hydrophobic polymer with amine end(s) or block(s) is presented in an oil phase, and a negatively charged nanoparticle is presented in an aqueous phase; both solutes are insoluble in the opposite phase but efficiently driven to the liquid-liquid interface by mutual electrostatically attraction to the solute in the opposite phase. Depending on experimental conditions (salt concentration, pH, solute concentrations, etc.), a continuous, nanoscopically thin composite film builds at the oil-water interface over the timescale of minutes, often accompanied by a dramatic reduction of interfacial tension akin to that observed for a surfactant. Film formation and properties by the new route will be discussed, as principally probed through pendant drop interfacial tensiometry and pendant drop interfacial rheometry. Components of model system are toluene-dissolved amine end-capped polystyrene and water-dispersed acid-treated carbon nanotubes or citrate-treated gold nanospheres. Film structures are complicated, as are crucial electrostatic interactions near the interface. With amine end-capped polystyrene partnered with acid-treated carbon nanotubes, high pH (above 5) and high polystyrene molecular weight (above 5000 g/mol) strongly hinder film formation. These films, which are liquid-like, show two viscoelastic relaxations, a fast relaxation (about 10 s) associated with polystyrene chain rearrangements (slightly impacted by carbon nanotube association) and a slow relaxation (about 20 min) associated with polystyrene adsorption/desorption; at intermediate times (or frequencies), the two-dimensional storage and loss moduli follow approximately the same power law dependences. Support by NSF through the Univ. of Massachusetts MRSEC.

  13. Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

    Science.gov (United States)

    Zhao, Dan; Di Nicola, Matteo; Khani, Mohammad M; Jestin, Jacques; Benicewicz, Brian C; Kumar, Sanat K

    2016-09-14

    We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix. PMID:27502154

  14. Multifunctional metal-polymer nanoagglomerates from single-pass aerosol self-assembly

    Science.gov (United States)

    Byeon, Jeong Hoon

    2016-08-01

    In this study, gold (Au)-iron (Fe) nanoagglomerates were capped by a polymer mixture (PM) consisting of poly(lactide-co-glycolic acid), protamine sulfate, and poly-l-lysine via floating self-assembly in a single-pass aerosol configuration as multibiofunctional nanoplatforms. The Au-Fe nanoagglomerates were directly injected into PM droplets (PM dissolved in dichloromethane) in a collison atomizer and subsequently heat-treated to liberate the solvent from the droplets, resulting in the formation of PM-capped Au-Fe nanoagglomerates. Measured in vitro, the cytotoxicities of the nanoagglomerates (>98.5% cell viability) showed no significant differences compared with PM particles alone (>98.8%), thus implying that the nanoagglomerates are suitable for further testing of biofunctionalities. Measurements of gene delivery performance revealed that the incorporation of the Au-Fe nanoagglomerates enhanced the gene delivery performance (3.2 × 106 RLU mg‑1) of the PM particles alone (2.1 × 106 RLU mg‑1), which may have been caused by the PM structural change from a spherical to a hairy structure (i.e., the change followed the agglomerated backbone). Combining the X-ray-absorbing ability of Au and the magnetic property of Fe led to magnetic resonance (MR)-computed tomography (CT) contrast ability in a phantom; and the signal intensities [which reached 64 s‑1 T2-relaxation in MR and 194 Hounsfield units (HUs) in CT at 6.0 mg mL‑1] depended on particle concentration (0.5–6.0 mg mL‑1).

  15. Self-Assembly of Cluster-Based Nanoscopic Supramolecules into One-Dimensional Coordination Polymers

    Directory of Open Access Journals (Sweden)

    Jian-Jun Zhang

    2009-01-01

    (2, and [(4,4′-bpe(Mn(Salen(H2O2]{(4,4′-bpe2[(Mn(Salen(MeOH2(Mn(Salen2(Nb6Cl12(CN6][(Mn(Salen2(Nb6Cl12(CN6]}·16H2O (3. Single crystal X-ray diffraction analyses show that the frameworks of the three coordination polymers are built of heterotrimeric and/or heteropentameric supramolecular species linked by ditopic organic ligands. The framework of 1 consists of anionic chains built of heterotrimeric dianions [(Mn(Salen2(Nb6Cl12(CN6]2− (T linked by 4,4′-dpyo. The chains run along two directions ([0 2 −2] and [0 3 3] leading to the formation of channels along the crystallographic (a direction where the cations [Mn(Salen(S2]+ and solvent molecules are located. Also, 2 was reported earlier, it possesses a neutral 1D chain built of neutral heterpentameric supramolecules: [(Mn(7‐MeSalen2(Mn(7‐MeSalen(S2(Nb6Cl12(CN6] (P linked by 4,4′-bpe ligands. Hydrogen bonds between non-bridging cyanide ligands and coordinated solvent molecules connect the chains into 2D hydrogen-bonded frameworks. Finally, 3 features an anionic chain, built of alternating heterotrimers [(Mn(Salen2(Nb6Cl12(CN6]2− and heteropentamers [(Mn(Salen(S2(Mn(Salen2(Nb6Cl12(CN6] linked by the organic spacer 4,4′-bpe. The anionic charge is compensated by the in situe-assembled [Mn(Salen(S(4,4′‐bpeMn(Salen(S]2+ dimers. Magnetic measurements reveal that the Mn(III ions are well isolated and only weak magnetic interactions are observed. The thermal stability of the three compounds was investigated.

  16. Biological Sensing and DNA Templated Electronics Using Conjugated Polymers

    OpenAIRE

    Björk, Per

    2007-01-01

    Conjugated polymers have been found useful in a wide range of applications such as solar cells, sensor elements and printed electronics, due to their optical and electronic properties. Functionalization with charged side chains has enabled water solubility, resulting in an enhanced interaction with biomolecules. This thesis focus on the emerging research fields, where these conjugated polyelectrolytes (CPEs) are combined with biomolecules for biological sensing and DNA nanowire assembling. CP...

  17. Water-soluble, luminescent ZnTe quantum dots: supersaturation-controlled synthesis and self-assembly into nanoballs, nanonecklaces and nanowires.

    Science.gov (United States)

    Patra, Sovan Kumar; Bhushan, Bhavya; Priyam, Amiya

    2016-03-01

    A supersaturation-controlled aqueous synthesis route has been developed for ZnTe quantum dots (QDs) with high monodispersity, size tunability, stability, band-edge luminescence (full-width at half-maximum (FWHM) 10-12 nm) and negligibly small Stokes' shift (2-4 nm). The degree of supersaturation of the initial reaction mixture was varied by increasing the reagent concentration, but keeping the molar ratio Zn(2+) : thioglycolic acid : Te(2-) constant at 1 : 2.5 : 0.5. For a 10× increase in supersaturation, the photoluminescence (PL) peak underwent a 50 nm blue shift from 330 to 280 nm at pH 6. The effect was more pronounced at pH 12, where the PL peak blue-shifted by 100 nm from 327 to 227 nm. Concomitantly, the FWHM was also reduced to a low value of 10 nm, indicating high monodispersity. For a 10× change in supersaturation, the particle size decreased by 63% (from 2.2 to 0.8 nm) at pH 12, whereas it changed by 19% (from 2.1 to 1.7 nm) at pH 6. High-resolution transmission electron microscopy and selected area electron diffraction data further revealed that the QDs synthesized at higher supersaturation had a better crystallinity. These QDs exhibited the unique property of undergoing isotropic and anisotropic self-assembly, which resulted in a blue shift and a red shift in the absorption and PL spectra, respectively. Isotropic assembly into spherical nanoballs (100 nm diameter, 1 nm inter-QD separation) occurred when the QDs were stored at pH 12 for 3 weeks at room temperature. The nanoballs further self-assembled into a 'pearl necklace' arrangement. On the partial removal of the capping agents, the QDs self-organized anisotropically into nanowires (1.3 μm long and 4.6 nm in diameter). The self-assembled nanostructures showed exciton-exciton coupling and excellent PL properties, which may be useful in enhanced optoelectronics, photovoltaics and biochemical sensing. PMID:26830257

  18. A density functional study of silver clusters on a stepped graphite surface: formation of self-assembled nano-wires.

    Science.gov (United States)

    Singh, Akansha; Sen, Prasenjit

    2015-05-21

    Adsorption and diffusion of silver adatoms and clusters containing up to eight atoms on an HOPG substrate with an armchair step are studied using density functional methods. Step edges act as attractive sinks for adatoms and clusters. The diffusion barrier of an Ag adatom along the step edge is much larger than that on a clean terrace. At zero temperature, Ag clusters either distort or dissociate by forming covalent bonds with the edge C atoms. At 600 K, Ag5 and Ag8 clusters diffuse to the step edges, and then break up so as to maximize Ag-C bonds. The Ag atoms try to form a nanowire structure along the step edge. At such high temperatures, diffusion of clusters along the step edge involves diffusion of individual Ag atoms not bonded to the edge C atoms. Assumption of complete immobility of clusters trapped at step edges in the Gates-Robins model is not valid at high temperatures in this particular system. PMID:25903308

  19. A supramolecular Janus hyperbranched polymer and its photoresponsive self-assembly of vesicles with narrow size distribution.

    Science.gov (United States)

    Liu, Yong; Yu, Chunyang; Jin, Haibao; Jiang, Binbin; Zhu, Xinyuan; Zhou, Yongfeng; Lu, Zhongyuan; Yan, Deyue

    2013-03-27

    Herein, we report a novel Janus particle and supramolecular block copolymer consisting of two chemically distinct hyperbranched polymers, which is coined as Janus hyperbranched polymer. It is constructed by the noncovalent coupling between a hydrophobic hyperbranched poly(3-ethyl-3-oxetanemethanol) with an apex of an azobenzene (AZO) group and a hydrophilic hyperbranched polyglycerol with an apex of a β-cyclodextrin (CD) group through the specific AZO/CD host-guest interactions. Such an amphiphilic supramolecular polymer resembles a tree together with its root very well in the architecture and can further self-assemble into unilamellar bilayer vesicles with narrow size distribution, which disassembles reversibly under the irradiation of UV light due to the trans-to-cis isomerization of the AZO groups. In addition, the obtained vesicles could further aggregate into colloidal crystal-like close-packed arrays under freeze-drying conditions. The dynamics and mechanism for the self-assembly of vesicles as well as the bilayer structure have been disclosed by a dissipative particle dynamics simulation. PMID:23464832

  20. Block copolymer assisted self-assembly of nanoparticles into Langmuir–Blodgett films: Effect of polymer concentration

    Energy Technology Data Exchange (ETDEWEB)

    Martín-García, Beatriz; Velázquez, M. Mercedes, E-mail: mvsal@usal.es

    2013-08-15

    We propose to use the self-assembly ability of a block copolymer to obtain CdSe quantum dots (QDs) structures of different morphology. The methodology proposed consist in transferring mixed Langmuir monolayers of QDs and the polymer poly (styrene-co-maleic anhydride) partial 2 buthoxy ethyl ester cumene terminated, PS-MA-BEE onto mica by the Langmuir–Blodgett (LB) methodology. The morphology of the LB films was analyzed by AFM and TEM measurements. Our results show that it is possible to modulate the self-assembly process by modifying the composition of the mixed Langmuir monolayer precursor of the LB film. The different morphologies are interpreted according to two different dewetting mechanisms, growth of holes and spinodal-like dewetting. The growth of holes dewetting process is driven by gravitatory effects and was observed for LB films obtained by transferring Langmuir monolayer of the smallest elasticity values in which the polymer is in brush conformation. The spinodal dewetting mechanism prevailed when the Langmuir monolayer presents the highest elasticity values. - Graphical abstract: Display Omitted - Highlights: • Effect of the surface composition on the LB films architecture. • QDs/polymer LB films morphology interpreted in terms of dewetting mechanism. • The dewetting mechanism depends on the Langmuir monolayer state.

  1. Directed self assembly of polymer/nanoparticle composites controlled by internal and external fields

    OpenAIRE

    Lewin, Christian

    2016-01-01

    In this thesis the influence of solvent vapor annealing and external electric fields on poly-mer / nanoparticle composites has been investigated. Gold nanoparticle composite films were prepared with an SV block copolymer polymer as well as with PS and PMMA homopolymers and PS:PMMA blends.In the first part of this thesis SV block copolymer polymer / gold nanoparticle composite films were exposed to an external electric field. In situ SAXS measurements were performed to investigate the kinetics...

  2. Heterojunction nanowires having high activity and stability for the reduction of oxygen: formation by self-assembly of iron phthalocyanine with single walled carbon nanotubes (FePc/SWNTs).

    Science.gov (United States)

    Zhu, Jia; Jia, Nana; Yang, Lijun; Su, Dong; Park, Jinseong; Choi, YongMan; Gong, Kuanping

    2014-04-01

    A self-assembly approach to preparing iron phthalocyanine/single-walled carbon nanotube (FePc/SWNT) heterojunction nanowires as a new oxygen reduction reaction (ORR) electrocatalyst has been developed by virtue of water-adjusted dispersing in 1-cyclohexyl-pyrrolidone (CHP) of the two components. The FePc/SWNT nanowires have a higher Fermi level compared to pure FePc (d-band center, DFT=-0.69 eV versus -0.87 eV, respectively). Consequently, an efficient channel for transferring electron to the FePc surface is readily created, facilitating the interaction between FePc and oxygen, so enhancing the ORR kinetics. This heterojunction-determined activity in ORR illustrates a new stratagem to preparing non-noble ORR electrocatalysts of significant importance in constructing real-world fuel cells. PMID:24491331

  3. Heterojunction nanowires having high activity and stability for the reduction of oxygen: Formation by self-assembly of iron phthalocyanine with single walled carbon nanotubes (FePc/SWNTs)

    KAUST Repository

    Zhu, Jia

    2014-04-01

    A self-assembly approach to preparing iron phthalocyanine/single-walled carbon nanotube (FePc/SWNT) heterojunction nanowires as a new oxygen reduction reaction (ORR) electrocatalyst has been developed by virtue of water-adjusted dispersing in 1-cyclohexyl-pyrrolidone (CHP) of the two components. The FePc/SWNT nanowires have a higher Fermi level compared to pure FePc (d-band center, DFT. =. -0.69. eV versus -0.87. eV, respectively). Consequently, an efficient channel for transferring electron to the FePc surface is readily created, facilitating the interaction between FePc and oxygen, so enhancing the ORR kinetics. This heterojunction-determined activity in ORR illustrates a new stratagem to preparing non-noble ORR electrocatalysts of significant importance in constructing real-world fuel cells. © 2013 Elsevier Inc.

  4. Biocompatible polyester macroligands: new subunits for the assembly of star-shaped polymers with luminescent and cleavable metal cores.

    Science.gov (United States)

    Corbin, P S; Webb, M P; McAlvin, J E; Fraser, C L

    2001-01-01

    The synthesis of a series of star-shaped, biocompatible polyesters--polylactides (PLAs), polycaprolactones (PCLs), and various copolymer analogues--with either labile iron(II) tris-bipyridyl or luminescent ruthenium(II) tris-bipyridyl cores is described. These polymers were readily assembled by a convergent, metal-template-assisted approach that entailed the synthesis of bipyridine (bpy) ligands incorporating PLA- and PCL-containing arms and subsequent chelation of the "macroligands" to iron(II) or ruthenium(II). Specifically, the polyester macroligands bpyPLA(2) and bpyPCL(2) were prepared by a stannous octoate catalyzed ring-opening polymerization of DL- or L-lactide and epsilon-caprolactone, using bis(hydroxymethyl)-2,2'-bipyridine as the initiator. Copolymers bpy(PCL-PLA)(2) and bpy(PLA-PCL)(2) were generated in an analogous manner using bpyPLA(2) and bpyPCL(2) as macroinitiators. Polymers with narrow molecular weight distributions and with molecular weights close to values expected based upon monomer/initiator loading were produced. The macroligands were subsequently chelated to iron(II) to afford six-armed, iron-core star polymers, which were characterized by UV-vis and (1)H NMR spectroscopy. Estimated chelation efficiencies for formation of the star polymers (M(n) calcd: 20-240 kDa) were high, as determined by UV-vis spectral analysis. Within the molecular weight range investigated, differential scanning calorimetry and thermogravimetric analysis revealed that the small amounts of metal in the polyester stars and differences in polymer architecture had little effect on the thermal properties of the PLA/PCL materials. However, thin films of the red-violet colored iron-core stars exhibited reversible, thermochromic bleaching. Solutions and films of the polymers also responded (with color loss) to a variety of chemical stimuli (e.g., acid, base, peroxides, ammonia), thus revealing potential for use in diverse sensing applications. Likewise, the polyester

  5. Direct laser fabrication of nanowires on semiconductor surfaces

    Science.gov (United States)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    Periodic nanowires are observed from (001) orientation of Si and GaAs when the surfaces are irradiated interferentially by high power laser pulses. These nanowires are self-assembled and can be strain-free while their period is consistent with interference period. The nanowire morphologies are studied by atomic force microscopy. The observed period between nanowires depends on the wavelengths used and interference angle. The nanowire width increases with laser intensity. The narrowest nanowires observed have the width smaller than 20 nm, which is more than 10 times smaller than the interference period.

  6. Redox-Robust Pentamethylferrocene Polymers and Supramolecular Polymers, and Controlled Self-Assembly of Pentamethylferricenium Polymer-Embedded Ag, AgI, and Au Nanoparticles.

    Science.gov (United States)

    Gu, Haibin; Ciganda, Roberto; Castel, Patricia; Vax, Amélie; Gregurec, Danijela; Irigoyen, Joseba; Moya, Sergio; Salmon, Lionel; Zhao, Pengxiang; Ruiz, Jaime; Hernández, Ricardo; Astruc, Didier

    2015-12-01

    We report the first pentamethylferrocene (PMF) polymers and the redox chemistry of their robust polycationic pentamethylferricenium (PMFium) analogues. The PMF polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a PMF-containing norbornene derivative by using the third-generation Grubbs ruthenium metathesis catalyst. Cyclic voltammetry studies allowed us to determine confidently the number of monomer units in the polymers through the Bard-Anson method. Stoichiometric oxidation by using ferricenium hexafluorophosphate quantitatively and instantaneously provided fully stable (even in aerobic solutions) blue d(5) Fe(III) metallopolymers. Alternatively, oxidation of the PMF-containing polymers was conducted by reactions with Ag(I) or Au(III) , to give PMFium polymer-embedded Ag and Au nanoparticles (NPs). In the presence of I2 , oxidation by using Ag(I) gave polymer-embedded Ag/AgI NPs and AgNPs at the surface of AgI NPs. Oxidation by using Au(III) also produced an Au(I) intermediate that was trapped and characterized. Engineered single-electron transfer reactions of these redox-robust nanomaterial precursors appear to be a new way to control their formation, size, and environment in a supramolecular way.

  7. Tube-graft-Sheet Nano-Objects Created by A Stepwise Self-Assembly of Polymer-Polyoxometalate Hybrids.

    Science.gov (United States)

    Tang, Jing; Li, Xue-Ying; Wu, Han; Ren, Li-Jun; Zhang, Yu-Qi; Yao, Hai-Xia; Hu, Min-Biao; Wang, Wei

    2016-01-19

    In this work, we report the preparation of complex nano-objects by means of a stepwise self-assembly of two polymer-polyoxometalate hybrids (PPHs) in solution. The PPHs are designed and synthesized by tethering two linear poly(ε-caprolactone)s (PCL) of different molecular weights (MW) on a complex of a Wells-Dawson-type polyoxometalate (POM) cluster and its countraions. The higher MW PCL-POM self-assembled into nanosheets, while the lower MW PCL-POM assembled into nanotubes just by altering the ratio of water in the DMF-water mixed solvent system. The two nano-objects have a similar membrane structure in which a PCL layer is sandwiched by the two POM-based complex layers. The PCL layer in the nanosheets is semicrystalline, while the PCL layer in the nanotubes is amorphous. We further exploited this MW-dependence to self-assemble the nanotubes on the nanosheet edges to create complex tube-graft-sheet nano-objects. We found that the nanotubes nucleate on the four {110} faces of the PCL crystal and then further grow along the crystallographic b-axis of the PCL crystal. Our findings offer hope for the further development of nano-objects with increasing complexity.

  8. Silver Nanowire-IZO-Conducting Polymer Hybrids for Flexible and Transparent Conductive Electrodes for Organic Light-Emitting Diodes

    Science.gov (United States)

    Yun, Ho Jun; Kim, Se Jung; Hwang, Ju Hyun; Shim, Yong Sub; Jung, Sun-Gyu; Park, Young Wook; Ju, Byeong-Kwon

    2016-01-01

    Solution-processed silver nanowire (AgNW) has been considered as a promising material for next-generation flexible transparent conductive electrodes. However, despite the advantages of AgNWs, some of their intrinsic drawbacks, such as large surface roughness and poor interconnection between wires, limit their practical application in organic light-emitting diodes (OLEDs). Herein, we report a high-performance AgNW-based hybrid electrode composed of indium-doped zinc oxide (IZO) and poly (3,4-ethylenediowythiophene):poly(styrenesulfonate) [PEDOT:PSS]. The IZO layer protects the underlying AgNWs from oxidation and corrosion and tightly fuses the wires together and to the substrate. The PEDOT:PSS effectively reduces surface roughness and increases the hybrid films’ transmittance. The fabricated electrodes exhibited a low sheet resistance of 5.9 Ωsq−1 with high transmittance of 86% at 550 nm. The optical, electrical, and mechanical properties of the AgNW-based hybrid films were investigated in detail to determine the structure-property relations, and whether optical or electrical properties could be controlled with variation in each layer’s thickness to satisfy different requirements for different applications. Flexible OLEDs (f-OLEDs) were successfully fabricated on the hybrid electrodes to prove their applicability; their performance was even better than those on commercial indium doped tin oxide (ITO) electrodes. PMID:27703182

  9. Stable and robust nanotubes formed from self-assembled polymer membranes

    Science.gov (United States)

    Helmerson, Kristian; Reiner, Joseph E.; Kishore, Rani B.; Jofre, Ana; Allegrini, Maria; Pfefferkorn, Candace; Wells, Jeffrey M.

    2006-08-01

    We create long polymer nanotubes by directly pulling on the membrane of polymersomes using either optical tweezers or a micropipette. The polymersomes are composed of amphiphilic diblock copolymers and the nanotubes formed have an aqueous core connected to the aqueous interior of the polymersome. We stabilize the pulled nanotubes by subsequent chemical cross-linking. The cross-linked nanotubes are extremely robust and can be moved to another medium for use elsewhere. We demonstrate the ability to form networks of polymer nanotubes and polymersomes by optical manipulation. The aqueous core of the polymer nanotubes together with their robust character makes them interesting candidates for nanofluidics and other applications in biotechnology.

  10. Interfacial Rheology of Hydrogen-Bonded Polymer Multilayers Assembled at Liquid Interfaces: Influence of Anchoring Energy and Hydrophobic Interactions.

    Science.gov (United States)

    Le Tirilly, Sandrine; Tregouët, Corentin; Reyssat, Mathilde; Bône, Stéphane; Geffroy, Cédric; Fuller, Gerald; Pantoustier, Nadège; Perrin, Patrick; Monteux, Cécile

    2016-06-21

    We study the 2D rheological properties of hydrogen-bonded polymer multilayers assembled directly at dodecane-water and air-water interfaces using pendant drop/bubble dilation and the double-wall ring method for interfacial shear. We use poly(vinylpyrrolidone) (PVP) as a proton acceptor and a series of polyacrylic acids as proton donors. The PAA series of chains with varying hydrophobicity was fashioned from poly(acrylic acid), (PAA), polymethacrylic acid (PMAA), and a homemade hydrophobically modified polymer. The latter consisted of a PAA backbone covalently grafted with C12 moieties at 1% mol (referred to as PAA-1C12). Replacing PAA with the more hydrophobic PMAA provides a route for combining hydrogen bonding and hydrophobic interactions to increase the strength and/or the number of links connecting the polyacid chains to PVP. This systematic replacement allows for control of the ability of the monomer units inside the absorbed polymer layer to reorganize as the interface is sheared or compressed. Consequently, the interplay of hydrogen bonding and hydrophobic interactions leads to control of the resistance of the polymer multilayers to both shear and dilation. Using PAA-1C12 as the first layer improves the anchoring energy of a few monomers of the chain without changing the strength of the monomer-monomer contact in the complex layer. In this way, the layer does not resist shear but resists compression. This strategy provides the means for using hydrophobicity to control the interfacial dynamics of the complexes adsorbed at the interface of the bubbles and droplets that either elongate or buckle upon compression. Moreover, we demonstrate the pH responsiveness of these interfacial multilayers by adding aliquots of NaOH to the acidic water subphase surrounding the bubbles and droplets. Subsequent pH changes can eventually break the polymer complex, providing opportunities for encapsulation/release applications. PMID:27176147

  11. Ultra-Thin Self-Assembled Protein-Polymer Membranes : A New Pore Forming Strategy

    NARCIS (Netherlands)

    van Rijn, Patrick; Tutus, Murat; Kathrein, Christine; Mougin, Nathalie C.; Park, Hyunji; Hein, Christopher; Schuerings, Marco P.; Boeker, Alexander

    2014-01-01

    Self-assembled membranes offer a promising alternative for conventional membrane fabrication, especially in the field of ultrafiltration. Here, a new pore-making strategy is introduced involving stimuli responsive proteinpolymer conjugates self-assembled across a large surface area using dryingmedia

  12. Two-Dimensional Electronic Excitations in Self-Assembled Conjugated Polymer Nanocrystals

    Science.gov (United States)

    Österbacka, R.; An, C. P.; Jiang, X. M.; Vardeny, Z. V.

    2000-02-01

    Several spectroscopic methods were applied to study the characteristic properties of the electronic excitations in thin films of regioregular and regiorandom polythiophene polymers. In the regioregular polymers, which form two-dimensional lamellar structures, increased interchain coupling strongly influences the traditional one-dimensional electronic properties of the polymer chains. The photogenerated charge excitations (polarons) show two-dimensional delocalization that results in a relatively small polaronic energy, multiple absorption bands in the gap where the lowest energy band becomes dominant, and associated infrared active vibrations with reverse absorption bands caused by electron-vibration interferences. The relatively weak absorption bands of the delocalized polaron in the visible and near-infrared spectral ranges may help to achieve laser action in nanocrystalline polymer devices using current injection.

  13. Linking homogeneous and heterogeneous enantioselective catalysis through a self-assembled coordination polymer.

    Science.gov (United States)

    García, José I; López-Sánchez, Beatriz; Mayoral, José A

    2008-11-01

    Combining the advantages of homogeneous and heterogeneous enantioselective catalysis is possible through self-supported copper coordination polymers, based on a new kind of ditopic chiral ligand bearing two azabis(oxazoline) moieties. When the coordination polymer is used to catalyze a cyclopropanation reaction, it becomes soluble in reaction conditions but precipitates after reaction completion, allowing easy recovery and efficient reuse in the same reaction up to 14 times.

  14. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    Directory of Open Access Journals (Sweden)

    Hongmei Luo

    2010-01-01

    Full Text Available We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses.

  15. Optimization and Characterization of Self-assembled Triblock Polymer Membranes with Chemically-Tunable Pore Walls for Nanofiltration Applications

    Science.gov (United States)

    Sargent, Jessica; Mulvenna, Ryan; Prato, Rafael; Weidman, Jacob; Phillip, William; Boudouris, Bryan

    2015-03-01

    The field of block polymer-based membranes for separation applications has grown considerably in the past several years. However, decreasing the domain sizes of these membranes to below 5 nm has proven to be a challenge in many instances. Here, we demonstrate that a triblock polymer, polyisoprene- b-polystyrene- b-poly(tert-butyl methacrylate) (PI-PS-PtBMA), can be utilized to form nanoporous membranes capable of high flux and high selectivity based on both size and chemical composition. By controlling the synthesis, solution self-assembly, and non-solvent induced phase separation of these polymers, a scalable fabrication process can produce thin-film membranes that feature monodisperse pores approaching 1 nm in diameter, tunable pore-wall chemistry, good mechanical stability, and chlorine degradation resistance. The PtBMA functionality can further be converted to a number of side chain functionalities through simple coupling chemistry to produce membranes with specific chemical and structural characteristics tailored to meet the needs of various applications. In particular, these membranes provide a promising, inexpensive platform for chlorine degradation and fouling-resistant membranes for water purification that can be produced on an industrial scale.

  16. Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Yuzo; Ueki, Takeshi; McIntosh, Lucas D.; Tamura, Saki; Niitsuma, Kazuyuki; Imaizumi, Satoru; Lodge, Timothy P.; Watanabe, Masayoshi (U of Tokyo); (UMM); (Yokohama)

    2016-04-29

    Here we investigate a hierarchical morphology change and accompanying sol–gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol–gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. For each phase was formed reversibly and rapidly over the corresponding temperature range. Finally, the jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).

  17. Effect of block length on the self-assembly of end-capping perfluoroalkyl moieties on the polymer surface

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Most research on copolymers with fluorinated monomers has focused on the relationship between fluorinated monomer content and the corresponding surface structure. However,the influence of the non-fluorinated block on the surface structure of the copolymer film is unknown. Various molecular weight poly(butyl methacrylates) (PBMA) end-capped with 2-perfluorooctylethyl methacrylate (FMA) units (PBMA-ec-FMA) have been synthesized by atom transfer radical polymerization (ATRP). The effect of the PBMA block length on the surface structure and properties of the polymers both in the solid state and in solution was investigated using various techniques. X-ray photoelectron spectroscopy (XPS),sum frequency generation (SFG) vibrational spectroscopy and X-ray diffraction (XRD) analyses indicated that longer PBMA blocks enhanced both the enrichment of the fluorinated moieties and the order of the packing orientation of the perfluoroalkyl side chains on the surface. This enhancement was attributed mainly to the molecular aggregate structure of the end-capped polymers with long PBMA blocks in the solution and to the interfacial structure at the air/liquid interface,which favors the -(CF2)7CF3 moieties self-assembling on the polymer surface during film formation. This observation suggests that the polyacrylate block structure in fluorinated diblock copolymers,in addition to the fluorinated monomer content,plays an important role in structure formation on the solid surface.

  18. Polymer-facilitated low temperature fusing of spray-coated silver nanowire networks as transparent top and bottom electrodes in small molecule organic photovoltaics (Presentation Recording)

    Science.gov (United States)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-10-01

    Networks of silver nanowires (AgNWs) are promising candidates for transparent conducting electrodes in organic photovoltaics (OPV), as they achieve similar performance as the commonly used indium tin oxide (ITO) at lower cost and increased flexibility. The initial sheet resistance (Rs) of AgNW electrodes typically needs to be reduced by a post-annealing step (90 min@200 °C), being detrimental for processing on polymeric substrates. We present novel low temperature-based methods to integrate AgNWs in organic small molecule-based photovoltaics, either as transparent and highly conductive bottom-electrode or, for the first time, as spray-coated AgNW top-electrode. The bottom-electrodes are prepared by organic matrix assisted low-temperature fusing. Here, selected polymers are coated below the AgNWs to increase the interaction between NWs and substrate. In comparison to networks without these polymeric sublayers, the Rs is reduced by two orders of magnitude. AgNW top-electrodes are realized by dispersing modified high-quality AgNWs in inert solvents, which do not damage small molecule layers. Accordingly, our AgNW dispersion can be spray-coated onto all kind of OPV devices. Both bottom- and top-electrodes show a Rs of 87 % transparency directly after spray-coating at very low substrate temperatures of <80 °C. We also demonstrate the implementation of our AgNW electrodes in organic solar cells. The corresponding devices show almost identical performance compared to organic solar cells exploiting ITO as bottom or thermally evaporated thin-metal as top-electrode.

  19. Self-assembly of silk-elastinlike protein polymers into three-dimensional scaffolds for biomedical applications

    Science.gov (United States)

    Zeng, Like

    Production of brand new protein-based materials with precise control over the amino acid sequences at single residue level has been made possible by genetic engineering, through which artificial genes can be developed that encode protein-based materials with desired features. As an example, silk-elastinlike protein polymers (SELPs), composed of tandem repeats of amino acid sequence motifs from Bombyx mori (silkworm) silk and mammalian elastin, have been produced in this approach. SELPs have been studied extensively in the past two decades, however, the fundamental mechanism governing the self-assembly process to date still remains largely unresolved. Further, regardless of the unprecedented success when exploited in areas including drug delivery, gene therapy, and tissue augmentation, SELPs scaffolds as a three-dimensional cell culture model system are complicated by the inability of SELPs to provide the embedded tissue cells with appropriate biochemical stimuli essential for cell survival and function. In this dissertation, it is reported that the self-assembly of silk-elastinlike protein polymers (SELPs) into nanofibers in aqueous solutions can be modulated by tuning the curing temperature, the size of the silk blocks, and the charge of the elastin blocks. A core-sheath model was proposed for nanofiber formation, with the silk blocks in the cores and the hydrated elastin blocks in the sheaths. The folding of the silk blocks into stable cores -- affected by the size of the silk blocks and the charge of the elastin blocks -- plays a critical role in the assembly of silk-elastin nanofibers. The assembled nanofibers further form nanofiber clusters on the microscale, and the nanofiber clusters then coalesce into nanofiber micro-assemblies, interconnection of which eventually leads to the formation of three-dimensional scaffolds with distinct nanoscale and microscale features. SELP-Collagen hybrid scaffolds were also fabricated to enable independent control over the

  20. Fabrication and characterization of Ag/polymer nanocomposite films through layer-by-layer self-assembly technique

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaohong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Science, Beijing 100039 (China); Wang Jinqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang Junyan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: junyanzh@yahoo.com; Liu Bin; Zhou Jinfang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Science, Beijing 100039 (China); Yang Shengrong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: sryang@lzb.ac.cn

    2007-07-31

    Multilayer nanocomposite films composed of negative charged Ag nanosized particles and cationic polyallylamine hydrochloride (PAH) molecules were fabricated on polymer modified single-crystal silicon and flat glass slides by a layer-by-layer (LBL) molecular self-assembly technique. The X-ray photoelectron spectroscopy analysis showed that the formed Ag particles successfully absorbed onto the positively charged surfaces. The atomic force microscopy image of a two-cycle Ag/PAH bilayer film showed that no surface damage or defects existed on the thin-films surface. The Ag particles were densely and homogeneously distributed on the surface and relatively uniform in size. Goniometry was employed to verify the assembly process and the water contact angles oscillated regularly, depending on the composition of the outermost layer. By using the LBL deposition technique, a molecular-level ordered multilayer film with the thickness up to 40 layers (20 bilayers) was obtained. Results from UV-vis spectroscopy and ellipsometry measurements revealed that the self-assembly of the Ag/PAH multilayer film was well quantitative and reproducible. Thus we can conclude that the consecutive LBL deposition technique is a feasible and effective way to produce multilayer film and control the surface properties.

  1. Fabrication and characterization of Ag/polymer nanocomposite films through layer-by-layer self-assembly technique

    International Nuclear Information System (INIS)

    Multilayer nanocomposite films composed of negative charged Ag nanosized particles and cationic polyallylamine hydrochloride (PAH) molecules were fabricated on polymer modified single-crystal silicon and flat glass slides by a layer-by-layer (LBL) molecular self-assembly technique. The X-ray photoelectron spectroscopy analysis showed that the formed Ag particles successfully absorbed onto the positively charged surfaces. The atomic force microscopy image of a two-cycle Ag/PAH bilayer film showed that no surface damage or defects existed on the thin-films surface. The Ag particles were densely and homogeneously distributed on the surface and relatively uniform in size. Goniometry was employed to verify the assembly process and the water contact angles oscillated regularly, depending on the composition of the outermost layer. By using the LBL deposition technique, a molecular-level ordered multilayer film with the thickness up to 40 layers (20 bilayers) was obtained. Results from UV-vis spectroscopy and ellipsometry measurements revealed that the self-assembly of the Ag/PAH multilayer film was well quantitative and reproducible. Thus we can conclude that the consecutive LBL deposition technique is a feasible and effective way to produce multilayer film and control the surface properties

  2. Steric hindrance regulated supramolecular assembly between β-cyclodextrin polymer and pyrene for alkaline phosphatase fluorescent sensing

    Science.gov (United States)

    Song, Chunxia; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Jianbo; Huang, Jin; Zhou, Maogui; Guo, Xiaochen

    2016-03-01

    We herein report a strategy for sensitive alkaline phosphatase (ALP) fluorescent sensing based on steric hindrance regulated supramolecular assembly between β-cyclodextrin polymer (polyβ-CD) and pyrene. The fluorescence of pyrene was enhanced more than 10 times through supramolecular assembly with polyβ-CD. The 5‧-phosphorylated dsDNA probe with pyrene attached on the 3‧-terminal could be cleaved by λ exonuclease (λ exo), yielding pyrene attached on mononucleotides. Pyrene attached on mononucleotides could easily enter the cavity of polyβ-CD, resulting in fluorescence enhancement. When ALP was introduced, it could remove 5‧-phosphate groups from dsDNA and then prevented the cleavage of dsDNA. Pyrene attached on dsDNA was difficult to enter the cavity of polyβ-CD because of steric hindrance, resulting in an inconspicuous fluorescence enhancement. Owing to the excellent fluorescence enhancement during steric hindrance regulated supramolecular assembly, excellent performance of the assay method was achieved for ALP with a detection limit of 0.04 U mL- 1. The detection limit was superior or comparable with the reported methods. Besides, this method was simple in design, avoiding double-labeling of probe.

  3. Synthesis of silver nanowires using hydrothermal technique for flexible transparent electrode application

    Science.gov (United States)

    Vijila, C. V. Mary; Rahman, K. K. Arsina; Parvathy, N. S.; Jayaraj, M. K.

    2016-05-01

    Transparent conducting films are becoming increasingly interesting because of their applications in electronics industry such as their use in solar energy applications. In this work silver nanowires were synthesized using solvothermal method by reducing silver nitrate and adding sodium chloride for assembling silver into nanowires. Absorption spectra of nanowires in the form of a dispersion in deionized water, AFM and SEM images confirm the nanowire formation. Solution of nanowire was coated over PET films to obtain transparent conducting films.

  4. Hairy nanoparticle assemblies as one-component functional polymer nanocomposites: opportunities and challenges

    KAUST Repository

    Fernandes, Nikhil J.

    2013-03-01

    Over the past three decades, the combination of inorganic-nanoparticles and organic-polymers has led to a wide variety of advanced materials, including polymer nanocomposites (PNCs). Recently, synthetic innovations for attaching polymers to nanoparticles to create hairy nanoparticles (HNPs) has expanded opportunities in this field. In addition to nanoparticle compatibilization for traditional particle-matrix blending, neat-HNPs afford one-component hybrids, both in composition and properties, which avoids issues of mixing that plague traditional PNCs. Continuous improvements in purity, scalability, and theoretical foundations of structure-performance relationships are critical to achieving design control of neat-HNPs necessary for future applications, ranging from optical, energy, and sensor devices to lubricants, green-bodies, and structures. © 2013 Materials Research Society.

  5. An anisotropic snowflake-like structural assembly of polymer-capped gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Parab, Harshala; Jung, Cheulhee; Woo, Min-Ah; Park, Hyun Gyu, E-mail: hgpark@kaist.ac.kr [Korea Advanced Institute of Science and Technology, Department of Chemical and Biomolecular Engineering (Korea, Republic of)

    2011-05-15

    Snowflake-like structural assembly of isotropic gold nanoparticles (GNPs) is reported. A modified polyamine method has been employed to synthesize positively charged GNPs in presence of a polymeric metaphosphate. This process yields fascinating dendritic self-assembled morphologies. Structural characterization revealed that there was aggregation of crystalline GNPs. The aggregates of GNPs formed in the initial stage of synthesis are assumed to act as the bulging seeds for final growth of complex morphologies at nanometer to micrometer length scale. Self-assembly of GNPs was found to be greatly influenced by the concentration of gold precursor. Diffusion limited aggregation of GNPs is suggested as the plausible mechanism for this nanoparticle self-organization process.

  6. Self-Assembled Nanocomposite Organic Polymers with Aluminum and Scandium as Heterogeneous Water-Compatible Lewis Acid Catalysts.

    Science.gov (United States)

    Miyamura, Hiroyuki; Sonoyama, Arisa; Hayrapetyan, Davit; Kobayashi, Shū

    2015-09-01

    While water-compatible Lewis acids have great potential as accessible and environmentally benign catalysts for various organic transformations, efficient immobilization of such Lewis acids while keeping high activity and without leaching of metals even under aqueous conditions is a challenging task. Self-assembled nanocomposite catalysts of organic polymers, carbon black, aluminum reductants, and scandium salts as heterogeneous water-compatible Lewis acid catalysts are described. These catalysts could be successfully applied to various C-C bond-forming reactions without leaching of metals. Scanning transmission electron microscopy analyses revealed that the nanocomposite structure of Al and Sc was fabricated in these heterogeneous catalysts. It is noted that Al species, which are usually decomposed rapidly in the presence of water, are stabilized under aqueous conditions. PMID:26228075

  7. Cooperative Self-Assembly Transfer from Hierarchical Supramolecular Polymers to Gold Nanoparticles.

    Science.gov (United States)

    Coelho, João Paulo; Tardajos, Gloria; Stepanenko, Vladimir; Rödle, Alexander; Fernández, Gustavo; Guerrero-Martínez, Andrés

    2015-11-24

    The transfer of information encoded by molecular subcomponents is a key phenomenon that regulates the biological inheritance in living organisms, yet there is a lack of understanding of related transfer mechanisms at the supramolecular level in artificial multicomponent systems. Our contribution to tackle this challenge has focused on the design of a thiolated π-conjugated linking unit, whose hierarchical, cooperative self-assembly in nonpolar media can be efficiently transferred from the molecular to the nanoscopic level, thereby enabling the reversible self-assembly of gold nanoparticle (AuNP) clusters. The transfer of supramolecular information by the linking π-system can only take place when a specific cooperative nucleation-elongation mechanism is operative, whereas low-ordered noncooperative assemblies formed below a critical concentration do not suffice to extend the order to the AuNP level. To the best of our knowledge, our approach has allowed for the first time a deep analysis of the hierarchy levels and thermodynamics involved in the self-assembly of AuNPs.

  8. Block copolymer assembly on nanoscale patterns of polymer brushes formed by electrohydrodynamic jet printing.

    Science.gov (United States)

    Onses, M Serdar; Ramírez-Hernández, Abelardo; Hur, Su-Mi; Sutanto, Erick; Williamson, Lance; Alleyne, Andrew G; Nealey, Paul F; de Pablo, Juan J; Rogers, John A

    2014-07-22

    Fundamental understanding of the self-assembly of domains in block copolymers (BCPs) and capabilities in control of these processes are important for their use as nanoscale templates in various applications. This paper focuses on the self-assembly of spin-cast and printed poly(styrene-block-methyl methacrylate) BCPs on patterned surface wetting layers formed by electrohydrodynamic jet printing of random copolymer brushes. Here, end-grafted brushes that present groups of styrene and methyl methacrylate in geometries with nanoscale resolution deterministically define the morphologies of BCP nanostructures. The materials and methods can also be integrated with lithographically defined templates for directed self-assembly of BCPs at multiple length scales. The results provide not only engineering routes to controlled formation of complex patterns but also vehicles for experimental and simulation studies of the effects of chemical transitions on the processes of self-assembly. In particular, we show that the methodology developed here provides the means to explore exotic phenomena displayed by the wetting behavior of BCPs, where 3-D soft confinement, chain elasticity, interfacial energies, and substrate's surface energy cooperate to yield nonclassical wetting behavior. PMID:24882265

  9. Conductive polymer nanocomposites with hierarchical multi-scale structures via self-assembly of carbon-nanotubes on graphene on polymer-microspheres

    Science.gov (United States)

    Tang, Changyu; Long, Gucheng; Hu, Xin; Wong, Ka-Wai; Lau, Woon-Ming; Fan, Meikun; Mei, Jun; Xu, Tao; Wang, Bin; Hui, David

    2014-06-01

    A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO-stabilized CNTs for the formation of an intriguing 3D hierarchical multi-scale structure. During this process, GO is reduced to conductive reduced-graphene oxide (RGO). The resultant RGO sheets act as ``nano-walls'' to prevent CNTs from randomly diffusing into the polymer bulk during thermal pressing of RGO-CNT/microspheres, which results in the formation of a 3D foam-like network of RGO-CNTs with high quality. The resultant composite with such a structure gives an ultra-low percolation threshold (0.03 vol% RGO-CNTs) and a reasonably high conductivity (153 S m-1 at 4 vol% RGO-CNTs), which could satisfy various applications requiring both transparency and electrical conduction characteristics (e.g. transparent antistatic coatings, capacitive touch-screens, and transparent electronic devices).A novel and highly conductive 3-dimensional (3D) hierarchical multi-scale structure is formed by a new, simple, facile, and water-based method that enables practical production of conductive carbon nanofiller/polymer composites. More specifically, the π-π interaction between CNTs and graphene oxide (GO) is exploited to disperse conductive but non-polar CNTs with amphiphilic GO sheets to form a stable aqueous colloidal solution. Aqueous-dispersible latex-polystyrene microspheres are then added to enable the self-assembly processes of anchoring CNTs on GO and wrapping microspheres with GO

  10. Miktoarms hyperbranched polymer brushes:One-step fast synthesis by parallel click chemistry and hierarchical self-assembly

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (~100%),very fast (~ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.

  11. Fabrication of self-assembled monolayers (SAMs) and inorganic micropattern on flexible polymer substrate.

    Science.gov (United States)

    Xiang, Junhui; Zhu, Peixin; Masuda, Yoshitake; Koumoto, Kunihito

    2004-04-13

    By grafting (aminopropyl)triethoxysilane (APTES) as the buffer layer on poly(ethylene terephthalate) (PET) surface, the SAMs ofoctadecyltrichlorosilane (OTS), phenyltrichlorosilane (PTCS), vinyltrichlorosilane (VTCS), andp-tolyltrichlorosilane (TTCS) were fabricated on the flexible polymer substrate. The properties of SAMs were accurately controlled by adjusting the immersing time of substrates in the solutions and the concentration of the solutions. The SAMs acted as templates, and TiO2 micropattern was successfully deposited on OTS, TTCS, and PTCS SAMs. PMID:15875858

  12. Polymer complexes. LVIII. Structures of supramolecular assemblies of vanadium with chelating groups

    Science.gov (United States)

    El-Sonbati, A. Z.; Belal, A. A. M.; Diab, M. A.; Balboula, M. Z.

    2011-03-01

    Oxovanadium(IV) polymer complexes of formulation {[(VO)L] 2} n (1) and [(VO)LB] n (2-4), where H 2L is tridentate and dianionic ligand (allylazorhodanine) and B is planar heterocyclic and aliphatic base have been prepared and characterized by elemental analyses, IR, 1H NMR, electronic spin resonance spectra, magnetic susceptibility measurements, molar conductance and thermal studies. The molecular structure shows the presence of a vanadyl group in six-coordinate VNO 3/VN 3O 3 coordination geometry. The N,N-donor heterocyclic and aliphatic bas displays a chelating mode of binding with an N-donor site trans to the vanadyl oxo-group. In all polymeric complexes (1-4) the ligand coordinates through oxygen of phenolic/enolic and azodye nitrogen. The molar conductivity data show them to be non-electrolytes. All the polymer complexes are ESR active due to the presence of an unpaired electron. The calculated bonding parameters indicate that in-plane σ bonding is more covalent than in-plane π bonding. From the electronic, magnetic and ESR spectral data suggest that all the oxovanadium(IV) polymer complexes have distorted octahedral geometry. The thermal decomposition process of the polymeric complexes involves three decomposition steps.

  13. Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells

    International Nuclear Information System (INIS)

    This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

  14. Effect of Small Molecule Osmolytes on the Self-Assembly and Functionality of Globular Protein-Polymer Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Carla S.; Xu, Liza; Olsen, Bradley D. [MIT

    2013-12-05

    Blending the small molecule osmolytes glycerol and trehalose with the model globular protein–polymer block copolymer mCherry-b-poly(N-isopropyl acrylamide) (mCherry-b-PNIPAM) is demonstrated to improve protein functionality in self-assembled nanostructures. The incorporation of either additive into block copolymers results in functionality retention in the solid state of 80 and 100% for PNIPAM volume fractions of 40 and 55%, respectively. This represents a large improvement over the 50–60% functionality observed in the absence of any additive. Furthermore, glycerol decreases the thermal stability of block copolymer films by 15–20 °C, while trehalose results in an improvement in the thermal stability by 15–20 °C. These results suggest that hydrogen bond replacement is responsible for the retention of protein function but suppression or enhancement of thermal motion based on the glass transition of the osmolyte primarily determines thermal stability. While both osmolytes are observed to have a disordering effect on the nanostructure morphology with increasing concentration, this effect is less pronounced in materials with a larger polymer volume fraction. Glycerol preferentially localizes in the protein domains and swells the nanostructures, inducing disordering or a change in morphology depending on the PNIPAM coil fraction. In contrast, trehalose is observed to macrophase separate from the block copolymer, which results in nanodomains becoming more disordered without changing significantly in size.

  15. Conducting Polymer Nanostructures and Nanocomposites with Carbon Nanotubes: Hierarchical Assembly by Molecular Electrochemistry, Growth Aspects and Property Characterization.

    Science.gov (United States)

    Gupta, Sanju; Price, Carson; Heintzman, Eli

    2016-01-01

    Conducting (or π-conjugated) polymers are promising materials for preparing supramolecular nano-structures and nanocomposites. We report controlled nanostructure syntheses of polypyrrole (PPy) and poylaniline (PANi) via electropolymerization (i.e., in-situ electrochemical anodic oxidation). The density, shape, caliber and thickness of self-assembled PPy micro-containers are regulated by electrochemical potential window for H2 bubbles and number of cyclic voltammetric (potentiodynamic) scans. Likewise, we employed amperometry, chronopotentiometry and potentiodynamic modes using hydrochloric acid as oxidizing agent to prepare PANi nanoparticles and nanotubules. We present our findings from the viewpoint of molecular electrochemistry with growth kinetic aspects yielding mechanistic details (initially forming dimers and oligomers as nucleating agents followed by polymer growth). Also targeted is forming nanocomposites with functionalized single- and multi-walled carbon nanotubes (FSWCNTs and FMWCNTs) as reinforced agent to optimize structural and functional properties. All of these novel nanomaterials are characterized using a range of complementary techniques to establish microscopic structure-property-function relationship. PMID:27398466

  16. Self-assembled tin-doped ZnO nanowire and nanoplate structures grown by thermal treatment of ZnS powder

    Science.gov (United States)

    Ortega, Y.; Fernández, P.; Piqueras, J.

    2009-05-01

    Sintering of a ZnS-SnO 2 mixture under argon flow leads to the growth of columnar nanoplate arrays as well as arrays of nanowires, nanorods and nanoplates with six-fold symmetry. The six-fold nanoplate structures correspond to a more advanced stage of growth than the nanowire structures. Cathodoluminescence (CL) in the scanning electron microscope (SEM) shows that the structures contain Sn, but the amount of this element is normally under the detection limit of X-ray energy-dispersive spectroscopy (EDS). The formation of branches in the hierarchical structures depends on the presence of Sn and on defects in the mixture powder.

  17. Nanowire photonics

    Directory of Open Access Journals (Sweden)

    Peter J. Pauzauskie

    2006-10-01

    Full Text Available The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. However, several challenges remain before the potential of nanowire building blocks is fully realized. We cover recent advances in nanowire synthesis, characterization, lasing, integration, and the eventual application to relevant technical and scientific questions.

  18. Morphology control of polymer: Fullerene solar cells by nanoparticle self-assembly

    Science.gov (United States)

    Zhang, Wenluan

    During the past two decades, research in the field of polymer based solar cells has attracted great effort due to their simple processing, mechanical flexibility and potential low cost. A standard polymer solar cell is based on the concept of a bulk-heterojunction composed of a conducting polymer as the electron donor and a fullerene derivative as the electron acceptor. Since the exciton lifetime is limited, this places extra emphasis on control of the morphology to obtain improved device performance. In this thesis, detailed characterization and novel morphological design of polymer solar cells was studied, in addition, preliminary efforts to transfer laboratory scale methods to industrialized device fabrication was made. Magnetic contrast neutron reflectivity was used to study the vertical concentration distribution of fullerene nanoparticles within poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b]thiophene (pBTTT) thin film. Due to the wide space between the side chains of polymer, these fullerene nanoparticles intercalate between them creating a stable co-crystal structure. Therefore, a high volume fraction of fullerene was needed to obtain optimal device performance as phase separated conductive pathways are required and resulted in a homogeneous fullerene concentration profile through the film. Small angle neutron scattering was used to find there is amorphous fullerene even at lower concentration since it was previously believed that all fullerene formed a co-crystal. These fullerene molecules evolve into approximately 15 nm sized agglomerates at higher concentrations to improve electron transport. Unfortunately, thermal annealing gives these agglomerates mobility to form micrometer sized crystals and reduce the device performance. In standard poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCMBM) solar cells, a higher concentration of PCBM at the cathode interface is desired due to the band alignment structure. This was

  19. Responsive supramolecular polymer metallogel constructed by orthogonal coordination-driven self-assembly and host/guest interactions.

    Science.gov (United States)

    Yan, Xuzhou; Cook, Timothy R; Pollock, J Bryant; Wei, Peifa; Zhang, Yanyan; Yu, Yihua; Huang, Feihe; Stang, Peter J

    2014-03-26

    An emerging strategy for the fabrication of advanced supramolecular materials is the use of hierarchical self-assembly techniques wherein multiple orthogonal interactions between molecular precursors can produce new species with attractive properties. Herein, we unify the spontaneous formation of metal-ligand bonds with the host/guest chemistry of crown ethers to deliver a 3D supramolecular polymer network (SPN). Specifically, we have prepared a highly directional dipyridyl donor decorated with a benzo-21-crown-7 moiety that undergoes coordination-driven self-assembly with a complementary organoplatinum acceptor to furnish hexagonal metallacycles. These hexagons subsequently polymerize into a supramolecular network upon the addition of a bisammonium salt due to the formation of [2]pseudorotaxane linkages between the crown ether and ammonium moieties. At high concentrations, the resulting 3D SPN becomes a gel comprising many cross-linked metallohexagons. Notably, thermo- and cation-induced gel-sol transitions are found to be completely reversible, reflecting the dynamic and tunable nature of such supramolecular materials. As such, these results demonstrate the structural complexity that can be obtained when carefully controlling multiple interactions in a hierarchical fashion, in this case coordination and host/guest chemistry, and the interesting dynamic properties associated with the materials thus obtained.

  20. Hierarchical self-assembly of telechelic star polymers: from soft patchy particles to gels and diamond crystals

    Science.gov (United States)

    Capone, Barbara; Coluzza, Ivan; Blaak, Ronald; Lo Verso, Federica; Likos, Christos N.

    2013-09-01

    The design of self-assembling materials in the nanometer scale focuses on the fabrication of a class of organic and inorganic subcomponents that can be reliably produced on a large scale and tailored according to their vast applications for, e.g. electronics, therapeutic vectors and diagnostic imaging agent carriers, or photonics. In a recent publication (Capone et al 2012 Phys. Rev. Lett. 109 238301), diblock copolymer stars have been shown to be a novel system, which is able to hierarchically self-assemble first into soft patchy particles and thereafter into more complex structures, such as the diamond and cubic crystal. The self-aggregating single star patchy behavior is preserved from extremely low up to high densities. Its main control parameters are related to the architecture of the building blocks, which are the number of arms (functionality) and the fraction of attractive end-monomers. By employing a variety of computational and theoretical tools, ranging from the microscopic to the mesoscopic, coarse-grained level in a systematic fashion, we investigate the crossover between the formation of microstructure versus macroscopic phase separation, as well as the formation of gels and networks in these systems. We finally show that telechelic star polymers can be used as building blocks for the fabrication of open crystal structures, such as the diamond or the simple-cubic lattice, taking advantage of the strong correlation between single-particle patchiness and lattice coordination at finite densities.

  1. Multi-shape memory polymers achieved by the spatio-assembly of 3D printable thermoplastic building blocks.

    Science.gov (United States)

    Li, Hongze; Gao, Xiang; Luo, Yingwu

    2016-04-01

    Multi-shape memory polymers were prepared by the macroscale spatio-assembly of building blocks in this work. The building blocks were methyl acrylate-co-styrene (MA-co-St) copolymers, which have the St-block-(St-random-MA)-block-St tri-block chain sequence. This design ensures that their transition temperatures can be adjusted over a wide range by varying the composition of the middle block. The two St blocks at the chain ends can generate a crosslink network in the final device to achieve strong bonding force between building blocks and the shape memory capacity. Due to their thermoplastic properties, 3D printing was employed for the spatio-assembly to build devices. This method is capable of introducing many transition phases into one device and preparing complicated shapes via 3D printing. The device can perform a complex action via a series of shape changes. Besides, this method can avoid the difficult programing of a series of temporary shapes. The control of intermediate temporary shapes was realized via programing the shapes and locations of building blocks in the final device.

  2. Towards a comprehensive insight into efficient hydrogen production by self-assembled Ru(bpy)3(2+)-polymer-Pt artificial photosystems.

    Science.gov (United States)

    Lin, Huan; Liu, Dan; Long, Jinlin; Zhang, Zizhong; Zhuang, Huaqiang; Zheng, Yi; Wang, Xuxu

    2015-04-28

    The role of polymers in artificial photosystems has been studied in detail. The photosystems were composed of tris(2,2'-bipyridyl) ruthenium(II) chloride as a photosensitizer (PS), colloidal Pt stabilized by polymer as a hydrogen-evolving catalyst and sodium ascorbate as an electron donor, without the addition of a traditional molecular electron mediator. Comprehensive insights into the production of hydrogen on irradiation with visible light were achieved. Several polymers, including neutral polyvinyl pyrrolidone, anionic poly(sodium 4-styrene sulfonate) and poly(acrylic acid) not only stabilized the nanoparticles, but were also effective in the production of hydrogen. Under the optimum conditions, an outstanding apparent quantum efficiency of 12.8% for the evolution of hydrogen was achieved. The formation of self-assembled and spatially separated donor-acceptor complexes via the non-covalent intermolecular interaction between PS and the polymer-Pt was pivotal in the efficient conversion of solar energy to hydrogen fuel. Important details of the photo-induced electron and energy transfer processes in the self-assembled artificial photosystems were determined by nanosecond transient absorption spectrometry and time-resolved fluorescence spectrometry. The initial step in the photo-catalytic production of hydrogen was a reductive quenching of the triplet excited state of the PS by sodium ascorbate, leading to a reduced form of PS, which could then be quickly quenched by the polymer. The rate-determining step was the electron transfer from PS to the catalyst via the polymer bridge. PMID:25811660

  3. Interfacial Assembly of Protein-polymer Nano-conjugates into Stimulus-Responsive Biomimetic Protocells

    OpenAIRE

    Huang, Xin; Li, Mei; Green, David C.; Williams, David S.; Patil, Avinash J.; Mann, Stephen.

    2013-01-01

    The mechanism of spontaneous assembly of microscale compartments is a central question for the origin of life, and has technological repercussions in diverse areas such as materials science, catalysis, biotechnology and biomedicine. Such compartments need to be semi-permeable, structurally robust and capable of housing assemblages of functional components for internalized chemical transformations. In principle, proteins should be ideal building blocks for the construction of membrane-bound co...

  4. Collagen-like peptides and peptide-polymer conjugates in the design of assembled materials

    OpenAIRE

    Luo, Tianzhi; Kiick, Kristi L.

    2013-01-01

    Collagen is the most abundant protein in mammals, and there has been long-standing interest in understanding and controlling collagen assembly in the design of new materials. Collagen-like peptides (CLP), also known as collagen-mimetic peptides (CMP) or collagen-related peptides (CRP), have thus been widely used to elucidate collagen triple helix structure as well as to produce higher-order structures that mimic natural collagen fibers. This mini-review provides an overview of recent progress...

  5. A Robust Highly Aligned DNA Nanowire Array-Enabled Lithography for Graphene Nanoribbon Transistors.

    Science.gov (United States)

    Kang, Seok Hee; Hwang, Wan Sik; Lin, Zhiqun; Kwon, Se Hun; Hong, Suck Won

    2015-12-01

    Because of its excellent charge carrier mobility at the Dirac point, graphene possesses exceptional properties for high-performance devices. Of particular interest is the potential use of graphene nanoribbons or graphene nanomesh for field-effect transistors. Herein, highly aligned DNA nanowire arrays were crafted by flow-assisted self-assembly of a drop of DNA aqueous solution on a flat polymer substrate. Subsequently, they were exploited as "ink" and transfer-printed on chemical vapor deposited (CVD)-grown graphene substrate. The oriented DNA nanowires served as the lithographic resist for selective removal of graphene, forming highly aligned graphene nanoribbons. Intriguingly, these graphene nanoribbons can be readily produced over a large area (i.e., millimeter scale) with a high degree of feature-size controllability and a low level of defects, rendering the fabrication of flexible two terminal devices and field-effect transistors.

  6. Enhanced performance of polymer solar cells with a monolayer of assembled gold nanoparticle films fabricated by Langmuir-Blodgett technique

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaoqiang; Yang, Xi; Fu, Weifei; Xu, Mingsheng [State Key Lab of Silicon Materials, MOE Key Laboratory of Macromolecular Synthesis and Functionalization, and Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chen, Hongzheng, E-mail: hzchen@zju.edu.cn [State Key Lab of Silicon Materials, MOE Key Laboratory of Macromolecular Synthesis and Functionalization, and Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Au NP monolayers are incorporated into ITO/anodic buffer layer by LB method. Black-Right-Pointing-Pointer Au NP monolayers are surface oxidized by UV/O{sub 3} treatment. Black-Right-Pointing-Pointer The effects of packing density and particle size on device performance were investigated. Black-Right-Pointing-Pointer Both short-circuit current and open-circuit voltage are improved with Au NP layer. - Abstract: We reported the enhanced performance of polymer solar cells with the blend of poly (2-methoxy-5(2 Prime -ethylhexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as active layer by incorporation of an assembled gold nanoparticle (Au NP) monolayer. The dense Au NP monolayer has been fabricated by Langmuir-Blodgett (LB) assembly and positioned between the transparent electrode ITO and the anode-modification PEDOT:PSS [poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate)] layer, resulting in the device architecture of ITO/Au/PEDOT:PSS/MEH-PPV:PCBM/Al. We attribute the performance improvement to the localized surface plasmon resonance (LSPR) effect of Au NP films, which could lead to the increased absorption of the active layer. The parameters (nanoparticle size and interparticle distance) that govern this SPR effect have been optimized by selecting various sizes of Au NPs and controlling the LB assembly conditions. We observed {approx}10-20% enhancement in power conversion efficiency for all the devices with the Au NP monolayer.

  7. Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, Frank; Schiek, Manuela; Al-Shamery, Katharina;

    Single crystalline nanowires from fluorescing organic molecules like para-phenylenes or thiophenes are supposed to become key elements in future integrated optoelectronic devices [1]. For a sophisticated design of devices based on nanowires the basic principles of the nanowire formation have...... to be well understood [2]. Nanowires from para-phenylenes, from ®-thiophenes, and from phenylene/thiophene co-oligomers, Fig. 1, are investigated exemplarily. Epitaxy and electrostatic interactions determine the microscopic growth mechanism, whereas kinetics ascertains the macroscopic habit. Results from...... atomic force microscopy and from polarized far-field optical microscopy for various prototypical molecules are reproduced by electrostatic and Monte Carlo calculations. Based on the crystal structure, predictions on the growth habit from other conjugated molecules become in reach....

  8. High-field mobility in an assembly of conjugated polymer segments

    Science.gov (United States)

    Bussac, M. N.; Zuppiroli, L.

    1996-08-01

    We present a calculation of the hopping rate between the finite chains of a conjugated polymer. It is based on the optimization of the semiclassical hopping rates with respect to the possible widths and possible positions of the large polaron during the jump. For sufficient long chains and high enough fields, we arrive at an expression for the mobility which resembles a Fowler-Nordheim dependence with the field F, namely, exp-(F0/F). In this regime the mobility is weakly temperature dependent.

  9. Interplay between polymer chain conformation and nanoparticle assembly in model industrial silica/rubber nanocomposites.

    Science.gov (United States)

    Bouty, Adrien; Petitjean, Laurent; Chatard, Julien; Matmour, Rachid; Degrandcourt, Christophe; Schweins, Ralf; Meneau, Florian; Kwasńiewski, Paweł; Boué, François; Couty, Marc; Jestin, Jacques

    2016-01-01

    The question of the influence of nanoparticles (NPs) on chain dimensions in polymer nanocomposites (PNCs) has been treated mainly through the fundamental way using theoretical or simulation tools and experiments on well-defined model PNCs. Here we present the first experimental study on the influence of NPs on the polymer chain conformation for PNCs designed to be as close as possible to industrial systems employed in the tire industry. PNCs are silica nanoparticles dispersed in a styrene-butadiene-rubber (SBR) matrix whose NP dispersion can be managed by NP loading with interfacial coatings or coupling additives usually employed in the manufacturing mixing process. We associated specific chain (d) labeling, and the so-called zero average contrast (ZAC) method, with SANS, in situ SANS and SAXS/TEM experiments to extract the polymer chain scattering signal at rest for non-cross linked and under stretching for cross-linked PNCs. NP loading, individual clusters or connected networks, as well as the influence of the type, the quantity of interfacial agent and the influence of the elongation rate have been evaluated on the chain conformation and on its related deformation. We clearly distinguish the situations where the silica is perfectly matched from those with unperfected matching by direct comparison of SANS and SAXS structure factors. Whatever the silica matching situation, the additive type and quantity and the filler content, there is no significant change in the polymer dimension for NP loading up to 15% v/v within a range of 5%. One can see an extra scattering contribution at low Q, as often encountered, enhanced for non-perfect silica matching but also visible for perfect filler matching. This contribution can be qualitatively attributed to specific h or d chain adsorption on the NP surface inside the NP cluster that modifies the average scattering neutron contrast of the silica cluster. Under elongation, NPs act as additional cross-linking junctions

  10. Template-free fabrication of Ag nanowire arrays/Al2O3 assembly with flexible collective longitudinal-mode resonance and ultrafast nonlinear optical response

    Science.gov (United States)

    Hui, Shuai; Gao, Junhua; Wu, Xingzhi; Li, Zhongguo; Zou, Yousheng; Song, Yinglin; Cao, Hongtao

    2016-06-01

    We utilized a co-sputtering technique without any templates, featuring growing and etching synchronously, to delicately fabricate dense and ultrafine Ag nanowire arrays/alumina matrix composite films. Both the diameter and separation distance of the Ag nanowire arrays in the composites are not only within the scope of sub-10 nm but also tunable, which is very hard to accomplish for the conventional optical lithography- or template-based method. It is exhibited that the collective longitudinal plasmon resonance of the composite films, covering a wide range from visible to the near infrared region, is extremely sensitive to the geometrical parameters of the Ag nanowires, owing to the strong plasmonic coupling among neighboring nanowires. The experimental observations were also theoretically supported by the near-field electromagnetic numerical simulation. More interestingly, the fabricated composite films demonstrated ultrafast nonlinear optical response in the visible light region under femtosecond laser excitation, possessing a short relaxation time of 1.45 ps for the longitudinal mode (L mode) resonance. These results indicate that the proposed composite films as a building block with exotic optical properties could provide an opportunity to construct integrated nanodevices for plasmonic optical applications.

  11. Nanowire Lasers

    Directory of Open Access Journals (Sweden)

    Couteau C.

    2015-05-01

    Full Text Available We review principles and trends in the use of semiconductor nanowires as gain media for stimulated emission and lasing. Semiconductor nanowires have recently been widely studied for use in integrated optoelectronic devices, such as light-emitting diodes (LEDs, solar cells, and transistors. Intensive research has also been conducted in the use of nanowires for subwavelength laser systems that take advantage of their quasione- dimensional (1D nature, flexibility in material choice and combination, and intrinsic optoelectronic properties. First, we provide an overview on using quasi-1D nanowire systems to realize subwavelength lasers with efficient, directional, and low-threshold emission. We then describe the state of the art for nanowire lasers in terms of materials, geometry, andwavelength tunability.Next,we present the basics of lasing in semiconductor nanowires, define the key parameters for stimulated emission, and introduce the properties of nanowires. We then review advanced nanowire laser designs from the literature. Finally, we present interesting perspectives for low-threshold nanoscale light sources and optical interconnects. We intend to illustrate the potential of nanolasers inmany applications, such as nanophotonic devices that integrate electronics and photonics for next-generation optoelectronic devices. For instance, these building blocks for nanoscale photonics can be used for data storage and biomedical applications when coupled to on-chip characterization tools. These nanoscale monochromatic laser light sources promise breakthroughs in nanophotonics, as they can operate at room temperature, can potentially be electrically driven, and can yield a better understanding of intrinsic nanomaterial properties and surface-state effects in lowdimensional semiconductor systems.

  12. Theoretical Researches on the Self-assembly System of Ciprofloxacin Imprinted Polymers

    Institute of Scientific and Technical Information of China (English)

    SUN Jia-Ni; LIU Jun-Bo; TANG Shan-Shan; JIN Rui-Fa

    2013-01-01

    A molecular modeling approach was used to elucidate template-monomer interaction and the effect of solvent on the recognition of molecularly imprinted polymers (MIPs).Ciprofloxacin (CIP) was taken as the template molecule.The methacrylic acid (MAA),4-vinyl pyridine (4-Vpy),acrylamide (AAM),and 2-(trifluoromethyl) acrylic acid (TFMAA) were taken as the functional monomers,respectively.Density functional theory (DFT) at the LC-WPBE/6-31g(d,p) level has been adopted to investigate the geometry optimization.The NBO charge and the binding energies of CIP with the monomers were carried out.The molecular imprinting mechanism of CIP and the monomers as well as the influence of solvent was also discussed.Results indicate that CIP and the monomers are matchable in steric structure and chemical groups lead to ordered compounds.The interaction between CIP and TFMAA is the strongest,and when the ratio of CIP-TFMAA is 1∶6,the polymer has the lowest energy in toluene.The computational approach has been applied to provide details of interactions between CIP and the monomers.This research will hopefully shed light on the future study of CIP-MIPs.

  13. Lithographically patterned nanowire electrodeposition

    Science.gov (United States)

    Xiang, Chengxiang

    Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M1 = silver or nickel) layer, 5 - 100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A photoresist (PR) layer is then deposited, photopatterned, and the exposed Ag or Ni is removed by wet etching. The etching duration is adjusted to produce an undercut ≈300 nm in width at the edges of the exposed PR. This undercut produces a horizontal trench with a precisely defined height equal to the thickness of theM1 layer. Within this trench, a nanowire of metal M2 is electrodeposited (M2 = gold, platinum, palladium, or bismuth). Finally the PR layer and M1 layer are removed. The nanowire height and width can be independently controlled down to minimum dimensions of 5 nm (h) and 11 nm (w), for example, in the case of platinum. These nanowires can be 1 cm in total length. We measure the temperature-dependent resistance of 100 um sections of Au and Pd wires in order to estimate an electrical grain size for comparison with measurements by X-ray diffraction and transmission electron microscopy. Nanowire arrays can be postpatterned to produce two-dimensional arrays of nanorods. Nanowire patterns can also be overlaid one on top of another by repeating the LPNE process twice in succession to produce, for example, arrays of low-impedance, nanowirenanowire junctions. The resistance, R, of single gold nanowires was measured in situ during electrooxidation in aqueous 0.10 M sulfuric acid. Electrooxidation caused the formation of a gold oxide that is approximately 0.8 monolayers (ML) in thickness at +1.1 V vs saturated mercurous sulfate reference electrode (MSE) based upon coulometry and ex situ X-ray photoelectron spectroscopic analysis. As the gold nanowires were electrooxidized, R increased by an amount that depended on the wire thickness, ranging from

  14. Constructing Novel Si@SnO2 Core-Shell Heterostructures by Facile Self-Assembly of SnO2 Nanowires on Silicon Hollow Nanospheres for Large, Reversible Lithium Storage.

    Science.gov (United States)

    Zhou, Zheng-Wei; Liu, Yi-Tao; Xie, Xu-Ming; Ye, Xiong-Ying

    2016-03-23

    Developing an industrially viable silicon anode, featured by the highest theoretical capacity (4200 mA h g(-1)) among common electrode materials, is still a huge challenge because of its large volume expansion during repeated lithiation-delithiation as well as low intrinsic conductivity. Here, we expect to address these inherent deficiencies simultaneously with an interesting hybridization design. A facile self-assembly approach is proposed to decorate silicon hollow nanospheres with SnO2 nanowires. The two building blocks, hand in hand, play a wonderful duet by bridging their appealing functionalities in a complementary way: (1) The silicon hollow nanospheres, in addition to the major role as a superior capacity contributor, also act as a host material (core) to partially accommodate the volume expansion, thus alleviating the capacity fading by providing abundant hollow interiors, void spaces, and surface areas. (2) The SnO2 nanowires serve as a conductive coating (shell) to enable efficient electron transport due to a relatively high conductivity, thereby improving the cyclability of silicon. Compared to other conductive dopants, the SnO2 nanowires with a high theoretical capacity (790 mA h g(-1)) can contribute outstanding electrochemical reaction kinetics, further adding value to the ultimate electrochemical performances. The resulting novel Si@SnO2 core-shell heterostructures exhibit remarkable synergy in large, reversible lithium storage, delivering a reversible capacity as high as 1869 mA h g(-1)@500 mA g(-1) after 100 charging-discharging cycles. PMID:26927734

  15. Solar heating of GaAs nanowire solar cells.

    Science.gov (United States)

    Wu, Shao-Hua; Povinelli, Michelle L

    2015-11-30

    We use a coupled thermal-optical approach to model the operating temperature rise in GaAs nanowire solar cells. We find that despite more highly concentrated light absorption and lower thermal conductivity, the overall temperature rise in a nanowire structure is no higher than in a planar structure. Moreover, coating the nanowires with a transparent polymer can increase the radiative cooling power by 2.2 times, lowering the operating temperature by nearly 7 K. PMID:26698787

  16. Solar heating of GaAs nanowire solar cells.

    Science.gov (United States)

    Wu, Shao-Hua; Povinelli, Michelle L

    2015-11-30

    We use a coupled thermal-optical approach to model the operating temperature rise in GaAs nanowire solar cells. We find that despite more highly concentrated light absorption and lower thermal conductivity, the overall temperature rise in a nanowire structure is no higher than in a planar structure. Moreover, coating the nanowires with a transparent polymer can increase the radiative cooling power by 2.2 times, lowering the operating temperature by nearly 7 K.

  17. Assembling one-dimensional coordination polymers into threedimensional architectures via hydrogen bonds

    Indian Academy of Sciences (India)

    Lalit Rajput; Madhushree Sarkar; Kumar Biradha

    2010-09-01

    The reactions of bis(pyridylcarboxamido)alkanes (amides) and bis(3-pyridyl)alkanediamides (reverse amides) with copper(II) and zinc(II) in the presence of various anions resulted in onedimensional polymeric crystalline complexes with or without guest inclusion. The crystal structure analyses of these complexes reveal that the one-dimensional networks observed here are of three types: simple linear chain, chains with wavy nature and chains containing cavities. The self-complementary amide groups of the ligands assembled these coordination networks into higher dimensional architectures via N-H$\\cdots$O hydrogen bonds.

  18. Fiber Optic pH Sensor with Self-Assembled Polymer Multilayer Nanocoatings

    Science.gov (United States)

    Shao, Li-Yang; Yin, Ming-Jie; Tam, Hwa-Yaw; Albert, Jacques

    2013-01-01

    A fiber-optic pH sensor based on a tilted fiber Bragg grating (TFBG) with electrostatic self-assembly multilayer sensing film is presented. The pH sensitive polymeric film, poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) was deposited on the circumference of the TFBG with the layer-by-layer (LbL) electrostatic self-assembly technique. The PDDA/PAA film exhibits a reduction in refractive index by swelling in different pH solutions. This effect results in wavelength shifts and transmission changes in the spectrum of the TFBG. The peak amplitude of the dominant spectral fringes over a certain window of the transmission spectrum, obtained by FFT analysis, has a near-linear pH sensitivity of 117 arbitrary unit (a.u.)/pH unit and an accuracy of ±1 a.u. (in the range of pH 4.66 to pH 6.02). The thickness and surface morphology of the sensing multilayer film were characterized to investigate their effects on the sensor's performance. The dynamic response of the sensor also has been studied (10 s rise time and 18 s fall time for a sensor with six bilayers of PDDA/PAA). PMID:23348031

  19. Fiber Optic pH Sensor with Self-Assembled Polymer Multilayer Nanocoatings

    Directory of Open Access Journals (Sweden)

    Hwa-Yaw Tam

    2013-01-01

    Full Text Available A fiber-optic pH sensor based on a tilted fiber Bragg grating (TFBG with electrostatic self-assembly multilayer sensing film is presented. The pH sensitive polymeric film, poly(diallyldimethylammonium chloride (PDDA and poly(acrylic acid (PAA was deposited on the circumference of the TFBG with the layer-by-layer (LbL electrostatic self-assembly technique. The PDDA/PAA film exhibits a reduction in refractive index by swelling in different pH solutions. This effect results in wavelength shifts and transmission changes in the spectrum of the TFBG. The peak amplitude of the dominant spectral fringes over a certain window of the transmission spectrum, obtained by FFT analysis, has a near-linear pH sensitivity of 117 arbitrary unit (a.u./pH unit and an accuracy of ±1 a.u. (in the range of pH 4.66 to pH 6.02. The thickness and surface morphology of the sensing multilayer film were characterized to investigate their effects on the sensor’s performance. The dynamic response of the sensor also has been studied (10 s rise time and 18 s fall time for a sensor with six bilayers of PDDA/PAA.

  20. Linear Assembles of BN Nanosheets, Fabricated in Polymer/BN Nanosheet Composite Film

    Directory of Open Access Journals (Sweden)

    Hong-Baek Cho

    2011-01-01

    Full Text Available Linear assembles of BN nanosheets (LABNs were fabricated in polysiloxane/BN nanosheet composite film under a high DC electric field. The hexagonal BN nanosheets were dispersed by sonication in a prepolymer mixture of polysiloxane followed by a high-speed mixing. The homogeneous suspension was cast on a spacer of microscale thickness and applied to a high DC electric field before it became cross-linked. X-ray diffraction, scanning electron microscopy, and digital microscopy revealed that LABNs formed in the polysiloxane matrix and that the BN nanosheets in the LABNs were aligned perpendicular to the film plane with high anisotropy. This is the first time that linear assemblies of nanosheets have been fabricated in an organic-inorganic hybrid film by applying a DC electric field. The enhanced thermal conductivity of the composite film is attributed to the LABNs. The LABN formation and heat conduction mechanisms are discussed. The polysiloxane/BN nanosheet composite film has the potential to be used semiconductor applications that require both a high thermal conductivity and a high electric insulation.

  1. Hierarchical self-assembly of nanoparticles in polymer matrix and the nature of the interparticle interaction

    Science.gov (United States)

    Lin, Yu-Chiao; Chen, Chun-Yu; Chen, Hsin-Lung; Hashimoto, Takeji; Chen, Show-An; Li, Yen-Cheng

    2015-06-01

    Using small angle X-ray scattering (SAXS), we elucidated the spatial organization of palladium (Pd) nanoparticles (NPs) in the polymer matrix of poly(2-vinylpyridine) (P2VP) and the nature of inter-nanoparticle interactions, where the NPs were synthesized in the presence of P2VP by the reduction of palladium acetylacetonate (Pd(acac)2). The experimental SAXS profiles were analysed on the basis of a hierarchical structure model considering the following two types of interparticle potential: (i) hard-core repulsion only (i.e., the hard-sphere interaction) and (ii) hard-core repulsion together with an attractive potential well (i.e., the sticky hard-sphere interaction). The corresponding theoretical scattering functions, which were used for analysing the experimental SAXS profiles, were obtained within the context of the Percus-Yevick closure and the Ornstein-Zernike equation in the fundamental liquid theory. The analyses revealed that existence of the attractive potential well is indispensable to account for the experimental SAXS profiles. Moreover, the morphology of the hybrids was found to be characterized by a hierarchical structure with three levels, where about six primary NPs with the diameter of ca. 1.8 nm (level one) formed local clusters (level two), and these clusters aggregated to build up a large-scale mass-fractal structure (level three) with the fractal dimension of ca. 2.3. The scattering function developed here is of general use for quantitatively characterizing the morphological structures of polymer/NP hybrids and, in particular, for exploring the interaction potential of the NPs on the basis of the fundamental liquid theory.

  2. Comb polymer architecture and particle size effects on the behavior of biphasic nanoparticle inks for direct-write assembly

    Science.gov (United States)

    Yoshikawa, Jun

    Biphasic nanoparticle mixtures composed of attractive and repulsive colloidal species enable the direct-write assembly of 3D structures with much finer features than those produced by pure colloidal gels. These mixtures rely on the use of comb polymer dispersants to render one particle population stable, while the other population is attractive. In this thesis, we systematically investigate the effects of comb polymer architecture and particle size ratio on the behavior of biphasic nanoparticle inks with the overarching aim of further advancing the direct-write assembly of 3D colloidal structures. We first investigated the effects of both pure polyelectrolytes, poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), and comb polymer dispersants composed of a PMAA backbone with methoxy-poly(ethylene oxide) (mPEO) teeth of varying molecular weights on the stability of barium titanate (BaTiO 3) suspensions. While each dispersant imparts stability to BaTiO 3 nanoparticles at low ionic strength (nanoparticle suspensions are studied. Shear elastic modulus, shear yield stress, and compressive yield stress are measured for mixtures of varying total volume fraction, attractive-to-repulsive volume fraction, and particle size ratio between attractive and repulsive species. Our observations indicate that the repulsive particles hinder the formation of the attractive gel network. The time required for shear elastic modulus to approach a steady-state value increases with the fraction of repulsive species. Furthermore, this behavior becomes more significant with increasing the repulsive particle size. Additionally, we find that biphasic suspensions composed of both identical and different mean particle sizes exhibit larger φ-scaling exponents for compressive yield stress than shear yield stress, indicating that such systems become more resistant to compression with increasing φ. This observation suggests that the biphasic suspensions flowing through fine nozzles are more

  3. Supramolecular Chemistry And Self-assembly Special Feature: Virus-assisted loading of polymer nanocontainer

    Science.gov (United States)

    Graff, Alexandra; Sauer, Marc; van Gelder, Patrick; Meier, Wolfgang

    2002-04-01

    We present a DNA-containing polymeric nanocontainer using the self-assembled superstructure of amphiphilic block copolymers in aqueous solutions. To demonstrate that DNA translocation is possible across a completely synthetic block copolymer membrane, we have used a phage transfection strategy as a DNA-transfer model system. For this purpose the bacterial channel forming protein LamB was reconstituted in ABA-triblock copolymer vesicles. The outer membrane protein LamB is a specific transporter for maltodextrins but also serves as a receptor for phage to trigger the ejection of phage DNA. We demonstrate that the functionality of the LamB protein is fully preserved despite the artificial surrounding. This leads to a type of polymeric vehicle for DNA that could be useful for gene therapy.

  4. Phase Change Nanodots Patterning using a Self-Assembled Polymer Lithography and Crystallization Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Raoux, S; Krebs, D; Krupp, L; Topuria, T; Caldwell, M; Milliron, D; Kellock, A; Rice, P; et. al.

    2008-01-01

    Crystallization behavior of scalable phase change materials can be studied on nanoscale structures. In this paper, high density ordered phase change nanodot arrays were fabricated using the lift-off technique on a self-assembled diblock copolymer template, polystyrene-poly(methyl-methacrylate). The size of the nanodots was less than 15 nm in diameter with 40 nm spacing. This method is quite flexible regarding the patterned materials and can be used on different substrates. The crystallization behavior of small scale phase change nanodot arrays was studied using time-resolved x-ray diffraction, which showed the phase transition for different materials such as Ge15Sb85, Ge2Sb2Te5, and Ag and In doped Sb2Te. The transition temperatures of these nanodot samples were also compared with their corresponding blanket thin films, and it was found that the nanodots had higher crystallization temperatures and crystallized over a broader temperature range.

  5. Fabrication of a molecular-level multilayer film on organic polymer surfaces via chemical bonding assembly.

    Science.gov (United States)

    Zhao, Hongchi; Yang, Peng; Deng, Jianping; Liu, Lianying; Zhu, Jianwu; Sui, Yuan; Lu, Jiaoming; Yang, Wantai

    2007-02-13

    A fresh multilayer film was fabricated on a molecular level and successfully tethered to the surface of a hydroxylated organic substrate via chemical bonding assembly (CBA). Sulfate anion groups (SO4-) were preintroduced onto the surface of biaxially oriented polypropylene (BOPP) films via a reference method. Upon hydrolysis of the SO4- groups, hydroxyl groups (--OH) were formed that subsequently acted as initial reagents for a series of alternate reactions with terephthalyl chloride (TPC) and bisphenol A (BPA). A stable and well-defined multilayer film was thus fabricated via the CBA method. As a result of the nanoscale multilayer fresh film being abundant with reactive groups, it is believed that the film and its fabrication method should provide a fundamental platform for further surface functionalization and direct the design of advanced materials with desired properties.

  6. Lithographically patterned nanowire electrodeposition: a method for patterning electrically continuous metal nanowires on dielectrics.

    Science.gov (United States)

    Xiang, Chenxiang; Kung, Sheng-Chin; Taggart, David K; Yang, Fan; Thompson, Michael A; Güell, Aleix G; Yang, Yongan; Penner, Reginald M

    2008-09-23

    Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M(1)=silver or nickel) layer, 5-100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A (+) photoresist (PR) layer is then deposited, photopatterned, and the exposed Ag or Ni is removed by wet etching. The etching duration is adjusted to produce an undercut approximately 300 nm in width at the edges of the exposed PR. This undercut produces a horizontal trench with a precisely defined height equal to the thickness of the M(1) layer. Within this trench, a nanowire of metal M(2) is electrodeposited (M(2)=gold, platinum, palladium, or bismuth). Finally the PR layer and M(1) layer are removed. The nanowire height and width can be independently controlled down to minimum dimensions of 5 nm (h) and 11 nm (w), for example, in the case of platinum. These nanowires can be 1 cm in total length. We measure the temperature-dependent resistance of 100 microm sections of Au and Pd wires in order to estimate an electrical grain size for comparison with measurements by X-ray diffraction and transmission electron microscopy. Nanowire arrays can be postpatterned to produce two-dimensional arrays of nanorods. Nanowire patterns can also be overlaid one on top of another by repeating the LPNE process twice in succession to produce, for example, arrays of low-impedance, nanowire-nanowire junctions.

  7. Polymer Vesicles as Robust Scaffolds for the Directed Assembly of Highly Crystalline Nanocrystals †

    KAUST Repository

    Wang, Mingfeng

    2009-12-15

    We report the incorporation of various inorganic nanoparticles (NPs) (PbS, LaOF, LaF3, and TiO2, each capped by oleic acid, and CdSe/ZnS core/shell QDs capped by trioctylphosphine oxide) into vesicles (d = 70-150 nm) formed by a sample of poly(styrene-b-acrylic acid) (PS4o4-b-PAA 62, where the subscripts refer to the degree of polymerization) in mixtures of tetrahydrofuran (THF), dioxane, and water. The block copolymer formed mixtures of crew-cut micelles and vesicles with some enhancement of the vesicle population when the NPs were present. The vesicle fraction could be isolated by selective sedimentation via centrifugation, followed by redispersion in water. The NPs appeared to be incorporated into the PAA layers on the internal and external walls of the vesicles (strongly favoring the former). NPs on the exterior surface of the vesicles could be removed completely by treating the samples with a solution of ethylenediaminetetraacetate (EDTA) in water. The triangular nanoplatelets of LaF3 behaved differently. Stacks of these platelets were incorporated into solid colloidal entities, similar in size to the empty vesicles that accompanied them, during the coassembly as water was added to the polymer/LaF3/THF/ dioxane mixture. © 2009 American Chemical Society.

  8. Surface functionalisation for the self-assembly of nanoparticle/polymer multilayer films

    International Nuclear Information System (INIS)

    The use of organosilanes as surface functionalising materials has been investigated as a precursor to the adsorption of ligand stabilised gold nanoparticles and the build-up of nanoparticle/polymer multilayer films. The purpose of surface functionalisation here is to produce a uniform surface with the maximum positive charge possible to enable the efficient adsorption of negatively charged gold nanoparticles. It is generally acknowledged that the characteristics of the first layer are important in determining the quality of the subsequent multilayer film and hence careful attention has been paid to its optimisation. Three aminosilanes have been investigated together with various methods for their deposition. The degree of nanoparticle adsorption in the resulting films was characterised using atomic force microscopy and X-ray photoelectron spectroscopy. The surface potential of the aminosilane films was also measured to provide information regarding the surface charge density. Our results show a strong correlation between the nanoparticle density and the initial surface charge density. Films of 3-aminopropyltriethoxysilane adsorbed from toluene yielded the highest level of nanoparticle adsorption

  9. Collective fluorescence switching of counterion-assembled dyes in polymer nanoparticles

    Science.gov (United States)

    Reisch, Andreas; Didier, Pascal; Richert, Ludovic; Oncul, Sule; Arntz, Youri; Mély, Yves; Klymchenko, Andrey S.

    2014-06-01

    The current challenge in the field of fluorescent nanoparticles (NPs) for bioimaging is to achieve extreme brightness and external control of their emission using biodegradable materials. Here we propose a new concept of fluorescent polymer NPs, doped with ionic liquid-like salts of a cationic dye (octadecyl rhodamine B) with a bulky hydrophobic counterion (fluorinated tetraphenylborate) that serves as spacer minimizing dye aggregation and self-quenching. The obtained 40-nm poly(D,L-lactide-co-glycolide) NPs containing up to 500 dyes are brighter than quantum dots and exhibit photo-induced reversible on/off fluorescence switching, never reported for dye-doped NPs. We show that this collective switching of hundreds of dyes is due to ultrafast excitation energy transfer and can be used for super-resolution imaging. These NPs, being spontaneously endocytosed by living cells, feature high signal-to-noise ratio and absence of toxicity. The counterion-based concept opens the way to a new class of nanomaterials for sensing, imaging and light harvesting.

  10. Functionalization of magnetic nanowires by charged biopolymers

    DEFF Research Database (Denmark)

    Magnin, D.; Callegari, V.; Mátéfi-Tempfli, Stefan;

    2008-01-01

    We report on a facile method for the preparation of biocompatible and bioactive magnetic nanowires. The method consists of the direct deposition of polysaccharides by layer-by-layer (LbL) assembly onto a brush of metallic nanowires; obtained by electrodeposition of the metal within the nanopores...... released by a gentle ultrasonic treatment. Transmission electron microscopy, electron energy-dispersive loss spectroscopy, and x-ray photoelectron spectroscopy indicate the formation of an homogeneous coating onto the nickel nanowires when one, two, or three CMP/CHI bilayers are deposited. This easy...

  11. Templated Synthesis of Magnetic Nanoparticles through the Self-Assembly of Polymers and Surfactants

    Directory of Open Access Journals (Sweden)

    Vo Thu An Nguyen

    2014-08-01

    Full Text Available The synthesis of superparamagnetic nanoparticles (NPs for various technological applications continues to be an interesting research topic. The successful application of superparamagnetic NPs to each specific area typically depends on the achievement of high magnetization for the nanocrystals obtained, which is determined by their average size and size distribution. The size dispersity of magnetic NPs (MNPs is markedly improved when, during the synthesis, the nucleation and growth steps of the reaction are well-separated. Tuning the nucleation process with the assistance of a hosting medium that encapsulates the precursors (such as self-assembled micelles, dispersing them in discrete compartments, improves control over particle formation. These inorganic-organic hybrids inherit properties from both the organic and the inorganic materials, while the organic component can also bring a specific functionality to the particles or prevent their aggregation in water. The general concept of interest in this review is that the shape and size of the synthesized MNPs can be controlled to some extent by the geometry and the size of the organic templates used, which thus can be considered as molds at the nanometer scale, for both porous continuous matrices and suspensions.

  12. Fabrication of Nanostructures Using Self-Assembled Peptides as Templates

    DEFF Research Database (Denmark)

    Castillo, Jaime

    2015-01-01

    the advantages of diphenylalanine are explained step by step offering new alternatives to fabricate nanostructures in a simple and rapid way. The chapter is complemented with techniques to manipulate the self-assembled diphenylalanine nanostructures without changing its properties during the manipulation process.......This chapter evaluates the use of a short-aromatic dipeptide, diphenylalanine, as a template in the fabrication of new nanostructures (nanowires, coaxial nanocables, nanochannels) using materials such as silicon, conducting and non-conducting polymers. Diphenylalanine self-organize...

  13. Self-assembled nanoscale coordination polymers carrying siRNAs and cisplatin for effective treatment of resistant ovarian cancer.

    Science.gov (United States)

    He, Chunbai; Liu, Demin; Lin, Wenbin

    2015-01-01

    Resistance to the chemotherapeutic agent cisplatin is a major limitation for the successful treatment of many cancers. Development of novel strategies to overcome intrinsic and acquired resistance to chemotherapy is of critical importance to effective treatment of ovarian cancer and other types of cancers. We have sought to re-sensitize resistant ovarian cancer cells to chemotherapy by co-delivering chemotherapeutics and pooled siRNAs targeting multi-drug resistance (MDR) genes using self-assembled nanoscale coordination polymers (NCPs). In this work, NCP-1 particles with trigger release properties were first constructed by linking cisplatin prodrug-based bisphosphonate bridging ligands with Zn(2+) metal-connecting points and then coated with a cationic lipid layer, followed by the adsorption of pooled siRNAs targeting three MDR genes including survivin, Bcl-2, and P-glycoprotein via electrostatic interactions. The resulting NCP-1/siRNA particles promoted cellular uptake of cisplatin and siRNA and enabled efficient endosomal escape in cisplatin-resistant ovarian cancer cells. By down-regulating the expression of MDR genes, NCP-1/siRNAs enhanced the chemotherapeutic efficacy as indicated by cell viability assay, DNA ladder, and flow cytometry. Local administration of NCP-1/siRNAs effectively reduced tumor sizes of cisplatin-resistant SKOV-3 subcutaneous xenografts. This work shows that the NCP-1/siRNA platform holds great promise in enhancing chemotherapeutic efficacy for the effective treatment of drug-resistant cancers.

  14. Reversible pH Stimulus-Response Material Based on Amphiphilic Block Polymer Self-Assembly and Its Electrochemical Application

    Directory of Open Access Journals (Sweden)

    Tianyi Wang

    2016-06-01

    Full Text Available Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene–b–polyacrylic acid (PS–b–PAA. The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4–9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.

  15. Facile Synthesis of Gold-nanoparticles-decorated Polymer Assemblies and Core-Shell Gold Nanoparticles Using Pluronic Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    SHOU Qing-hui; GUO Chen; GAO Hong-shuai; ZHOU Hua-cong; LIU Chun-zhao; LIU Hui-zhou

    2011-01-01

    Abstract:Synthesis of gold nanoparticles (AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied.Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules or pH value of the P123 solution.When a lower volume ratio of [AuCl4-]/[P123] (0.05) was employed at pH 11.1,a nanostructure similar to plum pudding was obtained.AuNPs with an average diameter of 13.1 nm were embedded in Pluronic assemblies,and each one held about 21 single gold nanoparticles.When [AuCl4-]/[P123] was increased to 0.1,core-shell structure was obtained if the pH value was in the range of 10.6~11.6,while gold polyhedra were fabricated when pH value was 8.1.Typical core-shell AuNPs had an average diameter of 9.6 nm with a narrow size distribution,while gold polyhedras with a mean diameter of 12.8 nm was obtained.The specific morphologies of the resultant nanocomposite were presumably obtained due to the synergistic interaction among the reactants.

  16. Different aliphatic dicarboxylates affected assemble of new coordination polymers constructed from flexible-rigid mixed ligands

    International Nuclear Information System (INIS)

    In this article, seven coordination polymers: [Cd(C5H6O4)(C10H8N2)]n (1), [Zn(C5H6O4)(C10H8N2)]n (2), [Cd(C6H8O4)(C10H8N2)]n (3), {[Mn(C10H8N2)(H2O)4] (C4H4O4).4H2O}n (4), [Mn5(C4H4O4)4(O)]n (5), [Cd(C4H4O4)(C10H8N2)(H2O)]n (6) and [Zn(C6H6O4)(C12H8N2)(H2O)]n (7) were synthesized and characterized by single-crystallographic X-ray diffraction. Compounds 1 and 2 are two-dimensional layers connected by glutarate anions and 4,4'-bpy. Unlike compounds 1 and 2, compound 3 is a two-fold interpenetration network. Compound 4 is a one-dimensional chain-like structure, which is further extended to two-dimensional supramolecular layer structure with hydrogen bond. During the synthesis of compound 4, to our surprise, we got compound 5; compound 5 is an interesting three-dimensional network composed of pentanuclear Mn(II) building units and succinate anions. Compound 6 is also a two-dimensional supramolecular layer structure composed of one-dimensional chain-like structure with hydrogen bonds and Π-Π interactions. Compound 7 is also a one-dimensional chain-like structure, which is further connected with the same kind of interaction to generate two-dimensional supramolecular layer structure. Furthermore, compounds 1 and 2 both exhibit fluorescent property at room temperature. - Graphical abstract: Seven complexes composed by 3D metal ions, aliphatic acid ligand and rigid bidentate nitrogen ligands: 4,4'-bpy, 2,2'-bpy and 1,10'-phen. With the change of the carbon number of the backbone of aliphatic dicarboxylate ligand, we can synthesize different complexes with various structures

  17. Annealing-free and strongly adhesive silver nanowire networks with long-term reliability by introduction of a nonconductive and biocompatible polymer binder

    Science.gov (United States)

    Jin, Yunxia; Deng, Dunying; Cheng, Yuanrong; Kong, Lingqiang; Xiao, Fei

    2014-04-01

    As a promising candidate to replace the brittle and expensive transparent indium tin oxide (ITO) conductor, the use of silver nanowire (AgNW) networks still involves issues such as high-temperature post-treatments and poor substrate adhesion for industrial application. Here a room-temperature soldering and one-step solution method is developed to achieve high-performance Ag nanowire transparent conductive films (TCFs). A nonconductive binder is prepared from poly(dopamine) and alginic acid which contains abundant catechol and carboxylic acid functional groups. The drying of the binder on the Ag nanowire percolation networks induces tighter contact among the nanowires and strong adhesion to the substrate, simultaneously enhancing the electrical and mechanical properties without a high-temperature annealing process. As a result, a highly conductive and bendable AgNW film is demonstrated on a low-cost polyethylene glycol terephthalate (PET) substrate, showing an 89% optical transmittance at λ = 550 nm and a sheet resistance of 16.3 Ohm sq-1. Its optical and electrical performances are superior to those obtained from the reported indium tin oxide (ITO) films. Moreover, the AgNW film exhibits strong adhesion to the substrate, maintaining its conductivity after 100 tape tests, and it still resists the tape test even after exposure to solvent for several hours. Most importantly, the film shows good reliability during long-term 85 °C/85% RH (relative humidity) aging, which has been rarely investigated although it is a critical requirement for industrial application. The advanced and wide-ranging features of the prepared AgNW film greatly contribute to its use as a transparent electrode in multifunctional flexible electronic devices.

  18. Helical Growth of Ultrathin Gold-Copper Nanowires.

    Science.gov (United States)

    Mendoza-Cruz, Rubén; Bazán-Díaz, Lourdes; Velázquez-Salazar, J Jesús; Plascencia-Villa, Germán; Bahena-Uribe, Daniel; Reyes-Gasga, José; Romeu, David; Guisbiers, Grégory; Herrera-Becerra, Raúl; José-Yacamán, Miguel

    2016-03-01

    In this work, we report the synthesis and detailed structural characterization of novel helical gold-copper nanowires. The nanowires possess the Boerdijk-Coxeter-Bernal structure, based on the pile up of octahedral, icosahedral, and/or decahedral seeds. They are self-assembled into a coiled manner as individual wires or into a parallel-ordering way as groups of wires. The helical nanowires are ultrathin with a diameter of less than 10 nm and variable length of several micrometers, presenting a high density of twin boundaries and stacking faults. To the best of our knowledge, such gold-copper nanowires have never been reported previously. PMID:26849249

  19. Imaging Electrogenerated Chemiluminescence at Single Gold Nanowire Electrodes.

    Science.gov (United States)

    Wilson, Andrew J; Marchuk, Kyle; Willets, Katherine A

    2015-09-01

    We report electrogenerated chemiluminescence (ECL) generated at single gold nanowire electrodes supported on tin-doped indium oxide. Unlike other single nanoparticle electrochemical characterization techniques, ECL provides a massively parallel direct readout of electrochemical activity on individual nanoparticle electrodes without the need for extrinsic illumination or a scanning electrochemical probe. While ECL is not observed from as-purchased nanowires due to the surfactant layer, by removing the layer and coating the nanowires with a polymer blend, ECL from single nanowire electrodes is readily measured. With an increase in polymer thickness, an increase in ECL image quality and reproducibility over multiple redox cycles is observed. The polymer coating also provides a strategy for stabilizing gold nanoparticle electrodes against complete surface oxidation in aqueous environments. PMID:26267267

  20. Electrochemical synthesis of CORE-shell magnetic nanowires

    KAUST Repository

    Ovejero, Jesús G.

    2015-04-16

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloys). Novel opportunities offered by such nanowires are discussed particularly the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare TM nanowires. These core-shell nanowires can be released from the template so, opening novel opportunities for biofunctionalization of individual nanowires.

  1. Covalent deposition of zwitterionic polymer and citric acid by click chemistry-enabled layer-by-layer assembly for improving the blood compatibility of polysulfone membrane.

    Science.gov (United States)

    Xiang, Tao; Wang, Rui; Zhao, Wei-Feng; Sun, Shu-Dong; Zhao, Chang-Sheng

    2014-05-13

    Development of blood compatible membranes is critical for biomedical applications. Zwitterionic polymers have been proved to be resistant to nonspecific protein adsorption and platelet adhesion. In this work, two kinds of zwitterionic copolymers bearing alkynyl and azide groups are synthesized by atom transfer radical polymerization (ATRP) and subsequent reactions, namely alkynyl-poly(sulfobetaine methacrylate) (alkynyl-PSBMA) and azide-poly(sulfobetaine methacrylate) (azide-PSBMA). The copolymers are directly used to modify azido-functionalized polysulfone (PSf-N3) membrane via click chemistry-enabled layer-by-layer (LBL) assembly. Alkynyl-citric acid is then clicked onto the membrane when the outermost layer was azide-PSBMA. The chemical compositions, surface morphologies, and hydrophilicity of the zwitterionic polymer and citric acid multilayer modified membranes are characterized. The composite multilayer is resistant to protein adsorption and platelet adhesion and also prolongs clotting times, indicating that the blood compatibility is improved. Moreover, after clicking the small molecule anticoagulant alkynyl-citric acid onto the outermost of the zwitterionic multilayer, the membrane shows further improved anticoagulant property. The deposition of zwitterionic polymer and citric acid via click chemistry-enabled LBL assembly can improve the blood compatibility of the PSf membrane.

  2. Nanowire photonics

    OpenAIRE

    Peter J. Pauzauskie; Peidong Yang

    2006-01-01

    The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. Howev...

  3. Characterization of self-assembled monolayers (SAMs) on silicon substrate comparative with polymer substrate for Escherichia coli O157:H7 detection

    Science.gov (United States)

    Moldovan, Carmen; Mihailescu, Carmen; Stan, Dana; Ruta, Lavinia; Iosub, Rodica; Gavrila, Raluca; Purica, Munizer; Vasilica, Schiopu

    2009-08-01

    This article presents the characterization of two substrates, silicon and polymer coated with gold, that are functionalized by mixed self-assembled monolayers (SAMs) in order to efficiently immobilize the anti- Escherichia coli O157:H7 polyclonal purified antibody. A biosurface functionalized by SAMs (self-assembled monolayers) technique has been developed. Immobilization of goat anti- E. coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayers (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold. The F(ab') 2 fragments of the antibodies have been used for eliminating nonspecific bindings between the Fc portions of antibodies and the Fc receptor on cells. The properties of the monolayers and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FTIR-ATR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and cyclic voltammetry (CV). In our study the gold-coated silicon substrates approach yielded the best results. These experimental results revealed the necessity to investigate each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions as well and also provide a solid basis for further studies aiming at elaborating sensitive and specific immunosensor or a microarray for the detection of E. coli O157:H7.

  4. Characterization of self-assembled monolayers (SAMs) on silicon substrate comparative with polymer substrate for Escherichia coli O157:H7 detection

    Energy Technology Data Exchange (ETDEWEB)

    Moldovan, Carmen, E-mail: carmen.moldovan@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Mihailescu, Carmen, E-mail: carmen_mihail28@yahoo.com [University of Bucharest, 90-92 Sos Panduri, Bucharest (Romania); Stan, Dana, E-mail: dana_stan2005@yahoo.com [DDS Diagnostic, 1 Segovia Street, Bucharest (Romania); Ruta, Lavinia, E-mail: laviniacoco@yahoo.com [University of Bucharest, 90-92 Sos Panduri, Bucharest (Romania); Iosub, Rodica, E-mail: rodica.iosub@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Gavrila, Raluca, E-mail: raluca.gavrila@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Purica, Munizer, E-mail: munizer.purica@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania); Vasilica, Schiopu, E-mail: vasilica.schiopu@imt.ro [National Institute for R and D in Microtechnologies, IMT-Bucharest, 126A Erou Iancu Nicolae, 077190 Bucharest (Romania)

    2009-08-30

    This article presents the characterization of two substrates, silicon and polymer coated with gold, that are functionalized by mixed self-assembled monolayers (SAMs) in order to efficiently immobilize the anti-Escherichia coli O157:H7 polyclonal purified antibody. A biosurface functionalized by SAMs (self-assembled monolayers) technique has been developed. Immobilization of goat anti-E. coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayers (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold. The F(ab'){sub 2} fragments of the antibodies have been used for eliminating nonspecific bindings between the Fc portions of antibodies and the Fc receptor on cells. The properties of the monolayers and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FTIR-ATR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and cyclic voltammetry (CV). In our study the gold-coated silicon substrates approach yielded the best results. These experimental results revealed the necessity to investigate each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions as well and also provide a solid basis for further studies aiming at elaborating sensitive and specific immunosensor or a microarray for the detection of E. coli O157:H7.

  5. Actuation of polypyrrole nanowires

    Science.gov (United States)

    Lee, Alexander S.; Peteu, Serban F.; Ly, James V.; Requicha, Aristides A. G.; Thompson, Mark E.; Zhou, Chongwu

    2008-04-01

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 µm, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  6. Actuation of polypyrrole nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Alexander S; Peteu, Serban F; Ly, James V; Requicha, Aristides A G; Thompson, Mark E; Zhou Chongwu [Laboratory for Molecular Robotics, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: requicha@usc.edu

    2008-04-23

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 {mu}m, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  7. Actuation of polypyrrole nanowires.

    Science.gov (United States)

    Lee, Alexander S; Peteu, Serban F; Ly, James V; Requicha, Aristides A G; Thompson, Mark E; Zhou, Chongwu

    2008-04-23

    Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 µm, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

  8. Combing non-epitaxially grown nanowires for large-area electronic devices

    International Nuclear Information System (INIS)

    A facile route for aligning randomly oriented nanowires synthesized by a vapor–liquid–solid method for the fabrication of nanoelectronic devices was achieved using a polymer combing technique. By controlling the Young’s modulus of the polymer combs, van der Waals interactions and shearing forces between the combs and nanowires can be manipulated and thus the nanowire density and alignment can be controlled. Using the proposed method, field-effect transistors were directly fabricated on as-grown substrates after aligning the nanowires, thereby demonstrating the feasibility of the scheme for the production of nanoelectronic devices. (paper)

  9. Gibbs-Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth.

    Science.gov (United States)

    Shen, Youde; Chen, Renjie; Yu, Xuechao; Wang, Qijie; Jungjohann, Katherine L; Dayeh, Shadi A; Wu, Tom

    2016-07-13

    Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices. PMID:27254592

  10. Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

    KAUST Repository

    Shen, Youde

    2016-06-02

    Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor-liquid-solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs-Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs-Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices. © 2016 American Chemical Society.

  11. Charge-driven and reversible assembly of ultra-dense polymer brushers: Formation and antifouling properties of a zipper brush

    NARCIS (Netherlands)

    Vos, de W.M.; Meijer, G.; Keizer, de A.; Cohen Stuart, M.A.; Kleijn, J.M.

    2010-01-01

    We investigated a new type of polymer brushes: the zipper brush. By adsorbing a diblock-copolymer with one charged block and one neutral block to an oppositely charged polyelectrolyte brush, a neutral polymer brush is formed on top of an almost neutral complex layer of polyelectrolytes. This neutral

  12. Unique self-assembly behavior of a triblock copolymer and fabrication of catalytically active gold nanoparticle/polymer thin films at the liquid/liquid interface

    International Nuclear Information System (INIS)

    Gold nanoparticle-doped poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) thin films were prepared at the planar liquid/liquid interface between the chloroform solution of the polymer and aqueous solution of HAuCl4. Transmission electron microscopic (TEM) investigations revealed that foam films composed of microcapsules as well as one-dimensional belts were formed, and numerous Au nanoparticles were incorporated in the walls of the microcapsules and the nanobelts. The walls and the belts have layered structure. The formation mechanism of the foams and the belts was attributed to adsorption of the polymer molecules, combination of the polymer molecules with AuCl4− ions, microphase separation and self-assembly of the composite molecules at the interface. This microstructure is different apparently from those formed in solutions, in casting or spin-coating thin films and at the air/water interface of this triblock copolymer, reflecting unique self-assembly behavior at the liquid/liquid interface. This microstructure is also different from those formed by homo-P2VP and P4VP-b-PS-b-P4VP at the liquid/liquid interface, indicating the effects of molecular structures on the self-assembly behaviors of the polymers. After further treatment by UV-light irradiation and KBH4 aqueous solution, the gold species were reduced completely, as indicated by UV–vis spectra and X-ray photoelectron spectra (XPS). Thermogravimetric analysis indicated that the composite films have high thermal stability, and the content of gold was estimated to be about 9.1%. These composite films exhibited high catalytic activity for the reduction of 4-nitrophenol by KBH4 in aqueous solutions. - Highlights: • P2VP-b-PS-b-P2VP formed microcapsules and nanobelts at the liquid/liquid interface. • Its self-assembly behavior differs from P4VP-b-PS-b-P4VP at the interface. • This behavior also differs from those in solution, in film and at air/water interface.

  13. Self-Assembly of 1D/2D Hybrid Nanostructures Consisting of a Cd(II Coordination Polymer and NiAl-Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Gonzalo Abellán

    2015-12-01

    Full Text Available The preparation and characterization of a novel hybrid material based on the combination of a 2D-layered double hydroxide (LDH nanosheets and a 1D-coordination polymer (1D-CP has been achieved through a simple mixture of suspensions of both building blocks via an exfoliation/restacking approach. The hybrid material has been thoroughly characterized demonstrating that the 1D-CP moieties are intercalated as well as adsorbed on the surface of the LDH, giving rise to a layered assembly with the coexistence of the functionalities of their initial constituents. This hybrid represents the first example of the assembly of 1D/2D nanomaterials combining LDH with CP and opens the door for a plethora of different functional hybrid systems.

  14. Direct growth of urchin-like ZnCo2O4 microspheres assembled from nanowires on nickel foam as high-performance electrodes for supercapacitors

    International Nuclear Information System (INIS)

    Graphical abstract: Conductive nickel foam supported urchin-like ZnCo2O4 microspheres composed of ultrafine nanowires with superior supercapacitive performance have been achieved. Display Omitted -- Highlights: • Conductive Ni foam supported urchin-like ZnCo2O4 microspheres have been prepared. • ZnCo2O4 microspheres possess large specific surface area and mesoporous structure. • The ZnCo2O4 microspheres show excellent supercapacitive performance. -- Abstract: Urchin-like ZnCo2O4 microspheres grown on nickel foam have been successfully prepared by a two-step facile strategy involving hydrothermal method and subsequent thermal annealing treatment. The as-obtained nickel foam supported urchin-like ZnCo2O4 microspheres can be directly used as the electrodes for the supercapacitors. The physical characterizations indicate that the hierarchical urchin-like ZnCo2O4 microspheres are composed of numerous nanowires and have a large specific surface area of 84.8 m2 g−1, which are beneficial for the electron and ion transport and the increase of electroactive surface areas. In addition, the electrochemical properties of the urchin-like ZnCo2O4 microspheres as binder-free electrode for supercapacitor are studied by cyclic voltammetry, current charge-discharge, electrochemical impedance spectroscopy, and cycle life measurements in 6 M KOH electrolyte. The urchin-like ZnCo2O4 microspheres electrode exhibits a high capacitance of 1841.8 F g−1 at a current density of 1 A g−1 and keeps the capacitance retention about 78.4% at 10 A g−1. After 3000 cycles, the specific capacitance is about 1390.1 F g−1 at a current density of 10 A g−1, and it also shows the excellent cycling stability (95.8%). All the results demonstrate that the urchin-like ZnCo2O4 microspheres supported on nickel foam have great potential as high-performance electrodes for supercapacitors

  15. Self-assembly thermodynamics of pH-responsive amino-acid-based polymers with a nonionic surfactant.

    Science.gov (United States)

    Bogomolova, Anna; Keller, Sandro; Klingler, Johannes; Sedlak, Marian; Rak, Dmytro; Sturcova, Adriana; Hruby, Martin; Stepanek, Petr; Filippov, Sergey K

    2014-09-30

    The behavior of pH-responsive polymers poly(N-methacryloyl-l-valine) (P1), poly(N-methacryloyl-l-phenylalanine) (P2), and poly(N-methacryloylglycyne-l-leucine) (P3) has been studied in the presence of the nonionic surfactant Brij98. The pure polymers phase-separate in an acidic medium with critical pHtr values of 3.7, 5.5, and 3.4, respectively. The addition of the surfactant prevents phase separation and promotes reorganization of polymer molecules. The nature of the interaction between polymer and surfactant depends on the amino acid structure in the side chain of the polymer. This effect was investigated by dynamic light scattering, isothermal titration calorimetry, electrophoretic measurements, small-angle neutron scattering, and infrared spectroscopy. Thermodynamic analysis revealed an endothermic association reaction in P1/Brij98 mixture, whereas a strong exothermic effect was observed for P2/Brij98 and P3/Brij98. Application of regular solution theory for the analysis of experimental enthalpograms indicated dominant hydrophobic interactions between P1 and Brij98 and specific interactions for the P2/Brij98 system. Electrophoretic and dynamic light scattering measurements support the applicability of the theory to these cases. The specific interactions can be ascribed to hydrogen bonds formed between the carboxylic groups of the polymer and the oligo(ethylene oxide) head groups of the surfactant. Thus, differences in polymer-surfactant interactions between P1 and P2 polymers result in different structures of polymer-surfactant complexes. Specifically, small-angle neutron scattering revealed pearl-necklace complexes and "core-shell" structures for P1/Brij98 and P2/Brij98 systems, respectively. These results may help in the design of new pH-responsive site-specific micellar drug delivery systems or pH-responsive membrane-disrupting agents.

  16. Nanowire Optoelectronics

    Directory of Open Access Journals (Sweden)

    Wang Zhihuan

    2015-12-01

    Full Text Available Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, light-emitting diodes (LEDs, lasers, sensors, and optical antennas. We review the optical properties of these nanowires in terms of absorption, guiding, and radiation of light, which may be termed light management. Analysis of the interaction of light with long cylindrical/hexagonal structures with subwavelength diameters identifies radial resonant modes, such as Leaky Mode Resonances, or Whispering Gallery modes. The two-dimensional treatment should incorporate axial variations in “volumetric modes,”which have so far been presented in terms of Fabry–Perot (FP, and helical resonance modes. We report on finite-difference timedomain (FDTD simulations with the aim of identifying the dependence of these modes on geometry (length, width, tapering, shape (cylindrical, hexagonal, core–shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how nanowires (NWs form excellent optical cavities without the need for top and bottommirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption and downward transitions (emission of light inNWs; rather, the electronic transition rates should be considered. We discuss this “rate management” scheme showing its strong dimensional dependence, making a case for photonic integrated circuits (PICs that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.

  17. Surface-Directed Assembly of Sequence-Defined Synthetic Polymers into Networks of Hexagonally Patterned Nanoribbons with Controlled Functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chun-Long; Zuckermann, Ronald N.; DeYoreo, James J.

    2016-05-24

    The exquisite self-assembly of proteins and peptides in nature into highly ordered functional materials has inspired innovative approaches to biomimetic materials design and synthesis. Here we report the assembly of peptoids—a class of highly stable sequence-defined synthetic polymers—into biomimetic materials on mica surfaces. The assembling 12-mer peptoid contains alternating acidic and aromatic residues, and the presence of Ca2+ cations creates peptoid-peptoid and peptoid-mica interactions that drive assembly. In situ atomic force microscopy (AFM) shows that peptoids first assemble into discrete nanoparticles, these particles then transform into hexagonally-patterned nanoribbons on mica surfaces. AFM-based dynamic force spectroscopy (DFS) studies show that peptoid-mica interactions are much stronger than peptoidpeptoid interactions in the presence of Ca2+, illuminating the physical parameters that drive peptoid assembly. We further demonstrate the display of functional groups at the N-terminus of assembling peptoid sequence to produce biomimetic materials with similar hierarchical structures. This research demonstrates that surface-directed peptoid assembly can be used as a robust platform to develop biomimetic coating materials for applications.

  18. Burnout current density of bismuth nanowires

    Science.gov (United States)

    Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.; Völklein, F.; Karim, S.; Duan, J. L.

    2008-05-01

    Single bismuth nanowires with diameters ranging from 100nmto1μm were electrochemically deposited in ion track-etched single-pore polycarbonate membranes. The maximum current density the wires are able to carry was investigated by ramping up the current until failure occurred. It increases by three to four orders of magnitude for nanowires embedded in the template compared to bulk bismuth and rises with diminishing diameter. Simulations show that the wires are heated up electrically to the melting temperature. Since the surface-to-volume ratio rises with diminishing diameter, thinner wires dissipate the heat more efficiently to the surrounding polymer matrix and, thus, can tolerate larger current densities.

  19. Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement.

    Science.gov (United States)

    Zeng, Xiaoliang; Yao, Yimin; Gong, Zhengyu; Wang, Fangfang; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-12-01

    Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.

  20. Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement.

    Science.gov (United States)

    Zeng, Xiaoliang; Yao, Yimin; Gong, Zhengyu; Wang, Fangfang; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-12-01

    Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates. PMID:26479262

  1. Design, construction, and testing a purpose-built climate-controlled solvent vapor annealing chamber for guided self-assembly of block polymer thin films

    Science.gov (United States)

    Gnabasik, Ryan; Haase, Rustin; Baruth, Andrew

    2014-03-01

    Despite its efficacy to produce well-ordered, periodic nanostructures, the intricate role multiple parameters play in solvent vapor annealing has not been fully established. In solvent vapor annealing a thin polymer film is exposed to the vapors of a solvent(s) thus forming a swollen and mobile layer to direct the self-assembly process at the nanoscale. Recent developments in both theory and experiment have directly identified critical parameters, but controlling them in any systematic way has proven non-trivial. These identified parameters include vapor pressure, solvent concentration in the film, and, critically, the solvent evaporation rate. To explore their role, a purpose-built solvent vapor annealing chamber was designed and constructed. The all-metal chamber is inert to solvent exposure and pneumatically actuated valves allow for precision timing in the introduction and withdrawal of solvent vapor. Furthermore, the mass flow controlled inlet, chamber pressure gauges, in situ spectral reflectance-based thickness monitoring, and high precision micrometer relief valve, give real-time monitoring and control during the annealing and evaporation phases. Using atomic force microscopy to image the annealed films, we are able to map out the parameter space for a series of polystyrene- b-polylactide (Mn = 75 kg/mol and fPLA = 0.28) block polymer thin films with an intrinsic cylindrical morphology and identify their role in directed assembly. Funded by Creighton University Summer Research Grant.

  2. Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration.

    Science.gov (United States)

    Wan, Jiangshan; Geng, Shinan; Zhao, Hao; Peng, Xiaole; Zhou, Qing; Li, Han; He, Ming; Zhao, Yanbing; Yang, Xiangliang; Xu, Huibi

    2016-08-10

    Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy. PMID:27282415

  3. Patchy Supramolecular Bottle-Brushes Formed by Solution Self-Assembly of Bis(urea)s and Tris(urea)s Decorated by Two Incompatible Polymer Arms.

    Science.gov (United States)

    Catrouillet, Sylvain; Bouteiller, Laurent; Boyron, Olivier; Lorthioir, Cédric; Nicol, Erwan; Pensec, Sandrine; Colombani, Olivier

    2016-09-01

    In an attempt to design urea-based Janus nanocylinders through a supramolecular approach, nonsymmetrical bis(urea)s and tris(urea)s decorated by two incompatible polymer arms, namely, poly(styrene) (PS) and poly(isobutylene) (PIB), were synthesized using rather straightforward organic and polymer chemistry techniques. Light scattering experiments revealed that these molecules self-assembled in cyclohexane by cooperative hydrogen bonds. The extent of self-assembly was limited for the bis(urea)s. On the contrary, reasonably anisotropic 1D structures (small nanocylinders) could be obtained with the tris(urea)s (Nagg ∼ 50) which developed six cooperative hydrogen bonds per molecule. (1)H transverse relaxation measurements and NOESY NMR experiments in cyclohexane revealed that perfect Janus nanocylinders with one face consisting of only PS and the other of PIB were not obtained. Nevertheless, phase segregation between the PS and PIB chains occurred to a large extent, resulting in patchy cylinders containing well separated domains of PIB and PS chains. Reasons for this behavior were proposed, paving the way to improve the proposed strategy toward true urea-based supramolecular Janus nanocylinders.

  4. Assemblies of gold icosahedra

    OpenAIRE

    Bilalbegovic, G.

    2004-01-01

    Low-dimensional free-standing aggregates of bare gold clusters are studied by the molecular dynamics simulation. Icosahedra of 55 and 147 atoms are equilibrated at T=300 K. Then, their one- and two-dimensional assemblies are investigated. It is found that icosahedra do not coalescence into large drops, but stable amorphous nanostructures are formed: nanowires for one-dimensional and nanofilms for two-dimensional assemblies. The high-temperature stability of these nanostructures is also invest...

  5. Syntheses and Characterizations of Novel One-dimensional Coordination Polymers Self-assembled from Co(NCS)2 and Flexible Diester-bridged Pyridine-based Ligands

    Institute of Scientific and Technical Information of China (English)

    SONG,Li-Cheng(宋礼成); ZHANG,Wen-Xiong(张文雄); HU,Qing-Mei(胡青眉)

    2002-01-01

    The self-assembly reactions of Co(NCS)2 with diester-bridgedpyridine-based ligands pyCO2-(CH2),-O2Cpy (py= 4-pyridyl;m = 2, 3, 4) have been studied. Interestingly, while Co(NCS)2 reacted with pyCO2-(CH2)2-O2Cpy (La) in MeOH/H2Oor THF/MeCN to yield two coordination polymers [Co(NCS)2(La)2]n (1) and [Co(NCS)2(La)2@2THF]n (2), reactions of Co(NCS)2 with pyCO2-(CH2)3-O2Cpy (Lb) in MeOH/MeCN and Co(NCS)2 with pyCO2-( CH2)4-O2Cpy(Lc) in EtOH/H2O afforded [Co(NCS)2(Lb)2@0.5MeOH]n(3) and [Co(NCS)2(Lc)2@2H2O]n (4), respectively. The Xray diffraction analyses indicated that polymers 1-4 consist of a one-dimensional Co(H) chain in which each of the two adjacent Co(Ⅱ) ions is bridged by two pyCO2-(CH2)m-O2Cpy ligands to form a macrocycle, In addition, the structuress of polymers 1-4 were also characterized by infrared spectroscopy,thermogravimetry and elemental analysis.

  6. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan

    2016-05-28

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  7. Nanoporous polymer electrolyte

    Science.gov (United States)

    Elliott, Brian; Nguyen, Vinh

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  8. Langmuir-Blodgettry of nanocrystals and nanowires.

    Science.gov (United States)

    Tao, Andrea R; Huang, Jiaxing; Yang, Peidong

    2008-12-01

    Although nanocrystals and nanowires have proliferated new scientific avenues in the study of their physics and chemistries, the bottom-up assembly of these small-scale building blocks remains a formidable challenge for device fabrication and processing. An attractive nanoscale assembly strategy should be cheap, fast, defect tolerant, compatible with a variety of materials, and parallel in nature, ideally utilizing the self-assembly to generate the core of a device, such as a memory chip or optical display. Langmuir-Blodgett (LB) assembly is a good candidate for arranging vast numbers of nanostructures on solid surfaces. In the LB technique, uniaxial compression of a nanocrystal or nanowire monolayer floating on an aqueous subphase causes the nanostructures to assemble and pack over a large area. The ordered monolayer can then be transferred to a solid surface en masse and with fidelity. In this Account, we present the Langmuir-Blodgett technique as a low-cost method for the massively parallel, controlled organization of nanostructures. The isothermal compression of fluid-supported nanoparticles or nanowires is unique in its ability to achieve control over nanoscale assembly by tuning a macroscopic property such as surface pressure. Under optimized conditions (e.g., surface pressure, substrate hydrophobicity, and pulling speed), it allows continuous variation of particle density, spacing, and even arrangement. For practical application and device fabrication, LB compression is ideal for forming highly dense assemblies of nanowires and nanocrystals over unprecedented surface areas. In addition, the dewetting properties of LB monolayers can be used to further achieve patterning within the range of micrometers to tens of nanometers without a predefined template. The LB method should allow for easy integration of nanomaterials into current manufacturing schemes, in addition to fast device prototyping and multiplexing capability. PMID:18683954

  9. Vertical nanowire architectures

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfl-Tempfli, M.; Piraux, L.;

    2010-01-01

    Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide ri...

  10. Magnetic and superconducting nanowires

    DEFF Research Database (Denmark)

    Piraux, L.; Encinas, A.; Vila, L.;

    2005-01-01

    magnetic and superconducting nanowires. Using different approaches entailing measurements on both single wires and arrays, numerous interesting physical properties have been identified in relation to the nanoscopic dimensions of these materials. Finally, various novel applications of the nanowires are also...

  11. Chemically specific multiscale modeling of clay-polymer nanocomposites reveals intercalation dynamics, tactoid self-assembly and emergent materials properties.

    Science.gov (United States)

    Suter, James L; Groen, Derek; Coveney, Peter V

    2015-02-01

    A quantitative description is presented of the dynamical process of polymer intercalation into clay tactoids and the ensuing aggregation of polymer-entangled tactoids into larger structures, obtaining various characteristics of these nanocomposites, including clay-layer spacings, out-of-plane clay-sheet bending energies, X-ray diffractograms, and materials properties. This model of clay-polymer interactions is based on a three-level approach, which uses quantum mechanical and atomistic descriptions to derive a coarse-grained yet chemically specific representation that can resolve processes on hitherto inaccessible length and time scales. The approach is applied to study collections of clay mineral tactoids interacting with two synthetic polymers, poly(ethylene glycol) and poly(vinyl alcohol). The controlled behavior of layered materials in a polymer matrix is centrally important for many engineering and manufacturing applications. This approach opens up a route to computing the properties of complex soft materials based on knowledge of their chemical composition, molecular structure, and processing conditions. PMID:25488829

  12. Strip-Pattern-Spheres Self-Assembled from Polypeptide-Based Polymer Mixtures: Structure and Defect Features

    Science.gov (United States)

    Zhu, Xingyu; Guan, Zhou; Lin, Jiaping; Cai, Chunhua

    2016-07-01

    We found that poly(γ-benzyl-L-glutamate)-block-poly(ethylene glycol) (PBLG-b-PEG) rod-coil block copolymers and polystyrene (PS) homopolymers can cooperatively self-assemble into nano-spheres with striped patterns on their surfaces (strip-pattern-spheres) in aqueous solution. With assistance of dissipative particle dynamics simulation, it is discovered that the PS homopolymers form a spherical template core and the PBLG-b-PEG block copolymers assemble into striped patterns on the spherical surface. The hydrophobic PBLG rods are packed orderly in the strips, while the hydrophilic PEG blocks stabilize the strip-pattern-spheres in solution. Defects such as dislocations and disclinations can be observed in the striped patterns. Self-assembling temperature and sphere radius are found to affect defect densities in the striped patterns. A possible mechanism is proposed to illustrate how PBLG-b-PEG and PS cooperatively self-assemble into hierarchical spheres with striped patterns on surfaces.

  13. Self-limited plasmonic welding of silver nanowire junctions

    KAUST Repository

    Garnett, Erik C.

    2012-02-05

    Nanoscience provides many strategies to construct high-performance materials and devices, including solar cells, thermoelectrics, sensors, transistors, and transparent electrodes. Bottom-up fabrication facilitates large-scale chemical synthesis without the need for patterning and etching processes that waste material and create surface defects. However, assembly and contacting procedures still require further development. Here, we demonstrate a light-induced plasmonic nanowelding technique to assemble metallic nanowires into large interconnected networks. The small gaps that form naturally at nanowire junctions enable effective light concentration and heating at the point where the wires need to be joined together. The extreme sensitivity of the heating efficiency on the junction geometry causes the welding process to self-limit when a physical connection between the wires is made. The localized nature of the heating prevents damage to low-thermal-budget substrates such as plastics and polymer solar cells. This work opens new avenues to control light, heat and mass transport at the nanoscale. © 2012 Macmillan Publishers Limited. All rights reserved.

  14. Flexible Light-Emitting Diodes Based on Vertical Nitride Nanowires

    OpenAIRE

    Dai, Xing; Messanvi, Agnes; Zhang, Hezhi; Durand, Christophe; Eymery, Joël; Bougerol, Catherine; Julien, François H.; Tchernycheva, Maria

    2015-01-01

    International audience We demonstrate large area fully flexible blue LEDs based on core/shell InGaN/GaN nanowires grown by MOCVD. The fabrication relies on polymer encapsulation, nanowire lift-off and contacting using silver nanowire transparent electrodes. The LEDs exhibit rectifying behavior with a light-up voltage around 3 V. The devices show no electro-luminescence degradation neither under multiple bending down to 3 mm curvature radius nor in time for more than one month storage in am...

  15. Polymer Physics Prize Lecture: Self-assemblies of Giant Molecular Shape Amphiphiles as a New Platform for Engineering Structures with Sub-Nanometer Feature Sizes

    Science.gov (United States)

    Cheng, Stephen Z. D.

    2013-03-01

    Utilizing nano-building blocks rather than atoms to construct and engineer new structures is a fresh approach to design and develop functional materials for the purpose of transferring and amplifying microscopic functionality to macroscopic materials' property. As one of the important elements of these nano-building blocks, giant molecular shape amphiphiles (GMSAs) provide a latest platform for generating self-assembled ordered structures at nanometer scale, which are stabilized by collective physical bonds (such as collective hydrogen bonding). In this talk, two topics will be focused on. First, composed of functionalized hydrophilic molecular nanoparticles as the heads with rigid shape and fixed volume, and tethered polymer chains as the tails (such as giant molecular surfactants and lipids and other topologies), these GMSAs of various architectures can self-assemble into highly diversified, thermodynamically stable microstructures at sub-10 nm length scale in the bulk, thin film and solution states. Second, GMSAs could also be constructed solely from nanoparticles interconnected via different numbers of the rigid linkages in specific symmetry, simulating the overall shapes of small molecules but with sizes that are one-order of magnitude larger in length and three-order of magnitude larger in volume. Giant crystal structures can then be obtained from this class of ``giant molecules'' via supramolecular crystallization. These findings are not only scientifically intriguing in understanding the physical principles underlying their self-assembly, but also technologically relevant in industrial applications.

  16. Modeling and High-Resolution-Imaging Studies of Water-Content Profiles in a Polymer-Electrolyte-Fuel-Cell Membrane-Electrode Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Cynthia; Weber, A.Z.; Hickner, M.A.

    2008-03-06

    Water-content profiles across the membrane electrode assembly of a polymer-electrolyte fuel cell were measured using high-resolution neutron imaging and compared to mathematical-modeling predictions. It was found that the membrane held considerably more water than the other membrane-electrode constituents (catalyst layers, microporous layers, and macroporous gas-diffusion layers) at low temperatures, 40 and 60 C. The water content in the membrane and the assembly decreased drastically at 80 C where vapor transport and a heat-pipe effect began to dominate the water removal from the membrane-electrode assembly. In the regimes where vapor transport was significant, the through-plane water-content profile skewed towards the cathode. Similar trends were observed as the relative humidity of the inlet gases was lowered. This combined experimental and modeling approach has been beneficial in rationalizing the results of each and given insight into future directions for new experimental work and refinements to currently available models.

  17. From Self-Assembled Monolayers to Coatings: Advances in the Synthesis and Nanobio Applications of Polymer Brushes

    Directory of Open Access Journals (Sweden)

    Myungwoong Kim

    2015-07-01

    Full Text Available In this review, we describe the latest advances in synthesis, characterization, and applications of polymer brushes. Synthetic advances towards well-defined polymer brushes, which meet criteria such as: (i Efficient and fast grafting, (ii Applicability on a wide range of substrates; and (iii Precise control of surface initiator concentration and hence, chain density are discussed. On the characterization end advances in methods for the determination of relevant physical parameters such as surface initiator concentration and grafting density are discussed. The impact of these advances specifically in emerging fields of nano- and bio-technology where interfacial properties such as surface energies are controlled to create nanopatterned polymer brushes and their implications in mediating with biological systems is discussed.

  18. Super-Joule heating in graphene and silver nanowire network

    Energy Technology Data Exchange (ETDEWEB)

    Maize, Kerry [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Das, Suprem R.; Sadeque, Sajia; Mohammed, Amr M. S.; Shakouri, Ali, E-mail: shakouri@purdue.edu, E-mail: alam@purdue.edu; Janes, David B.; Alam, Muhammad A., E-mail: shakouri@purdue.edu, E-mail: alam@purdue.edu [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-04-06

    Transistors, sensors, and transparent conductors based on randomly assembled nanowire networks rely on multi-component percolation for unique and distinctive applications in flexible electronics, biochemical sensing, and solar cells. While conduction models for 1-D and 1-D/2-D networks have been developed, typically assuming linear electronic transport and self-heating, the model has not been validated by direct high-resolution characterization of coupled electronic pathways and thermal response. In this letter, we show the occurrence of nonlinear “super-Joule” self-heating at the transport bottlenecks in networks of silver nanowires and silver nanowire/single layer graphene hybrid using high resolution thermoreflectance (TR) imaging. TR images at the microscopic self-heating hotspots within nanowire network and nanowire/graphene hybrid network devices with submicron spatial resolution are used to infer electrical current pathways. The results encourage a fundamental reevaluation of transport models for network-based percolating conductors.

  19. Preparation of copper nano-wires by template synthesis method

    Institute of Scientific and Technical Information of China (English)

    郑国渠; 倪似愚; 郑华钧; 干学宏; 张九渊

    2004-01-01

    Highly ordered and porous anodic aluminum oxide templates were prepared. The ordered copper nanowires arrays were assembled in nano-holes of the template by alternating current electrodeposition at lower voltage.The morphologies of template and copper nano-wires arrays were characterized by means of field emission scanning electron microscope(FESEM) and the crystal structure of copper nano-wires was determined by means of X-ray diffraction. The results indicate that copper nano-wires hold the preferred crystalline orientation along (111), (200),(220) and (331) crystal faces during growth, and the growth of copper nano-wires in the nano-holes of the template is homogenous and continuous.

  20. Understanding of the self- and co-assembly behavior of recombinant protein polymers : from design to implementation

    NARCIS (Netherlands)

    Golinska, M.D.

    2014-01-01

    A key part of the growing field of biomedical sciences deals with the development of new, controlled and biocompatible biomaterials. In this thesis we present results on the design, production, purification and characterization of stimuli responsive protein polymers that could ultimately be used in

  1. Ambient Layer-by-Layer ZnO Assembly for Highly Efficient Polymer Bulk Heterojunction Solar Cells

    KAUST Repository

    Eita, Mohamed Samir

    2015-02-04

    The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in fl exible devices. Here, a layer-by-layer (LbL) protocol is reported as a facile, room-temperature, solution-processed method to prepare electron transport layers from commercial ZnO nanoparticles and polyacrylic acid (PAA) with a controlled and tunable porous structure, which provides large interfacial contacts with the active layer. Applying the LbL approach to bulk heterojunction polymer solar cells with an optimized ZnO layer thickness of H25 nm yields solar cell power-conversion effi ciencies (PCEs) of ≈6%, exceeding the effi ciency of amorphous ZnO interlayers formed by conventional sputtering methods. Interestingly, annealing the ZnO/PAA interlayers in nitrogen and air environments in the range of 60-300 ° C reduces the device PCEs by almost 20% to 50%, indicating the importance of conformational changes inherent to the PAA polymer in the LbL-deposited fi lms to solar cell performance. This protocol suggests a new fabrication method for solution-processed polymer solar cell devices that does not require postprocessing thermal annealing treatments and that is applicable to fl exible devices printed on plastic substrates.

  2. Self-assembly of carbon nanotubes in polymer melts: simulation of structural and electrical behaviour by hybrid particle-field molecular dynamics.

    Science.gov (United States)

    Zhao, Ying; Byshkin, Maksym; Cong, Yue; Kawakatsu, Toshihiro; Guadagno, Liberata; De Nicola, Antonio; Yu, Naisen; Milano, Giuseppe; Dong, Bin

    2016-08-25

    Self-assembly processes of carbon nanotubes (CNTs) dispersed in different polymer phases have been investigated using a hybrid particle-field molecular dynamics technique (MD-SCF). This efficient computational method allowed simulations of large-scale systems (up to ∼1 500 000 particles) of flexible rod-like particles in different matrices made of bead spring chains on the millisecond time scale. The equilibrium morphologies obtained for longer CNTs are in good agreement with those proposed by several experimental studies that hypothesized a two level "multiscale" organization of CNT assemblies. In addition, the electrical properties of the assembled structures have been calculated using a resistor network approach. The calculated behaviour of the conductivities for longer CNTs is consistent with the power laws obtained by numerous experiments. In particular, according to the interpretation established by the systematic studies of Bauhofer and Kovacs, systems close to "statistical percolation" show exponents t ∼ 2 for the power law dependence of the electrical conductivity on the CNT fraction, and systems in which the CNTs reach equilibrium aggregation show exponents t close to 1.7 ("kinetic percolation"). The confinement effects on the assembled structures and their corresponding conductivity behaviour in a non-homogeneous matrix, such as the phase separating block copolymer melt, have also been simulated using different starting configurations. The simulations reported herein contribute to a microscopic interpretation of the literature results, and the proposed modelling procedure may contribute meaningfully to the rational design of strategies aimed at optimizing nanomaterials for improved electrical properties.

  3. Size-dependent chemical transformation, structural phase-change, and optical properties of nanowires

    OpenAIRE

    Piccione, Brian; Agarwal, Rahul; Jung, Yeonwoong; Agarwal, Ritesh

    2013-01-01

    Nanowires offer a unique approach for the bottom up assembly of electronic and photonic devices with the potential of integrating photonics with existing technologies. The anisotropic geometry and mesoscopic length scales of nanowires also make them very interesting systems to study a variety of size-dependent phenomenon where finite size effects become important. We will discuss the intriguing size-dependent properties of nanowire systems with diameters in the 5 – 300 nm range, where finite ...

  4. Stability of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, F.; Schiek, M.; Wallmann, I.;

    2011-01-01

    The morphological stability of organic nanowires over time and under thermal load is of major importance for their use in any device. In this study the growth and stability of organic nanowires from a naphthyl end-capped thiophene grown by organic molecular beam deposition is investigated via...... atomic force microscopy (AFM). Aging experiments under ambient conditions already show substantial morphological changes. Nanoscopic organic clusters, which initially coexist with the nanowires, vanish within hours. Thermal annealing of nanowire samples leads to even more pronounced morphology changes......, such as a strong decrease in nanowire number density, a strong increase in nanowire height, and the formation of new types of crystallites. This happens even before sublimation of organic material starts. These experiments also shine new light on the formation process of the nanowires....

  5. Lattice cluster theory of associating polymers. II. Enthalpy and entropy of self-assembly and Flory-Huggins interaction parameter χ for solutions of telechelic molecules.

    Science.gov (United States)

    Dudowicz, Jacek; Freed, Karl F; Douglas, Jack F

    2012-02-14

    The lattice cluster theory for solutions of telechelic polymer chains, developed in paper I, is applied to determine the enthalpy Δh(p) and entropy Δs(p) of self-assembly of linear telechelics and to evaluate the Flory-Huggins (FH) interaction parameter χ governing the phase behavior of these systems. Particular focus is placed on examining how these interaction variables depend on the composition of the solution, temperature, van der Waals and local "sticky" interaction energies, and the length of the individual telechelic chains. The FH interaction parameter χ is found to exhibit an entropy-enthalpy compensation effect between the "entropic" and "enthalpic" portions as either the composition or mass of the telechelic species is varied, providing unique theoretical insights into this commonly reported, yet, enigmatic phenomenon.

  6. High-performance membrane-electrode assembly with an optimal polytetrafluoroethylene content for high-temperature polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung; Kim, Hyoung-Juhn; Shul, Yong-Gun; Cho, EunAe

    2016-08-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high-performance membrane-electrode assembly (MEA) with an optimal polytetrafluoroethylene (PTFE) content for HT-PEMFCs. Low or excess PTFE content in the electrode leads to an inefficient electrolyte distribution or severe catalyst agglomeration, respectively, which hinder the formation of triple phase boundaries in the electrodes and result in low performance. MEAs with PTFE content of 20 wt% have an optimal pore structure for the efficient formation of electrolyte/catalyst interfaces and gas channels, which leads to high cell performance of approximately 0.5 A cm-2 at 0.6 V.

  7. Three luminescent d10 metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu2+ ion and nitrobenzene

    International Nuclear Information System (INIS)

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL2]n (1) and ([ML2]·(H2O))n (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu2+ ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed. - Graphical abstract: Three luminescent d10 metal coordination polymers with helical-layer based on 4-((2-methyl-1H-imidazol-1-yl)methyl)benzoic acid have been obtained. Compound 1 shows high selective detecting for Cu2+ ion in aqueous and nitrobenzene. - Highlights: • Three coordination polymers with chiral helical-layer have been obtained. • 1 Can luminescent detect Cu2+ ion in aqueous media and nitrobenzene. • Racemic mixture or mesomer compounds can be obtained by controlling the reaction conditions

  8. Anion-controlled assembly of silver-di(aminophenyl)sulfone coordination polymers: Syntheses, crystal structures, and solid state luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qi-Long, E-mail: gzuqlzhang@126.com [Department of Chemistry, Guiyang Medical College, Guiyang 550004 (China); Hu, Peng [Department of Chemistry, Guiyang Medical College, Guiyang 550004 (China); Zhao, Yi [Key Laboratory of Macrocyclic and Supramolecular Chemistry, Guizhou University, Guiyang 550025 (China); Feng, Guang-Wei [Department of Chemistry, Guiyang Medical College, Guiyang 550004 (China); Zhang, Yun-Qian; Zhu, Bi-Xue; Tao, Zhu [Key Laboratory of Macrocyclic and Supramolecular Chemistry, Guizhou University, Guiyang 550025 (China)

    2014-02-15

    Five silver coordination polymers, namely, ([Ag(3,3′-daps){sub 2}]·BF{sub 4}){sub n} (1), ([Ag(3,3′-daps){sub 2}]·NO{sub 3}){sub n} (2), [Ag(3,3′-daps)(CF{sub 3}SO{sub 3})]{sub n} (3), ([Ag(4,4′-daps)]·CF{sub 3}SO{sub 3}){sub n} (4), and ([Ag(4,4′-daps)]·ClO{sub 4}){sub n} (5) (3,3′-daps=di(3′-aminodiphenyl)sulfone, and 4,4′-daps=di(4′-aminodiphenyl)sulfone) have been synthesized and structural characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analyses. Complex 1 displays a 1D ladder-like chain with four-connected Ag ions and bridged 3,3′-daps. Complex 2 shows other 1D ladder chain modified by tentacles. Complex 3 is a 2D layer structure with both Ag ions and 3,3′-daps are 3-connected nodes. Complex 4 is another 1D ladder chain with three-connected Ag ions and 4,4′-daps. Complex 5 shows a 2D 4{sup 4}-sql net with Ag ions and 4,4′-daps as 4-connected nodes. Moreover, their solid state luminescence and thermal stabilities also have been investigated. - Graphical abstract: Pictogram: Synthetic procedures of the five anion controlled silver coordination polymers. We reported the synthetic procedures, structure, and luminescence property of the five anion controlled silver coordination polymers based on two novel di(aminophenyl)sulfone V-shaped ligands. Display Omitted - Highlights: • Five new silver coordination polymers were synthesized and characterized. • Two novel designed V-shaped di(aminophenyl)sulfone ligands were first introduced to coordination chemistry. • Anions play important roles in determining the five silver coordination polymers. • The structural diversity and photoluminescence property were also discussed.

  9. A Self-Assembled Aggregate Composed of a Fatty Acid Membrane and the Building Blocks of Biological Polymers Provides a First Step in the Emergence of Protocells

    Science.gov (United States)

    Black, Roy A.; Blosser, Matthew C.

    2016-01-01

    We propose that the first step in the origin of cellular life on Earth was the self-assembly of fatty acids with the building blocks of RNA and protein, resulting in a stable aggregate. This scheme provides explanations for the selection and concentration of the prebiotic components of cells; the stabilization and growth of early membranes; the catalysis of biopolymer synthesis; and the co-localization of membranes, RNA and protein. In this article, we review the evidence and rationale for the formation of the proposed aggregate: (i) the well-established phenomenon of self-assembly of fatty acids to form vesicles; (ii) our published evidence that nucleobases and sugars bind to and stabilize such vesicles; and (iii) the reasons why amino acids likely do so as well. We then explain how the conformational constraints and altered chemical environment due to binding of the components to the membrane could facilitate the formation of nucleosides, oligonucleotides and peptides. We conclude by discussing how the resulting oligomers, even if short and random, could have increased vesicle stability and growth more than their building blocks did, and how competition among these vesicles could have led to longer polymers with complex functions. PMID:27529283

  10. Self-Assembly of Discrete Metallocycles versus Coordination Polymers Based on Cu(I and Ag(I Ions and Flexible Ligands: Structural Diversification and Luminescent Properties

    Directory of Open Access Journals (Sweden)

    Javier Vallejos

    2016-02-01

    Full Text Available Three new Ag(I and one Cu(I coordination compounds with two different positional isomers, propane-1,3-diyl bis(pyridine-4-carboxylate (L1 and propane-1,3-diyl bis(pyridine-3-carboxylate (L2, of a bis-(pyridyl-carboxylate ligand have been synthesized. X-ray diffraction analysis revealed that the self-assembly of L1 with AgCF3SO3 and AgClO4 salts leads to the formation of discrete binuclear metallocycles {Ag(L1CF3SO3}2 (1 and {Ag(L1ClO4}2 (2, respectively. However, self-assembly of the other ligand, L2, with AgCF3SO3 and CuCl salts, results in a 1-D zig-zag chain {Ag(L2CF3SO3}∞ (3 and a 1-D double-stranded helical chain {Cu2Cl2(L22}∞ (4 coordination polymers, respectively. Solid emission spectra recorded at room temperature show interesting luminescence properties for all four compounds in the range from 438 to 550 nm, especially for compound 4 that was found to change its emission color when the wavelength of the excitation radiation is switched from 332 to 436 nm.

  11. A Self-Assembled Aggregate Composed of a Fatty Acid Membrane and the Building Blocks of Biological Polymers Provides a First Step in the Emergence of Protocells.

    Science.gov (United States)

    Black, Roy A; Blosser, Matthew C

    2016-01-01

    We propose that the first step in the origin of cellular life on Earth was the self-assembly of fatty acids with the building blocks of RNA and protein, resulting in a stable aggregate. This scheme provides explanations for the selection and concentration of the prebiotic components of cells; the stabilization and growth of early membranes; the catalysis of biopolymer synthesis; and the co-localization of membranes, RNA and protein. In this article, we review the evidence and rationale for the formation of the proposed aggregate: (i) the well-established phenomenon of self-assembly of fatty acids to form vesicles; (ii) our published evidence that nucleobases and sugars bind to and stabilize such vesicles; and (iii) the reasons why amino acids likely do so as well. We then explain how the conformational constraints and altered chemical environment due to binding of the components to the membrane could facilitate the formation of nucleosides, oligonucleotides and peptides. We conclude by discussing how the resulting oligomers, even if short and random, could have increased vesicle stability and growth more than their building blocks did, and how competition among these vesicles could have led to longer polymers with complex functions. PMID:27529283

  12. Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c] pyrrole-4,6-dione polymers direct self-assembly and solar cell performance

    KAUST Repository

    Cabanetos, Clement

    2013-03-27

    While varying the size and branching of solubilizing side chains in π-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages of 0.97 V in BHJ devices with PC71BM, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells. © 2013 American Chemical Society.

  13. A novel method to synthesize cobalt oxide (Co3O4) nanowires from cobalt (Co) nanobowls

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A novel method suitable for the synthesis of the cobalt oxide (Co3O4) nanowires at targeted regions is presented in this report. Cobalt (Co) nanobowls synthesized by colloidal crystal directed assembly were transformed into Co3O4 nanowires by a simple heat treatment process. Co nanobowls exhibited...

  14. Controlling the Coupling of a Single Nitrogen Vacancy Center to a Silver Nanowire

    DEFF Research Database (Denmark)

    Huck, Alexander; Kumar, Shailesh; Shakoor, Abdul;

    2011-01-01

    -linear interaction at the level of a few photons. In our contribution we demonstrate the controlled coupling of a single nitrogen vacancy (NV) center in a diamond nano crystal to a nanowire made of silver. This is in contrast to previous realizations, where the nanowire dipole system was assembled randomly. Ultimate...

  15. Fe₃O₄@rGO doped molecularly imprinted polymer membrane based on magnetic field directed self-assembly for the determination of amaranth.

    Science.gov (United States)

    Han, Qing; Wang, Xi; Yang, Zaiyue; Zhu, Wanying; Zhou, Xuemin; Jiang, Huijun

    2014-06-01

    Based on magnetic field directed self-assembly (MDSA) of Fe3O4@rGO composites, a novel magnetic molecularly imprinted electrochemical sensor (MIES) was fabricated and developed for the determination of the azo dye amaranth. Fe3O4@rGO composites were obtained by a one-step approach involving the initial intercalating of iron ions between the graphene oxide layers via the electrostatic interaction, followed by the reduction with hydrazine hydrate to deposit Fe3O4 nanoparticles onto the reduced oxide graphene nanosheets. In molecular imprinting, the complex including the function monomer of aniline, the template of amaranth and Fe3O4@rGO was pre-assembled through π-π stacking and hydrogen bonding interactions, and then was self-assembled on the surface of magnetic glassy carbon electrode (MGCE) with the help of magnetic field induction before electropolymerization. The structures and morphologies of Fe3O4@rGO and the doped molecularly imprinted polymers (MIPs) were investigated by Fourier transform infrared spectrometer (FT-IR), Raman spectra and scanning electron microscope (SEM). Besides, the characterization by differential pulse voltammetry (DPV) showed that Fe3O4@rGO composites promoted the electrical conductivity of the imprinted sensors when doped into the MIPs. The adsorption isotherms and adsorption kinetics were employed to evaluate the performances of MIES. The detection of amaranth was achieved via the redox probe K3[Fe(CN)6] by blocking the imprinted cavities, which avoided the interferences of oxidation products and analogs of amaranth. Furthermore, the prepared MIES exhibited good sensitivity, selectivity, reproducibility and efficiency for detecting amaranth in fruit drinks. The average recoveries were 93.15-100.81% with the RSD <3.0%.

  16. Efficient Capture and Isolation of Tumor-Related Circulating Cell-Free DNA from Cancer Patients Using Electroactive Conducting Polymer Nanowire Platforms

    Science.gov (United States)

    Jeon, SeungHyun; Lee, HyungJae; Bae, Kieun; Yoon, Kyong-Ah; Lee, Eun Sook; Cho, Youngnam

    2016-01-01

    Circulating cell-free DNA (cfDNA) is currently recognized as a key non-invasive biomarker for cancer diagnosis and progression and therapeutic efficacy monitoring. Because cfDNA has been detected in patients with diverse types of cancers, the use of efficient strategies to isolate cfDNA not only provides valuable insights into tumour biology, but also offers the potential for developing new cancer-specific targets. However, the challenges associated with conventional cfDNA extraction methods prevent their further clinical applications. Here, we developed a nanostructured conductive polymer platform for the efficient capture and release of circulating cfDNA and demonstrated its potential clinical utility using unprocessed plasma samples from patients with breast and lung cancers. Our results confirmed that the platform's enhanced efficiency allows tumor-specific circulating cfDNA to be recovered at high yield and purity. PMID:27162553

  17. Surface self-assembled hybrid nanocomposites with electroactive nanoparticles and enzymes confined in a polymer matrix for controlled electrocatalysis

    DEFF Research Database (Denmark)

    Zhu, Nan; Ulstrup, Jens; Chi, Qijin

    2015-01-01

    the microscopic structures of the different layers during the surface architecture formation. The resulting surface-bound nanostructured composite shows high electrochemical activity arising from confined PBNPs, and acts as an efficient electrocatalyst towards H2O2 reduction. Facile electron communication...... is achieved as reflected by a large electron transfer (ET) rate constant (ks) of 200 s-1, and the possible electron propagation mechanisms in the polymer network are discussed. This surface/interfacial nanocomposite can be further used in the accommodation of enzymes for electrochemical bio-catalysis. Glucose...

  18. 3D Printing of Human Tissue Mimics via Layer-by-Layer Assembly of Polymer/Hydrogel Biopapers

    Science.gov (United States)

    Ringeisen, Bradley

    2015-03-01

    The foundations of tissue engineering were built on two fundamental areas of research: cells and scaffolds. Multipotent cells and their derivatives are traditionally randomly seeded into sophisticated polymer or hydrogel scaffolds, ultimately with the goal of forming a tissue-like material through cell differentiation and cell-material interactions. One problem with this approach is that no matter how complex or biomimetic the scaffold is, the cells are still homogeneously distributed throughout this three dimensional (3D) material. Natural tissue is inherently heterogeneous on both a microscopic and macroscopic level. It also contains different types of cells in close proximity, extracellular matrix, voids, and a complex vascularized network. Recently developed 3D cell and organ printers may be able to enhance traditional tissue engineering experiments by building scaffolds layer-by-layer that are crafted to mimic the microscopic and macroscopic structure of natural tissue or organs. Over the past decade, my laboratory has developed a capillary-free, live cell printer termed biological laser printing, or BioLP. We find that printed cells do not express heat shock protein and retain >99% viability. Printed cells also incur no DNA strand fracture and preserve their ability to differentiate. Recent work has used a layer-by-layer approach, stacking sheets of hybrid polymer/hydrogel biopapers in conjunction with live cell printing to create 3D tissue structures. Our specific work is now focused on the blood-brain-barrier and air-lung interface and will be described during the presentation.

  19. Nanotubes and nanowires

    Indian Academy of Sciences (India)

    C N R Rao; A Govindaraj

    2001-10-01

    Synthesis and characterization of nanotubes and nanowires constitute an important part of nanoscience since these materials are essential bui lding units for several devices. We have prepared aligned carbon nanotube bundles and Y-junction nanotubes by the pyrolysis of appropriate organic precursors. The aligned bundles are useful for field emission display while the Y-junction nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have be en obt a ined. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with the aspect ratio. GaN nanowires show excellent photoluminescence characteristics. It has been possible to synthesise nanotubes and nanowires of metal chalcogenides by employing different strategies.

  20. Variation in electrical properties of gamma irradiated cadmium selenate nanowires

    Science.gov (United States)

    Chauhan, R. P.; Rana, Pallavi; Narula, Chetna; Panchal, Suresh; Choudhary, Ritika

    2016-07-01

    Preparation of low-dimensional materials attracts more and more interest in the last few years, mainly due to the wide field of potential commercial applications ranging from life sciences, medicine and biotechnology to communication and electronics. One-dimensional systems are the smallest dimension structures that can be used for efficient transport of electrons and thus expected to be critical to the function and integration of nanoscale devices. Nanowires with well controlled morphology and extremely high aspect ratio can be obtained by replicating a nanoporous polymer ion-track membrane with cylindrical pores of controlled dimensions. With this technique, materials can be deposited within the pores of the membrane by electrochemical reduction of the desired ion. In the present study, cadmium selenate nanowires were synthesized potentiostatically via template method. These synthesized nanowires were then exposed to gamma rays by using a 60Co source at the Inter University Accelerator Centre, New Delhi, India. Structural, morphological, electrical and elemental characterizations were made in order to analyze the effect of gamma irradiation on the synthesized nanowires. I-V measurements of cadmium selenate nanowires, before and after irradiation were made with the help of Keithley 2400 source meter and Ecopia probe station. A significant change in the electrical conductivity of cadmium selenate nanowires was found after gamma irradiation. The crystallography of the synthesized nanowires was also studied using a Rigaku X-ray diffractrometer equipped with Cu-Kα radiation. XRD patterns of irradiated samples showed no variation in the peak positions or phase change.

  1. Polymer-based photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edrington, A.C.; Urbas, A.M.; Fink, Y.; Thomas, E.L. [Massachusetts Inst. of Tech., Cambridge (United States). Dept. of Materials Science and Engineering; DeRege, P. [Firmenich, Inc., Port Newark, NJ (United States); Chen, C.X.; Swager, T.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry; Hadjichristidis, N. [Athens Univ. (Greece). Dept. of Chemistry; Xenidou, M.; Fetters, L.J. [ExxonMobil Research Corp., Annandale, NJ (United States); Joannopoulos, J.D. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics

    2001-03-16

    The development of polymers as photonic crystals is highlighted, placing special emphasis on self-assembled block copolymers. 1D self-assembled multilayers as well as 2D and 3D self-assembled structures are examined, then intricate block polymer structures such as that shown in the Figure are discussed as are birefringent multilayer and elastomeric films. (orig.)

  2. Optical fibre nanowire devices

    OpenAIRE

    Xu, Fei

    2008-01-01

    The Optical Fibre Nanowire (OFN) is a potential building block in future micro- and nano-photonic device since it offers a number of unique optical and mechanical properties. In this thesis, the background and fundamental features of nanowires are introduced; the theory, design and demonstration of novel nanowire devices are discussed. At first, a short adiabatic taper tip is manufactured, and it is used as optical tweezers for trapping 1?m microspheres. Then, the most important devic...

  3. Coupling of a single quantum emitter to end-to-end aligned silver nanowires

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Chen, Yuntian;

    2013-01-01

    We report on the observation of coupling a single nitrogen vacancy (NV) center in a nanodiamond crystal to a propagating plasmonic mode of silver nanowires. The nanocrystal is placed either near the apex of a single silver nanowire or in the gap between two end-to-end aligned silver nanowires. We...... observe an enhancement of the NV-centers' decay rate in both cases as a result of the coupling to the plasmons. The devices are nano-assembled with a scanning probe technique. Through simulations, we show that end-to-end aligned silver nanowires can be used as a controllable splitter for emission from...

  4. Gas adsorption/separation properties of metal directed self-assembly of two coordination polymers with 5-nitroisophthalate

    Energy Technology Data Exchange (ETDEWEB)

    Arıcı, Mürsel [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Yeşilel, Okan Zafer, E-mail: yesilel@ogu.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Keskin, Seda [Department of Chemical and Biological Engineering, Koç University, İstanbul (Turkey); Şahin, Onur [Scientific and Technological Research Application and Research Center, Sinop University, 57010 Sinop (Turkey)

    2014-02-15

    Two new coordination polymers, namely, [Co(µ-nip)(µ-bpe)]{sub n} (1) and [Zn(µ-nip)(µ-bpe)]{sub n} (2) (nip: 5-nitroisophthalate, bpe: 1,2-bis(4-pyridyl)ethane) were hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermal analysis. Moreover, atomically detailed simulation studies of complex 2 for CO{sub 2}/CH{sub 4} adsorption and separation were performed. Complex 1 consists of two dimensional (2D) (4,4) grid networks with the point symbol of 4{sup 4}.6{sup 2}. Complex 2 exhibits a 3-fold interpenetrating 3D framework with 6{sup 5}.8-dmp topology. Thermal properties of the complexes showed that both complexes were stable over 320 °C. Simulation studies demonstrated that complex 2 can separate CO{sub 2} from CH{sub 4} at low pressures at 273 K. - Graphical abstract: In this study, two new coordination polymers, namely, [Co(µ-nip)(µ-bpe)]{sub n} (1) and [Zn(µ-nip)(µ-bpe)]{sub n} (2) (nip: 5-nitroisophthalate, bpe: 1,2-bis(4-pyridyl)ethane) were hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermal analysis. Moreover, atomically detailed simulation studies of complex 2 for CO{sub 2}/CH{sub 4} adsorption and separation were performed. Complex 1 consists of two dimensional (2D) (4,4) grid networks with the point symbol of 4{sup 4}.6{sup 2}. Complex 2 exhibits a 3-fold interpenetrating 3D framework with 6{sup 5}.8-dmp topology. Simulation studies demonstrated that complex 2 can separate CO{sub 2} from CH{sub 4} at low pressures at 273 K. Display Omitted - Highlights: • Two new coordination polymers with 5-nitroisophthalate and 1,2-bis(4-pyridyl)ethane. • Atomically detailed simulation studies of the complexes. • Complex 2 can be proposed as molecular sieve to separate CO{sub 2} from CH{sub 4} at low pressures.

  5. Characterization of stable, electroactive protein cage/synthetic polymer multilayer thin films prepared by layer-by-layer assembly

    Energy Technology Data Exchange (ETDEWEB)

    Uto, Koichiro [National Institute for Materials Science (NIMS), Biomaterials Unit, International Research Center for Materials Nanoarchitectonics (WPI-MANA) (Japan); Yamamoto, Kazuya [Graduate School of Science and Engineering, Kagoshima University, Department of Nanostructure and Advanced Materials (Japan); Kishimoto, Naoko [CREST, Japan Science and Technology Agency (Japan); Muraoka, Masahiro [Osaka Institute of Technology, Department of Applied Chemistry, Faculty of Engineering (Japan); Aoyagi, Takao, E-mail: aoyagi.takao@nims.go.jp [National Institute for Materials Science (NIMS), Biomaterials Unit, International Research Center for Materials Nanoarchitectonics (WPI-MANA) (Japan); Yamashita, Ichiro, E-mail: ichiro@ms.naist.jp [CREST, Japan Science and Technology Agency (Japan)

    2013-04-15

    We have fabricated electroactive multilayer thin films containing ferritin protein cages. The multilayer thin films were prepared on a solid substrate by the alternate electrostatic adsorption of (apo)ferritin and poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (NIPAAm-co-CIPAAm) in pH 3.5 acetate buffer solution. The assembly process was monitored using a quartz crystal microbalance. The (apo)ferritin/poly(NIPAAm-co-CIPAAm) multilayer thin films were then cross-linked using a water-soluble carbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The cross-linked films were stable under a variety of conditions. The surface morphology and thickness of the multilayer thin films were characterized by atomic force microscopy, and the ferritin iron cores were observed by scanning electron microscopy to confirm the assembly mechanism. Cyclic voltammetry measurements showed different electrochemical properties for the cross-linked ferritin and apoferritin multilayer thin films, and the effect of stability of the multilayer film on its electrochemical properties was also examined. Our method for constructing multilayer films containing protein cages is expected to be useful in building more complex functional inorganic nanostructures.

  6. Characterization of stable, electroactive protein cage/synthetic polymer multilayer thin films prepared by layer-by-layer assembly

    International Nuclear Information System (INIS)

    We have fabricated electroactive multilayer thin films containing ferritin protein cages. The multilayer thin films were prepared on a solid substrate by the alternate electrostatic adsorption of (apo)ferritin and poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (NIPAAm-co-CIPAAm) in pH 3.5 acetate buffer solution. The assembly process was monitored using a quartz crystal microbalance. The (apo)ferritin/poly(NIPAAm-co-CIPAAm) multilayer thin films were then cross-linked using a water-soluble carbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The cross-linked films were stable under a variety of conditions. The surface morphology and thickness of the multilayer thin films were characterized by atomic force microscopy, and the ferritin iron cores were observed by scanning electron microscopy to confirm the assembly mechanism. Cyclic voltammetry measurements showed different electrochemical properties for the cross-linked ferritin and apoferritin multilayer thin films, and the effect of stability of the multilayer film on its electrochemical properties was also examined. Our method for constructing multilayer films containing protein cages is expected to be useful in building more complex functional inorganic nanostructures.

  7. Growth model of lantern-like amorphous silicon oxide nanowires

    Science.gov (United States)

    Wu, Ping; Zou, Xingquan; Chi, Lingfei; Li, Qiang; Xiao, Tan

    2007-03-01

    Silicon oxide nanowire assemblies with lantern-like morphology were synthesized by thermal evaporation of the mixed powder of SnO2 and active carbon at 1000 °C and using the silicon wafer as substrate and source. The nano-lanterns were characterized by a scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), energy-dispersive spectroscope (EDS) and selective area electron diffraction (SAED). The results show that the nano-lantern has symmetrical morphology, with one end connecting with the silicon wafer and the other end being the tin ball. The diameter of the nano-lantern is about 1.5-3.0 µm. Arc silicon oxide nanowire assemblies between the two ends have diameters ranging from 70 to 150 nm. One single catalyst tin ball catalyzes more than one amorphous nanowires' growth. In addition, the growth mechanism of the nano-lantern is discussed and a growth model is proposed. The multi-nucleation sites round the Sn droplet's perimeter are responsible for the formation of many SiOx nanowires. The growing direction of the nanowires is not in the same direction of the movement of the catalyst tin ball, resulting in the bending of the nanowires and forming the lantern-like silicon oxide morphology. The controllable synthesis of the lantern-like silicon oxide nanostructure may have potential applications in the photoelectronic devices field.

  8. Growth model of lantern-like amorphous silicon oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ping; Zou Xingquan; Chi Lingfei; Li Qiang; Xiao Tan [Department of Physics, Shantou University, Shantou 515063 (China)

    2007-03-28

    Silicon oxide nanowire assemblies with lantern-like morphology were synthesized by thermal evaporation of the mixed powder of SnO{sub 2} and active carbon at 1000 deg. C and using the silicon wafer as substrate and source. The nano-lanterns were characterized by a scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), energy-dispersive spectroscope (EDS) and selective area electron diffraction (SAED). The results show that the nano-lantern has symmetrical morphology, with one end connecting with the silicon wafer and the other end being the tin ball. The diameter of the nano-lantern is about 1.5-3.0 {mu}m. Arc silicon oxide nanowire assemblies between the two ends have diameters ranging from 70 to 150 nm. One single catalyst tin ball catalyzes more than one amorphous nanowires' growth. In addition, the growth mechanism of the nano-lantern is discussed and a growth model is proposed. The multi-nucleation sites round the Sn droplet's perimeter are responsible for the formation of many SiO{sub x} nanowires. The growing direction of the nanowires is not in the same direction of the movement of the catalyst tin ball, resulting in the bending of the nanowires and forming the lantern-like silicon oxide morphology. The controllable synthesis of the lantern-like silicon oxide nanostructure may have potential applications in the photoelectronic devices field.

  9. Surface-controlled contact printing for nanowire device fabrication on a large scale

    Science.gov (United States)

    Roßkopf, D.; Strehle, S.

    2016-05-01

    Assembly strategies for functional nanowire devices that merge bottom-up and top-down technologies have been debated for over a decade. Although several breakthroughs have been reported, nanowire device fabrication techniques remain generally incompatible with large-scale and high-yield top-down microelectronics manufacturing. Strategies enabling the controlled transfer of nanowires from the growth substrate to pre-defined locations on a target surface would help to address this challenge. Based on the promising concept of mechanical nanowire transfer, we developed the technique of surface-controlled contact printing, which is based purely on dry friction between a nanowire and a target surface. Surface features, so-called catchers, alter the local frictional force or deposition probability and allow the positioning of single nanowires. Surface-controlled contact printing extends the current scope of nanowire alignment strategies with the intention to facilitate efficient nanowire device fabrication. This is demonstrated by the simultaneous assembly of 36 nanowire resistors within a chip area of greater than 2 cm2 aided only by mask-assisted photolithography.

  10. Assembly, crystal structure, and luminescent properties of three-dimensional (10,3)-a netted rare earth coordination polymers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Solid complexes [REL(NO3)3]n with novel (10,3)-a type three-dimensional networks structure have been assembled using rare earth nitrates and an amide type semirigid tripodal bridging ligand, 1,3,5-tris {[(2′-benzylaminoformyl)phenoxyl]methyl}benzene (L), as building blocks. The complexes were crys- tallized in the orthorhombic system with chiral space group P212121. The whole structure consists of an infinite array of trigonal RE(III) ions bridged by tridentate ligands, and a novel (10,3)-a net is formed, which is very uncommon in the rare earth complexes. At room temperature, the Sm(III), Eu(III), Tb(III), Dy(III) complexes all exhibited characteristic luminescence emissions of central metal ions under UV light excitation.

  11. Fabrication and characterization of polymer/nanoclay hybrid ultrathin multilayer film by spin self-assembly method

    International Nuclear Information System (INIS)

    We have prepared ultrathin multilayer nanostructural films by a layer-by-layer spin self-assembly method using poly (p-phenylene vinylene) (PPV)/layered silicate and characterized them by contact angle measurement, surface dying technique, UV/Vis spectroscopy, photoluminescent (PL) spectroscopy, X-ray reflectivity (XRR), and model-fitting. The hybrid ultrathin multilayer film was stepwisely deposited using the electrostatic forces between the cationic PPV precursor and the negatively charged surface of layered silicate, and finally thermally converted to (PPV/Laponite RD)n film. The surface coverage of the PPV precursor onto layered silicate and vice versa could be clearly observed using the contact angle measurement and surface dying technique. The continuous increase of UV/Vis absorbance and PL intensity of the films with each bilayer demonstrated the regular and reproducible deposition of this system, and the Kiessig fringes and Bragg peaks in XRR spectra indicated the well-ordered internal structure

  12. Light-triggered self-construction of supramolecular organic nanowires as metallic interconnects

    Science.gov (United States)

    Faramarzi, Vina; Niess, Frédéric; Moulin, Emilie; Maaloum, Mounir; Dayen, Jean-François; Beaufrand, Jean-Baptiste; Zanettini, Silvia; Doudin, Bernard; Giuseppone, Nicolas

    2012-06-01

    The construction of soft and processable organic material able to display metallic conduction properties—a large density of freely moving charges—is a major challenge for electronics. Films of doped conjugated polymers are widely used as semiconductor devices, but metallic-type transport in the bulk of such materials remains extremely rare. On the other hand, single-walled carbon nanotubes can exhibit remarkably low contact resistances with related large currents, but are intrinsically very difficult to isolate and process. Here, we describe the self-assembly of supramolecular organic nanowires between two metallic electrodes, from a solution of triarylamine derivative, under the simultaneous action of light and electric field triggers. They exhibit a combination of large conductivity values (>5 × 103 S m-1) and a low interface resistance (<2 × 10-4 Ω m). Moreover, the resistance of nanowires in series with metal interfaces systematically decreases when the temperature is lowered to 1.5 K, revealing an intrinsic metallic behaviour.

  13. Controlling nanowire growth through electric field-induced deformation of the catalyst droplet

    Science.gov (United States)

    Panciera, Federico; Norton, Michael M.; Alam, Sardar B.; Hofmann, Stephan; Mølhave, Kristian; Ross, Frances M.

    2016-07-01

    Semiconductor nanowires with precisely controlled structure, and hence well-defined electronic and optical properties, can be grown by self-assembly using the vapour-liquid-solid process. The structure and chemical composition of the growing nanowire is typically determined by global parameters such as source gas pressure, gas composition and growth temperature. Here we describe a more local approach to the control of nanowire structure. We apply an electric field during growth to control nanowire diameter and growth direction. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet. This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and also to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth.

  14. Nanowire LEDs grown directly on flexible metal foil

    Science.gov (United States)

    May, Brelon J.; Sarwar, A. T. M. Golam; Myers, Roberto C.

    2016-04-01

    Using molecular beam epitaxy, self-assembled AlGaN nanowires are grown directly on Ta and Ti foils. Scanning electron microscopy shows that the nanowires are locally textured with the underlying metallic grains. Photoluminescence spectra of GaN nanowires grown on metal foils are comparable to GaN nanowires grown on single crystal Si wafers. Similarly, photoluminescence lifetimes do not vary significantly between these samples. Operational AlGaN light emitting diodes are grown directly on flexible Ta foil with an electroluminescence peak emission of ˜350 nm and a turn-on voltage of ˜5 V. These results pave the way for roll-to-roll manufacturing of solid state optoelectronics.

  15. Research and Application of Polymer Nanofibers

    Institute of Scientific and Technical Information of China (English)

    张兴祥; 陶肖明; 樊耀峰

    2003-01-01

    Nanometer materials include roughly nanoparticle,nanotube, nanowire, nanofiber, nanofilm and nanoblock, among which nanofiber is defined as material with nanometer-sized diameter and longer than 1 micron in length. The research development of polymer nanofibers, including manufacture methods and properties of some polymer nanofibers as well as their potential applications is reviewed.

  16. Facile and controllable one-step fabrication of molecularly imprinted polymer membrane by magnetic field directed self-assembly for electrochemical sensing of glutathione

    International Nuclear Information System (INIS)

    Based on magnetic field directed self-assembly (MDSA) of the ternary Fe3O4@PANI/rGO nanocomposites, a facile and controllable molecularly imprinted electrochemical sensor (MIES) was fabricated through a one-step approach for detection of glutathione (GSH). The ternary Fe3O4@PANI/rGO nanocomposites were obtained by chemical oxidative polymerization and intercalation of Fe3O4@PANI into the graphene oxide layers via π–π stacking interaction, followed by reduction of graphene oxide in the presence of hydrazine hydrate. In molecular imprinting process, the pre-polymers, including GSH as template molecule, Fe3O4@PANI/rGO nanocomposites as functional monomers and pyrrole as both cross-linker and co-monomer, was assembled through N–H hydrogen bonds and the electrostatic interaction, and then was rapidly oriented onto the surface of MGCE under the magnetic field induction. Subsequently, the electrochemical GSH sensor was formed by electropolymerization. In this work, the ternary Fe3O4@PANI/rGO nanocomposites could not only provide available functionalized sites in the matrix to form hydrogen bond and electrostatic interaction with GSH, but also afford a promoting network for electron transfer. Moreover, the biomimetic sensing membrane could be controlled more conveniently and effectively by adjusting the magnetic field strength. The as-prepared controllable sensor showed good stability and reproducibility for the determination of GSH with the detection limit reaching 3 nmol L−1 (S/N = 3). In addition, the highly sensitive and selective biomimetic sensor has been successfully used for the clinical determination of GSH in biological samples. - Highlights: • The ternary composites exhibited great conductivity and electrocatalytical activity. • By magnetic field induction, the orderly film was fabricated on the surface of MGCE. • The microstructure of the sensing membrane could be controlled more conveniently. • The sensor was applied for rapid and direct

  17. Amplified fluorescence detection of adenosine via catalyzed hairpin assembly and host-guest interactions between β-cyclodextrin polymer and pyrene.

    Science.gov (United States)

    Huang, Haihua; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Guo, Qiuping; Huang, Jin; Liu, Jianbo; Song, Chunxia

    2016-04-21

    Nowadays, enzyme-free nucleic acid-based signal amplification strategies are frequently utilized in the design of biosensors due to their excellent sensitivity. Developing more extended analytical methods is fundamental for basic studies in the biological and biomedical fields. Herein, we introduce an enzyme-free amplified detection strategy for the small molecule adenosine. The approach is based on adenosine-aptamer binding triggered catalyzed hairpin assembly and host-guest interactions between β-cyclodextrin polymer (β-CDP) and pyrene. Two hairpin probes (probe H1 and probe H2) and an aptamer-trigger/inhibitor duplex probe were employed in the system and the pyrene-labeled probe H1 was chosen as the signal unit. In the absence of adenosine, the aptamer-trigger was inhibited by the inhibitor strand. The hairpin probes were in the closed hairpin formation without activation of the trigger strand. Pyrene labeled at the 5'-termini of the single-stranded stem of probe H1 could be easily trapped in the hydrophobic cavity of β-CDP because of weak steric hindrance, leading to a significant fluorescence enhancement. Once the hairpin assembly was catalyzed by the adenosine-aptamer binding event, a hybridized DNA duplex H1/H2 was created continuously. Pyrene labeled at the 5'-termini of the DNA duplex H1/H2 finds it difficult to enter the cavity of β-CDP due to steric hindrance, leading to a weaker fluorescence signal. Thus, the target could be detected by this simple mix-and-detect amplification method without a need for expensive and perishable protein enzymes. As low as 42 nM of adenosine was detected by this assay, which is comparable to that of some reported colorimetric methods. Meanwhile, the proposed method was further successfully applied to detect adenosine in human serum samples, showing great potential for adenosine detection from complex fluids.

  18. Control of photon transport properties in nanocomposite nanowires

    OpenAIRE

    Moffa, M.; Fasano, V.; A. Camposeo; Persano, L; D. Pisignano

    2016-01-01

    Active nanowires and nanofibers can be realized by the electric-field induced stretching of polymer solutions with sufficient molecular entanglements. The resulting nanomaterials are attracting an increasing attention in view of their application in a wide variety of fields, including optoelectronics, photonics, energy harvesting, nanoelectronics, and microelectromechanical systems. Realizing nanocomposite nanofibers is especially interesting in this respect. In particular, methods suitable f...

  19. Assembly and Crystal Structure of a Novel 1-D Coordination Polymer of Copper(Ⅱ) with Thiocyanate and 4-Cyanopyridine

    Institute of Scientific and Technical Information of China (English)

    LI,Xiu-Yan(李秀艳); WANG,Ping(王平); WANG,Zhe-Ming(王哲明); YAN,Chun-Hua(严纯华); ZHANG,Li-Dan(张丽丹); GUO,Hong-You(郭洪猷)

    2002-01-01

    A novel one-dimensional coordination polymer, Catena-poly [bis(4-cyano-pyridyl) copper(Ⅱ)-di-thiocyanate ], 1∞[CuⅡ-(cypy)2(μN,s-SCN)2] (cypy=4-cyano-pyridyl), was synthe sized in a solution reaction of Cu(NO3)2@3H2O, 4-cyano-pyri dine and KSCN in mole ratio of 1:2:2 at room temperature.Its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic crystal system,space group P21/c with cell parameters a = 1.0719(2), b =1.8441(4), c =0.9144(2) nm, β= 110.49(3)° and Z=4. Afull-matrix least-squares refinement gave Ri = 0. 0393 and wR2 = 0. 0916 for 1554 reflections having Ⅰ> 2σ (Ⅰ). The crystal is thermally stable up to approximately 170 ℃.

  20. Secondary ligand-directed assembly of Co(II) coordination polymers based on a pyridine carboxylate ligand

    Science.gov (United States)

    Cao, Ke-Li; Zhang, Yi-Ping; Cai, Yi-Ni; Xu, Xiao-Wei; Feng, Yun-Long

    2014-07-01

    To investigate the influence of hydrogen bonds and secondary ligands on the structures and properties of the resulting frameworks, five new Co(II) compounds have been synthesized by the reactions of Co(II) salts and 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL) with four rationally selected dicarboxylic acid ligands. Without secondary ligand, we got one compound [CoL2(H2O)2]n·2nH2O (1), which possesses a 1D chain structure. In the presence of ancillary ligands, namely, 1,3-adamantanedicarboxylic acid (H2adbc), terephthalic acid (H2tpa), thiophene-2,5-dicarboxylic acid (H2tdc) and 1,4-benzenedithioacetic acid (H2bdtc), four 3D structures [Co2L2(adbc)]n·nH2O (2), [Co2L2(tpa)]n (3), [Co2L2(tdc)]n (4), [Co2L2(bdtc)(H2O)]n (5) were obtained, respectively. It can be observed from the architectures of 1-5 that hydrogen bonds and secondary ligands both have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. The XRPD, TGA data of title polymers and the magnetic properties for 2 and 5 have also been investigated.

  1. Formation of fractals by the self-assembly of interpolymer adducts of polymethacrylic acid with complementary polymers in aqueous solution

    Indian Academy of Sciences (India)

    Kandhasamy Durai Murugan; Arlin Jose Amali; Paramasivam Natarajan

    2012-03-01

    Interpolymer adducts of poly(methacrylic acid), (PMAA), with poly(vinylpyrrolidone) in presence of sodium chloride or potassium chloride form highly ordered fractal patterns in films on glass surface on drying at ambient temperature. The structure, morphology and the conditions under which the formation of fractal patterns occurs were investigated by SEM, EDX and confocal microscopic techniques. Self-organization of PMAA with complementary polymers such as poly(vinylpyrrolidone) is well-known and in the presence of sodium chloride formation of the fractals in films of the adducts is a novel observation. Fractal formation occurs due to the aggregation of interpolymer adducts. The composition of the fractals in the film is studied by EDX and confocal microscopic images of the fluorophores covalently bound to PMAA. In presence of salts, sodium chloride or potassium chloride, micellar like entities of 80 nm size were formed which further aggregate to form fractal patterns. It is suggested that the fractals result from the interpolymer adduct by Diffusion Limited Aggregation mechanism.

  2. Assembly of three new POM-based Ag(I) coordination polymers with antibacterial and photocatalytic properties

    Science.gov (United States)

    Lu, Xin-Xin; Luo, Yu-Hui; Lu, Chen; Chen, Xin; Zhang, Hong

    2015-12-01

    Three new silver coordination polymers, namely, {Ag3(bpy)6[PW12O40]} (1), {Ag5(H2biim)2(Hbiim-NO2)2[PW12O40]} (2), {Ag7(pytz)4[PW12O40]} (3) (bpy=2,2‧-bipyridine, H2biim=2,2‧-biimidazole, pytz=4-(1H-tetrazol-5-yl)pyridine), have been synthesized under hydrothermal condition. Compound 1 shows a 3D supramolecular framework based on 0D moieties. Compound 2 exhibits an attractive 2D biologic screw axis. Compound 3 displays a 3D structure, which consists of Ag(I)···π interactions, π···π stacking and weak Ag···Ag interactions. It is noteworthy that nitration happens to compound 2 during the hydrothermal condition, which is quite rare. Through contrasting the antibacterial activities of gram negative and gram positive bacteria, we find compounds 1-3 have better antibacterial property in gram negative bacteria than gram positive bacteria. In addition, compounds 1-3 also exhibit efficiency of photocatalytic decomposition of organic dyes. Those compounds may be used as potential multifunctional materials in wastewater treatment, because they not only can kill bacteria but also degrade organic pollutants.

  3. Nanowire Photovoltaic Devices

    Science.gov (United States)

    Forbes, David

    2015-01-01

    Firefly Technologies, in collaboration with the Rochester Institute of Technology and the University of Wisconsin-Madison, developed synthesis methods for highly strained nanowires. Two synthesis routes resulted in successful nanowire epitaxy: direct nucleation and growth on the substrate and a novel selective-epitaxy route based on nanolithography using diblock copolymers. The indium-arsenide (InAs) nanowires are implemented in situ within the epitaxy environment-a significant innovation relative to conventional semiconductor nanowire generation using ex situ gold nanoparticles. The introduction of these nanoscale features may enable an intermediate band solar cell while simultaneously increasing the effective absorption volume that can otherwise limit short-circuit current generated by thin quantized layers. The use of nanowires for photovoltaics decouples the absorption process from the current extraction process by virtue of the high aspect ratio. While no functional solar cells resulted from this effort, considerable fundamental understanding of the nanowire epitaxy kinetics and nanopatterning process was developed. This approach could, in principle, be an enabling technology for heterointegration of dissimilar materials. The technology also is applicable to virtual substrates. Incorporating nanowires onto a recrystallized germanium/metal foil substrate would potentially solve the problem of grain boundary shunting of generated carriers by restricting the cross-sectional area of the nanowire (tens of nanometers in diameter) to sizes smaller than the recrystallized grains (0.5 to 1 micron(exp 2).

  4. Metallic nanowire networks

    Science.gov (United States)

    Song, Yujiang; Shelnutt, John A.

    2012-11-06

    A metallic nanowire network synthesized using chemical reduction of a metal ion source by a reducing agent in the presence of a soft template comprising a tubular inverse micellar network. The network of interconnected polycrystalline nanowires has a very high surface-area/volume ratio, which makes it highly suitable for use in catalytic applications.

  5. The fabrication and enhanced nonlinear optical properties of electrostatic self-assembled film containing water-soluble chiral polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Qiuyun, E-mail: qyouyang7823@yahoo.cn [College of Science, Harbin Engineering University, Harbin 150001 (China); Chen Yujin; Li Chunyan [College of Science, Harbin Engineering University, Harbin 150001 (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin film containing the chiral PPV and oligo-thiophene derivatives was fabricated. Black-Right-Pointing-Pointer The third-order NLO properties were studied of the ultra-thin film. Black-Right-Pointing-Pointer The reverse saturable absorption and self-defocusing were observed. Black-Right-Pointing-Pointer The nonlinear optical mechanism was discussed. - Abstract: An ultra-thin film containing a water-soluble chiral PPV derivative and oligo-thiophene derivative was fabricated through the electrostatic self-assembly technique. The PPV and thiophene derivatives are poly{l_brace}(2,5-bis(3-bromotrimethylammoniopropoxy)-phenylene-1,4-divinylene) -alt-1,4-(2,5-bis((3-hydroxy-2-(S)-methyl)propoxy)phenylenevinylene) (BHP-PPV) and 4 Prime ,3 Double-Prime -dipentyl-5,2 Prime :5 Prime ,2 Double-Prime :5 Double-Prime ,2 Double-Prime Prime -quaterthiophene-2,5 Double-Prime Prime -dicarboxylic acid (QTDA), respectively. The circular dichroism (CD) spectrum of BHP-PPV cast film on quartz substrate proved the chirality of BHP-PPV. The UV-vis spectra showed a continuous deposition process of BHP-PPV and QTDA. The film structure was characterized by small angle X-ray diffraction (XRD) measurement and atomic force microscopy (AFM) images. The nonlinear optical (NLO) properties of BHP-PPV/QTDA ultra-thin film with different number of bilayers were investigated by the Z-scan technique with 8 ns laser pulse at 532 nm. The Z-scan experimental data were analyzed with the double-sided film Z-scan theory. The BHP-PPV/QTDA film exhibits enhanced reverse saturable absorption (RSA) and self-defocusing effects, which may be attributed to the conjugated strength, chirality and well-ordered film structure. The chirality may lead to the RSA of BHP-PPV/QTDA film contrary to the SA of the other electrostatic self-assembled films without chiral units. The self-defocusing effect should be due to the thermal effect.

  6. Self-assembled nanogaps for molecular electronics

    DEFF Research Database (Denmark)

    Tang, Qingxin; Tong, Yanhong; Jain, Titoo;

    2009-01-01

    A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during se...

  7. Nanowire Solar Cells

    Science.gov (United States)

    Garnett, Erik C.; Brongersma, Mark L.; Cui, Yi; McGehee, Michael D.

    2011-08-01

    The nanowire geometry provides potential advantages over planar wafer-based or thin-film solar cells in every step of the photoconversion process. These advantages include reduced reflection, extreme light trapping, improved band gap tuning, facile strain relaxation, and increased defect tolerance. These benefits are not expected to increase the maximum efficiency above standard limits; instead, they reduce the quantity and quality of material necessary to approach those limits, allowing for substantial cost reductions. Additionally, nanowires provide opportunities to fabricate complex single-crystalline semiconductor devices directly on low-cost substrates and electrodes such as aluminum foil, stainless steel, and conductive glass, addressing another major cost in current photovoltaic technology. This review describes nanowire solar cell synthesis and fabrication, important characterization techniques unique to nanowire systems, and advantages of the nanowire geometry.

  8. Semiconductor nanowire lasers

    Science.gov (United States)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  9. Nanowire Growth for Photovoltaics

    DEFF Research Database (Denmark)

    Holm, Jeppe Vilstrup

    the light. The concentration and light trapping means that single junction nanowire solar cells have a higher theoretical maximum efficiency than equivalent planar solar cells. We have demonstrated the built-in light concentration of nanowires, by growing, contacting and characterizing a solar cell...... consisting of a single, vertical, gallium arsenide(GaAs) nanowire grown on silicon with a radial p-i-n-junction. The average concentration was ~8, and the peak concentration was ~12. By increasing the number of junctions in solar cells, they can extract more energy per absorbed photon. In ideal multi......Solar cells commercial success is based on an efficiency/cost calculation. Nanowire solar cells is one of the foremost candidates to implement third generation photo voltaics, which are both very efficient and cheap to produce. This thesis is about our progress towards commercial nanowire solar...

  10. Light-controlled drug releasing polymer films combining LbL self-assembly and host-guest interactions

    Directory of Open Access Journals (Sweden)

    J. Li

    2014-03-01

    Full Text Available By combining LbL (layer-by-layer self-assembly approach and host-guest interactions, a unique multilayer film was constructed and employed for a light-controlled drug release system. The drug molecules can be loaded and released into the resulting polyelectrolyte multilayers containing azobenzene (Azo function groups by using the irradiation of visible light and UV light alternately. The photo-sensitivity of the multilayer films was studied through UV-vis spectrum, fluorescence spectrum and confocal microscopy. The target molecules could be rapidly released from the multilayers after 300 W UV light irradiation for 20 minutes. Moreover, they could be readsorbed into the multilayers uniformly when illuminated under the 300 W visible light for 10 minutes confirmed by the observation of confocal microscopy, and the readsorption ratio exceeds 100% evidenced from UV–vis spectroscopy. After several cycles of the above-mentioned process, the multilayer films show good fatigue resistance. All these results indicate the photo-sensitivity and high-efficiency of the multilayer films, which have great potential in controlled drug delivery platform and biomedical applications.

  11. Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings

    Science.gov (United States)

    Gifford, Erika; Wang, Z.; Ramachandran, S.; Heflin, J. R.

    2007-09-01

    Ionic self-assembled multilayers (ISAMs) adsorbed on long period fiber gratings (LPGs) can serve as an inexpensive, robust, portable, biosensor platform. The ISAM technique is a layer-by-layer deposition technique that creates thin films on the nanoscale level. The combination of ISAMs with LPGs yields exceptional sensitivity of the optical fiber transmission spectrum. We have shown theoretically that the resonant wavelength shift for a thin-film coated LPG can be caused by the variation of the film's refractive index and/or the variation of the thickness of the film. We have experimentally demonstrated that the deposition of nm-thick ISAM films on LPGs induces shifts in the resonant wavelength of > 1.6 nm per nm of thin film. It has also been shown that the sensitivity of the LPG to the thickness of the ISAM film increases with increased film thickness. We have further demonstrated that ISAM-coated LPGs can function effectively as biosensors by using the biotin-streptavidin system and by using the Bacillus anthracis (Anthrax) antibody- PA (Protective Antigen) system. Experiments have been successfully performed in both air and solution, which illustrates the versatility of the biosensor. The results confirm that ISAM-LPGs yield a reusable, thermally-stable, and robust platform for designing and building efficient optical biosensors.

  12. Preparation and Preliminary Dielectric Characterization of Structured C60-Thiol-Ene Polymer Nanocomposites Assembled Using the Thiol-Ene Click Reaction

    Directory of Open Access Journals (Sweden)

    Hanaa M. Ahmed

    2015-11-01

    Full Text Available Fullerene-containing materials have the ability to store and release electrical energy. Therefore, fullerenes may ultimately find use in high-voltage equipment devices or as super capacitors for high electric energy storage due to this ease of manipulating their excellent dielectric properties and their high volume resistivity. A series of structured fullerene (C60 polymer nanocomposites were assembled using the thiol-ene click reaction, between alkyl thiols and allyl functionalized C60 derivatives. The resulting high-density C60-urethane-thiol-ene (C60-Thiol-Ene networks possessed excellent mechanical properties. These novel networks were characterized using standard techniques, including infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, and thermal gravimetric analysis (TGA. The dielectric spectra for the prepared samples were determined over a broad frequency range at room temperature using a broadband dielectric spectrometer and a semiconductor characterization system. The changes in thermo-mechanical and electrical properties of these novel fullerene-thiol-ene composite films were measured as a function of the C60 content, and samples characterized by high dielectric permittivity and low dielectric loss were produced. In this process, variations in chemical composition of the networks were correlated to performance characteristics.

  13. Self-assembled structures of 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol in hydrophobic polymer matrices prepared using different heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Wei-Chi, E-mail: wclai@mail.tku.edu.tw; Tseng, Shen-Jhen; Huang, Po-Hsun [Tamkang University, Department of Chemical and Materials Engineering (China)

    2015-11-15

    We report a method for tuning the nanoarchitectures of 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS) with poly(vinylidene fluoride) (PVDF) polymer matrices. Hydrophobic PVDF facilitated the formation of nanofibrils during heating. The self-assembly behaviors of DMDBS were further tuned by altering the different heat treatments. When the samples were prepared with a rapid heating rate (shorter annealing time), smaller amounts of melted PVDF were excluded due to the shorter time for aggregation of DMDBS, leading to larger complex structures of DMDBS and PVDF. Therefore, longer and thicker nanofibrils (around 100 nm) were observed using scanning electron microscopy. As the samples were prepared with a slow heating rate (longer annealing time), DMDBS had more time to aggregate, and therefore, larger amounts of melted PVDF were excluded. Smaller complex structures of DMDBS and PVDF caused the formation of shorter and thinner nanofibrils (around 40 nm). In addition, small-angle X-ray scattering results indicated that the longer and thicker nanofibrils were mostly excluded outside the PVDF crystalline bundles after cooling because they were too large to be easily incorporated between the PVDF crystalline lamellae. However, a large portion of the smaller and thinner nanofibrils was trapped between the crystalline lamellae after cooling due to their smaller sizes. As expected, the PVDF spherulitic morphologies were affected, but the PVDF crystalline microstructures were not significantly altered by the addition of DMDBS, as shown by the results from polarized optical microscopy and Fourier transform infrared spectroscopy.

  14. Self-assembled structures of 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol in hydrophobic polymer matrices prepared using different heat treatments

    International Nuclear Information System (INIS)

    We report a method for tuning the nanoarchitectures of 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS) with poly(vinylidene fluoride) (PVDF) polymer matrices. Hydrophobic PVDF facilitated the formation of nanofibrils during heating. The self-assembly behaviors of DMDBS were further tuned by altering the different heat treatments. When the samples were prepared with a rapid heating rate (shorter annealing time), smaller amounts of melted PVDF were excluded due to the shorter time for aggregation of DMDBS, leading to larger complex structures of DMDBS and PVDF. Therefore, longer and thicker nanofibrils (around 100 nm) were observed using scanning electron microscopy. As the samples were prepared with a slow heating rate (longer annealing time), DMDBS had more time to aggregate, and therefore, larger amounts of melted PVDF were excluded. Smaller complex structures of DMDBS and PVDF caused the formation of shorter and thinner nanofibrils (around 40 nm). In addition, small-angle X-ray scattering results indicated that the longer and thicker nanofibrils were mostly excluded outside the PVDF crystalline bundles after cooling because they were too large to be easily incorporated between the PVDF crystalline lamellae. However, a large portion of the smaller and thinner nanofibrils was trapped between the crystalline lamellae after cooling due to their smaller sizes. As expected, the PVDF spherulitic morphologies were affected, but the PVDF crystalline microstructures were not significantly altered by the addition of DMDBS, as shown by the results from polarized optical microscopy and Fourier transform infrared spectroscopy

  15. Three luminescent d10 metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu2+ ion and nitrobenzene

    Science.gov (United States)

    Wu, Wei-Ping; Liu, Ping; Liang, Yu-Tong; Cui, Lin; Xi, Zheng-Ping; Wang, Yao-Yu

    2015-08-01

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL2]n (1) and {[ML2]·(H2O)}n (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu2+ ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed.

  16. Nanoparticle self-assembly assisted by polymers: the role of shear stress in the nanoparticle arrangement of Langmuir and Langmuir-Blodgett films.

    Science.gov (United States)

    Martín-García, Beatriz; Velázquez, M Mercedes

    2014-01-21

    We propose to use the self-assembly ability of a block copolymer combined with compression-expansion cycles to obtain CdSe quantum dots (QDs) structures of different morphology. The methodology proposed consists in transferring onto mica mixed Langmuir monolayers of QDs and the polymer poly(styrene-co-maleic anhydride) partial 2-butoxyethyl ester cumene terminated, PS-MA-BEE, previously sheared by 50 compression-expansion cycles. Results indicate that the shear stress takes out nanoparticles at the air-water interface from metastable states and promotes a new equilibrium state of the Langmuir monolayer. This new state was transferred onto mica by the Langmuir-Blodgett (LB) methodology, and the morphology of the LB films was analyzed by atomic force microscopy and transmission electron microscopy measurements. Our results show that when the amplitude strain increases, the QDs domain size decreases and the QDs LB film arrangement becomes more ordered. The dynamics of the monolayer relaxation after cycling involves at least three time scales which are related to the damping of surface fluctuation, raft rearrangement, and component movements inside each raft. Brewster angle microscopy allowed visualizing in situ the raft rearrangement at the air-water interface.

  17. Self-assembly of silver(I) coordination polymers from aminopyrimidyl derivatives and malonate acid: From 1D chain to 2D layer

    Science.gov (United States)

    Sun, Di; Zhang, Na; Xu, Qin-Juan; Luo, Geng-Geng; Huang, Rong-Bin; Zheng, Lan-Sun

    2010-04-01

    Two new silver(I) coordination polymers (CPs) of the formula [Ag 2(dmapym) 4(mal)·H 2O] n ( 1) and [Ag 3(apym) 3(mal)NO 3] n ( 2) (dmapym = 2-amino-4,6-dimethylprimidine, apym = 2-aminopyrimidine, H 2mal = malonate) have been synthesized by reactions of AgNO 3 and 2-aminopyrimidyl ligands with malonate under the ammoniacal condition. Both complexes have been characterized by element analysis, IR and single-crystal X-ray diffraction. The monodentate dmapym and tridentate mal ligands link Ag(I) ions to give complex 1 a one-dimensional (1D) H-shaped chain structure. The complex 2 is a two-dimensional (2D) double sheet structure constructed by (4, 4) single sheet. Additionally, the hydrogen-bonding and C-H⋯π interactions also direct the self-assembly of supramolecular architectures. The photoluminescence properties of the 1 and 2 were investigated in the solid state at room temperature.

  18. Method of making hermetic seals for hermetic terminal assemblies

    Science.gov (United States)

    Hsu, John S.; Marlino, Laura D.; Ayers, Curtis W.

    2010-04-13

    This invention teaches methods of making a hermetic terminal assembly comprising the steps of: inserting temporary stops, shims and jigs on the bottom face of a terminal assembly thereby blocking assembly core open passageways; mounting the terminal assembly inside a vacuum chamber using a temporary assembly perimeter seal and flange or threaded assembly interfaces; mixing a seal admixture and hardener in a mixer conveyor to form a polymer seal material; conveying the polymer seal material into a polymer reservoir; feeding the polymer seal material from the reservoir through a polymer outlet valve and at least one polymer outlet tube into the terminal assembly core thereby filling interstitial spaces in the core adjacent to service conduits, temporary stop, and the terminal assembly casing; drying the polymer seal material at room temperature thereby hermetically sealing the core of the terminal assembly; removing the terminal assembly from the vacuum chamber, and; removing the temporary stops, shims.

  19. Modifications in optical and electrical properties of selenium nanowire arrays using ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Narinder [Chaudhary Devi Lal University, Department of Physics, Sirsa (India); Haryana College of Technology and Management, Department of Physics, Kaithal (India); Kumar, Rajesh [RN College of Engineering and Technology, Department of Physics, Madlauda (India); Kumar, Sushil [Chaudhary Devi Lal University, Department of Physics, Sirsa (India); Chakarvarti, S.K. [Manav Rachana International University, Research and Development, Faridabad (India)

    2015-11-15

    In the present paper, 80 MeV Si{sup 7+} ion beam-induced changes in selenium nanowire arrays, fabricated on copper substrates, have been examined. The nanowire arrays were electrodeposited into polymer membranes using template method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy have been used to study the ion-induced effects in fabricated nanowire arrays. The XRD and FESEM results confirmed the formation of selenium nanowire arrays with trigonal structures. An intensity variation in the XRD peaks is observed for irradiated nanowires at different ion fluences. The band gap energy of the irradiated nanowire arrays was found to reduce compared with the pristine case. The irradiation of semiconducting selenium nanowires enhances the electrical conductivity. The current-voltage characterizations also confirm an enhancement in electrical conductivity of selenium nanowire arrays with an increase in ion fluence. This study is anticipated to greatly facilitate the design and development of nanodevices-based semiconductor nanowires which can be utilized even in the harsh environment. (orig.)

  20. Modifications in optical and electrical properties of selenium nanowire arrays using ion beam irradiation

    International Nuclear Information System (INIS)

    In the present paper, 80 MeV Si7+ ion beam-induced changes in selenium nanowire arrays, fabricated on copper substrates, have been examined. The nanowire arrays were electrodeposited into polymer membranes using template method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy have been used to study the ion-induced effects in fabricated nanowire arrays. The XRD and FESEM results confirmed the formation of selenium nanowire arrays with trigonal structures. An intensity variation in the XRD peaks is observed for irradiated nanowires at different ion fluences. The band gap energy of the irradiated nanowire arrays was found to reduce compared with the pristine case. The irradiation of semiconducting selenium nanowires enhances the electrical conductivity. The current-voltage characterizations also confirm an enhancement in electrical conductivity of selenium nanowire arrays with an increase in ion fluence. This study is anticipated to greatly facilitate the design and development of nanodevices-based semiconductor nanowires which can be utilized even in the harsh environment. (orig.)

  1. Noble metal nanowires: from plasmon waveguides to passive and active devices.

    Science.gov (United States)

    Lal, Surbhi; Hafner, Jason H; Halas, Naomi J; Link, Stephan; Nordlander, Peter

    2012-11-20

    converters, an optical function not yet achievable with conventional diffraction-limited optical components. Nanowires can also serve as highly directional broadband optical antennas. When assembled into networks, plasmonic nanowires can be used to create optical devices, such as interferometric logic gates. Individual nanowires function as multiple input and output terminals in branched network geometries, where light incident on one wire can turn the emission from one or more output wires on or off. Nanowire-based devices that could exploit this effect include nanoscale routers and multiplexers, light modulators, and a complete set of Boolean logic functions.

  2. Sputter deposition of aluminium on colloidal polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Rainer; Buffet, Adeline; Couet, Sebastien; Schlage, Kai; Roth, Stephan V.; Roehlsberger, Ralf [HASYLAB, DESY, Hamburg (Germany); Herzog, Gerd [HASYLAB, DESY, Hamburg (Germany); Inst. f. Exp. Phys., Univ. Hamburg (Germany); Kaune, Gunar; Koerstgens, Volker; Meier, Robert; Metwalli, Ezzeldin; Mueller-Buschbaum, Peter [TU Muenchen, Physik-Department, Garching (Germany); Wurth, Wilfried [Inst. f. Exp. Phys., Univ. Hamburg (Germany)

    2009-07-01

    This work addresses an approach to the formation of metal nanowire meshes on surfaces. Colloidal dispersions of 100 nm polystyrene spheres were spincoated on silicon. Islands of packed layers of spheres were formed which served as template for sputter deposition of aluminium. Structure formation was investigated with grazing incidence small angle X-ray scattering at beamline BW4 at HASYLAB/DESY using an in-situ sputtering chamber, thus scattering could be observed during metal deposition. The measurements indicate, that at the beginning of the deposition the metal atoms assemble in the indentations between the spheres, only after longer sputtering times the surface becomes completely covered with aluminium. If an unsputtered sample was heated beyond the glass transition temperature the lateral ordering vanished, if sputtering was stopped before complete metal coverage ordering remained upon heating. This indicates that the metal forms a stable structure separating the polymer spheres from each other.

  3. From 1D to 3D - macroscopic nanowire aerogel monoliths.

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-08-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.

  4. From 1D to 3D - macroscopic nanowire aerogel monoliths.

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-08-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. PMID:27389477

  5. Data Mining as a Guide for the Construction of Crosslinked Nanoparticles with Low Immunotoxicity via Controlling Polymer Chemistry and Supramolecular Assembly

    Science.gov (United States)

    Elsabahy, Mahmoud; Wooley, Karen L.

    2015-01-01

    CONSPECTUS The potential immunotoxicity of nanoparticles that are currently being approved or in different phases of clinical trials or under rigorous in vitro and in vivo characterizations in several laboratories has recently raised special attention. Products with no apparent in vitro or in vivo toxicity may still trigger the various components of the immune system, unintentionally, and lead to serious adverse reactions. Cytokines are one of the useful biomarkers to predict the effect of biotherapeutics on modulating the immune system and for screening the immunotoxicity of nanoparticles, both in vitro and in vivo, and were found recently to partially predict the in vivo pharmacokinetics and biodistribution of nanomaterials. Control of polymer chemistry and supramolecular assembly provides a great opportunity for construction of biocompatible nanoparticles for biomedical clinical applications. However, the sources of data collected regarding immunotoxicities of nanomaterials are diverse and experiments are usually conducted using different assays and under specific conditions, making direct comparisons nearly impossible and, thus, tailoring properties of nanomaterials based on the available data is challenging. In this account, the effects of chemical structure, crosslinking, degradability, morphology, concentration and surface chemistry on the immunotoxicity of an expansive array of polymeric nanomaterials will be highlighted, with focus being given on assays conducted using the same in vitro and in vivo models and experimental conditions. Furthermore, numerical descriptive values have been utilized, uniquely, to stand for induction of cytokines by nanoparticles. This treatment of available data provides a simple and easy way to compare the immunotoxicity of various nanomaterials, and the values were found to correlate-well with published data. Based on the investigated polymeric systems in this study, valuable information has been collected that aids in the

  6. Three-dimensional GaN/AlN nanowire heterostructures by separating nucleation and growth processes.

    Science.gov (United States)

    Carnevale, Santino D; Yang, Jing; Phillips, Patrick J; Mills, Michael J; Myers, Roberto C

    2011-02-01

    Bottom-up nanostructure assembly has been a central theme of materials synthesis over the past few decades. Semiconductor quantum dots and nanowires provide additional degrees of freedom for charge confinement, strain engineering, and surface sensitivity-properties that are useful to a wide range of solid state optical and electronic technologies. A central challenge is to understand and manipulate nanostructure assembly to reproducibly generate emergent structures with the desired properties. However, progress is hampered due to the interdependence of nucleation and growth phenomena. Here we show that by dynamically adjusting the growth kinetics, it is possible to separate the nucleation and growth processes in spontaneously formed GaN nanowires using a two-step molecular beam epitaxy technique. First, a growth phase diagram for these nanowires is systematically developed, which allows for control of nanowire density over three orders of magnitude. Next, we show that by first nucleating nanowires at a low temperature and then growing them at a higher temperature, height and density can be independently selected while maintaining the target density over long growth times. GaN nanowires prepared using this two-step procedure are overgrown with three-dimensionally layered and topologically complex heterostructures of (GaN/AlN). By adjusting the growth temperature in the second growth step either vertical or coaxial nanowire superlattices can be formed. These results indicate that a two-step method allows access to a variety of kinetics at which nanowire nucleation and adatom mobility are adjustable. PMID:21265558

  7. Self-assembled functional molecular materials for optoelectronic applications

    OpenAIRE

    Kwok, CC; W. Lu; Che, CM

    2008-01-01

    There has been a growing interest to develop functional organic and organometallic materials in nano-scale by self assembly reactions as these materials could have unique electronic properties and applications. We have found that functionalized organometallic nano-wires which the formations are directed by weak Pt⋯Pt interactions along the dimension of the aggregates can be readily obtained by self-assembly reactions. These platinum(II) nano-wires exhibit interesting photophysical properties,...

  8. Application of nano-structured conducting polymers to humidity sensing

    Science.gov (United States)

    Park, Pilyeon

    Nanostructures, such as nanowires, nanocolumns, and nanotubes, have attracted a lot of attention because of their huge potential impact on a variety of applications. For sensor applications, nanostructures provide high surface area to volume ratios. The high surface area to volume ratio allows more reaction areas between target species and detection materials and also improves the detection sensitivity and response time. The main goal of this research was to exploit the advantages and develop innovative methods to accomplish the synthesis of nanowires and nano-coulmn conducting polymers used in humidity detection. To accomplish this, two fabrication methods are used. The first one utilizes the geometric confinement effect of a temporary nanochannel template to orient, precisely position, and assemble Polyaniline (PANI) nanowires as they are synthesized. The other approach is to simply spin-coat a polymer onto a substrate, and then oxygen plasma etch to generate a nano-columned Polyethylenedioxythiophene (PEDOT) thin film. 200 nm silicon oxide coated wafers with embedded platinum electrodes are used as a substrate for both fabrication methods. The biggest advantage of this first method is that it is simple, requires a single-step, i.e., synthesizing and positioning procedures are carried out simultaneously. The second method is potentially manufacturable and economic yet environmentally safe. These two methods do not produce extra nano-building materials to discard or create a health hazard. Both PANI nanowires and nano-columned PEDOT films have been tested for humidity detection using a system designed and built for this research to monitor response (current changes) to moisture, To explain the surface to volume ratio effect, 200 nm PANI nanowires and 10 microm PANI wires were directly compared for detecting moisture, and it was shown that the PANI nanowire had a better sensitivity. It was found difficult to monitor the behaviors of the PEDOT reaction to varying

  9. Facile and controllable one-step fabrication of molecularly imprinted polymer membrane by magnetic field directed self-assembly for electrochemical sensing of glutathione

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wanying; Jiang, Guoyi; Xu, Lei; Li, Bingzhi; Cai, Qizhi; Jiang, Huijun; Zhou, Xuemin, E-mail: xueminzhou001_001@hotmail.com

    2015-07-30

    Based on magnetic field directed self-assembly (MDSA) of the ternary Fe{sub 3}O{sub 4}@PANI/rGO nanocomposites, a facile and controllable molecularly imprinted electrochemical sensor (MIES) was fabricated through a one-step approach for detection of glutathione (GSH). The ternary Fe{sub 3}O{sub 4}@PANI/rGO nanocomposites were obtained by chemical oxidative polymerization and intercalation of Fe{sub 3}O{sub 4}@PANI into the graphene oxide layers via π–π stacking interaction, followed by reduction of graphene oxide in the presence of hydrazine hydrate. In molecular imprinting process, the pre-polymers, including GSH as template molecule, Fe{sub 3}O{sub 4}@PANI/rGO nanocomposites as functional monomers and pyrrole as both cross-linker and co-monomer, was assembled through N–H hydrogen bonds and the electrostatic interaction, and then was rapidly oriented onto the surface of MGCE under the magnetic field induction. Subsequently, the electrochemical GSH sensor was formed by electropolymerization. In this work, the ternary Fe{sub 3}O{sub 4}@PANI/rGO nanocomposites could not only provide available functionalized sites in the matrix to form hydrogen bond and electrostatic interaction with GSH, but also afford a promoting network for electron transfer. Moreover, the biomimetic sensing membrane could be controlled more conveniently and effectively by adjusting the magnetic field strength. The as-prepared controllable sensor showed good stability and reproducibility for the determination of GSH with the detection limit reaching 3 nmol L{sup −1} (S/N = 3). In addition, the highly sensitive and selective biomimetic sensor has been successfully used for the clinical determination of GSH in biological samples. - Highlights: • The ternary composites exhibited great conductivity and electrocatalytical activity. • By magnetic field induction, the orderly film was fabricated on the surface of MGCE. • The microstructure of the sensing membrane could be controlled

  10. Supramolecular polymers in inhomogeneous systems

    OpenAIRE

    Zweistra, H.J.A.

    2007-01-01

    This thesis describes theoretical results of supramolecular polymers in inhomogeneous systems. Supramolecular polymers are linear assemblies of which the monomers are joined by reversible bonds. Many types of supramolecular polymers have been synthesized in recent years. Moreover, there are numerous compounds in nature which exhibit similar behavior. Simulations of coarse-grained models of supramolecular polymers yielded new insights into the properties of supramolecular polymers in inhomogen...

  11. Synthesis and properties of Si and SiGe/Si nanowires

    Science.gov (United States)

    Redwing, Joan M.; Lew, Kok-Keong; Bogart, Timothy E.; Pan, Ling; Dickey, Elizabeth C.; Carim, A. H.; Wang, Yanfeng; Cabassi, Marco A.; Mayer, Theresa S.

    2004-06-01

    The fabrication of semiconductor nanowires, in which composition, size and conductivity can be controlled in both the radial and axial direction of the wire is of interest for fundamental studies of carrier confinement as well as nanoscale device development. In this study, group IV semiconductor nanowires, including Si, Ge and SixGe1-x alloy nanowires were fabricated by vapor-liquid-solid (VLS) growth using gaseous precursors. In the VLS process, gold is used to form a liquid alloy with Si and Ge which, upon supersaturation, precipitates a semiconductor nanowire. Nanoporous alumina membranes were used as templates for the VLS growth process, in order to control the diameter of the nanowires over the range from 45 nm to 200 nm. Intentional p-type and n-type doping was achieved through the addition of either trimethylboron, diborane or phosphine gas during nanowire growth. The electrical properties of undoped and intentionally doped silicon nanowires were characterized using field-assisted assembly to align and position the wires onto pre-patterned test bed structures. The depletion characteristics of back-gated nanowire structures were used to determine conductivity type and qualitatively compare dopant concentration. SiGe and SiGe/Si axial heterostructure nanowires were also prepared through the addition of germane gas during VLS growth. The Ge concentration in the wires was controllable over the range from 12 % to 25% by varying the inlet GeH4/SiH4 ratio.

  12. Guided growth of horizontal nanowires: A new path to self-integrated nanosystems

    Science.gov (United States)

    Joselevich, Ernesto

    2014-03-01

    The large-scale assembly of nanowires with controlled orientation on surfaces remains one of the most critical challenges toward their integration into practical devices. We report the vapor-liquid-solid growth of perfectly aligned, millimeter-long, horizontal GaN and ZnO nanowires with controlled crystallographic orientations on different planes of sapphire and other substrates. The growth directions, crystallographic orientation and faceting of the nanowires vary with each surface orientation, as determined by their epitaxial relationship with the substrate, as well as by a graphoepitaxial effect that guides their growth along surface steps and grooves. Despite their interaction with the surface, these horizontally grown nanowires display few structural defects, exhibiting optical and electronic properties comparable to those of vertically grown nanowires. Guided GaN nanowires and ZnO nanowires present general similarities and a few interesting differences, which shed light into the guided growth mechanism. The controlled horizontal growth of nanowires of different materials on different substrates proves the generality of the guided growth approach. Recently, we demonstrated the feasibility of massively parallel ``self-integration'' of NWs into functional systems based on guided growth, including hundreds of sing-NW based field-effect transistors made all at once, and complex logic circuits, such as a 3-bit address decoder. These examples highlight the potential of guided growth for the large-scale integration of nanowires into practical devices.

  13. Polymersomes via Self-Assembly of Amphiphilic β-Cyclodextrin-Centered Triarm Star Polymers for Enhanced Oral Bioavailability of Water-Soluble Chemotherapeutics.

    Science.gov (United States)

    Hu, Mengying; Shen, Yurun; Zhang, Lu; Qiu, Liyan

    2016-03-14

    To date, improving oral bioavailability of water-soluble drugs with poor membrane permeability is still challenging. An example of this includes doxorubicin hydrochloride (DOX·HCl), a widely used chemotherapeutic. We therefore developed a novel DOX·HCl-loaded polymersome (Ps-DOX·HCl) self-assembled by amphiphilic β-cyclodextrin-centered triarm star polymer (mPEG(2k)-PLA(3k))3-CD with the considerable drug loading capability. Using Madin-Darby canine kidney (MDCK) cells trans-well models, it was found that the cellular uptake and absorptive transport of DOX·HCl was significantly increased and the efflux was attenuated when delivered through polymersomes than free drugs. This phenomenon was further verified in mechanistic studies, which was attributed to the change in membrane transport pathway from paracellular route (free DOX·HCl) to active transcellular transport (drug-loaded polymersomes). Moreover, in vivo pharmacokinetic studies in mice demonstrated a significant increase in the oral bioavailability of Ps-DOX·HCl compared with free DOX·HCl (7.32-fold), as well as extended half-life (8.22-fold). This resulted in a substantial anticancer efficacy against mouse sarcoma 180 (S180) tumor in vivo. The cardiotoxicity, which is intrinsically induced by DOX·HCl, and toxicity toward gastrointestinal tissues were avoided according to histological studies. These findings indicate that (mPEG(2k)-PLA(3k))3-CD copolymer displays great potential as a vehicle for the effective oral delivery of water-soluble drugs with low permeability. PMID:26840277

  14. Molecular modeling in design of polyaniline for polymer-based carbon dioxide sensor

    OpenAIRE

    X. P. Chen

    2013-01-01

    Conducting polymers are attractive chemical sensing materials due to their outstanding characteristics including low cost, room-temperature operations, easy device fabrication, high sensitivity and short response time. The new nanowires architecture, with high surface-to-volume ratio, makes possible the conducting polymers an ultra fast detection of chemical at low concentrations. Polymer-coated nanowires are thus the potential cost effective solution for the new generation gas sensors. As a ...

  15. Magnetoelectric polymer nanocomposite for flexible electronics

    KAUST Repository

    Alnassar, M.

    2015-03-06

    This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites.

  16. Biofunctionalized Magnetic Nanowires

    KAUST Repository

    Kosel, Jurgen

    2013-12-19

    Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

  17. Multishelled Gold Nanowires

    OpenAIRE

    Bilalbegovic, G.

    1999-01-01

    The current miniaturization of electronic devices raises many questions about the properties of various materials at nanometre-scales. Recent molecular dynamics computer simulations have shown that small finite nanowires of gold exist as multishelled structures of lasting stability. These classical simulations are based on a well-tested embedded atom potential. Molecular dynamics simulation studies of metallic nanowires should help in developing methods for their fabrication, such as electron...

  18. PREFACE: IUMRS-ICA 2008 Symposium, Sessions 'X. Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science' and 'Y. Frontier of Polymeric Nano-Soft-Materials - Precision Polymer Synthesis, Self-assembling and Their Functionalization'

    Science.gov (United States)

    Takahara, Atsushi; Kawahara, Seiichi

    2009-09-01

    Tashiro (Toyota Technological Institute) Professor Kazuo Sakurai(Kitakyushu University) Professor Keiji Tanaka (Kyushu University) Dr Sono Sasaki (JASRI/Spring-8) Professor Naoya Torikai (KENS) Professor Moonhor Ree (POSTECH) Professor Kookheon Char (Seoul National University) Professor Charles C Han (CAS) Professor Atsushi Takahara(Kyushu University) Frontier of Polymeric Nano-Soft-Materials, Precision Polymer Synthesis, Self-assembling and Their Functionalization (Symposium Y of IUMRS-ICA2008) Seiichi Kawahara, Rong-Ming Ho, Hiroshi Jinnai, Masami Kamigaito, Takashi Miyata, Hiroshi Morita, Hideyuki Otsuka, Daewon Sohn, Keiji Tanaka It is our great pleasure and honor to publish peer-reviewed papers, presented in Symposium Y 'Frontier of Polymeric Nano-Soft-Materials Precision Polymer Synthesis, Self-assembling and Their Functionalization' at the International Union of Materials Research Societies International Conference in Asia 2008 (IUMRS-ICA2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. 'Polymeric nano-soft-materials' are novel outcomes based on a recent innovative evolution in polymer science, i.e. precision polymer synthesis, self-assembling and functionalization of multi-component systems. The materials are expected to exhibit specific functions and unique properties due to their hierarchic morphologies brought either by naturally-generated ordering or by artificial manipulation of the systems, e.g., crystallization and phase-separation. The emerging precision synthesis has brought out new types of polymers with well-controlled primary structures. Furthermore, the surface and interface of the material are recognized to play an important role in the outstanding mechanical, electrical and optical properties, which are required for medical and engineering applications. In order to understand structure-property relationships in the nano-soft-materials, it is indispensable to develop novel characterization techniques. Symposium Y

  19. Functionalized nanowires from electrospun polymer nanofibers

    Science.gov (United States)

    Ruiz, A.; Vega, E.; Katiyar, R.; Valentin, R.

    2007-05-01

    The ability to pattern materials in three dimensions is critical for several emerging technologies, including photonics, μfluidics, MEMS, and biomaterials. Electrospinning allows one to functionalized and rapidly fabricate materials in complex three-dimensional shapes without the need for expensive tooling, dies, or lithographic masks. Here, recent advances in functionalization techniques are reviewed with an emphasis on the push toward patterning finer feature sizes. Effects of material and process parameters on the diameter of electrospun Poly Ethylene Oxide (PEO) fibers were experimentally investigated. Experiments were conducted at the settings of solution flow rate, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant fiber diameter. All the factors were found statistically significant in the production of nanoscale fibers. Opportunities and challenges associated with electrospinning of polyacrylonitrile fibers are also highlighted.

  20. Chemical Modification of Porous Alumina for Nanowire Templating and NEXAFS Spectroscopy of Aqueous ATP

    OpenAIRE

    Kelly, Daniel Nicholas

    2010-01-01

    Part One: Chemical Modification of Porous Alumina for Nanowire Templating: A modified sol-gel technique and subsequent polymer coating technique was used to modify the size of nanowires grown via electrodeposition in porous alumina templates. The porous alumina film is initially soaked in a water-containing solution prior to exposure to a different solution of 3-aminopropyltriethoxysilane in toluene. The amount of water in the aqueous solution correlates with the thickness of silane coating ...

  1. Nanowire structures and electrical devices

    Science.gov (United States)

    Bezryadin, Alexey; Remeika, Mikas

    2010-07-06

    The present invention provides structures and devices comprising conductive segments and conductance constricting segments of a nanowire, such as metallic, superconducting or semiconducting nanowire. The present invention provides structures and devices comprising conductive nanowire segments and conductance constricting nanowire segments having accurately selected phases including crystalline and amorphous states, compositions, morphologies and physical dimensions, including selected cross sectional dimensions, shapes and lengths along the length of a nanowire. Further, the present invention provides methods of processing nanowires capable of patterning a nanowire to form a plurality of conductance constricting segments having selected positions along the length of a nanowire, including conductance constricting segments having reduced cross sectional dimensions and conductance constricting segments comprising one or more insulating materials such as metal oxides.

  2. Flexible White Light Emitting Diodes Based on Nitride Nanowires and Nanophosphors

    OpenAIRE

    Guan, Nan; Dai, Xing; Messanvi, Agnes; Zhang, Hezhi; Yan, Jianchang; Gautier, E.; Bougerol, Catherine; Durand, Christophe; Eymery, Joël; Tchernycheva, Maria

    2016-01-01

    International audience We report the first demonstration of a flexible white phosphor-converted light emitting diodes (LEDs) based on p-n junction core/shell nitride nanowires. GaN nanowires containing 7 radial In 0.2 Ga 0.8 N/GaN quantum wells were grown by metal-organic chemical vapor deposition on a sapphire substrate by a catalyst-free approach. To fabricate the flexible LED, the nanowires are embedded into a phosphor-doped polymer matrix, peeled off from the growth substrate and conta...

  3. Control of photon transport properties in nanocomposite nanowires

    Science.gov (United States)

    Moffa, M.; Fasano, V.; Camposeo, A.; Persano, L.; Pisignano, D.

    2016-02-01

    Active nanowires and nanofibers can be realized by the electric-field induced stretching of polymer solutions with sufficient molecular entanglements. The resulting nanomaterials are attracting an increasing attention in view of their application in a wide variety of fields, including optoelectronics, photonics, energy harvesting, nanoelectronics, and microelectromechanical systems. Realizing nanocomposite nanofibers is especially interesting in this respect. In particular, methods suitable for embedding inorganic nanocrystals in electrified jets and then in active fiber systems allow for controlling light-scattering and refractive index properties in the realized fibrous materials. We here report on the design, realization, and morphological and spectroscopic characterization of new species of active, composite nanowires and nanofibers for nanophotonics. We focus on the properties of light-confinement and photon transport along the nanowire longitudinal axis, and on how these depend on nanoparticle incorporation. Optical losses mechanisms and their influence on device design and performances are also presented and discussed.

  4. Structural and electrical characterization of hybrid metal-polypyrrole nanowires

    Science.gov (United States)

    Gence, L.; Faniel, S.; Gustin, C.; Melinte, S.; Bayot, V.; Callegari, V.; Reynes, O.; Demoustier-Champagne, S.

    2007-09-01

    We present here the synthesis and structural characterization of hybrid Au-polypyrrole-Au and Pt-polypyrrole-Au nanowires together with a study of their electrical properties from room temperature down to very low temperature. A careful characterization of the metal-polymer interfaces by transmission electron microscopy revealed that the structure and mechanical strength of bottom and upper interfaces are very different. Variable temperature electrical transport measurements were performed on both multiple nanowires—contained within the polycarbonate template—and single nanowires. Our data show that the three-dimensional Mott variable-range-hopping model provides a complete framework for the understanding of transport in polypyrrole nanowires, including nonlinear current-voltage characteristics and magnetotransport at low temperatures.

  5. Investigation of superconducting properties of nanowires prepared by template synthesis

    Science.gov (United States)

    Michotte, S.; Mátéfi-Tempfli, S.; Piraux, L.

    2003-05-01

    We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have a uniform diameter of ~40 nm and a very large aspect ratio (~500). The diameter of the nanowires is small enough to ensure a one-dimensional superconducting regime in a wide temperature range below Tc. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied dc current (or voltage). The current-induced breakdowns in the voltage-current characteristics may be explained by the formation of phase slip centres. Moreover, dc voltage driven measurements reveal the existence of a new S-shape behaviour near the formation of these phase slip centres.

  6. Investigation of superconducting properties of nanowires prepared by template synthesis

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have a uniform diameter of ∼40 nm and a very large aspect ratio (∼500). The diameter of the...... nanowires is small enough to ensure a one-dimensional superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied...... dc current (or voltage). The current-induced breakdowns in the voltage-current characteristics may be explained by the formation of phase slip centres. Moreover, dc voltage driven measurements reveal the existence of a new S-shape behaviour near the formation of these phase slip centres....

  7. Nanostructured polymers for photonics

    OpenAIRE

    Chantal Paquet; Eugenia Kumacheva

    2008-01-01

    We review recent progress in the development of polymer nanostructured materials with periodic structures and compositions having applications in photonics and optical data storage. This review provides a brief description of the microfabrication and self-assembly methods used for the production of polymer materials with periodic structures, and highlights the properties and applications of photonic materials derived from block copolymers, colloid crystals, and microfabricated polymers. We co...

  8. Rapid Low-Temperature 3D Integration of Silicon Nanowires on Flexible Substrates.

    Science.gov (United States)

    Kim, Yoonkap; Kim, Han-Jung; Kim, Jae-Hyun; Choi, Dae-Geun; Choi, Jun-Hyuk; Jung, Joo-Yun; Jeon, Sohee; Lee, Eung-Sug; Jeong, Jun-Ho; Lee, Jihye

    2015-08-26

    The vertical integration of 1D nanostructures onto the 2D substrates has the potential to offer significant performance gains to flexible electronic devices due to high integration density, large surface area, and improved light absorption and trapping. A simple, rapid, and low temperature transfer bonding method has been developed for this purpose. Ultrasonic vibration is used to achieve a low temperature bonding within a few seconds, resulting in a polymer-matrix-free, electrically conducting vertical assembly of silicon nanowires (SiNWs) with a graphene/PET substrate. The microscopic structure, and mechanical and electrical characteristics of the interface between the transferred SiNW array and graphene layer are subsequently investigated, revealing that this creates a mechanically robust and electrically Ohmic contact. This newly developed ultrasonic transfer bonding technique is also found to be readily adaptable for diverse substrates of both metal and polymer. It is therefore considered as a valuable technique for integrating 1D vertical nanostructures onto the 2D flexible substrates for flexible photovoltaics, energy storage, and water splitting systems.

  9. Encapsulation of Polythiophene by Glycopolymer for Water Soluble Nano-wire

    Energy Technology Data Exchange (ETDEWEB)

    T Fukuda; Y Inoue; T Koga; M Matsuoka; Y Miura

    2011-12-31

    A water-soluble polythiophene (PT) was prepared by the self-assembling complex with a glycopolymer. The glycopolymer of poly(N-p-vinylbenzyl-D-lactonamide) (PVLA) formed self-assembling cylindrical structure based on the amphiphilicity even after the complexation with PT. We confirmed the improved optical functionality of PT due to the longer conjugated {pi}-orbital. It suggested that PT behaved like molecular nanowire with the self-assembled structure in the hydrophobic core of PVLA. PVLA-PT also showed specific biorecognition against corresponding lectin. These results suggested that the bioactive nanowire formation of PT with the glycopolymer was developed.

  10. Nanoparticle-mediated nonclassical crystal growth of sodium fluorosilicate nanowires and nanoplates

    Directory of Open Access Journals (Sweden)

    Hongxia Li

    2011-12-01

    Full Text Available We observed nonclassical crystal growth of the sodium fluorosilicate nanowires, nanoplates, and hierarchical structures through self-assembly and aggregation of primary intermediate nanoparticles. Unlike traditional ion-by-ion crystallization, the primary nanoparticles formed first and their subsequent self-assembly, fusion, and crystallization generated various final crystals. These findings offer direct evidences for the aggregation-based crystallization mechanism.

  11. Fabrication of transition metal-containing nanostructures via polymer templates for a multitude of applications

    Science.gov (United States)

    Lu, Jennifer Qing

    Nanostructures such as carbon nanotubes and semiconducting nanowires offer great technological promise due to their remarkable properties. The lack of a rational synthesis method prevents fabricating these nanostructures with desirable and consistent properties at predefined locations for device applications. In this thesis, employing polymer templates, a variety of highly ordered catalytically active transition metal nanostructures, ranging from single metallic nanoparticles of Fe, Co, Ni, Au and bimetallic nanoparticles of Ni/Fe and Co/Mo to Fe-rich silicon oxide nanodomains with uniform and tunable size and spacing have been successfully synthesized. These nanostructures have been demonstrated to be excellent catalyst systems for the synthesis of carbon nanotube and silicon nanowire. High quality, small diameter carbon nanotubes and nanowires with narrow size distribution have been successfully attained. Because these catalytically active nanostructures are uniformly distributed and do not agglomerate at the growth temperatures, uniform, high density and high quality carbon nanotube mats have been obtained. Since this polymer template approach is fully compatible with conventional top-down photolithography, lithographically selective growth of carbon nanotubes on a surface or suspended carbon nanotubes across trenches have been produced by using existing semiconductor processing. We have also shown the feasibility of producing carbon nanotubes and silicon nanowires at predefined locations on a wafer format and established a wafer-level carbon nanotube based device fabrication process. The ability of the polymer template approach to control catalyst systems at the nano-, micro- and macro-scales paves a pathway for commercialization of these 1D nanostructure-enabled devices. Beside producing well-defined, highly ordered discrete catalytically active metal-containing nanostructures by the polymer template approach, Au and Ag nanotextured surfaces have also been

  12. Fullerene-based one-dimensional crystalline nanopolymer formed through topochemical transformation of the parent nanowire

    DEFF Research Database (Denmark)

    Geng, Junfeng; Solov'yov, Ilia; Reid, David G.;

    2010-01-01

    Large-scale practical applications of fullerene (C_60) in nanodevices could be significantly facilitated if the commercially available micrometer-scale raw C_60 powder were further processed into a one-dimensional nanowire-related polymer displaying covalent bonding as molecular interlinks...... and resembling traditional important conjugated polymers. However, there has been little study thus far in this area despite the abundant literature on fullerene. Here we report the preparation and characterization of such a C_60-based polymer nanowire, (-C_60.TMB-)_n, where TMB=1,2,4-trimethylbenzene, which...... displays a well-defined crystalline nanostructure, exceptionally large length-to-width ratio and excellent thermal stability. The material is prepared by first growing the corresponding nanowire through a solution phase of C_60 followed by a topochemical polymerization reaction in the solid state. Gas...

  13. The Novel Semiconductor Nanowire Heterostructures

    Institute of Scientific and Technical Information of China (English)

    J.Q.Hu; Y.Bando; J.H.Zhan; D.Golberg

    2007-01-01

    1 Results If one-dimensional heterostructures with a well-defined compositional profile along the wire radial or axial direction can be realized within semiconductor nanowires, new nano-electronic devices,such as nano-waveguide and nano-capcipator, might be obtained. Here,we report the novel semiconducting nanowire heterostructures:(1) Si/ZnS side-to-side biaxial nanowires and ZnS/Si/ZnS sandwich-like triaxial nanowires[1],(2) Ga-Mg3N2 and Ga-ZnS metal-semiconductor nanowire heterojunctions[2-3]and (3) ...

  14. Strain analysis of nanowire interfaces in multiscale composites

    Science.gov (United States)

    Malakooti, Mohammad H.; Zhou, Zhi; Spears, John H.; Shankwitz, Timothy J.; Sodano, Henry A.

    2016-04-01

    Recently, the reinforcement-matrix interface of fiber reinforced polymers has been modified through grafting nanostructures - particularly carbon nanotubes and ZnO nanowires - on to the fiber surface. This type of interface engineering has made a great impact on the development of multiscale composites that have high stiffness, interfacial strength, toughness, and vibrational damping - qualities that are mutually exclusive to a degree in most raw materials. Although the efficacy of such nanostructured interfaces has been established, the reinforcement mechanisms of these multiscale composites have not been explored. Here, strain transfer across a nanowire interphase is studied in order to gain a heightened understanding of the working principles of physical interface modification and the formation of a functional gradient. This problem is studied using a functionally graded piezoelectric interface composed of vertically aligned lead zirconate titanate nanowires, as their piezoelectric properties can be utilized to precisely control the strain on one side of the interface. The displacement and strain across the nanowire interface is captured using digital image correlation. It is demonstrated that the material gradient created through nanowires cause a smooth strain transfer from reinforcement phase into matrix phase that eliminates the stress concentration between these phases, which have highly mismatched elasticity.

  15. Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels%Hydrogen Bonded Supramolecular Polymers in Both Apolar and Aqueous Media: Self-Assembly and Reversible Conversion of Vesicles and Gels

    Institute of Scientific and Technical Information of China (English)

    杜平; 孔军; 王贵涛; 赵新; 李光玉; 蒋锡夔; 黎占亭

    2011-01-01

    In a preliminary letter (Tetrahedron Lett. 2010, 51, 188), we reported two new hydrazide-based quadruple hydrogen-bonding motifs, this is, two monopodal (la and lb) and five dipodal (2a, 2b and 3a--3c) aromatic hydrazide derivatives, and the formation of supramolecular polymers and vesicles from the dipodal motifs in hydrocarbons. In this paper, we present a full picture on the properties of these hydrogen-bonding motifs with an emphasis on their self-assembling behaviors in aqueous media. SEM, AFM, TEM and fluorescent micrographs indicate that all the dipodal compounds also form vesicles in polar methanol and water-methanol (up to 50% of water) mixtures. Control experiments show that lb does not form vesicles in same media. Addition of lb to the solution of the dipodal compounds inhibits the latter's capacity of forming vesicles. At high concentrations, 3b and 3c also gelate discrete solvents, including hydrocarbons, esters, methanol, and methanol-water mixture. Concentration-dependent SEM investigations reveal that the vesicles of 3b and 3c fuse to form gels and the gel of 3c can de-aggregate to form the vesicles reversibly.

  16. Measuring the specific contact resistance of contacts to semiconductor nanowires

    Science.gov (United States)

    Mohney, S. E.; Wang, Y.; Cabassi, M. A.; Lew, K. K.; Dey, S.; Redwing, J. M.; Mayer, T. S.

    2005-02-01

    Ohmic contacts to semiconductor nanowires are essential components of many new nanoscale electronic devices. Equations for extracting specific contact resistance (or contact resistivity) from several different test structures have been developed by modeling the metal/semiconductor contact as a transmission line, leading to the development of equations analogous to those used for planar contacts. The advantages and disadvantages of various test structures are discussed. To fabricate test structures using a convenient four-point approach, silicon nanowires have been aligned using field-assisted assembly and contacts fabricated. Finally, specific contact resistances near 5 × 10 -4 Ω cm 2 have been measured for Ti/Au contacts to p-type Si nanowires with diameters of 78 and 104 nm.

  17. Creating New VLS Silicon Nanowire Contact Geometries by Controlling Catalyst Migration

    DEFF Research Database (Denmark)

    Alam, Sardar Bilal; Panciera, Federico; Hansen, Ole;

    2015-01-01

    The formation of self-assembled contacts between vapor-liquid-solid grown silicon nanowires and flat silicon surfaces was imaged in situ using electron microscopy. By measuring the structural evolution of the contact formation process, we demonstrate how different contact geometries are created by...... adjusting the balance between silicon deposition and Au migration. We show that electromigration provides an efficient way of controlling the contact. The results point to novel device geometries achieved by direct nanowire growth on devices....

  18. Piezoresistive boron doped diamond nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Wang, Xinpeng

    2016-09-13

    A UNCD nanowire comprises a first end electrically coupled to a first contact pad which is disposed on a substrate. A second end is electrically coupled to a second contact pad also disposed on the substrate. The UNCD nanowire is doped with a dopant and disposed over the substrate. The UNCD nanowire is movable between a first configuration in which no force is exerted on the UNCD nanowire and a second configuration in which the UNCD nanowire bends about the first end and the second end in response to a force. The UNCD nanowire has a first resistance in the first configuration and a second resistance in the second configuration which is different from the first resistance. The UNCD nanowire is structured to have a gauge factor of at least about 70, for example, in the range of about 70 to about 1,800.

  19. Combined main-chain/side-chain ionic liquid crystalline polymer based on ‘jacketing’ effect: Design, synthesis, supra-molecular self-assembly and photophysical properties

    Directory of Open Access Journals (Sweden)

    L. Weng

    2015-06-01

    Full Text Available Reasonably fabricating ordered structures of ionic polymers is very important for the development of novel functional materials. By combining the ions and liquid cry stalline polymer, we successfully designed and synthesized a series of novel combined main-chain/side-chain ionic liquid crystalline polymer (MCSC-ILCPs containing imidazolium groups and different counter-anions, poly (2,5-bis{[6-(4-butoxy-4'-imidazolium biphenylhexyl]oxycarbonyl}styrene salts poly(BImBHCS-X with the following types of counter-anions (Br¯, BF4¯, PF6¯ and TFSI¯. Combined technologies confirmed the chemical structures of the monomers and polymers with imidazolium cation and different counter-anions. Differential scanning calorimetry (DSC, polarized light microscopy (PLM and one- and two-dimensional wide-angle X-ray diffraction (1D and 2D WAXD results illustrated that the LC structures and the transitions of ordered structures depended on the nature of the counter-anion employed. The polymers with Br¯ and BF4¯ counter-anions exhibited smectic A (SmA LC behavior below the isotropic temperature. The another one, poly(BImBHCS–TFSI with the large volume of the TFSI¯ anion destroyed the packing of the LC ordered structure resulting in an amorphous structure. The photophysical properties of the polymers prepared can be adjusted by tuning the ionic interaction of the polymers by switching the counter-anion.

  20. Single-nanowire photoelectrochemistry

    Science.gov (United States)

    Su, Yude; Liu, Chong; Brittman, Sarah; Tang, Jinyao; Fu, Anthony; Kornienko, Nikolay; Kong, Qiao; Yang, Peidong

    2016-07-01

    Photoelectrochemistry is one of several promising approaches for the realization of efficient solar-to-fuel conversion. Recent work has shown that photoelectrodes made of semiconductor nano-/microwire arrays can have better photoelectrochemical performance than their planar counterparts because of their unique properties, such as high surface area. Although considerable research effort has focused on studying wire arrays, the inhomogeneity in the geometry, doping, defects and catalyst loading present in such arrays can obscure the link between these properties and the photoelectrochemical performance of the wires, and correlating performance with the specific properties of individual wires is difficult because of ensemble averaging. Here, we show that a single-nanowire-based photoelectrode platform can be used to reliably probe the current–voltage (I–V) characteristics of individual nanowires. We find that the photovoltage output of ensemble array samples can be limited by poorly performing individual wires, which highlights the importance of improving nanowire homogeneity within an array. Furthermore, the platform allows the flux of photogenerated electrons to be quantified as a function of the lengths and diameters of individual nanowires, and we find that the flux over the entire nanowire surface (7–30 electrons nm–2 s–1) is significantly reduced as compared with that of a planar analogue (∼1,200 electrons nm–2 s–1). Such characterization of the photogenerated carrier flux at the semiconductor/electrolyte interface is essential for designing nanowire photoelectrodes that match the activity of their loaded electrocatalysts.

  1. Spatially controlled synthesis of silver nanoparticles and nanowires by photosensitized reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jradi, S; Zeng, X H; Plain, J; Royer, P; Bachelot, R; Akil, S [Laboratoire de Nanotechnologie et d' Instrumentation Optique, ICD CNRS FRE 2848, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France); Balan, L; Lougnot, D J; Soppera, O; Vidal, L, E-mail: lavinia.balan@uha.fr [Institut de Science des Materiaux de Mulhouse CNRS LRC 7228, 15 rue Jean Starcky, 68057 Mulhouse (France)

    2010-03-05

    The present paper reports on the spatially controlled synthesis of silver nanoparticles (NPs) and silver nanowires by photosensitized reduction. In a first approach, direct photogeneration of silver NPs at the end of an optical fiber was carried out. Control of both size and density of silver NPs was possible by changing the photonic conditions. In a further development, a photochemically assisted procedure allowing silver to be deposited at the surface of a polymer microtip was implemented. Finally, polymer tips terminated by silver nanowires were fabricated by simultaneous photopolymerization and silver photoreduction. The silver NPs were characterized by UV-visible spectroscopy and scanning electron microscopy.

  2. Electrodeposition of Cobalt Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sungbok; Hong, Kimin [Chungnam National Univ., Daejeon (Korea, Republic of)

    2013-03-15

    We developed an electroplating process of cobalt nanowires of which line-widths were between 70 and 200 nm. The plating electrolyte was made of CoSO{sub 4} and an organic additive, dimethyldithiocarbamic acid ester sodium salt (DAESA). DAESA in plating electrolytes had an accelerating effect and reduced the surface roughness of plated cobalt thin films. We obtained void-free cobalt nanowires when the plating current density was 6.25 mA/cm{sup 2} and DAESA concentration was 1 mL/L.

  3. EDITORIAL: Nanowires for energy Nanowires for energy

    Science.gov (United States)

    LaPierre, Ray; Sunkara, Mahendra

    2012-05-01

    This special issue of Nanotechnology focuses on studies illustrating the application of nanowires for energy including solar cells, efficient lighting and water splitting. Over the next three decades, nanotechnology will make significant contributions towards meeting the increased energy needs of the planet, now known as the TeraWatt challenge. Nanowires in particular are poised to contribute significantly in this development as presented in the review by Hiralal et al [1]. Nanowires exhibit light trapping properties that can act as a broadband anti-reflection coating to enhance the efficiency of solar cells. In this issue, Li et al [2] and Wang et al [3] present the optical properties of silicon nanowire and nanocone arrays. In addition to enhanced optical properties, core-shell nanowires also have the potential for efficient charge carrier collection across the nanowire diameter as presented in the contribution by Yu et al [4] for radial junction a-Si solar cells. Hybrid approaches that combine organic and inorganic materials also have potential for high efficiency photovoltaics. A Si-based hybrid solar cell is presented by Zhang et al [5] with a photoconversion efficiency of over 7%. The quintessential example of hybrid solar cells is the dye-sensitized solar cell (DSSC) where an organic absorber (dye) coats an inorganic material (typically a ZnO nanostructure). Herman et al [6] present a method of enhancing the efficiency of a DSSC by increasing the hetero-interfacial area with a unique hierarchical weeping willow ZnO structure. The increased surface area allows for higher dye loading, light harvesting, and reduced charge recombination through direct conduction along the ZnO branches. Another unique ZnO growth method is presented by Calestani et al [7] using a solution-free and catalyst-free approach by pulsed electron deposition (PED). Nanowires can also make more efficient use of electrical power. Light emitting diodes, for example, will eventually become the

  4. Nanostructured polymers for photonics

    Directory of Open Access Journals (Sweden)

    Chantal Paquet

    2008-04-01

    Full Text Available We review recent progress in the development of polymer nanostructured materials with periodic structures and compositions having applications in photonics and optical data storage. This review provides a brief description of the microfabrication and self-assembly methods used for the production of polymer materials with periodic structures, and highlights the properties and applications of photonic materials derived from block copolymers, colloid crystals, and microfabricated polymers. We conclude with a summary of current and future research efforts and opportunities in the development of polymer materials for photonic applications.

  5. Structural and electrical characterization of hybrid metal-polypyrrole nanowires

    OpenAIRE

    Gence, L.; Faniel, S.; Gustin, C.; S. Melinte; Bayot, V.; Callegari, V.; Reynes, O.; Demoustier-Champagne, S.

    2011-01-01

    We present here the synthesis and structural characterization of hybrid Au-polypyrrole-Au and Pt- polypyrrole-Au nanowires together with a study of their electrical properties from room-temperature down to very low temperature. A careful characterization of the metal-polymer interfaces by trans- mission electron microscopy revealed that the structure and mechanical strength of bottom and upper interfaces are very different. Variable temperature electrical transport measurements were performed...

  6. Epitaxy-enabled vapor-liquid-solid growth of tin-doped indium oxide nanowires with controlled orientations

    KAUST Repository

    Shen, Youde

    2014-08-13

    Controlling the morphology of nanowires in bottom-up synthesis and assembling them on planar substrates is of tremendous importance for device applications in electronics, photonics, sensing and energy conversion. To date, however, there remain challenges in reliably achieving these goals of orientation-controlled nanowire synthesis and assembly. Here we report that growth of planar, vertical and randomly oriented tin-doped indium oxide (ITO) nanowires can be realized on yttria-stabilized zirconia (YSZ) substrates via the epitaxy-assisted vapor-liquid-solid (VLS) mechanism, by simply regulating the growth conditions, in particular the growth temperature. This robust control on nanowire orientation is facilitated by the small lattice mismatch of 1.6% between ITO and YSZ. Further control of the orientation, symmetry and shape of the nanowires can be achieved by using YSZ substrates with (110) and (111), in addition to (100) surfaces. Based on these insights, we succeed in growing regular arrays of planar ITO nanowires from patterned catalyst nanoparticles. Overall, our discovery of unprecedented orientation control in ITO nanowires advances the general VLS synthesis, providing a robust epitaxy-based approach toward rational synthesis of nanowires. © 2014 American Chemical Society.

  7. Laser Zone Annealing - Accelerated Route to Self-Assembled Nanostructures

    Science.gov (United States)

    Majewski, Pawel; Yager, Kevin; Rahman, Atikur; Black, Charles

    We present Laser Zone Annealing - a novel technique of accelerated self-assembly of block copolymer thin films utilizing laser light. In our approach, the laser beam, focused to a narrow line, is rastered across the polymer film coated on the light-absorbing substrate, inducing rapid and highly localized temperature transients in the film. By coupling our method with soft-shear, we demonstrate monolithic alignment of various cylinder-forming block copolymers over extremely short timescales. We utilize the aligned block copolymer films as templates for inorganic nanomaterials pattering. After delivery of inorganic precursors via aqueous or gaseous route, the polymer matrix is ashed leading to extremely well-ordered arrays of inorganic, metallic or semiconducting nanowires. Subsequently, we demonstrate how more complex nanostructures can be created with LZA including multilayered nanomeshes with symmetries beyond the conventional motifs accessible by native block copolymers. We investigate a perspective use of the inorganic arrays as transparent conductors or chemical sensors and characterize their anisotropic electro-optical properties. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

  8. Indium Arsenide Nanowires

    DEFF Research Database (Denmark)

    Madsen, Morten Hannibal

    This thesis is about growth of Au-assisted and self-assisted InAs nanowires (NWs). The wires are synthesized using a solid source molecular beam epitaxy (MBE) system and characterized with several techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ...

  9. Aging of Organic Nanowires

    DEFF Research Database (Denmark)

    Balzer, Frank; Schiek, Manuela; Osadnik, Andreas;

    2012-01-01

    Organic semiconductors formed by epitaxial growth from small molecules such as the para-phenylenes or squaraines promise a vast application potential as the active ingredient in electric and optoelectronic devices. Their self-organization into organic nanowires or "nanofibers" adds a peculiar...

  10. Effective passivation of Ag nanowire-based flexible transparent conducting electrode by TiO2 nanoshell

    Science.gov (United States)

    Lee, Dong Geon; Lee, Dongjun; Yoo, Jin Sun; Lee, Sangwook; Jung, Hyun Suk

    2016-08-01

    Silver nanowire-based flexible transparent electrodes have critical problem, in spite of their excellent electrical and optical properties, that the electrical conductance and transparency degrade within several days in air because of oxidation of silver. To prevent the degradation of the silver nanowire, we encapsulated Ag-NWs with thin TiO2 barrier. Bar-coated silver nanowires on flexible polymer substrate were laminated at 120 °C, followed by atomic layer deposition of TiO2 nanoshell. With 20 nm of TiO2 nanoshells on silver nanowires, the transparent electrode keeps its electrical and optical properties over 2 months. Moreover, the TiO2-encapsulated silver nanowire-based transparent electrodes exhibit excellent bending durability.

  11. From 1D to 3D - macroscopic nanowire aerogel monoliths

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-07-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images, and digital photographs. See DOI: 10.1039/c6nr04429h

  12. Four 1-D metal-organic polymers self-assembled from semi-flexible benzimidazole-based ligand: Syntheses, structures and fluorescent properties

    Science.gov (United States)

    Zhou, Chun-lin; Wang, Shi-min; Liu, Sai-nan; Yu, Tian-tian; Li, Rui-ying; Xu, Hong; Liu, Zhong-yi; Sun, Huan; Cheng, Jia-jia; Li, Jin-peng; Hou, Hong-wei; Chang, Jun-biao

    2016-08-01

    Four one-dimensional (1-D) metal-organic polymers based on methylene-bis(1,1‧-benzimidazole)(mbbz), namely, {[Hg(mbbz)(SCN)2]·1/3H2O}n (1), [Co(mbbz)(Cl)2]n (2), {[Co(mbbz)(SO4)]·CH3OH}n (3) and {[Zn(mbbz)(SO4)]·CH3OH}n (4) have been successfully synthesized and structurally characterized. Single-crystal X-ray diffraction reveals that polymers 1 and 2 exhibit interesting 1-D double helical chain structures, while polymers 3 and 4 are 1-D double chain structures due to the bridging effect of mbbz ligands and sulfate anions. These polymers containing the mbbz-based ligand have a high degree of dependence on the corresponding counter anions. Furthermore, the fluorescence properties of the four polymers were also investigated in the solid state, showing the fluorescence signal changes in comparing with that of free ligand mbbz.

  13. Electric Conductivity of Phosphorus Nanowires

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Xiang; LI Hui; ZHANG Xue-Qing; LIEW Kim-Meow

    2009-01-01

    We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them,the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I - V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures.

  14. Formation of nanowires via single particle-triggered linear polymerization of solid-state aromatic molecules.

    Science.gov (United States)

    Horio, Akifumi; Sakurai, Tsuneaki; Lakshmi, G B V S; Kumar Avasthi, Devesh; Sugimoto, Masaki; Yamaki, Tetsuya; Seki, Shu

    2016-08-11

    Nanowires occupy a prestigious place in nanoelectronics, nanomechanics, and biomimetics. Although there are notable methods to grow nanowires via self-assembly, there is a key drawback in the need to find out the specific conditions appropriate for each system. In this sense, universal techniques to fabricate such nanowires from various organic materials have been sought for the continued progress of the related research field. Here we report one of the promising and facile methodologies to quantitatively produce nanowires with controlled geometrical parameters. In this method, referred to as "Single Particle-Triggered Linear Polymerization (STLiP)", organic thin films on a supporting substrate were irradiated with high-energy charged particles, accelerated by particle accelerators. Each particle penetrates from the top of the films to the substrate while gradually releasing kinetic energy along its trajectory (ion track), generating reactive intermediates such as radical species that eventually induce propagation reactions. The resulting polymerized products were integrated into nanowires with uniform diameter and length that can be isolated via development with appropriate organic solvents. Considering the widely applicable nature of STLiP to organic materials, the present technique opens a new door for access to a number of functional nanowires and their assembly. PMID:27355341

  15. Electrical characteristics and optoelectronic properties of metal-semiconductor-metal structure with zinc oxide nanowires across Au electrodes

    Institute of Scientific and Technical Information of China (English)

    Wang Ding-Qu; Zhou Zhao-Ying; Zhu Rong; Ye Xiong-Ying

    2008-01-01

    This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal-semiconductor-metal(MSM)structure by dielectrophoresis and studying on its electrical characteristics by using current-voltage(Ⅰ-Ⅴ)measurements.An electronic model with two back to back Schottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures.By fitting the measured Ⅰ-Ⅴ characteristics using the proposed model,the parameters of the Schottky contacts and the resistance of nanowires could be acquired.The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities.The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.

  16. Preparation and characterization of highly ordered NiO nanowire arrays by sol-gel template method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Highly ordered nickel monoxide (NiO) nanowire arrays were fabricated by sol-gel synthesis within the pores of anodic alumina membrane (AAM).Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) were used to characterize the topography and crystalloid structure of NiO nanowire arrays.The length and diameter of the NiO nanowires depended on the thickness of the AAM and the diameter of the pores.The results indicated that the NiO nanowires were uniformly assembled into the ordered nanopores of the AAM and paralleled to each other.Nickel monoxide nanotubes were also fabricated with the same method by changing the immersing time.This new method to prepare NiO nanowire arrays may be important from gas sensors to various engineering materials.

  17. Synthesis, assembly and device of 1-dimentional nanostructures

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Synthesis and assembly of 1-dimentional (1-D) nanostructures and measurement of their electrical and optical properties are very important in fabrication of nanodevices. Recent developments in this field are summarized in this review. The assembling methods can be divided into two classes: assembly using macroscopic field forces and microfluidic-assisted-template-integration. The former can assemble nanowires by controlling direction and intensity of electric or magnetic field, while the latter represents a general assembly strategy for any kind of 1-D nanostructures. The assembly of 1-D nanostructures will make it possible to fabricate nanosensors, nanolasers and nanoscale logic gate circuits for computation.

  18. Six Zn(II) and Cd(II) coordination polymers assembled from a similar binuclear building unit: tunable structures and luminescence properties.

    Science.gov (United States)

    Zhang, Liyan; Rong, Lulu; Hu, Guoli; Jin, Suo; Jia, Wei-Guo; Liu, Ji; Yuan, Guozan

    2015-04-21

    Six Zn(ii) and Cd(ii) coordination polymers were constructed by treating a 2-substituted 8-hydroxyquinolinate ligand containing a pyridyl group with zinc or cadmium salts, and characterized by a variety of techniques. Interestingly, based on a similar binuclear Zn(ii) or Cd(ii) building unit, the supramolecular structures of the six coordination polymers () exhibit an unprecedented structural diversification due to the different choices of metal salts. and represent a novel 2D framework containing 1D infinite right- and left-handed helical chains. and are 2D coordination frameworks based on binuclear Cd(ii) building units. For and , the L ligands can bridge binuclear building units forming a 1D infinite chain. Interestingly, the adjacent Cd2O2 planes of the 1D chain in are in parallel with each other, while the dihedral angle between the two Zn2O2 planes in is 83.43°. Photoluminescence properties revealed that the six coordination polymers exhibit redshifted emission maximum compared with the free ligand HL, which can be ascribed to an increased conformational rigidity and the fabrication of coplanar binuclear building units M2L2 in . Coordination polymers also display distinct fluorescence lifetimes and quantum yields because of their different metal centers and supramolecular structures.

  19. High-performance membrane-electrode assembly with an optimal polytetrafluoroethylene content for high-temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung;

    2016-01-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high...

  20. Heteronanostructure of Ag particle on titanate nanowire membrane with enhanced photocatalytic properties and bactericidal activities

    Energy Technology Data Exchange (ETDEWEB)

    Shang Lu; Li Bingjie [Department of Physics, Center for Optoelectronics Materials and Devices, and Key Laboratory of ATMMT, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Dong Wenjun, E-mail: wenjundong@zstu.edu.cn [Department of Physics, Center for Optoelectronics Materials and Devices, and Key Laboratory of ATMMT, Zhejiang Sci-Tech University, Hangzhou 310018 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Chen Benyong; Li Chaorong; Tang Weihua [Department of Physics, Center for Optoelectronics Materials and Devices, and Key Laboratory of ATMMT, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wang Ge, E-mail: gewang@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wu Jian [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029 (China); Ying Yibin, E-mail: ybying@zju.edu.cn [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029 (China)

    2010-06-15

    A novel seed induced method has been developed for syntheses of Ag particles on titanate nanowires, and then the heteronanostructured Ag/titanate nanowires were assembled into porous, flexible membranes. These titanate nanowires were about several hundreds micrometers in length and about 80 nm in diameter. The size of the Ag particle can be tuned within 300-700 nm. The pore size and thickness of the heteronanostructured membrane were easily controlled. An Ag/titanate nanowire membrane reactor has been developed to study the photocatalytic degradation of methamidophos in aqueous solution, and 87.0% of the methamidophos can be degraded in a concurrent filtration and photocatalytic oxidation process. The antibacterial activity was also investigated on the heteronanostructured membrane with UVA light (365 nm) irradiation, and a 99.99% satisfactory antibacterial effect on Escherichia coli was achieved.

  1. Heteronanostructure of Ag particle on titanate nanowire membrane with enhanced photocatalytic properties and bactericidal activities

    International Nuclear Information System (INIS)

    A novel seed induced method has been developed for syntheses of Ag particles on titanate nanowires, and then the heteronanostructured Ag/titanate nanowires were assembled into porous, flexible membranes. These titanate nanowires were about several hundreds micrometers in length and about 80 nm in diameter. The size of the Ag particle can be tuned within 300-700 nm. The pore size and thickness of the heteronanostructured membrane were easily controlled. An Ag/titanate nanowire membrane reactor has been developed to study the photocatalytic degradation of methamidophos in aqueous solution, and 87.0% of the methamidophos can be degraded in a concurrent filtration and photocatalytic oxidation process. The antibacterial activity was also investigated on the heteronanostructured membrane with UVA light (365 nm) irradiation, and a 99.99% satisfactory antibacterial effect on Escherichia coli was achieved.

  2. Nanowire liquid pumps

    Science.gov (United States)

    Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X.; Li, Ju

    2013-04-01

    The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ~10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability.

  3. Silicon nanowire transistors

    CERN Document Server

    Bindal, Ahmet

    2016-01-01

    This book describes the n and p-channel Silicon Nanowire Transistor (SNT) designs with single and dual-work functions, emphasizing low static and dynamic power consumption. The authors describe a process flow for fabrication and generate SPICE models for building various digital and analog circuits. These include an SRAM, a baseband spread spectrum transmitter, a neuron cell and a Field Programmable Gate Array (FPGA) platform in the digital domain, as well as high bandwidth single-stage and operational amplifiers, RF communication circuits in the analog domain, in order to show this technology’s true potential for the next generation VLSI. Describes Silicon Nanowire (SNW) Transistors, as vertically constructed MOS n and p-channel transistors, with low static and dynamic power consumption and small layout footprint; Targets System-on-Chip (SoC) design, supporting very high transistor count (ULSI), minimal power consumption requiring inexpensive substrates for packaging; Enables fabrication of different types...

  4. An Ultralong, Highly Oriented Nickel-Nanowire-Array Electrode Scaffold for High-Performance Compressible Pseudocapacitors.

    Science.gov (United States)

    Xu, Chao; Li, Ziheng; Yang, Cheng; Zou, Peichao; Xie, Binghe; Lin, Ziyin; Zhang, Zhexu; Li, Baohua; Kang, Feiyu; Wong, Ching-Ping

    2016-06-01

    Ultralong, highly oriented Ni nanowire arrays are used as the electrode scaffold to support metal-oxide- and conductive-polymer-based electrode materials with a high mass loading; the as-obtained asymmetric supercapacitor can be compressed by fourfold and exhibits superior energy and power densities with ultrahigh cycle stability. PMID:27062285

  5. Electrodeposited germanium nanowires.

    Science.gov (United States)

    Mahenderkar, Naveen K; Liu, Ying-Chau; Koza, Jakub A; Switzer, Jay A

    2014-09-23

    Germanium (Ge) is a group IV semiconductor with superior electronic properties compared with silicon, such as larger carrier mobilities and smaller effective masses. It is also a candidate anode material for lithium-ion batteries. Here, a simple, one-step method is introduced to electrodeposit dense arrays of Ge nanowires onto indium tin oxide (ITO) substrates from aqueous solution. The electrochemical reduction of ITO produces In nanoparticles that act as a reduction site for aqueous Ge(IV) species, and as a solvent for the crystallization of Ge nanowires. Nanowires deposited at 95 °C have an average diameter of 100 nm, whereas those deposited at room temperature have an average diameter of 35 nm. Both optical absorption and Raman spectroscopy suggest that the electrodeposited Ge is degenerate. The material has an indirect bandgap of 0.90-0.92 eV, compared with a value of 0.67 eV for bulk, intrinsic Ge. The blue shift is attributed to the Moss-Burstein effect, because the material is a p-type degenerate semiconductor. On the basis of the magnitude of the blue shift, the hole concentration is estimated to be 8 × 10(19) cm(-3). This corresponds to an In impurity concentration of about 0.2 atom %. The resistivity of the wires is estimated to be 4 × 10(-5) Ω·cm. The high conductivity of the wires should make them ideal for lithium-ion battery applications. PMID:25157832

  6. Quantum transport in semiconductor nanowires

    NARCIS (Netherlands)

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growt

  7. Controlled size, structure, and morphology of nanowires produced by single particle nano-fabrication technique (SPNT)

    International Nuclear Information System (INIS)

    Cross-linking reaction of the polymers was firstly promoted by charged particle irradiation to the thin films in the present study. Non-homogeneous cross-linking reaction in the polymers gives clear nanowires whose size, length, and number density are fairly controlled by selecting particles, molecular weights, etc. Electronic conductive nanowires were produced by the present technique, as well as achieving the formation of SiC ceramic nanowires by the combined processes of SPNT and subsequent sintering at ultra-high temperature. It is also demonstrated that the morphology of the final nanostructure is customized by appropriate selection of the ion fluence, combination of polymers, and the solvent employed for development. Octopus-like nanostructures consisting of a tangled hydrophilic polymer core and splayed hydrophobic polymer segments are successfully produced as an example of the process. The present technique provides universal feasibility for the formation of nanostructures based on 'any' polymer materials in which radiations induce crosslinking reactions. (author)

  8. Synthesis of a fullerene-based one-dimensional nanopolymer through topochemical transformation of the parent nanowire

    CERN Document Server

    Geng, Junfeng; Reid, David G; Skelton, Paul; Wheatley, Andrew E H; Solov'yov, Andrey V; Johnson, Brian F G

    2009-01-01

    Large-scale practical applications of fullerene (C60) in nanodevices could be significantly facilitated if the commercially-available micrometer-scale raw C60 powder were further processed into a one-dimensional (1D) nanowire-related polymer displaying covalent bonding as molecular interlinks and resembling traditional important conjugated polymers. However, there has been little study thus far in this area despite the abundant literature on fullerene. Here we report the synthesis and characterization of such a C60-based nanowire polymer, (-C60TMB-)n, where TMB=1,2,4-trimethylbenzene, which displays a well-defined crystalline structure, exceptionally large length-to-width ratio and excellent thermal stability. The material is prepared by first growing the corresponding nanowire through a solution phase of C60 followed by a topochemical polymerization reaction in the solid state. Gas chromatography, mass spectrometry and 13C nuclear magnetic resonance evidence is provided for the nature of the covalent bonding...

  9. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes....... With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid...

  10. High Efficient Photochromic WO3 polymer/1,10 DAD Self assembly Films Modified by Organic Molecules%高效率变色WO3多聚体/1,10-DAD自组装薄膜的制备

    Institute of Scientific and Technical Information of China (English)

    陈朝晖; 马颖; 姚建年

    2000-01-01

    A novel high efficient photochromic self assembly multilayered film has been fabricat ed from WO3 and 1,10 DAD solution using molecular deposition technique.The dependence of photochromic behavior on aggregation of WO3 in the WO3 polymer/1,10 DAD self assembly film was discussed in comparison with WO3/ 4,4'-BAMBp system.The results clearly show that organic molecules determine the charge density of the substrate,then affect the assembled structure of inorganic precursor and the stablility of the photo induced charge transfer complexes,and thus manipulate the structure and the photochromic properties of the films.

  11. Fabricating Electrochromic Thin Films Based on Metallo-Polymers Using Layer-by-Layer Self-Assembly: An Attractive Laboratory Experiment

    Science.gov (United States)

    Schott, Marco; Beck, Matthias; Winkler, Franziska; Lorrmann, Henning; Kurth, Dirk G.

    2015-01-01

    Metallo-supramolecular polyelectrolytes (MEPE) based on iron(II)-acetate and 1,4-bis(2,2':6',2?-terpyridin-4'-yl)benzene are assembled by layer-by-layer deposition on transparent electrode surfaces. When a potential is applied, the color of the film can be switched from blue to transparent. Due to the strong absorption and the fast switching…

  12. Supramolecular Organic Nanowires as Plasmonic Interconnects.

    Science.gov (United States)

    Armao, Joseph J; Domoto, Yuya; Umehara, Teruhiko; Maaloum, Mounir; Contal, Christophe; Fuks, Gad; Moulin, Emilie; Decher, Gero; Javahiraly, Nicolas; Giuseppone, Nicolas

    2016-02-23

    Metallic nanostructures are able to interact with an incident electromagnetic field at subwavelength scales by plasmon resonance which involves the collective oscillation of conduction electrons localized at their surfaces. Among several possible applications of this phenomenon, the theoretical prediction is that optical circuits connecting multiple plasmonic elements will surpass classical electronic circuits at nanoscale because of their much faster light-based information processing. However, the placement and coupling of metallic elements smaller than optical wavelengths currently remain a formidable challenge by top-down manipulations. Here, we show that organic supramolecular triarylamine nanowires of ≈1 nm in diameter are able to act as plasmonic waveguides. Their self-assembly into plasmonic interconnects between arrays of gold nanoparticles leads to the bottom-up construction of basic optical nanocircuits. When the resonance modes of these metallic nanoparticles are coupled through the organic nanowires, the optical conductivity of the plasmonic layer dramatically increases from 259 to 4271 Ω(-1)·cm(-1). We explain this effect by the coupling of a hot electron/hole pair in the nanoparticle antenna with the half-filled polaronic band of the organic nanowire. We also demonstrate that the whole hybrid system can be described by using the abstraction of the lumped circuit theory, with a far field optical response which depends on the number of interconnects. Overall, our supramolecular bottom-up approach opens the possibility to implement processable, soft, and low cost organic plasmonic interconnects into a large number of applications going from sensing to metamaterials and information technologies.

  13. Supramolecular Organic Nanowires as Plasmonic Interconnects.

    Science.gov (United States)

    Armao, Joseph J; Domoto, Yuya; Umehara, Teruhiko; Maaloum, Mounir; Contal, Christophe; Fuks, Gad; Moulin, Emilie; Decher, Gero; Javahiraly, Nicolas; Giuseppone, Nicolas

    2016-02-23

    Metallic nanostructures are able to interact with an incident electromagnetic field at subwavelength scales by plasmon resonance which involves the collective oscillation of conduction electrons localized at their surfaces. Among several possible applications of this phenomenon, the theoretical prediction is that optical circuits connecting multiple plasmonic elements will surpass classical electronic circuits at nanoscale because of their much faster light-based information processing. However, the placement and coupling of metallic elements smaller than optical wavelengths currently remain a formidable challenge by top-down manipulations. Here, we show that organic supramolecular triarylamine nanowires of ≈1 nm in diameter are able to act as plasmonic waveguides. Their self-assembly into plasmonic interconnects between arrays of gold nanoparticles leads to the bottom-up construction of basic optical nanocircuits. When the resonance modes of these metallic nanoparticles are coupled through the organic nanowires, the optical conductivity of the plasmonic layer dramatically increases from 259 to 4271 Ω(-1)·cm(-1). We explain this effect by the coupling of a hot electron/hole pair in the nanoparticle antenna with the half-filled polaronic band of the organic nanowire. We also demonstrate that the whole hybrid system can be described by using the abstraction of the lumped circuit theory, with a far field optical response which depends on the number of interconnects. Overall, our supramolecular bottom-up approach opens the possibility to implement processable, soft, and low cost organic plasmonic interconnects into a large number of applications going from sensing to metamaterials and information technologies. PMID:26814600

  14. Hard template synthesis of metal nanowires

    Directory of Open Access Journals (Sweden)

    Go eKawamura

    2014-11-01

    Full Text Available Metal nanowires (NWs have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

  15. Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells; Architectures hybrides auto-assemblees a base de systemes polyconjugues et de nanocristaux de semi-conducteurs pour le photovoltaique plastique

    Energy Technology Data Exchange (ETDEWEB)

    Girolamo, J. de

    2007-11-15

    This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

  16. Water-soluble light-emitting nanoparticles prepared by non-covalent bond self-assembly of a hydroxyl group functionalized oligo(p-phenyleneethynylene) with different water-soluble polymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Water-soluble light-emitting nanoparticles were prepared from hydroxyl group functionalized oligos(p-phenyleneethynylene) (OHOPEL) and water-soluble polymers(PEG,PAA,and PG) by non-covalent bond self-assembly.Their structure and optoelectronic properties were investigated through dynamic light scattering(DLS) ,UV and PL spectroscopy.The optical properties of OHOPEL-based water-soluble nanoparticles exhibited the same properties as that found in OHOPEL films,indicating the existence of interchain-aggregation of OHOPELs in the nanoparticles.OHOPEL-based nanoparticles prepared from conjugated oligomers show smaller size and lower dispersity than nanoparticles from conjugated polymers,which means that the structures of water-soluble nanoparticles are linked to the conjugated length.Furthermore,the OHOPEL/PG and OHOPEL/PAA systems produced smaller particles and lower polydispersity than the OHOPEL/PEG system,indicating that there may exist influence of the strength of non-covalent bonds on the size and degree of dispersity of the nanoparticles.

  17. Synthesis,M(o)ssbauer Spectra and Magnetic Properties of Quasi-One-Dimensional Fe3O4 Nanowires

    Institute of Scientific and Technical Information of China (English)

    薛德胜; 张丽英; 高存绪; 许雪飞; 桂安标

    2004-01-01

    Quasi-one-dimensional Fe3O4 nanowires in diameter of about 200nm were assembled into anodic aluminium oxide templates via electrodepositing and heat-treating processes. The nanowires have a polycrystalline spinel structure with a = 8.317A, and each nanowire is composed of fine Fe3O4 crystallites with size of about 30nm.The magnetic moments of Fe3 O4 crystallites in nanowires have a preferred orientation leaning to the wire axis but not parallel to the wire axis. Mossbauer spectra (MS) were used to verify the presence of Fe3 O4 further and the existence of superparamagnetic particles in nanowires. A perpendicular magnetic anisotropy was observed obviously. Temperature dependence of the magnetic moments (M-T) shows that the Verwey transition for the Fe3 O4 nanowires occurs at 50 K, and the behaviour of the M-T curve is different from that of other magnetite materials. These characteristic magnetic properties of Fe3 O4 nanowires are mainly due to the reduced dimension and the configuration of preferred orientation in the nanowires caused by the shape anisotropy.

  18. Polymer films

    Science.gov (United States)

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  19. Three luminescent d{sup 10} metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu{sup 2+} ion and nitrobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wei-Ping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China); Institute of Functional Materials, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science & Engineering, Zigong 643000 (China); Liu, Ping; Liang, Yu-Tong; Cui, Lin; Xi, Zheng-Ping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China); Wang, Yao-Yu, E-mail: wyaoyu@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China)

    2015-08-15

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL{sub 2}]{sub n} (1) and ([ML{sub 2}]·(H{sub 2}O)){sub n} (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu{sup 2+} ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed. - Graphical abstract: Three luminescent d{sup 10} metal coordination polymers with helical-layer based on 4-((2-methyl-1H-imidazol-1-yl)methyl)benzoic acid have been obtained. Compound 1 shows high selective detecting for Cu{sup 2+} ion in aqueous and nitrobenzene. - Highlights: • Three coordination polymers with chiral helical-layer have been obtained. • 1 Can luminescent detect Cu{sup 2+} ion in aqueous media and nitrobenzene. • Racemic mixture or mesomer compounds can be obtained by controlling the reaction conditions.

  20. ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates

    Directory of Open Access Journals (Sweden)

    Taylor Curtis

    2010-01-01

    Full Text Available Abstract Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20–80 nm in diameter, up to 6 μm in length, density <40 nm apart at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.