WorldWideScience

Sample records for single thin polymer

  1. Polymer surfaces, interfaces and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stamm, M [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany)

    1996-11-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs.

  2. Polymer surfaces, interfaces and thin films

    International Nuclear Information System (INIS)

    Stamm, M.

    1996-01-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs

  3. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  4. Thermal properties and stabilities of polymer thin films

    International Nuclear Information System (INIS)

    Kanaya, Toshiji; Kawashima, Kazuko; Inoue, Rintaro; Miyazaki, Tsukasa

    2009-01-01

    Recent extensive studies have revealed that polymer thin films showed very interesting but unusual thermal properties and stabilities. In the article we show that X-ray reflectivity and neutron reflectivity are very powerful tools to study the anomalous properties of polymer thin films. (author)

  5. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity...

  6. Azaisoindigo conjugated polymers for high performance n-type and ambipolar thin film transistor applications

    KAUST Repository

    Yue, Wan

    2016-09-28

    Two new alternating copolymers, PAIIDBT and PAIIDSe have been prepared by incorporating a highly electron deficient azaisoindigo core. The molecular structure and packing of the monomer is determined from the single crystal X-ray diffraction. Both polymers exhibit high EAs and highly planar polymer backbones. When polymers are used as the semiconducting channel for solution-processed thin film transistor application, good properties are observed. A–A type PAIIDBT exhibits unipolar electron mobility as high as 1.0 cm2 V−1 s−1, D–A type PAIIDSe exhibits ambipolar charge transport behavior with predominately electron mobility up to 0.5 cm2 V−1 s−1 and hole mobility to 0.2 cm2 V−1 s−1. The robustness of the extracted mobility values are also commented on in detail. Molecular orientation, thin film morphology and energetic disorder of both polymers are systematically investigated.

  7. Dynamic studies of nano-confined polymer thin films

    Science.gov (United States)

    Geng, Kun

    Polymer thin films with the film thickness (h0 ) below 100 nm often exhibit physical properties different from the bulk counterparts. In order to make the best use of polymer thin films in applications, it is important to understand the physical origins of these deviations. In this dissertation, I will investigate how different factors influence dynamic properties of polymer thin films upon nano-confinement, including glass transition temperature (Tg), effective viscosity (etaeff) and self-diffusion coefficient (D ). The first part of this dissertation concerns the impacts of the molecular weight (MW) and tacticity on the Tg's of nano-confined polymer films. Previous experiments showed that the Tg of polymer films could be depressed or increased as h0 decreases. While these observations are usually attributed to the effects of the interfaces, some experiments suggested that MW's and tacticities might also play a role. To understand the effects of these factors, the Tg's of silica-based poly(alpha-methyl styrene) (PalphaMS/SiOx) and poly(methyl methacrylate) (PMMA/SiOx) thin films were studied, and the results suggested that MW's and tacticities influence Tg in nontrivial ways. The second part concerns an effort to resolve the long-standing controversy about the correlation between different dynamics of polymer thin films upon nano-confinement. Firstly, I discuss the experimental results of Tg, D and etaeff of poly(isobutyl methacrylate) films supported by silica (PiBMA/SiOx). Both T g and D were found to be independent of h 0, but etaeff decreased with decreasing h 0. Since both D and etaeff describe transport phenomena known to depend on the local friction coefficient or equivalently the local viscosity, it is questionable why D and etaeff displayed seemingly inconsistent h 0 dependencies. We envisage the different h0 dependencies to be caused by Tg, D and etaeff being different functions of the local T g's (Tg,i) or viscosities (eta i). By assuming a three

  8. Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chapi, Sharanappa; Niranjana, M.; Devendrappa, H., E-mail: dehu2010@gmail.com [Department of Physics, Mangalore University, Mangalagangothri - 574 199 (India)

    2016-05-23

    Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence of compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.

  9. Scanning Angle Raman spectroscopy in polymer thin film characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Vy H.T. [Iowa State Univ., Ames, IA (United States)

    2015-12-19

    The focus of this thesis is the application of Raman spectroscopy for the characterization of thin polymer films. Chapter 1 provides background information and motivation, including the fundamentals of Raman spectroscopy for chemical analysis, scanning angle Raman scattering and scanning angle Raman scattering for applications in thin polymer film characterization. Chapter 2 represents a published manuscript that focuses on the application of scanning angle Raman spectroscopy for the analysis of submicron thin films with a description of methodology for measuring the film thickness and location of an interface between two polymer layers. Chapter 3 provides an outlook and future directions for the work outlined in this thesis. Appendix A, contains a published manuscript that outlines the use of Raman spectroscopy to aid in the synthesis of heterogeneous catalytic systems. Appendix B and C contain published manuscripts that set a foundation for the work presented in Chapter 2.

  10. Chemical solution deposition of YBCO thin film by different polymer additives

    International Nuclear Information System (INIS)

    Wang, W.T.; Li, G.; Pu, M.H.; Sun, R.P.; Zhou, H.M.; Zhang, Y.; Zhang, H.; Yang, Y.; Cheng, C.H.; Zhao, Y.

    2008-01-01

    A polymer-assisted chemical solution deposition approach has been proposed for the preparation of YBCO thin film. Different additives like PVB (polyvinyl butyral), PEG (polyethylene glycol) and PVP (polyvinylpyrrolidone) have been used to adjust the final viscosity of the precursor solution and thus the film formation. In this fluorine-free approach, YBCO has been deposited on single crystal substrates with metal acetates being starting materials. Biaxially textured YBCO thin films have been obtained. However, different additives lead to different microstructure. Dense, smooth and crack-free YBCO film prepared with PVB as additive yields sharp superconducting transition around T c = 90 K as well as high J c (0 T, 77 K) over 3 MA/cm 2

  11. Chemical solution deposition of YBCO thin film by different polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.T.; Li, G.; Pu, M.H.; Sun, R.P.; Zhou, H.M.; Zhang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Yang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia); Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, 2052 NSW (Australia)], E-mail: yzhao@swjtu.edu.cn

    2008-09-15

    A polymer-assisted chemical solution deposition approach has been proposed for the preparation of YBCO thin film. Different additives like PVB (polyvinyl butyral), PEG (polyethylene glycol) and PVP (polyvinylpyrrolidone) have been used to adjust the final viscosity of the precursor solution and thus the film formation. In this fluorine-free approach, YBCO has been deposited on single crystal substrates with metal acetates being starting materials. Biaxially textured YBCO thin films have been obtained. However, different additives lead to different microstructure. Dense, smooth and crack-free YBCO film prepared with PVB as additive yields sharp superconducting transition around T{sub c} = 90 K as well as high J{sub c} (0 T, 77 K) over 3 MA/cm{sup 2}.

  12. Enhanced magnetoelectric coupling in a composite multiferroic system via interposing a thin film polymer

    Science.gov (United States)

    Xiao, Zhuyun; Mohanchandra, Kotekar P.; Lo Conte, Roberto; Ty Karaba, C.; Schneider, J. D.; Chavez, Andres; Tiwari, Sidhant; Sohn, Hyunmin; Nowakowski, Mark E.; Scholl, Andreas; Tolbert, Sarah H.; Bokor, Jeffrey; Carman, Gregory P.; Candler, Rob N.

    2018-05-01

    Enhancing the magnetoelectric coupling in a strain-mediated multiferroic composite structure plays a vital role in controlling magnetism by electric fields. An enhancement of magnetoelastic coupling between ferroelectric single crystal (011)-cut [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈ 0.30) and ferromagnetic polycrystalline Ni thin film through an interposed benzocyclobutene polymer thin film is reported. A nearly twofold increase in sensitivity of remanent magnetization in the Ni thin film to an applied electric field is observed. This observation suggests a viable method of improving the magnetoelectric response in these composite multiferroic systems.

  13. Structures and Elastic Moduli of Polymer Nanocomposite Thin Films

    Science.gov (United States)

    Yuan, Hongyi; Karim, Alamgir; University of Akron Team

    2014-03-01

    Polymeric thin films generally possess unique mechanical and thermal properties due to confinement. In this study we investigated structures and elastic moduli of polymer nanocomposite thin films, which can potentially find wide applications in diverse areas such as in coating, permeation and separation. Conventional thermoplastics (PS, PMMA) and biopolymers (PLA, PCL) were chosen as polymer matrices. Various types of nanoparticles were used including nanoclay, fullerene and functionalized inorganic particles. Samples were prepared by solvent-mixing followed by spin-coating or flow-coating. Film structures were characterized using X-ray scattering and transmission electron microscopy. Elastic moduli were measured by strain-induced elastic buckling instability for mechanical measurements (SIEBIMM), and a strengthening effect was found in certain systems due to strong interaction between polymers and nanoparticles. The effects of polymer structure, nanoparticle addition and film thickness on elastic modulus will be discussed and compared with bulk materials.

  14. In-situ ATR-FTIR for characterization of thin biorelated polymer films

    International Nuclear Information System (INIS)

    Müller, M.; Torger, B.; Bittrich, E.; Kaul, E.; Ionov, L.; Uhlmann, P.; Stamm, M.

    2014-01-01

    We present and review in-situ-attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic data from thin biorelated polymer films useful for the modification and functionalization of polymer and inorganic materials and discuss their applications related to life sciences. A special ATR mirror attachment operated by the single-beam-sample-reference (SBSR) concept and housing a homebuilt thermostatable flow cell was used, which allows for appropriate background compensation and signal to noise ratio. ATR-FTIR data on the reactive deposition of dopamine on inorganic model surfaces are shown. Information on the structure and deposition pathway for such bioinspired melanin-like films is provided. ATR-FTIR data on thermosensitive polymer brushes of poly(N-isopropylacrylamide) (PNIPAAM) is then presented. The thermotropic hydration and hydrogen bonding behavior of PNIPAAM brush films is described. Finally, ATR-FTIR data on biorelated polyelectrolyte multilayers (PEM) are given together with details on PEM growth and detection. Applications of these latter films for biopassivation/activation and local drug delivery are addressed

  15. Conductivity behavior of very thin gold films ruptured by mass transport in photosensitive polymer film

    Energy Technology Data Exchange (ETDEWEB)

    Linde, Felix; Sekhar Yadavalli, Nataraja; Santer, Svetlana [Department of Experimental Physics, Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam (Germany)

    2013-12-16

    We report on conductivity behavior of very thin gold layer deposited on a photosensitive polymer film. Under irradiation with light interference pattern, the azobenzene containing photosensitive polymer film undergoes deformation at which topography follows a distribution of intensity, resulting in the formation of a surface relief grating. This process is accompanied by a change in the shape of the polymer surface from flat to sinusoidal together with a corresponding increase in surface area. The gold layer placed above deforms along with the polymer and ruptures at a strain of 4%. The rupturing is spatially well defined, occurring at the topographic maxima and minima resulting in periodic cracks across the whole irradiated area. We have shown that this periodic micro-rupturing of a thin metal film has no significant impact on the electrical conductivity of the films. We suggest a model to explain this phenomenon and support this by additional experiments where the conductivity is measured in a process when a single nanoscopic scratch is formed with an AFM tip. Our results indicate that in flexible electronic materials consisting of a polymer support and an integrated metal circuit, nano- and micro cracks do not alter significantly the behavior of the conductivity unless the metal is disrupted completely.

  16. Autophobicity and layering behavior of thin liquid-crystalline polymer films.

    NARCIS (Netherlands)

    Wielen, van der M.W.J.; Cohen Stuart, M.A.; Fleer, G.J.

    1998-01-01

    The stability against breaking-up of thin spin-coated films of liquid-crystalline polymers depends on the film thickness and annealing temperature. This study concerns side-chain liquid-crystalline polymers, based on alternating copolymers of maleic anhydride and mesogenic alkenes. The mesogenic

  17. Ultra-thin silicon/electro-optic polymer hybrid waveguide modulators

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Feng; Spring, Andrew M. [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Sato, Hiromu [Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Maeda, Daisuke; Ozawa, Masa-aki; Odoi, Keisuke [Nissan Chemical Industries, Ltd., 2-10-1 Tuboi Nishi, Funabashi, Chiba 274-8507 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492 (Japan); Yokoyama, Shiyoshi, E-mail: s-yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan)

    2015-09-21

    Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.

  18. Functional patterned coatings by thin polymer film dewetting.

    Science.gov (United States)

    Telford, Andrew M; Thickett, Stuart C; Neto, Chiara

    2017-12-01

    An approach for the fabrication of functional polymer surface coatings is introduced, where micro-scale structure and surface functionality are obtained by means of self-assembly mechanisms. We illustrate two main applications of micro-patterned polymer surfaces obtained through dewetting of bilayers of thin polymer films. By tuning the physical and chemical properties of the polymer bilayers, micro-patterned surface coatings could be produced that have applications both for the selective attachment and patterning of proteins and cells, with potential applications as biomaterials, and for the collection of water from the atmosphere. In all cases, the aim is to achieve functional coatings using approaches that are simple to realize, use low cost materials and are potentially scalable. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  20. Thin-film morphology of inkjet-printed single-droplet organic transistors using polarized Raman spectroscopy: effect of blending TIPS-pentacene with insulating polymer.

    Science.gov (United States)

    James, David T; Kjellander, B K Charlotte; Smaal, Wiljan T T; Gelinck, Gerwin H; Combe, Craig; McCulloch, Iain; Wilson, Richard; Burroughes, Jeremy H; Bradley, Donal D C; Kim, Ji-Seon

    2011-12-27

    We report thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) using angle-dependent polarized Raman spectroscopy. We show this to be an effective technique to determine the degree of molecular order as well as to spatially resolve the orientation of the conjugated backbones of the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) molecules. The addition of an insulating polymer, polystyrene (PS), does not disrupt the π-π stacking of the TIPS-Pentacene molecules. Blending in fact improves the uniformity of the molecular morphology and the active layer coverage within the device and reduces the variation in molecular orientation between polycrystalline domains. For OTFT performance, blending enhances the saturation mobility from 0.22 ± 0.05 cm(2)/(V·s) (TIPS-Pentacene) to 0.72 ± 0.17 cm(2)/(V·s) (TIPS-Pentacene:PS) in addition to improving the quality of the interface between TIPS-Pentacene and the gate dielectric in the channel, resulting in threshold voltages of ∼0 V and steep subthreshold slopes.

  1. Microscopy of thin polymer blend films of polystyrene and poly-n-butyl-methacrylate

    International Nuclear Information System (INIS)

    Schmitt, T.; Guttmann, P.; Schmahl, G.; Schmidt, O.; Schoenhense, G.; Mueller-Buschbaum, P.; Stamm, M.

    2000-01-01

    The structure of thin polymer blend films of polystyrene (PS) and poly-n-butyl-methacrylate (PnBMA) was examined with Transmission X-ray Microscopy (TXM), Scanning Force Microscopy (SFM), X-Ray Photoemission Electron Microscopy (X-PEEM) and Optical Microscopy (OM). Thin films were prepared by spin casting of a toluene solution of the polymer mixture onto silicon wafers retaining the native oxide. Depending on blend composition and annealing conditions smooth films with and without holes or films with well pronounced surface features (ribbons or islands) were produced. By TXM measurements a high lateral resolution study of the as cast and the annealed polymer blend samples was performed. The contrast in TXM is due to different absorption of x-radiation of the used polymers and due to variation in thickness. With X-PEEM the lateral distribution of the two polymers near the surface was mapped by employing the characteristic Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of the polymers. The TXM technique is a microscopic method integrating over the total film thickness, whereas the X-PEEM technique is a highly surface sensitive method. TXM and X-PEEM are therefore complementary methods which provide important information on the structure of thin polymer blend films additional to the standard techniques SFM and OM

  2. Mesoscopic layered structure in conducting polymer thin film fabricated by potential-programmed electropolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Fujitsuka, Mamoru (Div. of Molecular Engineering, Kyoto Univ. (Japan)); Nakahara, Reiko (Div. of Molecular Engineering, Kyoto Univ. (Japan)); Iyoda, Tomokazu (Div. of Molecular Engineering, Kyoto Univ. (Japan)); Shimidzu, Takeo (Div. of Molecular Engineering, Kyoto Univ. (Japan)); Tomita, Shigehisa (Toray Research Center Co., Ltd., Shiga (Japan)); Hatano, Yayoi (Toray Research Center Co., Ltd., Shiga (Japan)); Soeda, Fusami (Toray Research Center Co., Ltd., Shiga (Japan)); Ishitani, Akira (Toray Research Center Co., Ltd., Shiga (Japan)); Tsuchiya, Hajime (Nitto Technical Information Center Co., Ltd., Shimohozumi Ibaraki, Osaka (Japan)); Ohtani, Akira (Central Research Lab., Nitto Denko Co., Ltd., Shimohozumi Ibaraki, Osaka (Japan))

    1992-11-01

    Mesoscopic layered structures in conducting polymer thin films are fabricated by the potential-programmed electropolymerization method. High lateral quality in the layered structure is realized by the improvement of polymerization conditions, i.e., a mixture of pyrrole and bithiophene as monomers, a silicon single-crystal wafer as a working electrode and propylene carbonate as a solvent. SIMS depth profiling of the resulting layered films indicates a significant linear correlation between the electric charge passed and the thickness of the individual layers on a 100 A scale. (orig.)

  3. Performance of a polymer electrolyte membrane fuel cell with thin film catalyst electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Young Gab; Kim, Chang Soo; Peck, Dong Hyun; Shin, Dong Ryul [Korea Institute of Energy Research, Taejon (Korea, Republic of)

    1998-03-15

    In order to develop a kW-class polymer electrolyte membrane fuel cell (PEMFC), several electrodes have been fabricated by different catalyst layer preparation procedures and evaluated based on the cell performance. Conventional carbon paper and carbon cloth electrodes were fabricated using a ptfe-bonded Pt/C electrol catalyst by coating and rolling methods. Thin-film catalyst/ionomer composite layers were also formed on the membrane by direct coating and transfer printing techniques. The performance evaluation with catalyst layer preparation methods was carried out using a large or small electrode single cell. Conventional and thin film membrane and electrode assemblies (MEAs) with small electrode area showed a performance of 350 and 650 mA/cm{sup 2} at 0.6 V, respectively. The performance of direct coated thin film catalyst layer with 300 cm{sup 2} MEAs was higher than those of the conventional and transfer printing technique MEAs. The influence of some characteristic parameters of the thin film electrode on electrochemical performance was examined. Various other aspects of overall operation of PEMFC stacks were also discussed. (orig.)

  4. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

    KAUST Repository

    Oba, Tatsuya; Vacha, Martin

    2012-01-01

    We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films

  5. Optical characterizations of silver nanoprisms embedded in polymer thin film layers

    Science.gov (United States)

    Carlberg, Miriam; Pourcin, Florent; Margeat, Olivier; Le Rouzo, Judikael; Berginc, Gerard; Sauvage, Rose-Marie; Ackermann, Jorg; Escoubas, Ludovic

    2017-10-01

    The precise control of light-matter interaction has a wide range of applications and is currently driven by the use of nanoparticles (NPs) by the recent advances in nanotechnology. Taking advantage of the material, size, shape, and surrounding media dependence of the optical properties of plasmonic NPs, thin film layers with tunable optical properties are achieved. The NPs are synthesized by wet chemistry and embedded in a polyvinylpyrrolidone (PVP) polymer thin film layer. Spectrophotometer and spectroscopic ellipsometry measurements are coupled to finite-difference time domain numerical modeling to optically characterize the heterogeneous thin film layers. Silver nanoprisms of 10 to 50 nm edge size exhibit high absorption through the visible wavelength range. A simple optical model composed of a Cauchy law and a Lorentz law, accounting for the optical properties of the nonabsorbing polymer and the absorbing property of the nanoprisms, fits the spectroscopic ellipsometry measurements. Knowing the complex optical indices of heterogeneous thin film layers let us design layers of any optical properties.

  6. Dual-Input AND Gate From Single-Channel Thin-Film FET

    Science.gov (United States)

    Miranda, F. A.; Pinto, N. J.; Perez, R.; Mueller, C. H.

    2008-01-01

    A regio-regular poly(3-hexylthiophene) (RRP3HT) thin-film transistor having a split-gate architecture has been fabricated on a doped silicon/silicon nitride substrate and characterized. RRP3HT is a semiconducting polymer that has a carrier mobility and on/off ratio when used in a field effect transistor (FET) configuration. This commercially available polymer is very soluble in common organic solvents and is easily processed to form uniform thin films. The most important polymer-based device fabricated and studied is the FET, since it forms the building block in logic circuits and switches for active matrix (light-emitting-diode) (LED) displays, smart cards, and radio frequency identification (RFID) cards.

  7. Fabrication of flexible polymer dispersed liquid crystal films using conducting polymer thin films as the driving electrodes

    International Nuclear Information System (INIS)

    Kim, Yang-Bae; Park, Sucheol; Hong, Jin-Who

    2009-01-01

    Conducting polymers exhibit good mechanical and interfacial compatibility with plastic substrates. We prepared an optimized coating formulation based on poly(3,4-ethylenedioxythiophene) (PEDOT) and 3-(trimethoxysilyl)propyl acrylate and fabricated a transparent electrode on poly(ethylene terephthalate) (PET) substrate. The surface resistances and transmittance of the prepared thin films were 500-600 Ω/□ and 87% at 500 nm, respectively. To evaluate the performance of the conducting polymer electrode, we fabricated a five-layer flexible polymer-dispersed liquid crystal (PDLC) device as a PET-PEDOT-PDLC-PEDOT-PET flexible film. The prepared PDLC device exhibited a low driving voltage (15 VAC), high contrast ratio (60:1), and high transmittance in the ON state (60%), characteristics that are comparable with those of conventional PDLC film based on indium tin oxide electrodes. The fabrication of conducting polymer thin films as the driving electrodes in this study showed that such films can be used as a substitute for an indium tin oxide electrode, which further enhances the flexibility of PDLC film

  8. Slippage and nanorheology of thin liquid polymer films

    International Nuclear Information System (INIS)

    Bäumchen, Oliver; Fetzer, Renate; Klos, Mischa; Lessel, Matthias; Marquant, Ludovic; Hähl, Hendrik; Jacobs, Karin

    2012-01-01

    Thin liquid films on surfaces are part of our everyday life; they serve, e.g., as coatings or lubricants. The stability of a thin layer is governed by interfacial forces, described by the effective interface potential, and has been subject of many studies in recent decades. In recent years, the dynamics of thin liquid films has come into focus since results on the reduction of the glass transition temperature raised new questions on the behavior of especially polymeric liquids in confined geometries. The new focus was fired by theoretical models that proposed significant implication of the boundary condition at the solid/liquid interface on the dynamics of dewetting and the form of a liquid front. Our study reflects these recent developments and adds new experimental data to corroborate the theoretical models. To probe the solid/liquid boundary condition experimentally, different methods are possible, each bearing advantages and disadvantages, which will be discussed. Studying liquid flow on a variety of different substrates entails a view on the direct implications of the substrate. The experimental focus of this study is the variation of the polymer chain length; the results demonstrate that inter-chain entanglements and in particular their density close to the interface, originating from non-bulk conformations, govern the liquid slip of a polymer. (paper)

  9. Temperature- and thickness-dependent elastic moduli of polymer thin films

    Directory of Open Access Journals (Sweden)

    Ao Zhimin

    2011-01-01

    Full Text Available Abstract The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T and thickness (h-dependent elastic moduli of polymer thin films Ef(T,h is developed with verification by the reported experimental data on polystyrene (PS thin films. For the PS thin films on a passivated substrate, Ef(T,h decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*, at which thickness Ef(T,h deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ.

  10. Layered double hydroxides/polymer thin films grown by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R.; Matei, A.; Mitu, B.; Ionita, M.D.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest–Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Corobea, M.C. [National R. and S. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021, Bucharest (Romania)

    2013-09-30

    Due to their highly tunable properties, layered double hydroxides (LDHs) are an emerging class of the favorably layered crystals used for the preparation of multifunctional polymer/layered crystal nanocomposites. In contrast to cationic clay materials with negatively charge layers, LDHs are the only host lattices with positively charged layers (brucite-like), with interlayer exchangeable anions and intercalated water. In this work, the deposition of thin films of Mg and Al based LDH/polymers nanocomposites by laser techniques is reported. Matrix assisted pulsed laser evaporation was the method used for thin films deposition. The Mg–Al LDHs capability to act as a host for polymers and to produce hybrid LDH/polymer films has been investigated. Polyethylene glycol with different molecular mass compositions and ethylene glycol were used as polymers. The structure and surface morphology of the deposited LDH/polymers films were examined by X-ray diffraction, Fourier transform infra-red spectroscopy, atomic force microscopy and scanning electron microscopy. - Highlights: • Hybrid composites deposited by matrix assisted pulsed laser evaporation (MAPLE). • Mg–Al layered double hydroxides (LDH) and polyethylene glycol (PEG) are used. • Mixtures of PEG1450 and LDH were deposited by MAPLE. • Deposited thin films preserve the properties of the starting material. • The film wettability can be controlled by the amount of PEG.

  11. Organic thin film transistors and polymer light-emitting diodes patterned by polymer inking and stamping

    International Nuclear Information System (INIS)

    Li Dawen; Guo, L Jay

    2008-01-01

    To fully realize the advantages of organic flexible electronics, patterning is very important. In this paper we show that a purely additive patterning technique, termed polymer inking and stamping, can be used to pattern conductive polymer PEDOT and fabricate sub-micron channel length organic thin film transistors. In addition, we applied the technique to transfer a stack of metal/conjugated polymer in one step and fabricated working polymer light-emitting devices. Based on the polymer inking and stamping technique, a roll-to-roll printing for high throughput fabrication has been demonstrated. We investigated and explained the mechanism of this process based on the interfacial energy consideration and by using the finite element analysis. This technique can be further extended to transfer more complex stacked layer structures, which may benefit the research on patterning on flexible substrates

  12. Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

    Science.gov (United States)

    Jarad, Amer N.; Ibrahim, Kamarulazizi; Ahmed, Nasser M.

    2016-07-01

    In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10-5 (Ω.cm)-1, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  13. Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

    Energy Technology Data Exchange (ETDEWEB)

    Jarad, Amer N., E-mail: amer78malay@yahoo.com.my; Ibrahim, Kamarulazizi, E-mail: kamarul@usm.my; Ahmed, Nasser M., E-mail: nas-tiji@yahoo.com [Nano-optoelectronic Research and Technology Laboratory School of physics, University of Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2016-07-06

    In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10{sup −5} (Ω.cm){sup −1}, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  14. Performance of a Polymer Flood with Shear-Thinning Fluid in Heterogeneous Layered Systems with Crossflow

    Directory of Open Access Journals (Sweden)

    Kun Sang Lee

    2011-08-01

    Full Text Available Assessment of the potential of a polymer flood for mobility control requires an accurate model on the viscosities of displacement fluids involved in the process. Because most polymers used in EOR exhibit shear-thinning behavior, the effective viscosity of a polymer solution is a highly nonlinear function of shear rate. A reservoir simulator including the model for the shear-rate dependence of viscosity was used to investigate shear-thinning effects of polymer solution on the performance of the layered reservoir in a five-spot pattern operating under polymer flood followed by waterflood. The model can be used as a quantitative tool to evaluate the comparative studies of different polymer flooding scenarios with respect to shear-rate dependence of fluids’ viscosities. Results of cumulative oil recovery and water-oil ratio are presented for parameters of shear-rate dependencies, permeability heterogeneity, and crossflow. The results of this work have proven the importance of taking non-Newtonian behavior of polymer solution into account for the successful evaluation of polymer flood processes. Horizontal and vertical permeabilities of each layer are shown to impact the predicted performance substantially. In reservoirs with a severe permeability contrast between horizontal layers, decrease in oil recovery and sudden increase in WOR are obtained by the low sweep efficiency and early water breakthrough through highly permeable layer, especially for shear-thinning fluids. An increase in the degree of crossflow resulting from sufficient vertical permeability is responsible for the enhanced sweep of the low permeability layers, which results in increased oil recovery. It was observed that a thinning fluid coefficient would increase injectivity significantly from simulations with various injection rates. A thorough understanding of polymer rheology in the reservoir and accurate numerical modeling are of fundamental importance for the exact estimation

  15. Laser welding of thin polymer films to container substrates for aseptic packaging

    Science.gov (United States)

    Brown, N.; Kerr, D.; Jackson, M. R.; Parkin, R. M.

    2000-03-01

    Keyhole laser welding of polymers is a subject well covered and researched, but relatively little information exists regarding the welding of thin polymer films, particularly to a heavier substrate. This paper presents the design of a suitable test apparatus for laser welding thin film to a heavier substrate, and shows the results of an investigation into the feasibility of laser welding multi-layer polymer film lids to tubs for the manufacture of aseptic food containers. A consistent weld, free from defects, is the key to process success. Typical welding defects have been synthesised in order to investigate, and consequently remove, their cause. The result is a reliable welding method based on even film clamping. With careful attention to machine design, a seal of high mechanical strength and chemical integrity is possible.

  16. Programmed Switching of Single Polymer Conformation on DNA Origami

    DEFF Research Database (Denmark)

    Krissanaprasit, Abhichart; Madsen, Mikael; Knudsen, Jakob Bach

    2016-01-01

    -molecule conjugated polymer. The polymer is functionalized with short single-stranded (ss) DNA strands that extend from the backbone of the polymer and serve as handles. The DNA polymer conjugate can be aligned on DNA origami in three well-defined geometries (straight line, left-turned, and right-turned pattern......) by DNA hybridization directed by single-stranded guiding strands and ssDNA tracks extending from the origami surface and polymer handle. We demonstrate switching of a conjugated organic polymer conformation between left- and right-turned conformations of the polymer on DNA origami based on toehold...

  17. Second harmonic generation from corona-poled polymer thin films ...

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... thin films of Y-shape chromophore with different isolation groups. MUKESH P JOSHI1 ... Pramana – J. Phys., Vol. 82, No. ... C. The main advantage of the Y shape is the stability similar to linear polymer and a processing ability ...

  18. Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter

    International Nuclear Information System (INIS)

    Druffel, Thad; Geng Kebin; Grulke, Eric

    2006-01-01

    Thin-film filters on optical components have been in use for decades and, for those industries utilizing a polymer substrate, the mismatch in mechanical behaviour has caused problems. Surface damage including scratches and cracks induces haze on the optical filter, reducing the transmission of the optical article. An in-mold anti-reflective (AR) filter incorporating 1/4-wavelength thin films based on a polymer nanocomposite is outlined here and compared with a traditional vacuum deposition AR coating. Nanoindentation and nanoscratch techniques are used to evaluate the mechanical properties of the thin films. Scanning electron microscopy (SEM) images of the resulting indentations and scratches are then compared to the force deflection curves to further explain the phenomena. The traditional coatings fractured by brittle mechanisms during testing, increasing the area of failure, whereas the polymer nanocomposite gave ductile failure with less surface damage

  19. Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter.

    Science.gov (United States)

    Druffel, Thad; Geng, Kebin; Grulke, Eric

    2006-07-28

    Thin-film filters on optical components have been in use for decades and, for those industries utilizing a polymer substrate, the mismatch in mechanical behaviour has caused problems. Surface damage including scratches and cracks induces haze on the optical filter, reducing the transmission of the optical article. An in-mold anti-reflective (AR) filter incorporating 1/4-wavelength thin films based on a polymer nanocomposite is outlined here and compared with a traditional vacuum deposition AR coating. Nanoindentation and nanoscratch techniques are used to evaluate the mechanical properties of the thin films. Scanning electron microscopy (SEM) images of the resulting indentations and scratches are then compared to the force deflection curves to further explain the phenomena. The traditional coatings fractured by brittle mechanisms during testing, increasing the area of failure, whereas the polymer nanocomposite gave ductile failure with less surface damage.

  20. Structuring of thin-film polymer mixtures upon solvent evaporation

    NARCIS (Netherlands)

    Schaefer, C.; Michels, J.J.; van der Schoot, P.P.A.M.

    2016-01-01

    We theoretically study the impact of solvent evaporation on the dynamics of isothermal phase separation of ternary polymer solutions in thin films. In the early stages we obtain a spinodal length scale that decreases with time under the influence of ongoing evaporation. After that rapid demixing

  1. Structuring of Thin-Film Polymer Mixtures upon Solvent Evaporation

    NARCIS (Netherlands)

    Schaefer, C.; Michels, J. J.; van der Schoot, P.

    2016-01-01

    We theoretically study the impact of solvent evaporation on the dynamics of isothermal phase separation of ternary polymer solutions in thin films. In the early stages we obtain a spinodal length scale that decreases with time under the influence of ongoing evaporation. After that rapid demixing

  2. The influence of polymer architectures on the dewetting behavior of thin polymer films: from linear chains to ring chains.

    Science.gov (United States)

    Wang, Lina; Xu, Lin; Liu, Binyuan; Shi, Tongfei; Jiang, Shichun; An, Lijia

    2017-05-03

    The dewetting behavior of ring polystyrene (RPS) film and linear polystyrene (LPS) film on silanized Si substrates with different grafting densities and PDMS substrate was investigated. Results showed that polymer architectures greatly influenced the dewetting behavior of the thin polymer film. On the silanized Si substrate with 69% grafting density, RPS chains exhibited stronger adsorption compared with LPS chains, and as a result the wetting layer formed more easily. For LPS films, with a decreased annealing temperature, the stability of the polymer film changed from non-slip dewetting via apparent slip dewetting to apparently stable. However, for RPS films, the polymer film stability switched from apparent slip dewetting to apparently stable. On the silanized Si substrate with 94% grafting density, the chain adsorption became weaker and the dewetting processes were faster than that on the substrate with 69% grafting density at the same experimental temperature for both the LPS and RPS films. Moreover, on the PDMS substrate, LPS films always showed non-slip dewetting, while the dewetting kinetics of RPS films switched from non-slip dewetting to slip dewetting behaviour. Forming the wetting layer strongly influenced the stability and dewetting behavior of the thin polymer films.

  3. Dynamics in thin folded polymer films

    Science.gov (United States)

    Croll, Andrew; Rozairo, Damith

    Origami and Kirigami inspired structures depend on a complex interplay between geometry and material properties. While clearly important to the overall function, very little attention has focused on how extreme curvatures and singularities in real materials influence the overall dynamic behaviour of folded structures. In this work we use a set of three polymer thin films in order to closely examine the interaction of material and geometry. Specifically, we use polydimethylsiloxane (PDMS), polystyrene (PS) and polycarbonate (PC) thin films which we subject to loading in several model geometries of varying complexity. Depending on the material, vastly different responses are noted in our experiments; D-cones can annihilate, cut or lead to a crumpling cascade when pushed through a film. Remarkably, order can be generated with additional perturbation. Finally, the role of adhesion in complex folded structures can be addressed. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

  4. The effects of polymer molecular weight on filament thinning and drop breakup in microchannels

    International Nuclear Information System (INIS)

    Arratia, P E; Cramer, L-A; Gollub, J P; Durian, D J

    2009-01-01

    We investigate the effects of fluid elasticity on the dynamics of filament thinning and drop breakup processes in a cross-slot microchannel. Elasticity effects are examined using dilute aqueous polymeric solutions of molecular weight (MW) ranging from 1.5x10 3 to 1.8x10 7 . Results for polymeric fluids are compared to those for a viscous Newtonian fluid. The shearing or continuous phase that induces breakup is mineral oil. All fluids possess similar shear-viscosity (∼0.2 Pa s) so that the viscosity ratio between the oil and aqueous phases is close to unity. Measurements of filament thickness as a function of time show different thinning behavior for the different aqueous fluids. For Newtonian fluids, the thinning process shows a single exponential decay of the filament thickness. For low MW fluids (10 3 , 10 4 and 10 5 ), the thinning process also shows a single exponential decay, but with a decay rate that is slower than for the Newtonian fluid. The decay time increases with polymer MW. For high MW (10 6 and 10 7 ) fluids, the initial exponential decay crosses over to a second exponential decay in which elastic stresses are important. We show that the decay rate of the filament thickness in this exponential decay regime can be used to measure the steady extensional viscosity of the fluids. At late times, all fluids cross over to an algebraic decay which is driven mainly by surface tension.

  5. Synthesis and organisation of poly-substituted porphyrins in thin films for the elaboration of a highly conjugated 2D polymer

    International Nuclear Information System (INIS)

    Da Cruz, Fernande

    1997-01-01

    This research thesis addresses the production and characterization of organic thin layers for the elaboration of a wholly conjugated bi-dimensional polymer. The author first reports the synthesis of molecules belonging to the substituted porphyrin family substituted by reactive functions (acetylenic and thiophene functions). He reports how these molecules are organised under the form of a plane paving by using the Langmuir-Blodgett (LB) technique and self-assembly. It has been possible to obtain steady and organised LB films from one the synthesized porphyrins. A new method of organisation based on self-assembly has been developed, and allowed polymerizable organised porphyrin single layers to be obtained. This opens a promising way to the production of the bi-dimensional polymer. Thin films have been characterized by UV-visible spectrophotometry, IR spectrometry, X-ray diffraction, and linear dichroism [fr

  6. Control of polymer-packing orientation in thin films through synthetic tailoring of backbone coplanarity

    KAUST Repository

    Chen, Mark S.

    2013-10-22

    Controlling solid-state order of π-conjugated polymers through macromolecular design is essential for achieving high electronic device performance; yet, it remains a challenge, especially with respect to polymer-packing orientation. Our work investigates the influence of backbone coplanarity on a polymer\\'s preference to pack face-on or edge-on relative to the substrate. Isoindigo-based polymers were synthesized with increasing planarity by systematically substituting thiophenes for phenyl rings in the acceptor comonomer. This increasing backbone coplanarity, supported by density functional theory (DFT) calculations of representative trimers, leads to the narrowing of polymer band gaps as characterized by ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy and cyclic voltammetry. Among the polymers studied, regiosymmetric II and TII polymers exhibited the highest hole mobilities in organic field-effect transistors (OFETs), while in organic photovoltaics (OPVs), TBII polymers that display intermediate levels of planarity provided the highest power conversion efficiencies. Upon thin-film analysis by atomic force microscropy (AFM) and grazing-incidence X-ray diffraction (GIXD), we discovered that polymer-packing orientation could be controlled by tuning polymer planarity and solubility. Highly soluble, planar polymers favor face-on orientation in thin films while the less soluble, nonplanar polymers favor an edge-on orientation. This study advances our fundamental understanding of how polymer structure influences nanostructural order and reveals a new synthetic strategy for the design of semiconducting materials with rationally engineered solid-state properties. © 2013 American Chemical Society.

  7. Correlation of morphology and barrier properties of thin microwave plasma polymer films on metal substrate

    International Nuclear Information System (INIS)

    Barranco, V.; Carpentier, J.; Grundmeier, G.

    2004-01-01

    The barrier properties of thin model organosilicon plasma polymers layers on iron are characterised by means of electrochemical impedance spectroscopy (EIS). Tailored thin plasma polymers of controlled morphology and chemical composition were deposited from a microwave discharge. By the analysis of the obtained impedance diagrams, the evolution of the water uptake φ, coating resistance and polymer capacitance with immersion time were monitored and the diffusion coefficients of the water through the films were calculated. The impedance data correlated well with the chemical structure and morphology of the plasma polymer films with a thickness of less than 100 nm. The composition of the films were determined by means of infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The morphology of the plasma polymer surface and the interface between the plasma polymer and the metal were characterised using atomic force microscopy (AFM). It could be shown that, at higher pressure, the film roughness increases which is probably due to the adsorption of plasma polymer nanoparticles formed in the plasma bulk and the faster film growth. This leads to voids with a size of a few tens of nanometers at the polymer/metal interface. The film roughness increases from the interface to the outer surface of the film. By lowering the pressure and thereby slowing the deposition rate, the plasma polymers perfectly imitate the substrate topography and lead to an excellent blocking of the metal surface. Moreover, the ratio of siloxane bonds to methyl-silyl groups increases which implies that the crosslink density is higher at lower deposition rate. The EIS data consistently showed higher coating resistance as well as lower interfacial capacitance values and a better stability over time for the film deposited at slower pressure. The diffusion coefficient of water in thin and ultra-thin plasma

  8. Single clay sheets inside electrospun polymer nanofibers

    Science.gov (United States)

    Sun, Zhaohui

    2005-03-01

    Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

  9. Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

    Science.gov (United States)

    Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

    2017-01-18

    Bandgap engineering of kesterite Cu 2 Zn(Sn, Ge)(S, Se) 4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films with tunable bandgap. The bandgap of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films exhibits a hall coefficient of +137 cm 3 /C. The resistivity, concentration and carrier mobility of the Cu 2 ZnSn(S, Se) 4 thin film are 3.17 ohm·cm, 4.5 × 10 16 cm -3 , and 43 cm 2 /(V·S) at room temperature, respectively. Moreover, the Cu 2 ZnSn(S, Se) 4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  10. Numerical simulations of electrohydrodynamic evolution of thin polymer films

    Science.gov (United States)

    Borglum, Joshua Christopher

    Recently developed needleless electrospinning and electrolithography are two successful techniques that have been utilized extensively for low-cost, scalable, and continuous nano-fabrication. Rational understanding of the electrohydrodynamic principles underneath these nano-manufacturing methods is crucial to fabrication of continuous nanofibers and patterned thin films. This research project is to formulate robust, high-efficiency finite-difference Fourier spectral methods to simulate the electrohydrodynamic evolution of thin polymer films. Two thin-film models were considered and refined. The first was based on reduced lubrication theory; the second further took into account the effect of solvent drying and dewetting of the substrate. Fast Fourier Transform (FFT) based spectral method was integrated into the finite-difference algorithms for fast, accurately solving the governing nonlinear partial differential equations. The present methods have been used to examine the dependencies of the evolving surface features of the thin films upon the model parameters. The present study can be used for fast, controllable nanofabrication.

  11. Thin aligned organic polymer films for liquid crystal devices

    International Nuclear Information System (INIS)

    Foster, Kathryn Ellen

    1997-01-01

    This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation. (author)

  12. Investigation of thin polymer layers for biosensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Saftics, András; Agócs, Emil [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Fodor, Bálint [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Doctoral School of Physics, Faculty of Science, University of Pécs, 7624 Pécs, Ifjúság útja 6 (Hungary); Patkó, Dániel; Petrik, Péter [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Doctoral School of Molecular- and Nanotechnologies, Faculty of Information Technology, University of Pannonia, H-8200 Egyetem u.10, Veszprém (Hungary); Kolari, Kai; Aalto, Timo [VTT Technical Research Centre of Finland, PL 1000, Tietotie 3, 02044 Espoo (Finland); Fürjes, Péter [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Horvath, Robert [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Doctoral School of Molecular- and Nanotechnologies, Faculty of Information Technology, University of Pannonia, H-8200 Egyetem u.10, Veszprém (Hungary); Kurunczi, Sándor, E-mail: kurunczi.sandor@ttk.mta.hu [Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences–H-1121 Budapest (Hungary); Doctoral School of Molecular- and Nanotechnologies, Faculty of Information Technology, University of Pannonia, H-8200 Egyetem u.10, Veszprém (Hungary)

    2013-09-15

    Novel biosensors made of polymers may offer advantages over conventional technology such as possibility of mass production and tunability of the material properties. With the ongoing work on the polymer photonic chip fabrication in our project, simple model samples were tested parallel for future immobilization and accessing conditions for applications in typical aqueous buffers. The model samples consist of a thin, high refractive index polyimide film on top of TEOS on Si wafer. These model samples were measured by in situ spectroscopic ellipsometry using different aqueous buffers. The experiments revealed a high drift in aqueous solutions; the drift in the ellipsometric parameters (delta, psi) can be evaluated and presented as changes in thickness and refractive index of the polyimide layer. The first molecular layer of immobilization is based on polyethyleneimine (PEI). The signal for the PEI adsorption was detected on a stable baseline, only after a long conditioning. The stability of polyimide films in aqueous buffer solutions should be improved toward the real biosensor application. Preliminary results are shown on the possibilities to protect the polyimide. Optical Waveguide Lightmode Spectroscopy (OWLS) has been used to demonstrate the shielding effect of the thin TiO{sub 2} adlayer in biosensor applications.

  13. TiO2 thin-films on polymer substrates and their photocatalytic activity

    International Nuclear Information System (INIS)

    Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

    2006-01-01

    We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

  14. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2015-10-01

    Full Text Available Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO1, (PPy/ErGO1, (PAni/GO1 and (PPy/GO1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g−1 as compared with constituents (∼70 F g−1 at discharge current density of 0.3 A g−1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting and conducting polymers (semiconducting backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (reactivity of surface ion

  15. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sanju, E-mail: sanju.gupta@wku.edu; Price, Carson [Department of Physics and Astronomy, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-3576 (United States)

    2015-10-15

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine

  16. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Science.gov (United States)

    Gupta, Sanju; Price, Carson

    2015-10-01

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO)1, (PPy/ErGO)1, (PAni/GO)1 and (PPy/GO)1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g-1 as compared with constituents (˜70 F g-1) at discharge current density of 0.3 A g-1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites

  17. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    McAnally, Gerard David

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm -1 ) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are presented. A new band in the spectrum (1131 cm -1 ) is assigned to a complex vibration using a density functional calculation. Depth profiling through a polymer film on to the silver layer showed the SERS signals arise from the silver surface only. The profiles show the effects of refraction on the beam, and the adverse affect on the depth resolution. Silver films were used to obtain SERS spectra from a 40 nm thin-film coating on PET, without interference from the PET layer. The use of an azo dye probe as a marker to detect the coating is described. Finally, a novel method for the synthesis of a SERS-active vinyl-benzotriazole monomer is reported. The monomer was incorporated into a thin-film coating and the SERS spectrum obtained from the polymer. (author)

  18. Effect of Chain Conformation on the Single-Molecule Melting Force in Polymer Single Crystals: Steered Molecular Dynamics Simulations Study.

    Science.gov (United States)

    Feng, Wei; Wang, Zhigang; Zhang, Wenke

    2017-02-28

    Understanding the relationship between polymer chain conformation as well as the chain composition within the single crystal and the mechanical properties of the corresponding single polymer chain will facilitate the rational design of high performance polymer materials. Here three model systems of polymer single crystals, namely poly(ethylene oxide) (PEO), polyethylene (PE), and nylon-66 (PA66) have been chosen to study the effects of chain conformation, helical (PEO) versus planar zigzag conformation (PE, PA66), and chain composition (PE versus PA66) on the mechanical properties of a single polymer chain. To do that, steered molecular dynamics simulations were performed on those polymer single crystals by pulling individual polymer chains out of the crystals. Our results show that the patterns of force-extension curve as well as the chain moving mode are closely related to the conformation of the polymer chain in the single crystal. In addition, hydrogen bonds can enhance greatly the force required to stretch the polymer chain out of the single crystal. The dynamic breaking and reformation of multivalent hydrogen bonds have been observed for the first time in PA66 at the single molecule level.

  19. All-organic polymer-dispersed liquid crystal light-valves integrated with electroactive anthraquinone-2-sulfonate-doped polypyrrole thin films as driving electrodes

    International Nuclear Information System (INIS)

    Wang, Pen-Cheng; Yu, Jing-Yu; Li, Kuan-Hsun

    2011-01-01

    Highlights: → Fabrication of flexible semi-transparent all-polymer electrodes under ambient conditions without using a CVD system. → Characterization of the above electrodes based on anthraquinone-2-sulfonate-doped polypyrrole thin films. → Demonstration of all-organic liquid crystal light-valves with polypyrrole thin films as the driving electrodes. - Abstract: All-organic PDLC (polymer-dispersed liquid crystal) light-valves using all-polymer conductive substrates containing thin films of polypyrrole doped with anthraquinone-2-sulfonate (AQSA - ) as the driving electrodes were fabricated in this study. The all-polymer conductive substrates were prepared under ambient conditions by in situ depositing polypyrrole thin films on blank flexible poly(ethylene terephthalate), or PET, substrates from aqueous media in which oxidative polymerization of pyrrole was taking place. The obtained flexible all-polymer conductive substrates were semi-transparent with cohesive coatings of AQSA - doped polypyrrole thin films (thickness ∼55 nm). The all-polymer flexible conductive substrates had sheet resistivity ∼40 kΩ □ -1 and T% transparency against air ∼78% at 600 nm. The light-valves fabricated using the above all-polymer conductive substrates showed ∼50% transparency against air at 600 nm when 4 V μm -1 electric field was applied.

  20. Response of single polymers to localized step strains

    NARCIS (Netherlands)

    Panja, D.

    2009-01-01

    In this paper, the response of single three-dimensional phantom and self-avoiding polymers to localized step strains are studied for two cases in the absence of hydrodynamic interactions: (i) Polymers tethered at one end with the strain created at the point of tether, and (ii) free polymers with the

  1. Polymer Thin Film Stabilization.

    Science.gov (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.

    1998-03-01

    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  2. Polymer thin film as coating layer to prevent corrosion of metal/metal oxide film

    Science.gov (United States)

    Sarkar, Suman; Kundu, Sarathi

    2018-04-01

    Thin film of polymer is used as coating layer and the corrosion of metal/metal oxide layer is studied with the variation of the thickness of the coating layer. The thin layer of polystyrene is fabricated using spin coating method on copper oxide (CuO) film which is deposited on glass substrate using DC magnetron sputtering technique. Thickness of the polystyrene and the CuO layers are determined using X-ray reflectivity (XRR) technique. CuO thin films coated with the polystyrene layer are exposed to acetic acid (2.5 v/v% aqueous CH3COOH solution) environments and are subsequently analyzed using UV-Vis spectroscopy and atomic force microscopy (AFM). Surface morphology of the film before and after interaction with the acidic environment is determined using AFM. Results obtained from the XRR and UV-Vis spectroscopy confirm that the thin film of polystyrene acts as an anticorrosion coating layer and the strength of the coating depends upon the polymer layer thickness at a constant acid concentration.

  3. Lattice cluster theory for dense, thin polymer films.

    Science.gov (United States)

    Freed, Karl F

    2015-04-07

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L - 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential "transport" constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends.

  4. Lattice cluster theory for dense, thin polymer films

    International Nuclear Information System (INIS)

    Freed, Karl F.

    2015-01-01

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L − 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential “transport” constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends

  5. Confinement Effects on Host Chain Dynamics in Polymer Nanocomposite Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle J. [Department; Glynos, Emmanouil [Department; Maroulas, Serafeim-Dionysios [Department; Narayanan, Suresh [Advanced; Sakellariou, Georgios [Department; Green, Peter F. [Department; National

    2017-09-07

    Incorporating nanoparticles (NPs) within a polymer host to create polymer nanocomposites (PNCs) while having the effect of increasing the functionality (e.g., sensing, energy conversion) of these materials influences other properties. One challenge is to understand the effects of nanoparticles on the viscosity of nanoscale thick polymer films. A new mechanism that contributes to an enhancement of the viscosity of nanoscale thick polymer/nanoparticle films is identified. We show that while the viscosities of neat homopolymer poly(2-vinylpyridine) (P2VP) films as thin as 50 nm remained the same as the bulk, polymer/nanoparticle films containing P2VP brush-coated gold NPs, spaced 50 nm apart, exhibited unprecedented increases in viscosities of over an order of magnitude. For thicker films or more widely separated NPs, the chain dynamics and viscosities were comparable to the bulk values. These results - NP proximities and suppression of their dynamics - suggest a new mechanism by which the viscosities of polymeric liquids could be controlled for nanoscale applications.

  6. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech; Furchner, Andreas; Ghanem, Bader; Ma, Xiao-Hua; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  7. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech

    2017-10-12

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers\\' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  8. PRODUCTION OF HIGHER STRENGTH THIN WALLED GLOW DISCHARGE POLYMER SHELLS FOR CRYOGENIC EXPERIMENTS AT OMEGA

    International Nuclear Information System (INIS)

    NIKROO, A; CZECHOWICZ, DG; CASTILLO, ER; PONTELANDOLFO, JM

    2002-01-01

    OAK A271 PRODUCTION OF HIGHER STRENGTH THIN WALLED GLOW DISCHARGE POLYMER SHELLS FOR CRYOGENIC EXPERIMENTS AT OMEGA. Thin walled polymer shells are needed for OMEGA cryogenic laser experiments. These capsules need to be about 900 (micro)m in diameter and as thin as possible (approx 1-2 (micro)m), while having enough strength to be filled with DT as fast as possible to about 1000 atm. The authors have found that by optimizing the coating parameters in the glow discharge polymer (GDP) deposition system, traditionally used for making ICF targets, they can routinely make robust, ∼ 1.5 (micro)m thick, 900 (micro)m diameter GDP shells with buckle strengths of over 0.3 atm. This is twice the strength of shells made prior to the optimization and is comparable to values quoted for polyimide shells. In addition, these shells were found to be approximately three times more permeable and over 20% denser than previously made GDP shells. The combination of higher strength and permeability is ideal for direct drive cryogenic targets at OMEGA. Shells as thin as 0.5 (micro)m have been made. In this paper, the authors discuss the shell fabrication process, effects of modifying various GDP deposition parameters on shell properties and chemical composition

  9. Structural studies of thin films of semiconducting nanoparticles in polymer matrices

    International Nuclear Information System (INIS)

    Di Luccio, Tiziana; Piscopiello, Emanuela; Laera, Anna Maria; Antisari, Marco Vittori

    2007-01-01

    Ordered films of nanoscale materials are issue of wide interest for applications in several fields, such as optics, catalysis, and bioelectronics. In particular, semiconducting nanoparticles incorporation in a processable polymer film is an easy way to manipulate such materials for their application. We deposited thin layers of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles embedded in a thermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency and highly bio-compatible. The nanoparticles were obtained by thiolate precursors previously dispersed in the polymer upon thermal treatment at temperatures ranging between 200 and 300 deg. C depending on the desired size. The precursor/polymer solutions were spin-coated in order to get thin films. The spinning conditions were changed in order to optimise the layer thickness and uniformity. The samples were mainly characterised by X-ray reflectivity (XRR) and by high-resolution transmission electron microscopy (HRTEM) analyses. The thinnest layer we have deposited is 8 nm thick, as evaluated by XRR. The HRTEM measurements showed that the nanoparticles have quasi-spherical shape without evident microstructural defects. The size of the nanoparticles depends on the annealing temperature, e.g. at 232 deg. C the size of the CdS nanoparticles is about 4-5 nm

  10. Structural studies of thin films of semiconducting nanoparticles in polymer matrices

    Energy Technology Data Exchange (ETDEWEB)

    Di Luccio, Tiziana [ENEA, Centro Ricerche Brindisi, SS7 Appia Km 706, I-72100 Brindisi (Italy)], E-mail: tiziana.diluccio@portici.enea.it; Piscopiello, Emanuela; Laera, Anna Maria [ENEA, Centro Ricerche Brindisi, SS7 Appia Km 706, I-72100 Brindisi (Italy); Antisari, Marco Vittori [ENEA, Centro Ricerche Casaccia, Via Anguillarese 301, I-00060 S. Maria di Galeria (Roma) (Italy)

    2007-09-15

    Ordered films of nanoscale materials are issue of wide interest for applications in several fields, such as optics, catalysis, and bioelectronics. In particular, semiconducting nanoparticles incorporation in a processable polymer film is an easy way to manipulate such materials for their application. We deposited thin layers of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles embedded in a thermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency and highly bio-compatible. The nanoparticles were obtained by thiolate precursors previously dispersed in the polymer upon thermal treatment at temperatures ranging between 200 and 300 deg. C depending on the desired size. The precursor/polymer solutions were spin-coated in order to get thin films. The spinning conditions were changed in order to optimise the layer thickness and uniformity. The samples were mainly characterised by X-ray reflectivity (XRR) and by high-resolution transmission electron microscopy (HRTEM) analyses. The thinnest layer we have deposited is 8 nm thick, as evaluated by XRR. The HRTEM measurements showed that the nanoparticles have quasi-spherical shape without evident microstructural defects. The size of the nanoparticles depends on the annealing temperature, e.g. at 232 deg. C the size of the CdS nanoparticles is about 4-5 nm.

  11. Aquatic biofouling prevention by electrically charged nanocomposite polymer thin film membranes.

    Science.gov (United States)

    de Lannoy, Charles-François; Jassby, David; Gloe, Katie; Gordon, Alexander D; Wiesner, Mark R

    2013-03-19

    Electrically conductive polymer-nanocomposite (ECPNC) tight nanofiltration (NF) thin film membranes were demonstrated to have biofilm-preventing capabilities under extreme bacteria and organic material loadings. A simple route to the creation and application of these polyamide-carbon nanotube thin films is also reported. These thin films were characterized with SEM and TEM as well as FTIR to demonstrate that the carbon nanotubes are embedded within the polyamide and form ester bonds with trimesoyl chloride, one of the monomers of polyamide. These polymer nanocomposite thin film materials boast high electrical conductivity (∼400 S/m), good NaCl rejection (>95%), and high water permeability. To demonstrate these membranes' biofouling capabilities, we designed a cross-flow water filtration vessel with insulated electrical leads connecting the ECPNC membranes to an arbitrary waveform generator. In all experiments, conducted in highly bacterially contaminated LB media, flux tests were run until fluxes decreased by 45 ± 3% over initial flux. Biofilm-induced, nonreversible flux decline was observed in all control experiments and a cross-flow rinse with the feed solution failed to induce flux recovery. In contrast, flux decrease for the ECPNC membranes with an electric potential applied to their surface was only caused by deposition of bacteria rather than bacterial attachment, and flux was fully recoverable following a short rinse with the feed solution and no added cleaning agents. The prevention of biofilm formation on the ECPNC membranes was a long-term effect, did not decrease with use, and was highly reproducible.

  12. Impact of regioregularity on thin-film transistor and photovoltaic cell performances of pentacene-containing polymers

    KAUST Repository

    Jiang, Ying

    2012-01-01

    Regioregular pentacene-containing polymers were synthesized with alkylated bithiophene (BT) and cyclopentadithiophene (CPDT) as comonomers. Among them, 2,9-conjugated polymers PnBT-2,9 and PnCPDT-2,9 achieved the best performance in transistor and photovoltaic devices respectively. The former achieved the most highly ordered structures in thin films, yielding ambipolar transistor behavior with hole and electron mobilities up to 0.03 and 0.02 cm 2 V -1 s -1 on octadecylsilane-treated substrates. The latter achieved photovoltaic power conversion efficiencies up to 0.33%. The impact of regioregularity and direction of conjugation-extension (2,9 vs. 2,10), on thin-film order and device performance has been demonstrated for the pentacene-containing polymers for the first time, providing insight towards future functional material design. © 2012 The Royal Society of Chemistry.

  13. Vacuum-integrated electrospray deposition for highly reliable polymer thin film.

    Science.gov (United States)

    Park, Soohyung; Lee, Younjoo; Yi, Yeonjin

    2012-10-01

    Vacuum electrospray deposition (ESD) equipment was designed to prepare polymer thin films. The polymer solution can be injected directly into vacuum system through multi-stage pumping line, so that the solvent residues and ambient contaminants are highly reduced. To test the performance of ESD system, we fabricated organic photovoltaic cells (OPVCs) by injecting polymer solution directly onto the substrate inside a high vacuum chamber. The OPVC fabricated has the structure of Al∕P3HT:PCBM∕PEDOT:PSS∕ITO and was optimized by varying the speed of solution injection and concentration of the solution. The power conversion efficiency (PCE) of the optimized OPVC is 3.14% under AM 1.5G irradiation without any buffer layer at the cathode side. To test the advantages of the vacuum ESD, we exposed the device to atmosphere between the deposition steps of the active layer and cathode. This showed that the PCE of the vacuum processed device is 24% higher than that of the air exposed device and confirms the advantages of the vacuum prepared polymer film for high performance devices.

  14. Covalent bond force profile and cleavage in a single polymer chain

    Science.gov (United States)

    Garnier, Lionel; Gauthier-Manuel, Bernard; van der Vegte, Eric W.; Snijders, Jaap; Hadziioannou, Georges

    2000-08-01

    We present here the measurement of the single-polymer entropic elasticity and the single covalent bond force profile, probed with two types of atomic force microscopes (AFM) on a synthetic polymer molecule: polymethacrylic acid in water. The conventional AFM allowed us to distinguish two types of interactions present in this system when doing force spectroscopic measurements: the first interaction is associated with adsorption sites of the polymer chains onto a bare gold surface, the second interaction is directly correlated to the rupture process of a single covalent bond. All these bridging interactions allowed us to stretch the single polymer chain and to determine the various factors playing a role in the elasticity of these molecules. To obtain a closer insight into the bond rupture process, we moved to a force sensor stable in position when measuring attractive forces. By optimizing the polymer length so as to fulfill the elastic stability conditions, we were able for the first time to map out the entire force profile associated with the cleavage of a single covalent bond. Experimental data coupled with molecular quantum mechanical calculations strongly suggest that the breaking bond is located at one end of the polymer chain.

  15. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

    KAUST Repository

    Oba, Tatsuya

    2012-06-19

    We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate. (Figure presented) © 2012 American Chemical Society.

  16. Crystal structure and thin film morphology of BBL ladder polymer

    Energy Technology Data Exchange (ETDEWEB)

    Song, H H [Department of Macromolecular Science, Han Nam University, Taejon (Korea, Republic of); Fratini, A V [Department of Chemistry, University of Dayton, Dayton, OH (United States); Chabinyc, M [Department of Chemistry, University of Dayton, Dayton, OH (United States); Price, G E [University of Dayton Research, Dayton, OH (United States); Agrawal, A K [Systran Corporation, Dayton, OH (United States); Wang, C S [University of Dayton Research, Dayton, OH (United States); Burkette, J [University of Dayton Research, Dayton, OH (United States); Dudis, D S [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States); Arnold, F E [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States)

    1995-03-01

    Crystal structure and morphology of poly[7-oxo-7H-benz(d,e)imidazo(4`,5`:5,6)-benzimidazo(2,1-a)isoquinoline-3,4:10,11-tetrayl-10-carbonyl] (BBL) ladder-like polymer were studied. The polymer forms a two-dimensional lattice of nematic liquid crystalline structure. An orthorhombic unit cell with cell parameters of a=7.87 b=3.37 c=11.97A was determined from the fiber diffraction pattern. In thin films, the rigid chains spontaneously form a layered structure across the film thickness, but in a very unusual manner, i.e. the very large molecular plane is standing perpendicularly to the film surface plane. The results are identical to our recent results of poly(p-phenylene benzobisthiazole) (PBT) film [7]. The polymer, however, lost its anisotropic order upon extrusion into a film and resulted in a fiber-like structure. (orig.)

  17. Influence of film structure on the dewetting kinetics of thin polymer films in the solvent annealing process.

    Science.gov (United States)

    Zhang, Huanhuan; Xu, Lin; Lai, Yuqing; Shi, Tongfei

    2016-06-28

    On a non-wetting solid substrate, the solvent annealing process of a thin polymer film includes the swelling process and the dewetting process. Owing to difficulties in the in situ analysis of the two processes simultaneously, a quantitative study on the solvent annealing process of thin polymer films on the non-wetting solid substrate is extremely rare. In this paper, we design an experimental method by combining spectroscopic ellipsometry with optical microscopy to achieve the simultaneous in situ study. Using this method, we investigate the influence of the structure of swollen film on its dewetting kinetics during the solvent annealing process. The results show that for a thin PS film with low Mw (Mw = 4.1 kg mol(-1)), acetone molecules can form an ultrathin enriched layer between the PS film and the solid substrate during the swelling process. The presence of the acetone enriched layer accounts for the exponential kinetic behavior in the case of a thin PS film with low Mw. However, the acetone enriched layer is not observed in the case of a thin PS film with high Mw (Mw = 400 kg mol(-1)) and the slippage effect of polymer chains is valid during the dewetting process.

  18. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  19. Thin-film morphology of inkjet-printed single-droplet organic transistors using polarized Raman spectroscopy: effect of blending TIPS-pentacene with insulating polymer

    NARCIS (Netherlands)

    James, D.T.; Kjellander, B.K.C.; Smaal, W.T.T.; Gelinck, G.H.; Combe, C.; McCulloch, I.; Wilson, R.; Burroughes, J.H.; Bradley, D.D.C.; Kim, J.S.

    2011-01-01

    We report thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) using angle-dependent polarized Raman spectroscopy. We show this to be an effective technique to determine the degree of molecular order as well as to spatially resolve the orientation of

  20. Study of a thiophene-based polymer for optoelectronic applications

    International Nuclear Information System (INIS)

    Cheylan, S.; Fraleoni-Morgera, A.; Puigdollers, J.; Voz, C.; Setti, L.; Alcubilla, R.; Badenes, G.; Costa-Bizzarri, P.; Lanzi, M.

    2006-01-01

    A thiophene-based conjugated polymer bearing a cyano group (-CN) as a side chain substituent was successfully synthesized. The polymer evidences an excellent film ability from various organic solvents as well as an enhanced photoluminescence. The polymer has been characterized optically (Fourier Transformed Infrared spectroscopy, absorption and photoluminescence) in solution and in film, while X-ray diffraction measurements (XRD) of thin films were performed to investigate its bulk morphological features. From the absorption edge of the spectrum of a thin polymer film, the optical band gap of the polymer is estimated to be 2.0 eV, which corresponds to orange emission. Furthermore, a single layer light emitting diode (LED) was fabricated. The device produced bright stable electroluminescence at room temperature. All of the results indicate that this polymer is a promising emissive material for application in polymeric LEDs

  1. Implantable polymer/metal thin film structures for the localized treatment of cancer by Joule heating

    Science.gov (United States)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Theriault, Christian; Soboyejo, Wole

    2015-04-01

    This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The predictions are also compared to prior results from in vitro studies and relevant in vivo studies in the literature. The implications of the results are discussed for the potential application of polymer/metal thin film structures in hyperthermic treatment of cancer.

  2. Nanoparticles for dewetting suppression of thin polymer films used in chemical sensors

    International Nuclear Information System (INIS)

    Holmes, Melissa A.; Mackay, Michael E.; Giunta, Rachel K.

    2007-01-01

    Addition of fullerenes (C 60 or buckyballs) to a linear polymer has been found to eliminate dewetting when a thin (∼50 nm) film is exposed to solvent vapor. Based on neutron reflectivity measurements, it is found that the fullerenes form a coherent layer approximately 2 nm thick at the substrate - polymer film interface during the spin-coating process. The thickness and relative fullerene concentration (∼29 vol%) is not altered during solvent vapor annealing and it is thought this layer forms a solid-like buffer shielding the adverse van der Waals forces promoted by the underlying substrate. Several polymer films produced by spin- or spray-coating were tested on both silicon wafers and live surface acoustic wave sensors demonstrating fullerenes stabilize many different polymer types, prepared by different procedures and on various surfaces. Further, the fullerenes drastically improve sensor performance since dewetted films produce a sensor that is effectively inoperable

  3. Photoluminescence in conjugated polymers

    International Nuclear Information System (INIS)

    Furst, J.E.; Laugesen, R.; Dastoor, P.; McNeill, C.

    2002-01-01

    Full text: Conjugated polymers combine the electronic and optical properties of semiconductors with the processability of polymers. They contain a sequence of alternate single and double carbon bonds so that the overlap of unhybridised p z orbitals creates a delocalised ρ system which gives semiconducting properties with p-bonding (valence) and p* -antibonding (conduction) bands. Photoluminesence (PL) in conjugated polymers results from the radiative decay of singlet excitons confined to a single chain. The present work is the first in a series of studies in our laboratory that will characterize the optical properties of conjugated polymers. The experiment involves the illumination of thin films of conjugated polymer with UV light (I=360 nm) and observing the subsequent fluorescence using a custom-built, fluorescence spectrometer. Photoluminesence spectra provide basic information about the structure of the polymer film. A typical spectrum is shown in the accompanying figure. The position of the first peak is related to the polymer chain length and resolved multiple vibronic peaks are an indication of film structure and morphology. We will also present results related to the optical degradation of these materials when exposed to air and UV light

  4. Nanomechanics of biocompatible hollow thin-shell polymer microspheres.

    Science.gov (United States)

    Glynos, Emmanouil; Koutsos, Vasileios; McDicken, W Norman; Moran, Carmel M; Pye, Stephen D; Ross, James A; Sboros, Vassilis

    2009-07-07

    The nanomechanical properties of biocompatible thin-shell hollow polymer microspheres with approximately constant ratio of shell thickness to microsphere diameter were measured by nanocompression tests in aqueous conditions. These microspheres encapsulate an inert gas and are used as ultrasound contrast agents by releasing free microbubbles in the presence of an ultrasound field as a result of free gas leakage from the shell. The tests were performed using an atomic force microscope (AFM) employing the force-distance curve technique. An optical microscope, on which the AFM was mounted, was used to guide the positioning of tipless cantilevers on top of individual microspheres. We performed a systematic study using several cantilevers with spring constants varying from 0.08 to 2.3 N/m on a population of microspheres with diameters from about 2 to 6 microm. The use of several cantilevers with various spring constants allowed a systematic study of the mechanical properties of the microsphere thin shell at different regimes of force and deformation. Using thin-shell mechanics theory for small deformations, the Young's modulus of the thin wall material was estimated and was shown to exhibit a strong size effect: it increased as the shell became thinner. The Young's modulus of thicker microsphere shells converged to the expected value for the macroscopic bulk material. For high applied forces, the force-deformation profiles showed a reversible and/or irreversible nonlinear behavior including "steps" and "jumps" which were attributed to mechanical instabilities such as buckling events.

  5. Mechanical transduction via a single soft polymer

    Science.gov (United States)

    Hou, Ruizheng; Wang, Nan; Bao, Weizhu; Wang, Zhisong

    2018-04-01

    Molecular machines from biology and nanotechnology often depend on soft structures to perform mechanical functions, but the underlying mechanisms and advantages or disadvantages over rigid structures are not fully understood. We report here a rigorous study of mechanical transduction along a single soft polymer based on exact solutions to the realistic three-dimensional wormlike-chain model and augmented with analytical relations derived from simpler polymer models. The results reveal surprisingly that a soft polymer with vanishingly small persistence length below a single chemical bond still transduces biased displacement and mechanical work up to practically significant amounts. This "soft" approach possesses unique advantages over the conventional wisdom of rigidity-based transduction, and potentially leads to a unified mechanism for effective allosterylike transduction and relay of mechanical actions, information, control, and molecules from one position to another in molecular devices and motors. This study also identifies an entropy limit unique to the soft transduction, and thereby suggests a possibility of detecting higher efficiency for kinesin motor and mutants in future experiments.

  6. Fabrication of raised and inverted SU8 polymer waveguides

    Science.gov (United States)

    Holland, Anthony S.; Mitchell, Arnan; Balkunje, Vishal S.; Austin, Mike W.; Raghunathan, Mukund K.

    2005-01-01

    Polymer films with high optical transmission have been investigated for making optical devices for several years. SU8 photoresist and optical adhesives have been investigated for use as thin films for optical devices, not what they were originally designed for. Optical adhesives are typically a one component thermoset polymer and are convenient to use for making thin film optical devices such as waveguides. They are prepared in minutes as thin films unlike SU8, which has to be carefully thermally cured over several hours for optimum results. However SU8 can be accurately patterned to form the geometry of structures required for single mode optical waveguides. SU8 in combination with the lower refractive index optical adhesive films such as UV15 from Master Bond are used to form single and multi mode waveguides. SU8 is photopatternable but we have also used dry etching of the SU8 layer or the other polymer layers e.g. UV15 to form the ribs, ridges or trenches required to guide single modes of light. Optical waveguides were also fabricated using only optical adhesives of different refractive indices. The resolution obtainable is poorer than with SU8 and hence multi mode waveguides are obtained. Loss measurements have been obtained for waveguides of different geometries and material combinations. The process for making polymer waveguides is demonstrated for making large multi mode waveguides and microfluidic channels by scaling the process up in size.

  7. Polymer-coated compliant receivers for intact laser-induced forward transfer of thin films: experimental results and modelling

    Science.gov (United States)

    Feinaeugle, Matthias; Horak, Peter; Sones, Collin L.; Lippert, Thomas; Eason, Rob W.

    2014-09-01

    In this study, we investigate both experimentally and numerically laser-induced forward transfer (LIFT) of thin films to determine the role of a thin polymer layer coating the receiver with the aim of modifying the rate of deceleration and reduction of material stress preventing intact material transfer. A numerical model of the impact phase during LIFT shows that such a layer reduces the modelled stress. The evolution of stress within the transferred deposit and the substrate as a function of the thickness of the polymer layer, the transfer velocity and the elastic properties of the polymer are evaluated. The functionality of the polymer layer is verified experimentally by LIFT printing intact 1- m-thick bismuth telluride films and polymeric light-emitting diode pads onto a layer of 12-m-thick polydimethylsiloxane and 50-nm-thick poly(3,4-ethylenedioxythiophene) blended with poly(styrenesulfonate) (PEDOT:PSS), respectively. Furthermore, it is demonstrated experimentally that the introduction of such a compliant layer improves adhesion between the deposit and its substrate.

  8. Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

    International Nuclear Information System (INIS)

    Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.; Zhang, Fengjiao; Mohammadi, Erfan

    2017-01-01

    Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2-b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coating direction. The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.

  9. White Polymer Light-Emitting Diodes Based on Exciplex Electroluminescence from Polymer Blends and a Single Polymer.

    Science.gov (United States)

    Liang, Junfei; Zhao, Sen; Jiang, Xiao-Fang; Guo, Ting; Yip, Hin-Lap; Ying, Lei; Huang, Fei; Yang, Wei; Cao, Yong

    2016-03-09

    In this Article, we designed and synthesized a series of polyfluorene derivatives, which consist of the electron-rich 4,4'-(9-alkyl-carbazole-3,6-diyl)bis(N,N-diphenylaniline) (TPA-Cz) in the side chain and the electron-deficient dibenzothiophene-5,5-dioxide (SO) unit in the main chain. The resulting copolymer PF-T25 that did not comprise the SO unit exhibited blue light-emission with the Commission Internationale de L'Eclairage coordinates of (0.16, 0.10). However, by physically blending PF-T25 with a blue light-emitting SO-based oligomer, a novel low-energy emission correlated to exciplex emerged due to the appropriate energy level alignment of TPA-Cz and the SO-based oligomers, which showed extended exciton lifetime as confirmed by time-resolved photoluminescent spectroscopy. The low-energy emission was also identified in copolymers consisting of SO unit in the main chain, which can effectively compensate for the high-energy emission to produce binary white light-emission. Polymer light-emitting diodes based on the exciplex-type single greenish-white polymer exhibit the peak luminous efficiency of 2.34 cd A(-1) and the maximum brightness of 12 410 cd m(-2), with Commission Internationale de L'Eclairage color coordinates (0.27, 0.39). The device based on such polymer showed much better electroluminescent stability than those based on blending films. These observations indicated that developing a single polymer with the generated exciplex emission can be a novel and effective molecular design strategy toward highly stable and efficient white polymer light-emitting diodes.

  10. Brush-Coated Nanoparticle Polymer Thin Films: structure-mechanical-optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Green, Peter F. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering

    2014-08-15

    Our work was devoted to understanding the structure and properties of a class of thin film polymer nanocomposites (PNCs). PNCs are composed of polymer hosts into which nanoparticles (metallic nanoparticles, quantum dots, nanorods, C60, nanotubes) are incorporated. PNCs exhibit a diverse range of functional properties (optical, electronic, mechanical, biomedical, structural), determined in part by the chemical composition of the polymer host and the type of nanoparticle. The properties PNCs rely not only on specific functional, size-dependent, behavior of the nanoparticles, but also on the dispersion, and organizational order in some cases, inter-nanoparticle separation distances, and on relative interactions between the nanoparticles and the host. Therefore the scientific challenges associated with understanding the interrelations between the structure and function/properties of PNCs are far more complex than may be understood based only on the knowledge of the compositions of the constituents. The challenges of understanding the structure-function behavior of PNCs are further compounded by the fact that control of the dispersion of the nanoparticles within the polymer hosts is difficult; one must learn how to disperse inorganic particles within an organic host. The goal of this proposal was to develop an understanding of the connection between the structure and the thermal (glass transition), mechanical and optical properties of a specific class of PNCs. Specifically PNCs composed of polymer chain grafted gold nanoparticles within polymer hosts. A major objective was to understand how to develop basic principles that enable the fabrication of functional materials possessing optimized morphologies and combinations of materials properties.

  11. Flexible ITO-Free Polymer Solar Cells

    DEFF Research Database (Denmark)

    Angmo, Dechan; Krebs, Frederik C

    2013-01-01

    Indium tin oxide (ITO) is the material-of-choice for transparent conductors in any optoelectronic application. However, scarce resources of indium and high market demand of ITO have created large price fluctuations and future supply concerns. In polymer solar cells (PSCs), ITO is the single......-cost alternatives to ITO suitable for use in PSCs. These alternatives belong to four material groups: polymers; metal and polymer composites; metal nanowires and ultra-thin metal films; and carbon nanotubes and graphene. We further present the progress of employing these alternatives in PSCs and identify future...

  12. Effect of Polymer Binders on UV-Responsive Organic Thin-Film Phototransistors with Benzothienobenzothiophene Semiconductor.

    Science.gov (United States)

    Ljubic, Darko; Smithson, Chad S; Wu, Yiliang; Zhu, Shiping

    2016-02-17

    The influence of polymer binders on the UV response of organic thin-film phototransistors (OTF-PTs) is reported. The active channel of the OTF-PTs was fabricated by blending a UV responsive 2,7-dipenty-[1]benzothieno[2,3-b][1]benzothiophene (C5-BTBT) as small molecule semiconductor and a branched unsaturated polyester (B-upe) as dielectric binder (ratio 1:1). To understand the influence of the polymer composition on the photoelectrical properties and UV response of C5-BTBT, control blends were prepared using common dielectric polymers, namely, poly(vinyl acetate) (PVAc), polycarbonate (PC), and polystyrene (PS), for comparison. Thin-film morphology and nanostructure of the C5-BTBT/polymer blends were investigated by means of optical and atomic force microscopy, and powder X-ray diffraction, respectively. Electrical and photoelectrical characteristics of the studied OTF-PTs were evaluated in the dark and under UV illumination with a constant light intensity (P = 3 mW cm(-2), λ = 365 nm), respectively, using two- and three-terminal I-V measurements. Results revealed that the purposely chosen B-upe polymer binder strongly affected the UV response of OTF-PTs. A photocurrent increase of more than 5 orders of magnitude in the subthreshold region was observed with a responsivity as high as 9.7 AW(-1), at VG = 0 V. The photocurrent increase and dramatic shift of VTh,average (∼86 V) were justified by the high number of photogenerated charge carriers upon the high trap density in bulk 8.0 × 10(12) cm(-2) eV(-1) generated by highly dispersed C5-BTBT in B-upe binder. Compared with other devices, the B-upe OTF-PTs had the fastest UV response times (τr1/τr2 = 0.5/6.0) reaching the highest saturated photocurrent (>10(6)), at VG = -5 V and VSD = -60 V. The enhanced UV sensing properties of B-upe based OTF-PTs were attributed to a self-induced thin-film morphology. The enlarged interface facilitated the electron withdrawing/donating functional groups in the polymer chains in

  13. Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films

    Science.gov (United States)

    Jira, Nicholas C.; Sabirianov, Ildar; Ilie, Carolina C.

    We discuss herein the nanocomposite organic thin film diodes for the use of plasmonic solar cells. This experimental work follows the theoretical calculations done for plasmonic solar cells using the MNPBEM toolbox for MatLab. These calculations include dispersion curves and amount of light scattering cross sections for different metallic nanoparticles. This study gives us clear ideas on what to expect from different metals, allowing us to make the best choice on what to use to obtain the best results. One specific technique for light trapping in thin films solar cells utilizes metal nanoparticles on the surface of the semiconductor. The characteristics of the metal, semiconductor interface allows for light to be guided in between them causing it to be scattered, allowing for more chances of absorption. The samples were fabricated using organic thin films made from polymers and metallic nanoparticles, more specifically Poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer and silver or gold nanoparticles. The two fabrication methods applied include spin coating and Langmuir-Blodgett technique. The transport properties are obtained by analyzing the I-V curves. We will also discuss the resistance, resistivity, conductance, density of charge carriers. SUNY Oswego SCAC Grant.

  14. Film-thickness dependence of structure formation in ultra-thin polymer blend films

    CERN Document Server

    Gutmann, J S; Stamm, M

    2002-01-01

    We investigated the film-thickness dependence of structure formation in ultra-thin polymer blend films prepared from solution. As a model system we used binary blends of statistical poly(styrene-co-p-bromostyrene) copolymers of different degrees of bromination. Ultra-thin-film samples differing in miscibility and film thickness were prepared via spin coating of common toluene solutions onto silicon (100) substrates. The resulting morphologies were investigated with scanning force microscopy, reflectometry and grazing-incidence scattering techniques using both X-rays and neutrons in order to obtain a picture of the sample structure at and below the sample surface. (orig.)

  15. Polymer functionalized single-walled carbon nanotube composites and semi-fluorinated quaternary ammonium polymer colloids and coatings

    Science.gov (United States)

    Paul, Abhijit

    Scope and Method of Study: Current study focused on understanding of "wetting" and "dewetting" phenomena between surfaces of single-walled carbon nanotubes (SWCNT) which are lightly grafted with polymer chains by reversible-deactivation radical polymerization, when they are mixed with matrix chains of the same architecture as grafts. Effects of grafts to matrix chain lengths on SWCNT dispersion in matrix polymers were studied by measuring electrical conductivity, glass transition temperature, and storage and loss moduli of nanocomposites. Another area of work was to design semi-fluorinated copolymers with core-shell morphology by emulsion polymerization, study their catalytic activities for hydrolyses of Paraoxon, a toxic insecticide, in the forms of both colloidal dispersions and films, and to characterize the surfaces of the films by atomic force microscopy and by dynamic contact angle measurements. Findings and Conclusions: The glass transition temperature ( Tg) of polystyrene (PS) filled with SWCNT grafted with PS of different lengths increased from 99 to 109 °C at 6 wt% of SWCNT followed by a plateau. The heat capacity (DeltaCp ) at Tg continued to decrease only for the smallest chain length grafted PS nanocomposites. SWCNT/PS nanocomposites had low electrical conductivity and showed no percolation threshold due to the thick polymer coatings. A key finding was that the SWCNT surface can accommodate only a fixed numbers of styrene units. Similar results on change in Tg were obtained for SWCNT/PMMA nanocomposites when molecular weight of matrix (Mmatrix) ≥ molecular weight of grafts (Mgraft). No change in DeltaCp was observed for SWCNT/PMMA nanocomposites. "Wetting" to "dewetting" occurred Mmatrix/ Mgraft ≈ 1. For Mmatrix > Mgraft, electrical conductivity of nanocomposites reached the value of 10-9 S cm-1 at 1.0 wt% nanotube loading and had percolation threshold of electrical conductivity at ˜0.25 wt% SWCNT. Raman and UV-vis-NIR data confirmed that

  16. RESEARCH ON THE ELECTRONIC AND OPTICAL PROPERTIES OF POLYMER AND OTHER ORGANIC MOLECULAR THIN FILMS

    Energy Technology Data Exchange (ETDEWEB)

    ALEXEI G. VITUKHNOVSKY; IGOR I. SOBELMAN - RUSSIAN ACADEMY OF SCIENCES

    1995-09-06

    Optical properties of highly ordered films of poly(p-phenylene) (PPP) on different substrates, thin films of mixtures of conjugated polymers, of fullerene and its composition with polymers, molecular J-aggregates of cyanine dyes in frozen matrices have been studied within the framework of the Agreement. Procedures of preparation of high-quality vacuum deposited PPP films on different substrates (ITO, Si, GaAs and etc.) were developed. Using time-correlated single photon counting technique and fluorescence spectroscopy the high quality of PPP films has been confirmed. Dependence of structure and optical properties on the conditions of preparation were investigated. The fluorescence lifetime and spectra of highly oriented vacuum deposited PPP films were studied as a function of the degree of polymerization. It was shown for the first time that the maximum fluorescence quantum yield is achieved for the chain length approximately equal to 35 monomer units. The selective excitation of luminescence of thin films of PPP was performed in the temperature range from 5 to 300 K. The total intensity of luminescence monotonically decreases with decreasing temperature. Conditions of preparation of highly cristallyne fullerene C{sub 60} films by the method of vacuum deposition were found. Composites of C{sub 60} with conjugated polymers PPV and polyacetylene (PA) were prepared. The results on fluorescence quenching, IR and resonant Raman spectroscopy are consistent with earlier reported ultrafast photoinduced electron transfer from PPV to C{sub 60} and show that the electron transfer is absent in the case of the PA-C{sub 60} composition. Strong quenching of PPV fluorescence was observed in the PPV-PA blends. The electron transfer from PPV to PA can be considered as one of the possible mechanisms of this quenching. The dynamics of photoexcitations in different types of J-aggregates of the carbocyanine dye was studied at different temperatures in frozen matrices. The optical

  17. Non-equilibrium dynamics of single polymer adsorption to solid surfaces

    International Nuclear Information System (INIS)

    Panja, Debabrata; Barkema, Gerard T; Kolomeisky, Anatoly B

    2009-01-01

    The adsorption of polymers to surfaces is crucial for understanding many fundamental processes in nature. Recent experimental studies indicate that the adsorption dynamics is dominated by non-equilibrium effects. We investigate the adsorption of a single polymer of length N to a planar solid surface in the absence of hydrodynamic interactions. We find that for weak adsorption energies the adsorption timescales ∼N (1+2ν)/(1+ν) , where ν is the Flory exponent for the polymer. We argue that in this regime the single chain adsorption is closely related to a field-driven polymer translocation through narrow pores. Surprisingly, for high adsorption energies the adsorption time becomes longer, as it scales as ∼N 1+ν , which is explained by strong stretching of the unadsorbed part of the polymer close to the adsorbing surface. These two dynamic regimes are separated by an energy scale that is characterized by non-equilibrium contributions during the adsorption process. (fast track communication)

  18. Modified voltammetric, impedimetric and optical behavior of polymer- assisted sol-gel MgFe2O4 nanostructured thin films

    International Nuclear Information System (INIS)

    Bazhan, Z.; Ghodsi, F.E.; Mazloom, J.

    2017-01-01

    Highlights: •Electrochemical properties of spinel PEG/PVP MgFe 2 O 4 thin films prepared by spin coating technique have been investigated. •PSD analysis indicated that spectral roughness of films decreased by polymer incorporation. •Optical calculations exhibited a blue shift on optical band gap by polymer addition. •CV curves revealed that ion storage capacitance of PEG/MgFe 2 O 4 is two times higher than MgFe 2 O 4 thin films. •EIS analysis confirmed that incorporation of appropriate amount of PEG reduced the charge transfer resistance. -- Abstract: The effect of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on physical properties of sol-gel prepared magnesium ferrite (MF) thin films was investigated. The X-ray diffraction (XRD) results showed the formation of cubic spinel magnesium ferrite for all samples. The surface morphology of films changed and average surface roughness decreased by polymer addition. The height-height correlation function and fractal dimension were evaluated using cube counting and triangulation methods from atomic force microscopy (AFM) images. The refractive index and extinction coefficient of MF thin films decreased by adding polymer while the band gap value increased from 2.24 to 2.72 eV. The PEG addition enhanced the electrochemical performance while PVP addition didn’t have significant effect on cyclic voltammetry (CV) of magnesium ferrite thin films. The sample with highest value of PEG showed the maximum specific capacitance (68.5 mF cm −2 ) and the smallest charge transfer resistance (565 Ω) among all samples.

  19. Non-classical light emission from single conjugated polymers

    Science.gov (United States)

    Hollars, Christopher; Lane, Stephen; Huser, Thomas

    2002-03-01

    Photon-antibunching from single, isolated molecules of collapsed-chain poly[2-methoxy,5-(2’-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been observed using confocal microscopy techniques. Efficient inter-segment energy transfer in collapsed-chain conjugated polymers leads to emission from an average of only 2-3 active sites on a polymer chain that is composed of hundreds of quasi-chromophores. These few centers consist of the segments with the lowest excitation energy and are supplied by the efficient light-harvesting and energy transfer of the surrounding higher-energy segments. This effect depends on the conformation of the polymer molecules, which is controlled by solvent polarity. These results provide new insight into the controversial photophysics of conjugated polymers and their application in optoelectronic devices.

  20. Thickness dependent structural ordering, degradation and metastability in polysilane thin films: A photoluminescence study on representative σ-conjugated polymers

    International Nuclear Information System (INIS)

    Urbánek, Pavel; Kuřitka, Ivo

    2015-01-01

    We present a fundamental experimental study based on the fluorescence investigation of thin σ-conjugated polymer films, where the dependence of optoelectrical properties and UV degradation on film thickness ranging from nano- to microscale was studied. Such extensive and detailed study was performed for the first time and observed spectral shifts in emission and excitation spectra and UV degradation retardation point towards the conclusions that there exists a threshold thickness where the material degradation behavior, electron delocalization and structure suddenly change. The development of well aligned polymeric chain structure between the nano- and micrometer thickness (on the mesoscale) was shown responsible for the manifested phenomena. The material thicker than critical 500 nm has extremely small Stokes' shift, maximum extended σ-delocalization along the silicon polymer backbone and exhibits remarkable UV degradation slowdown and self-recovery ability. On the contrary, the electronic properties of thin films below 80 nm resemble those of random coils in solutions. The films of moderate thickness show relatively steep transition between these two modes of structural ordering and resulting properties. Altogether, we consider this complex phenomenon as a consequence of the mesoscale effect, which is an only recently introduced concept in polymer thin films. - Highlights: • Photoluminescence was used as a tool for structural investigation of polysilanes. • Primary study of strong dependence of thin polymer film structure on mesoscale. • A mesoscale effect observed for the first time on sigma conjugated polymers. • Conjugation length is dramatically extended in thicker films than in nanoscale. • Self-recovery effect was shown to be dependent on the mesoscale as well.

  1. Well-defined single-chain polymer nanoparticles via thiol-Michael addition

    NARCIS (Netherlands)

    Kröger, A. Pia P.; Boonen, Roy J.E.A.; Paulusse, Jos M.J.

    2017-01-01

    A synthetic strategy has been developed giving facile access to well-defined single-chain polymer nanoparticles (SCNPs) from styrene-, acrylate- and methacrylate-based polymers. Random copolymers (polydispersity indices 1.10–1.15) of methyl (meth)acrylate, benzyl methacrylate or styrene containing

  2. Capillary bending of a thin polymer film floating on a liquid bath

    Science.gov (United States)

    Twohig, Timothy; Croll, Andrew B.

    Thin elastic films and shells are very important in schemes for the encapsulation and protection of fluids from their environment. Capillary origami is a particularly poignant example of how useful fluid/film structures can be formed. The interactions of fluids on thin-films which themselves lie on another surface (fluid or low friction solid) need to be studied if the differences from fluid-fluid and fluid-solid film interfaces are to be fully appreciated. In this experiment, we examine the triple line that occurs when a fluid is resting on a thin polymer film which is itself floating on a second fluid. The top fluid has a high-energy air/fluid interface which can be minimized by deforming the film in a manner that reduces the total air/fluid interface. We create a one-dimensional experiment in order to isolate the basic physics that occurs as the tension of the top fluid pulls on the thin film. Notably, the 1D geometry removes all the complexity incurred by thin films in biaxial stress states (such as wrinkling, folding and crumpling) from the problem. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

  3. Comparison study of ITO thin films deposited by sputtering at room temperature onto polymer and glass substrates

    International Nuclear Information System (INIS)

    Guillen, C.; Herrero, J.

    2005-01-01

    Indium tin oxide (ITO) thin films have been grown simultaneously onto glass and polymer substrates at room temperature by sputtering from ceramic target. The structure, morphology and electro-optical characteristics of the ITO/glass and ITO/polymer samples have been analyzed by X-ray diffraction, atomic force microscopy, four-point electrical measurements and spectrophotometry. In the selected experimental conditions, the polycrystalline ITO coating shows higher average grain size and higher conductivity, with similar visible transmittance, onto the polymer than onto the glass substrate

  4. Non-equilibrium dynamics of single polymer adsorption to solid surfaces

    NARCIS (Netherlands)

    Panja, D.; Barkema, G.T.; Kolomeisky, A.B.

    2009-01-01

    The adsorption of polymers to surfaces is crucial for understanding many fundamental processes in nature. Recent experimental studies indicate that the adsorption dynamics is dominated by non-equilibrium effects. We investigate the adsorption of a single polymer of length N to a planar solid surface

  5. Thin and flexible all-solid supercapacitor prepared from novel single wall carbon nanotubes/polyaniline thin films obtained in liquid-liquid interfaces

    Science.gov (United States)

    de Souza, Victor Hugo Rodrigues; Oliveira, Marcela Mohallem; Zarbin, Aldo José Gorgatti

    2014-08-01

    The present work describes for the first time the synthesis and characterization of single wall carbon nanotubes/polyaniline (SWNTs/PAni) nanocomposite thin films in a liquid-liquid interface, as well as the subsequent construction of a flexible all-solid supercapacitor. Different SWNTs/PAni nanocomposites were prepared by varying the ratio of SWNT to aniline, and the samples were characterized by scanning and transmission electron microscopy, Raman and UV-Vis spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The pseudo-capacitive behavior of the nanocomposites was evaluated by charge/discharge galvanostatic measurements. The presence of the SWNTs affected the electronic and vibrational properties of the polyaniline and also improved the pseudo-capacitive behavior of the conducting polymer. A very thin and flexible all-solid device was manufactured using two electrodes (polyethylene terephthalate-PET covered with the SWNT/PAni nanocomposite separated by a H2SO4-PVA gel electrolyte). The pseudo-capacitive behavior was characterized by a volumetric specific capacitance of approximately 76.7 F cm-3, even under mechanical deformation, indicating that this nanocomposite has considerable potential for application in new-generation energy storage devices.

  6. Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal-Organic Framework Thin Film

    KAUST Repository

    Lu, Chunjing; Ben, Teng; Xu, Shixian; Qiu, Shilun

    2014-01-01

    A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous

  7. Self-healing in single and multiple fiber(s reinforced polymer composites

    Directory of Open Access Journals (Sweden)

    Woldesenbet E.

    2010-06-01

    Full Text Available You Polymer composites have been attractive medium to introduce the autonomic healing concept into modern day engineering materials. To date, there has been significant research in self-healing polymeric materials including several studies specifically in fiber reinforced polymers. Even though several methods have been suggested in autonomic healing materials, the concept of repair by bleeding of enclosed functional agents has garnered wide attention by the scientific community. A self-healing fiber reinforced polymer composite has been developed. Tensile tests are carried out on specimens that are fabricated by using the following components: hollow and solid glass fibers, healing agent, catalysts, multi-walled carbon nanotubes, and a polymer resin matrix. The test results have demonstrated that single fiber polymer composites and multiple fiber reinforced polymer matrix composites with healing agents and catalysts have provided 90.7% and 76.55% restoration of the original tensile strength, respectively. Incorporation of functionalized multi-walled carbon nanotubes in the healing medium of the single fiber polymer composite has provided additional efficiency. Healing is found to be localized, allowing multiple healing in the presence of several cracks.

  8. Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

    Science.gov (United States)

    Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

    2015-02-11

    New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

  9. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K. [Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Yoon, J. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Guha, S. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)], E-mail: guhas@missouri.edu

    2008-08-30

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the {beta} phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  10. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    International Nuclear Information System (INIS)

    Gupta, R.K.; Ghosh, K.; Kahol, P.K.; Yoon, J.; Guha, S.

    2008-01-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films

  11. Pulsed laser thin film growth of di-octyl substituted polyfluorene and its co-polymers

    Science.gov (United States)

    Gupta, R. K.; Ghosh, K.; Kahol, P. K.; Yoon, J.; Guha, S.

    2008-08-01

    Matrix-assisted pulsed laser deposition (PLD) allows a controlled layer-by-layer growth of polymer films. Di-octyl substituted polyfluorene (PF8) and its copolymers were deposited as thin films using matrix-assisted PLD by employing a KrF excimer laser with a fluence of 125 mJ/pulses. The optical and structural properties of these films are compared with spincoated films via Raman spectroscopy, absorption and photoluminescence. The Raman spectra of both PLD and spincoated films are similar indicating that the polymer films deposited via PLD maintain their molecular structure. Both the spincoated and the PLD grown PF8 films that were cast from toluene show the presence of the β phase. Benzothiadiazole substituted PF8 (F8BT) and butyl phenyl-substituted PF8 (PFB) PLD grown films show a slightly broader emission compared to the spincoated films, which is attributed to an enhanced intermolecular interaction in the PLD grown thin films.

  12. High-pressure oxygenation of thin-wall YBCO single-domain samples

    International Nuclear Information System (INIS)

    Chaud, X; Savchuk, Y; Sergienko, N; Prikhna, T; Diko, P

    2008-01-01

    The oxygen annealing of ReBCO bulk material, necessary to achieve superconducting properties, usually induces micro- and macro-cracks. This leads to a crack-assisted oxygenation process that allows oxygenating large bulk samples faster than single crystals. But excellent superconducting properties are cancelled by the poor mechanical ones. More progressive oxygenation strategy has been shown to reduce drastically the oxygenation cracks. The problem then arises to keep a reasonable annealing time. The concept of bulk Y123 single-domain samples with thin-wall geometry has been introduced to bypass the inherent limitation due to a slow oxygen diffusion rate. But it is not enough. The use of a high oxygen pressure (16 MPa) enables to speed up further the process. It introduces a displacement in the equilibrium phase diagram towards higher temperatures, i.e., higher diffusion rates, to achieve a given oxygen content in the material. Remarkable results were obtained by applying such a high pressure oxygen annealing process on thin-wall single-domain samples. The trapped field of 16 mm diameter Y123 thin-wall single-domain samples was doubled (0.6T vs 0.3T at 77K) using an annealing time twice shorter (about 3 days). The initial development was made on thin bars. The advantage of thin-wall geometry is that such an annealing can be applied directly to a much larger sample

  13. Unconventional phase transitions in a constrained single polymer chain

    International Nuclear Information System (INIS)

    Klushin, L I; Skvortsov, A M

    2011-01-01

    Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)

  14. Diketopyrrolopyrrole-Based Conjugated Polymer Entailing Triethylene Glycols as Side Chains with High Thin-Film Charge Mobility without Post-Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Si-Fen [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; University of Chinese Academy of Sciences, Beijing 100049 P. R. China; Liu, Zi-Tong [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Cai, Zheng-Xu [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Dyson, Matthew J. [Department of Materials and Centre for Plastic Electronics, Imperial College London, London SW72AZ UK; Stingelin, Natalie [Department of Materials and Centre for Plastic Electronics, Imperial College London, London SW72AZ UK; Chen, Wei [Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue Lemont IL 60439 USA; Institute for Molecular Engineering, The University of Chicago, 5640 South Ellis Avenue Chicago IL 60637 USA; Ju, Hua-Jun [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Zhang, Guan-Xin [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Zhang, De-Qing [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; University of Chinese Academy of Sciences, Beijing 100049 P. R. China

    2017-04-18

    Side chain engineering of conjugated donor-acceptor polymers is a new way to manipulate their optoelectronic properties. Two new diketopyrrolopyrrole (DPP)-terthiophene-based conjugated polymers PDPP3T-1 and PDPP3T-2, with both hydrophilic triethylene glycol (TEG) and hydrophobic alkyl chains, are reported. It is demonstrated that the incorporation of TEG chains has a significant effect on the interchain packing and thin-film morphology with noticeable effect on charge transport. Polymer chains of PDPP3T-1 in which TEG chains are uniformly distributed can self-assemble spontaneously into a more ordered thin film. As a result, the thin film of PDPP3T-1 exhibits high saturated hole mobility up to 2.6 cm(2) V-1 s(-1) without any post-treatment. This is superior to those of PDPP3T with just alkyl chains and PDPP3T-2. Moreover, the respective field effect transistors made of PDPP3T-1 can be utilized for sensing ethanol vapor with high sensitivity (down to 100 ppb) and good selectivity.

  15. Crack density and electrical resistance in indium-tin-oxide/polymer thin films under cyclic loading

    KAUST Repository

    Mora Cordova, Angel; Khan, Kamran; El Sayed, Tamer

    2014-01-01

    Here, we propose a damage model that describes the degradation of the material properties of indium-tin-oxide (ITO) thin films deposited on polymer substrates under cyclic loading. We base this model on our earlier tensile test model and show

  16. Molecular Orientation of Conjugated Polymer Chains in Nanostructures and Thin Films: Review of Processes and Application to Optoelectronics

    Directory of Open Access Journals (Sweden)

    Varun Vohra

    2017-01-01

    Full Text Available Semiconducting polymers are composed of elongated conjugated polymer backbones and side chains with high solubility and mechanical properties. The combination of these two features results in a high processability and a potential to orient the conjugated backbones in thin films and nanofibers. The thin films and nanofibers are usually composed of highly crystalline (high charge transport and amorphous parts. Orientation of conjugated polymer can result in enhanced charge transport or optical properties as it induces increased crystallinity or preferential orientation of the crystallites. After summarizing the potential strategies to exploit molecular order in conjugated polymer based optoelectronic devices, we will review some of the fabrication processes to induce molecular orientation. In particular, we will review the cases involving molecular and interfacial interactions, unidirectional deposition processes, electrospinning, and postdeposition mechanical treatments. The studies presented here clearly demonstrate that process-controlled molecular orientation of the conjugated polymer chains can result in high device performances (mobilities over 40 cm2·V−1·s−1 and solar cells with efficiencies over 10%. Furthermore, the peculiar interactions between molecularly oriented polymers and polarized light have the potential not only to generate low-cost and low energy consumption polarized light sources but also to fabricate innovative devices such as solar cell integrated LCDs or bipolarized LEDs.

  17. Synthesis of Thin Film Composite Metal-Organic Frameworks Membranes on Polymer Supports

    KAUST Repository

    Barankova, Eva

    2017-06-01

    Since the discovery of size-selective metal-organic frameworks (MOF) researchers have tried to manufacture them into gas separation membranes. ZIF-8 became the most studied MOF for membrane applications mainly because of its simple synthesis, good chemical and thermal stability, recent commercial availability and attractive pore size. The aim of this work is to develop convenient methods for growing ZIF thin layers on polymer supports to obtain defect-free ZIF membranes with good gas separation properties. We present new approaches for ZIF membranes preparation on polymers. We introduce zinc oxide nanoparticles in the support as a secondary metal source for ZIF-8 growth. Initially the ZnO particles were incorporated into the polymer matrix and later on the surface of the polymer by magnetron sputtering. In both cases, the ZnO facilitated to create more nucleation opportunities and improved the ZIF-8 growth compared to the synthesis without using ZnO. By employing the secondary seeded growth method, we were able to obtain thin (900 nm) ZIF-8 layer with good gas separation performance. Next, we propose a metal-chelating polymer as a suitable support for growing ZIF layers. Defect-free ZIF-8 films with a thickness of 600 nm could be obtained by a contra-diffusion method. ZIF-8 membranes were tested for permeation of hydrogen and hydrocarbons, and one of the highest selectivities reported so far for hydrogen/propane, and propylene/propane was obtained. Another promising method to facilitate the growth of MOFs on polymeric supports is the chemical functionalization of the support surface with functional groups, which can complex metal ions and which can covalently bond the MOF crystals. We functionalized the surface of a common porous polymeric membrane with amine groups, which took part in the reaction to form ZIF-8 nanocrystals. We observed an enhancement in adhesion between the ZIF layer and the support. The effect of parameters of the contra-diffusion experiment

  18. Single-mode solid-state polymer dye laser fabricated with standard I-line UV lithography

    DEFF Research Database (Denmark)

    Balslev, Søren; Mironov, Andrej; Nilsson, Daniel

    2005-01-01

    We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G.......We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G....

  19. Single-polymer dynamics under constraints: scaling theory and computer experiment

    International Nuclear Information System (INIS)

    Milchev, Andrey

    2011-01-01

    The relaxation, diffusion and translocation dynamics of single linear polymer chains in confinement is briefly reviewed with emphasis on the comparison between theoretical scaling predictions and observations from experiment or, most frequently, from computer simulations. Besides cylindrical, spherical and slit-like constraints, related problems such as the chain dynamics in a random medium and the translocation dynamics through a nanopore are also considered. Another particular kind of confinement is imposed by polymer adsorption on attractive surfaces or selective interfaces-a short overview of single-chain dynamics is also contained in this survey. While both theory and numerical experiments consider predominantly coarse-grained models of self-avoiding linear chain molecules with typically Rouse dynamics, we also note some recent studies which examine the impact of hydrodynamic interactions on polymer dynamics in confinement. In all of the aforementioned cases we focus mainly on the consequences of imposed geometric restrictions on single-chain dynamics and try to check our degree of understanding by assessing the agreement between theoretical predictions and observations. (topical review)

  20. Dynamical behavior of a single polymer chain under nanometric confinement

    Science.gov (United States)

    Lagrené, K.; Zanotti, J.-M.; Daoud, M.; Farago, B.; Judeinstein, P.

    2010-10-01

    We address the dynamical behavior of a single polymer chain under nanometric confinement. We consider a polymer melt made of a mixture of hydrogenated and deuterated high molecular mass Poly(Ethylene Oxide) (PEO). The confining material is a membrane of Anodic Aluminum Oxide (AAO), a macroscopically highly ordered confining system made of parallel cylindrical channels. We use Neutron Spin-Echo (NSE) under the Zero Average Contrast (ZAC) condition to, all at once, i) match the intense porous AAO detrimental elastic SANS (Small Angle Neutron Scattering) contribution to the total intermediate scattering function I(Q,t) and ii) measure the Q dependence of the dynamical modes of a single chain under confinement. The polymer dynamics is probed on an extremely broad spacial ([2.2 10-2 Å-1, 0.2 Å-1]) and temporal ([0.1 ns, 600 ns]) ranges. We do not detect any influence of confinement on the polymer dynamics. This result is discussed in the framework of the debate on the existence of a "corset effect" recently suggested by NMR relaxometry data.

  1. Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

    KAUST Repository

    Han, Yang

    2018-03-13

    Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

  2. Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

    KAUST Repository

    Han, Yang; Fei, Zhuping; Lin, Yen-Hung; Martin, Jaime; Tuna, Floriana; Anthopoulos, Thomas D.; Heeney, Martin

    2018-01-01

    Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

  3. Use of two-phase aqueous systems based on water-soluble polymers in thin-layer and extraction chromatography for recovery and separtion of actinides

    International Nuclear Information System (INIS)

    Molochnikova, N.P.; Shkinev, V.M.; Myasoedov, B.F.

    1995-01-01

    The feasibility has been demonstrated of using two-phase aqueous systems based on water-soluble polymers, polyethylene glycol and dextran sulfate, in thin-layer and extraction chromatography for recovery and separation of actinides. A convenient method has been proposed for continuous recovery of 239 Np from 243 Am, originating from differences in sorption of tri- and pentavalent actinides from sulfate solutions containing potassium phosphotungstate by silica gel impregnated with polyethylene glycol. New plates for thin-layer chromatography using water-soluble polymers have been developed. These plates were used to study behavior of americium in various oxidation states in thin sorbent layers

  4. Self organized striping in ultra thin polymer films near melt: An investigation using Monte Carlo simulation

    Science.gov (United States)

    Singh, Satya Pal

    2018-05-01

    This paper work presents the results of Monte Carlo simulation performed for ultra thin short chained polymer films near melt, under strong confinement. Thin polymer films get ruptured when annealed above their glass transition temperatures. The pattern formations are generally explained on the basis of spinodal mechanism, if the thickness of the film is of the order of few tens of nanometers i.e. film seems to tear apart in strips. The free end segments of the chains are more dynamic and coalescence into one another. This process seems to dominate over the spinodal waves resulting into a different type of dynamics. Polymer chains with 30 monomers are taken. 160, 200 and 240 chains are taken for three different cases of the studies. The three cases correspond to three different thickness of the films with 8, 10 and 12 layers of chains along direction perpendicular to the confining substrates. The bottom surface has affinity to monomers, whereas the upper surface has hard wall interaction with the monomers. Different time micrographs of the films are plotted along with density distributions of the monomers to explore the process.

  5. Single-Chain Folding of Synthetic Polymers: A Critical Update.

    Science.gov (United States)

    Altintas, Ozcan; Barner-Kowollik, Christopher

    2015-11-23

    The current contribution serves as a critical update to a previous feature article from us (Macromol. Rapid Commun. 2012, 33, 958-971), and highlights the latest advances in the preparation of single chain polymeric nanoparticles and initial-yet promising-attempts towards mimicking the structure of natural biomacromolecules via single-chain folding of well-defined linear polymers via so-called single chain selective point folding and repeat unit folding. The contribution covers selected examples from the literature published up to ca. September 2015. Our aim is not to provide an exhaustive review but rather highlight a selection of new and exciting examples for single-chain folding based on advanced macromolecular precision chemistry. Initially, the discussion focuses on the synthesis and characterization of single-chain folded structures via selective point folding. The second part of the feature article addresses the folding of well-defined single-chain polymers by means of repeat unit folding. The current state of the art in the field of single-chain folding indicates that repeat unit folding-driven nanoparticle preparation is well-advanced, while initial encouraging steps towards building selective point folding systems have been taken. In addition, a summary of the-in our view-open key questions is provided that may guide future biomimetic design efforts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Preparation, Single-Molecule Manipulation, and Energy Transfer Investigation of a Polyfluorene-graft-DNA polymer.

    Science.gov (United States)

    Madsen, Mikael; Christensen, Rasmus S; Krissanaprasit, Abhichart; Bakke, Mette R; Riber, Camilla F; Nielsen, Karina S; Zelikin, Alexander N; Gothelf, Kurt V

    2017-08-04

    Conjugated polymers have been intensively studied due to their unique optical and electronic properties combined with their physical flexibility and scalable bottom up synthesis. Although the bulk qualities of conjugated polymers have been extensively utilized in research and industry, the ability to handle and manipulate conjugated polymers at the nanoscale lacks significantly behind. Here, the toolbox for controlled manipulation of conjugated polymers was expanded through the synthesis of a polyfluorene-DNA graft-type polymer (poly(F-DNA)). The polymer possesses the characteristics associated with the conjugated polyfluorene backbone, but the protruding single-stranded DNA provides the material with an exceptional addressability. This study demonstrates controlled single-molecule patterning of poly(F-DNA), as well as energy transfer between two different polymer-DNA conjugates. Finally, highly efficient DNA-directed quenching of polyfluorene fluorescence was shown. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

    Science.gov (United States)

    Sreeram, Arvind

    Conjugated polymers have found several applications in recent years, in energy conversion and storage devices such as organic light emitting diodes, solar cells, batteries, and super capacitors. Thin films of polymers used for these applications need to be mechanically and thermally stable to withstand the harsh operating conditions. Although there is significant information on the optoelectronic properties of many of these polymers, there are only few studies on their mechanical properties. There is little information in the literature on how processing of these films influence mechanical properties. In the first part of this study, poly(p-phenylene vinylene) (PPV) films were prepared by thermolytic conversion of poly[p -phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures and the kinetics of reaction was investigated using thermogravimetry and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties of the films, studied using nanoindentation, showed a dependence on the extent of conversion and chemical composition of the films. The presence of chemical defects (e.g., carbonyl groups, detected using FTIR spectroscopy), was also found to have a noticeable effect on the modulus and hardness of the films. The storage modulus, E', and plasticity decreased with an increase in conversion, whereas the loss modulus, E", showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E" than E', consistent with the glassy nature of the polymers at room temperature. In the second part of the study, polyacetylene films were synthesized by acid-catalyzed dehydration reaction of poly(vinyl alcohol) (PVA) precursor films. The kinetics of this reaction was monitored by thermogravimetry. The chemical structure of the conjugated polymer films was characterized by Raman and IR spectroscopy. Polyacetylene films incorporated with 1-propyl-3-methylimidazolium ionic liquid

  8. High-Performance Single-Crystalline Perovskite Thin-Film Photodetector

    KAUST Repository

    Yang, Zhenqian; Deng, Yuhao; Zhang, Xiaowei; Wang, Suo; Chen, Huazhou; Yang, Sui; Khurgin, Jacob; Fang, Nicholas X.; Zhang, Xiang; Ma, Renmin

    2018-01-01

    The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial

  9. Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

    Science.gov (United States)

    Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

    2012-01-01

    In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE

  10. Recent Advances in Gas Barrier Thin Films via Layer-by-Layer Assembly of Polymers and Platelets.

    Science.gov (United States)

    Priolo, Morgan A; Holder, Kevin M; Guin, Tyler; Grunlan, Jaime C

    2015-05-01

    Layer-by-layer (LbL) assembly has emerged as the leading non-vacuum technology for the fabrication of transparent, super gas barrier films. The super gas barrier performance of LbL deposited films has been demonstrated in numerous studies, with a variety of polyelectrolytes, to rival that of metal and metal oxide-based barrier films. This Feature Article is a mini-review of LbL-based multilayer thin films with a 'nanobrick wall' microstructure comprising polymeric mortar and nano-platelet bricks that impart high gas barrier to otherwise permeable polymer substrates. These transparent, water-based thin films exhibit oxygen transmission rates below 5 × 10(-3) cm(3) m(-2) day(-1) atm(-1) and lower permeability than any other barrier material reported. In an effort to put this technology in the proper context, incumbent technologies such as metallized plastics, metal oxides, and flake-filled polymers are briefly reviewed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fast polymer nanorectifiers for inductively coupled RFID tags

    International Nuclear Information System (INIS)

    Majewski, L.A.; Balocco, C.; King, R.; Whitelegg, S.; Song, A.M.

    2008-01-01

    In this article, an alternative approach to high switching speed organic rectifiers based on a semiconducting polymer, poly(dialkylquarterthiophene) (PQT-12) is demonstrated. It is shown that by using a linear array of polymer nanowires with intentionally broken symmetry, nanodevices displaying diode-like I/V characteristics can be obtained. The so-called self-switching devices (SSDs) are single-layered planar structures that can be easily fabricated in a single step of nanolithography. In addition, since SSD arrays possess substantially lower parasitic capacitance between contacts than conventional vertical organic diodes (VODs) and organic thin-film transistors (OTFTs), very high switching speeds may be achieved. As the result of this combination of favourable properties, we have demonstrated polymer nanorectifiers operating with frequencies well in excess of 1 MHz that have the potential to pave the way towards ultra low-cost radio frequency identification (RFID) tags

  12. Cell behaviors on micro-patterned porous thin films

    International Nuclear Information System (INIS)

    Phong, Ho Quoc; Wang Shuling; Wang, Meng-Jiy

    2010-01-01

    Thin polymer films with patterned surfaces have drawn tremendous attention in manufacturing advanced electronic, mechanical devices and in biomaterials due to the advantageous properties such as mechanical strength, chemical resistance and optic transparency. The applications can be extended to the fields such as catalysts, antireflection coatings, template for inorganic growth masks, and substrates for cell culturing providing the patterned surface containing micron-sized features. Various methods have been used to fabricate polymers with micro-patterned surfaces such as photolithographic, ink-jet printing, nonsolvent, spin coating in a dry environment, self-organization, and the condensation of monodisperse water droplet on the polymer solution. The physiological functions of mature cells depend on the microenvironment/niche surrounding which can provide proper factors to regulate cell proliferation and differentiation. While designing appropriate scaffolds for tissue engineering, the microstructure is one of the most important factors to be considered. In this work, a facile single-step phase separation method was used to create micro-patterned polymer thin films with concaves or convexes with sizes ranged from 7 to 70 μm. The effects of water content, casting volume and the addition of surfactant on the distribution of pores and substrate morphology were examined. Moreover, detailed observations of fibroblast cells on the micro-patterned thin films were presented to compare and elucidate the roles of surface micro-features and chemical functionalities.

  13. Real-time observation of conformational switching in single conjugated polymer chains.

    Science.gov (United States)

    Tenopala-Carmona, Francisco; Fronk, Stephanie; Bazan, Guillermo C; Samuel, Ifor D W; Penedo, J Carlos

    2018-02-01

    Conjugated polymers (CPs) are an important class of organic semiconductors that combine novel optoelectronic properties with simple processing from organic solvents. It is important to study CP conformation in solution to understand the physics of these materials and because it affects the properties of solution-processed films. Single-molecule techniques are unique in their ability to extract information on a chain-to-chain basis; however, in the context of CPs, technical challenges have limited their general application to host matrices or semiliquid environments that constrain the conformational dynamics of the polymer. We introduce a conceptually different methodology that enables measurements in organic solvents using the single-end anchoring of polymer chains to avoid diffusion while preserving polymer flexibility. We explore the effect of organic solvents and show that, in addition to chain-to-chain conformational heterogeneity, collapsed and extended polymer segments can coexist within the same chain. The technique enables real-time solvent-exchange measurements, which show that anchored CP chains respond to sudden changes in solvent conditions on a subsecond time scale. Our results give an unprecedented glimpse into the mechanism of solvent-induced reorganization of CPs and can be expected to lead to a new range of techniques to investigate and conformationally manipulate CPs.

  14. Confinement induced ordering in dewetting of ultra-thin polymer bilayers on nanopatterned substrates.

    Science.gov (United States)

    Bhandaru, Nandini; Das, Anuja; Mukherjee, Rabibrata

    2016-01-14

    We report the dewetting of a thin bilayer of polystyrene (PS) and poly(methylmethacrylate) (PMMA) on a topographically patterned nonwettable substrate comprising an array of pillars, arranged in a square lattice. With a gradual increase in the concentration of the PMMA solution (Cn-PMMA), the morphology of the bottom layer changes to: (1) an aligned array of spin dewetted droplets arranged along substrate grooves at very low Cn-PMMA; (2) an interconnected network of threads surrounding each pillar at intermediate Cn-PMMA; and (3) a continuous bottom layer at higher Cn-PMMA. On the other hand the morphology of the PS top layer depends largely on the nature of the pre-existing bottom layer, in addition to Cn-PS. An ordered array of PMMA core-PS shell droplets forms right after spin coating when both Cn-PMMA and Cn-PS are very low. Bilayers with all other initial configurations evolve during thermal annealing, resulting in a variety of ordered structures. Unique morphologies realized include laterally coexisting structures of the two polymers confined within the substrate grooves due to initial rupture of the bottom layer on the substrate followed by a squeezing flow of the top layer; an array of core-shell and single polymer droplets arranged in an alternating order etc., to highlight a few. Such structures cannot be fabricated by any stand-alone lithography technique. On the other hand, in some cases the partially dewetted bottom layer imparts stability to an intact top PS layer against dewetting. Apart from ordering, under certain specific conditions significant miniaturization and downsizing of dewetted feature periodicity and dimension as compared to dewetting of a single layer on a flat substrate is observed. With the help of a morphology phase diagram we show that ordering is achieved over a wide combination of Cn-PMMA and Cn-PS, though the morphology and dewetting pathway differs significantly with variation in the thickness of the individual layers.

  15. Spin coating of an evaporating polymer solution

    KAUST Repository

    Münch, Andreas

    2011-01-01

    We consider a mathematical model of spin coating of a single polymer blended in a solvent. The model describes the one-dimensional development of a thin layer of the mixture as the layer thins due to flow created by a balance of viscous forces and centrifugal forces and evaporation of the solvent. In the model both the diffusivity of the solvent in the polymer and the viscosity of the mixture are very rapidly varying functions of the solvent mass fraction. Guided by numerical solutions an asymptotic analysis reveals a number of different possible behaviours of the thinning layer dependent on the nondimensional parameters describing the system. The main practical interest is in controlling the appearance and development of a "skin" on the polymer where the solvent concentration reduces rapidly on the outer surface leaving the bulk of the layer still with high concentrations of solvent. In practice, a fast and uniform drying of the film is required. The critical parameters controlling this behaviour are found to be the ratio of the diffusion to advection time scales ε, the ratio of the evaporation to advection time scales δ and the ratio of the diffusivity of the pure polymer and the initial mixture exp(-1/γ). In particular, our analysis shows that for very small evaporation with δ

  16. Sm-doped CeO2 single buffer layer for YBCO coated conductors by polymer assisted chemical solution deposition (PACSD) method

    International Nuclear Information System (INIS)

    Li, G.; Pu, M.H.; Sun, R.P.; Wang, W.T.; Wu, W.; Zhang, X.; Yang, Y.; Cheng, C.H.; Zhao, Y.

    2008-01-01

    An over 150 nm thick Sm 0.2 Ce 0.8 O 1.9-x (SCO) single buffer layer has been deposited on bi-axially textured NiW (2 0 0) alloy substrate. Highly in-plane and out-of-plane oriented, dense, smooth and crack free SCO single layer has been obtained via a polymer-assisted chemical solution deposition (PACSD) approach. YBCO thin film has been deposited equally via a PACSD route on the SCO-buffered NiW, the as grown YBCO yielding a sharp transition at T c0 = 87 K as well as J c (0 T, 77 K) ∼ 1 MA/cm 2 . These results indicates that RE (lanthanides other than Ce) doping may be an effective approach to improve the critical thickness of solution derived CeO 2 film, which renders it a promising candidate as single buffer layer for YBCO coated conductors

  17. Dewetting of polymer thin films on modified curved surfaces: preparation of polymer nanoparticles with asymmetric shapes by anodic aluminum oxide templates.

    Science.gov (United States)

    Liu, Chih-Ting; Tsai, Chia-Chan; Chu, Chien-Wei; Chi, Mu-Huan; Chung, Pei-Yun; Chen, Jiun-Tai

    2018-04-18

    We study the dewetting behaviors of poly(methyl methacrylate) (PMMA) thin films coated in the cylindrical nanopores of anodic aluminum oxide (AAO) templates by thermal annealing. Self-assembled monolayers (SAMs) of n-octadecyltrichlorosilane (ODTS) are introduced to modify the pore surfaces of the AAO templates to induce the dewetting process. By using scanning electron microscopy (SEM), the dewetting-induced morphology transformation from the PMMA thin films to PMMA nanoparticles with asymmetric shapes can be observed. The sizes of the PMMA nanoparticles can be controlled by the original PMMA solution concentrations. The dewetting phenomena on the modified nanopores are explained by taking into account the excess intermolecular interaction free energy (ΔG). This work opens a new possibility for creating polymer nanoparticles with asymmetric shapes in confined geometries.

  18. Local variation of fragility and glass transition temperature of ultra-thin supported polymer films.

    Science.gov (United States)

    Hanakata, Paul Z; Douglas, Jack F; Starr, Francis W

    2012-12-28

    Despite extensive efforts, a definitive picture of the glass transition of ultra-thin polymer films has yet to emerge. The effect of film thickness h on the glass transition temperature T(g) has been widely examined, but this characterization does not account for the fragility of glass-formation, which quantifies how rapidly relaxation times vary with temperature T. Accordingly, we simulate supported polymer films of a bead-spring model and determine both T(g) and fragility, both as a function of h and film depth. We contrast changes in the relaxation dynamics with density ρ and demonstrate the limitations of the commonly invoked free-volume layer model. As opposed to bulk polymer materials, we find that the fragility and T(g) do not generally vary proportionately. Consequently, the determination of the fragility profile--both locally and for the film as a whole--is essential for the characterization of changes in film dynamics with confinement.

  19. Fabrication and performance of polymer-nanocomposite anti-reflective thin films deposited by RIR-MAPLE

    Energy Technology Data Exchange (ETDEWEB)

    Singaravelu, S.; Mayo, D. C.; Park, H-. K.; Schriver, K. E.; Klopf, John M. [W& M, JLAB; Kelley, Michael J. [W& M; Haglund, R. F. [VANDERBILT

    2014-07-01

    Design of polymer anti-reflective (AR) optical coatings for plastic substrates is challenging because polymers exhibit a relatively narrow range of refractive indices. Here, we report synthesis of a four-layer AR stack using hybrid polymer: nanoparticle materials deposited by resonant infrared matrix-assisted pulsed laser evaporation. An Er: YAG laser ablated frozen solutions of a high-index composite containing TiO2 nanoparticles and poly(methylmethacrylate) (PMMA), alternating with a layer of PMMA. The optimized AR coatings, with thicknesses calculated using commercial software, yielded a coating for polycarbonate with transmission over 97 %, scattering <3 %, and a reflection coefficient below 0.5 % across the visible range, with a much smaller number of layers than would be predicted by a standard thin film calculation. The TiO2 nanoparticles contribute more to the enhanced refractive index of the high-index layers than can be accounted for by an effective medium model of the nanocomposite.

  20. Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

    KAUST Repository

    Mei, Jianguo

    2011-12-21

    We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1), was obtained from solution-processed thin-film transistors, one of the highest mobilities reported to date. In contrast, the reference polymer with a branched alkyl side chain gave an average hole mobility of 0.30 cm 2 V -1 s -1 and a maximum mobility of 0.57 cm 2 V -1 s -1. This is largely explained by the polymer packing: our new polymer exhibited a π-π stacking distance of 3.58 Å, while the reference polymer showed a distance of 3.76 Å. © 2011 American Chemical Society.

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

    International Nuclear Information System (INIS)

    Ben Dkhil, S.; Bourguiga, R.; Davenas, J.; Cornu, D.

    2012-01-01

    Highlights: ► Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. ► We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. ► The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. ► 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 oc and short-circuit current density J 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.

  2. The scanning probe microscopy study of thin polymer films

    International Nuclear Information System (INIS)

    Harron, H.R.

    1995-08-01

    Scanning Tunnelling Microscopy and Atomic Force Microscopy were used systematically to investigate the morphology, uniformity, coverage and structure of the thin films of several commercially important insulating polymers. Despite the poorly conducting nature of the polymer sample, detailed and convincing images of this class of materials were achieved by STM without the need to coat the samples with a conductive layer. The polymer regions of the sample were further investigated by the use of surface profiling with 'line scans'. The fluctuations of the amplitude therein enabled important film characteristics to be assessed. An environmental stage was designed for the STM to enable the effect of various vapour-sample interactions to be observed during the imaging process. Using the data from the environmental stage in addition to the surface profiling with line scans, an insight into the conduction mechanism and image interpretation was gained. Results suggest that the water content of the sample and its immediate surroundings is an important factor in achieving reliable STM images in air. The initial study culminated with the observation by STM alone of the plasticizer induced crystallization of uncoated PC thin films. The 'amorphous' PC films were observed before crystallization and small ordered regions in roughly the same proportion as that predicted by diffraction studies [Prietschk, 1959 and Schnell, 1964] were imaged. This has never been observed by a microscopy technique. Furthermore, images of the crystalline film contained elongated units that were attributed to the lamellae formations that form the basic building blocks of polymer spherulites. The study continued with the AFM imaging of the growth of crystalline entities in a PC film, without the need for harsh sample treatment or metal coating. A method of casting and crystallizing the films was developed such that the growth was predominantly in two dimensions and consequently ideal for observation by

  3. Molecular dynamics simulation of AFM studies of a single polymer chain

    International Nuclear Information System (INIS)

    Wang Wenhai; Kistler, Kurt A.; Sadeghipour, Keya; Baran, George

    2008-01-01

    Single polymer chain force-extension behavior measured by Atomic Force Microscopy (AFM) was interpreted by molecular dynamics (MD) simulation performed by applying a bead-spring (coarse-graining) model in which the bond potential function between adjacent beads is described by a worm-like chain (WLC) model. Simulation results indicate that caution should be applied when interpreting experimental AFM data, because the data vary depending on the point of AFM tip-polymer chain attachment. This approach offers an effective way for eventual analysis of the mechanical behavior of complex polymer networks

  4. Molecular dynamics simulation of AFM studies of a single polymer chain

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wenhai [Center for Bioengineering and Biomaterials, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122 (United States); Kistler, Kurt A. [Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122 (United States); Sadeghipour, Keya [Center for Bioengineering and Biomaterials, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122 (United States); Baran, George [Center for Bioengineering and Biomaterials, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122 (United States)], E-mail: grbaran@temple.edu

    2008-11-24

    Single polymer chain force-extension behavior measured by Atomic Force Microscopy (AFM) was interpreted by molecular dynamics (MD) simulation performed by applying a bead-spring (coarse-graining) model in which the bond potential function between adjacent beads is described by a worm-like chain (WLC) model. Simulation results indicate that caution should be applied when interpreting experimental AFM data, because the data vary depending on the point of AFM tip-polymer chain attachment. This approach offers an effective way for eventual analysis of the mechanical behavior of complex polymer networks.

  5. Polymer relaxations in thin films in the vicinity of a penetrant or a temperature induced glass transition

    NARCIS (Netherlands)

    Ogieglo, Wojciech; Wessling, Matthias; Benes, Nieck Edwin

    2014-01-01

    The transient properties of thin glassy polymer films in the vicinity of the glass transition are investigated. We compare the differences and similarities between sorption and temperature induced glass transitions, referred to as Pg and Tg, respectively. The experimental technique used is in situ

  6. Prediction of crack density and electrical resistance changes in indium tin oxide/polymer thin films under tensile loading

    KAUST Repository

    Mora Cordova, Angel; Khan, Kamran; El Sayed, Tamer

    2014-01-01

    We present unified predictions for the crack onset strain, evolution of crack density, and changes in electrical resistance in indium tin oxide/polymer thin films under tensile loading. We propose a damage mechanics model to quantify and predict

  7. Phase transitions of single polymer chains and of polymer solutions: insights from Monte Carlo simulations

    International Nuclear Information System (INIS)

    Binder, K; Paul, W; Strauch, T; Rampf, F; Ivanov, V; Luettmer-Strathmann, J

    2008-01-01

    The statistical mechanics of flexible and semiflexible macromolecules is distinct from that of small molecule systems, since the thermodynamic limit can also be approached when the number of (effective) monomers of a single chain (realizable by a polymer solution in the dilute limit) is approaching infinity. One can introduce effective attractive interactions into a simulation model for a single chain such that a swollen coil contracts when the temperature is reduced, until excluded volume interactions are effectively canceled by attractive forces, and the chain conformation becomes almost Gaussian at the theta point. This state corresponds to a tricritical point, as the renormalization group theory shows. Below the theta temperature a fluid globule is predicted (at nonzero concentration then phase separation between dilute and semidilute solutions occurs), while at still lower temperature a transition to a solid phase (crystal or glass) occurs. Monte Carlo simulations have shown, however, that the fluid globule phase may become suppressed, when the range of the effective attractive forces becomes too short, with the result that a direct (ultimately first-order) transition from the swollen coil to the solid occurs. This behavior is analogous to the behavior of colloidal particles with a very short range of attractive forces, where liquid-vapor-type phase separation may be suppressed. Analogous first-order transitions from swollen coils to dense rodlike or toroidal structures occur for semiflexible polymers. Finally, the modifications of the behavior discussed when the polymers are adsorbed at surfaces are also mentioned, and possible relations to wetting behavior of polymer solutions are addressed.

  8. Identification and design of novel polymer-based mechanical transducers: A nano-structural model for thin film indentation

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J., E-mail: dsirbuly@ucsd.edu [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States)

    2014-09-14

    Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.

  9. Identification and design of novel polymer-based mechanical transducers: A nano-structural model for thin film indentation

    International Nuclear Information System (INIS)

    Villanueva, Joshua; Huang, Qian; Sirbuly, Donald J.

    2014-01-01

    Mechanical characterization is important for understanding small-scale systems and developing devices, particularly at the interface of biology, medicine, and nanotechnology. Yet, monitoring sub-surface forces is challenging with current technologies like atomic force microscopes (AFMs) or optical tweezers due to their probe sizes and sophisticated feedback mechanisms. An alternative transducer design relying on the indentation mechanics of a compressible thin polymer would be an ideal system for more compact and versatile probes, facilitating measurements in situ or in vivo. However, application-specific tuning of a polymer's mechanical properties can be burdensome via experimental optimization. Therefore, efficient transducer design requires a fundamental understanding of how synthetic parameters such as the molecular weight and grafting density influence the bulk material properties that determine the force response. In this work, we apply molecular-level polymer scaling laws to a first order elastic foundation model, relating the conformational state of individual polymer chains to the macroscopic compression of thin film systems. A parameter sweep analysis was conducted to observe predicted model trends under various system conditions and to understand how nano-structural elements influence the material stiffness. We validate the model by comparing predicted force profiles to experimental AFM curves for a real polymer system and show that it has reasonable predictive power for initial estimates of the force response, displaying excellent agreement with experimental force curves. We also present an analysis of the force sensitivity of an example transducer system to demonstrate identification of synthetic protocols based on desired mechanical properties. These results highlight the usefulness of this simple model as an aid for the design of a new class of compact and tunable nanomechanical force transducers.

  10. Optical measuring system with an interrogator and a polymer-based single-mode fibre optic sensor system

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor...... system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives...

  11. Scalability and stability of very thin roll-to-roll processed large area indium-tin-oxide free polymer solar cell modules

    DEFF Research Database (Denmark)

    Angmo, Dechan; Gevorgyan, Suren; Larsen-Olsen, Thue Trofod

    2013-01-01

    Polymer solar cell modules were prepared directly on thin flexible barrier polyethylene terephthalate foil. The performance of the modules was found to be scalable from a single cell with an area of 6 cm2 to modules with a total area of up to 186 cm2. The substrate thickness was also explored...... employing P3HT:PCBM as the active material and were found to exhibit a total area efficiency of >1% (1000 W/m2; AM1.5G) with a typical active-area efficiency in the 1.5–1.6% for total module area of >110 cm2 due to high fill factors in excess of 50%. The modules were also found to have an active...

  12. Single mode dye-doped polymer photonic crystal lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode...... emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e. g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be -0.045 or -0...

  13. Numerical study on injection parameters optimization of thin wall and biodegradable polymers parts

    Science.gov (United States)

    Santos, C.; Mendes, A.; Carreira, P.; Mateus, A.; Malça, C.

    2017-07-01

    Nowadays, the molds industry searches new markets, with diversified and added value products. The concept associated to the production of thin walled and biodegradable parts mostly manufactured by injection process has assumed a relevant importance due to environmental and economic factors. The growth of a global consciousness about the harmful effects of the conventional polymers in our life quality associated with the legislation imposed, become key factors for the choice of a particular product by the consumer. The target of this work is to provide an integrated solution for the injection of parts with thin walls and manufactured using biodegradable materials. This integrated solution includes the design and manufacture processes of the mold as well as to find the optimum values for the injection parameters in order to become the process effective and competitive. For this, the Moldflow software was used. It was demonstrated that this computational tool provides an effective responsiveness and it can constitute an important tool in supporting the injection molding of thin-walled and biodegradable parts.

  14. Polymer and organic solar cells viewed as thin film technologies: What it will take for them to become a success outside academia

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Jørgensen, Mikkel

    2013-01-01

    The polymer and organic solar cell technology is critically presented in the context of other thin film technologies with a specific focus on what it will take to make them a commercial success. The academic success of polymer and organic solar cells far outweigh any other solar cell technology w...

  15. Protein immobilization on epoxy-activated thin polymer films: effect of surface wettability and enzyme loading.

    Science.gov (United States)

    Chen, Bo; Pernodet, Nadine; Rafailovich, Miriam H; Bakhtina, Asya; Gross, Richard A

    2008-12-02

    A series of epoxy-activated polymer films composed of poly(glycidyl methacrylate/butyl methacrylate/hydroxyethyl methacrylate) were prepared. Variation in comonomer composition allowed exploration of relationships between surface wettability and Candida antartica lipase B (CALB) binding to surfaces. By changing solvents and polymer concentrations, suitable conditions were developed for preparation by spin-coating of uniform thin films. Film roughness determined by AFM after incubation in PBS buffer for 2 days was less than 1 nm. The occurrence of single CALB molecules and CALB aggregates at surfaces was determined by AFM imaging and measurements of volume. Absolute numbers of protein monomers and multimers at surfaces were used to determine values of CALB specific activity. Increased film wettability, as the water contact angle of films increased from 420 to 550, resulted in a decreased total number of immobilized CALB molecules. With further increases in the water contact angle of films from 55 degrees to 63 degrees, there was an increased tendency of CALB molecules to form aggregates on surfaces. On all flat surfaces, two height populations, differing by more than 30%, were observed from height distribution curves. They are attributed to changes in protein conformation and/or orientation caused by protein-surface and protein-protein interactions. The fraction of molecules in these populations changed as a function of film water contact angle. The enzyme activity of immobilized films was determined by measuring CALB-catalyzed hydrolysis of p-nitrophenyl butyrate. Total enzyme specific activity decreased by decreasing film hydrophobicity.

  16. Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

    Science.gov (United States)

    Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

    2017-10-25

    Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

  17. Whole field strain measurement in critical thin adhesive layer of single- and double-sided repaired CFRP panel using DIC

    Science.gov (United States)

    Kashfuddoja, Mohammad; Ramji, M.

    2015-03-01

    In the present work, the behavior of thin adhesively layer in patch repaired carbon fiber reinforced polymer (CFRP) panel under tensile load is investigated experimentally using digital image correlation (DIC) technique. The panel is made of Carbon/epoxy composite laminate and the stacking sequence in the panel is [0º]4. A circular hole of 10 mm diameter (d) is drilled at the center of the panel to mimic the case of low velocity impact damage removal. The panel with open hole is repaired with double sided (symmetrical) and single sided (unsymmetrical) rectangular patch made of same panel material having stacking sequence of [0º]3. Araldite 2011 is used for bonding the patch onto the panel over the damaged area. The global behavior of thin adhesive layer is examined by analyzing whole field strain distribution using DIC. Longitudinal, peel and shear strain field in both double and single sided repair configuration is studied and a compression is made between them. An estimate of shear transfer length which is an essential parameter in arriving at an appropriate overlap length in patch design is proposed from DIC and FEA. Damage development, failure mechanism and load displacement behavior is also investigated. The experimental results are compared with the numerical predictions.

  18. Surface analysis of the selective excimer laser patterning of a thin PEDOT:PSS film on flexible polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Schaubroeck, David, E-mail: David.Schaubroeck@elis.ugent.be [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium); De Smet, Jelle; Willems, Wouter [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium); Cools, Pieter; De Geyter, Nathalie; Morent, Rino [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); De Smet, Herbert; Van Steenbeerge, Geert [Center for Microsystems Technology (CMST), imec and Ghent University, Technologiepark 15, B-9052 Ghent (Belgium)

    2016-07-15

    Highlights: • Laser patterning of thin film PEDOT:PSS on polymer foils is characterized in great detail. • PEDOT:PSS does not need to be fully removed to create electrically insulating patterns. • The underlying polymer foil influences the ablation behavior. - Abstract: Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

  19. Low-power logic computing realized in a single electric-double-layer MoS2 transistor gated with polymer electrolyte

    Science.gov (United States)

    Guo, Junjie; Xie, Dingdong; Yang, Bingchu; Jiang, Jie

    2018-06-01

    Due to its mechanical flexibility, large bandgap and carrier mobility, atomically thin molybdenum disulphide (MoS2) has attracted widespread attention. However, it still lacks a facile route to fabricate a low-power high-performance logic gates/circuits before it gets the real application. Herein, we reported a facile and environment-friendly method to establish the low-power logic function in a single MoS2 field-effect transistor (FET) configuration gated with a polymer electrolyte. Such low-power and high-performance MoS2 FET can be implemented by using water-soluble polyvinyl alcohol (PVA) polymer as proton-conducting electric-double-layer (EDL) dielectric layer. It exhibited an ultra-low voltage (1.5 V) and a good performance with a high current on/off ratio (Ion/off) of 1 × 105, a large electron mobility (μ) of 47.5 cm2/V s, and a small subthreshold swing (S) of 0.26 V/dec, respectively. The inverter can be realized by using such a single MoS2 EDL FET with a gain of ∼4 at the operation voltage of only ∼1 V. Most importantly, the neuronal AND logic computing can be also demonstrated by using such a double-lateral-gate single MoS2 EDL transistor. These results show an effective step for future applications of 2D MoS2 FETs for integrated electronic engineering and low-energy environment-friendly green electronics.

  20. Surface characterization of selected polymer thin films by total-reflection x-ray fluorescence spectroscopy and x-ray reflectivity

    International Nuclear Information System (INIS)

    Innis, Vallerie Ann A.

    2006-01-01

    Development of available x-ray characterizations tools for grazing incidence techniques was done to be able to probe nano-size thin films. Alignment of a Philips x-ray powder diffractometer was improved to let it perform as an x-ray reflectometer. X-ray reflectometry was coupled with total-reflection x-ray fluorescence spectroscopy. Evaluation of the performance of this grazing incidence techniques was done by preparing polymer thin films of carboxymethylcellulose, carrageenan and polyvinylpyrrolidone (PVP). The thickness of the films were varied by varying the process parameters such as concentration, spin speed and spin time. Angle-dispersive total-reflection x-ray fluorescence spectroscopy profiles of three films showed film formation only in carrageenan and PVP. For both carrageenan and PVP, an increase in concentration yielded a corresponding increase in intensity of the fluorescent or scattered peaks. XRR profiles of carrageenan thin films yielded a mean value for the critical angle close to quartz substrate. Thickness measurements of the prepared carrageenan thin films showed that concentration was the main determinant for final film thickness over the other process parameters. Sulfur fluorescent intensity derived from the TXRF measurement showed a linear relationship with the measured thickness by XRR. For PVP, measured critical angle is lower than quartz. Poor adhesion of the polymer onto the substrate yielded a limited number of thickness measurements made from the XRR profiles. (Author)

  1. Epitaxial Lift-Off of Centimeter-Scaled Spinel Ferrite Oxide Thin Films for Flexible Electronics.

    Science.gov (United States)

    Shen, Lvkang; Wu, Liang; Sheng, Quan; Ma, Chunrui; Zhang, Yong; Lu, Lu; Ma, Ji; Ma, Jing; Bian, Jihong; Yang, Yaodong; Chen, Aiping; Lu, Xiaoli; Liu, Ming; Wang, Hong; Jia, Chun-Lin

    2017-09-01

    Mechanical flexibility of electronic devices has attracted much attention from research due to the great demand in practical applications and rich commercial value. Integration of functional oxide materials in flexible polymer materials has proven an effective way to achieve flexibility of functional electronic devices. However, the chemical and mechanical incompatibilities at the interfaces of dissimilar materials make it still a big challenge to synthesize high-quality single-crystalline oxide thin film directly on flexible polymer substrates. This study reports an improved method that is employed to successfully transfer a centimeter-scaled single-crystalline LiFe 5 O 8 thin film on polyimide substrate. Structural characterizations show that the transferred films have essentially no difference in comparison with the as-grown films with respect to the microstructure. In particular, the transferred LiFe 5 O 8 films exhibit excellent magnetic properties under various mechanical bending statuses and show excellent fatigue properties during the bending cycle tests. These results demonstrate that the improved transfer method provides an effective way to compose single-crystalline functional oxide thin films onto flexible substrates for applications in flexible and wearable electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Laser Deposition of Polymer Nanocomposite Thin Films and Hard Materials and Their Optical Characterization

    Science.gov (United States)

    2013-12-05

    visible light on instruments such as microscope tips and micro- surgical tools. Hard carbon known as diamond-like carbon films produced by pulsed laser ...visible (610 nm) LED source and a supplemental infra-red 980-nm laser diode (for the studies of the upconversion fluorescence). The basic package...5/2013 Final Performance Report 15 Sep 2012- 14 Sep 2013 LASER DEPOSITION OF POLYMER NANOCOMPOSITE THIN FILMS AND HARD MATERIALS AND THEIR OPTICAL

  3. Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers.

    Science.gov (United States)

    Buck, Maren E; Schwartz, Sarina C; Lynn, David M

    2010-09-11

    We report an approach to the fabrication of superhydrophobic thin films that is based on the 'reactive' layer-by-layer assembly of azlactone-containing polymer multilayers. We demonstrate that films fabricated from alternating layers of the azlactone functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and poly(ethyleneimine) (PEI) exhibit micro- and nanoscale surface features that result in water contact angles in excess of 150º. Our results reveal that the formation of these surface features is (i) dependent upon film thickness (i.e., the number of layers of PEI and PVDMA deposited) and (ii) that it is influenced strongly by the presence (or absence) of cyclic azlactone-functionalized oligomers that can form upon storage of the 2-vinyl-4,4-dimethylazlactone (VDMA) used to synthesize PVDMA. For example, films fabricated using polymers synthesized in the presence of these oligomers exhibited rough, textured surfaces and superhydrophobic behavior (i.e., advancing contact angles in excess of 150º). In contrast, films fabricated from PVDMA polymerized in the absence of this oligomer (e.g., using freshly distilled monomer) were smooth and only moderately hydrophobic (i.e., advancing contact angles of ~75º). The addition of authentic, independently synthesized oligomer to samples of distilled VDMA at specified and controlled concentrations permitted reproducible fabrication of superhydrophobic thin films on the surfaces of a variety of different substrates. The surfaces of these films were demonstrated to be superhydrophobic immediately after fabrication, but they became hydrophilic after exposure to water for six days. Additional experiments demonstrated that it was possible to stabilize and prolong the superhydrophobic properties of these films (e.g., advancing contact angles in excess of 150° even after complete submersion in water for at least six weeks) by exploiting the reactivity of residual azlactones to functionalize the surfaces of the films

  4. Tunable Gas Permeability of Polymer-Clay Nano Brick Wall Thin Film Assemblies

    Science.gov (United States)

    Gamboa, Daniel; Priolo, Morgan; Grunlan, Jaime

    2010-03-01

    Thin films of anionic natural montmorrilonite (MMT) clay and cationic polyethylenimine (PEI) have been produced by alternately dipping a plastic substrate into dilute aqueous mixtures containing each ingredient. After 40 polymer-clay layers have been deposited, the resulting transparent film exhibits an oxygen transmission rate (OTR) below 0.35 cm^3/m^2 . day when the pH of PEI solution is 10. This low permeability is due to a brick wall nanostructure comprised of completely exfoliated clay bricks in polymeric mortar. This brick wall creates an extremely tortuous path at thicknesses below 250 nm and clay concentration above 80 wt%. A 70-bilayer PEI-MMT assembly has an undetectable OTR (< 0.005 cm^3/m^2 . day), which equates to a permeability below SiOx when multiplied by its film thickness of 231 nm. With optical transparency greater than 86% and the ability to be microwaved, these thin film composites are good candidates for flexible electronics packaging and foil replacement for food.

  5. Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

    Science.gov (United States)

    Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

    A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

  6. Transparent indium zinc oxide thin films used in photovoltaic cells based on polymer blends

    International Nuclear Information System (INIS)

    Besleaga, Cristina; Ion, L.; Ghenescu, Veta; Socol, G.; Radu, A.; Arghir, Iulia; Florica, Camelia; Antohe, S.

    2012-01-01

    Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were prepared by ablation of targets with In concentrations, In/(In + Zn), of 80 at.%, at low substrate temperatures under reactive atmosphere. IZO films were used as transparent electrodes in polymer-based – poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 1:1 blend – photovoltaic cells. The action spectra measurements revealed that IZO-based photovoltaic structures have performances comparable with those using indium–tin–oxide as transparent electrode. - Highlights: ► Indium zinc oxide films were grown by pulsed laser deposition at room temperature. ► The films had large free carrier density and reasonably high mobility. ► These films fit for transparent electrodes in polymer-based photovoltaic cells.

  7. Single mode dye-doped polymer photonic crystal lasers

    International Nuclear Information System (INIS)

    Christiansen, Mads B; Buß, Thomas; Smith, Cameron L C; Petersen, Sidsel R; Jørgensen, Mette M; Kristensen, Anders

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e.g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be −0.045 or −0.066 nm K -1 , depending on the material

  8. Synthesis of Acenaphthyl and Phenanthrene Based Fused-Aromatic Thienopyrazine Co-Polymers for Photovoltaic and Thin Film Transistor Applications

    KAUST Repository

    Mondal, Rajib

    2009-08-11

    Dithiophene and fluorene co-polymers containing fused aromatic thieno[3,4-b]pyrazine moieties were synthesized for organic thin film transistor (OTFT) and organic photovoltaic (OPV) applications. Suzuki and Stille polycondensation reactions were used for the polymerization. The band gap (Eg) of the polymers was tuned in the range of 1.15-1.6 eV to match the solar spectrum. Density functional theory calculations were carried out to rationalize the low band gaps. These polymers showed field effect mobility (μ) as high as 0.2 cm2/(V.s) with an on/off ratio as high as 106 in OTFT devices. Interestingly, one polymer in this class also showed ambipolar charge transport. Power conversion efficiency (PCE) up to 1.3% was achieved in bulk heterojunction solar cells, indicating that these materials are promising for OPV applications. © 2009 American Chemical Society.

  9. Analysis of thin-film polymers using attenuated total internal reflection-Raman microspectroscopy.

    Science.gov (United States)

    Tran, Willie; Tisinger, Louis G; Lavalle, Luis E; Sommer, André J

    2015-01-01

    Two methods commonly employed for molecular surface analysis and thin-film analysis of microscopic areas are attenuated total reflection infrared (ATR-IR) microspectroscopy and confocal Raman microspectroscopy. In the former method, the depth of the evanescent probe beam can be controlled by the wavelength of light, the angle of incidence, or the refractive index of the internal reflection element. Because the penetration depth is proportional to the wavelength of light, one could interrogate a smaller film thickness by moving from the mid-infrared region to the visible region employing Raman spectroscopy. The investigation of ATR Raman microspectroscopy, a largely unexplored technique available to Raman microspectroscopy, was carried out. A Renishaw inVia Raman microscope was externally modified and used in conjunction with a solid immersion lens (SIL) to perform ATR Raman experiments. Thin-film polymer samples were analyzed to explore the theoretical sampling depth for experiments conducted without the SIL, with the SIL, and with the SIL using evanescent excitation. The feasibility of micro-ATR Raman was examined by collecting ATR spectra from films whose thickness measured from 200 to 60 nm. Films of these thicknesses were present on a much thicker substrate, and features from the underlying substrate did not become visible until the thin film reached a thickness of 68 nm.

  10. Efficient Synthesis of Single-Chain Polymer Nanoparticles via Amide Formation

    Directory of Open Access Journals (Sweden)

    Ana Sanchez-Sanchez

    2015-01-01

    Full Text Available Single-chain technology (SCT allows the transformation of individual polymer chains to folded/collapsed unimolecular soft nanoparticles. In this work we contribute to the enlargement of the SCT toolbox by demonstrating the efficient synthesis of single-chain polymer nanoparticles (SCNPs via intrachain amide formation. In particular, we exploit cross-linking between active methylene groups and isocyanate moieties as powerful “click” chemistry driving force for SCNP construction. By employing poly(methyl methacrylate- (PMMA- based copolymers bearing β-ketoester units distributed randomly along the copolymer chains and bifunctional isocyanate cross-linkers, SCNPs were successfully synthesized at r.t. under appropriate reaction conditions. Characterization of the resulting SCNPs was carried out by means of a combination of techniques including size exclusion chromatography (SEC, infrared (IR spectroscopy, proton nuclear magnetic resonance (1H NMR spectroscopy, dynamic light scattering (DLS, and elemental analysis (EA.

  11. Pressure-sensing properties of single-walled carbon nanotubes covered with a corona-poled piezoelectric polymer

    Energy Technology Data Exchange (ETDEWEB)

    Ikawa, Takeshi; Tabata, Hiroshi, E-mail: tabata@eei.eng.osaka-u.ac.jp; Yoshizawa, Takeshi; Utaka, Ken; Kubo, Osamu; Katayama, Mitsuhiro [Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2016-07-18

    Single-walled carbon nanotubes (SWNTs) have been studied extensively as sensing elements for chemical and biochemical sensors because of their excellent electrical properties, their ultrahigh ratio of surface area to volume, and the consequent extremely high sensitivity of their surface to the surrounding environment. The extremely high sensitivity indicates that SWNTs can operate as excellent transducers when combined with piezoelectric materials. In this paper, we present a touch sensor based on SWNT thin-film transistors (SWNT-TFTs) covered with a thin film of the piezoelectric polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). Devices were fabricated by spin-coating a P(VDF-TrFE) layer on an SWNT-TFT, which was followed by in situ corona poling to polarize the P(VDF-TrFE) layer. We studied the effect of the corona polarity on the device characteristics and revealed that poling with a negative corona discharge induced a large amount of hole doping in the SWNTs and improved the touch-sensing performance of the devices, while a positive discharge had a negligible effect. The poled devices exhibited regular, stable, and positive drain current modulation in response to intermittent pressing, and the response was proportional to the magnitude of the applied pressure, suggesting that it was caused by the piezoelectric effect of the polarized P(VDF-TrFE) layer. Furthermore, we also fabricated a device using horizontally aligned SWNTs with a lower SWNT density as an alternative transducer to an SWNT thin film, which demonstrated sensitivity as high as 70%/MPa.

  12. Experimental studies of the dynamic mechanical response of a single polymer chain

    DEFF Research Database (Denmark)

    Thormann, Esben; Evans, Drew R.; Craig, Vincent S. J.

    2006-01-01

    The high-frequency and low-amplitude dynamic mechanical response from a single poly(vinyl alcohol) chain was investigated. Modification of a commercial atomic force microscope enabled high-frequency and low-amplitude periodic deformations of polymer chains during extension to be performed...... mechanical response from poly(vinyl alcohol) does not differ from its static response. This result is not unexpected as poly(vinyl alcohol) is a highly flexible polymer with intramolecular relaxation processes taking place on a short time scale. The choice of a polymer with a fast relaxation allows its...... static properties to be recovered from the dynamic measurements and enables the method suggested in this paper for decoupling the polymer response from the hydrodynamic response to be validated....

  13. Sm-doped CeO{sub 2} single buffer layer for YBCO coated conductors by polymer assisted chemical solution deposition (PACSD) method

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.; Pu, M.H.; Sun, R.P.; Wang, W.T.; Wu, W.; Zhang, X.; Yang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)], E-mail: yzhao@home.swjtu.edu.cn

    2008-10-20

    An over 150 nm thick Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9-x} (SCO) single buffer layer has been deposited on bi-axially textured NiW (2 0 0) alloy substrate. Highly in-plane and out-of-plane oriented, dense, smooth and crack free SCO single layer has been obtained via a polymer-assisted chemical solution deposition (PACSD) approach. YBCO thin film has been deposited equally via a PACSD route on the SCO-buffered NiW, the as grown YBCO yielding a sharp transition at T{sub c0} = 87 K as well as J{sub c}(0 T, 77 K) {approx} 1 MA/cm{sup 2}. These results indicates that RE (lanthanides other than Ce) doping may be an effective approach to improve the critical thickness of solution derived CeO{sub 2} film, which renders it a promising candidate as single buffer layer for YBCO coated conductors.

  14. Efficient protein-repelling thin films regulated by chain mobility of low-Tg polymers with increased stability via crosslinking

    Science.gov (United States)

    Zhang, Jinghui; Huang, Zhiwei; Liu, Dan

    2017-12-01

    Polymer thin films are generally employed as coatings on implants to prevent protein adsorption. Polymer chain mobility and surface softness have been found to contribute to the protein resistance, but also bring film instability in a liquid protein medium. We investigated the protein resistance ability of three low-Tg polymers, including hydrophobic polymers polyisoprene (PI), poly(n-butyl methacrylate) (PnBMA) and hydrophilic polyethylene oxide (PEO), by overcoming the instability issue with crosslinking. We found that the Tgs of PI and PEO can be increased to around 0 °C after crosslinking. The remained strong chain mobility of both films can still resist protein adsorption regardless the hydrophobicity, yet greatly increases the film stability under an aqueous circumstance. The PnBMA film increased its Tg to around room temperature after crosslinking, which deteriorated the protein-resistance ability having the surface covered by BSA molecules. Our results support that the chain mobility of a polymer film plays an important role in resisting protein adsorption due to the increased entropy associated with more mobile polymer chains. By tune the degree of crosslinking, the stability of polymer in aqueous environment can be increased while the protein resistant ability can be remained. Our results provide a new strategy to design polymer materials for effective antifouling.

  15. Metal-free, single-polymer device exhibits resistive memory effect

    KAUST Repository

    Bhansali, Unnat Sampatraj; Khan, Yasser; Cha, Dong Kyu; Almadhoun, Mahmoud N.; Li, Ruipeng; Chen, Long; Amassian, Aram; Odeh, Ihab N.; Alshareef, Husam N.

    2013-01-01

    All-polymer, write-once-read-many times resistive memory devices have been fabricated on flexible substrates using a single polymer, poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Spin-cast or inkjet-printed films of solvent-modified PEDOT:PSS are used as electrodes, while the unmodified or as-is PEDOT:PSS is used as the semiconducting active layer. The all-polymer devices exhibit an irreversible but stable transition from a low resistance state (ON) to a high resistance state (OFF) at low voltages caused by an electric-field-induced morphological rearrangement of PEDOT and PSS at the electrode interface. However, in the metal-PEDOT:PSS-metal devices, we have shown a metal filament formation switching the device from an initial high resistance state (OFF) to the low resistance state (ON). The all-PEDOT:PSS memory device has low write voltages (<3 V), high ON/OFF ratio (>10 3), good retention characteristics (>10 000 s), and stability in ambient storage (>3 months). © 2013 American Chemical Society.

  16. Metal-free, single-polymer device exhibits resistive memory effect

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-12-23

    All-polymer, write-once-read-many times resistive memory devices have been fabricated on flexible substrates using a single polymer, poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Spin-cast or inkjet-printed films of solvent-modified PEDOT:PSS are used as electrodes, while the unmodified or as-is PEDOT:PSS is used as the semiconducting active layer. The all-polymer devices exhibit an irreversible but stable transition from a low resistance state (ON) to a high resistance state (OFF) at low voltages caused by an electric-field-induced morphological rearrangement of PEDOT and PSS at the electrode interface. However, in the metal-PEDOT:PSS-metal devices, we have shown a metal filament formation switching the device from an initial high resistance state (OFF) to the low resistance state (ON). The all-PEDOT:PSS memory device has low write voltages (<3 V), high ON/OFF ratio (>10 3), good retention characteristics (>10 000 s), and stability in ambient storage (>3 months). © 2013 American Chemical Society.

  17. Polymer-ZnO nanocomposites foils and thin films for UV protection

    International Nuclear Information System (INIS)

    Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya; Yunus, Wan Mahmood Mat

    2014-01-01

    The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images

  18. Polymer-ZnO nanocomposites foils and thin films for UV protection

    Energy Technology Data Exchange (ETDEWEB)

    Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM, Serdang (Malaysia)

    2014-09-03

    The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.

  19. [Synthesis and Characterization of a Sugar Based Electrolyte for Thin-film Polymer Batteries

    Science.gov (United States)

    1998-01-01

    The work performed during the current renewal period, March 1,1998 focused primarily on the synthesis and characterization of a sugar based electrolyte for thin-film polymer batteries. The initial phase of the project involved developing a suitable sugar to use as the monomer in the polymeric electrolyte synthesis. The monomer has been synthesized and characterized completely. Overall the yield of this material is high and it can be produced in relatively large quantity easily and in high purity. The scheme used for the preparation of the monomer is outlined along with pertinent yields.

  20. Junction Propagation in Organometal Halide Perovskite-Polymer Composite Thin Films.

    Science.gov (United States)

    Shan, Xin; Li, Junqiang; Chen, Mingming; Geske, Thomas; Bade, Sri Ganesh R; Yu, Zhibin

    2017-06-01

    With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p-i-n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr 3 )/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation.

  1. Alkylated indacenodithieno[3,2-b]thiophene-based all donor ladder-type conjugated polymers for organic thin film transistors

    KAUST Repository

    Lu, Rimei

    2018-01-29

    We report the synthesis of a series of indacenodithieno[3,2-b]thiophene (IDTT) based conjugated polymers by copolymerization with three different electron rich co-monomers [thiophene (T), thieno[3,2-b]thiophene (TT) and dithieno[3,2-b:2\\',3\\'-d]thiophene (DTT)] under Stille coupling conditions. The resulting all-donor polymers show very good solubility in common solvents and exhibit similar optical, thermal and electronic properties. However, the performance of these semiconductors in thin film transistor devices varied and was highly dependent on the nature of the co-monomer. All polymers exhibited unipolar p-type charge transport behaviour, with the mobility values following the trend of IDTT-TT>IDTT-DTT>IDTT-T. The peak saturation mobility value of IDTT-TT was extracted to be 1.1 cm2V-1s-1, amongst the highest mobility for all-donor conjugated polymers reported to date.

  2. Tracing Single Electrons in a Disordered Polymer Film at Room Temperature.

    Science.gov (United States)

    Wilma, Kevin; Issac, Abey; Chen, Zhijian; Würthner, Frank; Hildner, Richard; Köhler, Jürgen

    2016-04-21

    The transport of charges lies at the heart of essentially all modern (opto-) electronic devices. Although inorganic semiconductors built the basis for current technologies, organic materials have become increasingly important in recent years. However, organic matter is often highly disordered, which directly impacts the charge carrier dynamics. To understand and optimize device performance, detailed knowledge of the transport mechanisms of charge carriers in disordered matter is therefore of crucial importance. Here we report on the observation of the motion of single electrons within a disordered polymer film at room temperature, using single organic chromophores as probe molecules. The migration of a single electron gives rise to a varying electric field in its vicinity, which is registered via a shift of the emission spectra (Stark shift) of a chromophore. The spectral shifts allow us to determine the electron mobility and reveal for each nanoenvironment a distinct number of different possible electron-transfer pathways within the rugged energy landscape of the disordered polymer matrix.

  3. Photoluminescence Spectroscopy of Rhodamine 800 Aqueous Solution and Dye-Doped Polymer Thin-Film: Concentration and Solvent Effects

    Science.gov (United States)

    Le, Khai Q.; Dang, Ngo Hai

    2018-05-01

    This paper investigates solvent and concentration effects on photoluminescence (PL) or fluorescence properties of Rhodamine 800 (Rho800) dyes formed in aqueous solution and polymer thin-film. Various commonly used organic solvents including ethanol, methanol and cyclopentanol were studied at a constant dye concentration. There were small changes in the PL spectra for the different solvents in terms of PL intensity and peak wavelength. The highest PL intensity was observed for cyclopentanol and the lowest for ethanol. The longest peak wavelength was found in cyclopentanol (716 nm) and the shortest in methanol (708 nm). Dissolving the dye powder in the methanol solvent and varying the dye concentration in aqueous solution from the high concentrated solution to highly dilute states, the wavelength tunability was observed between about 700 nm in the dilute state and 730 nm at high concentration. Such a large shift may be attributed to the formation of dye aggregates. Rho800 dye-doped polyvinyl alcohol (PVA) polymer thin-film was further investigated. The PL intensity of the dye in the form of thin-film is lower than that of the aqueous solution form whereas the peak wavelength is redshifted due to the presence of PVA. This paper, to our best knowledge, reports the first study of spectroscopic properties of Rho800 dyes in various forms and provides useful guidelines for production of controllable organic luminescence sources.

  4. Crack density and electrical resistance in indium-tin-oxide/polymer thin films under cyclic loading

    KAUST Repository

    Mora Cordova, Angel

    2014-11-01

    Here, we propose a damage model that describes the degradation of the material properties of indium-tin-oxide (ITO) thin films deposited on polymer substrates under cyclic loading. We base this model on our earlier tensile test model and show that the new model is suitable for cyclic loading. After calibration with experimental data, we are able to capture the stress-strain behavior and changes in electrical resistance of ITO thin films. We are also able to predict the crack density using calibrations from our previous model. Finally, we demonstrate the capabilities of our model based on simulations using material properties reported in the literature. Our model is implemented in the commercially available finite element software ABAQUS using a user subroutine UMAT.[Figure not available: see fulltext.].

  5. Single-Molecule Imaging Reveals Topology Dependent Mutual Relaxation of Polymer Chains

    KAUST Repository

    Abadi, Maram; Serag, Maged F.; Habuchi, Satoshi

    2015-01-01

    The motion and relaxation of linear and cyclic polymers under entangled conditions are investigated by means of a newly developed single-molecule tracking technique, cumulative-area (CA) tracking. CA tracking enables simultaneous quantitative characterization of the diffusion mode, diffusion rate, and relaxation time that have been impossible with a widely used conventional single-molecule localization and tracking method, by analyzing cumulative areas occupied by the moving molecule. Using the novel approach, we investigate the motion and relaxation of entangled cyclic polymers, which have been an important but poorly understood question. Fluorescently labeled 42 kbp linear or cyclic tracer dsDNAs in concentrated solutions of unlabeled linear or cyclic DNAs are used as model systems. We show that CA tracking can explicitly distinguish topology-dependent diffusion mode, rate, and relaxation time, demonstrating that the method provides an invaluable tool for characterizing topological interaction between the entangled chains. We further demonstrate that the current models proposed for the entanglement between cyclic polymers which are based on cyclic chains moving through an array of fixed obstacles cannot correctly describe the motion of the cyclic chain under the entangled conditions. Our results rather suggest the mutual relaxation of the cyclic chains, which underscore the necessity of developing a new model to describe the motion of cyclic polymer under the entangled conditions based on the mutual interaction of the chains.

  6. Single-Molecule Imaging Reveals Topology Dependent Mutual Relaxation of Polymer Chains

    KAUST Repository

    Abadi, Maram

    2015-08-24

    The motion and relaxation of linear and cyclic polymers under entangled conditions are investigated by means of a newly developed single-molecule tracking technique, cumulative-area (CA) tracking. CA tracking enables simultaneous quantitative characterization of the diffusion mode, diffusion rate, and relaxation time that have been impossible with a widely used conventional single-molecule localization and tracking method, by analyzing cumulative areas occupied by the moving molecule. Using the novel approach, we investigate the motion and relaxation of entangled cyclic polymers, which have been an important but poorly understood question. Fluorescently labeled 42 kbp linear or cyclic tracer dsDNAs in concentrated solutions of unlabeled linear or cyclic DNAs are used as model systems. We show that CA tracking can explicitly distinguish topology-dependent diffusion mode, rate, and relaxation time, demonstrating that the method provides an invaluable tool for characterizing topological interaction between the entangled chains. We further demonstrate that the current models proposed for the entanglement between cyclic polymers which are based on cyclic chains moving through an array of fixed obstacles cannot correctly describe the motion of the cyclic chain under the entangled conditions. Our results rather suggest the mutual relaxation of the cyclic chains, which underscore the necessity of developing a new model to describe the motion of cyclic polymer under the entangled conditions based on the mutual interaction of the chains.

  7. Improved polymer thin-film wetting behavior through nanoparticle segregation to interfaces

    International Nuclear Information System (INIS)

    Krishnan, R S; Mackay, M E; Duxbury, P M; Hawker, C J; Asokan, Suba; Wong, Michael S; Goyette, Rick; Thiyagarajan, P

    2007-01-01

    We report a systematic study of improved wetting behavior for thin polymer films containing nanoparticles, as a function of nanoparticle size and concentration, the energy of the substrate and the dielectric properties of the nanoparticles. An enthalpy matched system consisting of polystyrene nanoparticles in linear polystyrene is used to show that nanoparticles are uniformly distributed in the film after spin coating and drying. However, on annealing the film above its bulk glass transition temperature these nanoparticles segregate strongly to the solid substrate. We find that for a wide range of film thicknesses and nanoparticle sizes, a substrate coverage of nanoparticles of approximately a monolayer is required for dewetting inhibition. Cadmium selenide quantum dots also inhibit dewetting of polystyrene thin films, again when a monolayer is present. Moreover, TEM microscopy images indicate that CdSe quantum dots segregate primarily to the air interface. Theoretical interpretation of these phenomena suggests that gain of linear chain configurational entropy promotes segregation of nanoparticles to the solid substrate, as occurs for polystyrene nanoparticles; however, for CdSe nanoparticles this is offset by surface energy or enthalpic terms which promote segregation of the nanoparticles to the air interface

  8. Energy harvesting using ionic electro-active polymer thin films with Ag-based electrodes

    International Nuclear Information System (INIS)

    Anand, S V; Arvind, K; Bharath, P; Roy Mahapatra, D

    2010-01-01

    In this paper we employ the phenomenon of bending deformation induced transport of cations via the polymer chains in the thickness direction of an electro-active polymer (EAP)–metal composite thin film for mechanical energy harvesting. While EAPs have been applied in the past in actuators and artificial muscles, promising applications of such materials in hydrodynamic and vibratory energy harvesting are reported in this paper. For this, functionalization of EAPs with metal electrodes is the key factor in improving the energy harvesting efficiency. Unlike Pt-based electrodes, Ag-based electrodes have been deposited on an EAP membrane made of Nafion. The developed ionic metal polymer composite (IPMC) membrane is subjected to a dynamic bending load, hydrodynamically, and evaluated for the voltage generated against an external electrical load. An increase of a few orders of magnitude has been observed in the harvested energy density and power density in air, deionized water and in electrolyte solutions with varying concentrations of sodium chloride (NaCl) as compared to Pt-based IPMC performances reported in the published literature. This will have potential applications in hydrodynamic and residual environmental energy harvesting to power sensors and actuators based on micro-and nano-electro-mechanical systems (MEMS and NEMS) for biomedical, aerospace and oceanic applications

  9. Ultrathin Polymer Films, Patterned Arrays, and Microwells

    Science.gov (United States)

    Yan, Mingdi

    2002-05-01

    The ability to control and tailor the surface and interface properties of materials is important in microelectronics, cell growth control, and lab-on-a-chip devices. Modification of material surfaces with ultrathin polymer films is attractive due to the availability of a variety of polymers either commercially or by synthesis. We have developed two approaches to the attachment of ultrathin polymer films on solid substrates. In the first method, a silane-functionalized perfluorophenyl azide (PFPA-silane) was synthesized and used to covalently immobilize polymer thin films on silicon wafers. Silanization of the wafer surface with the PFPA-silane introduced a monolayer of azido groups which in turn covalently attached the polymer film by way of photochemically initiated insertion reactions. The thickness of the film could be adjusted by the type and the molecular weight of the polymer. The method is versatile due to the general C-H and/or N-H insertion reactions of crosslinker; and therefore, no specific reactive functional groups on the polymers are required. Using this method, a new type of microwell array was fabricated from covalently immobilized polymer thin films on flat substrates. The arrays were characterized with AFM, XPS, and TOF-SIMS. The second method describes the attachment of polymer thin films on solid substrates via UV irradiation. The procedure consisted of spin-coating a polymer film and irradiating the film with UV light. Following solvent extraction, a thin film remained. The thickness of the film, from a few to over a hundred nanometers, was controlled by varying solution concentration and the molecular weight of the polymer.

  10. Thin film microelectrodes for electrochemical detection of neurotransmitters

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard

    An important signaling process in the nervous system is the release of chemical messengers called neurotransmitters from neurons. In this thesis alternative thin film electrode materials for applications targeting electrochemical detection of neurotransmitters in chip devices were evaluated...... and conductive polymer microelectrodes made of Pedot:Pss were also fabricated and used successfully to measure transmitter release from cells. The use of different thin film electrodes for low-noise amperometric measurements of single events of transmitter release from neuronal cells was studied....... For this application a very low current noise is needed together with a large temporal resolution. It was shown, that resistive and capacitive properties of thin film electrode materials are determining their usefulness in low-noise amperometric measurements. An analytical expression for the noise was derived...

  11. Thinning Approximation for Two-Dimensional Scattering Patterns from Coarse-Grained Polymer Melts under Shear Flow

    Science.gov (United States)

    Hagita, Katsumi; Murashima, Takahiro; Takano, Hiroshi; Kawakatsu, Toshihiro

    2017-12-01

    We proposed a thinning approximation (TA) for estimation of the two-dimensional (2D) wide-angle scattering patterns from Kremer-Grest polymer melts under shear. In the TA, extra particles are inserted at the middle of bonds for fine-graining of the coarse-grained polymers. For the case without the TA, spots corresponding to the orientation of bonds at a high shear rate are difficult to observe because the bond length of successive particles is comparable to the distance between neighboring particles. With the insertion of the extra particles, a ring pattern originating from the neighboring particles can be moved to a wide-angle region. Thus, we can observe the spots at high shear rates. We also examined the relationship between 2D scattering patterns and the Weissenberg number, which is defined as the product of the shear rate and the longest relaxation time. It is confirmed that the relationship for coarse-grained polymers with the TA is consistent with that of the all-atomistic model of polyethylene.

  12. Mass Transfer in Amperometric Biosensors Based on Nanocomposite Thin Films of Redox Polymers and Oxidoreductases

    Directory of Open Access Journals (Sweden)

    Aleksandr L. Simonian

    2002-03-01

    Full Text Available Mass transfer in nanocomposite hydrogel thin films consisting of alternating layers of an organometallic redox polymer (RP and oxidoreductase enzymes was investigated. Multilayer nanostructures were fabricated on gold surfaces by the deposition of an anionic self-assembled monolayer of 11-mercaptoundecanoic acid, followed by the electrostatic binding of a cationic redox polymer, poly[vinylpyridine Os(bis-bipyridine2Clco-allylamine], and an anionic oxidoreductase. Surface plasmon resonance spectroscopy, Fourier transform infrared external reflection spectroscopy (FTIR-ERS, ellipsometry and electrochemistry were employed to characterize the assembly of these nanocomposite films. Simultaneous SPR/electrochemistry enabled real time observation of the assembly of sensing components, changes in film structure with electrode potential, and the immediate, in situ electrochemical verification of substrate-dependent current upon the addition of enzyme to the multilayer structure. SPR and FTIR-ERS studies also showed no desorption of polymer or enzyme from the nanocomposite structure when stored in aqueous environment occurred over the period of three weeks, suggesting that decreasing in substrate sensitivity were due to loss of enzymatic activity rather than loss of film compounds from the nanostructure.

  13. Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes

    International Nuclear Information System (INIS)

    Chen Wei; Tao Xiaoming

    2006-01-01

    We reported a simple method to fabricate polymer nanocomposites with single-walled carbon nanotubes (SWNTs) having exceptional alignment and improved mechanical properties. The composite films were fabricated by casting a suspension of single walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. The orientation as well as dispersion of nanotubes was determined by scanning electron microscopy, transmission electron microscopy and polarized Raman spectroscopy. The macroscopic alignment probably results from solvent-polymer interaction induced orientation of soft segment chain during swelling and moisture curing. The tensile behavior of the aligned nanotube composite film was also studied. At a 0.5 wt.% nanotube loading, a 1.9-fold increase in Young's modulus was achieved

  14. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm 2/Vs

    KAUST Repository

    Smith, Jeremy N.; Zhang, Weimin; Sougrat, Rachid; Zhao, Kui; Li, Ruipeng; Cha, Dong Kyu; Amassian, Aram; Heeney, Martin J.; McCulloch, Iain A.; Anthopoulos, Thomas D.

    2012-01-01

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm 2/Vs, current on/off ratio ≥10 6 and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm 2/Vs

    KAUST Repository

    Smith, Jeremy N.

    2012-04-10

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm 2/Vs, current on/off ratio ≥10 6 and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Laser patterning of transparent polymers assisted by plasmon excitation.

    Science.gov (United States)

    Elashnikov, R; Trelin, A; Otta, J; Fitl, P; Mares, D; Jerabek, V; Svorcik, V; Lyutakov, O

    2018-06-13

    Plasmon-assisted lithography of thin transparent polymer films, based on polymer mass-redistribution under plasmon excitation, is presented. The plasmon-supported structures were prepared by thermal annealing of thin Ag films sputtered on glass or glass/graphene substrates. Thin films of polymethylmethacrylate, polystyrene and polylactic acid were then spin-coated on the created plasmon-supported structures. Subsequent laser beam writing, at the wavelength corresponding to the position of plasmon absorption, leads to mass redistribution and patterning of the thin polymer films. The prepared structures were characterized using UV-Vis spectroscopy and confocal and AFM microscopy. The shape of the prepared structures was found to be strongly dependent on the substrate type. The mechanism leading to polymer patterning was examined and attributed to the plasmon-heating. The proposed method makes it possible to create different patterns in polymer films without the need for wet technological stages, powerful light sources or a change in the polymer optical properties.

  17. Constructing anisotropic single-Dirac-cones in Bi(1-x)Sb(x) thin films.

    Science.gov (United States)

    Tang, Shuang; Dresselhaus, Mildred S

    2012-04-11

    The electronic band structures of Bi(1-x)Sb(x) thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness, and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi(1-x)Sb(x) thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band gap, which can be used in a general two-dimensional system that has a nonparabolic dispersion relation as in the Bi(1-x)Sb(x) thin film system. © 2012 American Chemical Society

  18. Characterization of Thin Film Polymers Through Dynamic Mechanical Analysis and Permeation

    Science.gov (United States)

    Herring, Helen

    2003-01-01

    Thin polymer films are being considered, as candidate materials to augment the permeation resistance of cryogenic hydrogen fuel tanks such as would be required for future reusable launch vehicles. To evaluate performance of candidate films after environmental exposure, an experimental study was performed to measure the thermal/mechanical and permeation performance of six, commercial-grade materials. Dynamic storage modulus, as measured by Dynamic Mechanical Analysis, was found over a range of temperatures. Permeability, as measured by helium gas diffusion, was found at room temperature. Test data was correlated with respect to film type and pre-test exposure to moisture, elevated temperature, and cryogenic temperature. Results indicated that the six films were comparable in performance and their resistance to environmental degradation.

  19. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo

    2010-09-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform thickness (<100 nm) is crucial. By using a tailor-made polymer and by controlling the nanofabrication conditions, we developed and manufactured defect-free ultra-thin film membranes with unmatched carbon dioxide permeances, i.e. >5 m3 (STP) m-2 h -1 bar-1. The permeances are extremely high, because the membranes are made from a CO2 philic polymer material and they are only a few tens of nanometers thin. Thus, these thin film membranes have potential application in the treatment of large gas streams under low pressure like, e.g., carbon dioxide separation from flue gas. © 2010 IOP Publishing Ltd.

  20. Low-loss single mode light waveguides in polymer

    Science.gov (United States)

    Sieber, Heinrich; Boehm, Hans-Jürgen; Hollenbach, Uwe; Mohr, Jürgen; Ostrzinski, Ute; Pfeiffer, Karl; Szczurowski, Marcin; Urbanczyk, Waclaw

    2012-06-01

    We report on the development of a UV-lithography manufacturing process for low loss single mode light waveguides in a novel polymer and the characterization of the fabricated components in a broad wavelength range from 808 nm to 1550 nm. The main focus of this work lies in providing a quick and cost efficient production technique for single mode waveguides and low loss integrated optical circuits. To achieve this goal we chose a novel photo-structurable polymer host-guest-system consisting of SU8 and a low refractive dopant monomer. Near and far-field measurements at different wavelengths show that the mode propagating within a well designed integrated waveguide structure and the mode of a standard fiber can exhibit a mode overlap value of approximately 1 and suffer only very low coupling losses. We demonstrate excess loss of 0.14 dB/cm for 808 nm, 0.33 dB/cm for 1310 nm and 2.86 dB/cm for 1550 nm. Typical insertion loss values of straight waveguides with a length of 36 mm are 0.9 dB for 808 nm, 1.5 dB for 1310 nm and 10.4 dB for 1550 nm. Polarization dependent loss was found to be less than 0.2 dB on sets of test structures of 36 mm length. We measured material attenuation in the novel polymer material before cross-linking of approximately 0.04 dB/cm for 808 nm and around 0.20 dB/cm for 1310 nm respectively. The presented production technique is suitable to provide low loss and low cost integrated optical circuits for sensor and communication applications in a broad wavelength range.

  1. Nanowire decorated, ultra-thin, single crystalline silicon for photovoltaic devices.

    Science.gov (United States)

    Aurang, Pantea; Turan, Rasit; Unalan, Husnu Emrah

    2017-10-06

    Reducing silicon (Si) wafer thickness in the photovoltaic industry has always been demanded for lowering the overall cost. Further benefits such as short collection lengths and improved open circuit voltages can also be achieved by Si thickness reduction. However, the problem with thin films is poor light absorption. One way to decrease optical losses in photovoltaic devices is to minimize the front side reflection. This approach can be applied to front contacted ultra-thin crystalline Si solar cells to increase the light absorption. In this work, homojunction solar cells were fabricated using ultra-thin and flexible single crystal Si wafers. A metal assisted chemical etching method was used for the nanowire (NW) texturization of ultra-thin Si wafers to compensate weak light absorption. A relative improvement of 56% in the reflectivity was observed for ultra-thin Si wafers with the thickness of 20 ± 0.2 μm upon NW texturization. NW length and top contact optimization resulted in a relative enhancement of 23% ± 5% in photovoltaic conversion efficiency.

  2. Self-Assembled CNT-Polymer Hybrids in Single-Walled Carbon Nanotubes Dispersed Aqueous Triblock Copolymer Solutions

    Science.gov (United States)

    Vijayaraghavan, D.; Manjunatha, A. S.; Poojitha, C. G.

    2018-04-01

    We have carried out scanning electron microscopy (SEM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), electrical conductivity, and 1H NMR studies as a function of temperature on single-walled carbon nanotubes (SWCNTs) dispersed aqueous triblock copolymer (P123) solutions. The single-walled carbon nanotubes in this system aggregate to form bundles, and the bundles aggregate to form net-like structures. Depending on the temperature and phases of the polymer, this system exhibits three different self-assembled CNT-polymer hybrids. We find CNT-unimer hybrid at low temperatures, CNT-micelle hybrid at intermediate temperatures wherein the polymer micelles are adsorbed in the pores of the CNT nets, and another type of CNT-micelle hybrid at high temperatures wherein the polymer micelles are adsorbed on the surface of the CNT bundles. Our DSC thermogram showed two peaks related to these structural changes in the CNT-polymer hybrids. Temperature dependence of the 1H NMR chemical shifts of the molecular groups of the polymer and the AC electrical conductivity of the composite also showed discontinuous changes at the temperatures at which the CNT-polymer hybrid's structural changes are seen. Interestingly, for a higher CNT concentration (0.5 wt.%) in the system, the aggregated polymer micelles adsorbed on the CNTs exhibit cone-like and cube-like morphologies at the intermediate and at high temperatures respectively.

  3. Nanoparticles Stabilize Thin Polymer Films: A Fundamental Study to Understand the Phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Michael E. Mackay

    2009-03-04

    A new understanding of thermodynamics at the nanoscale resulted in a recently discovered first order phase transition that nanoparticles in a polymer film will all segregate to the supporting substrate. This is an unusual phase transition that was predicted using a modeling technique developed at Sandia National Laboratories and required the equivalent of many computational years on one computer. This project is a collaboration between Prof. Michael Mackay's group and Dr. Amalie Frischknecht (Sandia National Laboratories) where experimental observation and theoretical rationalization and prediction are brought together. Other discoveries were that this phase transition could be avoided by changing the nanoparticle properties yielding control of the assembly process at the nanoscale. In fact, the nanoparticles could be made to assemble to the supporting substrate, to the air interface or not assemble at all within a thin polymer film of order 100 nm in thickness. However, when the assembly process is present it is so robust that it is possible to make rough liquid films at the nanoscale due to nanoparticles assembling around three-dimensional objects. From this knowledge we are able to design and manufacture new coatings with particular emphasis on polymer-based solar cells. Careful control of the morphology at the nanoscale is expected to provide more efficient devices since the physics of these systems is dictated at this length scale and assembly of nanoparticles to various interfaces is critical to operation.

  4. High-Performance Single-Crystalline Perovskite Thin-Film Photodetector

    KAUST Repository

    Yang, Zhenqian

    2018-01-10

    The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light-emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin-film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC-TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain-bandwidth product, and a 100-photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness-optimized SC-TF with much higher mobility and longer recombination time. The results indicate that high-performance perovskite devices based on SC-TF may become competitive in modern optoelectronics.

  5. Confinement Effects on Host Chain Dynamics in Polymer Nanocomposite Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle J. [Department; Glynos, Emmanouil [Department; Maroulas, Serafeim-Dionysios [Department; Narayanan, Suresh [Advanced; Sakellariou, Georgios [Department; Green, Peter F. [Department; National

    2017-09-06

    Incorporating nanoparticles (NPs) within a polymer host to create polymer nanocomposites (PNCs) while having the effect of increasing the functionality (e.g.: sensing, energy conversion) of these materials, introduces additional complications with regard to the processing-morphology-function behavior. A primary challenge is to understand and control the viscosity of a PNC with decreasing film thickness confinement for nanoscale applications. Using a combination of X-ray photon correlation spectroscopy (XPCS) and X-ray standing wave based resonance enhanced XPCS to study the dynamics of neat poly-2-vinyl pyridine (P2VP) chains and the nanoparticle dynamics, respectively, we identified a new mechanism that dictates the viscosity of PNC films in the nanoscale regime. We show that while the viscosities of neat P2VP films as thin as 50 nm remained the same as the bulk, PNC films containing P2VP brush-coated gold NPs, spaced 50 nm apart, exhibited unprecedented increases in viscosities of over an order of magnitude. For thicker films or more widely separated NPs, the chain dynamics and viscosities were equal to the bulk values. These results -NP proximities and suppression of their dynamics -suggest a new mechanism by which the viscosities of polymeric liquids could be controlled for 2D and 3D nanoscale applications.

  6. Transparent conductive ZnO layers on polymer substrates: Thin film deposition and application in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dosmailov, M. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Leonat, L.N. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Patek, J. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Roth, D.; Bauer, P. [Institute of Experimental Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Scharber, M.C.; Sariciftci, N.S. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2015-09-30

    Aluminum doped ZnO (AZO) and pure ZnO thin films are grown on polymer substrates by pulsed-laser deposition and the optical, electrical, and structural film properties are investigated. Laser fluence, substrate temperature, and oxygen pressure are varied to obtain transparent, conductive, and stoichiometric AZO layers on polyethylene terephthalate (PET) that are free of cracks. At low fluence (1 J/cm{sup 2}) and low pressure (10{sup −3} mbar), AZO/PET samples of high optical transmission in the visible range, low electrical sheet resistance, and high figure of merit (FOM) are produced. AZO films on fluorinated ethylene propylene have low FOM. The AZO films on PET substrates are used as electron transport layer in inverted organic solar cell devices employing P3HT:PCBM as photovoltaic polymer-fullerene bulk heterojunction. - Highlights: • Aluminum doped and pure ZnO thin films are grown on polyethylene terephthalate. • Growth parameters laser fluence, temperature, and gas pressure are optimized. • AZO films on PET have high optical transmission and electrical conductance (FOM). • Organic solar cells on PET using AZO as electron transport layer are made. • Power conversion efficiency of these OSC devices is measured.

  7. Hierarchical Fiber Structures Made by Electrospinning Polymers

    Science.gov (United States)

    Reneker, Darrell H.

    2009-03-01

    A filter for water purification that is very thin, with small interstices and high surface area per unit mass, can be made with nanofibers. The mechanical strength of a very thin sheet of nanofibers is not great enough to withstand the pressure drop of the fluid flowing through. If the sheet of nanofibers is made thicker, the strength will increase, but the flow will be reduced to an impractical level. An optimized filter can be made with nanometer scale structures supported on micron scale structures, which are in turn supported on millimeter scale structures. This leads to a durable hierarchical structure to optimize the filtration efficiency with a minimum amount of material. Buckling coils,ootnotetextTao Han, Darrell H Reneker, Alexander L. Yarin, Polymer, Volume 48, issue 20 (September 21, 2007), p. 6064-6076. electrical bending coilsootnotetextDarrell H. Reneker and Alexander L. Yarin, Polymer, Volume 49, Issue 10 (2008) Pages 2387-2425, DOI:10.1016/j.polymer.2008.02.002. Feature Article. and pendulum coilsootnotetextT. Han, D.H. Reneker, A.L. Yarin, Polymer, Volume 49, (2008) Pages 2160-2169, doi:10.1016/jpolymer.2008.01.0487878. spanning dimensions from a few microns to a few centimeters can be collected from a single jet by controlling the position and motion of a collector. Attractive routes to the design and construction of hierarchical structures for filtration are based on nanofibers supported on small coils that are in turn supported on larger coils, which are supported on even larger overlapping coils. ``Such top-down'' hierarchical structures are easy to make by electrospinning. In one example, a thin hierarchical structure was made, with a high surface area and small interstices, having an open area of over 50%, with the thinnest fibers supported at least every 15 microns.

  8. Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes/polymer composite thin film.

    Science.gov (United States)

    Rajanna, Pramod Mulbagal; Gilshteyn, Evgenia; Yagafarov, Timur; Alekseeva, Alena; Anisimov, Anton; Sergeev, Oleg; Neumueller, Alex; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert

    2018-01-09

    We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and a thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high quality SWCNTs with an enhanced conductivity by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with different SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit Jsc, open-circuit Voc, and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and efficiency of 3.4% under simulated one-sun AM 1.5G direct illumination. © 2018 IOP Publishing Ltd.

  9. Laboratory Analysis of Polymer Thin Films for Planetary Balloons and Gossamer Structures

    Science.gov (United States)

    Sterling, Jerry; Fairbrother, Debora A.

    2004-01-01

    Commercially available polymer thin fdms with thickness of 15 microns or less were evaluated for potential application as the gas envelope material of balloons and other inflated vehicles. Films on this thickness scale are of interest for Earth and Mars ballooning as well as many gossamer space structures. Due to the uniqueness of these missions relative to typical uses of these materials, application-specific materials properties measurements were made. We evaluated numerous polymer chemistries, plus a few variations within one chemistry. The data show that there are often trade-offs among the different materials, such as with polyesters and polyimides having greater stiffness (modulus) but lower tear propagation resistance than polyethylene. Sections of polyethylene films can be joined by heat sealing, while adhesives and their accompanying mass penalty must be used with polyesters and polyimides. When the analysis temperature is reduced to 190 K, polyethylenes display dramatically increased stiffness and yield point, while the increase for other materials is more modest. The data also show that manufacturing processes can significantly affect film properties. To emphasize the need for application-specific properties assessment, we discuss two recent applications using these materials.

  10. A sacrificial process for fabrication of biodegradable polymer membranes with submicron thickness.

    Science.gov (United States)

    Beardslee, Luke A; Stolwijk, Judith; Khaladj, Dimitrius A; Trebak, Mohamed; Halman, Justin; Torrejon, Karen Y; Niamsiri, Nuttawee; Bergkvist, Magnus

    2016-08-01

    A new sacrificial molding process using a single mask has been developed to fabricate ultrathin 2-dimensional membranes from several biocompatible polymeric materials. The fabrication process is similar to a sacrificial microelectromechanical systems (MEMS) process flow, where a mold is created from a material that can be coated with a biodegradable polymer and subsequently etched away, leaving behind a very thin polymer membrane. In this work, two different sacrificial mold materials, silicon dioxide (SiO2 ) and Liftoff Resist (LOR) were used. Three different biodegradable materials; polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and polyglycidyl methacrylate (PGMA), were chosen as model polymers. We demonstrate that this process is capable of fabricating 200-500 nm thin, through-hole polymer membranes with various geometries, pore-sizes and spatial features approaching 2.5 µm using a mold fabricated via a single contact photolithography exposure. In addition, the membranes can be mounted to support rings made from either SU8 or PCL for easy handling after release. Cell culture compatibility of the fabricated membranes was evaluated with human dermal microvascular endothelial cells (HDMECs) seeded onto the ultrathin porous membranes, where the cells grew and formed confluent layers with well-established cell-cell contacts. Furthermore, human trabecular meshwork cells (HTMCs) cultured on these scaffolds showed similar proliferation as on flat PCL substrates, further validating its compatibility. All together, these results demonstrated the feasibility of our sacrificial fabrication process to produce biocompatible, ultra-thin membranes with defined microstructures (i.e., pores) with the potential to be used as substrates for tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1192-1201, 2016. © 2015 Wiley Periodicals, Inc.

  11. Single-molecule imaging reveals topological isomer-dependent diffusion by 4-armed star and dicyclic 8-shaped polymers

    KAUST Repository

    Habuchi, Satoshi

    2015-04-21

    Diffusion dynamics of topological isomers of polymer molecules was investigated at the single-molecule level in a melt state by employing the fluorophore-incorporated 4-armed star and the corresponding doubly-cyclized, 8-shaped poly(THF) chains. While the single-molecule fluorescence imaging experiment revealed that the diffusion of the 4-armed star polymer was described by a single Gaussian distribution, the diffusion of the 8-shaped polymer exhibited a double Gaussian distribution behaviour. We reasoned that the two 8-shaped polymeric isomers have distinct diffusion modes in the melt state, although ensemble-averaged experimental methods cannot detect differences in overall conformational state of the isomers. The single-molecule experiments suggested that one of the 8-shaped polymeric isomer, having the horizontally oriented form, causes an efficient threading with the linear matrix chains which leads to the slower diffusion compared with the corresponding 4-armed star polymer, while the other 8-shaped polymeric isomer, having the vertically oriented form, displayed faster diffusion by the suppression of effective threading with the linear matrix chains due to its contracted chain conformation.

  12. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong; Ding, Yong; Li, Zhou; Song, Jinhui; Wang, Zhong Lin

    2009-01-01

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed

  13. Nanocrystalline LiMn2O4 thin film cathode material prepared by polymer spray pyrolysis method for Li-ion battery

    International Nuclear Information System (INIS)

    Karthick, S.N.; Richard Prabhu Gnanakan, S.; Subramania, A.; Kim, Hee-Je

    2010-01-01

    Nanocrystalline cubic spinel lithium manganese oxide thin film was prepared by a polymer spray pyrolysis method using lithium acetate and manganese acetate precursor solution and polyethylene glycol-4000 as a polymeric binder. The substrate temperature was selected from the thermogravimetric analysis by finding the complete crystallization temperature of LiMn 2 O 4 precursor sample. The deposited LiMn 2 O 4 thin films were annealed at 450, 500 and 600 o C for 30 min. The thin film annealed at 600 o C was found to be the sufficient temperature to form high phase pure nanocrystalline LiMn 2 O 4 thin film. The formation of cubic spinel thin film was confirmed by X-ray diffraction study. Scanning electron microscopy and atomic force microscopy analysis revealed that the thin film annealed at 600 o C was found to be nanocrystalline in nature and the surface of the films were uniform without any crack. The electrochemical charge/discharge studies of the prepared LiMn 2 O 4 film was found to be better compared to the conventional spray pyrolysed thin film material.

  14. Resistive switching of organic–inorganic hybrid devices of conductive polymer and permeable ultra-thin SiO2 films

    Science.gov (United States)

    Yamamoto, Shunsuke; Kitanaka, Takahisa; Miyashita, Tokuji; Mitsuishi, Masaya

    2018-06-01

    We propose a resistive switching device composed of conductive polymer (PEDOT:PSS) and SiO2 ultra-thin films. The SiO2 film was fabricated from silsesquioxane polymer nanosheets as a resistive switching layer. Devices with metal (Ag or Au)∣SiO2∣PEDOT:PSS architecture show good resistive switching performance with set–reset voltages as low as several hundred millivolts. The device properties and the working mechanism were investigated by varying the electrode material, surrounding atmosphere, and SiO2 film thickness. Results show that resistive switching is based on water and ion migration at the PEDOT:PSS∣SiO2 interface.

  15. Single-domain epitaxial silicene on diboride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fleurence, A., E-mail: antoine@jaist.ac.jp; Friedlein, R.; Aoyagi, K.; Yamada-Takamura, Y. [School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Gill, T. G. [School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); London Centre for Nanotechnology, University College London (UCL), London WC1H 0AH (United Kingdom); Department of Chemistry, UCL, London WC1H 0AJ (United Kingdom); Sadowski, J. T. [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States); Copel, M.; Tromp, R. M. [IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Hirjibehedin, C. F. [London Centre for Nanotechnology, University College London (UCL), London WC1H 0AH (United Kingdom); Department of Chemistry, UCL, London WC1H 0AJ (United Kingdom); Department of Physics and Astronomy, UCL, London WC1E 6BT (United Kingdom)

    2016-04-11

    Epitaxial silicene, which forms spontaneously on ZrB{sub 2}(0001) thin films grown on Si(111) wafers, has a periodic stripe domain structure. By adsorbing additional Si atoms on this surface, we find that the domain boundaries vanish, and a single-domain silicene sheet can be prepared without altering its buckled honeycomb structure. The amount of Si required to induce this change suggests that the domain boundaries are made of a local distortion of the silicene honeycomb lattice. The realization of a single domain sheet with structural and electronic properties close to those of the original striped state demonstrates the high structural flexibility of silicene.

  16. Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

    International Nuclear Information System (INIS)

    Vähä-Nissi, Mika; Pitkänen, Marja; Salo, Erkki; Kenttä, Eija; Tanskanen, Anne; Sajavaara, Timo; Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana; Karppinen, Maarit; Harlin, Ali

    2014-01-01

    Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide. It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25 nm ZnO thin film deposited with ozone at 100 °C were quite close to those obtained earlier with ALD Al 2 O 3 of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al 2 O 3 thin films and bacteria promoted antibacterial activity. - Highlights: • Thin films were grown from diethylzinc also with ozone instead of water at 70 and 100 °C. • ZnO films deposited with diethylzinc and ozone had different structures and chemistries. • Best barrier properties obtained with zinc oxide films close to those obtained with Al 2 O 3 • Ozone as oxygen source provided better barrier properties at 100 °C than water. • Both aluminum and zinc oxide thin films showed antimicrobial activity against E. coli

  17. Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Vähä-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Pitkänen, Marja; Salo, Erkki; Kenttä, Eija [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Tanskanen, Anne, E-mail: Anne.Tanskanen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Sajavaara, Timo, E-mail: timo.sajavaara@jyu.fi [University of Jyväskylä, Department of Physics, P.O. Box 35, FI-40014 Jyväskylä (Finland); Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Karppinen, Maarit, E-mail: Maarit.Karppinen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Harlin, Ali [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland)

    2014-07-01

    Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide. It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25 nm ZnO thin film deposited with ozone at 100 °C were quite close to those obtained earlier with ALD Al{sub 2}O{sub 3} of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al{sub 2}O{sub 3} thin films and bacteria promoted antibacterial activity. - Highlights: • Thin films were grown from diethylzinc also with ozone instead of water at 70 and 100 °C. • ZnO films deposited with diethylzinc and ozone had different structures and chemistries. • Best barrier properties obtained with zinc oxide films close to those obtained with Al{sub 2}O{sub 3} • Ozone as oxygen source provided better barrier properties at 100 °C than water. • Both aluminum and zinc oxide thin films showed antimicrobial activity against E. coli.

  18. Single-molecule study on polymer diffusion in a melt state: Effect of chain topology

    KAUST Repository

    Habuchi, Satoshi

    2013-08-06

    We report a new methodology for studying diffusion of individual polymer chains in a melt state, with special emphasis on the effect of chain topology. A perylene diimide fluorophore was incorporated into the linear and cyclic poly(THF)s, and real-time diffusion behavior of individual chains in a melt of linear poly(THF) was measured by means of a single-molecule fluorescence imaging technique. The combination of mean squared displacement (MSD) and cumulative distribution function (CDF) analysis demonstrated the broad distribution of diffusion coefficient of both the linear and cyclic polymer chains in the melt state. This indicates the presence of spatiotemporal heterogeneity of the polymer diffusion which occurs at much larger time and length scales than those expected from the current polymer physics theory. We further demonstrated that the cyclic chains showed marginally slower diffusion in comparison with the linear counterparts, to suggest the effective suppression of the translocation through the threading-entanglement with the linear matrix chains. This coincides with the higher activation energy for the diffusion of the cyclic chains than of the linear chains. These results suggest that the single-molecule imaging technique provides a powerful tool to analyze complicated polymer dynamics and contributes to the molecular level understanding of the chain interaction. © 2013 American Chemical Society.

  19. Single-molecule study on polymer diffusion in a melt state: Effect of chain topology

    KAUST Repository

    Habuchi, Satoshi; Fujiwara, Susumu; Yamamoto, Takuya; Vá cha, Martin; Tezuka, Yasuyuki

    2013-01-01

    We report a new methodology for studying diffusion of individual polymer chains in a melt state, with special emphasis on the effect of chain topology. A perylene diimide fluorophore was incorporated into the linear and cyclic poly(THF)s, and real-time diffusion behavior of individual chains in a melt of linear poly(THF) was measured by means of a single-molecule fluorescence imaging technique. The combination of mean squared displacement (MSD) and cumulative distribution function (CDF) analysis demonstrated the broad distribution of diffusion coefficient of both the linear and cyclic polymer chains in the melt state. This indicates the presence of spatiotemporal heterogeneity of the polymer diffusion which occurs at much larger time and length scales than those expected from the current polymer physics theory. We further demonstrated that the cyclic chains showed marginally slower diffusion in comparison with the linear counterparts, to suggest the effective suppression of the translocation through the threading-entanglement with the linear matrix chains. This coincides with the higher activation energy for the diffusion of the cyclic chains than of the linear chains. These results suggest that the single-molecule imaging technique provides a powerful tool to analyze complicated polymer dynamics and contributes to the molecular level understanding of the chain interaction. © 2013 American Chemical Society.

  20. Thin films of polymer blends deposited by matrix-assisted pulsed laser evaporation: Effects of blending ratios

    International Nuclear Information System (INIS)

    Paun, Irina Alexandra; Ion, Valentin; Moldovan, Antoniu; Dinescu, Maria

    2011-01-01

    In this work, we show successful use of matrix-assisted pulsed laser evaporation (MAPLE) for obtaining thin films of PEG:PLGA blends, in the view of their use for controlled drug delivery. In particular, we investigate the influence of the blending ratios on the characteristics of the films. We show that the roughness of the polymeric films is affected by the ratio of each polymer within the blend. In addition, we perform Fourier transformed infrared spectroscopy (FTIR) measurements and we find that the intensities ratios of the infrared absorption bands of the two polymers are consistent with the blending ratios. Finally, we assess the optical constants of the polymeric films by spectroscopic ellipsometry (SE). We point out that the blending ratios exert an influence on the optical characteristics of the films and we validate the SE results by atomic force microscopy and UV-vis spectrophotometry. In all, we stress that the ratios in which the two polymers are blended have significant impact on the morphology, chemical structure and optical characteristics of the polymeric films deposited by MAPLE.

  1. The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers

    Science.gov (United States)

    Hsu, Yu-Jen

    Organic thin film transistors and ferroelectric polymer (polyvinylidene difluoride) sheet material are integrated to form various sensors for stress/strain, acoustic wave, and Infrared (heat) sensing applications. Different from silicon-based transistors, organic thin film transistors can be fabricated and processed in room-temperature and integrated with a variety of substrates. On the other hand, polyvinylidene difluoride (PVDF) exhibits ferroelectric properties that are highly useful for sensor applications. The wide frequency bandwidth (0.001 Hz to 10 GHz), vast dynamic range (100n to 10M psi), and high elastic compliance (up to 3 percent) make PVDF a more suitable candidate over ceramic piezoelectric materials for thin and flexible sensor applications. However, the low Curie temperature may have impeded its integration with silicon technology. Organic thin film transistors, however, do not have the limitation of processing temperature, hence can serve as transimpedance amplifiers to convert the charge signal generated by PVDF into current signal that are more measurable and less affected by any downstream parasitics. Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation which have complicated the development of array-based PVDF sensors. We have used organic field effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer,PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal which can be detected even in the presence of parasitic capacitances. The device couples the voltage generated by the PVDF film under strain into the gate of the organic thin film transistors (OFET) using an arrangement that allows the full piezoelectric voltage to couple to the channel, while also increasing the charge retention time. A bipolar detector is created by

  2. Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Sara Escorihuela

    2018-03-01

    Full Text Available Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84®, Matrimid 5218®, and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C* for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid®, and 4.30 wt. % for P84®. A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84® ≥ Matrimid® >> 6FDA-6FpDA. The effect of the temperature on the permeance of prepared membranes was studied for H2, CH4, N2, O2, and CO2. As expected, activation energy of permeance for hydrogen was higher than for CO2, resulting in H2/CO2 selectivity increase with temperature. More densely packed polymers lead to materials that are more selective at elevated temperatures.

  3. Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications.

    Science.gov (United States)

    Escorihuela, Sara; Tena, Alberto; Shishatskiy, Sergey; Escolástico, Sonia; Brinkmann, Torsten; Serra, Jose Manuel; Abetz, Volker

    2018-03-07

    Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84 ® , Matrimid 5218 ® , and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C*) for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid ® , and 4.30 wt. % for P84 ® . A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84 ® ≥ Matrimid ® > 6FDA-6FpDA). The effect of the temperature on the permeance of prepared membranes was studied for H₂, CH₄, N₂, O₂, and CO₂. As expected, activation energy of permeance for hydrogen was higher than for CO₂, resulting in H₂/CO₂ selectivity increase with temperature. More densely packed polymers lead to materials that are more selective at elevated temperatures.

  4. A micromotor based on polymer single crystals and nanoparticles: toward functional versatility

    Science.gov (United States)

    Liu, Mei; Liu, Limei; Gao, Wenlong; Su, Miaoda; Ge, Ya; Shi, Lili; Zhang, Hui; Dong, Bin; Li, Christopher Y.

    2014-07-01

    We report a multifunctional micromotor fabricated by the self-assembly technique using multifunctional materials, i.e. polymer single crystals and nanoparticles, as basic building blocks. Not only can this micromotor achieve autonomous and directed movement, it also possesses unprecedented functions, including enzymatic degradation-induced micromotor disassembly, sustained release and molecular detection.We report a multifunctional micromotor fabricated by the self-assembly technique using multifunctional materials, i.e. polymer single crystals and nanoparticles, as basic building blocks. Not only can this micromotor achieve autonomous and directed movement, it also possesses unprecedented functions, including enzymatic degradation-induced micromotor disassembly, sustained release and molecular detection. Electronic supplementary information (ESI) available: Experimental section, Fig. S1-S8 and Video S1-S4. See DOI: 10.1039/c4nr02593h

  5. Advanced Electroactive Single Crystal and Polymer Actuator Concepts for Passive Optics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision piezoelectric single crystal and electroactive polymer actuator concepts?HYBrid Actuation System (HYBAS)...

  6. Enhanced mechanical properties of low-surface energy thin films by simultaneous plasma polymerization of fluorine and epoxy containing polymers

    Energy Technology Data Exchange (ETDEWEB)

    Karaman, Mustafa, E-mail: karamanm@selcuk.edu.tr [Department of Chemical Engineering, Selçuk University, Konya, 42075 (Turkey); Advanced Technology Research & Application Center, Selçuk University, Konya, 42075 (Turkey); Uçar, Tuba [Department of Chemical Engineering, Selçuk University, Konya, 42075 (Turkey)

    2016-01-30

    Graphical abstract: - Highlights: • Thin films of poly(hexafluorobutyl acrylate-glycidyl methacrylate) can be deposited by PECVD. • The coated surfaces are hydrophobic due to the long fluorinated side chains. • The hydrophobicity of the coating is observed to be stable under harsh conditions. • Film durability is attributed to the mechanical strength of the films due to their epoxide functionality. - Abstract: Thin films of poly(2,2,3,4,4,4 hexafluorobutyl acrylate-glycidyl methacrylate) (P(HFBA-GMA) were deposited on different surfaces using an inductively coupled RF plasma reactor. Fluorinated polymer was used to impart hydrophobicity, whereas epoxy polymer was used for improved durability. The deposition at a low plasma power and temperature was suitable for the functionalization of fragile surfaces such as textile fabrics. The coated rough textile surfaces were found to be superhydrophobic with water contact angles greater than 150° due to the high retention of long fluorinated side chains. The hydrophobicity of the surfaces was observed to be stable after many exposures to ultrasonification tests, which is attributed to the mechanical durability of the films due to their epoxide functionality. FTIR and XPS analyses of the deposited films confirmed that the epoxide functionality of the polymers increased with increasing glycidyl methacrylate fraction in the reactor inlet. The modulus and hardness values of the films also increase with increasing epoxide functionality.

  7. Multi-level single mode 2D polymer waveguide optical interconnects using nano-imprint lithography

    NARCIS (Netherlands)

    Khan, M.U.; Justice, J.; Petäjä, J.; Korhonen, T.; Boersma, A.; Wiegersma, S.; Karppinen, M.; Corbett, B.

    2015-01-01

    Single and multi-layer passive optical interconnects using single mode polymer waveguides are demonstrated using UV nano-imprint lithography. The fabrication tolerances associated with imprint lithography are investigated and we show a way to experimentally quantify a small variation in index

  8. Efficient polymer white-light-emitting diodes with a single-emission layer of fluorescent polymer blend

    International Nuclear Information System (INIS)

    Niu Qiaoli; Xu Yunhua; Jiang Jiaxing; Peng Junbiao; Cao Yong

    2007-01-01

    Efficient polymer white-light-emitting diodes (WPLEDs) have been fabricated with a single layer of fluorescent polymer blend. The device structure consists of ITO/PEDOT/PVK/emissive layer/Ba/Al. The emissive layer is a blend of poly(9,9-dioctylfluorene) (PFO), phenyl-substituted PPV derivative (P-PPV) and a copolymer of 9,9-dioctylfluorene and 4,7-di(4-hexylthien-2-yl)-2,1,3-benzothiadiazole (PFO-DHTBT), which, respectively, emits blue, green and red light. The emission of pure and efficient white light was implemented by tuning the blend weight ratio of PFO: P-PPV: PFO-DHTBT to 96:4:0.4. The maximum current efficiency and luminance are, respectively, 7.6 cd/A at 6.7 V and 11930 cd/m 2 at 11.2 V. The CIE coordinates of white-light emission were stable with the drive voltages

  9. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying

    2013-06-02

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

  10. Thermal Vapor Deposition and Characterization of Polymer-Ceramic Nanoparticle Thin Films and Capacitors

    Science.gov (United States)

    Iwagoshi, Joel A.

    Research on alternative energies has become an area of increased interest due to economic and environmental concerns. Green energy sources, such as ocean, wind, and solar power, are subject to predictable and unpredictable generation intermittencies which cause instability in the electrical grid. This problem could be solved through the use of short term energy storage devices. Capacitors made from composite polymer:nanoparticle thin films have been shown to be an economically viable option. Through thermal vapor deposition, we fabricated dielectric thin films composed of the polymer polyvinylidine fluoride (PVDF) and the ceramic nanoparticle titanium dioxide (TiO2). Fully understanding the deposition process required an investigation of electrode and dielectric film deposition. Film composition can be controlled by the mass ratio of PVDF:TiO2 prior to deposition. An analysis of the relationship between the ratio of PVDF:TiO2 before and after deposition will improve our understanding of this novel deposition method. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy were used to analyze film atomic concentrations. The results indicate a broad distribution of deposited TiO2 concentrations with the highest deposited amount at an initial mass concentration of 17% TiO2. The nanoparticle dispersion throughout the film is analyzed through atomic force microscopy and energy dispersive x-ray spectroscopy. Images from these two techniques confirm uniform TiO2 dispersion with cluster size less than 300 nm. These results, combined with spectroscopic analysis, verify control over the deposition process. Capacitors were fabricated using gold parallel plates with PVDF:TiO 2 dielectrics. These capacitors were analyzed using the atomic force microscope and a capacohmeter. Atomic force microscope images confirm that our gold films are acceptably smooth. Preliminary capacohmeter measurements indicate capacitance values of 6 nF and break down voltages of 2.4 V

  11. White-light-emitting diode based on a single-layer polymer

    Science.gov (United States)

    Wang, B. Z.; Zhang, X. P.; Liu, H. M.

    2013-05-01

    A broad-band light-emitting diode was achieved in a single-layer device based on pure poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFB). Electromer emission was observed in the red with a center wavelength of about 620 nm in electroluminescence (EL) spectrum. This kind of emission exhibits strong dependence on the thickness of the PFB layer, so that the shape of the EL spectrum may be adjusted through changing the thickness of the active polymer layer to balance between the intrinsic PFB emission in the blue and the electromer emission in the red. Thus, white light emission may be achieved from such a single-layer single-material diode.

  12. Development of transparent thin film transistors on PES polymer substrates

    International Nuclear Information System (INIS)

    Yun, Eui-Jung; Jung, Jin-Woo; Ko, Kyung-Nam; Song, Young-Wook; Nam, Hyoung; Cho, Nam-Ihn

    2010-01-01

    In this study, we demonstrate ZnO-based transparent thin film transistors (TTFT's) implemented on polyethersulfone (PES) polymer substrates. For the developed TTFT's, radio-frequency magnetron sputter techniques were used to deposit Al-doped ZnO (AZO) at zero oxygen partial pressures for the source, the drain, and the gate-contact electrodes, undoped ZnO at low oxygen partial pressures for the active p-type layer, and SiO 2 for the gate dielectric. The TTFT's were processed at room temperature (RT), except for a 100 .deg. C sputtering step to deposit the AZO source, drain, and gate-contact electrodes. The devices have bottom-gate structures with top contacts, are optically transparent, and operate in an enhancement mode with a threshold voltage of +13 V, a mobility of 0.1 cm 2 /Vs, an on-off ratio of about 0.5 x 10 3 and, a sub-threshold slope of 4.1 V/decade.

  13. Electrical four-point probing of spherical metallic thin films coated onto micron sized polymer particles

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, Sigurd R., E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no; Stokkeland, August Emil; Zhang, Zhiliang; He, Jianying, E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Kristiansen, Helge [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway); Njagi, John; Goia, Dan V. [Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699-5814 (United States); Redford, Keith [Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway)

    2016-07-25

    Micron-sized metal-coated polymer spheres are frequently used as filler particles in conductive composites for electronic interconnects. However, the intrinsic electrical resistivity of the spherical thin films has not been attainable due to deficiency in methods that eliminate the effect of contact resistance. In this work, a four-point probing method using vacuum compatible piezo-actuated micro robots was developed to directly investigate the electric properties of individual silver-coated spheres under real-time observation in a scanning electron microscope. Poly(methyl methacrylate) spheres with a diameter of 30 μm and four different film thicknesses (270 nm, 150 nm, 100 nm, and 60 nm) were investigated. By multiplying the experimental results with geometrical correction factors obtained using finite element models, the resistivities of the thin films were estimated for the four thicknesses. These were higher than the resistivity of bulk silver.

  14. Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal-Organic Framework Thin Film

    KAUST Repository

    Lu, Chunjing

    2014-05-22

    A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous polyaniline with well-defined uniform micropores of 0.84 nm exhibits a high BET surface area of 986 m2 g−1 and a high electric conductivity of 0.125 S cm−1 when doped with I2, which is superior to existing porous conducting materials of porous MOFs, CMPs, and COFs.

  15. Vinyl Flanked Difluorobenzothiadiazole-Dithiophene Conjugated Polymer for High Performance Organic Field-Effect Transistors.

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xianfeng; Sun, Wandong; Chen, Yanlin; Tan, Luxi; Cai, Zheng-Xu; Liu, Zitong; Wang, Lin; Li, Jing; Chen, Wei; Dong, Lichun

    2018-02-21

    Fluorine containing conjugated polymers have been widely applied in high performance organic solar cells, but their use in field-effect transistors is still quite limited. In this work, a conjugated polymer PTFBTV based on difluorobenzothiadiazole (DFBT) and dithiophene was synthesized, utilizing multiple vinylene as linkers. The polymer exhibits a relatively high hole mobility up to 2.0 cm(2) V-1 s(-1) compared with the reported DFBT-oligothiophene based polymers, yet its structural complexity is much simpler. The polymer thin film exhibits a typical 'face on' molecular orientation. A single crystal of its monomer revealed a non-covalent intramolecular contact between fluorine and the neighbouring proton, which strengthens the backbone co-planarity. Meanwhile an intermolecular F...F contact was also observed, which might cause rather scattered lamellar crystallinity for PTFBTV in the solid state.

  16. Simulation study of a single-grip harvester in thinning from below and thinning from above

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, Lars [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Silviculture; Lageson, Haakan [Forest Owner' s Ass. of Norrbotten, Boden (Sweden)

    1999-07-01

    The time consumption and productivity of a single-grip harvester were studied, using a simulation model, when thinning from below and above in eight randomly selected stands. The model estimated the time required for each work element, given machine and tree positions, and tree size. A 2 x 5 factorial design was used with factors thinning type [from below (T{sub b}) and above (T{sub a})] and tree size. Trees were subjectively selected for harvest according to thinning type. Total basal area removal was 30% plot{sup -1}. Approximately 50% more trees were harvested in T{sub b} than in T{sub a}. Time consumption tree{sup -1} was higher for T{sub a} than T{sub b}. Time consumption for machine and boom movements decreased with increasing number of harvested trees, and time for felling and processing of trees increased with harvested mean stem volume. Harvester productivity was 36% higher for T{sub a}, since the increase in harvested mean stem volume was higher than the increase in time consumption tree{sup -1}.

  17. Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers

    KAUST Repository

    Andernach, Rolf

    2015-07-22

    We report the synthesis of a novel polythiophene-based host-guest copolymer incorporating a Pt-porphyrin complex (TTP-Pt) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple timescales and investigated the mechanism of triplet exciton formation. During sensitization, single exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt-porphyrin to the polymer and find that 60% of the complex triplet excitons are transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet-triplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and up-conversion layers.

  18. Polymer-electrolyte-gated nanowire synaptic transistors for neuromorphic applications

    Science.gov (United States)

    Zou, Can; Sun, Jia; Gou, Guangyang; Kong, Ling-An; Qian, Chuan; Dai, Guozhang; Yang, Junliang; Guo, Guang-hua

    2017-09-01

    Polymer-electrolytes are formed by dissolving a salt in polymer instead of water, the conducting mechanism involves the segmental motion-assisted diffusion of ion in the polymer matrix. Here, we report on the fabrication of tin oxide (SnO2) nanowire synaptic transistors using polymer-electrolyte gating. A thin layer of poly(ethylene oxide) and lithium perchlorate (PEO/LiClO4) was deposited on top of the devices, which was used to boost device performances. A voltage spike applied on the in-plane gate attracts ions toward the polymer-electrolyte/SnO2 nanowire interface and the ions are gradually returned after the pulse is removed, which can induce a dynamic excitatory postsynaptic current in the nanowire channel. The SnO2 synaptic transistors exhibit the behavior of short-term plasticity like the paired-pulse facilitation and self-adaptation, which is related to the electric double-effect regulation. In addition, the synaptic logic functions and the logical function transformation are also discussed. Such single SnO2 nanowire-based synaptic transistors are of great importance for future neuromorphic devices.

  19. A nonconjugated radical polymer glass with high electrical conductivity

    Science.gov (United States)

    Joo, Yongho; Agarkar, Varad; Sung, Seung Hyun; Savoie, Brett M.; Boudouris, Bryan W.

    2018-03-01

    Solid-state conducting polymers usually have highly conjugated macromolecular backbones and require intentional doping in order to achieve high electrical conductivities. Conversely, single-component, charge-neutral macromolecules could be synthetically simpler and have improved processibility and ambient stability. We show that poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a nonconjugated radical polymer with a subambient glass transition temperature, underwent rapid solid-state charge transfer reactions and had an electrical conductivity of up to 28 siemens per meter over channel lengths up to 0.6 micrometers. The charge transport through the radical polymer film was enabled with thermal annealing at 80°C, which allowed for the formation of a percolating network of open-shell sites in electronic communication with one another. The electrical conductivity was not enhanced by intentional doping, and thin films of this material showed high optical transparency.

  20. Electrical properties of a new sulfur-containing polymer for optoelectronic application

    Science.gov (United States)

    ElAkemi, ElMehdi; Jaballah, Nejmeddine; Ouada, Hafedh Ben; Majdoub, Mustapha

    2015-06-01

    An original polythiophene derivative was characterized to develop the optoelectronic properties of sulfur-containing π-conjugated polymer. The optical properties of the polymer were investigated by UV-visible absorption spectroscopy and atomic force microscopy. Investigations of the electrical characteristics of polymer diodes are reported. We present current-voltage characteristics and impedance spectroscopy measurements performed on partially sulfur-containing thin films in sandwich structure ITO/sulfur-containing polymer/Al. The conduction mechanisms in these layers are identified to be a space-charge-limited current. The AC electrical transport of the sulfur-containing polymer is studied as a function of frequency (100 Hz-10 MHz) and temperature in impedance spectroscopy analyses. We interpreted Cole-Cole plots in terms of the equivalent circuit model as a single parallel resistance and a capacitance network in series with a relatively small resistance. The evolution of the electrical parameters deduced from fitting of the experimental data is discussed.

  1. Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film

    Science.gov (United States)

    Rajanna, Pramod M.; Gilshteyn, Evgenia P.; Yagafarov, Timur; Aleekseeva, Alena K.; Anisimov, Anton S.; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G.

    2018-03-01

    We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

  2. Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

    KAUST Repository

    Zhao, Kui

    2016-02-03

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Blending of small-molecule organic semiconductors (OSCs) with amorphous polymers is known to yield high performance organic thin film transistors (OTFTs). Vertical stratification of the OSC and polymer binder into well-defined layers is crucial in such systems and their vertical order determines whether the coating is compatible with a top and/or a bottom gate OTFT configuration. Here, we investigate the formation of blends prepared via spin-coating in conditions which yield bilayer and trilayer stratifications. We use a combination of in situ experimental and computational tools to study the competing effects of formulation thermodynamics and process kinetics in mediating the final vertical stratification. It is shown that trilayer stratification (OSC/polymer/OSC) is the thermodynamically favored configuration and that formation of the buried OSC layer can be kinetically inhibited in certain conditions of spin-coating, resulting in a bilayer stack instead. The analysis reveals here that preferential loss of the OSC, combined with early aggregation of the polymer phase due to rapid drying, inhibit the formation of the buried OSC layer. The fluid dynamics and drying kinetics are then moderated during spin-coating to promote trilayer stratification with a high quality buried OSC layer which yields unusually high mobility >2 cm2 V-1 s-1 in the bottom-gate top-contact configuration.

  3. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  4. Fluorescent molecularly imprinted polymer thin films for specific protein detection prepared with dansyl ethylenediamine-conjugated O-acryloyl L-hydroxyproline.

    Science.gov (United States)

    Inoue, Yuki; Kuwahara, Atsushi; Ohmori, Kohei; Sunayama, Hirobumi; Ooya, Tooru; Takeuchi, Toshifumi

    2013-10-15

    Protein-imprinted polymers, capable of specific transduction of protein binding events into fluorescent signal change, were designed and synthesized by using dansyl ethylenediamine-conjugated O-acryloyl L-hydroxyproline (Hyp-En-Dans). Human serum albumin (HSA) was used as a model target protein and HSA-imprinted polymers (HSA-IP) were prepared on glass substrates. Specific fluorescence change was observed for HSA binding on the imprinted polymer thin film, whereas a weaker response was observed for other proteins, including bovine serum albumin, chymotrypsin, lysozyme, and avidin. The binding specificity was found to derive from the rigid structure of the hydrogen-bondable pyrrolidine moiety. Compared with SPR measurements, the non-specific binding caused by the polymer matrix and/or randomly located fluorescent monomer residues that did not compose specific binding sites did not contribute to the observed fluorescence change. These results revealed that the proposed protein-imprinting technique using Hyp-En-Dans could provide a highly selective protein-sensing platform, in which only specific binding events would be detected by fluorescent measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Automatic identification of single- and/or few-layer thin-film material

    DEFF Research Database (Denmark)

    2014-01-01

    One or more digital representations of single- (101) and/or few-layer (102) thin- film material are automatically identified robustly and reliably in a digital image (100), the digital image (100) having a predetermined number of colour components, by - determining (304) a background colour...... component of the digital image (100) for each colour component, and - determining or estimating (306) a colour component of thin-film material to be identified in the digital image (100) for each colour component by obtaining a pre-determined contrast value (C R; C G; C B) for each colour component...

  6. "Silicon millefeuille": From a silicon wafer to multiple thin crystalline films in a single step

    Science.gov (United States)

    Hernández, David; Trifonov, Trifon; Garín, Moisés; Alcubilla, Ramon

    2013-04-01

    During the last years, many techniques have been developed to obtain thin crystalline films from commercial silicon ingots. Large market applications are foreseen in the photovoltaic field, where important cost reductions are predicted, and also in advanced microelectronics technologies as three-dimensional integration, system on foil, or silicon interposers [Dross et al., Prog. Photovoltaics 20, 770-784 (2012); R. Brendel, Thin Film Crystalline Silicon Solar Cells (Wiley-VCH, Weinheim, Germany 2003); J. N. Burghartz, Ultra-Thin Chip Technology and Applications (Springer Science + Business Media, NY, USA, 2010)]. Existing methods produce "one at a time" silicon layers, once one thin film is obtained, the complete process is repeated to obtain the next layer. Here, we describe a technology that, from a single crystalline silicon wafer, produces a large number of crystalline films with controlled thickness in a single technological step.

  7. Thin Single Crystal Silicon Solar Cells on Ceramic Substrates: November 2009 - November 2010

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.; Ravi, K. V.

    2011-06-01

    In this program we have been developing a technology for fabricating thin (< 50 micrometres) single crystal silicon wafers on foreign substrates. We reverse the conventional approach of depositing or forming silicon on foreign substrates by depositing or forming thick (200 to 400 micrometres) ceramic materials on high quality single crystal silicon films ~ 50 micrometres thick. Our key innovation is the fabrication of thin, refractory, and self-adhering 'handling layers or substrates' on thin epitaxial silicon films in-situ, from powder precursors obtained from low cost raw materials. This 'handling layer' has sufficient strength for device and module processing and fabrication. Successful production of full sized (125 mm X 125 mm) silicon on ceramic wafers with 50 micrometre thick single crystal silicon has been achieved and device process flow developed for solar cell fabrication. Impurity transfer from the ceramic to the silicon during the elevated temperature consolidation process has resulted in very low minority carrier lifetimes and resulting low cell efficiencies. Detailed analysis of minority carrier lifetime, metals analysis and device characterization have been done. A full sized solar cell efficiency of 8% has been demonstrated.

  8. Thermo-cleavable polymers: Materials with enhanced photochemical stability

    DEFF Research Database (Denmark)

    Manceau, Matthieu; Petersen, Martin Helgesen; Krebs, Frederik C

    2010-01-01

    Photochemical stability of three thermo-cleavable polymers was investigated as thin films under atmospheric conditions. A significant increase in lifetime was observed once the side-chain was cleaved emphasizing the detrimental effect of solubilizing groups on the photochemical stability of conju......Photochemical stability of three thermo-cleavable polymers was investigated as thin films under atmospheric conditions. A significant increase in lifetime was observed once the side-chain was cleaved emphasizing the detrimental effect of solubilizing groups on the photochemical stability...... of conjugated polymers. In addition to their ease of processing, thermo-cleavable polymers thus also offer a greater intrinsic stability under illumination....

  9. Monte Carlo simulations of confined polymer systems

    NARCIS (Netherlands)

    Vliet, Johannes Henricus van

    1991-01-01

    This thesis considers confined polymer systems. These systems are of considerable interest, e.g., thin polymer films, chromotography of polymer solutions, drag reduction, enhanced oil recovery, stabilization of colloidal dispersions, lubrication and biolubrication. The method used to study these

  10. Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

    Science.gov (United States)

    Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

    2014-08-29

    Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

  11. Broadband Dielectric Spectroscopy and Quasi-Elastic Neutron Scattering on Single-Ion Polymer Conductors

    Science.gov (United States)

    Soles, Christopher; Peng, Hua-Gen; Page, Kirt; Snyder, Chad; Pandy, Ashoutosh; Jeong, Youmi; Runt, James; NIST Collaboration; Pennsylvania Collaboration

    2011-03-01

    The application of solid polymer electrolytes in rechargeable batteries has not been fully realized after decades of research due to its low conductivity. Dramatic increases of the ion conductivity are needed and this progress requires the understanding of conduction mechanism. We address this topic in two fronts, namely, the effect of plasticizer additives and geometric confinement on the charge transfer mechanism. To this end, we combine broadband dielectric spectroscopy (BDS) to characterize the ion mobility and quasi-elastic neutron scattering (QENS) to quantify segmental motion on a single-ion model polymer electrolyte. Deuterated small molecules were used as plasticizers so that the segmental motion of the polymer electrolyte could be monitored by QENS to understand the mechanism behind the increased conductivity. Anodic aluminum oxide (AAO) membranes with well defined channel sizes are used as the matrix to study the transport of ions solvated in a 1D polymer electrolyte.

  12. Scaling from single molecule to macroscopic adhesion at polymer/metal interfaces.

    Science.gov (United States)

    Utzig, Thomas; Raman, Sangeetha; Valtiner, Markus

    2015-03-10

    Understanding the evolution of macroscopic adhesion based on fundamental molecular interactions is crucial to designing strong and smart polymer/metal interfaces that play an important role in many industrial and biomedical applications. Here we show how macroscopic adhesion can be predicted on the basis of single molecular interactions. In particular, we carry out dynamic single molecule-force spectroscopy (SM-AFM) in the framework of Bell-Evans' theory to gain information about the energy barrier between the bound and unbound states of an amine/gold junction. Furthermore, we use Jarzynski's equality to obtain the equilibrium ground-state energy difference of the amine/gold bond from these nonequilibrium force measurements. In addition, we perform surface forces apparatus (SFA) experiments to measure macroscopic adhesion forces at contacts where approximately 10(7) amine/gold bonds are formed simultaneously. The SFA approach provides an amine/gold interaction energy (normalized by the number of interacting molecules) of (36 ± 1)k(B)T, which is in excellent agreement with the interaction free energy of (35 ± 3)k(B)T calculated using Jarzynski's equality and single-molecule AFM experiments. Our results validate Jarzynski's equality for the field of polymer/metal interactions by measuring both sides of the equation. Furthermore, the comparison of SFA and AFM shows how macroscopic interaction energies can be predicted on the basis of single molecular interactions, providing a new strategy to potentially predict adhesive properties of novel glues or coatings as well as bio- and wet adhesion.

  13. Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

    KAUST Repository

    Habuchi, Satoshi

    2016-09-26

    We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

  14. Visualizing spatial and temporal heterogeneity of single molecule rotational diffusion in a glassy polymer by defocused wide-field imaging

    NARCIS (Netherlands)

    Uji-i, Hiroshi; Melnikov, Sergey M.; Deres, Ania; Bergamini, Giacomo; Schryver, Frans De; Herrmann, Andreas; Müllen, Klaus; Enderlein, Jörg; Hofkens, Johan

    2006-01-01

    Defocused wide-field fluorescence microscopy was used to follow the 3D molecular rotational diffusion of a fluorescent probe molecule in a polymer thin film. The technique allows for visualizing the molecular reorientation both in-plane and out-of-plane. The local environmental change driven by

  15. Residual stress in spin-cast polyurethane thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hong; Zhang, Li, E-mail: lizhang@mae.cuhk.edu.hk [Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China); Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Shatin N.T., Hong Kong (China)

    2015-01-19

    Residual stress is inevitable during spin-casting. Herein, we report a straightforward method to evaluate the residual stress in as-cast polyurethane thin films using area shrinkage measurement of films in floating state, which shows that the residual stress is independent of radial location on the substrate and decreased with decreasing film thickness below a critical value. We demonstrate that the residual stress is developed due to the solvent evaporation after vitrification during spin-casting and the polymer chains in thin films may undergo vitrification at an increased concentration. The buildup of residual stress in spin-cast polymer films provides an insight into the size effects on the nature of polymer thin films.

  16. Tailoring of the morphology and chemical composition of thin organosilane microwave plasma polymer layers on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Grundmeier, G.; Thiemann, P.; Carpentier, J.; Shirtcliffe, N.; Stratmann, M

    2004-01-01

    The growth of thin microwave organosilicon plasma polymers on model zinc surfaces was investigated as a function of the film thickness and the oxygen partial pressure during film deposition. The evolution of the topology of the film was studied by atomic force microscopy (AFM). The nano- and micro-roughness was investigated at the inner and the outer surfaces of the plasma polymers. A special etching procedure was developed to reveal the underside of the plasma polymer and thereby its inner surface. Rough films contained voids at the interface, which reduced the polymer/metal contact area. The increase in oxygen partial pressure led to a smoother film growth with a perfect imitation of the substrate topography at the interface. The chemical structure of the films was determined by infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). ToF-SIMS at the outer and the inner surface of the plasma polymers showed that the density of methylsilyl groups increases in the outer surface layer of the plasma polymer and depends on the oxygen partial pressure. The chemical composition of the films could be altered to pure SiO{sub 2} without changing the morphology by using oxygen-plasma post-treatment. This was proved by means of IRRAS and AFM. Chemistry and topology of the films were correlated with the apparent water contact angle. It was found that a linear relationship exists between the nanoscopic roughness of the plasma polymer and the static contact angle of water. Superposition of a nanoscopic roughness of the metal surface and the nanoscopic roughness of methylsilyl-rich films led to ultra-hydrophobic films with water contact angles up to 160 deg.

  17. Measurement of positron reemission from thin single-crystal W(100) films

    International Nuclear Information System (INIS)

    Chen, D.M.; Lynn, K.G.; Pareja, R.; Nielsen, B.

    1985-01-01

    Epitaxial thin single-crystal (100) tungsten films 1000, 2500, and 5000 A thick have been fabricated by high-vacuum electron-beam evaporation. These films were subsequently used as thin-film moderators for the study of the positron-transmission-reemission process with a variable-energy (0--80 keV) monoenergetic positron beam in an ultrahigh-vacuum system. The films were shown to be routinely cleanable by heating first in oxygen (10 -6 Torr) and then in vacuum (10 -9 Torr). Transmission and back reemission of slow positrons from these surfaces was observed. The positron work function, phi/sub +/ has been determined to be approx. =3.0 eV ( +- 0.3 eV). The transmission slow positrons were emitted in a narrow cone with a full width at half maximum of approx. =30 0 consistent with the angular distribution of back-reemission positrons. The reemitted yields as a function of incident positron energy were found to be very different between forward reemission and back reemission. The maximum forward-reemission yields were 18% for 1000-A-thick W film and 12% for 2500-A-thick W film at 5 and 10 keV optimum incident positron energies, respectively. These results show that one can use thin single-crystal tungsten films as positron moderators or remoderators

  18. Single point incremental forming: Formability of PC sheets

    Science.gov (United States)

    Formisano, A.; Boccarusso, L.; Carrino, L.; Lambiase, F.; Minutolo, F. Memola Capece

    2018-05-01

    Recent research on Single Point Incremental Forming of polymers has slightly covered the possibility of expanding the materials capability window of this flexible forming process beyond metals, by demonstrating the workability of thermoplastic polymers at room temperature. Given the different behaviour of polymers compared to metals, different aspects need to be deepened to better understand the behaviour of these materials when incrementally formed. Thus, the aim of the work is to investigate the formability of incrementally formed polycarbonate thin sheets. To this end, an experimental investigation at room temperature was conducted involving formability tests; varying wall angle cone and pyramid frusta were manufactured by processing polycarbonate sheets with different thicknesses and using tools with different diameters, in order to draw conclusions on the formability of polymer sheets through the evaluation of the forming angles and the observation of the failure mechanisms.

  19. Piezoresistivity of mechanically drawn single-walled carbon nanotube (SWCNT) thin films-: mechanism and optimizing principle

    Science.gov (United States)

    Obitayo, Waris

    The individual carbon nanotube (CNT) based strain sensors have been found to have excellent piezoresistive properties with a reported gauge factor (GF) of up to 3000. This GF on the other hand, has been shown to be structurally dependent on the nanotubes. In contrast, to individual CNT based strain sensors, the ensemble CNT based strain sensors have very low GFs e.g. for a single walled carbon nanotube (SWCNT) thin film strain sensor, GF is ~1. As a result, studies which are mostly numerical/analytical have revealed the dependence of piezoresistivity on key parameters like concentration, orientation, length and diameter, aspect ratio, energy barrier height and Poisson ratio of polymer matrix. The fundamental understanding of the piezoresistive mechanism in an ensemble CNT based strain sensor still remains unclear, largely due to discrepancies in the outcomes of these numerical studies. Besides, there have been little or no experimental confirmation of these studies. The goal of my PhD is to study the mechanism and the optimizing principle of a SWCNT thin film strain sensor and provide experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like orientation, network density, bundle diameter (effective tunneling area), and length is studied, and how one can effectively optimize the piezoresistive behavior of a SWCNT thin film strain sensors. To reach this goal, my first research accomplishment involves the study of orientation of SWCNTs and its effect on the piezoresistivity of mechanically drawn SWCNT thin film based piezoresistive sensors. Using polarized Raman spectroscopy analysis and coupled electrical-mechanical test, a quantitative relationship between the strain sensitivity and SWCNT alignment order parameter was established. As compared to randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~6x increase on the GF. My second accomplishment involves studying the

  20. Expandable and retractable self-rolled structures based on metal/polymer thin film for flow sensing

    Science.gov (United States)

    Zhu, Jianzhong; White, Carl; Saadat, Mehdi; Bart-Smith, Hilary

    2015-11-01

    Most aquatic animals such as fish rely heavily on their ability of detect and respond to ambient flows in order to explore and inhabit various habitats or survive predator-prey encounters. Fish utilize neuromasts in their skin surface and lateral lines in their bodies to align themselves while swimming upstream for migration, avoid obstacles, reduce locomotion cost, and detect flow variations caused by potential predators. In this study, a thin film MEMS sensor analogous to a fish neuromast has been designed for flow sensing. Residual stress arises in many thin film materials during processing. Metal and polymer thin film materials with a significant difference in elastic modular were chosen to form a multiple-layer structure. Upon releasing, the structure rolls into a tube due to mechanical property mismatch. The self-rolled tube can expand or retract, depending on the existence of external force such as flow. An embedded strain sensor detects the deformation of the tube and hence senses the ambient flow. Numerical simulations were conducted to optimize the structural design. Experiments were performed in a flow tank to quantify the performance of the sensor. This research is supported by the Office of Naval Research under the MURI Grant N00014-14-1-0533.

  1. Improved Adhesion of Gold Thin Films Evaporated on Polymer Resin: Applications for Sensing Surfaces and MEMS

    Directory of Open Access Journals (Sweden)

    Behrang Moazzez

    2013-05-01

    Full Text Available We present and analyze a method to improve the morphology and mechanical properties of gold thin films for use in optical sensors or other settings where good adhesion of gold to a substrate is of importance and where controlled topography/roughness is key. To improve the adhesion of thermally evaporated gold thin films, we introduce a gold deposition step on SU-8 photoresist prior to UV exposure but after the pre-bake step of SU-8 processing. Shrinkage and distribution of residual stresses, which occur during cross-linking of the SU-8 polymer layer in the post-exposure baking step, are responsible for the higher adhesion of the top gold film to the post-deposition cured SU-8 sublayer. The SU-8 underlayer can also be used to tune the resulting gold film morphology. Our promoter-free protocol is easily integrated with existing sensor microfabrication processes.

  2. Flexible thin film magnetoimpedance sensors

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Fernández, E.; Svalov, A.; Burgoa Beitia, A.; García-Arribas, A.; Larrañaga, A.

    2016-01-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti] 3 /Cu/[FeNi/Ti] 3 films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  3. Flexible thin film magnetoimpedance sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Fernández, E. [BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Svalov, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Burgoa Beitia, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); García-Arribas, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain)

    2016-10-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti]{sub 3}/Cu/[FeNi/Ti]{sub 3} films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  4. Nanoscale thermal-mechanical probe determination of 'softening transitions' in thin polymer films

    International Nuclear Information System (INIS)

    Zhou Jing; Berry, Brian; Douglas, Jack F; Karim, Alamgir; Snyder, Chad R; Soles, Christopher

    2008-01-01

    We report a quantitative study of the softening behavior of glassy polystyrene (PS) films at length scales on the order of 100 nm using nano-thermomechanometry (nano-TM), an emerging scanning probe technique in which a highly doped silicon atomic force microscopy (AFM) tip is resistively heated on the surface of a polymer film. The apparent 'softening temperature' T s of the film is found to depend on the logarithm of the square root of the thermal ramping rate R. This relation allows us to estimate a quasi-equilibrium (or zero rate) softening transition temperature T s0 by extrapolation. We observe marked shifts of T s0 with decreasing film thickness, but the nature of these shifts, and even their sign, depend strongly on both the thermal and mechanical properties of the supporting substrate. Finite element simulations suggest that thin PS films on rigid substrates with large thermal conductivities lead to increasing T s0 with decreasing film thickness, whereas softer, less thermally conductive substrates promote reductions in T s0 . Experimental observations on a range of substrates confirm this behavior and indicate a complicated interplay between the thermal and mechanical properties of the thin PS film and the substrate. This study directly points to relevant factors for quantitative measurements of thermophysical properties of materials at the nanoscale using this nano-TM based method.

  5. Conducting polymer 3D microelectrodes

    DEFF Research Database (Denmark)

    Sasso, Luigi; Vazquez, Patricia; Vedarethinam, Indumathi

    2010-01-01

    Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained...... showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared...

  6. Thermomechanical properties of polymer nanocomposites: Exploring a unified relationship with planar polymer films

    Science.gov (United States)

    Bansal, Amitabh

    The thermal and mechanical response of polymers, which provide limitations to their practical use, are greatly improved by the addition of a small fraction of an inorganic nanofiller. However, the resulting changes in polymer properties are poorly understood, primarily due to the non-uniform spatial distribution of nanoparticles. This research explores the properties of polystyrene filed with silica nanoparticles and illustrates for the first time that the thermodynamic properties of "polymer nanocomposites" are quantitatively equivalent to the well-understood case of planar polymer films with a uniform thickness. These ideas are quantified by drawing a direct analogy between thin film thickness and an appropriate average ligament thickness measured using electron microscopy. The change in polymer glass transition temperatures with decreasing ligament thickness were found to be quantitatively equivalent to the corresponding thin film data. In combination with viscoelastic properties of the nanocomposites that are in quantitative agreement with data from thin films, these conclusions provide a facile means of understanding and predicting the thermomechanical properties and, potentially, the engineering properties of practically relevant polymer nanocomposites. Grafting of high molecular weight polystyrene onto the silica nanoparticles greatly improves the dispersion quality of nanofillers and also provides a means to tailor the thermo-mechanical properties in nanocomposites. It is concluded that the grafted polystyrene is akin to polymer brushes on flat surfaces. The mobility and stiffness of these grafted chains are expected to be low as compared to the free polymer. In this context a mechanism for the increase in glass transition is proposed: (1) the stiff grafted chains will tend to decrease mobility and thus increase glass transition, (2) the extent of interdigitation of the grafted polystyrene into the matrix will determine the extent to which the nanocomposite

  7. Characterization of Thin Films for Polymer Solar Cells

    DEFF Research Database (Denmark)

    Tromholt, Thomas

    , but a large number of additional degradation mechanisms are introduced. Consequently, research in the stability of polymer solar cells is impractical since the extensive timeframe of stability testing reduces the pace of the research. This thesis reports the first results on the response of polymer solar...... cells to concentrated light, both in terms of performance as well as stability. Additionally, concentrated light was used to study some of the mechanisms governing solar cells operation, which are dominant when currents are very high as a consequence of high photon flux. The response in terms......The field of polymer solar cells has undergone an extensive development in recent years after the invention of semiconducting polymers in 1991. Efficiencies have gradually increased to above 10 %, and high throughput processing methods such as roll-to-roll coating allow for production of thousands...

  8. Heparin molecularly imprinted polymer thin flm on gold electrode by plasma-induced graft polymerization for label-free biosensor.

    Science.gov (United States)

    Orihara, Kouhei; Hikichi, Atsushi; Arita, Tomohiko; Muguruma, Hitoshi; Yoshimi, Yasuo

    2018-03-20

    Heparin, a highly sulfated glycosaminoglycan, is an important biomaterial having biological and therapeutic functionalities such as anticoagulation, regeneration, and protein stabilization. This study addresses a label-free quartz crystal microbalance (QCM) biosensor for heparin detection based on a macromolecularly imprinted polymer (MIP) as an artificial recognition element. We demonstrate the novel strategy for MIP in the form of thin film on a gold (Au) electrode with the plasma-induced graft polymerization (PIP) technique. The procedure of PIP is as follows: (i) Hexamethyldisiloxane plasma-polymerized thin film (PPF) as a pre-coating scaffold of active species for PIP (post-polymerization) is deposited on an Au electrode. (ii) The PPF/Au electrode is soaked in an water solution containing heparin (template), (2-(methacryloxy)-ethyl)trimethylammonium chloride acrylamide (functional monomer), acrylamide, and N,N-methylenebisacrylamide (crosslinker). Double bonds of monomer and crosslinker attacked by residually active species in pre-coating PPF cause radical chain reaction. Consequently, a growing polymer network of 20 nm thickness of PIP-MIP thin film is formed and grafted on the PPF/Au surface. (iii) The PIP-MIP/PPF/Au is washed by sodium chloride solution so as to remove the template. Non-imprinted polymer (NIP) is carried out like the same procedure without a template. The AFM, XPS, and QCM measurements show that the PIP process facilitates macromolecularly surface imprinting of template heparin where the template is easily removed and is rapidly rebound to PIP-MIP without a diffusional barrier. The heparin-PIP-MIP specifically binds to heparin compared with heparin analog chondroitin sulfate C (selective factor: 4.0) and a detectable range of heparin in the presence of CS (0.1 wt%) was 0.001-0.1 wt%. The PIP-NIP does not show selectivity between them. The evaluated binding kinetics are association (k a  = 350 ± 100 M -1  s -1

  9. Development of Functional Thin Polymer Films Using a Layer-by-Layer Deposition Technique.

    Science.gov (United States)

    Yoshida, Kentaro

    2017-01-01

    Functional thin films containing insulin were prepared using layer-by-layer (LbL) deposition of insulin and negatively- or positively-charged polymers on the surface of solid substrates. LbL films composed of insulin and negatively-charged polymers such as poly(acrylic acid) (PAA), poly(vinylsulfate) (PVS), and dextran sulfate (DS) were prepared through electrostatic affinity between the materials. The insulin/PAA, insulin/PVS, and insulin/DS films were stable in acidic solutions, whereas they decomposed under physiological conditions as a result of a change in the net electric charge of insulin from positive to negative. Interestingly, the insulin-containing LbL films were stable even in the presence of a digestive-enzyme (pepcin) at pH 1.4 (stomach pH). In contrast, LbL films consisting of insulin and positively-charged polymers such as poly(allylamine hydrochloride) (PAH) decomposed in acidic solutions due to the positive charges of insulin generated in acidic media. The insulin-containing LbL films can be prepared not only on the surface of flat substrates, such as quartz slides, but also on the surface of microparticles, such as poly(lactic acid) (PLA) microbeads. Thus, insulin-containing LbL film-coated PLA microbeads can be handled as a powder. In addition, insulin-containing microcapsules were prepared by coating LbL films on the surface of insulin-doped calcium carbonate (CaCO 3 ) microparticles, followed by dissolution of the CaCO 3 core. The release of insulin from the microcapsules was accelerated at pH 7.4, whereas it was suppressed in acidic solutions. These results suggest the potential use of insulin-containing microcapsules in the development of oral formulations of insulin.

  10. Mechanical integrity of thin inorganic coatings on polymer substrates under quasi-static, thermal and fatigue loadings

    International Nuclear Information System (INIS)

    Leterrier, Y.; Mottet, A.; Bouquet, N.; Gillieron, D.; Dumont, P.; Pinyol, A.; Lalande, L.; Waller, J.H.; Manson, J.-A.E.

    2010-01-01

    The interplay between residual stress state, cohesive and adhesive properties of coatings on substrates is reviewed in this article. Attention is paid to thin inorganic coatings on polymers, characterized by a very high hygro-thermo-mechanical contrast between the brittle and stiff coating and the compliant and soft substrate. An approach to determine the intrinsic, thermal and hygroscopic contributions to the coating residual stress is detailed. The critical strain for coating failure, coating toughness and coating/substrate interface shear strength are derived from the analysis of progressive coating cracking under strain. Electro-fragmentation and electro-fatigue tests in situ in a microscope are described. These methods enable reproducing the thermo-mechanical loads present during processing and service life, hence identifying and modeling the critical conditions for failure. Several case studies relevant to food and pharmaceutical packaging, flexible electronics and thin film photovoltaic devices are discussed to illustrate the benefits and limits of the present methods and models.

  11. Printable Thin Film Supercapacitors Using Single-Walled Carbon Nanotubes

    KAUST Repository

    Kaempgen, Martti

    2009-05-13

    Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics. © 2009 American Chemical Society.

  12. Monte Carlo simulations of lattice models for single polymer systems

    Science.gov (United States)

    Hsu, Hsiao-Ping

    2014-10-01

    Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N ˜ O(10^4). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and sqrt{10}, we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior.

  13. Monte Carlo simulations of lattice models for single polymer systems

    International Nuclear Information System (INIS)

    Hsu, Hsiao-Ping

    2014-01-01

    Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N∼O(10 4 ). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and √(10), we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior

  14. Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jingyu; Xiao, Yihan; Xu, Ting [UCB

    2017-02-20

    Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules with a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. The present studies opened a viable route to achieve designer functional composite thin films via kinetic control.

  15. Unzip instabilities: Straight to oscillatory transitions in the cutting of thin polymer sheets

    Science.gov (United States)

    Reis, P. M.; Kumar, A.; Shattuck, M. D.; Roman, B.

    2008-06-01

    We report an experimental investigation of the cutting of a thin brittle polymer sheet with a blunt tool. It was recently shown that the fracture path becomes oscillatory when the tool is much wider than the sheet thickness. Here we uncover two novel transitions from straight to oscillatory fracture by varying either the tilt angle of the tool or the speed of cutting, respectively. We denote these by angle and speed unzip instabilities and analyze them by quantifying both the dynamics of the crack tip and the final shapes of the fracture paths. Moreover, for the speed unzip instability, the straight crack lip obtained at low speeds exhibits out-of-plane buckling undulations (as opposed to being flat above the instability threshold) suggesting a transition from ductile to brittle fracture.

  16. Polymer and Polymer Gel of Liquid Crystalline Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

    2004-01-01

    It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

  17. Fix it first : utilizing the seismic property analyzer and MMLS to develop guidelines for the use of polymer modified thin lift HMA vs. surface treatments.

    Science.gov (United States)

    2012-09-01

    The main objective of this study was to develop thin lift overlay mixtures with polymer modified asphalt for use in New England. As part of this : research a comprehensive literature review and internet survey was conducted. Moreover, laboratory test...

  18. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique

    Science.gov (United States)

    Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

    2017-01-01

    We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH. PMID:28531106

  19. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique

    Directory of Open Access Journals (Sweden)

    Paola Fanzio

    2017-05-01

    Full Text Available We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT, and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline. The patterning of the fluidic (microfluidic channels and conductive (wiring and electrodes functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH.

  20. Fully-Polymeric pH Sensor Realized by Means of a Single-Step Soft Embossing Technique.

    Science.gov (United States)

    Fanzio, Paola; Chang, Chi-Tung; Skolimowski, Maciej; Tanzi, Simone; Sasso, Luigi

    2017-05-20

    We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH.

  1. Solution-processable ambipolar diketopyrrolopyrrole-selenophene polymer with unprecedentedly high hole and electron mobilities.

    Science.gov (United States)

    Lee, Junghoon; Han, A-Reum; Kim, Jonggi; Kim, Yiho; Oh, Joon Hak; Yang, Changduk

    2012-12-26

    There is a fast-growing demand for polymer-based ambipolar thin-film transistors (TFTs), in which both n-type and p-type transistor operations are realized in a single layer, while maintaining simplicity in processing. Research progress toward this end is essentially fueled by molecular engineering of the conjugated backbones of the polymers and the development of process architectures for device fabrication, which has recently led to hole and electron mobilities of more than 1.0 cm(2) V(-1) s(-1). However, ambipolar polymers with even higher performance are still required. By taking into account both the conjugated backbone and side chains of the polymer component, we have developed a dithienyl-diketopyrrolopyrrole (TDPP) and selenophene containing polymer with hybrid siloxane-solubilizing groups (PTDPPSe-Si). A synergistic combination of rational polymer backbone design, side-chain dynamics, and solution processing affords an enormous boost in ambipolar TFT performance, resulting in unprecedentedly high hole and electron mobilities of 3.97 and 2.20 cm(2) V(-1) s(-1), respectively.

  2. Selective Photophysical Modification on Light-Emitting Polymer Films for Micro- and Nano-Patterning

    Directory of Open Access Journals (Sweden)

    Xinping Zhang

    2016-02-01

    Full Text Available Laser-induced cross-linking in polymeric semiconductors was utilized to achieve micro- and nano-structuring in thin films. Single- and two-photon cross-linking processes led to the reduction in both the refractive index and thickness of the polymer films. The resultant photonic structures combine the features of both relief- and phase-gratings. Selective cross-linking in polymer blend films based on different optical response of different molecular phases enabled “solidification” of the phase-separation scheme, providing a stable template for further photonic structuring. Dielectric and metallic structures are demonstrated for the fabrication methods using cross-linking in polymer films. Selective cross-linking enables direct patterning into polymer films without introducing additional fabrication procedures or additional materials. The diffraction processes of the emission of the patterned polymeric semiconductors may provide enhanced output coupling for light-emitting diodes or distributed feedback for lasers.

  3. Preparation of anatase TiO{sub 2} thin film by low temperature annealing as an electron transport layer in inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Hongche [Department of Chemical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Oh, Seong-Geun, E-mail: seongoh@hanyang.ac.kr [Department of Chemical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Im, Seung Soon, E-mail: imss007@hanyang.ac.kr [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-04-01

    Highlights: • Anatase thin film of TiO{sub 2} was prepared by low temperature annealing. • Anatase TiO{sub 2} colloidal solution was obtained from amorphous form through solvothermal process. • Anatase TiO{sub 2} colloidal solution was used to prepare thin film on ITO glass. • Polymer solar cell fabricated on anatase TiO{sub 2} thin film showed 2.6% of PCE. - Abstract: To prepare the anatase TiO{sub 2} thin films on ITO glass, amorphous TiO{sub 2} colloidal solution was synthesized through the simple sol-gel method by using titanium (IV) isopropoxide as a precursor. This amorphous TiO{sub 2} colloidal solution was spread on ITO glass by spin-coating, then treated at 450 °C to obtain anatase TiO{sub 2} film (for device A). For other TiO{sub 2} films, amorphous TiO{sub 2} colloidal solution was treated through solvothermal process at 180 °C to obtain anatase TiO{sub 2} colloidal solution. This anatase TiO{sub 2} colloidal solution was spread on ITO glass by spin coating, and then annealed at 200 °C (for device B) and 130 °C (for device C), respectively. The average particle size of amorphous TiO{sub 2} colloidal solution was about 1.0 nm and that of anatase TiO{sub 2} colloidal solution was 10 nm. The thickness of TiO{sub 2} films was about 15 nm for all cases. When inverted polymer solar cells were fabricated by using these TiO{sub 2} films as an electron transport layer, the device C showed the highest PCE (2.6%) due to the lack of defect, uniformness and high light absorbance of TiO{sub 2} films. The result of this study can be applied for the preparation of inverted polymer solar cell using TiO{sub 2} films as a buffer layer at low temperature on plastic substrate by roll-to roll process.

  4. Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-05-04

    In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

  5. Nanoimprinted polymer photonic crystal dye lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Smith, Cameron; Buss, Thomas

    2010-01-01

    Optically pumped polymer photonic crystal band-edge dye lasers are presented. The photonic crystal is a rectangular lattice providing laser feedback as well as an optical resonance for the pump light. The lasers are defined in a thin film of photodefinable Ormocore hybrid polymer, doped...

  6. International PolyScene-workshop on polymer electronics. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Topics of this proceedings are: RFID: tagging the opportunities and threats for polymer electronics; polymeric semiconductor development for thin film transistors; hole and electron transport in semiconducting polymers for organic electronics; a circuit based strategy for the development of polymer TFTS; towards a technology for all-polymer electronics; electrically doped organic semiconductors: physics and device applications; organic solar cells and photodetectors; organic solar cells: trends, challenges and positioning in the field of thin-film solar cell technologies; technical production of plastic solar cells: an overview; optical and ESR studies on polymer/fullerene composites for solar cells; targets for OTFT development for active matrix displays; reflective electroactive display (READ) technology and opportunities in printed devices; OFETs, OLEDs, OLDs: organic devices for future polytronic systems; design of active polymer materials and their application in electronic devices; blue emitting ALQ3 for full color organic displays; technologies for the reel-to-reel production of flexible polytronic systems; new developments in polyester films for flexible electronics; printed conductive polymer structures; non-lithographic patterning of polymer transistors; laser structuring- a method for polymer and metal patterning; direct printing of polymer transistor circuits; molecular design of interphases - the key for the development of reliable polymer based products; wafer level packaging - encapsulation of micro structures.

  7. On the Wrapping of Polyglycolide, Poly(Ethylene Oxide), and Polyketone Polymer Chains Around Single-Walled Carbon Nanotubes Using Molecular Dynamics Simulations

    Science.gov (United States)

    Rouhi, S.; Alizadeh, Y.; Ansari, R.

    2015-02-01

    By using molecular dynamics simulations, the interaction between a single-walled carbon nanotube and three different polymers has been studied in this work. The effects of various parameters such as the nanotube geometry and temperature on the interaction energy and radius of gyration of polymers have been explored. By studying the snapshots of polymers along the single-walled carbon nanotube, it has been shown that 50 ps can be considered as a suitable time after which the shape of polymer chains around the nanotube remains almost unchanged. It is revealed that the effect of temperature on the interaction energy and radius of gyration of polymers in the range of 250 to 500 K is not significant Also, it is shown that the interaction energy depends on the nanotube diameter.

  8. Preventing Thin Film Dewetting via Graphene Capping.

    Science.gov (United States)

    Cao, Peigen; Bai, Peter; Omrani, Arash A; Xiao, Yihan; Meaker, Kacey L; Tsai, Hsin-Zon; Yan, Aiming; Jung, Han Sae; Khajeh, Ramin; Rodgers, Griffin F; Kim, Youngkyou; Aikawa, Andrew S; Kolaczkowski, Mattew A; Liu, Yi; Zettl, Alex; Xu, Ke; Crommie, Michael F; Xu, Ting

    2017-09-01

    A monolayer 2D capping layer with high Young's modulus is shown to be able to effectively suppress the dewetting of underlying thin films of small organic semiconductor molecule, polymer, and polycrystalline metal, respectively. To verify the universality of this capping layer approach, the dewetting experiments are performed for single-layer graphene transferred onto polystyrene (PS), semiconducting thienoazacoronene (EH-TAC), gold, and also MoS 2 on PS. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS 2 substantially suppress surface fluctuations and thus dewetting. As long as the uncovered area is smaller than the fluctuation wavelength of the thin film in a dewetting process via spinodal decomposition, the dewetting should be suppressed. The 2D monolayer-capping approach opens up exciting new possibilities to enhance the thermal stability and expands the processing parameters for thin film materials without significantly altering their physical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System

    Directory of Open Access Journals (Sweden)

    Somen K. Bhudolia

    2017-03-01

    Full Text Available For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA thermoplastic matrix, Elium®. Vacuum assisted resin infusion (VARI process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS and NCF with novel reactive thermoplastic (TP resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented.

  10. Optimizing Polymer Infusion Process for Thin Ply Textile Composites with Novel Matrix System.

    Science.gov (United States)

    Bhudolia, Somen K; Perrotey, Pavel; Joshi, Sunil C

    2017-03-15

    For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs) composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA) thermoplastic matrix, Elium ® . Vacuum assisted resin infusion (VARI) process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS) and NCF with novel reactive thermoplastic (TP) resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented.

  11. Thiophene-rich fused-aromatic thienopyrazine acceptor for donor–acceptor low band-gap polymers for OTFT and polymer solar cell applications

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Thiophene enriched fused-aromatic thieno[3,4-b]pyrazine systems were designed and employed to produce low band gap polymers (Eg = 1.0-1.4 eV) when copolymerized with fluorene and cyclopentadithiophene. The copolymers are mainly investigated for organic thin film transistor and organic photovoltaic applications. Molecular packing in the thin films of these polymers was investigated using Grazing incidence X-ray Scattering. Although both fluorene and cyclopentadithiophene polymers follow similar face to face π-π stacking, the latter polymers show much smaller lamellar d-spacings due to side-chain interdigitation between the lamellae. This lead to the higher charge carrier mobilities in cyclopentadithiophene polymers (up to 0.044 cm2/V.s) compared to fluorene polymers (up to 8.1 × 10-3 cm2/V.s). Power conversion efficiency of 1.4% was achieved using fluorene copolymer in solar cells with a fullerene derivative as an acceptor. Although the cyclopentadithiophene polymers show lower band gaps with higher absorption coefficients compared to fluorene copolymers, but the power conversion efficiencies in solar cells of these polymers are low due to their low ionization potentials. © The Royal Society of Chemistry 2010.

  12. Unusual dewetting of thin polymer films in liquid media containing a poor solvent and a nonsolvent.

    Science.gov (United States)

    Xu, Lin; Sharma, Ashutosh; Joo, Sang Woo; Liu, Hui; Shi, Tongfei

    2014-12-16

    We investigate the control of pattern size and kinetics in spontaneous dewetting of thin polymer films (polystyrene) that are stable to thermal annealing by annealing in a poor solvent (acetone)/nonsolvent (ethanol or n-hexane) liquid mixture. Dewetting occurs by the formation and growth of circular holes that coalesce to form droplets. The influence of the nature and the volume fraction of the nonsolvents on the contact angle of polymer droplets, number density of holes, and the kinetics of holes formation and growth is studied. Addition of ethanol greatly increases the hole density and slows down the kinetics substantially, while affecting only a small change in wettability. n-Hexane addition shows an interesting nonmonotonic response in decreasing the hole density and contact angle in the volume fraction range of 0-0.3 but an opposite effect beyond that. Although the two nonsolvents chosen cannot by themselves induce dewetting, their relative affinity for the solid substrate vis-à-vis acetone can strongly influence the observed dewetting scenarios that are not understood by the existing theoretical considerations. n-Hexane, for example, has great affinity for silicon substrate. In addition to the changes in wettability, viscosity, and film interfacial tension engendered by the nonsolvents, the possibility of the formation of adsorbed liquid layers at the substrate-polymer interface, which can modify the interfacial friction and slippage, needs to be considered.

  13. Classical ultraviolet photoelectron spectroscopy of polymers

    International Nuclear Information System (INIS)

    Salaneck, W.R.

    2009-01-01

    Although X-ray photoelectron spectroscopy of polymers was well established by Clark and coworkers in the 1970s, ultraviolet photoelectron spectroscopy of polymer films, was developed later. Previous to the 1970s, the first attempts to use ultraviolet light on polymer films took the form of appearance potential (valence band edge) measurements. Only some years later could the full valence band region of thin polymer films, including insulating polymers, semiconducting polymers and electrically conducting polymers. The development of what might be termed 'classical ultraviolet photoelectron spectroscopy' of polymer films may be loosely based upon a variety of issues, including adapting thin polymer film technology to ultra high vacuum studies, the widespread use of helium resonance lamps for studies of solid surfaces, the combined advent of practical and sufficient theoretical-computational methods. The advent of, and the use of, easily available synchrotron radiation for multi-photon spectroscopies, nominally in the area of the near UV, is not included in the term 'classical'. At the same time, electrically conducting polymers were discovered, leading to applications of the corresponding semiconducting polymers, which added technologically driven emphasis to this development of ultraviolet photoelectron spectroscopy for polymer materials. This paper traces a limited number of highlights in the evolution of ultraviolet photoelectron spectroscopy of polymers, from the 1970s through to 2008. Also, since this issue is dedicated to Prof. Kazuhiko Seki, who has been a friend and competitor for over two decades, the author relies on some of Prof. Seki's earlier research, unpublished, on who-did-what-first. Prof. Seki's own contributions to the field, however, are discussed in other articles in this issue.

  14. X-ray beam monitor made by thin-film CVD single-crystal diamond.

    Science.gov (United States)

    Marinelli, Marco; Milani, E; Prestopino, G; Verona, C; Verona-Rinati, G; Angelone, M; Pillon, M; Kachkanov, V; Tartoni, N; Benetti, M; Cannatà, D; Di Pietrantonio, F

    2012-11-01

    A novel beam position monitor, operated at zero bias voltage, based on high-quality chemical-vapor-deposition single-crystal Schottky diamond for use under intense synchrotron X-ray beams was fabricated and tested. The total thickness of the diamond thin-film beam monitor is about 60 µm. The diamond beam monitor was inserted in the B16 beamline of the Diamond Light Source synchrotron in Harwell (UK). The device was characterized under monochromatic high-flux X-ray beams from 6 to 20 keV and a micro-focused 10 keV beam with a spot size of approximately 2 µm × 3 µm square. Time response, linearity and position sensitivity were investigated. Device response uniformity was measured by a raster scan of the diamond surface with the micro-focused beam. Transmissivity and spectral responsivity versus beam energy were also measured, showing excellent performance of the new thin-film single-crystal diamond beam monitor.

  15. The single-phase multiferroic oxides: from bulk to thin film

    International Nuclear Information System (INIS)

    Prellier, W; Singh, M P; Murugavel, P

    2005-01-01

    Complex perovskite oxides exhibit a rich spectrum of properties, including magnetism, ferroelectricity, strongly correlated electron behaviour, superconductivity and magnetoresistance, which have been research areas of great interest among the scientific and technological community for decades. There exist very few materials which exhibit multiple functional properties; one such class of materials is called the multiferroics. Multiferroics are interesting because they exhibit simultaneously ferromagnetic and ferroelectric polarizations and a coupling between them. Due to the nontrivial lattice coupling between the magnetic and electronic domains (the magnetoelectric effect), the magnetic polarization can be switched by applying an electric field; likewise the ferroelectric polarization can be switched by applying a magnetic field. As a consequence, multiferroics offer rich physics and novel devices concepts, which have recently become of great interest to researchers. In this review article the recent experimental status, for both the bulk single phase and the thin film form, has been presented. Current studies on the ceramic compounds in the bulk form including Bi(Fe,Mn)O 3 , REMnO 3 and the series of REMn 2 O 5 single crystals (RE = rare earth) are discussed in the first section and a detailed overview on multiferroic thin films grown artificially (multilayers and nanocomposites) is presented in the second section. (topical review)

  16. Short wave infrared hyperspectral imaging for recovered post-consumer single and mixed polymers characterization

    Science.gov (United States)

    Bonifazi, Giuseppe; Palmieri, Roberta; Serranti, Silvia

    2015-03-01

    Postconsumer plastics from packing and packaging represent about the 60% of the total plastic wastes (i.e. 23 million of tons) produced in Europe. The EU Directive (2014/12/EC) fixes as target that the 60%, by weight, of packaging waste has to be recovered, or thermally valorized. When recovered, the same directive established that packaging waste has to be recycled in a percentage ranging between 55% (minimum) and 60% (maximum). The non-respect of these rules can produce that large quantities of end-of-life plastic products, specifically those utilized for packaging, are disposed-off, with a strong environmental impact. The application of recycling strategies, finalized to polymer recovery, can represent an opportunity to reduce: i) not renewable raw materials (i.e. oil) utilization, ii) carbon dioxide emissions and iii) amount of plastic waste disposed-off. Aim of this work was to perform a full characterization of different end-of-life polymers based products, constituted not only by single polymers but also of mixtures, in order to realize their identification for quality control and/or certification assessment. The study was specifically addressed to characterize the different recovered products as resulting from a recycling plant where classical processing flow-sheets, based on milling, classification and separation, are applied. To reach this goal, an innovative sensing technique, based on the utilization of a HyperSpectral[b] I[/b]maging (HSI) device working in the SWIR region (1000-2500 nm), was investigated. Following this strategy, single polymers and/or mixed polymers recovered were correctly recognized. The main advantage of the proposed approach is linked to the possibility to perform "on-line" analyses, that is directly on the different material flow streams, as resulting from processing, without any physical sampling and classical laboratory "off-line" determination.

  17. Photocatalytic Anatase TiO2 Thin Films on Polymer Optical Fiber Using Atmospheric-Pressure Plasma.

    Science.gov (United States)

    Baba, Kamal; Bulou, Simon; Choquet, Patrick; Boscher, Nicolas D

    2017-04-19

    Due to the undeniable industrial advantages of low-temperature atmospheric-pressure plasma processes, such as low cost, low temperature, easy implementation, and in-line process capabilities, they have become the most promising next-generation candidate system for replacing thermal chemical vapor deposition or wet chemical processes for the deposition of functional coatings. In the work detailed in this article, photocatalytic anatase TiO 2 thin films were deposited at a low temperature on polymer optical fibers using an atmospheric-pressure plasma process. This method overcomes the challenge of forming crystalline transition metal oxide coatings on polymer substrates by using a dry and up-scalable method. The careful selection of the plasma source and the titanium precursor, i.e., titanium ethoxide with a short alkoxy group, allowed the deposition of well-adherent, dense, and crystalline TiO 2 coatings at low substrate temperature. Raman and XRD investigations showed that the addition of oxygen to the precursor's carrier gas resulted in a further increase of the film's crystallinity. Furthermore, the films deposited in the presence of oxygen exhibited a better photocatalytic activity toward methylene blue degradation assumedly due to their higher amount of photoactive {101} facets.

  18. Radiation effects of ion beams on polymers

    International Nuclear Information System (INIS)

    Tagawa, Seiichi

    1993-01-01

    Recent progress in the radiation effects of ion beams on polymers are reviewed briefly. Our recent work on the radiation effects of ion beams on polystyrene thin films on silicon wafers and time resolved emission studies on polymers are described. (orig.)

  19. Fused electron deficient semiconducting polymers for air stable electron transport

    KAUST Repository

    Onwubiko, Ada

    2018-01-23

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  20. Fused electron deficient semiconducting polymers for air stable electron transport

    KAUST Repository

    Onwubiko, Ada; Yue, Wan; Jellett, Cameron; Xiao, Mingfei; Chen, Hung-Yang; Ravva, Mahesh Kumar; Hanifi, David A.; Knall, Astrid-Caroline; Purushothaman, Balaji; Nikolka, Mark; Flores, Jean-Charles; Salleo, Alberto; Bredas, Jean-Luc; Sirringhaus, Henning; Hayoz, Pascal; McCulloch, Iain

    2018-01-01

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  1. Fused electron deficient semiconducting polymers for air stable electron transport.

    Science.gov (United States)

    Onwubiko, Ada; Yue, Wan; Jellett, Cameron; Xiao, Mingfei; Chen, Hung-Yang; Ravva, Mahesh Kumar; Hanifi, David A; Knall, Astrid-Caroline; Purushothaman, Balaji; Nikolka, Mark; Flores, Jean-Charles; Salleo, Alberto; Bredas, Jean-Luc; Sirringhaus, Henning; Hayoz, Pascal; McCulloch, Iain

    2018-01-29

    Conventional semiconducting polymer synthesis typically involves transition metal-mediated coupling reactions that link aromatic units with single bonds along the backbone. Rotation around these bonds contributes to conformational and energetic disorder and therefore potentially limits charge delocalisation, whereas the use of transition metals presents difficulties for sustainability and application in biological environments. Here we show that a simple aldol condensation reaction can prepare polymers where double bonds lock-in a rigid backbone conformation, thus eliminating free rotation along the conjugated backbone. This polymerisation route requires neither organometallic monomers nor transition metal catalysts and offers a reliable design strategy to facilitate delocalisation of frontier molecular orbitals, elimination of energetic disorder arising from rotational torsion and allowing closer interchain electronic coupling. These characteristics are desirable for high charge carrier mobilities. Our polymers with a high electron affinity display long wavelength NIR absorption with air stable electron transport in solution processed organic thin film transistors.

  2. Photon emission by electrons and positrons traversing thin single crystal

    International Nuclear Information System (INIS)

    Ol'chak, A.S.

    1984-01-01

    Radiation emission by planar channeled particles (electrons, positrons) in a thin single crystal of thickness L is considered. It is shown that for L approximately πb/THETAsub(L) (b is the lattice constant, THETA sub(L) the Lindhard angle) besides the main spontaneous channeling maxima there exist auxiliary interference maxima, the positions of all the maxima depending on L. The dependence of the radiation spectral intensity on crystal thickness is discussed

  3. In-situ spectroscopic ellipsometry for studies of thin films and membranes

    NARCIS (Netherlands)

    Ogieglo, Wojciech

    2014-01-01

    The properties of a thin polymer film can be significantly affected by the presence of a penetrant. It is also known that the behavior of ultra-thin polymer films (<100 nm) may deviate from the bulk behavior. This sole impact of film thickness reduction is often referred to as a nano-confinement

  4. Effect of chain stiffness on the structure of single-chain polymer nanoparticles

    Science.gov (United States)

    Moreno, Angel J.; Bacova, Petra; Lo Verso, Federica; Arbe, Arantxa; Colmenero, Juan; Pomposo, José A.

    2018-01-01

    Polymeric single-chain nanoparticles (SCNPs) are soft nano-objects synthesized by purely intramolecular cross-linking of single polymer chains. By means of computer simulations, we investigate the conformational properties of SCNPs as a function of the bending stiffness of their linear polymer precursors. We investigate a broad range of characteristic ratios from the fully flexible case to those typical of bulky synthetic polymers. Increasing stiffness hinders bonding of groups separated by short contour distances and increases looping over longer distances, leading to more compact nanoparticles with a structure of highly interconnected loops. This feature is reflected in a crossover in the scaling behaviour of several structural observables. The scaling exponents change from those characteristic for Gaussian chains or rings in θ-solvents in the fully flexible limit, to values resembling fractal or ‘crumpled’ globular behaviour for very stiff SCNPs. We characterize domains in the SCNPs. These are weakly deformable regions that can be seen as disordered analogues of domains in disordered proteins. Increasing stiffness leads to bigger and less deformable domains. Surprisingly, the scaling behaviour of the domains is in all cases similar to that of Gaussian chains or rings, irrespective of the stiffness and degree of cross-linking. It is the spatial arrangement of the domains which determines the global structure of the SCNP (sparse Gaussian-like object or crumpled globule). Since intramolecular stiffness can be varied through the specific chemistry of the precursor or by introducing bulky side groups in its backbone, our results propose a new strategy to tune the global structure of SCNPs.

  5. Sensitive thermal transitions of nanoscale polymer samples using the bimetallic effect: application to ultra-thin polythiophene.

    Science.gov (United States)

    Ahumada, O; Pérez-Madrigal, M M; Ramirez, J; Curcó, D; Esteves, C; Salvador-Matar, A; Luongo, G; Armelin, E; Puiggalí, J; Alemán, C

    2013-05-01

    A sensitive nanocalorimetric technology based on microcantilever sensors is presented. The technology, which combines very short response times with very small sample consumption, uses the bimetallic effect to detect thermal transitions. Specifically, abrupt variations in the Young's modulus and the thermal expansion coefficient produced by temperature changes have been employed to detect thermodynamic transitions. The technology has been used to determine the glass transition of poly(3-thiophene methyl acetate), a soluble semiconducting polymer with different nanotechnological applications. The glass transition temperature determined using microcantilevers coated with ultra-thin films of mass = 10(-13) g is 5.2 °C higher than that obtained using a conventional differential scanning calorimeter for bulk powder samples of mass = 5 × 10(-3) g. Atomistic molecular dynamics simulations on models that represent the bulk powder and the ultra-thin films have been carried out to provide understanding and rationalization of this feature. Simulations indicate that the film-air interface plays a crucial role in films with very small thickness, affecting both the organization of the molecular chains and the response of the molecules against the temperature.

  6. Phthalimide containing donor-acceptor polymers for effective dispersion of single-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Baris Yilmaz

    2015-08-01

    Full Text Available Single-walled carbon nanotubes have been dispersed by novel phthalimide containing donor-acceptor type copolymers in organic media. Brominated phthalimide comonomer has been copolymerized with several electron rich structures using Suzuki and Stille coupling reactions. Carbon nanotube dispersion capability of the resultant polymers has been assessed by exploiting the non-covalent interaction of nanotube surface with the pi-system of conjugated backbone of polymers. Four polymers have been found to be good candidates for individually dispersing nanotubes in solution. In order to identify the dispersed nanotube species, 2D excitation-emission map and Raman spectroscopy have been performed. Molecular dynamics modelling has been utilized to reveal the binding energies of dispersants with the nanotube surface and the simulation results have been compared with the experimental findings. Both experimental and theoretical results imply the presence of a complex mechanism that governs the extent of dispersion capacity and selectivity of each conjugated polymeric dispersant in solubilizing carbon nanotubes.

  7. Stability and dewetting of metal nanoparticle filled thin polymer films: control of instability length scale and dynamics.

    Science.gov (United States)

    Mukherjee, Rabibrata; Das, Soma; Das, Anindya; Sharma, Satinder K; Raychaudhuri, Arup K; Sharma, Ashutosh

    2010-07-27

    We investigate the influence of gold nanoparticle addition on the stability, dewetting, and pattern formation in ultrathin polymer-nanoparticle (NP) composite films by examining the length and time scales of instability, morphology, and dynamics of dewetting. For these 10-50 nm thick (h) polystyrene (PS) thin films containing uncapped gold nanoparticles (diameter approximately 3-4 nm), transitions from complete dewetting to arrested dewetting to absolute stability were observed depending on the concentration of the particles. Experiments show the existence of three distinct stability regimes: regime 1, complete dewetting leading to droplet formation for nanoparticle concentration of 2% (w/w) or below; regime 2, partial dewetting leading to formation of arrested holes for NP concentrations in the range of 3-6%; and regime 3, complete inhibition of dewetting for NP concentrations of 7% and above. Major results are (a) length scale of instability, where lambdaH approximately hn remains unchanged with NP concentration in regime 1 (n approximately 2) but increases in regime 2 with a change in the scaling relation (n approximately 3-3.5); (b) dynamics of instability and dewetting becomes progressively sluggish with an increase in the NP concentration; (c) there are distinct regimes of dewetting velocity at low NP concentrations; (d) force modulation AFM, as well as micro-Raman analysis, shows phase separation and aggregation of the gold nanoparticles within each dewetted polymer droplet leading to the formation of a metal core-polymer shell morphology. The polymer shell could be removed by washing in a selective solvent, thus exposing an array of bare gold nanoparticle aggregates.

  8. Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

    Energy Technology Data Exchange (ETDEWEB)

    Potthoff, H.H. (Technische Univ. Braunschweig (Germany, F.R.). Inst. fuer Metallphysik und Nukleare Festkoerperphysik)

    1983-05-16

    Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 ..mu..m, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 ..mu..m) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations.

  9. Single-step generation of metal-plasma polymer multicore@shell nanoparticles from the gas phase.

    Science.gov (United States)

    Solař, Pavel; Polonskyi, Oleksandr; Olbricht, Ansgar; Hinz, Alexander; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Faupel, Franz; Biederman, Hynek

    2017-08-17

    Nanoparticles composed of multiple silver cores and a plasma polymer shell (multicore@shell) were prepared in a single step with a gas aggregation cluster source operating with Ar/hexamethyldisiloxane mixtures and optionally oxygen. The size distribution of the metal inclusions as well as the chemical composition and the thickness of the shells were found to be controlled by the composition of the working gas mixture. Shell matrices ranging from organosilicon plasma polymer to nearly stoichiometric SiO 2 were obtained. The method allows facile fabrication of multicore@shell nanoparticles with tailored functional properties, as demonstrated here with the optical response.

  10. Epitaxial growth of thin single-crystals and their quality study by Rutherford scattering in channeling conditions

    International Nuclear Information System (INIS)

    Kirsch, Robert.

    1975-01-01

    Some aspects of thin crystalline layers are reminded: vacuum deposition, epitaxial growth, annealing and interdiffusion ion channeling and scattering of 1-2MeV helium ions are used to study the crystalline quality, the annealing effects and in some cases the interdiffusion in epitaxial multilayers of silver, copper gold and nickel. Thin single-crystals of gold and nickel oriented (III) plan parallel to the surface were obtained by successive epitaxial growth from muscovite mica clivages. The mounting techniques of single crystalline, self-supporting, 300 to 1200 Angstroems thick, gold and nickel targets of 3mm diameter are described. The gold single-crystals have dislocation densities of 10 8 cm -2 and the various epitaxial layers are obtained without twinning [fr

  11. Enhanced thermal conductance of polymer composites through embeddingaligned carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Dale K. Hensley

    2016-07-01

    Full Text Available The focus of this work is to find a more efficient method of enhancing the thermal conductance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 μm and a higher thermal conductance between 25–40 μm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers.

  12. Study of Hydrophobic and Ionizable Hydrophilic Copolymers at Polymer/Solid and Polymer/Liquid Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Perahia, Dvora

    2011-11-01

    Joint experimental-computational efforts were set to characterize the interfacial effects on the structure and dynamics of polymers consisting of highly rigid hydrophilic-ionizable and hydrophobic sub-units within one polymeric chain casted into thin films of several molecular dimensions. Focusing on the ultra thin film region we separate out the interfacial effects from bulk characteristics. Specifically, the study sought to: identify the parameters that control the formation of a stable polymer-solid interface. The study consists of two components, experimental investigations and computational efforts. The experimental component was designed to derive empirical trends that can be used to correlate the set of coupled polymer molecular parameters with the interfacial characteristics of these polymers, and their response to presence of solvents. The computational study was designed to provide molecular insight into the ensemble averages provided by the experimental efforts on multiple length scales from molecular dimensions, to the nanometer lengths to a macroscopic understanding of solvent interactions with structured polymers. With the ultimate goal of correlating molecular parameters to structure, dynamics and properties of ionic polymers, the first stage of the research began with the study of two systems, one which allowed tailoring the flexibility of the backbone without the presence of ionic groups, but with a potential to sulfonate groups at a later stage, and a polymer whose backbone is rigid and the density of the ionic group can be varied. The combined experimental and computational studies significantly extended the understanding of polymers at interfaces from model systems to polydispersed copolymers with blocks of varying nature and complexity. This new insight directly affects the design of polymers for sustainable energy applications from batteries and fuel cells to solar energy.

  13. Influence of the physical–chemical properties of polyaniline thin films on the final sensitivity of varied field effect sensors

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Hugo José Nogueira Pedroza Dias, E-mail: hugodiasmello@usp.br; Heimfarth, Tobias; Mulato, Marcelo

    2015-06-15

    We investigated the use of electrodeposited polyaniline (PANI) thin sensing films in pH sensors. Two configurations of the Extended Gate Field Effect Transistor (EGFET) sensor were studied: the Single EGFET (S-EGFET) and the Instrumental Amplifier EGFET (IA-EGFET) setups. The films were analyzed in both systems and the sensitivity and linearity of each sensor were compared. Initial sensitivities (70–80 mV/pH) measured in the IA-EGFET were reduced due to polymer bulk protonation after a prior measurement in the S-EGFET system. Films with high amount of deposited polymer had their sensitivities least reduced. Bulk protonation occurred due to the step potential applied to the reference electrode in the S-EGFET system. These changes were also analyzed by scanning electron microscopy (SEM), visible reflectance spectroscopy and evaluation of CIE L*a*b* color scale. PANI pH EGFET sensors exhibited good linearity and stability that along with their high sensitivity, easy processing and low cost film production have large potential applications. - Highlights: • Electrodeposited polyaniline thin films were analyzed in two EGFET setups. • Polymer protonation provided changeable sensitivities. • Color and morphological variation confirm polymer aggregation and electrical changes.

  14. Influence of the physical–chemical properties of polyaniline thin films on the final sensitivity of varied field effect sensors

    International Nuclear Information System (INIS)

    Mello, Hugo José Nogueira Pedroza Dias; Heimfarth, Tobias; Mulato, Marcelo

    2015-01-01

    We investigated the use of electrodeposited polyaniline (PANI) thin sensing films in pH sensors. Two configurations of the Extended Gate Field Effect Transistor (EGFET) sensor were studied: the Single EGFET (S-EGFET) and the Instrumental Amplifier EGFET (IA-EGFET) setups. The films were analyzed in both systems and the sensitivity and linearity of each sensor were compared. Initial sensitivities (70–80 mV/pH) measured in the IA-EGFET were reduced due to polymer bulk protonation after a prior measurement in the S-EGFET system. Films with high amount of deposited polymer had their sensitivities least reduced. Bulk protonation occurred due to the step potential applied to the reference electrode in the S-EGFET system. These changes were also analyzed by scanning electron microscopy (SEM), visible reflectance spectroscopy and evaluation of CIE L*a*b* color scale. PANI pH EGFET sensors exhibited good linearity and stability that along with their high sensitivity, easy processing and low cost film production have large potential applications. - Highlights: • Electrodeposited polyaniline thin films were analyzed in two EGFET setups. • Polymer protonation provided changeable sensitivities. • Color and morphological variation confirm polymer aggregation and electrical changes

  15. From capillary condensation to interface localization transitions in colloid-polymer mixtures confined in thin-film geometry.

    Science.gov (United States)

    De Virgiliis, Andres; Vink, Richard L C; Horbach, Jürgen; Binder, Kurt

    2008-10-01

    Monte Carlo simulations of the Asakura-Oosawa model for colloid-polymer mixtures confined between two parallel repulsive structureless walls are presented and analyzed in the light of current theories on capillary condensation and interface localization transitions. Choosing a polymer-to-colloid size ratio of q=0.8 and studying ultrathin films in the range of D=3 to D=10 colloid diameters thickness, grand canonical Monte Carlo methods are used; phase transitions are analyzed via finite size scaling, as in previous work on bulk systems and under confinement between identical types of walls. Unlike the latter work, inequivalent walls are used here: While the left wall has a hard-core repulsion for both polymers and colloids, at the right-hand wall an additional square-well repulsion of variable strength acting only on the colloids is present. We study how the phase separation into colloid-rich and colloid-poor phases occurring already in the bulk is modified by such a confinement. When the asymmetry of the wall-colloid interaction increases, the character of the transition smoothly changes from capillary condensation type to interface localization type. For very thin films (i.e., for D=3 ) and a suitable choice of the wall-colloid interactions, evidence is found that the critical behavior falls in the universality class of the two-dimensional Ising model. Otherwise, we observe crossover scaling between different universality classes (namely, the crossover from the three-dimensional to the two-dimensional Ising model universality class). The colloid and polymer density profiles across the film in the various phases are discussed, as well as the correlation of interfacial fluctuations in the direction parallel to the confining walls. The broadening of the interface between the coexisting colloid-rich and polymer-rich phases (located parallel to the confining walls) is understood in terms of capillary wave fluctuations. The experimental observability of all these

  16. Utilization of highly purified single wall carbon nanotubes dispersed in polymer thin films for an improved performance of an electrochemical glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Goornavar, Virupaxi [Molecular Toxicology Laboratory, Center for Biotechnology and Biomedical Sciences, Norfolk State University, 700 Park Avenue, Norfolk, VA 23504 (United States); Center for Materials Research, Norfolk State University, 555 Park Avenue, Norfolk, VA 23504 (United States); Jeffers, Robert [Molecular Toxicology Laboratory, Center for Biotechnology and Biomedical Sciences, Norfolk State University, 700 Park Avenue, Norfolk, VA 23504 (United States); Luna Innovations, Inc., 706 Forest St., Suite A, Charlottesville, VA 22902 (United States); Biradar, Santoshkumar [RICE University, 6100 Main St, Houston, TX 77251 (United States); Ramesh, Govindarajan T., E-mail: gtramesh@nsu.edu [Molecular Toxicology Laboratory, Center for Biotechnology and Biomedical Sciences, Norfolk State University, 700 Park Avenue, Norfolk, VA 23504 (United States); Center for Materials Research, Norfolk State University, 555 Park Avenue, Norfolk, VA 23504 (United States)

    2014-07-01

    In this work we report the improved performance an electrochemical glucose sensor based on a glassy carbon electrode (GCE) that has been modified with highly purified single wall carbon nanotubes (SWCNTs) dispersed in polyethyleneimine (PEI), polyethylene glycol (PEG) and polypyrrole (PPy). The single wall carbon nanotubes were purified by both thermal and chemical oxidation to achieve maximum purity of ∼ 98% with no damage to the tubes. The SWCNTs were then dispersed by sonication in three different organic polymers (1.0 mg/ml SWCNT in 1.0 mg/ml of organic polymer). The stable suspension was coated onto the GCE and electrochemical characterization was performed by Cyclic Voltammetry (CV) and Amperometry. The electroactive enzyme glucose oxidase (GOx) was immobilized on the surface of the GCE/(organic polymer–SWCNT) electrode. The amperometric detection of glucose was carried out at 0.7 V versus Ag/AgCl. The GCE/(SWCNT–PEI, PEG, PPY) gave a detection limit of 0.2633 μM, 0.434 μM, and 0.9617 μM, and sensitivities of 0.2411 ± 0.0033 μA mM{sup −1}, r{sup 2} = 0.9984, 0.08164 ± 0.001129 μA mM{sup −1}, r{sup 2} = 0.9975, 0.04189 ± 0.00087 μA mM{sup −1}, and r{sup 2} = 0.9944 respectively and a response time of less than 5 s. The use of purified SWCNTs has several advantages, including fast electron transfer rate and stability in the immobilized enzyme. The significant enhancement of the SWCNT modified electrode as a glucose sensor can be attributed to the superior conductivity and large surface area of the well dispersed purified SWCNTs. - Highlights: • Purification method employed here use cheap and green oxidants. • The method does not disrupt the electronic structure of nanotubes. • This method removes nearly < 2% metallic impurities. • Increases the sensitivity and performance of glassy carbon electrode • This system can detect as low as 0.066 μM of H{sub 2}O{sub 2} and 0.2633 μM of glucose.

  17. Controlled and tunable polymer particles' production using a single microfluidic device

    Science.gov (United States)

    Amoyav, Benzion; Benny, Ofra

    2018-04-01

    Microfluidics technology offers a new platform to control liquids under flow in small volumes. The advantage of using small-scale reactions for droplet generation along with the capacity to control the preparation parameters, making microfluidic chips an attractive technology for optimizing encapsulation formulations. However, one of the drawback in this methodology is the ability to obtain a wide range of droplet sizes, from sub-micron to microns using a single chip design. In fact, typically, droplet chips are used for micron-dimension particles, while nanoparticles' synthesis requires complex chips design (i.e., microreactors and staggered herringbone micromixer). Here, we introduce the development of a highly tunable and controlled encapsulation technique, using two polymer compositions, for generating particles ranging from microns to nano-size using the same simple single microfluidic chip design. Poly(lactic-co-glycolic acid) (PLGA 50:50) or PLGA/polyethylene glycol polymeric particles were prepared with focused-flow chip, yielding monodisperse particle batches. We show that by varying flow rate, solvent, surfactant and polymer composition, we were able to optimize particles' size and decrease polydispersity index, using simple chip designs with no further related adjustments or costs. Utilizing this platform, which offers tight tuning of particle properties, could offer an important tool for formulation development and can potentially pave the way towards a better precision nanomedicine.

  18. UV-transmission and fluorescence properties of polymer thin foils for use in microlens array fabrication

    International Nuclear Information System (INIS)

    Silvano, Donati; Wei, Mao-Kuo; Cai, Jhih-Hao; Lee, Jiun-Haw

    2010-01-01

    There is a report of measurements of optical transmission and fluorescence of thin foils of polyethylene terephthalate polymer, data that are unavailable in literature to the best of our knowledge. The foils are those commonly used as substrate and lens material in microlens arrays designed for use in multi-pixel image photodetectors with the purpose of fill-factor recovery. The wavelength range covered by the measurements is 200 to 800 nm and the thickness of polyethylene terephthalate foils is 40-80 μm. It was found a UV-transmission cutoff of 320 nm for polyethylene terephthalate and 330 nm for cured epoxy on polyethylene terephthalate. Fluorescence of the samples is peaked at 385 nm and the wavelength of most effective fluorescence is 340 nm

  19. Single-electron pulse-height spectra in thin-gap parallel-plate chambers

    CERN Document Server

    Fonte, Paulo J R; Peskov, Vladimir; Policarpo, Armando

    1999-01-01

    Single-electron pulse-height spectra were measured in 0.6 and 1.2 mm parallel-plate chambers developed for the TOF system of the ALICE /LHC-HI experiment. Mixtures of Ar with ethane, isobutane, and SF/sub 6/ were studied. The observed spectrum shows a clear peak for all gases, suggesting efficient single-electron detection in thin parallel-plate structures. The pulse-height spectrum can be described by the weighted sum of an exponential and a Polya distribution, the Polya contribution becoming more important at higher gains. Additionally, it was found that the maximum gain, above 10/sup 6/, is limited by the appearance of streamers and depends weakly on the gas composition. The suitability of each mixture for single-electron detection is also quantitatively assessed. (8 refs).

  20. Ambipolar Small-Molecule:Polymer Blend Semiconductors for Solution-Processable Organic Field-Effect Transistors.

    Science.gov (United States)

    Kang, Minji; Hwang, Hansu; Park, Won-Tae; Khim, Dongyoon; Yeo, Jun-Seok; Kim, Yunseul; Kim, Yeon-Ju; Noh, Yong-Young; Kim, Dong-Yu

    2017-01-25

    We report on the fabrication of an organic thin-film semiconductor formed using a blend solution of soluble ambipolar small molecules and an insulating polymer binder that exhibits vertical phase separation and uniform film formation. The semiconductor thin films are produced in a single step from a mixture containing a small molecular semiconductor, namely, quinoidal biselenophene (QBS), and a binder polymer, namely, poly(2-vinylnaphthalene) (PVN). Organic field-effect transistors (OFETs) based on QBS/PVN blend semiconductor are then assembled using top-gate/bottom-contact device configuration, which achieve almost four times higher mobility than the neat QBS semiconductor. Depth profile via secondary ion mass spectrometry and atomic force microscopy images indicate that the QBS domains in the films made from the blend are evenly distributed with a smooth morphology at the bottom of the PVN layer. Bias stress test and variable-temperature measurements on QBS-based OFETs reveal that the QBS/PVN blend semiconductor remarkably reduces the number of trap sites at the gate dielectric/semiconductor interface and the activation energy in the transistor channel. This work provides a one-step solution processing technique, which makes use of soluble ambipolar small molecules to form a thin-film semiconductor for application in high-performance OFETs.

  1. Single source precursors for fabrication of I-III-VI{sub 2} thin-film solar cells via spray CVD

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, J.A.; Banger, K.K.; Jin, M.H.-C.; Harris, J.D.; Cowen, J.E.; Bohannan, E.W.; Switzer, J.A.; Buhro, W.E.; Hepp, A.F

    2003-05-01

    The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors can be used in either a hot, or cold-wall spray chemical vapour deposition reactor, for depositing CuInS{sub 2}, CuGaS{sub 2} and CuGaInS{sub 2} at reduced temperatures (400-450 sign C), which display good electrical and optical properties suitable for photovoltaic devices. X-ray diffraction studies, energy dispersive spectroscopy and scanning electron microscopy confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures.

  2. Quantifying bacterial adhesion on antifouling polymer brushes via single-cell force spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Janel, S.; de los Santos Pereira, Andres; Bruns, M.; Lafont, F.

    2015-01-01

    Roč. 6, č. 31 (2015), s. 5740-5751 ISSN 1759-9954 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : antifouling polymer brushes * single-cell force spectroscopy * bacterial adhesion Subject RIV: BO - Biophysics Impact factor: 5.687, year: 2015

  3. Giant coercivity in ferromagnetic Co doped ZnO single crystal thin film

    International Nuclear Information System (INIS)

    Loukya, B.; Negi, D.S.; Dileep, K.; Kumar, N.; Ghatak, Jay; Datta, R.

    2013-01-01

    The origin of ferromagnetism in ZnO doped with transition metal impurities has been discussed extensively and appeared to be a highly controversial and challenging topic in today's solid state physics. Magnetism observed in this system is generally weak and soft. We have grown Co:ZnO up to 30 at% Co in single crystal thin film form on c-plane sapphire. A composition dependent coercivity is observed in this system which reaches peak value at 25 at% Co, the values are 860 Oe and 1149 Oe with applied field along parallel and perpendicular to the film substrate interface respectively. This giant coercivity might pave the way to exploit this material as a magnetic semiconductor with novel logic functionalities. The findings are explained based on defect band itinerant ferromagnetism and its partial interaction with localized d electrons of Co through charge transfer. Besides large coercivity, an increase in the band gap with Co concentration has also been observed along with blue emission peak with long tail confirming the formation of extended point defect levels in the host lattice band gap. - Highlights: • Co doped ZnO ferromagnetic single crystal thin film. • Giant coercivity in Co:ZnO thin film which may help to turn this material into application. • Cathodoluminescence (CL) data showing increase in band gap with Co concentrations. • A theoretical proposal is made to explain the observed giant coercivity

  4. Second harmonic generation from corona-poled polymer thin films ...

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... We characterize thermal stability of second harmonic generation (SHG) properties of four different Y-type polymers poled using corona poling method. These polymers are based on donor–acceptor–donor-type repeating unit with different aromatic moieties acting as donors and dicyanomethylene acting as ...

  5. Controlling the scattering properties of thin, particle-doped coatings

    Science.gov (United States)

    Rogers, William; Corbett, Madeleine; Manoharan, Vinothan

    2013-03-01

    Coatings and thin films of small particles suspended in a matrix possess optical properties that are important in several industries from cosmetics and paints to polymer composites. Many of the most interesting applications require coatings that produce several bulk effects simultaneously, but it is often difficult to rationally formulate materials with these desired optical properties. Here, we focus on the specific challenge of designing a thin colloidal film that maximizes both diffuse and total hemispherical transmission. We demonstrate that these bulk optical properties follow a simple scaling with two microscopic length scales: the scattering and transport mean free paths. Using these length scales and Mie scattering calculations, we generate basic design rules that relate scattering at the single particle level to the film's bulk optical properties. These ideas will be useful in the rational design of future optically active coatings.

  6. Synthesis of single phase of CuTl-1234 thin films

    CERN Document Server

    Khan, N A; Ishida, K; Tateai, F; Kojima, T; Terada, N; Ihara, H

    1999-01-01

    Thin films of CuTl-1234 superconductor have been prepared for the first time using an amorphous phase epitaxy method (APE). In this method, an amorphous phase is sputtered from a target of stoichiometric composition CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub x/. Thin films on the SrTiO/sub 3/ substrate after the thallium treatment are biaxially oriented. The XRD reflected a predominant single phase with c-axis 18.7 AA and pole figure measurements of (103) reflections showed a-axis oriented films with Delta phi =0.8 degrees . Resistivity measurements showed T/sub c/=113 K and preliminary J/sub c/ measurements manifested a current density of 1.0*10/sup 6/ A/cm (77 K, 0 T). The composition of films after EDX measurements is Cu /sub 0.3/Tl/sub 0.7/CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub 12-y/. (8 refs).

  7. Structural Ordering of Semiconducting Polymers and Small-Molecules for Organic Electronics

    Science.gov (United States)

    O'Hara, Kathryn Allison

    Semiconducting polymers and small-molecules can be readily incorporated into electronic devices such as organic photovoltaics (OPVs), thermoelectrics (OTEs), organic light emitting diodes (OLEDs), and organic thin film transistors (OTFTs). Organic materials offer the advantage of being processable from solution to form flexible and lightweight thin films. The molecular design, processing, and resulting thin film morphology of semiconducting polymers drastically affect the optical and electronic properties. Charge transport within films of semiconducting polymers relies on the nanoscale organization to ensure electronic coupling through overlap of molecular orbitals and to provide continuous transport pathways. While the angstrom-scale packing details can be studied using X-ray scattering methods, an understanding of the mesoscale, or the length scale over which smaller ordered regions connect, is much harder to achieve. Grain boundaries play an important role in semiconducting polymer thin films where the average grain size is much smaller than the total distance which charges must traverse in order to reach the electrodes in a device. The majority of semiconducting polymers adopt a lamellar packing structure in which the conjugated backbones align in parallel pi-stacks separated by the alkyl side-chains. Only two directions of transport are possible--along the conjugated backbone and in the pi-stacking direction. Currently, the discussion of transport between crystallites is centered around the idea of tie-chains, or "bridging" polymer chains connecting two ordered regions. However, as molecular structures become increasingly complex with the development of new donor-acceptor copolymers, additional forms of connectivity between ordered domains should be considered. High resolution transmission electron microscopy (HRTEM) is a powerful tool for directly imaging the crystalline grain boundaries in polymer and small-molecule thin films. Recently, structures

  8. Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

    International Nuclear Information System (INIS)

    Potthoff, H.H.

    1983-01-01

    Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 μm, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 μm) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations. (author)

  9. Radiation detectors based by polymer materials

    International Nuclear Information System (INIS)

    Cherestes, Margareta; Cherestes, Codrut; Constantinescu, Livia

    2004-01-01

    Scintillation counters make use of the property of certain chemical compounds to emit short light pulses after excitation produced by the passage of charged particles or photons of high energy. These flashes of light are detected by a photomultiplier tube that converts the photons into a voltage pulse. The light emitted from the detector also can be collected, focussed and dispersed by a CCD detector. The study of the evolution of the light emission and of the radiation damage under irradiation is a primary topic in the development of radiation hard polymer based scintillator. Polymer scintillator thin films are used in monitoring radiation beam intensities and simultaneous counting of different radiations. Radiation detectors have characteristics which depend on: the type of radiation, the energy of radiation, and the material of the detector. Three types of polymer thin films were studied: a polyvinyltoluene based scintillator, fluorinated polyimide and PMMA. (authors)

  10. Effects of supercritical carbon dioxide on immobile bound polymer chains on solid substrates

    Science.gov (United States)

    Sen, Mani; Asada, Mitsunori; Jiang, Naisheng; Endoh, Maya K.; Akgun, Bulent; Satija, Sushil; Koga, Tadanori

    2013-03-01

    Adsorbed polymer layers formed on flat solid substrates have recently been the subject of extensive studies because it is postulated to control the dynamics of technologically relevant polymer thin films, for example, in lithography. Such adsorbed layers have been reported to hinder the mobility of polymer chains in thin films even at a large length scale. Consequently, this bound layer remains immobile regardless of processing techniques (i.e. thermal annealing, solvent dissolution, etc). Here, we investigate the use of supercritical carbon dioxide (scCO2) as a novel plasticizer for bound polystyrene layers formed on silicon substrates. In-situ swelling and interdiffusion experiments using neutron reflectivity were performed. As a result, we found the anomalous plasticization effects of scCO2 on the bound polymer layers near the critical point where the anomalous adsorption of CO2 molecules in polymer thin films has been reported previously. Acknowledgement: We acknowledge the financial support from NSF Grant No. CMMI-084626.

  11. How do evaporating thin films evolve? Unravelling phase-separation mechanisms during solvent-based fabrication of polymer blends

    KAUST Repository

    Wodo, Olga; Ganapathysubramanian, Baskar

    2014-01-01

    © 2014 AIP Publishing LLC. Solvent-based fabrication is a flexible and affordable approach to manufacture polymer thin films. The properties of products made from such films can be tailored by the internal organization (morphology) of the films. However, a precise knowledge of morphology evolution leading to the final film structure remains elusive, thus limiting morphology control to a trial and error approach. In particular, understanding when and where phases are formed, and how they evolve would provide rational guidelines for more rigorous control. Here, we identify four modes of phase formation and subsequent propagation within the thinning film during solvent-based fabrication. We unravel the origin and propagation characteristics of each of these modes. Finally, we construct a mode diagram that maps processing conditions with individual modes. The idea introduced here enables choosing processing conditions to tailor film morphology characteristics and paves the ground for a deeper understanding of morphology control with the ultimate goal of precise, yet affordable, morphology manipulation for a large spectrum of applications.

  12. How do evaporating thin films evolve? Unravelling phase-separation mechanisms during solvent-based fabrication of polymer blends

    KAUST Repository

    Wodo, Olga

    2014-10-13

    © 2014 AIP Publishing LLC. Solvent-based fabrication is a flexible and affordable approach to manufacture polymer thin films. The properties of products made from such films can be tailored by the internal organization (morphology) of the films. However, a precise knowledge of morphology evolution leading to the final film structure remains elusive, thus limiting morphology control to a trial and error approach. In particular, understanding when and where phases are formed, and how they evolve would provide rational guidelines for more rigorous control. Here, we identify four modes of phase formation and subsequent propagation within the thinning film during solvent-based fabrication. We unravel the origin and propagation characteristics of each of these modes. Finally, we construct a mode diagram that maps processing conditions with individual modes. The idea introduced here enables choosing processing conditions to tailor film morphology characteristics and paves the ground for a deeper understanding of morphology control with the ultimate goal of precise, yet affordable, morphology manipulation for a large spectrum of applications.

  13. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  14. Self-destruction and dewetting of thin polymer films the role of interfacial tensions

    CERN Document Server

    Reiter, G; Sharma, A

    2003-01-01

    We present real-time optical microscopy observations of the pattern evolution in self-destruction and subsequent dewetting of thin polymer films based on experiments with polydimethylsiloxane films sandwiched between silicon wafers and aqueous surfactant solutions. A clear scenario consisting of four distinct stages has been identified: amplification of surface fluctuations, break-up of the film and formation of holes, growth and coalescence of holes, and droplet formation and ripening. Besides a linear dependence on film viscosity and surface tension, the time tau for film rupture varied significantly with film thickness h (tau approx h sup 5), as expected from theory. While the role of long-range forces is dominant only in the first stage, the later stages are controlled by the combination of interfacial tensions resulting in the contact angle characterizing the three-phase contact line. During the first stage, the characteristic distance of the pattern remains constant, represented by a time-independent wa...

  15. The role of ultra-fast solvent evaporation on the directed self-assembly of block polymer thin films

    Science.gov (United States)

    Drapes, Chloe; Nelson, G.; Grant, M.; Wong, J.; Baruth, A.

    The directed self-assembly of nano-structures in block polymer thin films viasolvent vapor annealing is complicated by several factors, including evaporation rate. Solvent vapor annealing exposes a disordered film to solvent(s) in the vapor phase, increasing mobility and tuning surface energy, with the intention of producing an ordered structure. Recent theoretical predictions reveal the solvent evaporation affects the resultant nano-structuring. In a competition between phase separation and kinetic trapping during drying, faster solvent removal can enhance the propagation of a given morphology into the bulk of the thin film down to the substrate. Recent construction of a purpose-built, computer controlled solvent vapor annealing chamber provides control over forced solvent evaporation down to 15 ms. This is accomplished using pneumatically actuated nitrogen flow into and out of the chamber. Furthermore, in situ spectral reflectance, with 10 ms temporal resolution, monitors the swelling and evaporation. Presently, cylinder-forming polystyrene-block-polylactide thin films were swollen with 40% (by volume) tetrahydrofuran, followed by immediate evaporation under a variety of designed conditions. This includes various evaporation times, ranging from 15 ms to several seconds, and four unique rate trajectories, including linear, exponential, and combinations. Atomic force microscopy reveals specific surface, free and substrate, morphologies of the resultant films, dependent on specific evaporation conditions. Funded by the Clare Boothe Luce Foundation and Nebraska EPSCoR.

  16. Effects of solvent evaporation conditions on solvent vapor annealed cylinder-forming block polymer thin films

    Science.gov (United States)

    Grant, Meagan; Jakubowski, William; Nelson, Gunnar; Drapes, Chloe; Baruth, A.

    Solvent vapor annealing is a less time and energy intensive method compared to thermal annealing, to direct the self-assembly of block polymer thin films. Periodic nanostructures have applications in ultrafiltration, magnetic arrays, or other structures with nanometer dimensions, driving its continued interest. Our goal is to create thin films with hexagonally packed, perpendicular aligned cylinders of poly(lactide) in a poly(styrene) matrix that span the thickness of the film with low anneal times and low defect densities, all with high reproducibility, where the latter is paramount. Through the use of our computer-controlled, pneumatically-actuated, purpose-built solvent vapor annealing chamber, we have the ability to monitor and control vapor pressure, solvent concentration within the film, and solvent evaporation rate with unprecedented precision and reliability. Focusing on evaporation, we report on two previously unexplored areas, chamber pressure during solvent evaporation and the flow rate of purging gas aiding the evaporation. We will report our exhaustive results following atomic force microscopy analysis of films exposed to a wide range of pressures and flow rates. Reliably achieving well-ordered films, while occurring within a large section of this parameter space, was correlated with high-flow evaporation rates and low chamber pressures. These results have significant implications on other methods of solvent annealing, including ``jar'' techniques.

  17. Origins of the helical wrapping of phenyleneethynylene polymers about single-walled carbon nanotubes.

    Science.gov (United States)

    Von Bargen, Christopher D; MacDermaid, Christopher M; Lee, One-Sun; Deria, Pravas; Therien, Michael J; Saven, Jeffery G

    2013-10-24

    The highly charged, conjugated polymer poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) has been shown to wrap single-wall carbon nanotubes (SWNTs), adopting a robust helical superstructure. Surprisingly, PPES adopts a helical rather than a linear conformation when adhered to SWNTs. The complexes formed by PPES and related polymers upon helical wrapping of a SWNT are investigated using atomistic molecular dynamics (MD) simulations in the presence and absence of aqueous solvent. In simulations of the PPES/SWNT system in an aqueous environment, PPES spontaneously takes on a helical conformation. A potential of mean force, ΔA(ξ), is calculated as a function of ξ, the component of the end-to-end vector of the polymer chain projected on the SWNT axis; ξ is a monotonic function of the polymer's helical pitch. ΔA(ξ) provides a means to quantify the relative free energies of helical conformations of the polymer when wrapped about the SWNT. The aqueous system possesses a global minimum in ΔA(ξ) at the experimentally observed value of the helical pitch. The presence of this minimum is associated with preferred side chain conformations, where the side chains adopt conformations that provide van der Waals contact between the tubes and the aliphatic components of the side chains, while exposing the anionic sulfonates for aqueous solvation. The simulations provide a free energy estimate of a 0.2 kcal/mol/monomer preference for the helical over the linear conformation of the PPES/SWNT system in an aqueous environment.

  18. Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template

    KAUST Repository

    Zhu, Jie

    2014-02-12

    Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules. © 2014 American Chemical Society.

  19. Optical response of heterogeneous polymer layers containing silver nanostructures

    Directory of Open Access Journals (Sweden)

    Miriam Carlberg

    2017-05-01

    Full Text Available This work is focused on the study of the optical properties of silver nanostructures embedded in a polymer host matrix. The introduction of silver nanostructures in polymer thin films is assumed to result in layers having adaptable optical properties. Thin film layers with inclusions of differently shaped nanoparticles, such as nanospheres and nanoprisms, and of different sizes, are optically characterized. The nanoparticles are produced by a simple chemical synthesis at room temperature in water. The plasmonic resonance peaks of the different colloidal solutions range from 390 to 1300 nm. The non-absorbing, transparent polymer matrix poly(vinylpyrrolidone (PVP was chosen because of its suitable optical and chemical properties. The optical studies of the layers include spectrophotometry and spectroscopic ellipsometry measurements, which provide information about the reflection, transmission, absorption of the material as well as the complex optical indices, n and k. Finite difference time domain simulations of nanoparticles in thin film layers allow the visualization of the nanoparticle interactions or the electric field enhancement on and around the nanoparticles to complete the optical characterization. A simple analysis method is proposed to obtain the complex refractive index of nanospheres and nanoprisms in a polymer matrix.

  20. New Fabrication Strategies for Polymer Electrolyte Batteries

    National Research Council Canada - National Science Library

    Shriver, D

    1997-01-01

    .... The objective of this research was to fabricate lithium-polymer batteries by techniques that may produce a thin electrolyte and cathode films and with minimal contamination during fabrication. One such technique, ultrasonic spray was used. Another objective of this research was to test lithium cells that incorporate the new polymer electrolytes and polyelectrolytes.

  1. Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors

    KAUST Repository

    Chen, Hu

    2017-07-19

    The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.

  2. Application of electron beam, ion beam and positron beam to polymer sciences

    International Nuclear Information System (INIS)

    Tagawa, Seiichi

    1999-01-01

    Full text: Particle beams are finding increasing application in material sciences and the interest covers both applied as well as fundamental investigations. In the present talk application of electron and ion beams in several polymers such as polysilanes, polystyrene, polyolefins, polymethylmethacrylates and related polymers will be presented. It includes among other investigations (such as product analysis) pulse radiolysis studies and effect of LET on polymers. Importance of positron studies in material sciences especially bulk polymers is well documented. A relatively new technique, namely, positron beam application especially in thin film polymers is a new and emerging areas. The interest ranges from applied aspects as well as fundamental understanding of surfaces and interfaces. The present talk will detail the development of a pulsed positron beam using LINAC at Institute of Scientific and Industrial Research (ISIR) as well as its applications to polymer thin films

  3. Single-Molecule Luminescence and High Efficiency Photovoltaic Cells Based on Percolated Conducting Carbon Nanotubes Scaffolds Templated with Light-Harvesting Conjugated Polymers and Nanohybrids

    National Research Council Canada - National Science Library

    Yang, Arnold C

    2009-01-01

    .... Nanocomposites constructed by surface-grafted multiwall carbon nanotubes (CNTs) with conjugated polymers dispersed in a polymer matrix were synthesized to form novel optoelectronic materials that exploit single-molecule effects...

  4. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    KAUST Repository

    Jiwuer, Jilili

    2014-07-07

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

  5. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    KAUST Repository

    Jiwuer, Jilili; Abdurahman, Ayjamal; Gü lseren, Oğuz; Schwingenschlö gl, Udo

    2014-01-01

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

  6. Direct Photopatterning of Electrochromic Polymers

    DEFF Research Database (Denmark)

    Jensen, Jacob; Dyer, Aubrey L.; Shen, D. Eric

    2013-01-01

    Propylenedioxythiophene (ProDOT) polymers are synthesized using an oxidative polymerization route that results in methacrylate substituted poly(ProDOTs) having a Mn of 10–20 kDa wherein the methacrylate functionality constitutes from 6 to 60% of the total monomer units. Solutions of these polymers...... show excellent film forming abilities, with thin films prepared using both spray‐casting and spin‐coating. These polymers are demonstrated to crosslink upon UV irradiation at 350 nm, in the presence of an appropriate photoinitiator, to render the films insoluble to common organic solvents....... Electrochemical, spectroelectrochemical, and colorimetric analyses of the crosslinked polymer films are performed to establish that they retain the same electrochromic qualities as the parent polymers with no detriment to the observed properties. To demonstrate applicability for multi‐film processing...

  7. Angular dependencies of longitudinal magnetoresistivity and planar Hall effect of single and multilayered thin films

    International Nuclear Information System (INIS)

    Ko, T.W.; Lee, J.H.; Park, B.K.; Rhie, K.; Jang, P.W.; Hwang, D.G.; Lee, S.S.; Kim, M.Y.; Rhee, J.R.

    1998-01-01

    Magnetoresistivity and planar Hall effect of a Glass/Fe70A/[Co21A/Cu25A] 20 multilayer coupled antiferromagnetically a single layer (Co81Nb19) thin film, and NiO based Glass/Ni350A/Py50A/Cu20A/Py50A (Py = Ni 83 Fe 17 ) spin value are studied. Planar Hall resistivity is analysed concurrently with the resistivity of the sample. With variation of direction and strength of the applied fields, we found that the magnetization process affects significantly the planar Hall effect. We developed a simple method to find the easy axis of single layer magnetic thin films. We also observed the variation of magnetization of each layer separately for an antiferromagnetically coupled multilayer, and a NiO-based spin value with the planar Hall effect. (author)

  8. All-in-polymer injection molded device for single cell capture using multilevel silicon master fabrication

    DEFF Research Database (Denmark)

    Tanzi, S.; Larsen, S.T.; Matteucci, M.

    2012-01-01

    This work demonstrates a novel all-in-polymer device for single cell capture applicable for biological recordings. The chip is injection molded and comprises a "cornered" (non planar) aperture. It has been demonstrated how cornered apertures are straightforward to mold in PDMS [1,2]. In this stud...

  9. Confining multiple polymers between sticky walls: a directed walk model of two polymers

    International Nuclear Information System (INIS)

    Wong, Thomas; Rechnitzer, Andrew; Owczarek, Aleksander L

    2014-01-01

    We study a model of two polymers confined to a slit with sticky walls. More precisely, we find and analyse the exact solution of two directed friendly walks in such a geometry on the square lattice. We compare the infinite slit limit, in which the length of the polymer (thermodynamic limit) is taken to infinity before the width of the slit is considered to become large, to the opposite situation where the order of the limits are swapped, known as the half-plane limit when one polymer is modelled. In contrast with the single polymer system we find that the half-plane and infinite slit limits coincide. We understand this result in part due to the tethering of polymers on both walls of the slit. We also analyse the entropic force exerted by the polymers on the walls of the slit. Again the results differ significantly from single polymer models. In a single polymer system both attractive and repulsive regimes were seen, whereas in our two walk model only repulsive forces are observed. We do, however, see that the range of the repulsive force is dependent on the parameter values. This variation can be explained by the adsorption of the walks on opposite walls of the slit. (paper)

  10. Polymer Electrolytes

    Science.gov (United States)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  11. Feasibility of X-ray analysis of multi-layer thin films at a single beam voltage

    International Nuclear Information System (INIS)

    Statham, P J

    2010-01-01

    Multi-layer analysis using electron beam excitation and X-ray spectrometry is a powerful tool for characterising layers down to 1 nm thickness and with typically 1 μm lateral resolution but does not always work. Most published applications have used WDS with many measurements at different beam voltages and considerable experience has been needed to choose lines and voltages particularly for complex multi-layer problems. A new objective mathematical approach is described which demonstrates whether X-ray analysis can obtain reliable results for an arbitrary multi-layer problem. A new algorithm embodied in 'ThinFilmID' software produces a single plot that shows feasibility of achieving results with a single EDS spectrum and suggests the optimal beam voltage. Synthesis of EDS spectra allows the precision in results to be estimated and acquisition conditions modified before wasting valuable instrument time. Thus, practicality of multi-layer thin film analysis at a single beam voltage can now be established without the extensive experimentation that was previously required by a microanalysis expert. Examples are shown where the algorithm discovers viable single-voltage conditions for applications that experts previously thought could only be addressed using measurements at more than one beam voltage.

  12. Molecular Weight Effects on the Glass Transition and Confinement Behavior of Polymer Thin Films.

    Science.gov (United States)

    Xia, Wenjie; Hsu, David D; Keten, Sinan

    2015-08-01

    Nanoscale polymer thin films exhibit strong confinement effects on Tg arising from free surfaces. However, the coupled influence of molecular weight (MW) and surface effects on Tg is not well understood for low MW film systems below the entanglement length. Utilizing atomistically informed coarse-grained molecular dynamics simulations for poly(methyl methacrylate) (PMMA), it is demonstrated that the decrease in free-standing film Tg with respect to bulk is more significant for low MW compared to high MW systems. Investigation of the local interfacial properties reveals that the increase in the local free volume near the free surface is greater for low MW, explaining the MW dependence of Tg -confinement behaviors. These findings corroborate recent experiments on low MW films, and highlight the relationship between nanoconfinement phenomena and local free volume effects arising from free surfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Thin films as an emerging platform for drug delivery

    Directory of Open Access Journals (Sweden)

    Sandeep Karki

    2016-10-01

    Full Text Available Pharmaceutical scientists throughout the world are trying to explore thin films as a novel drug delivery tool. Thin films have been identified as an alternative approach to conventional dosage forms. The thin films are considered to be convenient to swallow, self-administrable, and fast dissolving dosage form, all of which make it as a versatile platform for drug delivery. This delivery system has been used for both systemic and local action via several routes such as oral, buccal, sublingual, ocular, and transdermal routes. The design of efficient thin films requires a comprehensive knowledge of the pharmacological and pharmaceutical properties of drugs and polymers along with an appropriate selection of manufacturing processes. Therefore, the aim of this review is to provide an overview of the critical factors affecting the formulation of thin films, including the physico-chemical properties of polymers and drugs, anatomical and physiological constraints, as well as the characterization methods and quality specifications to circumvent the difficulties associated with formulation design. It also highlights the recent trends and perspectives to develop thin film products by various companies.

  14. Growth of long triisopropylsilylethynyl pentacene (TIPS-PEN) nanofibrils in a polymer thin film during spin-coating.

    Science.gov (United States)

    Park, Minwoo; Min, Yuho; Lee, Yu-Jeong; Jeong, Unyong

    2014-03-01

    This study demonstrates the growth of long triisopropylsilyethynyl pentacene (TIPS-PEN) nanofibrils in a thin film of a crystalline polymer, poly(ε-caprolactone) (PCL). During spin-coating, TIPS-PEN molecules are locally extracted around the PCL grain boundaries and they crystallize into [010] direction forming long nanofibrils. Molecular weight of PCL and weight fraction (α) of TIPS-PEN in PCL matrix are key factors to the growth of nanofibrils. Long high-quality TIPS-PEN nanofibrils are obtained with high-molecular-weight PCL and at the α values in the range of 0.03-0.1. The long nanofibrils are used as an active layer in a field-effect organic transistor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Claisen thermally rearranged (CTR) polymers

    Science.gov (United States)

    Tena, Alberto; Rangou, Sofia; Shishatskiy, Sergey; Filiz, Volkan; Abetz, Volker

    2016-01-01

    Thermally rearranged (TR) polymers, which are considered the next-generation of membrane materials because of their excellent transport properties and high thermal and chemical stability, are proven to have significant drawbacks because of the high temperature required for the rearrangement and low degree of conversion during this process. We demonstrate that using a [3,3]-sigmatropic rearrangement, the temperature required for the rearrangement of a solid glassy polymer was reduced by 200°C. Conversions of functionalized polyimide to polybenzoxazole of more than 97% were achieved. These highly mechanically stable polymers were almost five times more permeable and had more than two times higher degrees of conversion than the reference polymer treated under the same conditions. Properties of these second-generation TR polymers provide the possibility of preparing efficient polymer membranes in a form of, for example, thin-film composite membranes for various gas and liquid membrane separation applications. PMID:27482538

  16. Finite strain analyses of deformations in polymer specimens

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2016-01-01

    Analyses of the stress and strain state in test specimens or structural components made of polymer are discussed. This includes the Izod impact test, based on full 3D transient analyses. Also a long thin polymer tube under internal pressure has been studied, where instabilities develop, such as b...

  17. Biomaterial thin film deposition and characterization by means of MAPLE technique

    International Nuclear Information System (INIS)

    Bloisi, F.; Vicari, L.; Papa, R.; Califano, V.; Pedrazzani, R.; Bontempi, E.; Depero, L.E.

    2007-01-01

    Polyethylene glycol (PEG) is a polymer with technologically important applications, especially as a biomaterial. Several biomedical applications (such as tissue engineering, spatial patterning of cells, anti-biofouling and biocompatible coatings) require the application of high quality PEG thin films. In order to have a good adhesion to substrate chemically modified polymer molecules have been used, but for some 'in vivo' applications it is essential to deposit a film with the same chemical and structural properties of bulk PEG. Pulsed laser deposition (PLD) technique is generally able to produce high quality thin films but it is inadequate for polymer/organic molecules. MAPLE (Matrix Assisted Pulsed Laser Evaporation) is a recently developed PLD based thin film deposition technique, particularly well suited for organic/polymer thin film deposition. Up to now MAPLE depositions have been carried out mainly by means of modified PLD systems, using excimer lasers operating in UV, but the use of less energetic radiations can minimize the photochemical decomposition of the polymer molecules. We have used a deposition system explicitly designed for MAPLE technique connected to a Q-switched Ng:YAG pulsed laser which can be operated at different wavelength ranging from IR to UV in order to optimise the deposition parameters. The capability of MAPLE technique to deposit PEG has been confirmed and preliminary results show that visible (532 nm wavelength) radiation gives better results with respect to UV (355 nm) radiation. Despite usually UV wavelengths have been used and even if more systematic tests must be performed, it is important to underline that the choice of laser wavelength plays an important role in the application of MAPLE thin film deposition technique

  18. Microfluidic Fabrication of Porous Polymer Microspheres: Dual Reactions in Single Droplets

    KAUST Repository

    Gong, Xiuqing

    2009-06-16

    We report the microfluidic fabrication of macroporous polymer microspheres via the simultaneous reactions within single droplets, induced by LTV irradiation. The aqueous phase of the reaction is the decomposition of H 2O2 to yield oxygen, whereas the organic phase is the polymerization of NO A 61, ethylene glycol dimethacrylate (EGDMA), and tri (propylene glycol) diacrylate (TPGDA) precursors. We first used a liquid polymer precursor to encapsulate a multiple number of magnetic Fe3O 4 colloidal suspension (MCS) droplets in a core-shell structure, for the purpose of studying the number of such encapsulated droplets that can be reliably controlled through the variation of flow rates. It was found that the formation of one shell with one, two, three, or more encapsulated droplets is possible. Subsequently, the H2O2 solution was encapsulated in the same way, after which we investigated its decomposition under UV irradiation, which simultaneously induces the polymerization of the encapsulating shell. Because the H2O2 decomposition leads to the release of oxygen, porous microspheres were obtained from a combined H2O2 decomposition/polymer precursor polymerization reaction. The multiplicity of the initially encapsulated H2O 2 droplets ensures the homogeneous distribution of the pores. The pores inside the micrometer-sized spheres range from several micrometers to tens of micrometers, and the maximum internal void volume fraction can attain 70%, similar to that of high polymerized high internal phase emulsion (polyHIPE). © 2009 American Chemical Society.

  19. Thiophene fused azacoronenes: regioselective synthesis, self organization, charge transport, and its incorporation in conjugated polymers

    Science.gov (United States)

    Liu, Yi; He, Bo

    2015-09-15

    A regioselective synthesis of an azacoronene fused with two peripheral thiophene groups has been realized through a concise synthetic route. The resulting thienoazacoronene (TAC) derivatives show high degree of self-organization in solution, in single crystals, in the bulk, and in spuncast thin films. Spuncast thin film field-effect transistors of the TACs exhibited mobilities up to 0.028 cm.sup.2V.sup.-1 S.sup.-1, which is among the top field effect mobilities for solution processed discotic materials. Organic photovoltaic devices using TAC-containing conjugated polymers as the donor material exhibited a high open-circuit voltage of 0.89 V, which was ascribable to TAC's low-lying highest occupied molecular orbital energy level.

  20. Extrinsic optical-fiber ultrasound sensor using a thin polymer film as a low-finesse Fabry-Perot interferometer

    Science.gov (United States)

    Beard, P. C.; Mills, T. N.

    1996-02-01

    Theoretical and experimental aspects of an extrinsic optical-fiber ultrasound sensor are described. The sensor is based on a thin transparent polymer film acting as a low-finesse Fabry-Perot cavity that is mounted at the end of a multimode optical fiber. Performance was found to be comparable with that of a piezoelectric polyvinylidene difluoride-membrane (PVDF) hydrophone with a sensitivity of 61 mV/MPa, an acoustic noise floor of 2.3 KPa over a 25-MHz bandwidth, and a frequency response to 25 MHz. The wideband-sensitive response and design flexibility of the concept suggests that it may find application as an alternative to piezoelectric devices for the detection and measurement of ultrasound.

  1. A new microcavity design for single molecule detection

    International Nuclear Information System (INIS)

    Steiner, M.; Schleifenbaum, F.; Stupperich, C.; Failla, A.V.; Hartschuh, A.; Meixner, A.J.

    2006-01-01

    We present a new microcavity design which allows for efficient detection of single molecules by measuring the molecular fluorescence emission coupled into a resonant cavity mode. The Fabry-Perot-type microresonator consists of two silver mirrors separated by a thin polymer film doped with dye molecules in ultralow concenctration. By slightly tilting one of the mirrors different cavity lengths can be selected within the same sample. Locally, on a μm scale, the microcavity still acts as a planar Fabry-Perot resonator. Using scanning confocal fluorescence microscopy, single emitters on resonance with a single mode of the microresonator can be spatially addressed. Our microcavity is demonstrated to be well-suited for investigating the coupling mechanism between single quantum emitters and single modes of the electromagnetic field. The microcavity layout could be integrated in a lab-on-a-microchip design for ultrasensitive microfluidic analytics and can be considered as an important improvement for single photon sources based on single molecules operating at room temperature

  2. Optical characterization of epitaxial single crystal CdTe thin films on Al{sub 2}O{sub 3} (0001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, S.M.; Devenyi, G.A., E-mail: devenyga@mcmaster.ca; Jarvis, V.M.; Meinander, K.; Haapamaki, C.M.; Kuyanov, P.; Gerber, M.; LaPierre, R.R.; Preston, J.S.

    2014-11-03

    The optoelectronic properties of single crystal CdTe thin films were investigated by photoluminescence spectroscopy, photoreflectance spectroscopy and variable angle spectroscopic ellipsometry. The room temperature bandgap was measured to be 1.51 eV and was consistent between spectroscopic measurements and previously reported values. Breadth of bandgap emission was consistent with high quality material. Low temperature photoluminescence spectra indicated a dominant emission consistent with bound excitons. Emissions corresponding to self-compensation defects, doping and contaminants were not found. Variable angle spectroscopic ellipsometry measurements over the near-UV to infrared range demonstrated sharp resonance peaks. All spectroscopic measurements indicate high quality thin film material of comparable or better quality than bulk CdTe. - Highlights: • High quality epitaxial CdTe thin films were grown. • Two dimensional X-ray diffraction characterization confirmed single crystal material. • Photoluminescence indicated low defect density when compared to bulk single crystals. • Optical characterization indicated the presence of room temperature excitons.

  3. Inflation of polymer melts into elliptic and circular cylinders

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Christensen, Jens Horslund; Gøttsche, Søren

    2000-01-01

    A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top of the infla......A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top...

  4. Super-resolution fluorescence imaging of nanoimprinted polymer patterns by selective fluorophore adsorption combined with redox switching

    KAUST Repository

    Yabiku, Y.

    2013-10-22

    We applied a super-resolution fluorescence imaging based on selective adsorption and redox switching of the fluorescent dye molecules for studying polymer nanostructures. We demonstrate that nano-scale structures of polymer thin films can be visualized with the image resolution better than 80 nm. The method was applied to image 100 nm-wide polymer nanopatterns fabricated by thermal nanoimprinting. The results point to the applicability of the method for evaluating residual polymer thin films and dewetting defect of the polymer resist patterns which are important for the quality control of the fine nanoimprinted patterns. 2013 Author(s).

  5. Super-resolution fluorescence imaging of nanoimprinted polymer patterns by selective fluorophore adsorption combined with redox switching

    Directory of Open Access Journals (Sweden)

    Yu Yabiku

    2013-10-01

    Full Text Available We applied a super-resolution fluorescence imaging based on selective adsorption and redox switching of the fluorescent dye molecules for studying polymer nanostructures. We demonstrate that nano-scale structures of polymer thin films can be visualized with the image resolution better than 80 nm. The method was applied to image 100 nm-wide polymer nanopatterns fabricated by thermal nanoimprinting. The results point to the applicability of the method for evaluating residual polymer thin films and dewetting defect of the polymer resist patterns which are important for the quality control of the fine nanoimprinted patterns.

  6. Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage.

    Science.gov (United States)

    Nasr, Noha; Elbeshbishy, Elsayed; Hafez, Hisham; Nakhla, George; El Naggar, M Hesham

    2012-05-01

    A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Damage Mechanisms In Polymers Upon NIR Femtosecond Pulse Laser Irradiation: Sub-Threshold Processes And Their Implications For Laser Safety Applications

    International Nuclear Information System (INIS)

    Bonse, Joern; Krueger, Joerg; Solis, Javier; Spielmann, Christian; Lippert, Thomas

    2010-01-01

    This contribution investigates laser-induced damage of thin film and bulk polymer samples, with the focus on physical processes occurring close to the damage threshold. In-situ real-time reflectivity (RTR) measurements with picosecond (ps) and nanosecond (ns) temporal resolution were performed on thin polymer films on a timescale up to a few microseconds (μs). A model for polymer thin film damage is presented, indicating that irreversible chemical modification processes take place already below the fluence threshold for macroscopic damage. On dye-doped bulk polymer filters (as used for laser goggles), transmission studies using fs-and ps-laser pulses reveal the optical saturation behavior of the material and its relation to the threshold of permanent damage. Implications of the sub-threshold processes for laser safety applications will be discussed for thin film and bulk polymer damage.

  8. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio

    2016-01-01

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber...... preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed...... SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured...

  9. Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

    Energy Technology Data Exchange (ETDEWEB)

    Capan, I., E-mail: inci.capan@gmail.com [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Tarimci, C., E-mail: Celik.Tarimci@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Ankara (Turkey); Erdogan, M., E-mail: merdogan@balikesir.edu.tr [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Hassan, A.K., E-mail: A.Hassan@shu.ac.uk [Materials and Engineering Research Institute, Sheffield Hallam University, Sheaf Building, Pond Street, Sheffield S1 1WB (United Kingdom)

    2009-05-05

    In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

  10. Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

    International Nuclear Information System (INIS)

    Capan, I.; Tarimci, C.; Erdogan, M.; Hassan, A.K.

    2009-01-01

    In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

  11. Effects of topology on the adsorption of singly tethered ring polymers to attractive surfaces.

    Science.gov (United States)

    Li, Bing; Sun, Zhao-Yan; An, Li-Jia

    2015-07-14

    We investigate the effect of topology on the equilibrium behavior of singly tethered ring polymers adsorbed on an attractive surface. We focus on the change of square radius of gyration Rg(2), the perpendicular component Rg⊥(2) and the parallel component Rg‖(2) to the adsorbing surface, the mean contacting number of monomers with the surface , and the monomer distribution along z-direction during transition from desorption to adsorption. We find that both of the critical point of adsorption εc and the crossover exponent ϕ depend on the knot type when the chain length of ring ranges from 48 to 400. The behaviors of Rg(2), Rg⊥(2), and Rg‖(2) are found to be dependent on the topology and the monomer-surface attractive strength. At weak adsorption, the polymer chains with more complex topology are more adsorbable than those with simple topology. However, at strong adsorption, the polymer chains with complex topology are less adsorbable. By analyzing the distribution of monomer along z-direction, we give a possible mechanism for the effect of topology on the adsorption behavior.

  12. Nobel Prize 2000: from conducting polymers to molecular electronics

    International Nuclear Information System (INIS)

    Pron, A.; Rannou, P.

    2001-01-01

    In this paper the development of conducting organic polymers is reviewed. Poly(3-alkylthiophenes) with regioregularity exceeding 99% are especially interesting because if used as a thin semiconducting layer in the field effect transistor (FET) configuration they become superconducting at 2.35 K. This is the first example of the superconductivity of an organic polymer. Fields of use of conducting polymers are reviewed, too

  13. Possible stretched exponential parametrization for humidity absorption in polymers.

    Science.gov (United States)

    Hacinliyan, A; Skarlatos, Y; Sahin, G; Atak, K; Aybar, O O

    2009-04-01

    Polymer thin films have irregular transient current characteristics under constant voltage. In hydrophilic and hydrophobic polymers, the irregularity is also known to depend on the humidity absorbed by the polymer sample. Different stretched exponential models are studied and it is shown that the absorption of humidity as a function of time can be adequately modelled by a class of these stretched exponential absorption models.

  14. Controlled bending and folding of a bilayer structure consisting of a thin stiff film and a heat shrinkable polymer sheet

    Science.gov (United States)

    Cui, Jianxun; Adams, John G. M.; Zhu, Yong

    2018-05-01

    Bending pre-designed flat sheets into three-dimensional (3D) structures is attracting much interest, as it provides a simple approach to make 3D devices. Here we report controlled bending and folding of a bilayer structure consisting of a heat shrinkable polymer sheet and a thin stiff film (not thermally responsive). Upon heating, the prestrained polymer sheet shrinks, leading to bending or folding of the bilayer. We studied the effect of relative dimensions of the two layers on the bending behavior and demonstrated the transition from longitudinal bending to transverse bending of the bilayer strip. Transverse bending was utilized to fold origami structures, including several flat letters, a crane, and a corrugated metal sheet via Miura-ori folding. We developed a method to further control the bending orientation based on bio-inspired anisotropic bending stiffness. By bending the metal foil in different orientations, several structures were obtained, including cylindrical surfaces and left-handed/right-handed helical structures.

  15. Atomic force microscopy imaging and 3-D reconstructions of serial thin sections of a single cell and its interior structures

    International Nuclear Information System (INIS)

    Chen Yong; Cai Jiye; Zhao Tao; Wang Chenxi; Dong Shuo; Luo Shuqian; Chen, Zheng W.

    2005-01-01

    The thin sectioning has been widely applied in electron microscopy (EM), and successfully used for an in situ observation of inner ultrastructure of cells. This powerful technique has recently been extended to the research field of atomic force microscopy (AFM). However, there have been no reports describing AFM imaging of serial thin sections and three-dimensional (3-D) reconstruction of cells and their inner structures. In the present study, we used AFM to scan serial thin sections approximately 60 nm thick of a mouse embryonic stem (ES) cell, and to observe the in situ inner ultrastructure including cell membrane, cytoplasm, mitochondria, nucleus membrane, and linear chromatin. The high-magnification AFM imaging of single mitochondria clearly demonstrated the outer membrane, inner boundary membrane and cristal membrane of mitochondria in the cellular compartment. Importantly, AFM imaging on six serial thin sections of a single mouse ES cell showed that mitochondria underwent sequential changes in the number, morphology and distribution. These nanoscale images allowed us to perform 3-D surface reconstruction of interested interior structures in cells. Based on the serial in situ images, 3-D models of morphological characteristics, numbers and distributions of interior structures of the single ES cells were validated and reconstructed. Our results suggest that the combined AFM and serial-thin-section technique is useful for the nanoscale imaging and 3-D reconstruction of single cells and their inner structures. This technique may facilitate studies of proliferating and differentiating stages of stem cells or somatic cells at a nanoscale

  16. VUV Processing of Polymers: Surface Modification and Deposition of Organic Thin Films

    International Nuclear Information System (INIS)

    Wertheimer, M.R.

    2006-01-01

    Materials processing based on the use of vacuum-ultraviolet (VUV) radiation has evolved from the status of 'laboratory curiosum' to that of technological reality, thanks to the availability of commercial light sources, first lasers but more recently VUV-lamps. We begin with a brief survey of application areas, still mostly 'high-tech' on account of the relatively elevated cost of the light sources. In this laboratory, we use a series of commercial VUV lamps (based on radio-frequency discharges in ampoules that are sealed with VUV-transparent MgF 2 ) that cover a broad spectral range, 120 nm 3 ) gas. This allowed us to achieve maximum bound N concentrations, [N] ∼ 25 at%, comparable to values achieved by plasma-induced nitriding. More recently, we have investigated the deposition of polymer-like ( V UV-polymer ) coatings by VUV-induced gas-phase photo-chemistry of ammonia-hydrocarbon mixtures, both gases that strongly absorb VUV photons. We use the same cylindrical high-vacuum reactor, with a VUV lamp and a VUV-sensitive photodiode detector at opposite ends; after measuring radiation intensity, the latter is replaced by a substrate holder, the frontal distance of which (with respect to the lamp) can be adjusted. For 'VUV-polymerization' experiments we have used two resonant lamps (low-pressure Kr and Xe), having 'monochromatic' emissions at λ 123.6 nm and 147.0 nm, respectively. The ammonia-hydrocarbon feed gas mixtures are characterised by their flow rate ratio, R ≡ NH 3 /C x H y , where C x H y designates methane (CH 4 ) or ethylene (C 2 H 4 ), the two 'monomers' investigated so far. Thin 'VUV-polymer' deposits were collected on MgF 2 or Si wafers placed on the substrate holder, and they were examined by a variety of physico-chemical techniques; for example, chemical structure and composition were characterized by X-ray photoelectron spectroscopy (XPS); layer thickness and refractive index, n, were determined by UV-VIS spectro-ellipsometry, and

  17. Determination of the optical constants of polymer light-emitting diode films from single reflection measurements

    International Nuclear Information System (INIS)

    Zhu Dexi; Shen Weidong; Ye Hui; Liu Xu; Zhen Hongyu

    2008-01-01

    We present a simple and fast method to determine the optical constant and physical thickness of polymer films from a single reflectivity measurement. A self-consistent dispersion formula of the Forouhi-Bloomer model was introduced to fit the measured spectral curves by a modified 'Downhill' simplex algorithm. Four widely used polymer light-emitting diodes materials: poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene], poly(9,9-dioctylfluoreny-2,7-diyl) (PFO), poly(N-vinyl carbazole) and poly(3,4-ethylene dioxythiophene) : poly(styrenesulfonate) were investigated by this technique. The refractive indices over the whole visible region as well as the optical band gap extracted by this method agree well with those reported in the literature. The determined physical thicknesses present a deviation less than 4% compared with the experimental values measured by the stylus profiler. The influence of scattering loss on the fitted results is discussed to demonstrate the applicability of this technology for polymer films.

  18. Single-molecule imaging reveals topological isomer-dependent diffusion by 4-armed star and dicyclic 8-shaped polymers

    KAUST Repository

    Habuchi, Satoshi; Fujiwara, Susumu; Yamamoto, Takuya; Tezuka, Yasuyuki

    2015-01-01

    Diffusion dynamics of topological isomers of polymer molecules was investigated at the single-molecule level in a melt state by employing the fluorophore-incorporated 4-armed star and the corresponding doubly-cyclized, 8-shaped poly(THF) chains

  19. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Dutta, P.; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V.; Zheng, N.; Ahrenkiel, P.; Martinez, J.

    2014-01-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10 7  cm −2 . Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm 2 /V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  20. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  1. Dependence of crystallite formation and preferential backbone orientations on the side chain pattern in PBDTTPD polymers

    KAUST Repository

    El Labban, Abdulrahman

    2014-11-26

    (Figure Presented) Alkyl substituents appended to the π-conjugated main chain account for the solution-processability and film-forming properties of most π-conjugated polymers for organic electronic device applications, including field-effect transistors (FETs) and bulk-heterojunction (BHJ) solar cells. Beyond film-forming properties, recent work has emphasized the determining role that side-chain substituents play on polymer self-assembly and thin-film nanostructural order, and, in turn, on device performance. However, the factors that determine polymer crystallite orientation in thin-films, implying preferential backbone orientation relative to the device substrate, are a matter of some debate, and these structural changes remain difficult to anticipate. In this report, we show how systematic changes in the side-chain pattern of poly(benzo[1,2-b:4,5-b′]dithiophene-alt-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers can (i) influence the propensity of the polymer to order in the π-stacking direction, and (ii) direct the preferential orientation of the polymer crystallites in thin films (e.g., "face-on" vs "edge-on"). Oriented crystallites, specifically crystallites that are well-ordered in the π-stacking direction, are believed to be a key contributor to improved thin-film device performance in both FETs and BHJ solar cells.

  2. Field emission mechanism from a single-layer ultra-thin semiconductor film cathode

    International Nuclear Information System (INIS)

    Duan Zhiqiang; Wang Ruzhi; Yuan Ruiyang; Yang Wei; Wang Bo; Yan Hui

    2007-01-01

    Field emission (FE) from a single-layer ultra-thin semiconductor film cathode (SUSC) on a metal substrate has been investigated theoretically. The self-consistent quantum FE model is developed by synthetically considering the energy band bending and electron scattering. As a typical example, we calculate the FE properties of ultra-thin AlN film with an adjustable film thickness from 1 to 10 nm. The calculated results show that the FE characteristic is evidently modulated by varying the film thickness, and there is an optimum thickness of about 3 nm. Furthermore, a four-step FE mechanism is suggested such that the distinct FE current of a SUSC is rooted in the thickness sensitivity of its quantum structure, and the optimum FE properties of the SUSC should be attributed to the change in the effective potential combined with the attenuation of electron scattering

  3. A novel model of photothermal diffusion (PTD) for polymer nano-composite semiconducting of thin circular plate

    Science.gov (United States)

    Lotfy, Kh.

    2018-05-01

    In this article, theoretical discussions for a novel mathematical-physical Photothermal diffusion (PTD) model in the generalized thermoelasticity theory with photothermal processes and chemical action are introduced. The mean idea of this model depends on the interaction between quasi-particles (plasma waves) that depends on the kind of the used materials, the mechanical forces acting on the surface, the generalized thermo and mass diffusion (due to coupling of temperature fields with thermal waves and chemical potential) and the elastic waves. The one dimensional Laplace transforms is used to obtain the exact solution for some physical and chemical quantities for a thin circular plate of a semiconducting polymer nanocomposite such as silicon (Si). New variables are deduced and discussed. The obtained results of the physical quantities are presented analytically and illustrated graphically with some important applications.

  4. Oriented thin films of mixture of a low-bandgap polymer and a fullerene derivative prepared by friction-transfer method

    Science.gov (United States)

    Tanigaki, Nobutaka; Mizokuro, Toshiko; Miyadera, Tetsuhiko; Shibata, Yousei; Koganezawa, Tomoyuki

    2018-02-01

    We have been studying oriented thin films of polymers fabricated by the friction-transfer method, which allows the alignment of a variety of conjugated polymers into highly oriented films. In this study, we prepared oriented blend films of a mixture of a low-bandgap polymer, poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7), and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), which is a promising combination for application in organic solar cells. We obtained oriented blend films of PTB7 and PC71BM by the friction-transfer method from a solid block. Polarized UV-visible spectra show that the PTB7 chains were aligned parallel to the friction direction in the blend films. Grazing-incidence X-ray diffraction (GIXD) studies with synchrotron radiation suggested that the preferred orientation of PTB7 crystallites was face-on in the blend films. The GIXD results also showed the high uniaxial orientation of PTB7 chains in blend films. Photovoltaic devices were fabricated using the friction-transferred blend films of the PTB7 and PC71BM. These bulk heterojunction devices showed better performance than planar heterojunction devices fabricated using pure friction-transferred PTB7 films.

  5. Preparation and thermo-optical characteristics of a smart polymer-stabilized liquid crystal thin film based on smectic A–chiral nematic phase transition

    International Nuclear Information System (INIS)

    Sun, Jian; Wang, Huihui; Cao, Hui; Ding, Hangjun; Yang, Zhou; Yang, Huai; Wang, Ling; Xie, Hui; Luo, Xueyao; Xiao, Jiumei

    2014-01-01

    A smart polymer stabilized liquid crystal (PSLC) thin film with temperature-controllable light transmittance was prepared based on a smectic-A (SmA)–chiral nematic (N*) phase transition, and then the effect of the composition and the preparation condition of the PSLC film on its thermo-optical (T-O) characteristics has been investigated in detail. Within the temperature range of the SmA phase, the PSLC shows a strong opaque state due to the focal conic alignment of liquid crystal (LC) molecules, while the film exhibits a transparent state result from the parallel alignment of N* phase LC molecules at a higher temperature. Importantly, the PSLC films with different temperature of phase transition and contrast ratio can be prepared by changing the composition of photo-polymerizable monomer/LC/chiral dopant. According to the competition between the polymerization of the curable monomers and the diffusion of LC molecules, the ultraviolet (UV) curing surrounding temperature and the intensity of UV irradiation play a critical role in tuning the size of the polymer network meshes, which in turn influence the contrast ratio and the switching speed of the film. Our observations are expected to pave the way for preparing smart PSLC thin films for applications in areas of smart windows, thermo-detectors and other information recording devices. (paper)

  6. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo; Car, Anja; Wind, Jan; Peinemann, Klaus Viktor

    2010-01-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform

  7. Swellipsometry in Twente : Measuring Polymer Swelling by In-Situ Ellipsometry

    NARCIS (Netherlands)

    Ogieglo, Wojciech; Kappert, Emiel J.; Raaijmakers, Michiel; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck E.

    2014-01-01

    Thin and ultra-thin (<100 nm) polymer films are frequently used in important technological areas, including coatings, barrier and membrane applications. In these areas the films are frequently exposed to interacting penetrants. The interactions may significantly change equilibrium and dynamic

  8. Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

    Science.gov (United States)

    Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

    2002-01-01

    Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

  9. Conducting Polymer 3D Microelectrodes

    Directory of Open Access Journals (Sweden)

    Jenny Emnéus

    2010-12-01

    Full Text Available Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements.

  10. Synthesis and Crosslinking of Polyether-Based Main Chain Benzoxazine Polymers and Their Gas Separation Performance

    Directory of Open Access Journals (Sweden)

    Muntazim Munir Khan

    2018-02-01

    Full Text Available The poly(ethylene glycol-based benzoxazine polymers were synthesized via a polycondensation reaction between Bisphenol-A, paraformaldehyde, and poly(ether diamine/(Jeffamine®. The structures of the polymers were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR, indicating the presence of a cyclic benzoxazine ring. The polymer solutions were casted on the glass plate and cross-linked via thermal treatment to produce tough and flexible films without using any external additives. Thermal properties and the crosslinking behaviour of these polymers were studied by thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. Single gas (H2, O2, N2, CO2, and CH4 transport properties of the crosslinked polymeric membranes were measured by the time-lag method. The crosslinked PEG-based polybenzoxazine membranes show improved selectivities for CO2/N2 and CO2/CH4 gas pairs. The good separation selectivities of these PEG-based polybenzoxazine materials suggest their utility as efficient thin film composite membranes for gas and liquid membrane separation technology.

  11. Thin films of metal-organic compounds and metal nanoparticle

    Indian Academy of Sciences (India)

    Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

  12. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  13. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  14. Single-Point Incremental Forming of Two Biocompatible Polymers: An Insight into Their Thermal and Structural Properties

    Directory of Open Access Journals (Sweden)

    Luis Marcelo Lozano-Sánchez

    2018-04-01

    Full Text Available Sheets of polycaprolactone (PCL and ultra-high molecular weight polyethylene (UHMWPE were fabricated and shaped by the Single-Point Incremental Forming process (SPIF. The performance of these biocompatible polymers in SPIF was assessed through the variation of four main parameters: the diameter of the forming tool, the spindle speed, the feed rate, and the step size based on a Box–Behnken design of experiments of four variables and three levels. The design of experiments allowed us to identify the parameters that most affect the forming of PCL and UHMWPE. The study was completed by means of a deep characterization of the thermal and structural properties of both polymers. These properties were correlated to the performance of the polymers observed in SPIF, and it was found that the polymer chains are oriented as a consequence of the SPIF processing. Moreover, by X-ray diffraction it was proved that polymer chains behave differently on each surface of the fabricated parts, since the chains on the surface in contact with the forming tool are oriented horizontally, while on the opposite surface they are oriented in the vertical direction. The unit cell of UHMWPE is distorted, passing from an orthorhombic cell to a monoclinic due to the slippage between crystallites. This slippage between crystallites was observed in both PCL and UHMWPE, and was identified as an alpha star thermal transition located in the rubbery region between the glass transition and the melting point of each polymer.

  15. Equivalence of chain conformations in the surface region of a polymer melt and a single Gaussian chain under critical conditions.

    Science.gov (United States)

    Skvortsov, A M; Leermakers, F A M; Fleer, G J

    2013-08-07

    In the melt polymer conformations are nearly ideal according to Flory's ideality hypothesis. Silberberg generalized this statement for chains in the interfacial region. We check the Silberberg argument by analyzing the conformations of a probe chain end-grafted at a solid surface in a sea of floating free chains of concentration φ by the self-consistent field (SCF) method. Apart from the grafting, probe chain and floating chains are identical. Most of the results were obtained for a standard SCF model with freely jointed chains on a six-choice lattice, where immediate step reversals are allowed. A few data were generated for a five-choice lattice, where such step reversals are forbidden. These coarse-grained models describe the equilibrium properties of flexible atactic polymer chains at the scale of the segment length. The concentration was varied over the whole range from φ = 0 (single grafted chain) to φ = 1 (probe chain in the melt). The number of contacts with the surface, average height of the free end and its dispersion, average loop and train length, tail size distribution, end-point and overall segment distributions were calculated for a grafted probe chain as a function of φ, for several chain lengths and substrate∕polymer interactions, which were varied from strong repulsion to strong adsorption. The computations show that the conformations of the probe chain in the melt do not depend on substrate∕polymer interactions and are very similar to the conformations of a single end-grafted chain under critical conditions, and can thus be described analytically. When the substrate∕polymer interaction is fixed at the value corresponding to critical conditions, all equilibrium properties of a probe chain are independent of φ, over the whole range from a dilute solution to the melt. We believe that the conformations of all flexible chains in the surface region of the melt are close to those of an appropriate single chain in critical conditions, provided

  16. Influence of Thin-Film Adhesives in Pullout Tests Between Nickel-Titanium Shape Memory Alloy and Carbon Fiber-Reinforced Polymer Matrix Composites

    Science.gov (United States)

    Quade, Derek J.; Jana, Sadhan; McCorkle, Linda S.

    2018-01-01

    Strips of nickel-titanium (NiTi) shape memory alloy (SMA) and carbon fiber-reinforced polymer matrix composite (PMC) were bonded together using multiple thin film adhesives and their mechanical strengths were evaluated under pullout test configuration. Tensile and lap shear tests were conducted to confirm the deformation of SMAs at room temperature and to evaluate the adhesive strength between the NiTi strips and the PMC. Optical and scanning electron microscopy techniques were used to examine the interfacial bonding after failure. Simple equations on composite tensile elongation were used to fit the experimental data on tensile properties. ABAQUS models were generated to show the effects of enhanced bond strength and the distribution of stress in SMA and PMC. The results revealed that the addition of thin film adhesives increased the average adhesive strength between SMA and PMC while halting the room temperature shape memory effect within the pullout specimen.

  17. Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound.

    Science.gov (United States)

    Tohmyoh, Hironori; Sakamoto, Yuhei

    2015-11-01

    This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

  18. Low-temperature oxidizing plasma surface modification and composite polymer thin-film fabrication techniques for tailoring the composition and behavior of polymer surfaces

    Science.gov (United States)

    Tompkins, Brendan D.

    This dissertation examines methods for modifying the composition and behavior of polymer material surfaces. This is accomplished using (1) low-temperature low-density oxidizing plasmas to etch and implant new functionality on polymers, and (2) plasma enhanced chemical vapor deposition (PECVD) techniques to fabricate composite polymer materials. Emphases are placed on the structure of modified polymer surfaces, the evolution of polymer surfaces after treatment, and the species responsible for modifying polymers during plasma processing. H2O vapor plasma modification of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), and 75A polyurethane (PU) was examined to further our understanding of polymer surface reorganization leading to hydrophobic recovery. Water contact angles (wCA) measurements showed that PP and PS were the most susceptible to hydrophobic recovery, while PC and HDPE were the most stable. X-ray photoelectron spectroscopy (XPS) revealed a significant quantity of polar functional groups on the surface of all treated polymer samples. Shifts in the C1s binding energies (BE) with sample age were measured on PP and PS, revealing that surface reorganization was responsible for hydrophobic recovery on these materials. Differential scanning calorimetry (DSC) was used to rule out the intrinsic thermal properties as the cause of reorganization and hydrophobic recovery on HDPE, LDPE, and PP. The different contributions that polymer cross-linking and chain scission mechanisms make to polymer aging effects are considered. The H2O plasma treatment technique was extended to the modification of 0.2 microm and 3.0 microm track-etched polycarbonate (PC-TE) and track-etched polyethylene terephthalate (PET-TE) membranes with the goal of permanently increasing the hydrophilicity of the membrane surfaces. Contact angle measurements on freshly treated and aged samples confirmed the wettability of the

  19. Optical sensor array platform based on polymer electronic devices

    Science.gov (United States)

    Koetse, Marc M.; Rensing, Peter A.; Sharpe, Ruben B. A.; van Heck, Gert T.; Allard, Bart A. M.; Meulendijks, Nicole N. M. M.; Kruijt, Peter G. M.; Tijdink, Marcel W. W. J.; De Zwart, René M.; Houben, René J.; Enting, Erik; van Veen, Sjaak J. J. F.; Schoo, Herman F. M.

    2007-10-01

    Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

  20. Structure and transport properties of polymer grafted nanoparticles

    KAUST Repository

    Goyal, Sushmit; Escobedo, Fernando A.

    2011-01-01

    We perform molecular dynamics simulations on a bead-spring model of pure polymer grafted nanoparticles (PGNs) and of a blend of PGNs with a polymer melt to investigate the correlation between PGN design parameters (such as particle core concentration, polymer grafting density, and polymer length) and properties, such as microstructure, particle mobility, and viscous response. Constant strain-rate simulations were carried out to calculate viscosities and a constant-stress ensemble was used to calculate yield stresses. The PGN systems are found to have less structural order, lower viscosity, and faster diffusivity with increasing length of the grafted chains for a given core concentration or grafting density. Decreasing grafting density causes depletion effects associated with the chains leading to close contacts between some particle cores. All systems were found to shear thin, with the pure PGN systems shear thinning more than the blend; also, the pure systems exhibited a clear yielding behavior that was absent in the blend. Regarding the mechanism of shear thinning at the high shear rates examined, it was found that the shear-induced decrease of Brownian stresses and increase in chain alignment, both correlate with the reduction of viscosity in the system with the latter being more dominant. A coupling between Brownian stresses and chain alignment was also observed wherein the non-equilibrium particle distribution itself promotes chain alignment in the direction of shear. © 2011 American Institute of Physics.

  1. Mechanism of Crystallization and Implications for Charge Transport in Poly(3-ethylhexylthiophene) Thin Films

    KAUST Repository

    Duong, Duc T.

    2014-04-09

    In this work, crystallization kinetics and aggregate growth of poly(3-ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X-ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time-dependent, field-effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2-3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter-aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics. Recrystallization kinetics and its relationship to charge transport in poly(3-ethylhexylthiophene) (P3EHT) thin films are investigated using a combination of grazing incidence X-ray diffraction, optical absorption, and field-effect transistor measurements. These results show that thin film crystallization kinetics is limited by polymer chain reorganization and that charge percolation depends strongly on the edge-to-edge distance between aggregates. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Towards single photon generation using NV centers in diamond coupled to thin layer optical waveguides

    International Nuclear Information System (INIS)

    Toshiyuki Tashima

    2014-01-01

    Single photon emitters like the nitrogen-vacancy (NV) center in diamond are important for quantum communication such as quantum cryptography and quantum metrology. In this context, e.g. tapered optical nano-fibers are a promising approach as they allow efficient coupling of single photons into a single spatial mode. Yet, integration of such fibers in a compact integrated quantum circuit is demanding. Here we propose a NV defect center in diamond as a single photon emitter coupled to a thin layer photonic waveguide. The benefit is to allow smaller size devices while having a similar strong evanescent field like tapered nano-optical fibers. We present numerical simulations and fabrication steps of such structures. (author)

  3. Applications of thin-film sandwich crystallization platforms

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

    2016-03-24

    Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  4. Integrated Instrumentation for Light-Emitting Polymers Development

    National Research Council Canada - National Science Library

    Jen, Alex

    2000-01-01

    The major objective of this project is to develop an integrated instrumentation that combines the capability of performing spin coating of uniform polymer thin films under an oxygen and moisture free...

  5. Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

    Science.gov (United States)

    Takemoto, Ichiki; Ando, Nobuo; Edamatsu, Kunishige; Fuji, Yusuke; Kuwana, Koji; Hashimoto, Kazuhiko; Funase, Junji; Yokoyama, Hiroyuki

    2007-03-01

    Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.

  6. Lithium ion intercalation in thin crystals of hexagonal TaSe2 gated by a polymer electrolyte

    Science.gov (United States)

    Wu, Yueshen; Lian, Hailong; He, Jiaming; Liu, Jinyu; Wang, Shun; Xing, Hui; Mao, Zhiqiang; Liu, Ying

    2018-01-01

    Ionic liquid gating has been used to modify the properties of layered transition metal dichalcogenides (TMDCs), including two-dimensional (2D) crystals of TMDCs used extensively recently in the device work, which has led to observations of properties not seen in the bulk. The main effect comes from the electrostatic gating due to the strong electric field at the interface. In addition, ionic liquid gating also leads to ion intercalation when the ion size of the gate electrolyte is small compared to the interlayer spacing of TMDCs. However, the microscopic processes of ion intercalation have rarely been explored in layered TMDCs. Here, we employed a technique combining photolithography device fabrication and electrical transport measurements on the thin crystals of hexagonal TaSe2 using multiple channel devices gated by a polymer electrolyte LiClO4/Polyethylene oxide (PEO). The gate voltage and time dependent source-drain resistances of these thin crystals were used to obtain information on the intercalation process, the effect of ion intercalation, and the correlation between the ion occupation of allowed interstitial sites and the device characteristics. We found a gate voltage controlled modulation of the charge density waves and a scattering rate of charge carriers. Our work suggests that ion intercalation can be a useful tool for layered materials engineering and 2D crystal device design.

  7. Thermoluminescence and photoluminescence analyses of MEH-PPV, MDMO-PPV and RU(bpy)3 gamma-irradiated polymer thin films

    International Nuclear Information System (INIS)

    Ortiz-Morales, A.; Ortiz-Lopez, J.; Cruz-Zaragoza, E.; Gómez-Aguilar, R.

    2015-01-01

    Effects of irradiation with 60 Co gamma photons on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3′,7′ dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Ru(bpy) 3 ) thin films were analyzed regarding their thermoluminescence (TL) and photoluminescence (PL) properties. A linear TL dose response was obtained from the MEH-PPV and MDMO-PPV polymer films in dose ranges of approximately 0.170–4.08 kGy and 0.170–0.850 kGy, respectively, followed by a supralinear behavior. A dependence on the conjugation length of the polymer chains which was favored by heating of the film, was observed, and irradiation generated a blue-shift in MEH-PPV and Ru(bpy) 3 . Furthermore, the PL structure was not modified. The most likely effect involved in the TL emission was trapping. The high activation energy values of the traps in the TL may be attributed in part to the binding energy of the exciton. A deconvolution process was carried out to obtain the kinetic parameters from the TL glow curves and PL spectra. - Highlights: • Irradiation effects on MEH-PPV, MDMO-PPV and Ru(bpy) 3 were analyzed by TL and PL. • The dose response of PPV derivatives was linear at higher doses (0.170–4.08 kGy). • Activation energy, was larger than 2 eV, suggest a possible good stability of traps. • PL spectra for non-irradiated and gamma irradiated polymer are almost identical

  8. Thermal characterization of semiconducting polymer bulk heterojunctions

    Science.gov (United States)

    Remy, Roddel A.

    Polymer semiconductors are intriguing due to their potential use in flexible electronics. Poly (3-hexylthiophene) (P3HT)--a very common polymer in this field--is semicrystalline and it is known that crystalline P3HT has a higher hole mobility than amorphous P3HT. Quantifying each fraction in the bulk and thin film states is therefore crucial to understanding its performance in transistor and other applications. In polymer solar cells, it acts as an electron donor and is typically mixed with the nanoparticle-like molecule, phenyl-C61-butyric acid methyl ester (PCBM)--an electron acceptor--in a thin film morphology termed a bulk heterojunction (BHJ). The structural hierarchy within the bulk heterojunction is complicated and its characterization, with a focus on P3HT morphology, is the topic of this dissertation. Calorimetry can play an important role in the elucidation of P3HT morphology with quantitative analysis of the crystalline and amorphous fractions present in the material. This was demonstrated by employing differential scanning calorimetry (DSC) to obtain the enthalpy of fusion of 100% crystalline P3HT (42.9 J/g) using oligomeric P3HT measurements. The more sensitive temperature modulated DSC (TMDSC) was then used to examine the glass transition of P3HT and the crystalline, mobile amorphous and rigid amorphous phases were quantified. The presence of these phases can play a large role in understanding the charge transfer process in polymer semiconductors. BHJ thin films of 50 wt.% PCBM were then analyzed and a polymer crystallinity of 30% was found after thermal annealing from initially non-crystalline polymer material. With assistance from previously acquired small angle neutron scattering data, a thorough analysis of the entire BHJ morphology was accomplished. A surprisingly large rigid amorphous polymer phase is present in the BHJ which could be located at the P3HT/PCBM interface, affecting charge transfer. Finally, interlayer diffusion of PCBM was

  9. New Solid Polymer Electrolytes for Improved Lithium Batteries

    Science.gov (United States)

    Hehemann, David G.

    2002-01-01

    The objective of this work was to identify, synthesize and incorporate into a working prototype, next-generation solid polymer electrolytes, that allow our pre-existing solid-state lithium battery to function better under extreme conditions. We have synthesized polymer electrolytes in which emphasis was placed on the temperature-dependent performance of these candidate electrolytes. This project was designed to produce and integrate novel polymer electrolytes into a lightweight thin-film battery that could easily be scaled up for mass production and adapted to different applications.

  10. The Role of Nanofillers in Polymer Nanocomposites

    Science.gov (United States)

    Xu, Di

    spherical fillers. Nanofillers have been widely used in polymer blends to improve the interfacial compatibility of otherwise immiscible polymers. In the second system, we investigated the interfacial behavior of binary polymer blends with different types of fillers. The interfacial tension and shear resistance were studied as a function of filler-polymer interaction, filler concentration and species of fillers. We found filler-polymer interaction is the key factor to improve the interfacial compatibility. The results show that nanofillers reduce both interfacial tension and interfacial slip at strong filler-polymer interaction. The effects of nanofillers however differ significantly from each other by their shapes. We analyzed the structure of nanofillers at the interface and their effects on the interfacial behaviors. The self-assembly of polymers into a columnar structure, while subject to a thin film environment, provides an economic route to fabricate polymer solar cell (PSC) with high conversion efficiency. In our work, we showed that two immiscible polymer segregates into to a percolating columnar structure when confined to a thin film. By adding nanofillers, with specific functionality, we can template the segregation of nanofillers to the polymer-polymer interface. We prove this process is surface tension driven and is a result that is particular for thin film geometries, where the thickness is under critical value. The results provide a theoretical basis for the column structure forming in a self-assembled PSC system, and can help to select polymer candidates that optimize PSC efficiency. These studies serve as theoretical guideline for engineering novel nanocomposites, and could lead to the design of materials with new and improved properties.

  11. Polymer Masks for nanostructuring of graphene

    DEFF Research Database (Denmark)

    Shvets, Violetta

    This PhD project is a part of Center for Nanostructured Graphene (CNG) activities. The aim of the project is to develop a new lithography method for creation of highly ordered nanostructures with as small as possible feature and period sizes. The method should be applicable for graphene nanostruc...... demonstrated the opening of what could be interpreted as a band gap....... polymer masks is developed. Mask fabrication is realized by microtoming of 30-60 nm thin sections from pre-aligned polymer monoliths with different morphologies. The resulting polymer masks are then transferred to both silicon and graphene substrates. Hexagonally packed hole patterns with 10 nm hole...

  12. Effects of polymer-nanoparticle interactions on the viscosity of unentangled polymers under extreme nanoconfinement during capillary rise infiltration.

    Science.gov (United States)

    Hor, Jyo Lyn; Wang, Haonan; Fakhraai, Zahra; Lee, Daeyeon

    2018-03-28

    We explore the effect of confinement and polymer-nanoparticle interactions on the viscosity of unentangled polymers undergoing capillary rise infiltration (CaRI) in dense packings of nanoparticles. In CaRI, a polymer is thermally induced to wick into the dense packings of nanoparticles, leading to the formation of polymer-infiltrated nanoparticle films, a new class of thin film nanocomposites with extremely high concentrations of nanoparticles. To understand the effect of this extreme nanoconfinement, as well as polymer-nanoparticle interactions on the polymer viscosity in CaRI films, we use two polymers that are known to have very different interactions with SiO2 nanoparticles. Using in situ spectroscopic ellipsometry, we monitor the polymer infiltration process, from which we infer the polymer viscosity based on the Lucas-Washburn model. Our results suggest that physical confinement increases the viscosity by approximately two orders of magnitude. Furthermore, confinement also increases the glass transition temperature of both polymers. Thus, under extreme nanoconfinement, the physical confinement has a more significant impact than the polymer-nanoparticle interactions on the viscosity of unentangled polymers, measured through infiltration dynamics, as well as the glass transition temperature. These findings will provide fundamental frameworks for designing processes to enable the fabrication of CaRI nanocomposite films with a wide range of nanoparticles and polymers.

  13. Carbon nanotube network thin-film transistors on flexible/stretchable substrates

    Science.gov (United States)

    Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

    2016-03-29

    This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

  14. Distortion of chain conformation and reduced entanglement in polymer-graphene oxide nanocomposites

    Science.gov (United States)

    Weir, Michael; Boothroyd, Stephen; Johnson, David; Thompson, Richard; Coleman, Karl; Clarke, Nigel

    Graphene and related two-dimensional materials are excellent candidates as filler materials in polymer nanocomposites due to their extraordinary physical properties and high aspect ratio. To explore the mechanism by which the filler affects the bulk properties of these unique systems, and to build understanding from the macromolecular level upwards, we use a combination of small-angle neutron scattering (SANS) and oscillatory rheology. Where a good dispersion is achieved in poly(methyl methacrylate)-graphene oxide (PMMA-GO) nanocomposites, we observe a reduction in the polymer radius of gyration with increasing GO concentration that is consistent with the predicted behavior of polymer melt chains at a solid interface. We use concepts from thin-film polymer physics to formulate a scaling relation for the reduction in entanglements caused by the GO interfaces. Using these scaling arguments, we utilize SANS results to directly estimate the changes to the elastic plateau modulus of the network of entangled polymer chains, and find a correlation with the measured bulk rheology. We present a direct link between interfacial confinement effects and the bulk polymer nanocomposite properties, whilst demonstrating a model system for measuring thin film polymer physics in the bulk.

  15. Direct covalent coupling of proteins to nanostructured plasma polymers: a route to tunable cell adhesion

    International Nuclear Information System (INIS)

    Melnichuk, Iurii; Choukourov, Andrei; Bilek, Marcela; Weiss, Anthony; Vandrovcová, Marta; Bačáková, Lucie; Hanuš, Jan; Kousal, Jaroslav; Shelemin, Artem; Solař, Pavel

    2015-01-01

    Highlights: • Flat and nanostructured interfaces were overcoated by hydrocarbon plasma polymer. • Linker-free covalent attachment of proteins to resultant surfaces was validated. • Ultra-thin hydrocarbon overcoat (<2 nm) secured prolonged effective binding. • Pre-adsorbed tropoelastin promoted proliferation of osteoblast-like MG-63 cells. • Nanostructured films were multi-affine and impeded cell adhesion. - Abstract: Flat and nanostructured thin films were fabricated by deposition of ultra-thin (<2 nm) layer of hydrocarbon plasma polymer over polished silicon and over a pattern of 8 nm-thick poly(ethylene) islands on silicon. Linker-free radical-based covalent binding of bovine serum albumin and tropoelastin was confirmed for both types of films. The binding capability of albumin was found to be stable over many days of ambient air storage time. Tropoelastin-mediated flat plasma polymers favored adhesion and proliferation of osteoblast-like MG-63 cells. Nanostructured plasma polymers were multi-affine and their hierarchical surface represented an additional barrier for cell attachment

  16. Polymer optical fiber Bragg grating inscription with a single UV laser pulse

    DEFF Research Database (Denmark)

    Pospori, Andreas; Marques, A.T.; Bang, Ole

    2017-01-01

    We experimentally demonstrate the first polymer optical fiber Bragg grating inscribed with only one krypton fluoride laser pulse. The device has been recorded in a single-mode poly(methyl methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One...... laser pulse with a duration of 15 ns, which provide energy density of 974 mJ/cm2, is adequate to introduce a refractive index change of 0.74×10-4 in the fiber core. After the exposure, the reflectivity of the grating increases for a few minutes following a second order exponential saturation...

  17. Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

    KAUST Repository

    Ayzner, Alexander L.; Mei, Jianguo; Appleton, Anthony; DeLongchamp, Dean; Nardes, Alexandre; Benight, Stephanie; Kopidakis, Nikos; Toney, Michael F.; Bao, Zhenan

    2015-01-01

    © 2015 American Chemical Society. Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

  18. Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

    KAUST Repository

    Ayzner, Alexander L.

    2015-12-30

    © 2015 American Chemical Society. Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

  19. Single-domain versus two-domain configuration in thin ferromagnetic prisms

    International Nuclear Information System (INIS)

    Pini, Maria Gloria; Politi, Paolo

    2007-01-01

    Thin ferromagnetic elements in the form of rectangular prisms are theoretically investigated in order to study the transition from single-domain to two-domain state, with changing the in-plane aspect ratio p. We address two main questions: first, how general is the transition; second, how the critical value p c depends on the physical parameters. We use two complementary methods: discrete-lattice calculations and a micromagnetic continuum approach. Ultrathin films do not appear to split in two domains. Instead, thicker films may undergo the above transition. We have used the continuum approach to analyze recent magnetic force microscopy observations in 30nm-thick patterned permalloy elements, finding a good agreement for p c

  20. Polymer poling characterization using second harmonic generation (SHG)

    Science.gov (United States)

    Tellier, Gildas; Averty, Dominique; Blart, Errol; Boisrobert, Christian; Gundel, Hartmut; Le Tacon, Sylvain; Monnereau, Cyrille; Odobel, Fabrice; Seveno, Raynald

    2006-04-01

    Several polymer molecules have structures which are suitable for the non-linear optic applications. We report on the design and fabrication of a high performance electro-optic modulator made of polymer thin films. The polymer we study contains a chromophore based on Disperse Red One covalently grafted to a host-matrix. The polymer materials are deposited in thin layers on a glass substrate by chemical solution deposition, either by spin-coating or by dip-coating. The thickness of the films is ranging from a hundred nanometers to several micrometers. Initially, the polymer molecules are randomly oriented and the films are isotropic, hence no electro-optic effect can be observed. In order to break the symmetry and align the chromophores, the films are submitted to the so-called corona poling process. As a result, their structure become non-centrosymmetric and the second-order susceptibility is no longer zero. The corona poling method consists of applying a high electric field to the polymer by means of a needle electrode, placed above the polymer film which is posed on a grounded sample support electrode. Thermal regulation of the support electrode allows to control the temperature during the poling of the films. Once the poling process has been established, a chemical cross-linking function is thermally activated in order to fix the orientation of the chromophores in the polymer matrix. The orientation and its stability in time is evaluated with a Second Harmonic Generation measurement set-up using the Makers Fringes configuration. We studied the influence of the poling temperature, the distance between the corona needle electrode and the sample, the high voltage applied, and the duration of the poling process on the efficiency of chromophore orientation in order to optimize the poling procedure. Finally, aging of poled polymer samples has been investigated at elevated temperatures, confirming the stability of the cross-linking process.

  1. HWCVD of polymers: Commercialization and scale-up

    International Nuclear Information System (INIS)

    Pryce Lewis, Hilton G.; Bansal, Neeta P.; White, Aleksandr J.; Handy, Erik S.

    2009-01-01

    GVD Corporation specializes in process development and equipment design for the production of ultra-thin polymer coatings using hot wire chemical vapor deposition (HWCVD, also known as initiated chemical vapor deposition, iCVD). HWCVD allows many coating compositions to be produced, including fluorocarbon and silicone polymers, copolymers, and vinyl hydrocarbon polymers. It is especially valuable for creating ultra-thin layers of insoluble, infusible polymers which are hard to process by conventional means, such as polytetrafluoroethylene (PTFE, Teflon. HWCVD PTFE coatings are chemically robust, comprised of essentially 100% CF 2 , resistant to solvents, conformal to complex surface geometry, and have excellent adhesion to a wide range of substrates. Since the part to be coated remains at room temperature, fragile materials like plastics and fabrics can be coated with ease. GVD has focused on scale-up of the process equipment and has developed several standard coating systems, which will be discussed in this paper. These include laboratory-scale batch coating systems, a medium sized production batch coating system, a large scale custom batch coater, and a pilot scale roll-to-roll web coater. All of GVD's systems are complete with fully automated, computer based control systems and include options for effluent monitors and an exhaust scrubber.

  2. Capillary levelling as a probe of rheology in polymer thin films

    Science.gov (United States)

    McGraw, Joshua D.; Jago, Nick M.; Dalnoki-Veress, Kari

    2011-03-01

    While measuring the rheology of bulk polymer systems is routine, when the size of a system becomes comparable to the molecular size, flow properties are poorly understood and hard to measure. Here, we present the results of experiments that are easily performed and can probe the rheological properties of polymer films that are mere tens of nanometres in thickness. We prepare glassy bilayer polymer films with height profiles well approximated by a step function. Upon annealing above the glass transition, broadening of the height profiles due to gradients in the Laplace pressure is observed. By validating the technique as a probe of the rheology with a range of molecular weights, we will show that this robust technique can be used to investigate the effects of confinement and interfaces on the rheology of ultrathin polymer films. Financial support from NSERC of Canada is gratefully acknowledged.

  3. Conducting polymer based biomolecular electronic devices

    Indian Academy of Sciences (India)

    Characterization of conducting polymers has been considered to be very .... and CH4) on surface plasmon resonance of Langmuir–Blodgett films of ..... [37] D G Zhu, M C Petty, H Ancelin and J Yarwood, Thin Solid Films 176, 151 (1989).

  4. Thin Films Formed from Conjugated Polymers with Ionic, Water-Soluble Backbones

    NARCIS (Netherlands)

    Voortman, Thomas P; Chiechi, Ryan C

    2015-01-01

    This paper compares the morphologies of films of conjugated polymers in which the backbone (main chain) and pendant groups are varied between ionic/hydrophilic and aliphatic/hydrophobic. We observe that conjugated polymers in which the pendant groups and backbone are matched, either ionic-ionic or

  5. Smart Surface Chemistries of Conducting Polymers

    DEFF Research Database (Denmark)

    Lind, Johan Ulrik

    In this thesis we investigate post-polymerization covalent modifications of poly(3,4-dioxythiophene (PEDOT)-type conducting polymers. The aim of the modifications is to gain specific control of the interaction between the material and living mammalian cells. The use of “click-chemistry” to modify...... a straightforward and in-expensive method for patterning conducting polymer thin films into microelectrodes, without losing control of the surface chemistry of the samples. On the contrary, the method provides direct control of the surface chemistry of both the fabricated micro-electrodes and the gaps between them....... The method is based on locally removing PEDOTtype polymers to expose underlying non-conducting functional polymer substrates. Thereby, multifunctional substrates are obtained. By applying this method, we are able to fabricate allpolymer micro-systems with multiple types of localized functional (bio...

  6. Velocity dependence of friction of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.

    2009-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate, and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional...... shear stress for both cases. In our simulations, the polymer films are very thin (approx. 3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  7. Thin metal bilayer for surface plasmon resonance sensors in a multimode plastic optical fiber: the case of palladium and gold metal films

    Science.gov (United States)

    Cennamo, Nunzio; Zuppella, Paola; Bacco, Davide; Corso, Alain J.; Pelizzo, Maria G.; Pesavento, Maria; Zeni, Luigi

    2016-05-01

    A novel sensing platform based on thin metal bilayer for surface plasmon resonance (SPR) in a D-shaped plastic optical fiber (POF) has been designed, implemented and tested. The experimental results are congruent with the numerical studies. This platform has been properly optimized to work in the 1.38 -1.42 refractive index range and it exhibits excellent sensitivity. This refractive index range is very interesting for bio-chemical applications, where the polymer layer are used as receptors (e.g. molecularly imprinted polymer) or to immobilize the bio-receptor on the metal surface. The proposed metallic bilayer is based on palladium and gold films and replaces the traditional gold by exhibiting higher performances. Furthermore, the deposition of the thin bilayer is a single process and no further manufacturing step is required. In fact, in this case the photoresist buffer layer between the POF core and the metal layer, usually required to increase the refractive index range, is no longer necessary.

  8. Relaxation induced optical anisotropy during dynamic overshoot swelling of zwitterionic polymer films

    NARCIS (Netherlands)

    Ogieglo, Wojciech; de Grooth, Joris; Wormeester, Herbert; Wessling, Matthias; Nijmeijer, Dorothea C.; Benes, Nieck Edwin

    2013-01-01

    In-situ spectroscopic ellipsometry was used to investigate the swelling behavior of thin supported zwitterionic polymers based on sulfobetaine methacrylate and n-butylacrylate. This material represents an interesting class of zwitterionic polymers, with large potential in reduction of biofouling of

  9. Strain-dependent characterization of electrode and polymer network of electrically activated polymer actuators

    Science.gov (United States)

    Töpper, Tino; Osmani, Bekim; Weiss, Florian M.; Winterhalter, Carla; Wohlfender, Fabian; Leung, Vanessa; Müller, Bert

    2015-04-01

    Fecal incontinence describes the involuntary loss of bowel content and affects about 45 % of retirement home residents and overall more than 12 % of the adult population. Artificial sphincter implants for treating incontinence are currently based on mechanical systems with failure rates resulting in revision after three to five years. To overcome this drawback, artificial muscle sphincters based on bio-mimetic electro-active polymer (EAP) actuators are under development. Such implants require polymer films that are nanometer-thin, allowing actuation below 24 V, and electrodes that are stretchable, remaining conductive at strains of about 10 %. Strain-dependent resistivity measurements reveal an enhanced conductivity of 10 nm compared to 30 nm sputtered Au on silicone for strains higher than 5 %. Thus, strain-dependent morphology characterization with optical microscopy and atomic force microscopy could demonstrate these phenomena. Cantilever bending measurements are utilized to determine elastic/viscoelastic properties of the EAP films as well as their long-term actuation behavior. Controlling these properties enables the adjustment of growth parameters of nanometer-thin EAP actuators.

  10. Effects of Sb-doping on the grain growth of Cu(In, Ga)Se2 thin films fabricated by means of single-target sputtering

    International Nuclear Information System (INIS)

    Zhang, Shu; Wu, Lu; Yue, Ruoyu; Yan, Zongkai; Zhan, Haoran; Xiang, Yong

    2013-01-01

    To investigate the effects of Sb doping on the kinetics of grain growth in Cu(In,Ga)Se 2 (CIGS) thin films during annealing, CIGS thin films were sputtered onto Mo coated substrates from a single CIGS alloy target, followed by chemical bath deposition of Sb 2 S 3 thin layers on top of CIGS layers and subsequent annealing at different temperatures for 30 min in Se vapors. X-ray diffraction results showed that CIGS thin films were obtained directly using the single-target sputtering method. After annealing, the In/Ga ratio in Sb-doped CIGS thin films remained stable compared to undoped film, possibly because Sb can promote the incorporation of Ga into CIGS. The grain growth in CIGS thin films was enhanced after Sb doping, exhibiting significantly larger grains after annealing at 400 °C or 450 °C compared to films without Sb. In particular, the effect was strikingly significant in grain growth across the film thickness, resulting in columnar grain structure in Sb-doped films. This grain growth improvement may be led by the diffusion of Sb from the front surface to the CIGS-Mo back interface, which promoted the mass transport process in CIGS thin films. - Highlights: ► Cu(In,Ga)Se 2 (CIGS) thin films made by sputtering from a single CIGS target. ► Chemical bath deposition used to introduce antimony into CIGS absorber layers. ► In/Ga ratio decreases in Sb-doped annealed films, comparatively to undoped films. ► Sb-doped CIGS films are superior to undoped films in terms of grain-growth kinetics

  11. 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)

    Shang, Ke; Geng, Yuanyuan; Xu, Xingtao; Wang, Changwei; Lee, Yong-Ill; Hao, Jingcheng; Liu, Hong-Guo

    2014-01-01

    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 HAuCl 4 . 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 AuCl 4 − 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 KBH 4 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 KBH 4 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

  12. Unique self-assembly behavior of a triblock copolymer and fabrication of catalytically active gold nanoparticle/polymer thin films at the liquid/liquid interface

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Ke; Geng, Yuanyuan; Xu, Xingtao [Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100 (China); Wang, Changwei [Environmental Monitoring Center of Shandong Province, Jinan 250013 (China); Lee, Yong-Ill [Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Hao, Jingcheng [Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100 (China); Liu, Hong-Guo, E-mail: hgliu@sdu.edu.cn [Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100 (China)

    2014-07-01

    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 HAuCl{sub 4}. 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 AuCl{sub 4}{sup −} 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 KBH{sub 4} 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 KBH{sub 4} 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

  13. Characterization of plasticized PMMA–LiBF4 based solid polymer ...

    Indian Academy of Sciences (India)

    Unknown

    Polymer electrolyte films prepared from poly(methyl methacrylate) and LiBF4 with different con- centrations of ... 1. Introduction. Many types of ionically conducting polymers, generally ... 2. Experimental. Thin films of PMMA–LiBF4–DBP in different mole ratios ... remains very close to that of a liquid electrolyte. It is con-.

  14. 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.

  15. Adsorption and flocculation by polymers and polymer mixtures.

    Science.gov (United States)

    Gregory, John; Barany, Sandor

    2011-11-14

    Polymers of various types are in widespread use as flocculants in several industries. In most cases, polymer adsorption is an essential prerequisite for flocculation and kinetic aspects are very important. The rates of polymer adsorption and of re-conformation (relaxation) of adsorbed chains are key factors that influence the performance of flocculants and their mode of action. Polyelectrolytes often tend to adopt a rather flat adsorbed configuration and in this state their action is mainly through charge effects, including 'electrostatic patch' attraction. When the relaxation rate is quite low, particle collisions may occur while the adsorbed chains are still in an extended state and flocculation by polymer bridging may occur. These effects are now well understood and supported by much experimental evidence. In recent years there has been considerable interest in the use of multi-component flocculants, especially dual-polymer systems. In the latter case, there can be significant advantages over the use of single polymers. Despite some complications, there is a broad understanding of the action of dual polymer systems. In many cases the sequence of addition of the polymers is important and the pre-adsorbed polymer can have two important effects: providing adsorption sites for the second polymer or causing a more extended adsorbed conformation as a result of 'site blocking'. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Investigation of the flow structure in thin polymer films using 3D µPTV enhanced by GPU

    Science.gov (United States)

    Cavadini, Philipp; Weinhold, Hannes; Tönsmann, Max; Chilingaryan, Suren; Kopmann, Andreas; Lewkowicz, Alexander; Miao, Chuan; Scharfer, Philip; Schabel, Wilhelm

    2018-04-01

    To understand the effects of inhomogeneous drying on the quality of polymer coatings, an experimental setup to resolve the occurring flow field throughout the drying film has been developed. Deconvolution microscopy is used to analyze the flow field in 3D and time. Since the dimension of the spatial component in the direction of the line-of-sight is limited compared to the lateral components, a multi-focal approach is used. Here, the beam of light is equally distributed on up to five cameras using cubic beam splitters. Adding a meniscus lens between each pair of camera and beam splitter and setting different distances between each camera and its meniscus lens creates multi-focality and allows one to increase the depth of the observed volume. Resolving the spatial component in the line-of-sight direction is based on analyzing the point spread function. The analysis of the PSF is computational expensive and introduces a high complexity compared to traditional particle image velocimetry approaches. A new algorithm tailored to the parallel computing architecture of recent graphics processing units has been developed. The algorithm is able to process typical images in less than a second and has further potential to realize online analysis in the future. As a prove of principle, the flow fields occurring in thin polymer solutions drying at ambient conditions and at boundary conditions that force inhomogeneous drying are presented.

  17. Channel formation in single-monolayer pentacene thin film transistors

    International Nuclear Information System (INIS)

    Park, B-N; Seo, Soonjoo; Evans, Paul G

    2007-01-01

    The geometrical arrangement of single-molecule-high islands and the contact between them have large roles in determining the electrical properties of field effect transistors (FETs) based on monolayer-scale pentacene thin films. As the pentacene coverage increases through the submonolayer regime there is a percolation transition where islands come into contact and a simultaneous rapid onset of current. At coverages just above the percolation threshold, the electrical properties vary with geometrical changes in the contacts between the pentacene islands. At higher coverages, the FET mobility is much lower than the mobility measured by the van der Pauw method because of high contact resistances in monolayer-scale pentacene film devices. An increase in the van der Pauw mobility of holes as a function of pentacene coverage shows that second layer islands take part in charge transport

  18. Hydrophobicity studies of polymer thin films with varied CNT concentration

    Science.gov (United States)

    M. Rodzi, N. H.; M. Shahimin, M.; Poopalan, P.; Man, B.; M. Nor, M. N.

    2013-12-01

    Surface functionalization studies for re-creating a `Lotus Leaf' effect (superhydrophobic) have been carried out for the past decade; looking for the material which can provide high transparency, low energy surface and high surface roughness. Fabrication of polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNT) hybrid thin film variations on glass to produce near-superhydrophobic surfaces is presented in this paper. There are three important parameters studied in producing hydrophobic surfaces based on the hybrid thin films; concentration of PDMS, concentration of MWCNT and droplet sizes. The study is carried out by using PDMS of varied cross linker ratio (10:1, 30:1 and 50:1) with MWCNT concentration of 1mg, 10mg and 15mg for 0.5 μl, 2.0 μl, 5.0 μl and 10 μl droplet sizes. The resulting hybrid thin films show that hydrophobicity increased with increasing cross linker ratio and MWCNT percentage in the PDMS solution. A near superhydrophobic surface can be created when using 15 mg of MWCNT with 50:1 cross linker ratio PDMS thin films, measured on 10 μl droplet size. The hybrid thin films produced can be potentially tailored to the application of biosensors, MEMS and even commercial devices.

  19. Writing on ultra thin uniaxially oriented polymer films with an electron beam

    International Nuclear Information System (INIS)

    Petermann, J.; Wenderoth, K.

    1990-01-01

    Information storage polymers have been described and used for many years. When using an electron beam to store information, chemical changes in the macromolecules via local radiation damage is utilized to print the information into the polymer. This letter reports the writing of optically detectable information into birefringent polymer films. The method is based on the fact that preferred orientation of the macromolecules can be destroyed by electron radiation damage. The damage is produced by an electron beam in a transmission electron microscope. The resulting information is observed optically in a polarizing microscope. The polymer films used in the present study were polybutene 1 (PB 1), polyethylene (PE) and polyvinyl-idenfluoride (PVDF). (author)

  20. Weathering resistance of thin plasma polymer films on pre-coated steel =

    Science.gov (United States)

    Serra, Ricardo Gil Henriques

    O trabalho apresentado teve origem no projecto de investigacao “Tailored Thin Plasma Polymers Films for Surface Engineering of Coil Coated Steel”, financiado pelo Programa Europeu ECSC Steel Research. Sistemas de aco galvanizado pre-pintado em banda a base de poliester e poliuretano foram submetidos a um processo de polimerizacao por plasma onde um filme fino foi depositado de modo a modificar as propriedades de superficie. Foram usados reactores de catodo oco, microondas e radio frequencia para a deposicao do polimero fino. Os sistemas preparados foram analisados de modo a verificar a influencia do processo de polimerizacao por plasma na alteracao das propriedades barreira dos sistemas pre-pintados em banda. Foi estudado o efeito dos diferentes passos do processo de polimerizacao por plasma, bem como o efeito de diferentes variaveis operatorias. A mistura precursora foi variada de modo a modificar as propriedades da superficie de modo a poder vir a obter maior hidrofobicidade, maior resistencia a marcas digitais, bem como maior facilidade de limpeza. Os testes foram conduzidos em solucao de NaCl 0,5 M. Para o trabalho foram usadas tecnicas de analise da morfologia da superficie como Microscopia de Forca Atomica e Microscopia Electronica de Varrimento. As propriedades electroquimicas dos sistemas foram estudadas por Espectroscopia de Impedancia Electroquimica. A estrutura dos filmes gerados no processo de polimerizacao por plasma foi caracterizada por Microscopia de Transmissao Electronica. A modificacao das propriedades opticas devido ao processo de polimerizacao por plasma foi tambem obtida.

  1. The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

    Science.gov (United States)

    Tarigan, Johannes; Meka, Randi; Nursyamsi

    2018-03-01

    Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

  2. High performance inkjet-printed metal oxide thin film transistors via addition of insulating polymer with proper molecular weight

    Science.gov (United States)

    Sun, Dawei; Chen, Cihai; Zhang, Jun; Wu, Xiaomin; Chen, Huipeng; Guo, Tailiang

    2018-01-01

    Fabrication of metal oxide thin film transistor (MOTFT) arrays using the inkjet printing process has caused tremendous interest for low-cost and large-area flexible electronic devices. However, the inkjet-printed MOTFT arrays usually exhibited a non-uniform geometry due to the coffee ring effect, which restricted their commercial application. Therefore, in this work, a strategy is reported to control the geometry and enhance device performance of inkjet-printed MOTFT arrays by the addition of an insulating polymer to the precursor solution prior to film deposition. Moreover, the impact of the polymer molecular weight (MW) on the geometry, chemical constitution, crystallization, and MOTFT properties of inkjet-printed metal oxide depositions was investigated. The results demonstrated that with an increase of MW of polystyrene (PS) from 2000 to 200 000, the coffee ring was gradually faded and the coffee ring effect was completely eliminated when MW reached 200 000, which is associated with the enhanced viscosity with the insulating polymer, providing a high resistance to the outward capillary flow, which facilitated the depinning of the contact line, leading to the elimination of the coffee ring. More importantly, the carrier mobility increased significantly from 4.2 cm2 V-1 s-1 up to 13.7 cm2 V-1 s-1 as PS MW increased from 2000 to 200 000, which was about 3 times that of the pristine In2O3 TFTs. Grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy results indicated that PS doping of In2O3 films not only frustrated crystallization but also altered chemical constitution by enhancing the formation of the M-O structure, both of which facilitated the carrier transport. These results demonstrated that the simple polymer additive process provides a promising method that can efficiently control the geometry of MO arrays during inkjet printing and maximize the device performance of MOTFT arrays, which showed great potential for the application in next

  3. Bilaterally Microstructured Thin Polydimethylsiloxane Film Production

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Yu, Liyun; Hassouneh, Suzan Sager

    2015-01-01

    Thin PDMS films with complex microstructures are used in the manufacturing of dielectric electro active polymer (DEAP) actuators, sensors and generators, to protect the metal electrode from large strains and to assure controlled actuation. The current manufacturing process at Danfoss Polypower A/...

  4. Thin film complementary metal oxide semiconductor (CMOS) device using a single-step deposition of the channel layer

    KAUST Repository

    Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Wang, Zhenwei; Hedhili, Mohamed N.; Wang, Q. X.; Alshareef, Husam N.

    2014-01-01

    We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n-and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling

  5. Physical processes in azobenzene polymers on irradiation with polarized light

    DEFF Research Database (Denmark)

    Holme, N.C.R.; Nikolova, L.; Norris, T.B.

    1999-01-01

    Azobenzenes can serve as model compounds for the study of trans-cis isomerization in more complex molecules. We have performed time-resolved spectroscopy in solutions containing free azobenzene chromophores and diols with a view to obtaining the energy levels and lifetimes of the excited states....... A transition route based on experimental results for the theoretically calculated energy level scheme is proposed. Physical observations of surface relief in thin films of azobenzene polymers when irradiated with polarized light are reported. These include two beam polarization holographic observations...... and single beam transmission measurements through a mask, followed by atomic force microscope and profiler investigations. It is concluded that none of the prevalent theories can explain all the observed facts....

  6. Productivity and cost of marking activities for single-tree selection and thinning treatments in Arkansas

    Science.gov (United States)

    Tymur Sydor; Richard A. Kluender; Rodney L. Busby; Matthew Pelkki

    2004-01-01

    An activity algorithm was developed for standard marking methods for natural pine stands in Arkansas. For the two types of marking methods examined, thinning (selection from below) and single-tree selection (selection from above), cycle time and cost models were developed. Basal area (BA) removed was the major influencing factor in both models. Marking method was...

  7. Layer-by-layer assembly of thin film oxygen barrier

    International Nuclear Information System (INIS)

    Jang, Woo-Sik; Rawson, Ian; Grunlan, Jaime C.

    2008-01-01

    Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation ( 2 /day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging

  8. Formation of SmFe5(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    International Nuclear Information System (INIS)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-01-01

    SmFe 5 (0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe 5 structure forming an alloy compound of Sm(Fe,Cu) 5 . The Sm(Fe,Cu) 5 film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  9. Thin inclusion approach for modelling of heterogeneous conducting materials

    Science.gov (United States)

    Lavrov, Nikolay; Smirnova, Alevtina; Gorgun, Haluk; Sammes, Nigel

    Experimental data show that heterogeneous nanostructure of solid oxide and polymer electrolyte fuel cells could be approximated as an infinite set of fiber-like or penny-shaped inclusions in a continuous medium. Inclusions can be arranged in a cluster mode and regular or random order. In the newly proposed theoretical model of nanostructured material, the most attention is paid to the small aspect ratio of structural elements as well as to some model problems of electrostatics. The proposed integral equation for electric potential caused by the charge distributed over the single circular or elliptic cylindrical conductor of finite length, as a single unit of a nanostructured material, has been asymptotically simplified for the small aspect ratio and solved numerically. The result demonstrates that surface density changes slightly in the middle part of the thin domain and has boundary layers localized near the edges. It is anticipated, that contribution of boundary layer solution to the surface density is significant and cannot be governed by classic equation for smooth linear charge. The role of the cross-section shape is also investigated. Proposed approach is sufficiently simple, robust and allows extension to either regular or irregular system of various inclusions. This approach can be used for the development of the system of conducting inclusions, which are commonly present in nanostructured materials used for solid oxide and polymer electrolyte fuel cell (PEMFC) materials.

  10. Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

    Science.gov (United States)

    Challa, Ravi Kumar

    , fiber and minerals, simulated thin stillage was prepared with carbohydrate mixtures and tested for fouling rates. Induction period, maximum fouling resistance and mean fouling rates were determined. Two experiments were performed with two varieties of starch, waxy and high amylose and short chain carbohydrates, corn syrup solids and glucose. Interaction effects of glucose with starch varieties were studied. In the first experiment, short chain carbohydrates individual and interaction effects with starch were studied. For mixtures prepared from glucose and corn syrup solids, no fouling was observed. Mixtures prepared from starch, a long glucose polymer, showed marked fouling. Corn syrup solids and glucose addition to pure starch decreased the mean fouling rates and maximum fouling resistances. Between corn syrup solids and glucose, starch fouling rates were reduced with addition of glucose. Induction periods of pure mixtures of either glucose or corn syrup solids were longer than the test period (5 h). Pure starch mixture had no induction period. Maximum fouling resistance was higher for mixtures with higher concentration of longer polymers. Waxy starch had a longer induction period than high amylose starch. Maximum fouling resistance was higher for waxy than high amylose starch. Addition of glucose to waxy or high amylose starch increased induction period of mixtures longer than 5 h test period. It appears that the bulk fluid temperature plays an important role on carbohydrate mixture fouling rates. Higher bulk fluid temperatures increased the initial fouling rates of the carbohydrate mixtures. Carbohydrate type, depending on the polymer length, influenced the deposit formation. Longer chain carbohydrate, starch, had higher fouling rates compared to shorter carbohydrates such as glucose and corn syrup solids. For insoluble carbohydrate mixtures, fouling was severe. As carbohydrate solubility increased with bulk fluid temperature, surface reaction increased at probe

  11. High-density polymer microarrays: identifying synthetic polymers that control human embryonic stem cell growth.

    Science.gov (United States)

    Hansen, Anne; Mjoseng, Heidi K; Zhang, Rong; Kalloudis, Michail; Koutsos, Vasileios; de Sousa, Paul A; Bradley, Mark

    2014-06-01

    The fabrication of high-density polymer microarray is described, allowing the simultaneous and efficient evaluation of more than 7000 different polymers in a single-cellular-based screen. These high-density polymer arrays are applied in the search for synthetic substrates for hESCs culture. Up-scaling of the identified hit polymers enables long-term cellular cultivation and promoted successful stem-cell maintenance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals.

    Science.gov (United States)

    Kamlapure, Anand; Saraswat, Garima; Ganguli, Somesh Chandra; Bagwe, Vivas; Raychaudhuri, Pratap; Pai, Subash P

    2013-12-01

    We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350 mK and in magnetic fields up to 9 T, with thin film deposition and in situ single crystal cleaving capabilities. The main focus lies on the simple design of STM head and a sample holder design that allows us to get spectroscopic data on superconducting thin films grown in situ on insulating substrates. Other design details on sample transport, sample preparation chamber, and vibration isolation schemes are also described. We demonstrate the capability of our instrument through the atomic resolution imaging and spectroscopy on NbSe2 single crystal and spectroscopic maps obtained on homogeneously disordered NbN thin film.

  13. Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

    KAUST Repository

    Habuchi, Satoshi; Yamamoto, Takuya; Tezuka, Yasuyuki

    2016-01-01

    We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used

  14. Grid-connected polymer solar panels: initial considerations of cost, lifetime, and practicality.

    Science.gov (United States)

    Medford, Andrew J; Lilliedal, Mathilde R; Jørgensen, Mikkel; Aarø, Dennis; Pakalski, Heinz; Fyenbo, Jan; Krebs, Frederik C

    2010-09-13

    Large solar panels were constructed from polymer solar cell modules prepared using full roll-to-roll (R2R) manufacture based on the previously published ProcessOne. The individual flexible polymer solar modules comprising multiple serially connected single cell stripes were joined electrically and laminated between a 4 mm tempered glass window and black Tetlar foil using two sheets of 0.5 mm thick ethylene vinyl acetate (EVA). The panels produced up to 8 W with solar irradiance of ~960 Wm⁻², and had outer dimensions of 1 m x 1.7 m with active areas up to 9180 cm². Panels were mounted on a tracking station and their output was grid connected between testing. Several generations of polymer solar cells and panel constructions were tested in this context to optimize the production of polymer solar panels. Cells lacking a R2R barrier layer were found to degrade due to diffusion of oxygen after less than a month, while R2R encapsulated cells showed around 50% degradation after 6 months but suffered from poor performance due to de-lamination during panel production. A third generation of panels with various barrier layers was produced to optimize the choice of barrier foil and it was found that the inclusion of a thin protective foil between the cell and the barrier foil is critical. The findings provide a preliminary foundation for the production and optimization of large-area polymer solar panels and also enabled a cost analysis of solar panels based on polymer solar cells.

  15. Plasma deposition of polymer composite films incorporating nanocellulose whiskers

    Science.gov (United States)

    Samyn, P.; Airoudj, A.; Laborie, M.-P.; Mathew, A. P.; Roucoules, V.

    2011-11-01

    In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

  16. Modification of Polymer Materials by Ion Bombardment: Case Studies

    International Nuclear Information System (INIS)

    Bielinski, D. M.; Jagielski, J.; Lipinski, P.; Pieczynska, D.; Ostaszewska, U.; Piatkowska, A.

    2009-01-01

    The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

  17. Highly selective single-use fluoride ion optical sensor based on aluminum(III)-salen complex in thin polymeric film

    International Nuclear Information System (INIS)

    Badr, Ibrahim H.A.; Meyerhoff, Mark E.

    2005-01-01

    A highly selective optical sensor for fluoride ion based on the use of an aluminum(III)-salen complex as an ionophore within a thin polymeric film is described. The sensor is prepared by embedding the aluminum(III)-salen ionophore and a suitable lipophilic pH-sensitive indicator (ETH-7075) in a plasticized poly(vinyl chloride) (PVC) film. Optical response to fluoride occurs due to fluoride extraction into the polymer via formation of a strong complex with the aluminum(III)-salen species. Co-extraction of protons occurs simultaneously, with protonation of the indicator dye yielding the optical response at 529 nm. Films prepared using dioctylsebacate (DOS) are shown to exhibit better response (e.g., linear range, detection limit, and optical signal stability) compared to those prepared using ortho-nitrophenyloctyl ether (o-NPOE). Films formulated with aluminum(III)-salen and ETH-7075 indicator in 2 DOS:1 PVC, exhibit a significantly enhanced selectivity for fluoride over a wide range of lipophilic anions including salicylate, perchlorate, nitrate, and thiocyanate. The optimized films exhibit a sub-micromolar detection limit, using glycine-phosphate buffer, pH 3.00, as the test sample. The response times of the fluoride optical sensing films are in the range of 1-10 min depending on the fluoride ion concentration in the sample. The sensor exhibits very poor reversibility owing to a high co-extraction constant (log K = 8.5 ± 0.4), indicating that it can best be employed as a single-use transduction device. The utility of the aluminum(III)-salen based fluoride sensitive films as single-use sensors is demonstrated by casting polymeric films on the bottom of standard polypropylene microtiter plate wells (96 wells/plate). The modified microtiter plate optode format sensors exhibit response characteristics comparable to the classical optode films cast on quartz slides. The modified microtiter is utilized for the analysis of fluoride in diluted anti-cavity fluoride rinse

  18. Removable polytetrafluoroethylene template based epitaxy of ferroelectric copolymer thin films

    Science.gov (United States)

    Xia, Wei; Chen, Qiusong; Zhang, Jian; Wang, Hui; Cheng, Qian; Jiang, Yulong; Zhu, Guodong

    2018-04-01

    In recent years ferroelectric polymers have shown their great potentials in organic and flexible electronics. To meet the requirements of high-performance and low energy consumption of novel electronic devices and systems, structural and electrical properties of ferroelectric polymer thin films are expected to be further optimized. One possible way is to realize epitaxial growth of ferroelectric thin films via removable high-ordered polytetrafluoroethylene (PTFE) templates. Here two key parameters in epitaxy process, annealing temperature and applied pressure, are systematically studied and thus optimized through structural and electrical measurements of ferroelectric copolymer thin films. Experimental results indicate that controlled epitaxial growth is realized via suitable combination of both parameters. Annealing temperature above the melting point of ferroelectric copolymer films is required, and simultaneously moderate pressure (around 2.0 MPa here) should be applied. Over-low pressure (around 1.0 MPa here) usually results in the failure of epitaxy process, while over-high pressure (around 3.0 MPa here) often results in residual of PTFE templates on ferroelectric thin films.

  19. High-Performance Flexible Thin-Film Transistors Based on Single-Crystal-like Silicon Epitaxially Grown on Metal Tape by Roll-to-Roll Continuous Deposition Process.

    Science.gov (United States)

    Gao, Ying; Asadirad, Mojtaba; Yao, Yao; Dutta, Pavel; Galstyan, Eduard; Shervin, Shahab; Lee, Keon-Hwa; Pouladi, Sara; Sun, Sicong; Li, Yongkuan; Rathi, Monika; Ryou, Jae-Hyun; Selvamanickam, Venkat

    2016-11-02

    Single-crystal-like silicon (Si) thin films on bendable and scalable substrates via direct deposition are a promising material platform for high-performance and cost-effective devices of flexible electronics. However, due to the thick and unintentionally highly doped semiconductor layer, the operation of transistors has been hampered. We report the first demonstration of high-performance flexible thin-film transistors (TFTs) using single-crystal-like Si thin films with a field-effect mobility of ∼200 cm 2 /V·s and saturation current, I/l W > 50 μA/μm, which are orders-of-magnitude higher than the device characteristics of conventional flexible TFTs. The Si thin films with a (001) plane grown on a metal tape by a "seed and epitaxy" technique show nearly single-crystalline properties characterized by X-ray diffraction, Raman spectroscopy, reflection high-energy electron diffraction, and transmission electron microscopy. The realization of flexible and high-performance Si TFTs can establish a new pathway for extended applications of flexible electronics such as amplification and digital circuits, more than currently dominant display switches.

  20. Application to the radiation processing of polymer

    Energy Technology Data Exchange (ETDEWEB)

    Yoshii, Fumio [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2003-02-01

    Polypropylene (PP) and biodegradable polymer (blend of poly ({epsilon}-caploracton) 30/polybutylenesuccynate 70), PHB02 were irradiated with an electron beam to improve processability for production of thin film and foam. The processability of the polymer was improved due to enhancement of melt strength with irradiation at the dose range between 10 and 100 kGy. Increase of melt strength is due to entanglement of branch structure formed by irradiation. Possibility of high-speed production of thin film and production of foam have been achieved by this process. The soil degradation test showed that biodegradable polymer film buried in the soil was almost entirely degraded (97%) after two months and completely degraded after two and a half months. In the case of foam samples, 65% degradation was achieved after four months. Radiation crosslinked water-soluble polymer form hydrogel, which absorb much water. The hydrogel prepared by irradiation of polymer in aqueous solution was applied as dressing for healing of wound. In order to evaluate the healing effect of the polyethylene oxide (PEO) hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

  1. Application to the radiation processing of polymer

    International Nuclear Information System (INIS)

    Yoshii, Fumio

    2003-01-01

    Polypropylene (PP) and biodegradable polymer (blend of poly (ε-caploracton) 30/polybutylenesuccynate 70), PHB02 were irradiated with an electron beam to improve processability for production of thin film and foam. The processability of the polymer was improved due to enhancement of melt strength with irradiation at the dose range between 10 and 100 kGy. Increase of melt strength is due to entanglement of branch structure formed by irradiation. Possibility of high-speed production of thin film and production of foam have been achieved by this process. The soil degradation test showed that biodegradable polymer film buried in the soil was almost entirely degraded (97%) after two months and completely degraded after two and a half months. In the case of foam samples, 65% degradation was achieved after four months. Radiation crosslinked water-soluble polymer form hydrogel, which absorb much water. The hydrogel prepared by irradiation of polymer in aqueous solution was applied as dressing for healing of wound. In order to evaluate the healing effect of the polyethylene oxide (PEO) hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

  2. Compositions for directed alignment of conjugated polymers

    Science.gov (United States)

    Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

    2016-04-19

    Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

  3. The influence of the surface topography on the magnetization dynamics in soft magnetic thin films

    NARCIS (Netherlands)

    Craus, CB; Palasantzas, G; Chezan, AR; De Hosson, JTM; Boerma, DO; Niesen, L

    2005-01-01

    In this work we study the influence of surface roughness on the magnetization dynamics of soft magnetic nanocrystalline Fe-Zr-N thin films deposited (under identical conditions) onto a Si oxide, a thin polymer layer, and a thin Cu layer. The substrate temperature during deposition was approximately

  4. Constrained swelling of polymer networks: characterization of vapor-deposited cross-linked polymer thin films

    Czech Academy of Sciences Publication Activity Database

    Dušek, Karel; Choukourov, A.; Dušková-Smrčková, Miroslava; Biederman, H.

    2014-01-01

    Roč. 47, č. 13 (2014), s. 4417-4427 ISSN 0024-9297 R&D Projects: GA ČR GAP101/12/1306 Institutional support: RVO:61389013 Keywords : swelling * cross-linked polymer * elasticity Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.800, year: 2014

  5. 21 CFR 177.1420 - Isobutylene polymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Isobutylene polymers. 177.1420 Section 177.1420... FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1420 Isobutylene polymers. Isobutylene...

  6. Single-step electrospinning to bioactive polymer nanofibers

    Czech Academy of Sciences Publication Activity Database

    Gentsch, R.; Pippig, F.; Schmidt, S.; Černoch, Peter; Polleux, J.; Börner, H. G.

    2011-01-01

    Roč. 44, č. 3 (2011), s. 453-461 ISSN 0024-9297 Institutional research plan: CEZ:AV0Z40500505 Keywords : electrospinning * polymer-peptide conjugate * block copolymer Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.167, year: 2011

  7. Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS

    DEFF Research Database (Denmark)

    Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M.

    2014-01-01

    The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP–β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scat......The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP–β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X...

  8. Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

    Science.gov (United States)

    Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

    2015-02-24

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

  9. End-anchored polymers in good solvents from the single chain limit to high anchoring densities.

    Science.gov (United States)

    Whitmore, Mark D; Grest, Gary S; Douglas, Jack F; Kent, Michael S; Suo, Tongchuan

    2016-11-07

    An increasing number of applications utilize grafted polymer layers to alter the interfacial properties of solid substrates, motivating refinement in our theoretical understanding of such layers. To assess existing theoretical models of them, we have investigated end-anchored polymer layers over a wide range of grafting densities, σ, ranging from a single chain to high anchoring density limits, chain lengths ranging over two orders of magnitude, for very good and marginally good solvent conditions. We compare Monte Carlo and molecular dynamics simulations, numerical self-consistent field calculations, and experimental measurements of the average layer thickness, h, with renormalization group theory, the Alexander-de Gennes mushroom theory, and the classical brush theory. Our simulations clearly indicate that appreciable inter-chain interactions exist at all simulated areal anchoring densities so that there is no mushroom regime in which the layer thickness is independent of σ. Moreover, we find that there is no high coverage regime in which h follows the predicted scaling, h ∼ Nσ 1/3 , for classical polymer brushes either. Given that no completely adequate analytic theory seems to exist that spans wide ranges of N and σ, we applied scaling arguments for h as a function of a suitably defined reduced anchoring density, defined in terms of the solution radius of gyration of the polymer chains and N. We find that such a scaling approach enables a smooth, unified description of h in very good solvents over the full range of anchoring density and chain lengths, although this type of data reduction does not apply to marginal solvent quality conditions.

  10. Electron microscope observation of single - crystalline beryllium thin foils

    International Nuclear Information System (INIS)

    Antolin, J.; Poirier, J.P.; Dupouy, J.M.

    1965-01-01

    Thin foils prepared from single crystalline beryllium simples deformed at room temperature, have been observed by transmission electron microscopy. The various deformation modes have been investigated separately, from their early stages and their characteristic dislocation configurations have been observed. Basal slip is characterized at is outset by the presence of numerous dipoles and elongated prismatic loops. More pronounced cold work leads to the formation of dislocation tangles and bundles which eventually give a cellular structure. Prismatic slip begins by the cross-slip of dislocations from the basal plane into the prismatic plane. A cellular structure is equally observed in heavily deformed samples. Sessile dislocations have been observed in twin boundaries; they are produced by reactions between slip dislocations and twin dislocations. Finally, the study of samples quenched from 1100 deg. C and annealed at 200 deg. C has shown that the observed loops lie in prismatic planes and have a Burgers vector b 1/3 . (authors) [fr

  11. Dynamics and rheology of finitely extensible polymer coils: An overview

    Science.gov (United States)

    Yao, Donggang

    2017-05-01

    One contemporary research issue in non-Newtonian fluid mechanics is to accurately and effectively model viscoelastic polymer flow of practical relevance. In the past several years, we have been working on the formulation of a finitely extensible coil model for polymer flow, particularly including these elements: (1) decoupled equations for kinematical and dynamical variables, (2) logarithmic relaxation at large deformation, (3) rotational retardation, (4) controllable straining, and (5) finite stretch. In this paper, we provide a constructive overview of this nonlinear coil formulation focusing on integration of these elements in a single, unified constitutive model with a minimal number of model parameters that are linked with corresponding physical processes. We also use this opportunity to share the rationale and thought process in the model development. In one particular implement of the general formulation, three parameters are used to tackle with the principal dynamics of a deforming polymer coil: one for finite stretch dictated by a ceiling stretch of the coil, the second one for rotational recovery/retardation, and the third one for adjusting stretch hardening of the rubbery coil. The new model, even in a single mode, is able to simultaneously predict practical material functions in simple shear and coaxial extension and to fit well to representative experimental data. Particularly in the steady-state (or quasi-steady state) flow case, a nearly closed-form stress to velocity gradient relationship can be derived with which shear thinning and elongational thickening can be simultaneously considered while computational advantages of a classical GNF model is retained. The model also fits reasonably well to representative experimental transient data for both shear and extension.

  12. Microscopic theory for dynamics in entangled polymer nanocomposites

    Science.gov (United States)

    Yamamoto, Umi

    New microscopic theories for describing dynamics in polymer nanocomposites are developed and applied. The problem is addressed from two distinct perspectives and using two different theoretical approaches. The first half of this dissertation studies the long-time and intermediate-time dynamics of nanoparticles in entangled and unentangled polymer melts for dilute particle concentrations. Using a combination of mode-coupling, Brownian motion, and polymer physics ideas, the nanoparticle long-time diffusion coefficients is formulated in terms of multiple length-scales, packing microstructures, and spatially-resolved polymer density fluctuation dynamics. The key motional mechanism is described via the parallel relaxation of the force exerted on the particle controlled by collective polymer constraint-release and the particle self-motion. A sharp but smooth crossover from the hydrodynamic to the non-hydrodynamic regime is predicted based on the Stokes-Einstein violation ratio as a function of all the system variables. Quantitative predictions are made for the recovery of the Stokes-Einstein law, and the diffusivity in the crossover regime agrees surprisingly well with large-scale molecular dynamics simulations for all particle sizes and chain lengths studied. The approach is also extended to address intermediate-time anomalous transport of a single nanoparticle and two-particle relative diffusion. The second half of this dissertation focuses on developing a novel dynamical theory for a liquid of infinitely-thin rods in the presence of hard spherical obstacles, aiming at a technical and conceptual extension of the existing paradigm for entangled polymer dynamics. As a fundamental theoretical development, the two-component generalization of a first-principles dynamic meanfield approach is presented. The theory enforces inter-needle topological uncrossability and needlesphere impenetrability in a unified manner, leading to a generalized theory of entanglements that

  13. Fundamental radiation effect on polymers energy transfer from radiation to polymer

    International Nuclear Information System (INIS)

    Seguchi, T.

    2007-01-01

    Polymer modification as cross-link, chain scission, and graft-polymerization by radiation is initiated by the quantum energy transferred from radiation to polymers. The active species for chemical reactions are produced through ionization or activation of polymer molecules for any radiation source. The energy transfer occurs mainly by ionic interaction between radiation and polymer molecule, and the contribution from the collision interaction is miner. The radiation of electromagnetic wave as X-ray or γ-ray generates the energetic electron which induces ionic interaction with polymer molecule. The energy loss profile along the penetration to polymer material is much different among the radiation sources of EB, γ-ray, and ion beams in the macroscopic mechanism. In this article, the behavior of single event, that is, the event induced by one electron, γ-ray, ion, and neutron is described by the macroscopic mechanism and by the microscopic mechanism. (authors)

  14. Perovskite single crystals and thin films for optoelectronic devices (Conference Presentation)

    Science.gov (United States)

    Li, Gang; Han, Qifeng; Yang, Yang; Bae, Sang-Hoon; Sun, Pengyu

    2016-09-01

    Hybrid organolead trihalide perovskite (OTP) solar cells have developed as a promising candidate in photovoltaics due to their excellent properties including a direct bandgap, strong absorption coefficient, long carrier lifetime, and high mobility. Most recently, formamidinium (NH2CH=NH2+ or FA) lead iodide (FAPbI3) has attracted significant attention due to several advantages: (1) the larger organic FA cation can replace the MA cation and form a more symmetric crystal structure, (2) the smaller bandgap of FAPbI3 allows for near infrared (NIR) absorption, and (3) FAPbI3 has an elevated decomposition temperature and thus potential to improve stability. Single crystals provide an excellent model system to study the intrinsic electrical and optical properties of these materials due to their high purity, which is particularly important to understand the limits of these materials. In this work, we report the growth of large ( 5 millimeter size) single crystal FAPbI3 using a novel liquid based crystallization method. The single crystal FAPbI3 demonstrated a δ-phase to α-phase transition with a color change from yellow to black when heated to 185°C within approximately two minutes. The crystal structures of the two phases were identified and the PL emission peak of the α-phase FAPbI3 (820 nm) shows clear red-shift compared to the FAPbI3 thin film (805 nm). The FAPbI3 single crystal shows a long carrier lifetime of 484 ns, a high carrier mobility of 4.4 cm2·V-1·s-1, and even more interestingly a conductivity of 1.1 × 10-7(ohm·cm)-1, which is approximately one order of magnitude higher than that of the MAPbI3 single crystal. Finally, high performance photoconductivity type photodetectors were successfully demonstrated using the single crystal FAPbI3.

  15. Chapter 23. Single and Heterostructure Multiferroic Thin Films

    OpenAIRE

    Barbier , Antoine

    2018-01-01

    International audience; Multiferroic oxide materials exhibiting several long range ferroic orders are of high interest because of their wide range of potential applications. The incorporation of their genuine properties in new devices, offering additional physical properties, requires often elaborating them in form of thin films. Retaining their multiferroic characteristics is very challenging. However, thin films can be structured on the nanometer scale and additional degrees of freedom, suc...

  16. Spectral and time-resolved properties of photoinduced hydroxyquinolines doped thin polymer films

    Science.gov (United States)

    Mehata, Mohan Singh

    2018-01-01

    Quinoline and its derivatives have a wide range of biological and pharmacological activities. Quinoline ring is used to design functional materials (quinoline derivatives) for OLEDs and field-induce electrooptics. It possesses antibacterial, antifungal, antimalarial, cardiotonic, anthelmintic, anti-inflammatory, anticonvulsant and analgesic activity. Here, we have examined photoexcitation dynamics of 6-hydroxyquinoline (6-HQ) doped in polymer films of polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA) and cellulose acetate (CA) at atmospheric conditions. The absorption maximum of 6-HQ in polymer films was observed at 333 ± 1 nm, whereas fluorescence (FL) maximum fell in the range of 365-371 nm. In PVA film, in addition to the typical FL, a band maximum at 432 nm appeared as a result of an excited-state intermolecular proton transfer (ESIPT) reaction facilitated in the hydrogen-bonded complex formed in the ground state between 6-HQ:PVA. The multi-exponential decay behavior of 6-HQ in all the three polymer films indicates a nanoscale heterogeneity of the polymer environments.

  17. Ordered to isotropic morphology transition in pattern-directed dewetting of polymer thin films on substrates with different feature heights.

    Science.gov (United States)

    Roy, Sudeshna; Mukherjee, Rabibrata

    2012-10-24

    Controlled dewetting of a thin polymer film on a topographically patterned substrate is an interesting approach for aligning isotropic dewetted structures. In this article, we investigate the influence of substrate feature height (H(S)) on the dewetting pathway and final pattern morphology by studying the dewetting of polystyrene (PS) thin films on grating substrates with identical periodicity (λ(P) = 1.5 μm), but H(S) varying between 10 nm and 120 nm. We identify four distinct categories of final dewetted morphology, with different extent of ordering: (1) array of aligned droplets (H(S) ≈ 120 nm); (2) aligned undulating ribbons (H(S) ≈ 70-100 nm); (3) multilength scale structures with coexisting large droplets uncorrelated to the substrate and smaller droplets/ribbons aligned along the stripes (H(S) ≈ 40-60 nm); and (4) large droplets completely uncorrelated to the substrate (H(S) dewetted morphologies and transition across categories remain generically unaltered. We finally show that the structures obtained by dewetting on different H(S) substrates exhibits different levels of hydrophobicity because of combined spatial variation of chemical and topographic contrast along the surface. Thus, the work reported in this article can find potential application in fabricating surfaces with controlled wettability.

  18. Positron reemission: measurement of thin single crystal W(100) films to be used as transmission moderator or re-moderators

    International Nuclear Information System (INIS)

    Chen, D.M.; Lynn, K.G.; Pareja, R.; Nielsen, B.

    1984-11-01

    It has been shown that one can produce thin single crystal W films capable of reemitting positrons at a sufficiently high fraction to be used either as a moderator or as a re-moderator. Both the impurities and the defects could be removed by the appropriate cleaning and annealing procedures, and narrow beam emission could be attained when the films were cleaned. This technique would also be a good method for characterizing defect concentration at interfaces or in thin films

  19. Optimized pre-thinning procedures of ion-beam thinning for TEM sample preparation by magnetorheological polishing.

    Science.gov (United States)

    Luo, Hu; Yin, Shaohui; Zhang, Guanhua; Liu, Chunhui; Tang, Qingchun; Guo, Meijian

    2017-10-01

    Ion-beam-thinning is a well-established sample preparation technique for transmission electron microscopy (TEM), but tedious procedures and labor consuming pre-thinning could seriously reduce its efficiency. In this work, we present a simple pre-thinning technique by using magnetorheological (MR) polishing to replace manual lapping and dimpling, and demonstrate the successful preparation of electron-transparent single crystal silicon samples after MR polishing and single-sided ion milling. Dimples pre-thinned to less than 30 microns and with little mechanical surface damage were repeatedly produced under optimized MR polishing conditions. Samples pre-thinned by both MR polishing and traditional technique were ion-beam thinned from the rear side until perforation, and then observed by optical microscopy and TEM. The results show that the specimen pre-thinned by MR technique was free from dimpling related defects, which were still residual in sample pre-thinned by conventional technique. Nice high-resolution TEM images could be acquired after MR polishing and one side ion-thinning. MR polishing promises to be an adaptable and efficient method for pre-thinning in preparation of TEM specimens, especially for brittle ceramics. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Super-resolution fluorescence imaging of nanoimprinted polymer patterns by selective fluorophore adsorption combined with redox switching

    KAUST Repository

    Yabiku, Y.; Kubo, S.; Nakagawa, M.; Vacha, M.; Habuchi, Satoshi

    2013-01-01

    We applied a super-resolution fluorescence imaging based on selective adsorption and redox switching of the fluorescent dye molecules for studying polymer nanostructures. We demonstrate that nano-scale structures of polymer thin films can

  1. Physics of Polymers under Nanoscopic Confinement: a Single Molecule Study

    NARCIS (Netherlands)

    Keshavarz, M.

    2016-01-01

    Physicist Masoumeh Keshavarz studied the thermal motion of a fluorescently labelled, individual “reporter” polymer molecule, surrounded and entangled by a gel of similar but unlabelled polymers. Owing to their extreme length and stiffness, it is possible to follow the shape and the motion of the

  2. General Space-Confined On-Substrate Fabrication of Thickness-Adjustable Hybrid Perovskite Single-Crystalline Thin Films.

    Science.gov (United States)

    Chen, Yao-Xuan; Ge, Qian-Qing; Shi, Yang; Liu, Jie; Xue, Ding-Jiang; Ma, Jing-Yuan; Ding, Jie; Yan, Hui-Juan; Hu, Jin-Song; Wan, Li-Jun

    2016-12-21

    Organic-inorganic hybrid perovskite single-crystalline thin films (SCTFs) are promising for enhancing photoelectric device performance due to high carrier mobility, long diffusion length, and carrier lifetime. However, bulk perovskite single crystals available today are not suitable for practical device application due to the unfavorable thickness. Herein, we report a facile space-confined solution-processed strategy to on-substrate grow various hybrid perovskite SCTFs in a size of submillimeter with adjustable thicknesses from nano- to micrometers. These SCTFs exhibit photoelectric properties comparable to bulk single crystals with low defect density and good air stability. The clear thickness-dependent colors allow fast visual selection of SCTFs with a suitable thickness for specific device application. The present substrate-independent growth of perovskite SCTFs opens up opportunities for on-chip fabrication of diverse high-performance devices.

  3. Multiscale Modeling at Nanointerfaces: Polymer Thin Film Materials Discovery via Thermomechanically Consistent Coarse Graining

    Science.gov (United States)

    Hsu, David D.

    Due to high nanointerfacial area to volume ratio, the properties of "nanoconfined" polymer thin films, blends, and composites become highly altered compared to their bulk homopolymer analogues. Understanding the structure-property mechanisms underlying this effect is an active area of research. However, despite extensive work, a fundamental framework for predicting the local and system-averaged thermomechanical properties as a function of configuration and polymer species has yet to be established. Towards bridging this gap, here, we present a novel, systematic coarse-graining (CG) method which is able to capture quantitatively, the thermomechanical properties of real polymer systems in bulk and in nanoconfined geometries. This method, which we call thermomechanically consistent coarse-graining (TCCG), is a two-bead-per-monomer CG hybrid approach through which bonded interactions are optimized to match the atomistic structure via the Iterative Boltzmann Inversion method (IBI), and nonbonded interactions are tuned to macroscopic targets through parametric studies. We validate the TCCG method by systematically developing coarse-grain models for a group of five specialized methacrylate-based polymers including poly(methyl methacrylate) (PMMA). Good correlation with bulk all-atom (AA) simulations and experiments is found for the temperature-dependent glass transition temperature (Tg) Flory-Fox scaling relationships, self-diffusion coefficients of liquid monomers, and modulus of elasticity. We apply this TCCG method also to bulk polystyrene (PS) using a comparable coarse-grain CG bead mapping strategy. The model demonstrates chain stiffness commensurate with experiments, and we utilize a density-correction term to improve the transferability of the elastic modulus over a 500 K range. Additionally, PS and PMMA models capture the unexplained, characteristically dissimilar scaling of Tg with the thickness of free-standing films as seen in experiments. Using vibrational

  4. PEDOT as a Flexible Organic Electrode for a Thin Film Acoustic Energy Harvester.

    Science.gov (United States)

    Kim, Younghoon; Na, Jongbeom; Park, Chihyun; Shin, Haijin; Kim, Eunkyoung

    2015-08-05

    An efficient thin film acoustic energy harvester was explored using flexible poly(3,4-ethylene dioxythiophene) (PEDOT) films as electrodes in an all-organic triboelectric generator (AO-TEG). A thin film AO-TEG structured as PEDOT/Kapton//PET/PEDOT was prepared by the solution casting polymerization(SCP) on the dielectric polymer films. As-prepared AO-TEG showed high flexibility and durability due to the strong adhesion between the electrodes and the dielectric polymer. The short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum power density (Pw) reached 50 mA/m(2), 700 V, and 12.9 W/m(2) respectively. The output current density decreased with the increase in the electrode resistance (Re), but the energy loss in the organic electrodes was negligible. The AO-TEG could light up 180 LEDs instantaneously upon touching of the AO-TEG with a palm (∼120 N). With the flexible structure, the AO-TEG was worn as clothes and generated electricity to light LEDs upon regular human movement. Furthermore, the AO-TEG was applicable as a thin film acoustic energy harvester, which used music to generate electricity enough for powering of 5 LEDs. An AO-TEG with a PEDOT electrode (Re = 200 Ω) showed instantaneous peak-to-peak voltage generation of 11 V under a sound pressure level (SPL) of 90-100 dB. The harvested acoustic energy through the AO-TEG was 350 μJ from the 4 min playing of the same single song. This is the first demonstration of a flexible triboelectric generator (TEG) using an organic electrode for harvesting acoustic energy from ambient environment.

  5. Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers.

    Science.gov (United States)

    Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J; Sforazzini, Giuseppe; Anderson, Harry L; Pullerits, Tõnu; Scheblykin, Ivan G

    2015-10-19

    Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

  6. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    International Nuclear Information System (INIS)

    Chang, Yung-Ting; Liu, Shun-Wei; Yuan, Chih-Hsien; Lee, Chih-Chien; Ho, Yu-Hsuan; Wei, Pei-Kuen; Chen, Kuan-Yu; Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti; Wu, Chih-I

    2013-01-01

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts

  7. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yung-Ting [Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Taiwan (China); Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan (China); Liu, Shun-Wei [Department of Electronic Engineering, Mingchi University of Technology, New Taipei, Taiwan 24301, Taiwan (China); Yuan, Chih-Hsien; Lee, Chih-Chien [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 10607, Taiwan (China); Ho, Yu-Hsuan; Wei, Pei-Kuen [Research Center for Applied Science Academia Sinica, Taipei, Taiwan 11527, Taiwan (China); Chen, Kuan-Yu [Chilin Technology Co., LTD, Tainan City, Taiwan 71758, Taiwan (China); Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti, E-mail: cchen@chem.sinica.edu.tw, E-mail: chihiwu@cc.ee.ntu.edu.tw [Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Taiwan (China); Wu, Chih-I, E-mail: cchen@chem.sinica.edu.tw, E-mail: chihiwu@cc.ee.ntu.edu.tw [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan (China)

    2013-11-07

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.

  8. Formation of SmFe{sub 5}(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: yabuhara@futamoto.elect.chuo-u.ac.j [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2010-01-01

    SmFe{sub 5}(0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe{sub 5} structure forming an alloy compound of Sm(Fe,Cu){sub 5}. The Sm(Fe,Cu){sub 5} film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  9. Characterization of boron nitride thin films prepared from a polymer precursor

    International Nuclear Information System (INIS)

    Chan, V.Z.; Rothman, J.B.; Palladino, P.; Sneddon, L.G.; Composto, R.J.

    1996-01-01

    Excellent quality boron nitride (BN) thin films on silicon have been produced by a simple procedure involving spincoating solutions of the open-quote open-quote single-source close-quote close-quote polymeric-precursor polyborazylene, (B 3 N 3 H ∼4 ) x , on a silicon substrate, followed by pyrolysis at 900 degree C. Rutherford backscattering spectrometry (RBS) indicates that the B/N ratios are 1.37 and 1.09 for conversions carried out in a vacuum oven at 900 and 1250 degree C, respectively. Forward recoil spectrometry (FRES) showed that the atomic percent of residual hydrogen is 10 and 9%, respectively. Plain-view and cross-sectional scanning electron microscopy (SEM) studies showed that the samples annealed at 900 degree C were clean and uniform in thickness. A thickness of 800x10 15 atoms/cm 2 was determined by ion scattering. Films annealed to 1250 degree C likewise showed a continuous unbroken boron nitride layer, but also exhibited morphological features resulting from reactions of the underlying silicon oxide-silicon interface in the substrate. Auger electron spectroscopy and atomic force microscopy showed that the BN coating produced at this higher temperature remained unbroken but had a surface area of ∼15% covered by dimples 2 endash 7 nm in depth. Compared to typical films made by chemical vapor deposition, BN films produced from this open-quote open-quote single-source close-quote close-quote method have lower hydrogen and carbon concentrations. copyright 1996 Materials Research Society

  10. Heating of polymer substrate by discharge plasma in radiofrequency magnetron sputtering deposition

    International Nuclear Information System (INIS)

    Sirghi, Lucel; Popa, Gheorghe; Hatanaka, Yoshinori

    2006-01-01

    The substrate used for the thin film deposition in a radiofrequency magnetron sputtering deposition system is heated by the deposition plasma. This may change drastically the surface properties of the polymer substrates. Deposition of titanium dioxide thin films on polymethyl methacrylate and polycarbonate substrates resulted in buckling of the substrate surfaces. This effect was evaluated by analysis of atomic force microscopy topography images of the deposited films. The amount of energy received by the substrate surface during the film deposition was determined by a thermal probe. Then, the results of the thermal probe measurements were used to compute the surface temperature of the polymer substrate. The computation revealed that the substrate surface temperature depends on the substrate thickness, discharge power and substrate holder temperature. For the case of the TiO 2 film depositions in the radiofrequency magnetron plasma, the computation indicated substrate surface temperature values under the polymer melting temperature. Therefore, the buckling of polymer substrate surface in the deposition plasma may not be regarded as a temperature driven surface instability, but more as an effect of argon ion bombardment

  11. A study on the life extension of polymer materials under radiation environment

    International Nuclear Information System (INIS)

    Park, K. J; Park, S. W.; Jung, K. S.; Cho, S. H.; Seo, H. S.

    2001-12-01

    The object of this project is to improve the stability and the economics by reducing the radiation-induced oxidation as a factor of degradation of polymer materials used under the radiation environment. In order to attain the objective of this study and to check the effect of diamond-like carbon(DLC) coating on the anti-oxidation reaction, polymer specimens such as ABS, Acryl, Polycarbonate, Polyethylene, Polypropylene, PVC coating DLC thin layer were exposed to high-level gamma radiation, and their irradiation effects were investigated. A plasma-enhanced chemical vapor deposition method was adopted in fabricating a DLC thin film on the polymer specimens, which were irradiated with the non-DLC film deposited specimens under the gamma radiation emitted from Co-60 source from 1x10 5 to 1x10 8 rads exposure. According to the characterization of irradiated specimens from the elapsed time of minimum 4 hours to a maximum of 105 days after the irradiation, the DLC deposition on the polymer surface was revealed to contribute to the improvement on the resistance of the radiation-induced oxidation in this study

  12. Detection of radiation deformation in crystalline polymers using the speckle photography technique

    International Nuclear Information System (INIS)

    El-Ghandoor, H.; Hashem, A.A.; Sharaf, F.

    1995-01-01

    In order to measure the resulting deformation due to gamma irradiation of polymers, a new optical technique, namely speckle-photography, was established and used. Thin films of tetrafluoroethene, with constant thickness were irradiated by different doses of gamma rays and the diffraction patterns of a laser beam passing through these films were recorded using the speckle photography technique. This technique has been applied to detect the radiation deformation in (Teflon) TFE, which is a crystalline polymer. A diffraction pattern due to the TFE thin layer is obtained and superimposed on the interference pattern displaying the speckle pattern pairs recorded on the same emulsion. (author)

  13. Manufacture of Bi-cuprate thin films on MgO single crystal substrates by chemical solution deposition

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Bertelsen, Christian Vinther; Andersen, Niels Hessel

    2014-01-01

    Bi2Sr2CaCu2O8 thin films have been deposited on MgO single crystal substrates by spin-coating a solution based on 2-ethylhexanoate precursors dissolved in xylene. Pyrolysis takes place between 200°C and 450°C and is accompanied by the release of 2-ethylhexanoic acid, CO2 and H2O vapour. Highly c...

  14. Improving information density in ferroelectric polymer films by using nanoimprinted gratings

    Science.gov (United States)

    Martínez-Tong, Daniel E.; Soccio, Michela; Rueda, Daniel R.; Nogales, Aurora; García-Gutiérrez, Mari Cruz; Ezquerra, Tiberio A.

    2015-03-01

    The development of polymer non-volatile memories depends on the effective fabrication of devices with high density of information. Well-defined low aspect ratio nanogratings on thin films of poly(vinylidene fluoride-trifluoroethylene) copolymers can be fabricated by using Nanoimprint Lithography (NIL). By using these nanogratings, an improved management of writing and reading information can be reached as revealed by Piezoresponse Force Microscopy (PFM). Structural investigation by means of Grazing Incidence X-ray (GIX) scattering techniques indicates that the physical confinement generated by nanoimprint promotes the development of smaller and edge-on oriented crystals. Our results evidence that one-dimensional nanostructuring can be a straightforward approach to improve the control of the polarization in ferroelectric polymer thin films.

  15. Hybrid Photonic Integration on a Polymer Platform

    Directory of Open Access Journals (Sweden)

    Ziyang Zhang

    2015-09-01

    Full Text Available To fulfill the functionality demands from the fast developing optical networks, a hybrid integration approach allows for combining the advantages of various material platforms. We have established a polymer-based hybrid integration platform (polyboard, which provides flexible optical input/ouptut interfaces (I/Os that allow robust coupling of indium phosphide (InP-based active components, passive insertion of thin-film-based optical elements, and on-chip attachment of optical fibers. This work reviews the recent progress of our polyboard platform. On the fundamental level, multi-core waveguides and polymer/silicon nitride heterogeneous waveguides have been fabricated, broadening device design possibilities and enabling 3D photonic integration. Furthermore, 40-channel optical line terminals and compact, bi-directional optical network units have been developed as highly functional, low-cost devices for the wavelength division multiplexed passive optical network. On a larger scale, thermo-optic elements, thin-film elements and an InP gain chip have been integrated on the polyboard to realize a colorless, dual-polarization optical 90° hybrid as the frontend of a coherent receiver. For high-end applications, a wavelength tunable 100Gbaud transmitter module has been demonstrated, manifesting the joint contribution from the polyboard technology, high speed polymer electro-optic modulator, InP driver electronics and ceramic electronic interconnects.

  16. Efficient sampling of reversible cross-linking polymers: Self-assembly of single-chain polymeric nanoparticles

    Science.gov (United States)

    Oyarzún, Bernardo; Mognetti, Bortolo Matteo

    2018-03-01

    We present a new simulation technique to study systems of polymers functionalized by reactive sites that bind/unbind forming reversible linkages. Functionalized polymers feature self-assembly and responsive properties that are unmatched by the systems lacking selective interactions. The scales at which the functional properties of these materials emerge are difficult to model, especially in the reversible regime where such properties result from many binding/unbinding events. This difficulty is related to large entropic barriers associated with the formation of intra-molecular loops. In this work, we present a simulation scheme that sidesteps configurational costs by dedicated Monte Carlo moves capable of binding/unbinding reactive sites in a single step. Cross-linking reactions are implemented by trial moves that reconstruct chain sections attempting, at the same time, a dimerization reaction between pairs of reactive sites. The model is parametrized by the reaction equilibrium constant of the reactive species free in solution. This quantity can be obtained by means of experiments or atomistic/quantum simulations. We use the proposed methodology to study the self-assembly of single-chain polymeric nanoparticles, starting from flexible precursors carrying regularly or randomly distributed reactive sites. We focus on understanding differences in the morphology of chain nanoparticles when linkages are reversible as compared to the well-studied case of irreversible reactions. Intriguingly, we find that the size of regularly functionalized chains, in good solvent conditions, is non-monotonous as a function of the degree of functionalization. We clarify how this result follows from excluded volume interactions and is peculiar of reversible linkages and regular functionalizations.

  17. Polymer architecture and drug delivery.

    Science.gov (United States)

    Qiu, Li Yan; Bae, You Han

    2006-01-01

    Polymers occupy a major portion of materials used for controlled release formulations and drug-targeting systems because this class of materials presents seemingly endless diversity in topology and chemistry. This is a crucial advantage over other classes of materials to meet the ever-increasing requirements of new designs of drug delivery formulations. The polymer architecture (topology) describes the shape of a single polymer molecule. Every natural, seminatural, and synthetic polymer falls into one of categorized architectures: linear, graft, branched, cross-linked, block, star-shaped, and dendron/dendrimer topology. Although this topic spans a truly broad area in polymer science, this review introduces polymer architectures along with brief synthetic approaches for pharmaceutical scientists who are not familiar with polymer science, summarizes the characteristic properties of each architecture useful for drug delivery applications, and covers recent advances in drug delivery relevant to polymer architecture.

  18. Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

    International Nuclear Information System (INIS)

    Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-01-01

    FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe 50 Co 50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal

  19. Injection molded polymer chip for electrochemical and electrophysiological recordings from single cells

    DEFF Research Database (Denmark)

    Tanzi, Simone; Larsen, Simon Tylsgaard; Taboryski, Rafael J.

    We present a novel method to fabricate an all in polymer injection molded chip for electrochemical cell recordings and lateral cell trapping. The complete device is molded in thermoplastic polymer and it results from assembling two halves. We tested spin-coated conductive polymer poly(3,4-ethylen...

  20. Fabrication and characterization of shape memory polymers at small-scales

    Science.gov (United States)

    Wornyo, Edem

    The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory polymers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) Design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) Utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) Utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) Study spin coating conditions on thin film quality with designed experiments. (iv) Apply neural networks and genetic algorithms to optimize these systems.