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Sample records for block copolymers influence

  1. Influence of polydispersity on the phase behavior of statistical multiblock copolymers with Schultz-Zimm block molecular weight distributions

    NARCIS (Netherlands)

    Angerman, H.J.; Brinke, G. ten; Slot, J.J.M.

    1999-01-01

    In this paper we investigate in a systematic way the influence of polydispersity in the block lengths on the phase behavior of AB-multiblock copolymer melts. As model system we take a polydisperse multiblock copolymer for which both the A-blocks and the B-blocks satisfy a Schultz-Zimm distribution.

  2. Synthesis of manganese oxide supported on mesoporous titanium oxide: Influence of the block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Schmit, F. [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon (UMR 5256 CNRS/Université Lyon 1), Lyon (France); Bois, L., E-mail: laurence.bois@univ-lyon1.fr [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); Chiriac, R.; Toche, F.; Chassagneux, F. [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); Besson, M.; Descorme, C. [IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon (UMR 5256 CNRS/Université Lyon 1), Lyon (France); Khrouz, L. [ENS LYON Laboratoire de Chimie (LR6, site Monod), 46, allée d’Italie, 69364 Lyon Cedex 07 (France)

    2015-01-15

    Manganese oxides supported on mesoporous titanium oxides were synthesized via a sol–gel route using block copolymer self-assembly. The oxides were characterized by X-ray diffraction, infrared spectroscopy, thermal analyses, nitrogen adsorption/desorption, electron microscopy and electronic paramagnetic resonance. A mesoporous anatase containing amorphous manganese oxide particles could be obtained with a 0.2 Mn:Ti molar ratio. At higher manganese loading (0.5 Mn:Ti molar ratio), segregation of crystalline manganese oxide occurred. The influence of block copolymer and manganese salt on the oxide structure was discussed. The evolution of the textural and structural characteristics of the materials upon hydrothermal treatment was also investigated. - Graphical abstract: One-pot amorphous MnO{sub 2} supported on mesoporous anataseTiO{sub 2}. - Highlights: • Mesoporous manganese titanium oxides were synthesized using block copolymer. • Block copolymers form complexes with Mn{sup 2+} from MnCl{sub 2}. • With block copolymer, manganese oxide can be dispersed around the titania crystallites. • With Mn(acac){sub 2}, manganese is dispersed inside titania. • MnOOH crystallizes outside mesoporous titania during hydrothermal treatment.

  3. Photoinduced optical anisotropy in azobenzene methacrylate block copolymers: Influence of molecular weight and irradiation conditions

    DEFF Research Database (Denmark)

    Gimeno, Sofia; Forcen, Patricia; Oriol, Luis;

    2009-01-01

    The photoinduced anisotropy in a series of azomethacrylate block copolymers with different Molecular weights and azo contents has been investigated under several irradiation conditions. Depending on molecular weight and composition, different microstructures (disordered, lamellar, spherical) appear...... the copolymers in which azobenzene units segregate to nano spheres and the lowest (and less stable) Delta n(N) values, appear in disordered systems not showing any defined microstructure. Besides, higher Delta n(N) is obtained in the copolymers with larger molecular weight of the poly (methyl......) and light power (from 100 to 500 mW/cm(2)) also influence the photoinduced response. Photoinduced Delta n(N) growth rate is faster when both temperature and irradiation power increase. Furthermore, birefringence is only induced at temperatures up to 90 degrees C, the maximum value being obtained at...

  4. Synthesis of manganese oxide supported on mesoporous titanium oxide: Influence of the block copolymer

    Science.gov (United States)

    Schmit, F.; Bois, L.; Chiriac, R.; Toche, F.; Chassagneux, F.; Besson, M.; Descorme, C.; Khrouz, L.

    2015-01-01

    Manganese oxides supported on mesoporous titanium oxides were synthesized via a sol-gel route using block copolymer self-assembly. The oxides were characterized by X-ray diffraction, infrared spectroscopy, thermal analyses, nitrogen adsorption/desorption, electron microscopy and electronic paramagnetic resonance. A mesoporous anatase containing amorphous manganese oxide particles could be obtained with a 0.2 Mn:Ti molar ratio. At higher manganese loading (0.5 Mn:Ti molar ratio), segregation of crystalline manganese oxide occurred. The influence of block copolymer and manganese salt on the oxide structure was discussed. The evolution of the textural and structural characteristics of the materials upon hydrothermal treatment was also investigated.

  5. Bactericidal block copolymer micelles.

    Science.gov (United States)

    Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo

    2011-05-12

    Block copolymer micelles with bactericidal properties were designed to deactivate pathogens such as E. coli bacteria. The micelles of PS-b-PAA and PS-b-P4VP block copolymers were loaded with biocides TCMTB or TCN up to 20 or 30 wt.-%, depending on the type of antibacterial agent. Bacteria were exposed to loaded micelles and bacterial deactivation was evaluated. The micelles loaded with TCN are bactericidal; bacteria are killed in less than two minutes of exposure. The most likely interpretation of the data is that the biocide is transferred to the bacteria by repeated micelle/bacteria contacts, and not via the solution. PMID:21275041

  6. Block copolymer battery separator

    Energy Technology Data Exchange (ETDEWEB)

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  7. Bottlebrush Copolymer Morphology Transition: Influence of Side Chain Length and Block Volume Fraction

    Science.gov (United States)

    Gai, Yue; Song, Dong-Po; Watkins, James

    Brush block copolymers synthesized via living ring-opening metathesis polymerization (ROMP) offer unique advantages as templates for functional hybrid materials. Unlike linear block copolymer, the bottlebrush polymer phase transition not only depends on volume fractions of the two blocks but also on side chain length. Here we report the morphology transitions of PS-b-PEO bottlebrush copolymer (BBCP) as a function of PEO side chain length and block volume fraction. For the BBCPs with similar side chain lengths, highly ordered lamellar morphologies were observed with PEO volume fractions in a wide range from 32 vol% to 72 vol%, which is significantly different from that of traditional linear block copolymers. This study will lay the groundwork for nanostructure fabrications using the BBCPs and provides new insights into the phase behavior of the new type of materials. This work was supported by NSF center for Hierarchical Manufacturing at the University of Massachusetts, Amherst.

  8. How the chemical structure influence the dynamics of association of amphiphilic block copolymers

    Czech Academy of Sciences Publication Activity Database

    Deniau-Lejeune, E.; Charbonneau, C.; Borisova, O.; Chassenieux, C.; Colombani, O.; Štěpánek, Petr; Borisov, O.

    Saint-Petersburg: Institute of Macromolecular Compounds RAS, 2014. s. 46. ISBN 978-5-98340-329-1. [International Symposium "Molecular Order and Mobility in Polymer Systems" /8./. 02.06.2014-06.06.2014, St. Petersburg] Institutional support: RVO:61389013 Keywords : block copolymer * nanoparticles Subject RIV: CD - Macromolecular Chemistry

  9. Influencing the structure of block copolymer micelles with small molecule additives

    Science.gov (United States)

    Robertson, Megan; Singh, Avantika; Cooksey, Tyler; Kidd, Bryce; Piemonte, Rachele; Wang, Shu; Mai Le, Kim; Madsen, Louis

    Amphiphilic block copolymer micelles in water are under broad exploration for drug delivery applications due to their high loading capacity and targeted drug delivery. We aim to understand the kinetic and thermodynamic processes that underlie the self-assembly of diblock copolymer micelle systems. The present work focuses on diblock copolymers containing poly(ethylene oxide) (a hydrophilic polymer) and polycaprolactone (a hydrophobic polymer), which spontaneously self-assemble into spherical micelles in water. Addition of a common good solvent (a co-solvent) for both of the constituting blocks, such as tetrahydrofuran (THF), reduces the interfacial tension at the core-corona interface. We are currently investigating the effect of this phenomenon on the micelle structural properties, using small-angle scattering and nuclear magnetic resonance. We have characterized the hydrodynamic radius, core radius, corona thickness, aggregation number, degree of swelling of the micelle core with the co-solvent, and unimer (free chain) concentration, as a function of the co-solvent concentration. Fundamental knowledge from these studies will inform design of drug delivery systems by allowing us to tailor micelle properties for optimal cargo loading.

  10. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

  11. The influence of incompatibility and dielectric contrast on the electric field-induced orientation of lamellar block copolymers

    International Nuclear Information System (INIS)

    We investigate the influence of incompatibility and dielectric contrast on the reorientation kinetics of concentrated solutions of lamellar block copolymers in the presence of an external DC electric field. We study solutions of AC diblock copolymer and ABC triblock terpolymers. The inclusion of a short, polar middle block B is used to tailor both the degree of incompatibility and the dielectric contrast between the two majority phases. In situ synchrotron radiation small-angle X-ray scattering is used to monitor the reorientation process. For the AC diblock copolymer sample only weak electric field induced reorientation could be achieved, following a very slow kinetics, whereas for the ABC triblock terpolymer, reorientation is observed above a threshold value of 0.3 kV/mm. The orientation kinetics is well described by a single exponential with characteristic time constants varying between a few seconds and several minutes depending on the polymer concentration and the electric field strength. We identify a narrow concentration window, in which the interplay between chain mobility and gain in free energy in the electric field allows the preparation of highly anisotropic bulk polymer samples by exposure to an electric field. The results are compared to free energy calculations revealing a distinct difference in the driving force for reorientation as a consequence of an increase in dielectric contrast and chain mobility upon introduction of the B middle block.

  12. Rheological and Mechanical behaviour of Block copolymers, Multigraft copolymers and Block copolymer Nanocomposites

    OpenAIRE

    Thunga, Mahendra

    2009-01-01

    Block copolymers are commercially significant and fundamentally interesting class of polymeric materials. The ability to undergo interfacial thermodynamics-controlled microphase separation from a completely disordered state in the melt to a specifically defined ordered structure through self-organization makes the block copolymers based materials unique. Block copolymer are strongly replacing many of the commercially available polymers due to their unique microstructure and properties. The mo...

  13. NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Guojun Liu

    2000-01-01

    Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, selfassembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films with nanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisopreneblock-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannels were formed by extracting out hPtBA with solvent. Alternatively, larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeability constants ~6 orders of magnitude higher than that of low-density polyethylene films.

  14. Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

    Institute of Scientific and Technical Information of China (English)

    WU Ming-hua; LIN He-ming

    2008-01-01

    Polyester polyether block copolymer (PPBC) was synthesized by ester-exchange and polycodensation reactions using dimethyl terephthalate (DMT), ethylene glycol (EG) and polyethylene glycol (PEG) as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG (nDMT/nPEG), temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration (CMC) of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC'S surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows: PEG molecular weight is 1500, mol ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260°C×1h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.

  15. Interfaces between Block Copolymer Domains

    Science.gov (United States)

    Kim, Jaeup; Jeong, Seong-Jun; Kim, Sang Ouk

    2011-03-01

    Block copolymers naturally form nanometer scale structures which repeat their geometry on a larger scale. Such a small scale periodic pattern can be used for various applications such as storage media, nano-circuits and optical filters. However, perfect alignment of block copolymer domains in the macroscopic scale is still a distant dream. The nanostructure formation usually occurs with spontaneously broken symmetry; hence it is easily infected by topological defects which sneak in due to entropic fluctuation and incomplete annealing. Careful annealing can gradually reduce the number of defects, but once kinetically trapped, it is extremely difficult to remove all the defects. One of the main reasons is that the defect finds a locally metastable morphology whose potential depth is large enough to prohibit further morphology evolution. In this work, the domain boundaries between differently oriented lamellar structures in thin film are studied. For the first time, it became possible to quantitatively study the block copolymer morphology in the transitional region, and it was shown that the twisted grain boundary is energetically favorable compared to the T-junction grain boundary. [Nano Letters, 9, 2300 (2010)]. This theoretical method successfully explained the experimental results.

  16. Micellization and Dynamics of a Block Copolymer

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2006-01-01

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block length...... copolymer mixtures, and evidence in favor of a multi-equilibria unimer-micelle model will be presented. Results obtained by liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect...

  17. Multicompartment Micelles From π-Shaped ABC Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHONG Chong-Li

    2007-01-01

    Dissipative particle dynamics simulations were performed on the morphology and structure of multicompartment micelles formed from n-shaped ABC block copolymers in water. The influences of chain architectures were studied in a systematic way, and a rich variety of morphologies were observed, such as spherical, wormlike,X-shaped, Y-shaped, ribbon-like, layered rod-like, layered disk-like, as well as network morphologies. The simulations show that the distance between the two grafts plays an important role in control of the morphology. Since π-shaped ABC block copolymers can be reduced to linear ABC and star ABC block copolymers, they are good model copolymers for studying the self-assembly of complex block copolymers into micelles. The knowledge obtained in this work as well as the new morphologies identified provide useful information for future rational design and synthesis of novel multicompartment micelles.

  18. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems ...

  19. STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    DING Youjun; QI Daquan

    1988-01-01

    Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block copolymers was calculated from the intensities of their proton signals in 1H NMR spectra and lies in the region of 0 < B < 1. It was shown that the degree of randomness (B) and the average sequence length (L) in block copolymers were relatively dependent on the reaction conditions, various feed ratios and structure of diols.The phenomenon was observed, when the PSF-PEs block copolymers dissolved in different solvents they had different viscosities and molecular conformations.The PSF-PEs block copolymers had better solvent resistance than homo-polysulfone.

  20. Self-assembly of block copolymers

    Directory of Open Access Journals (Sweden)

    Hidenori Otsuka

    2001-05-01

    Full Text Available Block copolymers in a selective solvent have a tendency to self-assemble at surfaces and into micelles1–4. At an aqueous interface, the amphiphilic property of block copolymers composed of hydrophilic and hydrophobic segments can cause the distal end of the hydrophilic chain to extend into the bulk aqueous solution, anchoring the hydrophilic block to the substrate surface through hydrophobic segments1, 2. In an aqueous solution, micelles with core-shell structure are formed by the segregation of insoluble blocks into the core, which is surrounded by a hydrophilic shell composed of hydrophilic blocks3, 4. This interfacial activity of amphiphilic block copolymers provides their utility in the biomedical field as colloidal dispersants, surface modifiers and drug carriers, prompting many studies of block copolymer adsorption on solid surfaces5, 6, 7, 8, force measurements between tethered layers9, 10, 11 and the characterization of micelle properties12, 13, 14.

  1. Functional Nanoporous Polymers from Block Copolymer Precursors

    OpenAIRE

    Guo, Fengxiao

    2010-01-01

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and...

  2. Photo-Induced Micellization of Block Copolymers

    OpenAIRE

    Satoshi Kuwayama; Eri Yoshida

    2010-01-01

    We found novel photo-induced micellizations through photolysis, photoelectron transfer, and photo-Claisen rearrangement. The photolysis-induced micellization was attained using poly(4-tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). BSt-b-PSt showed no self-assembly in dichloromethane and existed as isolated copolymers. Dynamic light scattering demonstrated that the copolymer produced spherical micelles in this solvent due to irradiation with a high-pressure mercury lamp ...

  3. Block Copolymer Membranes for Biofuel Purification

    Science.gov (United States)

    Evren Ozcam, Ali; Balsara, Nitash

    2012-02-01

    Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

  4. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.

    Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems of...... such PEG-based block copolymers in aqueous suspensions are reviewed. Based on scattering experiments using either X-ray or neutrons, the phase behavior is characterized, showing that the thermo-reversible gelation is a result of micellar ordering into mesoscopic crystalline phases of cubic, hexagonal...

  5. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed......Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential......, where living anionic polymerization and atom transfer radical polymerization (ATRP) are combined to synthesize a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer precursor. By using either anhydrous hydrogen fluoride or trifluoroacetic acid, PtBA block...

  6. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  7. Comparing Fluid and Elastic Block Copolymer Shells

    Science.gov (United States)

    Rozairo, Damith; Croll, Andrew B.

    2014-03-01

    Emulsions can be stabilized with the addition of an amphiphilic diblock copolymer, resulting in droplets surrounded and protected by a polymer monolayer. Such droplets show considerable promise as advanced cargo carriers in pharmaceuticals or cosmetics due to their strength and responsiveness. Diblock copolymer interfaces remain mostly fluid and may not be able to attain the mechanical performance desired by industry. To strengthen block copolymer emulsion droplets we have developed a novel method for creating thin elastic shells using polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS). Characterization of the fluid filled elastic shells is difficult with traditional means which lead us to develop a new and general method of mechanical measurement. Specifically, we use laser scanning confocal microscopy to achieve a high resolution measure of the deformation of soft spheres under the influence of gravity. To prove the resilience of the technique we examine both a polystyrene-b-poly(ethylene oxide) (PS-PEO) stabilized emulsion and the PS-PAA-PS emulsion. The mechanical measurement allows the physics of the polymer at the interface to be examined, which will ultimately lead to the rational development of these technologies.

  8. Rapid self-assembly of block copolymers to photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  9. Micellization and Characterization of Block Copolymer Detergents

    DEFF Research Database (Denmark)

    Hvidt, Søren

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes...... depending on block length ratios and temperature. The micellization process with increasing temperature or concentration has been followed by a number of techniques including differential scanning calorimetry and surface tension measurements. The detailed micellar mechanism is not well understood and...... different models have been proposed. Results obtained by a range of liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect the presence of impurities....

  10. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    Science.gov (United States)

    Hoarfrost, Megan Lane

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture

  11. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars;

    2016-01-01

    simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale. PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are directly applied on substrates including polymers, silicon and graphene. A single oxygen......Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly...... plasma treatment enables formation of the oxidized PDMS hard mask, PS block removal and polymer or graphene substrate patterning....

  12. Thermodynamic Interactions in Organometallic Block Copolymers

    International Nuclear Information System (INIS)

    The thermodynamic interactions in anionically synthesized poly(styrene-block-ferrocenyldimethylsilane) (SF) copolymers were examined using birefringence, small angle X-ray and neutron scattering (SAXS and SANS). We show that birefringence detection of the order-disorder transition is possible in colored samples provided the wavelength of the incident beam is in the tail of the absorption spectrum. The location of the order-disorder transition was confirmed by SAXS. The temperature-dependence of the Flory-Huggins parameter, χ, of SF copolymers, determined by SAXS, is similar in magnitude to that between polystyrene and polyisoprene chains. We find that χ is independent of block copolymer composition (within experimental error). We also demonstrate that the neutron scattering length densities of styrene and ferrocenyldimethylsilane moieties are identical due to a surprising cancellation of factors related to density and atomic composition

  13. Design of block copolymer membranes using segregation strength trend lines

    KAUST Repository

    Sutisna, Burhannudin

    2016-05-18

    Block copolymer self-assembly and non-solvent induced phase separation are now being combined to fabricate membranes with narrow pore size distribution and high porosity. The method has the potential to be used with a broad range of tailor-made block copolymers to control functionality and selectivity for specific separations. However, the extension of this process to any new copolymer is challenging and time consuming, due to the complex interplay of influencing parameters, such as solvent composition, polymer molecular weights, casting solution concentration, and evaporation time. We propose here an effective method for designing new block copolymer membranes. The method consists of predetermining a trend line for the preparation of isoporous membranes, obtained by computing solvent properties, interactions and copolymer block sizes for a set of successful systems and using it as a guide to select the preparation conditions for new membranes. We applied the method to membranes based on poly(styrene-b-ethylene oxide) diblocks and extended it to newly synthesized poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) terpolymers. The trend line method can be generally applied to other new systems and is expected to dramatically shorten the path of isoporous membrane manufacture. The PS-b-P2VP-b-PEO membrane formation was investigated by in situ Grazing Incident Small Angle X-ray Scattering (GISAXS), which revealed a hexagonal micelle order with domain spacing clearly correlated to the membrane interpore distances.

  14. Metallo-supramolecular block copolymers : from synthesis to smart nanomaterials

    OpenAIRE

    Guillet, Pierre

    2008-01-01

    Supramolecular copolymers have become of increasing interest in recent years for the search of new materials with tunable properties. In particular, metallo-supramolecular block copolymers have seen important progresses since the last five years. In this thesis, a library of metallo-supramolecular amphiphilic block copolymers containing a hydrophilic block, linked to a hydrophobic block, through a metal-ligand complex has been investigated. The micelles formed in water from these copolymers...

  15. Regulating block copolymer phases via selective homopolymers

    International Nuclear Information System (INIS)

    The phase behavior of strongly segregated AB diblock copolymer and selective C homopolymer blends is examined theoretically using a combination of strong stretching theory (SST) and self-consistent field theory (SCFT). The C-homopolymer is immiscible with the B-blocks but strongly attractive with the A-blocks. The effect of homopolymer content on the order-order phase transitions is analyzed. It is observed that, for AB diblock copolymers with majority A-blocks, the addition of the C-homopolymers results in lamellar to cylindrical to spherical phase transitions because of the A/C complexation. For diblock copolymers with minor A-blocks, adding C-homopolymers leads to transitions from spherical or cylindrical morphology with A-rich core to lamellae to inverted cylindrical and spherical morphologies with B-rich core. The results from analytical SST and numerical SCFT are in good agreement within most regions of the phase diagram. But the deviation becomes more obvious when the composition of A-blocks is too small and the content of added C-homopolymers is large enough, where the SCFT predicts a narrow co-existence region between different ordered phases. Furthermore, it is found that the phase behavior of the system is insensitive to the molecular weight of C-homopolymer

  16. Fast assembly of ordered block copolymer nanostructures through microwave annealing.

    Science.gov (United States)

    Zhang, Xiaojiang; Harris, Kenneth D; Wu, Nathanael L Y; Murphy, Jeffrey N; Buriak, Jillian M

    2010-11-23

    Block copolymer self-assembly is an innovative technology capable of patterning technologically relevant substrates with nanoscale precision for a range of applications from integrated circuit fabrication to tissue interfacing, for example. In this article, we demonstrate a microwave-based method of rapidly inducing order in block copolymer structures. The technique involves the usage of a commercial microwave reactor to anneal block copolymer films in the presence of appropriate solvents, and we explore the effect of various parameters over the polymer assembly speed and defect density. The approach is applied to the commonly used poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) families of block copolymers, and it is found that the substrate resistivity, solvent environment, and anneal temperature all critically influence the self-assembly process. For selected systems, highly ordered patterns were achieved in less than 3 min. In addition, we establish the compatibility of the technique with directed assembly by graphoepitaxy. PMID:20964379

  17. Dynamics of Block Copolymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mochrie, Simon G. J.

    2014-09-09

    A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene– isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.

  18. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  19. Materials Design for Block Copolymer Lithography

    Science.gov (United States)

    Sweat, Daniel Patrick

    Block copolymers (BCPs) have attracted a great deal of scientific and technological interest due to their ability to spontaneously self-assemble into dense periodic nanostructures with a typical length scale of 5 to 50 nm. The use of self-assembled BCP thin-films as templates to form nanopatterns over large-area is referred to as BCP lithography. Directed self-assembly of BCPs is now viewed as a viable candidate for sub-20 nm lithography by the semiconductor industry. However, there are multiple aspects of assembly and materials design that need to be addressed in order for BCP lithography to be successful. These include substrate modification with polymer brushes or mats, tailoring of the block copolymer chemistry, understanding thin-film assembly and developing epitaxial like methods to control long range alignment. The rational design, synthesis and self-assembly of block copolymers with large interaction parameters (chi) is described in the first part of this dissertation. Two main blocks were chosen for introducing polarity into the BCP system, namely poly(4-hydroxystyrene) and poly(2-vinylpyridine). Each of these blocks are capable of ligating Lewis acids which can increase the etch contrast between the blocks allowing for facile pattern transfer to the underlying substrate. These BCPs were synthesized by living anionic polymerization and showed excellent control over molecular weight and dispersity, providing access to sub 5-nm domain sizes. Polymer brushes consist of a polymer chain with one end tethered to the surface and have wide applicability in tuning surface energy, forming responsive surfaces and increasing biocompatibility. In the second part of the dissertation, we present a universal method to grow dense polymer brushes on a wide range of substrates and combine this chemistry with BCP assembly to fabricate nanopatterned polymer brushes. This is the first demonstration of introducing additional functionality into a BCP directing layer and opens up

  20. From Block Copolymers to Nano-porous Materials

    DEFF Research Database (Denmark)

    Vigild, Martin Etchells; Ndoni, Sokol; Berg, Rolf Henrik

    2003-01-01

    Quantitative etching of the polydimethylsiloxane block in a series of polystyrene-polydimethylsiloxane (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride (HF) renders a nanoporous material with the remaining PS maintaining the original morphology...

  1. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    OpenAIRE

    Hoarfrost, Megan Lane

    2012-01-01

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the additio...

  2. Surface tension of micellar block copolymer films

    International Nuclear Information System (INIS)

    Surface tensions of micellar block copolymers of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) films are obtained by X-ray diffuse scattering. PS-b-PDMS films on Si substrates with the thicknesses from 36 to 588 nm were investigated at temperatures of 30 - 215 .deg. C. The surface tension reflects the concentration of PDMS micelles which are preferably located at the surface. The molar fraction of PDMS micelles near the surface is estimated by using angle-resolved X-ray photoelectron spectroscopy.

  3. Oriented Protein Nanoarrays on Block Copolymer Template.

    Science.gov (United States)

    Shen, Lei; Zhu, Jintao

    2016-03-01

    Here, a simple yet robust method is developed to fabricate oriented protein nanoarrays by employing a block copolymer (BCP) template, which presents nano-scaled spot areas at high-density arrays. Unlike the conventional BCP nanolithography, the BCP platform described here resists nonspecific protein adsorption and prevents the denaturation of immobilized proteins in aqueous solution. The orderly arranged array areas are functionalized by linking chemistry which allows for the precise control of protein orientation. This approach allows us to generate potentially oriented protein nanoarrays at high-density array spots, which is useful for miniaturized nanoarrays within high-throughput proteomic applications. PMID:26785818

  4. Nanostructured Polysulfone-Based Block Copolymer Membranes

    KAUST Repository

    Xie, Yihui

    2016-05-01

    The aim of this work is to fabricate nanostructured membranes from polysulfone-based block copolymers through self-assembly and non-solvent induced phase separation. Block copolymers containing polysulfone are novel materials for this purpose providing better mechanical and thermal stability to membranes than polystyrene-based copolymers, which have been exclusively used now. Firstly, we synthesized a triblock copolymer, poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) through polycondensation and reversible addition-fragmentation chain-transfer polymerization. The obtained membrane has a highly porous interconnected skin layer composed of elongated micelles with a flower-like arrangement, on top of the graded finger-like macrovoids. Membrane surface hydrolysis was carried out in a combination with metal complexation to obtain metal-chelated membranes. The copper-containing membrane showed improved antibacterial capability. Secondly, a poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) triblock copolymer obtained by hydrolyzing poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) formed a thin film with cylindrical poly(acrylic acid) microdomains in polysulfone matrix through thermal annealing. A phase inversion membrane was prepared from the same polymer via self-assembly and chelation-assisted non-solvent induced phase separation. The spherical micelles pre-formed in a selective solvent mixture packed into an ordered lattice in aid of metal-poly(acrylic acid) complexation. The space between micelles was filled with poly(acrylic acid)-metal complexes acting as potential water channels. The silver0 nanoparticle-decorated membrane was obtained by surface reduction, having three distinct layers with different particle sizes. Other amphiphilic copolymers containing polysulfone and water-soluble segments such as poly(ethylene glycol) and poly(N-isopropylacrylamide) were also synthesized through coupling reaction and copper0-mediated

  5. Synthesis and Morphological Characterization of Block Copolymers for Improved Biomaterials

    OpenAIRE

    Schricker, Scott; Palacio, Manuel; Thirumamagal, B.T.S.; Bhushan, Bharat

    2010-01-01

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxy...

  6. Influence of 1,2-PB matrix cross-linking on structure and properties of selectively etched 1,2-PB-b-PDMS block copolymers

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Andreasen, Jens Wenzel; Vigild, Martin Etchells;

    2007-01-01

    cross-linked samples in toluene was converted into a degree of cross-linking following the Flory scheme; a simple relation between the Flory cross-linking degree and the fraction of consumed double bonds during the cross-linking reaction followed. The structure of the block copolymer at different stages...

  7. Interface-enforced complexation between copolymer blocks.

    Science.gov (United States)

    Steinschulte, Alexander A; Xu, Weinan; Draber, Fabian; Hebbeker, Pascal; Jung, Andre; Bogdanovski, Dimitri; Schneider, Stefanie; Tsukruk, Vladimir V; Plamper, Felix A

    2015-05-14

    Binary diblock copolymers and corresponding ternary miktoarm stars are studied at oil-water interfaces. All polymers contain oil-soluble poly(propylene oxide) PPO, water-soluble poly(dimethylaminoethyl methacrylate) PDMAEMA and/or poly(ethylene oxide) PEO. The features of their Langmuir compression isotherms are well related to the ones of the corresponding homopolymers. Within the Langmuir-trough, PEO-b-PPO acts as the most effective amphiphile compared to the other PPO-containing copolymers. In contrast, the compression isotherms show a complexation of PPO and PDMAEMA for PPO-b-PDMAEMA and the star, reducing their overall amphiphilicity. Such complex formation between the blocks of PPO-b-PDMAEMA is prevented in bulk water but facilitated at the interface. The weakly-interacting blocks of PPO-b-PDMAEMA form a complex due to their enhanced proximity in such confined environments. Scanning force microscopy and Monte Carlo simulations with varying confinement support our results, which are regarded as compliant with the mathematical random walk theorem by Pólya. Finally, the results are expected to be of relevance for e.g. emulsion formulation and macromolecular engineering. PMID:25807174

  8. Controlling Structure in Sulfonated Block Copolymer Membranes

    Science.gov (United States)

    Truong, Phuc; Stein, Gila; Strzalka, Joe

    2015-03-01

    In many ionic block copolymer systems, the strong incompatibility between ionic and non-ionic segments will trap non-equilibrium structures in the film, making it difficult to engineer the optimal domain sizes and transport pathways. The goal of this work is to establish a framework for controlling the solid-state structure of sulfonated pentablock copolymer membranes. They have ABCBA block sequence, where A is poly(t-butyl styrene), B is poly(hydrogenated isoprene), and C is poly(styrene sulfonate). To process into films, the polymer is dissolved in toluene/n-propanol solvent mixtures, where the solvent proportions and the polymer loading were both varied. Solution-state structure was measured with small angle X-ray scattering (SAXS). We detected micelles with radii that depend on the solvent composition and polymer loading. Film structure was measured with grazing-incidence SAXS, which shows (i) domain periodicity is constant throughout film thickness; (ii) domain periodicity depends on solvent composition and polymer loading, and approximately matches the micelle radii in solutions. The solid-state packing is consistent with a hard sphere structure factor. Results suggest that solid-state structure can be tuned by manipulating the solution-state self-assembly.

  9. Self-assembled materials from thermosensitive and biohybrid block copolymers

    NARCIS (Netherlands)

    de Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purpose

  10. Synthesis and Characterization of Novel Magnetite Nanoparticle Block Copolymer Complexes

    OpenAIRE

    Zhang, Qian

    2007-01-01

    Superparamagnetic Magnetite (Fe3O4) nanoparticles were synthesized and complexed with carboxylate-functionalized block copolymers, and aqueous dispersions of the complexes were investigated as functions of their chemical and morphological structures. The block copolymer dispersants possessed either poly(ethylene oxide), poly(ethylene oxide-co-propylene oxide), or poly(ethylene oxide-b-propylene oxide) outer blocks, and all contained a polyurethane center block with pendant carboxylate functi...

  11. Anomalous Micellization of Pluronic Block Copolymers

    Science.gov (United States)

    Leonardi, Amanda; Ryu, Chang Y.

    2014-03-01

    Poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, commercially known as Pluronics, are a unique family of amphiphilic triblock polymers, which self-assemble into micelles in aqueous solution. These copolymers have shown promise in therapeutic, biomedical, cosmetic, and nanotech applications. As-received samples of Pluronics contain low molecular weight impurities (introduced during the manufacturing and processing), that are ignored in most applications. It has been observed, however, that in semi-dilute aqueous solutions, at concentrations above 1 wt%, the temperature dependent micellization behavior of the Pluronics is altered. Anomalous behavior includes a shift of the critical micellization temperature and formation of large aggregates at intermediate temperatures before stable sized micelles form. We attribute this behavior to the low molecular weight impurities that are inherent to the Pluronics which interfere with the micellization process. Through the use of Dynamic Light Scattering and HPLC, we compared the anomalous behavior of different Pluronics of different impurity levels to their purified counterparts.

  12. Block copolymer ion gels for gas separation

    Science.gov (United States)

    Gu, Yuanyan; Lodge, Timothy

    2012-02-01

    Carbon dioxide removal from light gases (eg. N2, CH4, and H2) is a very important technology for industrial applications such as natural gas sweetening, CO2 capture from coal-fire power plant exhausts and hydrogen production. Current CO2 separation method uses amine-absorption, which is energy-intensive and requires frequent maintenance. Membrane separation is a cost-effective solution to this problem, especially in small-scale applications. Ionic liquids have recently received increasing interest in this area because of their selective solubility for CO2 and non-volatility. However, ionic liquid itself lacks the persistent structure and mechanical integrity to withstand the high pressure for gas separation. Here, we report the development and gas separation performances of physically crosslinked ion gels based on self-assembly of ABA-triblock copolymers in ionic liquids. Three different types of polymers was used to achieve gelation in ionic liquids. Specifically, a triblock copolymer ion gel with a polymerized ionic liquid mid-block shows performances higher than the upper bound of well-known ``Robeson Plot'' for CO2/N2.

  13. Synthesis and morphological characterization of block copolymers for improved biomaterials

    International Nuclear Information System (INIS)

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxyethyl methacrylate. The block copolymers were synthesized using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Since the surface morphology is critical for successful cell growth, atomic force microscopy (AFM) studies were conducted for selected block copolymers. The topography, phase angle and friction maps were obtained in dry and physiological buffer environments to study the morphology. Results of AFM imaging identified the presence of polymer domains corresponding to the copolymer components. The distribution of nanoscale features in these block copolymers is comparable to those found on other surfaces that exhibit favorable cell adhesion and growth. In physiological buffer medium, the hydrophilic component of the block copolymer (acrylic acid or hydroxyethyl methacrylate) appears to be present in greater amounts on the surface as a consequence of water absorption and swelling.

  14. Synthesis and morphological characterization of block copolymers for improved biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Schricker, Scott, E-mail: Schricker.1@osu.edu [Restorative and Prosthetic Dentistry Section, College of Dentistry, The Ohio State University, Columbus, OH 43210 (United States); Palacio, Manuel [Nanoprobe Laboratory for Bio- and Nanotechnology and Biomimetics, The Ohio State University, Columbus, OH 43210 (United States); Thirumamagal, B.T.S. [Restorative and Prosthetic Dentistry Section, College of Dentistry, The Ohio State University, Columbus, OH 43210 (United States); Bhushan, Bharat [Nanoprobe Laboratory for Bio- and Nanotechnology and Biomimetics, The Ohio State University, Columbus, OH 43210 (United States)

    2010-05-15

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxyethyl methacrylate. The block copolymers were synthesized using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Since the surface morphology is critical for successful cell growth, atomic force microscopy (AFM) studies were conducted for selected block copolymers. The topography, phase angle and friction maps were obtained in dry and physiological buffer environments to study the morphology. Results of AFM imaging identified the presence of polymer domains corresponding to the copolymer components. The distribution of nanoscale features in these block copolymers is comparable to those found on other surfaces that exhibit favorable cell adhesion and growth. In physiological buffer medium, the hydrophilic component of the block copolymer (acrylic acid or hydroxyethyl methacrylate) appears to be present in greater amounts on the surface as a consequence of water absorption and swelling.

  15. Block Copolymer Metastability: Scientific Nightmare or Engineering Dream?

    Science.gov (United States)

    Bates, Frank S.

    1997-03-01

    Most experimental studies and almost all theories that deal with block copolymers, or mixtures of block copolymers and homopolymers, have been designed from an equilibrium perspective. Yet a myriad of factors conspire to retard approach to equilibrium in these systems, including: subtle features in the free energy surface that are controlled by ordered state symmetry; a coupling between microphase separation and entanglement dynamics; complex molecular architectures such as multiblock, starblock, and miktoarm. Even unentangled low molecular weight diblock copolymers, the simplest and dynamically least encumbered materials, exhibit long-lived metastable states that confound attempts to validate equilibrium theories. However, this apparent dilemma can be exploited through clever processing strategies. This lecture will address two opposing consequences of block copolymer metastability. The first is a potential nightmare: Can we ever establish universal block copolymer phase diagrams? The second is the stuff of dreams: Self-assembled thermoset nanocomposites.

  16. STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATION OF TIRE TREAD

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; CHEN Weijie; MU Ruifeng; WANG Yongwei; YU Fengnian; LIU Qing

    1996-01-01

    This paper mainly deals with the design and synthesis of a novel styrene-butadiene block copolymer. When this copolymer is used in the tread portion of tyres, it can improve wet skid resistance and reduce rolling resistance without sacrificing its general physicalmechanical properties. The visco-elastic curve of tire tread using the novel copolymer as its rubber portion was showed. Reactivity ratios for two monomers in the polymerizing system were calculated. The diagrams of differential, integral and finite difference calculi throughout the whole molecular chain were presented. The influence of the micro- and macro-structure of the copolymer chain on wet skid resistance and rolling resistance was discussed.

  17. Influence of substrate interaction and confinement on electric-field-induced transition in symmetric block-copolymer thin films

    Science.gov (United States)

    Mukherjee, Arnab; Mukherjee, Rajdip; Ankit, Kumar; Bhattacharya, Avisor; Nestler, Britta

    2016-03-01

    In the present work, we study morphologies arising due to competing substrate interaction, electric field, and confinement effects on a symmetric diblock copolymer. We employ a coarse-grained nonlocal Cahn-Hilliard phenomenological model taking into account the appropriate contributions of substrate interaction and electrostatic field. The proposed model couples the Ohta-Kawasaki functional with Maxwell equation of electrostatics, thus alleviating the need for any approximate solution used in previous studies. We calculate the phase diagram in electric-field-substrate strength space for different film thicknesses. In addition to identifying the presence of parallel, perpendicular, and mixed lamellae phases similar to analytical calculations, we also find a region in the phase diagram where hybrid morphologies (combination of two phases) coexist. These hybrid morphologies arise either solely due to substrate affinity and confinement or are induced due to the applied electric field. The dependence of the critical fields for transition between the various phases on substrate strength, film thickness, and dielectric contrast is discussed. Some preliminary 3D results are also presented to corroborate the presence of hybrid morphologies.

  18. Morphological studies on block copolymer modified PA 6 blends

    Energy Technology Data Exchange (ETDEWEB)

    Poindl, M., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de [Institut für Kunststofftechnik, University of Stuttgart (Germany)

    2014-05-15

    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  19. Molecular Transfer Printing Using Block Copolymers

    Science.gov (United States)

    Ji, Shengxiang; Liu, Chi-Chun; Liu, Guoliang; Nealey, Paul

    2009-03-01

    We report a new parallel patterning technique, molecular transfer printing (MTP), for replicating geometrically complex patterns over macroscopic areas with sub-15 nm feature dimensions, and the ability to replicate the same pattern multiple times. In MTP, inks are mixed with block copolymers (BCPs) and deposited as films on a substrate. The inks are compatible with only one block of the BCP, and sequestered into domains of nanometer scale dimensions after microphase separation. A second substrate is then placed in contact with the surface of the film. By designing the inks to react, adsorb, or otherwise interact with the second substrate, inks are transferred to the second substrate in the exact pattern of domains present at the surface of the ``master'' BCP film. Here we demonstrate high degrees of perfection on both line and dot patterns. We also show that 1) the master template can be regenerated, 2) the resultant replica can be used to direct the assembly of BCPs and as a daughter master for MTP, and 3) the master and daughter templates can be reused tens of times.

  20. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes

    OpenAIRE

    Schultz, Alison

    2013-01-01

           Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations be...

  1. Radiation crosslinked block copolymer blends with improved impact resistance

    International Nuclear Information System (INIS)

    Polymer blends having high impact resistance after mechanical working are produced by blending together a non-elastomeric monovinylidene aromatic polymer such as polystyrene with an elastomeric copolymer, such as a block copolymer of styrene and butadiene, in the form of crosslinked, colloidal size particles

  2. Stereo block copolymers of L- and D-lactides

    NARCIS (Netherlands)

    Yui, Nobuhiko; Dijkstra, Pieter J.; Feijen, Jan

    1990-01-01

    Sequential diblock copolymers composed of L- and D-lactic acid residues were synthesized through a living ring-opening polymerization of L- and D-lactide initiated by aluminium tris(2-propanolate). The composition of the block copolymers was varied by changing the reaction conditions and monomer ove

  3. Mechanical Properties of Weakly Segregated Block Copolymers. 3. Influence of Strain Rate and Temperature on Tensile Properties of Poly(styrene-b-butyl methacrylate) Diblock Copolymers with Different Morphologies

    NARCIS (Netherlands)

    Weidisch, R.; Stamm, M.; Michler, G.H.; Fischer, H.R.; Jérôme, R.

    1999-01-01

    Poly(styrene-b-butyl methacrylate) diblock copolymers, PS-6-PBMA, with different morphologies are investigated with respect to the influence of strain rate and temperature on tensile properties. In the first part the mechanical properties of bicontinuous and perforated lamellar structure are compare

  4. Synthesis of Amylose-b-P2 VP Block Copolymers.

    Science.gov (United States)

    Kumar, Kamlesh; Woortman, Albert J J; Loos, Katja

    2015-12-01

    A new class of rod-coil block copolymers is synthesized by chemoenzymatic polymerization. In the first step, maltoheptaose, which acts as a primer for the synthesis of amylose, is attached to poly(2-vinyl pyridine) (P2 VP). The enzymatic polymerization of maltoheptaose is carried out by phosphorylase to obtain amylose-b-P2 VP block copolymers. The block copolymer is characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and wide-angle X-ray scattering techniques. The designed molecules combine the inclusion complexation ability of amylose with the supramolecular complexation ability of P2 VP and therefore this kind of rod-coil block copolymers can be used to generate well-organized novel self-assembled structures. PMID:26437256

  5. Nanopatterned articles produced using surface-reconstructed block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

    2016-06-07

    Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

  6. Ionic Block Copolymers for Anion Exchange Membranes

    Science.gov (United States)

    Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan

    2013-03-01

    Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy. US Army MURI (W911NF1010520)

  7. Adsorption of semiflexible block copolymers on homogeneous surfaces

    OpenAIRE

    Cerdà, Joan J.; Sintes, Tomàs; Sumithra, K.

    2005-01-01

    We present the results of extensive numerical off-lattice Monte Carlo simulations of semiflexible block-copolymer chains adsorbed onto flat homogeneous surfaces. We have compared the behavior of several chain structures, such as homopolymers, diblocks, (AαBα) block copolymers, and random heteropolymers. In all the cases studied, we have found the adsorption process to be favored with an increase of the chain rigidity. Particularly, the adsorption of diblock structures becomes a two-step proce...

  8. Aggregation behavior of water-soluble amphiphilic block copolymers

    OpenAIRE

    Bonné, Tune Bjarke

    2007-01-01

    Polymers and block copolymers based on 2-alkyl-2-oxazoline have the advantage that their hydrophobicity can be varied by changing the length of the alkyl side chain and that fluorescence groups can be attached to the block ends. We have studied the aggregation behavior of 2-alkyl-2-oxazoline based diblock, triblock and random copolymers in aqueous solutions, using fluorescence correlation spectroscopy (FCS), where fluorescence labeled polymers were used as tracers. FCS experiments in combinat...

  9. Self-assembled materials from thermosensitive and biohybrid block copolymers

    OpenAIRE

    De Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purposes. Some of the synthesized polymers were biohybrid, in the sense that they contained peptide segments which enabled their cleavage by enzymes that are upregulated in diseased tissues. First, method...

  10. New adhesive systems based on functionalized block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kent, M.; Saunders, R.; Hurst, M.; Small, J.; Emerson, J.; Zamora, D.

    1997-05-01

    The goal of this work was to evaluate chemically-functionalized block copolymers as adhesion promoters for metal/thermoset resin interfaces. Novel block copolymers were synthesized which contain pendant functional groups reactive toward copper and epoxy resins. In particular, imidazole and triazole functionalities that chelate with copper were incorporated onto one block, while secondary amines were incorporated onto the second block. These copolymers were found to self-assemble from solution onto copper surfaces to form monolayers. The structure of the adsorbed monolayers were studied in detail by neutron reflection and time-of-flight secondary ion mass spectrometry. The monolayer structure was found to vary markedly with the solution conditions and adsorption protocol. Appropriate conditions were found for which the two blocks form separate layers on the surface with the amine functionalized block exposed at the air surface. Adhesion testing of block copolymer-coated copper with epoxy resins was performed in both lap shear and peel modes. Modest enhancements in bond strengths were observed with the block copolymer applied to the native oxide. However, it was discovered that the native oxide is the weak link, and that by simply removing the native oxide, and then applying an epoxy resin before the native oxide can reform, excellent bond strength in the as-prepared state as well as excellent retention of bond strength after exposure to solder in ambient conditions are obtained. It is recommended that long term aging studies be performed with and without the block copolymer. In addition, the functionalized block copolymer method should be evaluated for another system that has inherently poor bonding, such as the nickel/silicone interface, and for systems involving metals and alloys which form oxides very rapidly, such as aluminum and stainless steel, where bonding strategies involve stabilizing the native oxide.

  11. New routes to the synthesis of amylose-block-polystyrene rod-coil block copolymers

    NARCIS (Netherlands)

    Loos, Katja; Müller, Axel H.E.

    2002-01-01

    Hybrid block copolymers amylose-block-polystyrene were synthesized by covalent attachment of maltoheptaose derivatives to end-functionalized polystyrene and subsequent enzymatic grafting from polymerization. The maltoheptaose derivatives were attached by reductive amination or hydrosilation to amino

  12. Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films

    Energy Technology Data Exchange (ETDEWEB)

    Arges, Christopher G.; Kambe, Yu; Suh, Hyo Seon; Ocola, Leonidas E.; Nealey, Paul F.

    2016-03-08

    Connecting structure and morphology to bulk transport properties, such as ionic conductivity, in nanostructured polymer electrolyte materials is a difficult proposition because of the challenge to precisely and accurately control order and the orientation of the ionic domains in such polymeric films. In this work, poly(styrene-block-2-vinylpyridine) (PSbP2VP) block copolymers were assembled perpendicularly to a substrate surface over large areas through chemical surface modification at the substrate and utilizing a versatile solvent vapor annealing (SVA) technique. After block copolymer assembly, a novel chemical vapor infiltration reaction (CVIR) technique selectively converted the 2-vinylpyridine block to 2-vinyl n-methylpyridinium (NMP+ X-) groups, which are anion charge carriers. The prepared block copolymer electrolytes maintained their orientation and ordered nanostructure upon the selective introduction of ion moieties into the P2VP block and post ion-exchange to other counterion forms (X- = chloride, hydroxide, etc.). The prepared block copolymer electrolyte films demonstrated high chloride ion conductivities, 45 mS cm(-1) at 20 degrees C in deionized water, the highest chloride ion conductivity for anion conducting polymer electrolyte films. Additionally, straight-line lamellae of block copolymer electrolytes were realized using chemoepitaxy and density multiplication. The devised scheme allowed for precise and accurate control of orientation of ionic domains in nanostructured polymer electrolyte films and enables a platform for future studies that examines the relationship between polymer electrolyte structure and ion transport.

  13. Block Copolymers of Ethylene Oxide and Styrene Oxide.New Copolymer Surfactants(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Zhuo Yang; David Attwood; Colin Booth

    2003-01-01

    @@ 3.2. Association Number Figure 5 shows the dependence of the weight-average association number (Nw,measured by static light scattering, solution temperature 30 °C) on hydrophobe block length for ES and ESEblock copolymers.

  14. Solubility and self-assembly of amphiphilic gradient and block copolymers in supercritical CO2

    International Nuclear Information System (INIS)

    This work aims at demonstrating the interest of gradient copolymers in supercritical CO2 in comparison with block copolymers. Gradient copolymers exhibit a better solubility in supercritical CO2 than block copolymers, as attested by cloud point data. The self-assembly of gradient and block copolymers in dense CO2 has been characterized by Small-Angle Neutron Scattering (SANS); and it is shown that it is not fundamentally modified when changing from block copolymers to gradient copolymers. Therefore, gradient copolymers are advantageous thanks to their easier synthesis and their solubility at lower pressure while maintaining a good ability for self-organization in dense CO2. (authors)

  15. Poly(lactide)-block-poly([epsilon]-caprolactone-co-[epsilon]-decalactone)-block-poly(lactide) copolymer elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Schneiderman, Deborah K.; Hill, Erin M.; Martello, Mark T.; Hillmyer, Marc A. (UMM)

    2015-08-28

    Batch ring opening transesterification copolymerization of ε-caprolactone and ε-decalactone was used to generate statistical copolymers over a wide range of compositions and molar masses. Reactivity ratios determined for this monomer pair, rCL = 5.9 and rDL = 0.03, reveal ε-caprolactone is added preferentially regardless of the propagating chain end. Relative to poly(ε-caprolactone) the crystallinity and melting point of these statistical copolymers were depressed by the addition of ε-decalactone; copolymers containing greater than 31 mol% (46 wt%) ε-decalactone were amorphous. Poly(lactide)-block-poly(ε-caprolactone-co-ε-decalactone)-block-poly(lactide) triblock polymers were also prepared and used to explore the influence of midblock composition on the temperature dependent Flory-Huggins interaction parameter (χ). In addition, uniaxial extension tests were used to determine the effects of midblock composition, poly(lactide) content, and molar mass on the mechanical properties of these new elastomeric triblocks.

  16. Ion and temperature sensitive polypeptide block copolymer.

    Science.gov (United States)

    Joo, Jae Hee; Ko, Du Young; Moon, Hyo Jung; Shinde, Usha Pramod; Park, Min Hee; Jeong, Byeongmoon

    2014-10-13

    A poly(ethylene glycol)/poly(L-alanine) multiblock copolymer incorporating ethylene diamine tetraacetic acid ([PA-PEG-PA-EDTA(m)) was synthesized as an ion/temperature dual stimuli-sensitive polymer, where the effect of different metal ions (Cu(2+), Zn(2+), and Ca(2+)) on the thermogelation of the polymer aqueous solution was investigated. The dissociation constants between the metal ions and the multiblock copolymer were calculated to be 1.2 × 10(-7), 6.6 × 10(-6), and 1.2 × 10(-4) M for Cu(2+), Zn(2+), and Ca(2+), respectively, implying that the binding affinity of the multiblock copolymer for Cu(2+) is much greater than that for Zn(2+) or Ca(2+). Atomic force microscopy and dynamic light scattering of the multiblock copolymer containing metal ions suggested micelle formation at low temperature, which aggregated as the temperature increased. Circular dichroism spectra suggested that changes in the α-helical secondary structure of the multiblock copolymer were more pronounced by adding Cu(2+) than other metal ions. The thermogelation of the multiblock copolymer aqueous solution containing Cu(2+) was observed at a lower temperature, and the modulus of the gel was significantly higher than that of the system containing Ca(2+) or Zn(2+), in spite of the same concentration of the metal ions and their same ionic valence of +2. The above results suggested that strong ionic complexes between Cu(2+) and the multiblock copolymer not only affected the secondary structure of the polymer but also facilitated the thermogelation of the polymer aqueous solution through effective salt-bridge formation even in a millimolar range of the metal ion concentration. Therefore, binding affinity of metal ions for polymers should be considered first in designing an effective ion/temperature dual stimuli-sensitive polymer. PMID:25178662

  17. Highly conductive side chain block copolymer anion exchange membranes.

    Science.gov (United States)

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days. PMID:27216558

  18. Aligned nanowires and nanodots by directed block copolymer assembly

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-29

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

  19. Aligned nanowires and nanodots by directed block copolymer assembly

    International Nuclear Information System (INIS)

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

  20. Method of forming oriented block copolymer line patterns, block copolymer line patterns formed thereby, and their use to form patterned articles

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Hong, Sung Woo; Lee, Doug Hyun; Park, Soojin; Xu, Ting

    2015-10-13

    A block copolymer film having a line pattern with a high degree of long-range order is formed by a method that includes forming a block copolymer film on a substrate surface with parallel facets, and annealing the block copolymer film to form an annealed block copolymer film having linear microdomains parallel to the substrate surface and orthogonal to the parallel facets of the substrate. The line-patterned block copolymer films are useful for the fabrication of magnetic storage media, polarizing devices, and arrays of nanowires.

  1. Observed frustration in confined block copolymers

    International Nuclear Information System (INIS)

    Symmetric diblock copolymers confined between two solid surfaces were studied by neutron reflectivity. A multilayered morphology with an integral number of layers oriented parallel to the solid interfaces was found in all cases. The period of the confined multilayers deviated from the bulk period in a cyclic manner as a function of the confined film thickness. A first-order transition occurred between the expanded and contracted states of the copolymer chains. The data suggest that the deviation of the period from the bulk value decreases with increasing separation distance

  2. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland

    2014-12-01

    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene and the selective layer with isopores was formed by micelle assembly of polystyrene-. b-poly-4-vinyl pyridine. The dual layers had an excellent interfacial adhesion and pore interconnectivity. The dual membranes showed pH response behavior like single layer block copolymer membranes with a low flux for pH values less than 3, a fast increase between pH4 and pH6 and a constant high flux level for pH values above 7. The dry/wet spinning process was optimized to produce dual layer hollow fiber membranes with polystyrene internal support layer and a shell block copolymer selective layer.

  3. Characterization of Lithium Polysulfide Salts in Homopolymers and Block Copolymers

    Science.gov (United States)

    Wang, Dunyang; Wujcik, Kevin; Balsara, Nitash

    Ion-conducting polymers are important for solid-state batteries due to the promise of better safety and the potential to produce higher energy density batteries. Nanostructured block copolymer electrolytes can provide high ionic conductivity and mechanical strength through microphase separation. One of the potential use of block copolymer electrolytes is in lithium-sulfur batteries, a system that has high theoretical energy density wherein the reduction of sulfur leads to the formation of lithium polysulfide intermediates. In this study we investigate the effect of block copolymer morphology on the speciation and transport properties of the polysulfides. The morphology and conductivities of polystyrene-b-poly(ethylene oxide) (SEO) containing lithium polysulfides were studies using small-angle X-ray scattering and ac impedance spectroscopy. UV-vis spectroscopy is being used to determine nature of the polysulfide species in poly(ethylene oxide) and SEO. Department of Energy, Soft Matter Electron Microscopy Program and Battery Materials Research Program.

  4. SANS and SAXS study of block copolymer/homopolymer mixtures

    International Nuclear Information System (INIS)

    The lateral and vertical components of the radius of gyration for a single block copolymer chain and those of a single homopolymer chain in the lamellar microdomain space formed by a mixture of diblock copolymers and homopolymers were investigated by means of small-angle neutron scattering (SANS) and the microdomain structures by small-angle X-ray scattering (SAXS). The homopolymers whose molecular weights are much smaller than that of the corresponding chains of the block copolymers were used so that the homopolymers were uniformly solubilized in the corresponding microdomains. The SANS result suggests that the homopolymer chains in the microdomain space as well as the block copolymer chains are more compressed in the direction parallel to the interface and more stretched in the direction perpendicular to the interface than the corresponding unperturbed polymer chains with the same molecular weight. On increasing the volume fraction of the homopolymers the thickness of the lamellar microdomains increases. The block copolymer chains were found to undergo an isochoric affine deformation on addition of the homopolymers or with the change of the thickness of the lamellar microdomains. (orig.)

  5. Controlling block copolymer phase behavior using ionic surfactant

    Science.gov (United States)

    Ray, D.; Aswal, V. K.

    2016-05-01

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO26PO39EO26)] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle-surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  6. Interfacial Phenomena of Solvent-diluted Block Copolymers

    OpenAIRE

    Cohen, Shai; Andelman, David

    2013-01-01

    A phenomenological mean-field theory is used to investigate the properties of solvent-diluted di-block copolymers (BCP), in which the two BCP components (A and B) form a variety of phases that are diluted by a solvent (S). Using this approach, we model mixtures of di-block copolymers and a solvent and obtained the corresponding critical behavior. In the low solvent limit, we find how the critical point depends on the solvent density. Due to the non-linear nature of the coupling between the A/...

  7. Block and Graft Copolymers of Polyhydroxyalkanoates

    Science.gov (United States)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  8. Chain exchange kinetics of block copolymer micelles in ionic liquids

    Science.gov (United States)

    Ma, Yuanchi; Lodge, Timothy

    The chain exchange kinetics of block copolymer micelles has been studied using time-resolved small-angle neutron scattering (TR-SANS), a key tool in determining the average micelle composition in contrast-matched solvents. In this work, PMMA-block-PnBMA was selected as the model block copolymer, which has a LCST behavior in the common ionic liquids, [EMIM][TFSI] and [BMIM][TFSI]. We examined the chain exchange kinetics of three PMMA-block-PnBMA copolymers, with identical PMMA block length (MPMMA = 25000) and different PnBMA block lengths (MPnBMA = 24000, 35000 and 53000); the Flory-Huggins interaction parameter (χ) between the core (PnBMA) and the solvent were varied by mixing [EMIM][TFSI] and [BMIM][TFSI] in different ratios. We found that the relaxation of the initial segregation of h- and d- micelles followed the same form with the time as previously developed by our group. Assuming that single chain expulsion is the rate limiting step, the thermal barrier was found to depend linearly on the core block length (Ncore) . Furthermore, the effect of χ on the chain exchange kinetics will also be discussed.

  9. Dissipative Particle Dynamics Simulation of Onion Phase in Star-block Copolymer

    Institute of Scientific and Technical Information of China (English)

    WU Shao-gui; DU Ting-ting

    2013-01-01

    A dissipative particle dynamics simulation technique was used to investigate the effect of molecular architecture of star-block copolymer on the patterned structure in a nanodroplet.With increasing the ratio of solvophilic to block length to solvophobic block length(RH/T),solvophobic sphere,ordered hexagonal phase,onion phase,perforated onion phase and flocculent phase are formed,respectively.Since onion phase has potential application in controlled drug release,it has received wide attention experimentally and theoretically.Our simulation indicates onion phase forms at a certain RH/T(close to but less than 1).A star-block copolymer molecule has two conformations in onion phase:either fully located in a shell or shared by two neighboring shells.Central structure affects onion's final shape.The molecular number of the copolymer in each shell is a quadratic function of the shell's radius.The arm number of star-block copolymer has little influence on onion's structure,but slightly affects the solvent content.Additionally,we studied the influence of arm length on onion's structure.

  10. Segmented block copolymers with polyesteramide blocks of uniform length: synthesis

    NARCIS (Netherlands)

    Gaymans, R.J.; Haan, de J.L.

    1993-01-01

    Segmented copolymers were synthesized from poly(tetramethylene oxide) with hydroxy end-groups or aliphatic diols and a short-chain diester diamide with a uniform length. The diester diamide (N,N'-bis(p-carbomethoxybenzoyl)butanediamine) (Tm = 257°C) used is made from butanediamine and an excess of d

  11. Stability of ordered phases in block copolymer melts and solutions

    Indian Academy of Sciences (India)

    Kell Mortensen

    2008-11-01

    Block copolymer melts and solutions assemble into nanosized objects that order into a variety of phases, depending on molecular parameters and mutual interactions. Beyond the classical phases of lamella ordered sheets, hexagonally ordered cylinders and cubic ordered spheres, the complex bicontinuous gyroid phase and the modulated lamellar phase are observed near the phase boundaries. The stability of these phases has been discussed on the basis of theoretical calculations. Here, we will discuss new experimental results showing that the given ordered phase depends critically on both molecular purity and mechanical treatment of the sample. While a variety of block copolymer micellar systems have been shown to undergo the liquid-to-bcc-to-fcc phase sequence upon varying micellar parameters (or temperature), we find for a purified system a different sequence, namely liquid-to-fcc-to-bcc [1]. The latter sequence is by the way the one predicted for pure block copolymer melts. External fields like shear or stress may also affect the ordered phase. Applying well-controlled large-amplitude oscillatory shear can be used to effectively control the texture of soft materials in the ordered states. As an example, we present results on a body-centred-cubic phase of a block copolymer system, showing how a given texture can be controlled with the application of specific shear rate and shear amplitude [2,3]. Shear may however also affect the thermodynamic ground state, causing shear-induced ordering and disordering (melting), and shear-induced order–order transitions. We will present data showing that the gyroid state of diblock copolymer melts is unstable when exposed to large amplitude/frequency shear, transforming into the hexagonal cylinder phase [4]. The transformation is completely reversible. With the rather slow kinetics in the transformation of copolymer systems, it is possible in detail to follow the complex transformation process, where we find transient ordered

  12. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren

    2005-01-01

    Polystyrene-b-alkyl, polystyrene-b-polybutadiene-b-polystyrene, and polystyrene-b-poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg/mol and...... minimum polystyrene content of 50 w/w%, which by us is predicted as the limits for solubility of polystyrene-b-alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight...... of approximately 1 kg/mol and an alkyl block with a molecular weight of approximately of 0.3 kg/mol. The efficiency of the block copolymers as plasticizers increases with decreasing molecular weight and polystyrene content. In addition, polystyrene-b-alkyl is found to be an efficient plasticizer also...

  13. Complexes of block copolymers in solution: tree approximation

    NARCIS (Netherlands)

    Geurts, Bernard J.; Damme, van Ruud

    1989-01-01

    We determine the statistical properties of block copolymer complexes in solution. These complexes are assumed to have the topological structure of (i) a tree or of (ii) a line-dressed tree. In case the structure is that of a tree, the system is shown to undergo a gelation transition at sufficiently

  14. Asymmetric block copolymers confined in a thin film

    NARCIS (Netherlands)

    Huinink, HP; Brokken-Zijp, JCM; van Dijk, MA; Sevink, GJA

    2000-01-01

    We have used a dynamic density functional theory (DDFT) for polymeric systems, to simulate the formation of micro phases in a melt of an asymmetric block copolymer, A(n)B(m)(f(A) = 1/3), both in the bulk and in a thin film. In the DDFT model a polymer is represented as a chain of springs and beads.

  15. SANS study of nanoparticles based on block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Pospíšil, Herman; Kuklin, A. I.

    Dubna: Joint Institute for Nuclear Research, Lomonosov Moscow State University, 2005. s. 22. ISBN 5-9530-0086-3. [Workshop on Investigations at the IBR-2 Pulsed Reactor /4./. 15.6.2005-18.6.2005, Dubna] R&D Projects: GA ČR GA203/03/0600 Keywords : SANS * block copolymer micelles * nanoparticles Subject RIV: CD - Macromolecular Chemistry

  16. Spectroscopic study of thermoresponsive block copolymers in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří; Čadová, Eva

    Amsterdam: Elsevier, 2015. P116. [International Colloids Conference /5./. 21.06.2015-24.06.2015, Amsterdam] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : thermoresponsive polymer * block copolymer * poly(N-isopropylacrylamide) Subject RIV: CD - Macromolecular Chemistry

  17. Manipulating Interfaces through Surface Confinement of Poly(glycidyl methacrylate)-block-poly(vinyldimethylazlactone), a Dually Reactive Block Copolymer

    International Nuclear Information System (INIS)

    The assembly of dually reactive, well-defined diblock copolymers incorporating the chemoselective/functional monomer, 4,4-dimethyl-2-vinylazlactone (VDMA) and the surface-reactive monomer glycidyl methacrylate (GMA) is examined to understand how competition between surface attachment and microphase segregation influences interfacial structure. Reaction of the PGMA block with surface hydroxyl groups not only anchors the copolymer to the surface, but limits chain mobility, creating brush-like structures comprising PVDMA blocks, which contain reactive azlactone groups. The block copolymers are spin coated at various solution concentrations and annealed at elevated temperature to optimize film deposition to achieve a molecularly uniform layer. The thickness and structure of the polymer thin films are investigated by ellipsometry, infrared spectroscopy, and neutron reflectometry. The results show that deposition of PGMA-b-PVDMA provides a useful route to control film thickness while preserving azlactone groups that can be further modified with biotin-poly(ethylene glycol)amine to generate designer surfaces. The method described herein offers guidance for creating highly functional surfaces, films, or coatings through the use of dually reactive block copolymers and postpolymerization modification.

  18. Novel multiarm star block copolymer ionomers as proton conductive membranes

    OpenAIRE

    Demirel, Adem Levent; Erdoğan, Tuba; Bilir, Çiğdem; Ünveren, Elif; Tunca, Ümit

    2014-01-01

    A series of well-defined novel multiarm star block copolymer ionomers with an average of 6, 11 and 15 arms, sulfonated polystyrene-block-poly(2,2,3,3,3-pentafluoropropyl methacrylate) (SPS-b-PFPMA), were prepared via a combination of atom transfer radical polymerization (ATRP), Diels–Alder click reaction and postsulfonation reaction. First, multiarm star polymer with anthracene functionality as reactive periphery groups was prepared by a cross-linking reaction of divinyl benzene using ?-anthr...

  19. Functional Block Copolymers as Compatibilizers for Nanoclays in Polypropylene Nanocomposites

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Daugaard, Anders Egede; Stribeck, Norbert;

    With the aim of creating tough nanocomposits (NC) [1] based on polypropylene (PP) and nanoclay (NCl) in the framework of the 7th EU program NANOTOUGH we have designed amphiphilic block copolymers utilizing Atom Transfer Radical Polymerization (ATRP) [2]. They consist of a hydrophobic block of...... PP (by its crystallites) is replaced by alien-reinforcement (of the MMT). Furthermore, the results from the impact strength and cyclic test of the prepared PP nanocomposites [3] are promicing....

  20. Polystyrene-b-polyethylene oxide block copolymer membranes, methods of making, and methods of use

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-04-16

    Embodiments of the present disclosure provide for polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer nanoporous membranes, methods of making a PS-b-PEO block copolymer nanoporous membrane, methods of using PS-b-PEO block copolymer nanoporous membranes, and the like.

  1. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    Science.gov (United States)

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  2. Influence of melt processing induced orientation on the morphology and mechanical properties of poly(styrene-b-ethylene/butylene-b-styrene) block copolymers and their composites with graphite

    International Nuclear Information System (INIS)

    Highlights: • Orientation was induced during processing of SEBS, SEBS-MA and their composites. • Static and dynamic mechanical tests in perpendicular directions were performed. • 400–1600% difference in Young’s or storage modulus in function of orientation. • Micro/nanoscale morphology and orientation investigated by POM, SEM and AFM. • A method to improve the mechanical behavior by morphology control was proposed. - Abstract: The effect of orientation induced during the manufacturing process on the self-assembled morphology and mechanical properties of poly(styrene-b-ethylene/butylene-b-styrene) block copolymer (SEBS), maleated SEBS (SEBS-MA) and their composites with graphite was examined in this paper. The roll milling process induced higher stiffness along the rolling direction, emphasized by the increase of Young’s modulus with 645% in this direction relative to the perpendicular one and the increase of storage modulus at room temperature with one order of magnitude. The addition of graphite particles diminished the anisotropy of static and dynamic mechanical properties but contributed to the increase of the total energy absorbed till break. The different self-assembled morphologies and degree of order observed by polarized optical microscopy (POM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) in SEBS and SEBS-MA explained some of the differences in their static and dynamic mechanical behavior. For the first time the anisotropy was emphasized by the different glass transition values obtained on the two stretching directions

  3. Stereo block copolymers of L- and D-lactides

    OpenAIRE

    Yui, Nobuhiko; Pieter J. Dijkstra; Feijen, Jan

    1990-01-01

    Sequential diblock copolymers composed of L- and D-lactic acid residues were synthesized through a living ring-opening polymerization of L- and D-lactide initiated by aluminium tris(2-propanolate). The composition of the block copolymers was varied by changing the reaction conditions and monomer over initiator ratio and confirmed by 1H NMR analysis, molecular weight determination and optical rotation measurements. Molecular weights ranged from 1,3 to 2,0 · 104 with 1,2 < Mw/Mn < 1,4. Stereoco...

  4. Polymers and block copolymers of fluorostyrenes by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Borkar, Sachin; Abildgaard, Lillian; Georgieva, V.; Siesler, H.W.; Jankova, Katja Atanassova

    2002-01-01

    Fully or partly fluorinated polymers have many desirable and intriguing properties. In the framework of a larger program on design and control of new functional block copolymers we recently employed the Atom Transfer Radical Polymerization (ATRP) protocol on 2,3,4,5,6-pentafluorostyrene (FS). We...... materials based on 2,3,5,6-tetrafiuoro-4-methoxy-styrene (TFMS). TFMS homopolymers as well as diblock copolymers with FS are produced by ATRP. Both types of novel polymers were subsequently demethylated and different side chains introduced on the resulting hydroxy sites....

  5. Block copolymer-nanoparticle hybrid self-assembly

    KAUST Repository

    Hoheisel, Tobias N.

    2015-01-01

    © 2014 Published by Elsevier Ltd. Polymer-inorganic hybrid materials provide exciting opportunities as they may display favorable properties from both constituents that are desired in applications including catalysis and energy conversion and storage. For the preparation of hybrid materials with well-defined morphologies, block copolymer-directed nanoparticle hybrids present a particularly promising approach. As will be described in this review, once the fundamental characteristics for successful nanostructure formation at or close to the thermodynamic equilibrium of these nanocomposites are identified, the approach can be generalized to various materials classes. In addition to the discussion of recent materials developments based on the use of AB diblock copolymers as well as ABC triblock terpolymers, this review will therefore emphasize progress in the fundamental understanding of the underlying formation mechanisms of such hybrid materials. To this end, critical experiments for, as well as theoretical progress in the description of these nanostructured block copolymer-based hybrid materials will be discussed. Rather than providing a comprehensive overview, the review will emphasize work by the Wiesner group at Cornell University, US, on block copolymer-directed nanoparticle assemblies as well as their use in first potential application areas. The results provide powerful design criteria for wet-chemical synthesis methodologies for the generation of functional nanomaterials for applications ranging from microelectronics to catalysis to energy conversion and storage.

  6. Design and Application of Nanoscale Actuators Using Block-Copolymers

    Directory of Open Access Journals (Sweden)

    Paul D. Topham

    2010-10-01

    Full Text Available Block copolymers are versatile designer macromolecules where a “bottom-up” approach can be used to create tailored materials with unique properties. These simple building blocks allow us to create actuators that convert energy from a variety of sources (such as chemical, electrical and heat into mechanical energy. In this review we will discuss the advantages and potential pitfalls of using block copolymers to create actuators, putting emphasis on the ways in which these materials can be synthesised and processed. Particular attention will be given to the theoretical background of microphase separation and how the phase diagram can be used during the design process of actuators. Different types of actuation will be discussed throughout.

  7. Formation and Characterization of Anisotropic Block Copolymer Gels

    Science.gov (United States)

    Liaw, Chya Yan; Joester, Derk; Burghardt, Wesley; Shull, Kenneth

    2012-02-01

    Cylindrical micelles formed from block copolymer solutions closely mimic biological fibers that are presumed to guide mineral formation during biosynthesis of hard tissues like bone. The goal of our work is to use acrylic block copolymers as oriented templates for studying mineral formation reactions in model systems where the structure of the underlying template is well characterized and reproducible. Self-consistent mean field theory is first applied to investigate the thermodynamically stable micellar morphologies as a function of temperature and block copolymer composition. Small-angle x-ray scattering, optical birefringence and shear rheometry are used to study the morphology development during thermal processing. Initial experiments are based on a thermally-reversible alcohol-soluble system that can be converted to an aqueous gel by hydrolysis of a poly(t-butyl methacrylate) block to a poly(methacrylic acid) block. Aligned cylindrical domains are formed in the alcohol-based system when shear is applied in an appropriate temperature regime, which is below the critical micelle temperature but above the temperature at which the relaxation time of the gels becomes too large. Processing strategies for producing the desired cylindrical morphologies are being developed that account for both thermodynamic and kinetic effects.

  8. Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers

    Science.gov (United States)

    Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash

    2013-03-01

    Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

  9. Synthesis and interactions with blood of polyetherurethaneurea/polypeptide block copolymers.

    Science.gov (United States)

    Ito, Y; Miyashita, K; Kashiwagi, T; Imanishi, Y

    1993-01-01

    Polyurethane/polypeptide block copolymers were synthesized. Infrared spectroscopy and differential scanning calorimetry revealed that in the block copolymers both segments undergo phase-mixing, while in polyurethane/polypeptide blend both components undergo phase-separation. Contact angle measurement showed that in the block copolymers polyurethane segments tended to appear on the membrane surface, whereas in polyurethane/polypeptide blend polypeptide components appeared on the membrane surface. In vitro nonthrombogenicity of the block copolymers was similar to that of homopolymers or polymer blends, though adhesion and deformation of platelets were suppressed on the block copolymer membranes. PMID:8260582

  10. Heat Capacity of Spider Silk-like Block Copolymers

    OpenAIRE

    Huang, Wenwen; Krishnaji, Sreevidhya; Hu, Xiao; Kaplan, David; Cebe, Peggy

    2011-01-01

    We synthesized and characterized a new family of di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n=1–3), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition, Tg, were measured by temperature modulated differential scanning calorimetry. For the solid sta...

  11. Self-assembly of Block and Graft Copolymers in Aerosol Nanoparticles

    OpenAIRE

    Rahikkala, Antti

    2015-01-01

    This study examined how to control the self-assembly of block and graft copolymers during the aerosol process, which produces nanoparticles with phase-separated inner structure and phase dimensions ranging from 3 nm to 30 nm. The nanoparticles were also studied for the possibility of their use as a drug carriers. Block copolymers consist of two or more chemically different polymer blocks covalently bound together. In graft copolymers molecules are bound as side-chains to the copolymer backbon...

  12. The Synthesis, Self-Assembly and Self-Organisation of Polysilane Block Copolymers

    OpenAIRE

    Holder, Simon J.; Jones, Richard G.

    2008-01-01

    Block copolymers containing polysilane blocks are unique in that the polysilane components possess electro-active properties and are readily photodegradable. This review will discuss and assess the two major approaches to the synthesis of polysilane block copolymers via pre-formed polymer chain coupling and living polymerisation techniques. The self-organisation of polysilane block copolymers and the morphologies adopted in thin films are reviewed. Amphiphilic polysilane-containing block copo...

  13. Adsorption of polyelectrolytes and charged block copolymers on oxides. Consequences for colloidal stability.

    OpenAIRE

    Hoogeveen, N.G.

    1996-01-01

    The aim of the study described in this thesis was to examine the adsorption properties of polyelectrolytes and charged block copolymers on oxides, and the effect of these polymers on the colloidal stability of oxidic dispersions. For this purpose the interaction of some well-characterised polyelectrolytes and block copolymers with oxidic substrates has been systematically studied. A set of block copolymers with one charged block and one neutral water-soluble block had to be synthesised becaus...

  14. Biocompatibility of epoxidized styrene-butadiene-styrene block copolymer membrane

    International Nuclear Information System (INIS)

    Styrene-butadiene-styrene block copolymer (SBS) membrane was prepared by solution casting method and then was epoxidized with peroxyformic acid generated in situ to yield the epoxidized styrene-butadiene-styrene block copolymer membrane (ESBS). The structure and properties of ESBS were characterized with infrared spectroscopy, Universal Testing Machine, differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The performances of contact angle, water content, protein adsorption, and water vapor transmission rate on ESBS membrane were determined. After epoxidation, the hydrophilicity of the membrane increased. The water vapor transmission rate of ESBS membrane is similar to human skin. The biocompatibility of ESBS membrane was evaluated with the cell culture of fibroblasts on the membrane. It revealed that the cells not only remained viable but also proliferated on the surface of the various ESBS membranes and the population doubling time for fibroblast culture decreased.

  15. Novel block, graft and random copolymers for biomedical applications

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Tanaka, Masaru;

    Despite the simple structure, poly(2-methoxyethyl acrylate) (PMEA) shows excellent blood compatibility [1]. Both the freezing-bound water (intermediate water: preventing the biocomponents from directly contacting the polymer surface) and non-freezing water on the polymer surface play important ro...... copolymers with MMA [4] utilizing ATRP. Here we present other block, graft and random copolymers of MEA intended for biomedical applications. These macromolecular architectures have been constructed by employing controlled radical polymerization methods such as RAFT and ATRP....... roles for this [2]. An artificial lung (oxygenator), already in use, is coated with high MW PMEA prepared by radical polymerization with AIBN [2]. To broaden the possibilities for designing biomedical devices [3] and inspired from these findings we first prepared homo polymers of MEA and their block...

  16. Preparation of Pickering Double Emulsions Using Block Copolymer Worms

    OpenAIRE

    Thompson, Kate L.; Mable, Charlotte J.; Lane, Jacob A.; Derry, Mathew J.; Fielding, Lee A.; Armes, Steven P.

    2015-01-01

    The rational formulation of Pickering double emulsions is described using a judicious combination of hydrophilic and hydrophobic block copolymer worms as highly anisotropic emulsifiers. More specifically, RAFT dispersion polymerization was utilized to prepare poly(lauryl methacrylate)–poly(benzyl methacrylate) worms at 20% w/w solids in n-dodecane and poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate)–poly(benzyl methacrylate) worms at 13% w/w solids in water by polymerization...

  17. Transient instability upon temperature quench in weakly ordered block copolymers

    OpenAIRE

    Qi, Shuyan; Wang, Zhen-Gang

    1999-01-01

    We report a novel transient instability upon temperature quench in weakly ordered block copolymer microphases possessing a soft direction or directions, such as the lamellar and hexagonal cylinder (HEX) phases. We show that reequilibration of the order parameter is accompanied by transient long wavelength undulation of the layers or cylinders—with an initial wavelength that depends on the depth of the temperature quench—that eventually disappears as the structure reaches its equilibrium at th...

  18. Host-Guest Self-assembly in Block Copolymer Blends

    OpenAIRE

    Woon Ik Park; YongJoo Kim; Jae Won Jeong; Kyungho Kim; Jung-Keun Yoo; Yoon Hyung Hur; Jong Min Kim; Thomas, Edwin L.; Alfredo Alexander-Katz; Yeon Sik Jung

    2013-01-01

    Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (...

  19. Block and Graft Copolymers Containing Carboxylate or Phosphonate Anions

    OpenAIRE

    Hu, Nan

    2014-01-01

    This dissertation focuses on synthesis and characterization of graft and block copolymers containing carboxylate or phosphonate anions that are potential candidates for biomedical applications such as drug delivery and dental adhesives. Ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate monomers were synthesized based on aza-Michael addition reactions. Free radical copolymerizations of these monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer...

  20. Electrically Tunable Soft-Solid Block Copolymer Structural Color.

    Science.gov (United States)

    Park, Tae Joon; Hwang, Sun Kak; Park, Sungmin; Cho, Sung Hwan; Park, Tae Hyun; Jeong, Beomjin; Kang, Han Sol; Ryu, Du Yeol; Huh, June; Thomas, Edwin L; Park, Cheolmin

    2015-12-22

    One-dimensional photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid (IL) swollen block copolymer (BCP) films. Placement of a polymer/ionic liquid film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2-vinylpyridine) (PS-b-QP2VP) copolymer SC film allowed the development of red (R), green (G), and blue (B) full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3 to +6 V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device. PMID:26505787

  1. Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2014-04-01

    Full Text Available Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells.

  2. Preparation and icephobic properties of polymethyltrifluoropropylsiloxane–polyacrylate block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaohui; Zhao, Yunhui [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Li, Hui [School of Chemistry and Chemical Engineering, Shandong Key Laboratory of Fluorine Chemistry and Chemical Engineering Materials, University of Jinan, Jinan 250022 (China); Yuan, Xiaoyan, E-mail: xyuan28@yahoo.com [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2014-10-15

    Highlights: • PMTFPS–b-polyacrylate copolymers in five different compositions were synthesized. • Enrichment of PMTFPS amounts at the surface made high F/Si value. • Icing delay time was related to the surface roughness. • Ice shear strength was decreased by the synergistic effect of silicone and fluorine. - Abstract: Five polymethyltrifluoropropylsiloxane (PMTFPS)–polyacrylate block copolymers (PMTFPS–b-polyacrylate) were synthesized by free radical polymerization of methyl methacrylate, n-butyl acrylate and hydroxyethyl methacrylate using PMTFPS macroazoinitiator (PMTFPS-MAI) in range of 10–50 mass percentages. The morphology, surface chemical composition and wettability of the prepared copolymer films were investigated by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and water contact angle measurement. Delayed icing time and ice shear strength of the films were also detected for the icephobic purpose. The surface morphologies of the copolymers were different from those of the bulk because of the migration of the PMTFPS segments to the air interface during the film formation. Maximal delayed icing time (186 s at −15 °C) and reduction of the ice shear strength (301 ± 10 kPa) which was significantly lower than that of polyacrylates (804 ± 37 kPa) were achieved when the content of PMTFPS-MAI was 20 wt%. The icephobicity of the copolymers was attributed primarily to the enrichment of PMTFPS on the film surface and synergistic effect of both silicone and fluorine. Thus, the results show that the PMTFPS–b-polyacrylate copolymer can be used as icephobic coating materials potentially.

  3. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly

    OpenAIRE

    Li, Zihui; Sai, Hiroaki; Warren, Scott C.; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M.; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm P...

  4. Redox-controlled micellization of organometallic block copolymers.

    Science.gov (United States)

    Rider, David A; Winnik, Mitchell A; Manners, Ian

    2007-11-21

    Polystyrene-block-polyferrocenylsilane (PS-b-PFS) diblock copolymers were stoichiometrically oxidized in solution using salts of the one-electron oxidant tris(4-bromophenyl)ammoniumyl. Due to a redox-induced polarity change for the PFS block, self-assembly into well-defined spherical micelles occurs. The micelles are composed of a core of partially oxidized PFS segments and a corona of PS. When the micellar solutions were treated with the reducing agent decamethylcobaltocene, the spherical micelles disassemble and regenerate unassociated and pristine PS-b-PFS free chains. PMID:17971963

  5. Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores

    Directory of Open Access Journals (Sweden)

    Takaomi Kobayashi

    2010-01-01

    Full Text Available Photoresponsive block copolymers (PRBCs containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films.

  6. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

    2014-11-25

    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins. PMID:25393374

  7. Block copolymers for alkaline fuel cell membrane materials

    Science.gov (United States)

    Li, Yifan

    Alkaline fuel cells (AFCs) using anion exchange membranes (AEMs) as electrolyte have recently received considerable attention. AFCs offer some advantages over proton exchange membrane fuel cells, including the potential of non-noble metal (e.g. nickel, silver) catalyst on the cathode, which can dramatically lower the fuel cell cost. The main drawback of traditional AFCs is the use of liquid electrolyte (e.g. aqueous potassium hydroxide), which can result in the formation of carbonate precipitates by reaction with carbon dioxide. AEMs with tethered cations can overcome the precipitates formed in traditional AFCs. Our current research focuses on developing different polymer systems (blend, block, grafted, and crosslinked polymers) in order to understand alkaline fuel cell membrane in many aspects and design optimized anion exchange membranes with better alkaline stability, mechanical integrity and ionic conductivity. A number of distinct materials have been produced and characterized. A polymer blend system comprised of poly(vinylbenzyl chloride)-b-polystyrene (PVBC-b-PS) diblock copolymer, prepared by nitroxide mediated polymerization (NMP), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or brominated PPO was studied for conversion into a blend membrane for AEM. The formation of a miscible blend matrix improved mechanical properties while maintaining high ionic conductivity through formation of phase separated ionic domains. Using anionic polymerization, a polyethylene based block copolymer was designed where the polyethylene-based block copolymer formed bicontinuous morphological structures to enhance the hydroxide conductivity (up to 94 mS/cm at 80 °C) while excellent mechanical properties (strain up to 205%) of the polyethylene block copolymer membrane was observed. A polymer system was designed and characterized with monomethoxy polyethylene glycol (mPEG) as a hydrophilic polymer grafted through substitution of pendent benzyl chloride groups of a PVBC

  8. Biodegradable PELA block copolymers: in vitro degradation and tissue reaction.

    Science.gov (United States)

    Younes, H; Nataf, P R; Cohn, D; Appelbaum, Y J; Pizov, G; Uretzky, G

    1988-01-01

    Degradation of, and tissue reaction elicited by a series of polyethylene oxide (PEO)/polylactic acid (PLA) PELA block copolymers were studied in vitro and in vivo. In particular, the effect of pH, temperature and enzymatic activity was addressed. The mass loss was faster, the more basic the media, while, expectedly, PELA copolymers degraded faster with the higher temperature. The addition of an enzyme (carboxylic ester hydrolase) had no effect. The degradation process strongly affected the mechanical properties of the materials under investigation, the elongation at break dropping drastically after two days of degradation. After seven days, only gross observation of the extensively degraded samples was possible. The in vivo studies compared the tissue reaction elicited by various PELA copolymers to that evoked by PLA. Evaluation of tissue reaction observed with a PELA sample after sterilization with gamma radiation showed acute inflammation with considerable dispersion of the material, 12 days after implantation. The granulomatous reaction observed with PELA copolymers after ethylene oxide sterilization was identical to the reaction observed with PLA. PMID:3064826

  9. Diamond-Forming Block Copolymers and Diamond-like Morphologies: a New Route towards efficient Block Copolymer Membranes?

    Science.gov (United States)

    Erukhimovich, Igor; Kriksin, Yury

    2014-03-01

    Formation of ordered (microphase separated) block copolymer nanostructures is a promising route towards creating isoporous membranes suitable for technological applications. We propose a new route to achieve this target: to choose such block copolymer architectures, which would provide a practically isotropic permeability both in the bulk and in thin films. Basing both on the weak segregation theory extension into the thin films and the self-consistent field theory numerical procedure we present the results concerning the effects of the wall confinement both with neutral, selective and patterned walls on the structure and stability of the block copolymer ordered films. The diamond-like morphology is found to be the most promising one as to optimizing the permeability of thin films. A new effect of the diamond morphology stability enhancement in the presence of a properly designed lamellar-like wall pattern is discovered and the corresponding phase diagram demonstrating the effect of the pattern scale and film width on the diamond morphology stability is presented. The financial support was provided by Ministry of Science and Education of Russian Federation (State Contract No. 02.740.11.0858) and European Commission (FP7 project NMP3-SL-2009- 228652 (SELFMEM)).

  10. Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

    Science.gov (United States)

    2016-01-01

    Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers. PMID:27134312

  11. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.

    Science.gov (United States)

    Li, Zihui; Sai, Hiroaki; Warren, Scott C; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules. PMID:21103025

  12. Synthesis of segmented PB(SMA-block-PB)(n) block copolymers through a polymeric iniferter technique

    NARCIS (Netherlands)

    Kroeze, E; ten Brinke, G.; Hadziioannou, G

    1997-01-01

    A technique is described for the synthesis of segmented block copolymers of polybutadiene and poly(styrene-co-maleic anhydride) through a polymeric therma iniferter based on polybutadiene, which was used as an initiator for the thermal copolymerization of styrene and maleic anhydride. The polymeric

  13. Hybrid - block copolymer nanocomposites. characterization of nanostructure by small-angle X-ray scattering (SAXS)

    OpenAIRE

    A. Romo-Uribe

    2007-01-01

    The nanoscopic order of a series of block copolymer-inorganic nanocomposites was characterized using small-angle X-ray scattering (SAXS). The nanostructures were obtained via a diblock copolymer directed sol-gel synthesis. The copolymer consists of blocks of poly(isoprene) -PI- and blocks of poly(ethylene oxide) -PEO. The inorganic material consists of a crosslinked sol of 3-glycidoxypropyltrimethoxysilane and aluminum-tri-sec-butoxide in a 4:1 mole ratio, to generate an aluminosilicate ceram...

  14. High aspect ratio sub-15 nm silicon trenches from block copolymer templates.

    Science.gov (United States)

    Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Chourou, S T; Hong, Sung Woo; Olynick, Deirdre L; Russell, Thomas P

    2012-11-01

    High-aspect-ratio sub-15-nm silicon trenches are fabricated directly from plasma etching of a block copolymer mask. A novel method that combines a block copolymer reconstruction process and reactive ion etching is used to make the polymer mask. Silicon trenches are characterized by various methods and used as a master for subsequent imprinting of different materials. Silicon nanoholes are generated from a block copolymer with cylindrical microdomains oriented normal to the surface. PMID:22903820

  15. Microtome Sliced Block Copolymers and Nanoporous Polymers as Masks for Nanolithography

    OpenAIRE

    Shvets, Violetta; Schulte, Lars; Ndoni, Sokol

    2014-01-01

    Introduction. Block copolymers self-assembling properties are commonly used for creation of very fine nanostructures [1]. Goal of our project is to test new methods of the block-copolymer lithography mask preparation: macroscopic pieces of block-copolymers or nanoporous polymers with cross-linked phase are sliced with microtome and pattern is transfered from flakes to substrate by plasma etching.Experimental Section. Group of Self-organized Nanoporous Materials in Technical University of Denm...

  16. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  17. Designing block copolymer architectures for targeted membrane performance

    KAUST Repository

    Dorin, Rachel Mika

    2014-01-01

    Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume fractions but varying in total molar mass from 43 kg/mol to 115 kg/mol to systematically study the effect of polymer size on membrane structure. Small-angle X-ray scattering was used to probe terpolymer solution structure in the dope. All four triblocks displayed solution scattering patterns consistent with a body-centered cubic morphology. After membrane formation, structures were characterized using a combination of scanning electron microscopy and filtration performance tests. Membrane pore densities that ranged from 4.53 × 1014 to 1.48 × 1015 pores/m 2 were observed, which are the highest pore densities yet reported for membranes using self-assembly and non-solvent induced phase separation. Hydraulic permeabilities ranging from 24 to 850 L m-2 h-1 bar-1 and pore diameters ranging from 7 to 36 nm were determined from permeation and rejection experiments. Both the hydraulic permeability and pore size increased with increasing molar mass of the parent terpolymer. The combination of polymer characterization and membrane transport tests described here demonstrates the ability to rationally design macromolecular structures to target specific performance characteristics in block copolymer derived ultrafiltration membranes. © 2013 Elsevier Ltd. All rights reserved.

  18. A concise review of dynamical processes in polymorphic environments of a block copolymer: Rotational diffusion and photoisomerization

    Indian Academy of Sciences (India)

    K S Mali; G B Dutt

    2007-03-01

    This article describes our ongoing efforts to understand dynamical processes such as rotational diffusion and photoisomerization in polymorphic environments of a block copolymer. The objective is to explore how the typical properties of a block copolymer solution such as critical micelle temperature (CMT) and temperature-induced sol-gel transition influence the rotational diffusion of hydrophobic solute molecules. Rotational diffusion of solute molecules differs significantly below and above the CMT of a block copolymer solution, while there is no influence of sol-gel transition on solute rotation. This is rationalized on the basis of the site of solubilization of the solute molecules which is the palisade layer of the micelles in both phases and unaffected by gelation. A similar result has been obtained in case of photoisomerization studies carried out with a carbocyanine derivative in the sol and gel phases of the block copolymer. The isomerization studies have been extended to the reverse phases (sol and gel phases) of the block copolymer to explore the nature of the water present in the cores of the reverse micelles. Our results provide evidence for the existence of water droplets with properties resembling bulk water. In essence, we show that despite having vastly differing bulk properties, both the solution and gel phases (normal as well as reverse) offer identical microscopic environment.

  19. Self-assembly of block copolymers on topographically patterned polymeric substrates

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Park, Soojin; Lee, Dong Hyun; Xu, Ting

    2016-05-10

    Highly-ordered block copolymer films are prepared by a method that includes forming a polymeric replica of a topographically patterned crystalline surface, forming a block copolymer film on the topographically patterned surface of the polymeric replica, and annealing the block copolymer film. The resulting structures can be used in a variety of different applications, including the fabrication of high density data storage media. The ability to use flexible polymers to form the polymeric replica facilitates industrial-scale processes utilizing the highly-ordered block copolymer films.

  20. Characterization and micellization of a poloxamer block copolymer

    DEFF Research Database (Denmark)

    Hvidt, S.; Pedersen, Walther Batsberg

    2007-01-01

    Several poloxamers that are symmetrical EPE block copolymers (E and P are ethylene and propylene oxide, respectively) have been characterized by size exclusion chromatography on Superose columns in water. The poloxamers contain between 12 and 26 wt% of smaller-size UV-absorbing impurities....... Poloxamer P94 (E28P48E28) forms micelles with increasing temperature, and micellization was investigated by eluent gel permeation chromatography (EGPC). EGPC results demonstrate that P94 impurities are not incorporated into the micelles up to 38°C. The importance of poloxamer heterogeneity for thermodynamic...

  1. Self-assembly in casting solutions of block copolymer membranes

    KAUST Repository

    Marques, Debora S.

    2013-01-01

    Membranes with exceptional pore regularity and high porosity were obtained from block copolymer solutions. We demonstrate by small-angle X-ray scattering that the order which gives rise to the pore morphology is already incipient in the casting solution. Hexagonal order was confirmed in PS-b-P4VP 175k-b-65k solutions in DMF/THF/dioxane with concentrations as high as 24 wt%, while lamellar structures were obtained in more concentrated solutions in DMF or DMF/dioxane. The change in order has been understood with the support of dissipative particle dynamic modeling. © 2013 The Royal Society of Chemistry.

  2. Perspective: Evolutionary design of granular media and block copolymer patterns

    Science.gov (United States)

    Jaeger, Heinrich M.; de Pablo, Juan J.

    2016-05-01

    The creation of new materials "by design" is a process that starts from desired materials properties and proceeds to identify requirements for the constituent components. Such process is challenging because it inverts the typical modeling approach, which starts from given micro-level components to predict macro-level properties. We describe how to tackle this inverse problem using concepts from evolutionary computation. These concepts have widespread applicability and open up new opportunities for design as well as discovery. Here we apply them to design tasks involving two very different classes of soft materials, shape-optimized granular media and nanopatterned block copolymer thin films.

  3. Effect of block composition on thermal properties and melt viscosity of poly[2-(dimethylaminoethyl methacrylate], poly(ethylene oxide and poly(propylene oxide block co-polymers

    Directory of Open Access Journals (Sweden)

    2011-09-01

    Full Text Available To modify the rheological properties of certain commercial polymers, a set of block copolymers were synthesized through oxyanionic polymerization of 2-(dimethylaminoethyl methacrylate to the chain ends of commercial prepolymers, namely poly(ethylene oxide (PEO, poly(ethylene oxide-block-poly(propylene oxide-block-poly(ethylene oxide (PEO-PPO-PEO, and poly(propylene oxide (PPO. The formed block copolymers were analysed with size exclusion chromatography and nuclear magnetic resonance spectroscopy in order to confirm block formation. Thermal characterization of the resulting polymers was done with differential scanning calorimetry. Thermal transition points were also confirmed with rotational rheometry, which was primarily used to measure melt strength properties of the resulting block co-polymers. It was observed that the synthesised poly[2-(dimethylaminoethyl methacrylate]-block (PDM affected slightly the thermal transition points of crystalline PEO-block but the influence was stronger on amorphous PPO-blocks. Frequency sweeps measured above the melting temperatures for the materials confirmed that the pre-polymers (PEO and PEO-PPO-PEO behave as Newtonian fluids whereas polymers with a PDM block structure exhibit clear shear thinning behaviour. In addition, the PDM block increased the melt viscosity when compared with that one of the pre-polymer. As a final result, it became obvious that pre-polymers modified with PDM were in entangled form, in the melted state as well in the solidified form.

  4. (Electro)Mechanical Properties of Olefinic Block Copolymers

    Science.gov (United States)

    Spontak, Richard

    2014-03-01

    Conventional styrenic triblock copolymers (SBCs) swollen with a midblock-selective oil have been previously shown to exhibit excellent electromechanical properties as dielectric elastomers. In this class of electroactive polymers, compliant electrodes applied as active areas to opposing surfaces of an elastomer attract each other, and thus compress the elastomer due to the onset of a Maxwell stress, upon application of an external electric field. This isochoric process is accompanied by an increase in lateral area, which yields the electroactuation strain (measuring beyond 300% in SBC systems). Performance parameters such as the Maxwell stress, transverse strain, dielectric breakdown, energy density and electromechanical efficiency are determined directly from the applied electric field and resulting electroactuation strain. In this study, the same principle used to evaluate SBC systems is extended to olefinic block copolymers (OBCs), which can be described as randomly-coupled multiblock copolymers that consist of crystallizable polyethylene hard segments and rubbery poly(ethylene-co-octene) soft segments. Considerations governing the development of a methodology to fabricate electroresponsive OBC systems are first discussed for several OBCs differing in composition and bulk properties. Evidence of electroactuation in selectively-solvated OBC systems is presented and performance metrics measured therefrom are quantitatively compared with dielectric elastomers derived from SBC and related materials.

  5. Tough Block Copolymer Organogels and Elastomers as Short Fiber Composites

    Science.gov (United States)

    Kramer, Edward J.

    2012-02-01

    The origins of the exceptional toughness and elastomeric properties of gels and elastomers from block copolymers with semicrystalline syndiotactic polypropylene blocks will be discussed. Using synchrotron X-radiation small angle (SAXS) and wide angle X-ray scattering (WAXS) experiments were simultaneously performed during step cycle tensile deformation of these elastomers and gels. From these results the toughness can be attributed to the formation, orientation and elongation of the crystalline fibrils along the tensile direction. The true stress and true strain ɛH during each cycle were recorded, including the true strain at zero load ɛH,p after each cycle that resulted from the plastic deformation of the sPP crystals in the gel or elastomer. The initial Young's modulus Einit and maximum tangent modulus Emax in each cycle undergo dramatic changes as a function of ɛH,p, with Einit decreasing for ɛH,p 100 to 1000 at the highest maximum (nominal) strain. Based on SAXS patterns from the deformed and relaxed gels, as well as on previous results on deformation of semicrystalline random copolymers by Strobl and coworkers, we propose that the initial decrease in Einit and increase in Emax with ɛH,p are due to a breakup of the network of the original sPP crystal lamellae and the conversion of the sPP lamellae into fibrils whose aspect ratio increases with further plastic deformation, respectively. The gel elastic properties can be understood quantitatively as those of a short fiber composite with a highly deformable matrix. At zero stress the random copolymer midblock chains that connect the fibrils cause these to make all angles to the tensile axis (low Einit), while at the maximum strain the stiff, crystalline sPP fibrils align with the tensile axis producing a strong, relatively stiff gel. The evolution of the crystalline structure during deformation is confirmed by WAXS and FTIR measurements.

  6. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  7. Controlling thermochromism in a photonic block copolymer gel.

    Science.gov (United States)

    Walish, Joseph J; Fan, Yin; Centrone, Andrea; Thomas, Edwin L

    2012-09-26

    The tunable properties of stimulus-responsive materials attract great interest in a variety of technological applications. Photonic gels are a new class of these materials, which can be tuned to reflect different wavelengths of light. Controlling this reflected color via temperature-induced changes of self-assembled photonic materials is important for their application in sensors and displays. In this work, the thermochromic behavior of a PS-P2VP photonic gel was found to originate from a temperature-induced change in the pK(a) of the P2VP blocks. Control was obtained through the manipulation of the solution pH. The findings of this work provide the basis for understanding and controlling the properties of thermochromic block copolymers fostering their use in technologically relevant applications. PMID:22763921

  8. Chirality in block copolymer melts: mesoscopic helicity from intersegment twist.

    Science.gov (United States)

    Zhao, Wei; Russell, Thomas P; Grason, Gregory M

    2013-02-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self-consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesoscopically chiral phases are stable: an undulated lamellar phase and a phase of hexagonally ordered helices. We show that the nonlinear sensitivity of mesoscale chiral order to preferred pitch derives specifically from the geometric and thermodynamic coupling of the helical mesodomain shape to the twisted packing of chiral segments within the core, giving rise to a second-order cylinder-to-helix transition. PMID:23414052

  9. Characterizing the interfaces of block copolymers with high χ

    Science.gov (United States)

    Sunday, Daniel; Maher, Michael; Blachut, Gregory; Asano, Yusuke; Tein, Summer; Willson, C. Grant; Ellison, Christopher; Kline, R. Joseph

    In order for block copolymer (BCP) directed self-assembly (DSA) to be able to pattern features below 10 nm there must be materials which can spontaneously assembly at the required length scales. For the smallest features this will require phase separation where the total chain lengths are under 50 monomer units, demanding very large interaction parameters (χ) to have an order-disorder transition. One of the key parameters for DSA will be the interfacial width between the blocks, which is expected to be correlated to the interaction parameter and will help determine the line edge roughness (LER). We have used resonant soft X-ray reflectivity to investigate a series of high χ BCPs with different compositions and molecular weights to determine the interfacial width and degree of phase separation. We use these results to estimate the value of χ and determine relationships between χ and the interfacial mixing.

  10. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    KAUST Repository

    Yu, Haizhou

    2015-10-16

    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  11. Transport of Water in Semicrystalline Block Copolymer Membranes

    Science.gov (United States)

    Hallinan, Daniel; Oparaji, Onyekachi

    Poly(styrene)-block-poly(ethylene oxide) (PS- b-PEO) is a semicrystalline block copolymer (BCP) with interesting properties. It is mechanically tough, amphiphilic, and has a polar phase. The mechanical toughness is due to the crystallinity of PEO and the high glass transition temperature of PS, as well as the morphological structure of the BCP. The polymer has high CO2, water, and salt solubility that derive from the polar PEO component. Potential applications include CO2 separation, water purification, and lithium air batteries. In all of the aforementioned applications, water transport is an important parameter. The presence of water can also affect thermal and mechanical properties. Water transport and thermal and mechanical properties of a lamellar PS- b-PEO copolymer have been measured as a function of water activity. Water transport can be affected by the heterogeneous nature of a semicrystalline BCP. Therefore, Fourier transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy has been employed, because water transport and polymer swelling can be measured simultaneously. The effect of BCP structure on transport has been investigated by comparing water transport in PS- b-PEO to a PEO homopolymer. The crystalline content of the PEO and the presence of glassy PS lamellae will be used to explain the transport results.

  12. Topology and Shape Control for Assemblies of Block Copolymer Blends in Solution

    KAUST Repository

    Moreno, Nicolas

    2015-10-27

    We study binary blends of asymmetric diblock copolymers (AB/AC) in selective solvents with a mesoscale model. We investigate the morphological transitions induced by the concentration of the AC block copolymer and the difference in molecular weight between the AB and AC copolymers, when segments B and C exhibit hydrogen-bonding interactions. To the best of our knowledge, this is the first work modeling mixtures of block copolymers with large differences in molecular weight. The coassembly mechanism localizes the AC molecules at the interface of A and B domains and induces the swelling of the B-rich domains. The coil size of the large molecular weight block copolymer depends only on the concentration of the short block copolymer (AC or AB), regardless of the B–C interactions. However, the B–C interactions control the morphological transitions that occur in these blends.

  13. Molecular Dynamics Modelling of Block-Copolymer Electrolytes with High t+ Values

    International Nuclear Information System (INIS)

    Molecular Dynamics simulations of the BAB type triblock copolymer lithium poly[(4-styrenesulfonyl) (trifluoromethylenesulfonyl) imide)]-block-poly(ethylene oxide)-block-lithium poly[(4-stryrenesylfonyl) (trifluoromethanesulfonyl) imide] (P(STFSILi)-b-PEO-b-P(STFSILi)) were carried out for different simulation temperatures and B-block lengths. By covalently binding the anion to the polymer backbone, it is immobilised and the cation transference number thereby raised significantly. It was found that the Li-ion diffusion decreases exponentially with growth of the B-block length. The poly(ethylene oxide) matrix dissolves Li-ions already during the equilibration stage of the simulation, and no Li-ion diffusion pathways were identified along the STFSI branches, which significantly influence the transport properties of the material

  14. PRECISE SYNTHESIS OF OLEFIN BLOCK COPOLYMERS USING A SYNDIOSPECIFIC LIVING POLYMERIZATION SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Zheng-guo Cai; Hai-hui Su; Takeshi Shiono

    2013-01-01

    This feature article summarizes the synthesis of novel olefin block copolymers using fast syndiospecific living homo-and copolymerization of propylene,higher 1-alkene,and norbomene with ansa-fluorenylamidodimethyltitaniumbased catalyst according to the authors' recent results.The catalytic synthesis of monodisperse polyolefin and olefin block copolymer was also described using this living system.

  15. Light scattering from block copolymer melts near the order-disorder transition

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Lodge, T. P.; Bates, F. S.

    1994-01-01

    Roč. 2, - (1994), s. 110. ISSN 0009-2347. [Symposium Block Copolymer Dynamics, Chain Dynamics of Block Copolymers: Dynamics near the Ordering Transition. San Diego, 13.03.1994-18.03.1994] R&D Projects: GA AV ČR IA45023 Impact factor: 0.331, year: 1994

  16. Polarizability of DNA Block Copolymer Nanoparticles Observed by Electrostatic Force Microscopy

    NARCIS (Netherlands)

    Sowwan, Mukhles; Faroun, Maryam; Mentovich, Elad; Ibrahim, Imad; Haboush, Shayma; Alemdaroglu, Fikri Emrah; Kwak, Minseok; Richter, Shachar; Herrmann, Andreas

    2010-01-01

    In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single-stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that

  17. Block copolymer self-assembly : homopolymer additives and multiple length scales

    NARCIS (Netherlands)

    Klymko, Tetyana Romanivna

    2008-01-01

    This thesis is devoted to a theoretical study of self-assembly in specific block-copolymer systems. The ability of block copolymer-based systems to organize at the nanoscale level depends on several parameters, such as volume fraction of the different components, their molar masses and the strength

  18. Dilute gels with exceptional rigidity from self-assembling silk-collagen-like block copolymers

    NARCIS (Netherlands)

    Martens, A.A.; Gucht, van der J.; Eggink, G.; Wolf, de F.A.; Cohen Stuart, M.A.

    2009-01-01

    Rheological data on monodisperse block copolymer hydrogels are rare because the amounts produced with various methods usually are not sufficient for materials testing. By biotechnological means, expression of a block copolymer encoding gene in the yeast Pichia pastoris, we produced enough protein bl

  19. Mechanical properties of weakly segregated block copolymers : 1. Synergism on tensile properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers

    NARCIS (Netherlands)

    Weidisch, R.; Michler, G.H.; Fischer, H.; Arnold, M.; Hofmann, S.; Stamm, M.

    1999-01-01

    Mechanical properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers, PS-b-PBMA, with different lengths of the polystyrene block were investigated. The copolymers display a composition range where the tensile strength of the block copolymers exceeds the values of the corresponding homopol

  20. Understanding the ordering mechanisms of self-assembled nanostructures of block copolymers during zone annealing.

    Science.gov (United States)

    Cong, Zhinan; Zhang, Liangshun; Wang, Liquan; Lin, Jiaping

    2016-03-21

    A theoretical method based on dynamic version of self-consistent field theory is extended to investigate directed self-assembly behaviors of block copolymers subjected to zone annealing. The ordering mechanisms and orientation modulation of microphase-separated nanostructures of block copolymers are discussed in terms of sweep velocity, wall preference, and Flory-Huggins interaction parameter. The simulated results demonstrate that the long-range ordered nanopatterns are achieved by lowering the sweep velocity of zone annealing due to the incorporation of templated ordering of block copolymers. The surface enrichment by one of the two polymer species induces the orientation modulation of defect-free nanostructures through finely tuning the composition of block copolymers and the preference of walls. Additionally, the Flory-Huggins interaction parameters of block copolymers in the distinct regions are main factors to design the zone annealing process for creating the highly ordered nanostructures with single orientation. PMID:27004895

  1. Phase behavior of multi-arm star-shaped polystyrene-block-poly(methyl methacrylate) copolymer

    Science.gov (United States)

    Jang, Sangshin; Moon, Hong Chul; Bae, Dusik; Kwak, Jonghen; Kim, Jin Kon

    2013-03-01

    We synthesized star-shaped polystyrene-block-poly(methyl methacrylate) copolymer (PS- b-PMMA) by utilizing α-cyclodextrin (α-CD) as a core of the star-shaped block copolymer. Eighteen hydroxyl groups on α-CD were transformed to bromine by the reaction with α-bromoisobutyryl bromide. We found that the number of bromine substituted arms per one α-CD was higher than 16, which was determined by nuclear magnetic resonance and Matrix-assisted laser desorption/ionization. We could control molecular weight of block copolymers by changing polymerization times. The block copolymers were characterized by gel permeation chromatography and nuclear magnetic resonance. Phase behaviors of these star-shaped block copolymers were investigated by small angle X-ray scattering and transmission electron microscopy.

  2. Understanding the ordering mechanisms of self-assembled nanostructures of block copolymers during zone annealing

    Science.gov (United States)

    Cong, Zhinan; Zhang, Liangshun; Wang, Liquan; Lin, Jiaping

    2016-03-01

    A theoretical method based on dynamic version of self-consistent field theory is extended to investigate directed self-assembly behaviors of block copolymers subjected to zone annealing. The ordering mechanisms and orientation modulation of microphase-separated nanostructures of block copolymers are discussed in terms of sweep velocity, wall preference, and Flory-Huggins interaction parameter. The simulated results demonstrate that the long-range ordered nanopatterns are achieved by lowering the sweep velocity of zone annealing due to the incorporation of templated ordering of block copolymers. The surface enrichment by one of the two polymer species induces the orientation modulation of defect-free nanostructures through finely tuning the composition of block copolymers and the preference of walls. Additionally, the Flory-Huggins interaction parameters of block copolymers in the distinct regions are main factors to design the zone annealing process for creating the highly ordered nanostructures with single orientation.

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

    Science.gov (United States)

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

    2014-01-01

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

  4. Ultrathin and Micellar Block Copolymer Films for Nanopatterning

    Science.gov (United States)

    Möller, Martin

    1998-03-01

    The formation of A-B functionalized surfaces, where nanometer sized A and B patches are distinguished for their different physical and chemical properties, represent a rather virgin field of research. We will present a technology for generating nanosized chemical heterogeneous surfaces by combination of self-organization of metal particle containing diblock copolymer micelles and conventional semiconductor etching techniques. Polystrene-block-poly(2-vinylpyridine) diblock copolymers form reverse micelles in toluene, i.e., a core of P2VP is protected by a shell of PS. Such nanocompartments are used for generating metal or semiconductor particles of equal size in each single micelle in solution. The micelle stabilized particles can be cast to mono micellar films, forming quasi hexagonal arranged lattices. The particle to particle distance (10 to 200nm) is controlled by the polymer shell and the particles size (1 to 20nm) by the micellar compartment. After film formation the polymer shell can be removed comp letely by using an oxygen plasma technique resulting in the deposition of the naked clusters on different substrates without destroying the former particle organization. These highly regular metal or semiconducting nanopatches can cover macroscopic areas (5cm x 5cm). The metal patterns are used for binding single makromolecules or as masks for nanolithography. Epitaxially grown semiconductors like GaAs, InGaAs or InP have been structured by islands or holes and their quantisized band structure has been in vestigated.

  5. Novel fluorescent amphiphilic block copolymers: photophysics behavior and interactions with DNA

    Directory of Open Access Journals (Sweden)

    2007-06-01

    Full Text Available In this study, novel amphiphilic fluorescent copolymers poly(N-vinylpyrrolidone-b-poly(N-methacryloyl-N'-(α-naphthylthiourea (PVP-b-PNT were synthesized via ATRP with poly(N-vinylpyrrolidone-Cl as macroinitiator and N-methacryloyl-N'-α-naphthylthiourea (NT as hydrophobic segment. PVP-b-PNT copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The aggregation behavior of PVP-b-PNT in water was investigated by transmission electron microscope (TEM and dynamic light scattering (DLS measurement. The photophysics behavior of PVP-b-PNT showed that block copolymer formed strong excimer. The interaction of DNA with the block copolymer made the excimer of block copolymer quench. The cytotoxicity result of PVP-b-PNT in cell culture in vitro indicated that this copolymer PVP-b-PNT had good biocompatibility.

  6. Synthesis and gas permeability of block copolymers composed of poly(styrene-co-acrylonitrile) and polystyrene blocks

    Czech Academy of Sciences Publication Activity Database

    Lokaj, Jan; Brožová, Libuše; Holler, Petr; Pientka, Zbyněk

    2002-01-01

    Roč. 67, č. 2 (2002), s. 267-278. ISSN 0010-0765 R&D Projects: GA ČR GA203/99/0572 Institutional research plan: CEZ:AV0Z4050913 Keywords : azeotropic styrene- acrylonitrile copolymers * block copolymers * nitroxide-mediated copolymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.848, year: 2002

  7. Correlative infrared nanospectroscopic and nanomechanical imaging of block copolymer microdomains.

    Science.gov (United States)

    Pollard, Benjamin; Raschke, Markus B

    2016-01-01

    Intermolecular interactions and nanoscale phase separation govern the properties of many molecular soft-matter systems. Here, we combine infrared vibrational scattering scanning near-field optical microscopy (IR s-SNOM) with force-distance spectroscopy for simultaneous characterization of both nanoscale optical and nanomechanical molecular properties through hybrid imaging. The resulting multichannel images and correlative analysis of chemical composition, spectral IR line shape, modulus, adhesion, deformation, and dissipation acquired for a thin film of a nanophase separated block copolymer (PS-b-PMMA) reveal complex structural variations, in particular at domain interfaces, not resolved in any individual signal channel alone. These variations suggest that regions of multicomponent chemical composition, such as the interfacial mixing regions between microdomains, are correlated with high spatial heterogeneity in nanoscale material properties. PMID:27335750

  8. Microstructural organization of polydimethylsiloxane based polyurethane block copolymers

    Science.gov (United States)

    Hernandez, Rebeca; Weksler, Jadwiga; Padsalgikar, Ajay; Runt, James

    2007-03-01

    Microphase separation was investigated for polyurethane block copolymers synthesized from MDI and 1,4 butanediol as the hard segments, and poly(hexamethyleneoxide) (MW ˜ 700) and bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane) as soft segments (MW ˜ 1000). The neat PDMS-based diol presents two segmental relaxations corresponding to the principle siloxane repeat unit and to the hydroxyethoxypropyl end group segments, respectively. When incorporated in the polyurethane, the siloxane units form a phase without intermixing with hard segments and the polyether end group segments are mixed with the second macrodiol and some short hard segment sequences. The microdomain morphology was characterized by atomic force microscopy and small-angle X-ray scattering, and the scattering data were analyzed using an approach based on a modified core-shell model. The model includes core hard segment particles (MDI-BDO), surrounded by a mixed polyether shell (PHMO and hydroxyethoxypropyl end group segments), and a matrix composed of the siloxane units.

  9. Ultraporous films with uniform nanochannels by block copolymer micelles assembly

    KAUST Repository

    Nunes, Suzana Pereira

    2010-10-12

    Films with high pore density and regularity that are easy to manufacture by conventional large-scale technology are key components aimed for fabrication of new generations of magnetic arrays for storage media, medical scaffolds, and artificial membranes. However, potential manufacture strategies like the self-assembly of block copolymers, which lead to amazing regular patterns, could be hardly reproduced up to now using commercially feasible methods. Here we report a unique production method of nanoporous films based on the self-assembly of copper(II) ion-polystyrene-b-poly(4-vinylpyridine) complexes and nonsolvent induced phase separation. Extremely high pore densities and uniformity were achieved. Water fluxes of 890 L m-2 h-1 bar-1 were obtained, which are at least 1 order of magnitude higher than those of commercially available membranes with comparable pore size. The pores are also stimuli (pH)-responsive. © 2010 American Chemical Society.

  10. Fluorinated polyphenylenevinylene (PPV) block co-polymers for nanophotonics

    Science.gov (United States)

    Sun, Sam-Shajing; Nguyen, Thuong; Brooks, Jaleesa

    2013-09-01

    Polymer based optoelectronic materials and thin film devices exhibit great potential in future space applications due to their flexibility, light weight, large light absorption coefficient, and promising radiation tolerance in space environment as compared to their inorganic semiconductor counterparts. Since carbon-fluorine (C-F) chemical bonds are much stronger than the carbon-hydrogen (C-H) bonds, fluorinated polymer films offer great potential for space applications due their expected resistance to oxidation, thermal stability, excellent wear properties, and low coefficients of friction. Their use in a space environment is extremely attractive since they are expected to retain their lubricating characteristics in vacuum, unlike many solid lubricants. Current existing polymer photovoltaic materials and devices suffer low photoelectric power conversion efficiencies due to a number factors including poor morphologies at nano scale that hinder the charge separation and transport. This paper reports our recent work on a fluorinated DBfA type block copolymer system where the donor (D) block contains a donor substituted and hydrocarbon based polyphenylenevinylene (PPV), acceptor (fA) block contains a fluorinated and a sulfone acceptor substituted polyphenylenevinylene (f-PPV), and B is a non-conjugated and flexible bridge unit. Preliminary studies reveal DBfA exhibits better nano phase morphologies and over 100 times more efficient optoelectronic conversion efficiencies as compared to D/fA blend.

  11. Effects of stiffness and polydispersity on the phase behaviour of block copolymers

    OpenAIRE

    Jager, Pieter Menno

    2006-01-01

    In this thesis the phase behaviour of melts of chain-like molecules, also known as polymers, is studied. Polymers are built from monomers. These monomers are connected consecutively to form chains. If all monomers are of the same kind the chain is called a homopolymer. The polymers studied in this thesis are block copolymers. In a block copolymer different kinds of homopolymers or so-called blocks are connected. For example a diblock copolymer consists of two different kinds of blocks A and B...

  12. Using click chemistry to modify block copolymers and their morphologies

    Science.gov (United States)

    Wollbold, Johannes

    Microphase separated block copolymers (BCPs) are emerging as promising templates and scaffolds for the fabrication of nanostructured materials. To achieve the desired nanostructures, it is necessary to establish convenient approaches to control the morphology of BCPs. It remains challenging to induce morphological transitions of BCPs via external fields. Click chemistry, especially alkyne/azide click chemistry, has been widely used to synthesize novel functionalized materials. Here, we demonstrate that alkyne/azide click chemistry can be used as an efficient approach to chemically modify BCPs and therefore induce morphological transitions. Alkyne-functionalized diblock copolymers (di-BCPs) poly(ethylene oxide)- block-poly(n-butyl methacrylate-random-propargyl methacrylate) (PEO-b-P(nBMA-r-PgMA)) have been successfully synthesized. When the di-BCP is blended with an azide additive Rhodamine B azide and annealed at elevated temperatures, click reaction occurs between the two components. With the Rhodamine B structure attached to the polymer backbone, the di-BCP shows dramatic change in the interactions between the two blocks and the volume fraction of each block. As a result, morphological transitions, such as disorder-to-order transitions (DOTs) and order-to-order transitions (OOTs), are observed. The reaction kinetics and morphology evolution during the click chemistry induced DOTs have been investigated by in-situ and ex-situ characterizations, and fast kinetics properties are observed. Microphase separated morphologies after the DOTs or OOTs are dictated by the composition of neat di-BCPs and the mole ratio between the alkyne and azide groups. The DOTs of PEO-b-P(nBMA-r-PgMA) di-BCPs induced by alkyne/azide click chemistry have also been achieved in thin film geometries, with comparable kinetics to bulk samples. The orientation of the microdomains is dependent on the grafting density of Rhodamine B structure as well as film thickness. At higher grafting densities

  13. Anti-Biofouling Properties of Comblike Block Copolymers with Amphiphilic Side Chains

    International Nuclear Information System (INIS)

    Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed

  14. PHASE STRUCTURE AND THERMAL BEHAVIOR OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144~146℃. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.

  15. Amine-containing block copolymers: long-term adhesion promoters and corrosion resistant coatings

    Energy Technology Data Exchange (ETDEWEB)

    Small, J.H.; Saunders, R.S.; Kent, M.S.

    1996-07-01

    Arylamine-containing diblock copolymers were prepared via ring- opening metathesis polymerization (ROMP) to afford well-defined phase- separated materials. Alteration of the functionaity in a block, as well as the size of the blocks, allowed for the synthesis of self- assembled monolayers on a copper surface. The arylamine-containing block exhibited a strong binding affinity for the copper surface as seen by neutron reflectivity experiments. In addition, neutron reflectivity data verifies the self-assembly of block copolymer monolayers normal to the copper surface. Block copolymers prepared in this manner allow for the preparation of a wide range of adhesives and corrosion resistant materials. The use of ring-opening metathesis polymerization is important because it permits the synthesis of a variety of functionalized block copolymers.

  16. Laser processing of polyethylene glycol derivative and block copolymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cristescu, R. [National Institute for Laser, Plasma and Radiation Physics, MG-36, RO-77125, Bucharest (Romania)], E-mail: rodica.cristescu@inflpr.ro; Popescu, C.; Popescu, A.C.; Grigorescu, S.; Duta, L.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, MG-36, RO-77125, Bucharest (Romania); Andronie, A.; Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, P.O. Box MG-11, Bucharest-Magurele (Romania); Ionescu, O.S.; Mihaiescu, D. [University of Agriculture Sciences and Veterinary Medicine, 59 Marasti, Bucharest (Romania); Buruiana, T. [Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, 41A, Iasi (Romania); Chrisey, D.B. [Rensselaer Polytechnic Institute, Department of Material Science, 110 8th Street, Troy, NY 12180-3590 (United States)

    2009-03-01

    We report the deposition by MAPLE of: (i) a novel polyethylene glycol derivative with carboxyl functional groups and (ii) a block copolymer: poly(ethylene glycol)methyl ether-block-poly(caprolactone)-block-poly(ethylene glycol)methyl ether. We used a KrF* excimer laser source ({lambda} = 248 nm, {tau} = 25 ns, {nu} = 5 Hz). The laser fluence was set within the 200-700 mJ/cm{sup 2} range. The deposited thin films have been investigated by FTIR and AFM. We have concluded that the main functional groups of starting materials are present in the transferred film. We also examined the influence of laser fluence on both thin film structure and morphology.

  17. Laser processing of polyethylene glycol derivative and block copolymer thin films

    International Nuclear Information System (INIS)

    We report the deposition by MAPLE of: (i) a novel polyethylene glycol derivative with carboxyl functional groups and (ii) a block copolymer: poly(ethylene glycol)methyl ether-block-poly(caprolactone)-block-poly(ethylene glycol)methyl ether. We used a KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 5 Hz). The laser fluence was set within the 200-700 mJ/cm2 range. The deposited thin films have been investigated by FTIR and AFM. We have concluded that the main functional groups of starting materials are present in the transferred film. We also examined the influence of laser fluence on both thin film structure and morphology

  18. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    International Nuclear Information System (INIS)

    Highlights: • QAS-containing fluorosilicone multi-block copolymers were synthesized. • The block length of PHFBMA in the copolymers was tailored via RAFT polymerization. • Surface roughness of the copolymers decreased with the increased PHFBMA content. • A certain length of PHFBMA block enhanced C−N+ percentage on the surface. - Abstract: Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition–fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N+ composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N+ content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings

  19. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Fang; Qin, Xiaoshuai; Li, Yancai; Ren, Lixia; Zhao, Yunhui, E-mail: zhaoyunhui@tju.edu.cn; Yuan, Xiaoyan

    2015-08-30

    Highlights: • QAS-containing fluorosilicone multi-block copolymers were synthesized. • The block length of PHFBMA in the copolymers was tailored via RAFT polymerization. • Surface roughness of the copolymers decreased with the increased PHFBMA content. • A certain length of PHFBMA block enhanced C−N{sup +} percentage on the surface. - Abstract: Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition–fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N{sup +} composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N{sup +} content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings.

  20. Investigating self-assembly and metal nanoclusters in aqueous di-block copolymers solutions

    CERN Document Server

    Lo Celso, F; Triolo, R; Triolo, A; Strunz, P; Bronstein, L; Zwanziger, J; Lin, J S

    2002-01-01

    Self-assembling properties of di-block copolymers/ surfactant hybrids in aqueous solution can be exploited to obtain metal nanoparticles stable dispersion. Results will be presented here for polystyrene-block-poly(ethylene oxide) solutions. A SANS structural investigation has been performed over different molecular weights of both hydrophilic and hydrophobic block, by varying temperature and concentration of the copolymer. A SAXS characterization of micellar systems containing Pt nanoparticles is reported. (orig.)

  1. How to Place Block Copolymer Molecules at the Interface of a Binary Blend

    Science.gov (United States)

    Chen, Zhong-Ren; Xu, Yuci; Zhong, Shuo

    2015-03-01

    Block copolymers have been used to reduce the domain size of immiscible polymer blends and thus improve the mechanical and other properties. The effectiveness of this method, however, depends on the percentage of these polymeric surfactants residing at the interface of the blend. In fact, theoretical as well as experimental work indicate that a large percentage of block copolymers form micelles in the bulk of one or both of the component polymers. These micelles may serve as weak spots initiating crack propagation. Previous work have been focused on the design of molecular architecture and synthesis of new block copolymers to address this problem. In this presentation, a simple mixing strategy is applied to make each block copolymer molecule stay at the interface. As one example, when this strategy is used to mix natural rubber (NR) with butadiene rubber (BR), a small amount of low molecular weight block copolymer (LIR) improves both processing characteristics such as melt viscosity and mechanical properties of cured samples, such as crack resistance. AFM micrographs show the much smaller domain size; and an original real-time monitoring system reveals the lowest crack growth rate. Using a model A/B/A-B binary blend, we have witnessed by microscopy that all block copolymer molecules form micelles at the first mixing step, and all of these micelles are disappeared and all block copolymer molecules stay at the interface after the second mixing step.

  2. Fabrication of Bioactive Surfaces by Functionalization of Electroactive and Surface-Active Block Copolymers

    Directory of Open Access Journals (Sweden)

    Omotunde Olubi

    2014-08-01

    Full Text Available Biofunctional block copolymers are becoming increasingly attractive materials as active components in biosensors and other nanoscale electronic devices. We have described two different classes of block copolymers with biofuctional properties. Biofunctionality for block copolymers is achieved through functionalization with appropriate biospecific ligands. We have synthesized block copolymers of electroactive poly(3-decylthiophene and 2-hydroxyethyl methacrylate by atom transfer radical polymerization. The block copolymers were functionalized with the dinitrophenyl (DNP groups, which are capable of binding to Immunoglobulin E (IgE on cell surfaces. The block copolymers were shown to be redox active. Additionally, the triblock copolymer of α, ω-bi-biotin (poly(ethylene oxide-b-poly (styrene-b-poly(ethylene oxide was also synthesized to study their capacity to bind fluorescently tagged avidin. The surface-active property of the poly(ethylene oxide block improved the availability of the biotin functional groups on the polymer surfaces. Fluorescence microscopy observations confirm the specific binding of biotin with avidin.

  3. Surface Modification of Block Copolymer Through Sulfur Containing Plasma Treatment.

    Science.gov (United States)

    Choi, Sang Wook; Shin, Jae Hee; Jeon, Min Hwan; Mun, Jeong Ho; Kim, Sang Ouk; Yeom, Geun Young; Kim, Kyong Nam

    2015-10-01

    Some of the important issues of block copolymer (BCP) as an application to the potential low cost next generation lithography are thermal stability and deformation during pattern transfer process in addition to defect density, line edge/width roughness, etc. In this study, sulfur containing plasma treatment was used to modify the BCP and the effects of the plasma on the properties of plasma treated BCP were investigated. The polystyrene hole pattern obtained from polystyrene polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) was initially degraded when the polystyrene hole was annealed at 190 °C for 15 min. However, when the hole pattern was treated using sulfur containing plasmas using H2S or SF6 up to 2 min, possibly due to the sulfurization of the polystyrene hole surface, no change in the hole pattern was observed after the annealing even though there is a slight change in hole shapes during the plasma treatment. The optimized plasma treated polystyrene pattern showed the superior characteristics as the mask layer by showing better thermal stability, higher chemical inertness, and higher etch selectivity during plasma etching. PMID:26726468

  4. Bicontinuous ceramics with high surface area from block copolymer templates.

    Science.gov (United States)

    Hsueh, Han-Yu; Ho, Rong-Ming

    2012-06-01

    Mesoporous polymers with gyroid nanochannels can be fabricated from the self-assembly of degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by hydrolysis of PLLA block. Well-defined polymer/ceramic nanohybrid materials with inorganic gyroid nanostructures in a PS matrix can be obtained by using the mesoporous PS as a template for sol-gel reaction. Titanium tetraisopropoxide (TTIP) is used as a precursor to give a model system for the fabrication of metal oxide nanostructures from reactive transition metal alkoxides. By controlling the rates of capillary-driven pore filling and sol-gel reaction, the templated synthesis can be well-developed. Also, by taking advantage of calcination, bicontinuous TiO(2) with controlled crystalline phase (i.e., anatase phase) can be fabricated after removal of the PS template and crystallization of TiO(2) by calcination leading to high photocatalytic efficiency. This new approach provides an easy way to fabricate high-surface-area and high-porosity ceramics with self-supporting structure and controlled crystalline phase for practical applications. As a result, a platform technology to fabricate precisely controlled polymer/ceramic nanohybrids and mesoporous ceramic materials can be established. PMID:22530553

  5. Flexible Battery Cathodes Enabled by Conductive Block Copolymers

    Science.gov (United States)

    Lutkenhaus, Jodie; Verduzco, Rafael; An, Hyosung; Lin, Yen-Hao; Lutkenhaus Laboratory Collaboration; Verduzco Laboratory Collaboration

    2015-03-01

    Alone, or as part of hybrid electrodes, conductive polymers are poised to play an integral role in the new and growing field of flexible or ``plastic'' power. Here we demonstrate that even small amounts of a poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) block copolymer, acting as an ion and electron conductor, can bring about significant improvements in energy storage and mechanical flexibility for V2O5 hybrid cathodes for Li-ion batteries. By following this approach, traditional inert polymer binders and carbon black additives are not needed. V2O5 alone has a high theoretical capacity that is limited in practical application by low conductivity. Further, V2O5 alone is brittle and breaks upon repeated flexure. P3HT-b-PEO serves to address both these issues. This presentation will cover how these hybrid electrodes are formed and the resulting physicochemical properties that lead to its enhanced flexibility and energy storage.

  6. Controlling sub-microdomain structure in microphase-ordered block copolymers and their nanocomposites

    Science.gov (United States)

    Bowman, Michelle Kathleen

    Block copolymers exhibit a wealth of morphologies that continue to find ubiquitous use in a diverse variety of mature and emergent (nano)technologies, such as photonic crystals, integrated circuits, pharmaceutical encapsulents, fuel cells and separation membranes. While numerous studies have explored the effects of molecular confinement on such copolymers, relatively few have examined the sub-microdomain structure that develops upon modification of copolymer molecular architecture or physical incorporation of nanoscale objects. This work will address two relevant topics in this vein: (i) bidisperse brushes formed by single block copolymer molecules and (ii) copolymer nanocomposites formed by addition of molecular or nanoscale additives. In the first case, an isomorphic series of asymmetric poly(styrene-b -isoprene-b-styrene) (S1IS2) triblock copolymers of systematically varied chain length has been synthesized from a parent SI diblock copolymer. Small-angle x-ray scattering, coupled with dynamic rheology and self-consistent field theory (SCFT), reveals that the progressively grown S2 block initially resides in the I-rich matrix and effectively reduces the copolymer incompatibility until a critical length is reached. At this length, the S2 block co-locates with the S1 block so that the two blocks generate a bidisperse brush (insofar as the S1 and S2 lengths differ). This single-molecule analog to binary block copolymer blends affords unique opportunities for materials design at sub-microdomain length scales and provides insight into the transition from diblock to triblock copolymer (and thermoplastic elastomeric nature). In the second case, I explore the distribution of molecular and nanoscale additives in microphase-ordered block copolymers and demonstrate via SCFT that an interfacial excess, which depends strongly on additive concentration, selectivity and relative size, develops. These predictions are in agreement with experimental findings. Moreover, using a

  7. Phase behavior of miscible block copolymer blends and baraplastic property

    International Nuclear Information System (INIS)

    The phase behavior of the multi-component polymer systems such as blends and block copolymers (BCPs) has been studied extensively, as it determines the chemical and physical properties of the polymeric materials in practical applications. Above all, polymer baroplasticity is a desirable property for the recycling and regenerating industries, since it allows the polymers to flow at relatively mild pressure. Particularly, the compressibility issue on the enhanced miscibility with pressure has been an attractive topic, because an ordered state of the baroplastic BCPs becomes a phase-mixed state (or disordered phase) between the two dissimilar blocks upon pressurizing. This is in contrast to the incompressibility that was dictated by the enthalpic effect arising from the increased unfavorable contacts between the two blocks by increasing pressure. The phase behaviors of BCP blends composed of the weakly interacting (with no specific interaction) polystyrene-b-poly(n-butyl methacrylate) (PS-b-PnBMA) and deuterated polystyreneb- poly-(n-hexyl methacrylate) (dPS-b-PnHMA) were investigated by Small-Angle Neutron Scattering(SANS) and Depolarized Light Scattering (DPLS) measurements. Interestingly, pressure dependence of various phase transitions for the miscible BCP blends was significantly changed, in which the blends consist of a PS-b-PnBMA and a deuterated dPS-b-PnHMA. To elucidate the origin and difference in baroplasticity of weakly interacting BCP blends, the pressure dependence of transition temperatures was evaluated using enthalpic and volumetric changes at phase transitions. We also demonstrate that the entropic compressibility for the miscible BCP blends is a baroplastic indicator, which was characterized by the negative volume change on mixing (ΔVmix) at transitions.

  8. Directed self-assembly of block copolymer films on atomically-thin graphene chemical patterns.

    Science.gov (United States)

    Chang, Tzu-Hsuan; Xiong, Shisheng; Jacobberger, Robert M; Mikael, Solomon; Suh, Hyo Seon; Liu, Chi-Chun; Geng, Dalong; Wang, Xudong; Arnold, Michael S; Ma, Zhenqiang; Nealey, Paul F

    2016-01-01

    Directed self-assembly of block copolymers is a scalable method to fabricate well-ordered patterns over the wafer scale with feature sizes below the resolution of conventional lithography. Typically, lithographically-defined prepatterns with varying chemical contrast are used to rationally guide the assembly of block copolymers. The directed self-assembly to obtain accurate registration and alignment is largely influenced by the assembly kinetics. Furthermore, a considerably broad processing window is favored for industrial manufacturing. Using an atomically-thin layer of graphene on germanium, after two simple processing steps, we create a novel chemical pattern to direct the assembly of polystyrene-block-poly(methyl methacrylate). Faster assembly kinetics are observed on graphene/germanium chemical patterns than on conventional chemical patterns based on polymer mats and brushes. This new chemical pattern allows for assembly on a wide range of guiding periods and along designed 90° bending structures. We also achieve density multiplication by a factor of 10, greatly enhancing the pattern resolution. The rapid assembly kinetics, minimal topography, and broad processing window demonstrate the advantages of inorganic chemical patterns composed of hard surfaces. PMID:27528258

  9. Self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acid

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Černochová, Zulfiya; Borisova, O.; Billon, L.; Borisov, O.

    Český Krumlov, 2015. s. 34. [Discussion workshop on ( bio )Macromolecular Ionic Systems. 10.05.2015-14.05.2015, Český Krumlov] R&D Projects: GA MŠk(CZ) LH14079 Institutional support: RVO:61389013 Keywords : block copolymers * gradient copolymers * light scattering Subject RIV: CD - Macromolecular Chemistry

  10. Synthesis nad properties of amphiphilic block copolymers containing poly 5-vinyltetrazoline or methyl-4-vinylpyridinium iodide

    Czech Academy of Sciences Publication Activity Database

    Gromadzki, D.; Janata, Miroslav; Lokaj, Jan; Štěpánek, Petr

    Arcachon: European Science Foundation Collaborative Research, 2005. P2. [Self-Assembled Structures of Amphiphilic Ionic Copolymers in Solutions and Interfaces. 11.5.2005-14.5.2005, Arcachon] Institutional research plan: CEZ:AV0Z40500505 Keywords : amphiphilic block copolymers Subject RIV: CD - Macromolecular Chemistry

  11. Novel fluorinated block copolymer architectures fuelled by atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Jankova, Katja; Hvilsted, Søren

    2005-01-01

    Block copolymers based on poly(pentafluorostyrene), PFS, in various numbers and of different lengths, and polystyrene are prepared by atom transfer radical polymerization (ATRP). Di- and triblock copolymers with varying amounts of PFS were synthesized employing either I phenylethylbromide or 1,4-...

  12. Synthesis and Characterization of Stimuli Responsive Block Copolymers, Self-Assembly Behavior and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Michael Duane Determan

    2005-12-17

    The central theme of this thesis work is to develop new block copolymer materials for biomedical applications. While there are many reports of stimuli-responsive amphiphilic [19-21] and crosslinked hydrogel materials [22], the development of an in situ gel forming, pH responsive pentablock copolymer is a novel contribution to the field, Figure 1.1 is a sketch of an ABCBA pentablock copolymer. The A blocks are cationic tertiary amine methacrylates blocked to a central Pluronic F127 triblock copolymer. In addition to the prerequisite synthetic and macromolecular characterization of these new materials, the self-assembled supramolecular structures formed by the pentablock were experimentally evaluated. This synthesis and characterization process serves to elucidate the important structure property relationships of these novel materials, The pH and temperature responsive behavior of the pentablock copolymer were explored especially with consideration towards injectable drug delivery applications. Future synthesis work will focus on enhancing and tuning the cell specific targeting of DNA/pentablock copolymer polyplexes. The specific goals of this research are: (1) Develop a synthetic route for gel forming pentablock block copolymers with pH and temperature sensitive properties. Synthesis of these novel copolymers is accomplished with ATRP, yielding low polydispersity and control of the block copolymer architecture. Well defined macromolecular characteristics are required to tailor the phase behavior of these materials. (2) Characterize relationship between the size and shape of pentablock copolymer micelles and gel structure and the pH and temperature of the copolymer solutions with SAXS, SANS and CryoTEM. (3) Evaluate the temperature and pH induced phase separation and macroscopic self-assembly phenomenon of the pentablock copolymer. (4) Utilize the knowledge gained from first three goals to design and formulate drug delivery formulations based on the multi

  13. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    Science.gov (United States)

    Zhou, Fang; Qin, Xiaoshuai; Li, Yancai; Ren, Lixia; Zhao, Yunhui; Yuan, Xiaoyan

    2015-08-01

    Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition-fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N+ composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N+ content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings.

  14. Phase Behavior of Star-shaped polystyrene-block-poly(methyl methacrylate) Copolymers

    Science.gov (United States)

    Jang, Sangshin; Moon, Hongchul; Lee, Youngmin; Kim, Jin Kon

    2012-02-01

    Star-shaped polystyrene-block-poly(methyl methacrylate) copolymer (PS-b-PMMA) was synthesized by utilizing α-cyclodextrin (α-CD) as a junction point of the star-shaped block copolymer. Eighteen hydroxyl groups on α-CD were substituted with bromine by the reaction with α-bromoisobutyryl bromide for atom transfer radical polymerization. We found that the number of bromine substituted arms per one α-CD was higher than 16 measured by nuclear magnetic resonance and Matrix-assisted laser desorption/ionization. We could control molecular weight of this unusual kind of block copolymer depending on polymerization times. Those polymers were characterized by gel permeation chromatography and nuclear magnetic resonance. Phase behavior of these star-shaped block copolymers were investigated.

  15. Complexation-tailored morphology of asymmetric block copolymer membranes

    KAUST Repository

    Madhavan, Poornima

    2013-08-14

    Hydrogen-bond formation between polystyrene-b-poly (4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) and -OH/-COOH functionalized organic molecules was used to tune morphology of asymmetric nanoporous membranes prepared by simultaneous self-assembly and nonsolvent induced phase separation. The morphologies were characterized by field emmision scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Hydrogen bonds were confirmed by infrared (IR), and the results were correlated to rheology characterization. The OH-functionalized organic molecules direct the morphology into hexagonal order. COOH-functionalized molecules led to both lamellar and hexagonal structures. Micelle formation in solutions and their sizes were determined using dynamic light scattering (DLS) measurements and water fluxes of 600-3200 L/m 2·h·bar were obtained. The pore size of the plain BCP membrane was smaller than with additives. The following series of additives led to pores with hexagonal order with increasing pore size: terephthalic acid (COOH-bifunctionalized) < rutin (OH-multifunctionalized) < 9-anthracenemethanol (OH-monofunctionalized) < 3,5-dihydroxybenzyl alcohol (OH-trifunctionalized). © 2013 American Chemical Society.

  16. Silicon crystallization in nanodot arrays organized by block copolymer lithography

    Energy Technology Data Exchange (ETDEWEB)

    Perego, Michele, E-mail: michele.perego@mdm.imm.cnr.it; Andreozzi, Andrea; Seguini, Gabriele [IMM-CNR, Laboratorio MDM (Italy); Schamm-Chardon, Sylvie; Castro, Celia; BenAssayag, Gerard [Université de Toulouse, nMat Group, CEMES-CNRS (France)

    2014-12-15

    Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 10{sup 11} cm{sup −2}), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO{sub 2} and high temperature annealing (1050 °C, N{sub 2}), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot.

  17. Defect motion and annihilation in block copolymer thin films

    Science.gov (United States)

    Mueller, Marcus; Li, Weihua

    2015-03-01

    Using self-consistent field theory and computer simulation of a soft, coarse-grained particle model we study defect motion and annihilation in thin films of lamella-forming block copolymers on neutral and chemically patterned substrates. By virtue of the strain-field mediated interactions, dislocation defects with opposite orientation move towards each other. This motion depends both on the thermodynamic, strain-field mediated driving force and the single-chain dynamics that is required to alter the morphology and reduce the distance between the defect cores. This interplay results in a qualitative dependence of the time evolution on the topology of the defect morphology. Upon collision of the defects, they either spontaneously annihilate or form a metastable, tight defect pair. In the latter case, a free-energy barrier has to be overcome to finally produce a defect-free structure. Computing the minimum free-energy path within self-consistent field theory we investigate the dependence of the free-energy barriers of defect motion and annihilation on incompatibility, strength of the chemical surface pattern, and defect morphology. European Union FP7 / GA No. 619793 CoLiSA.MMP.

  18. Direct Immersion Annealing (DIA) of Block Copolymer Thin Film

    Science.gov (United States)

    Modi, Arvind; Karim, Alamgir

    2014-03-01

    Solvent Vapor Annealing (SVA) methodologies of block copolymer (BCP) films have demonstrated excellent potential for control of nanostructures and morphologies. However, SVA designs require sophisticated instrumentation, and fine control of system parameters in batch processing mode which is relatively complex and limits its feasibility. We developed a faster and robust solvent immersion strategy for microphase separation and nanostructure control of as-cast BCP thin films with minimal sophistication. Our Direct Immersion Annealing (DIA) method requires immersion in a mixture of non-solvent and good solvent (for BCP) for annealing. A non-solvent component prevents dissolution of the film resting on substrate while a good solvent percolates through the film, plasticizes it, and shifts glass-transition below room temperature leading to microphase separation and ordering. Our study of PS-PMMA system demonstrates that a robust control over thin film ordering and transient swelling could be achieved through a fine control of solubility parameter of solvent mixture and temperature with no dead-time. Further, we exhibit the utility of DIA for alignment of BCP domains on topographically patterned substrates. University of Akron Research Foundation (UARF).

  19. Silicon crystallization in nanodot arrays organized by block copolymer lithography

    International Nuclear Information System (INIS)

    Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 1011 cm−2), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO2 and high temperature annealing (1050 °C, N2), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot

  20. Host-guest self-assembly in block copolymer blends.

    Science.gov (United States)

    Park, Woon Ik; Kim, Yongjoo; Jeong, Jae Won; Kim, Kyungho; Yoo, Jung-Keun; Hur, Yoon Hyung; Kim, Jong Min; Thomas, Edwin L; Alexander-Katz, Alfredo; Jung, Yeon Sik

    2013-01-01

    Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology. As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated. These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs. PMID:24217036

  1. Solid-supported polymer bilayers formed by coil-coil block copolymers.

    Science.gov (United States)

    Yang, Yan-Ling; Tsao, Heng-Kwong; Sheng, Yu-Jane

    2016-08-14

    The formation and physical properties of solid-supported polymer bilayers (SPBs) on an adhesive substrate have been explored by dissipative particle dynamics simulations. A SPB is developed by the adsorption of vesicles formed by diblock copolymers in a selective solvent. The adsorbed vesicle can remain intact or become ruptured into a SPB, depending on the interaction between solvophobic blocks and solvent and the interaction between solvophilic blocks and the substrate. The morphological phase diagram of adsorbed vesicles is acquired. The influence of polymer adhesion strength and solvophobicity on the geometrical and mechanical properties of a SPB is systematically studied as well. It is found that vesicular disruption is easily triggered for strong adhesion strength. Moreover, for strong adhesion strength and weak solvophobicity, the fluctuation of membrane height is impeded while the area of fluctuation is enhanced. PMID:27418114

  2. Biosynthesis and characterization of diblock copolymer of p(3-hydroxypropionate)-block-p(4-hydroxybutyrate) from recombinant Escherichia coli

    DEFF Research Database (Denmark)

    Tripathi, Lakshmi; Wu, Linping; Meng, Dechuan;

    2013-01-01

    Poly(4-hydroxybutyrate) (P4HB) is a highly elastic polymer, whereas poly(3-hydroxypropionate) (P3HP) is a polymer with enormous tensile strength. This study aimed to biosynthesize a block copolymer consisting of soft P4HB block with a strong P3HP block to gain unique and excellent material...... superior properties over random copolymers P(3HP-co-4HB). The block copolymers had two glass transition temperatures (Tg) and two melting temperatures (Tm). In comparison to the homopolymers P3HP and P4HB, incorporation of block microstructure resulted in the lowering of Tm, block copolymers were revealed...

  3. Enhancing ordering dynamics in solvent-annealed block-copolymer films by lithographic hard masks supports

    OpenAIRE

    Stenbock-Fermor, Anja; Knoll, Armin W.; Böker, Alexander; Tsarkova, Larisa

    2014-01-01

    We studied solvent-driven ordering dynamics of block copolymer films supported by a densely cross-linked polymer network designed as organic hard mask (HM) for lithographic fabrications. The ordering of microphase separated domains at low degrees of swelling corresponding to intermediate/strong segregation regimes was found to proceed significantly faster in films on a HM layer as compared to similar block copolymer films on silicon wafers. The ten-fold enhancement of the chain mobility was e...

  4. Synthesis and Characterization of Proton Conducting, Fluorine-Containing Block Copolymers

    OpenAIRE

    Shi, Zhi Qing

    2004-01-01

    Fuel cells are being investigated as environmental-friendly, highly efficient alternative power sources. Proton conducting membranes play a central role in proton exchange membrane fuel cells (PEMFCs), serving as both electrolyte and fuel separator. This thesis addresses the design, synthesis and characterization of novel fluorinecontaining block copolymers, and the preparation and investigation of sulfonated block copolymers as model proton exchange membranes (PEMs). Poly([vinylidene difluor...

  5. Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers

    OpenAIRE

    Weiß, Jan

    2011-01-01

    In the present thesis, the self-assembly of multi thermoresponsive block copolymers in dilute aqueous solution was investigated by a combination of turbidimetry, dynamic light scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The successive conversion of such block copolymers from a hydrophilic into a hydrophobic state includes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance. As a result, the self-organization is not following an all-or-...

  6. Ionic Liquids As Self-Assembly Guide for the Formation of Nanostructured Block Copolymer Membranes

    KAUST Repository

    Madhavan, Poornima

    2015-04-30

    Nanostructured block copolymer membranes were manufactured by water induced phase inversion, using ionic liquids (ILs) as cosolvents. The effect of ionic liquids on the morphology was investigated, by using polystyrene-b-poly(4-vinyl pyridine) (PS-b-PV4P) diblock as membrane copolymer matrix and imidazolium and pyridinium based ILs. The effect of IL concentration and chemical composition was evident with particular interaction with P4VP blocks. The order of block copolymer/ILs solutions previous to the membrane casting was confirmed by cryo scanning electron microscopy and the morphologies of the manufactured nanostructured membranes were characterized by transmission and scanning electron microscopy. Non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ILs led to a lamella-structured membrane. The rheology of the IL/block copolymer solutions was investigated, evaluating the storage and loss moduli. Most membranes prepared with ionic liquid had higher water flux than pure block copolymer membranes without additives.

  7. Rich Variety of Three-Dimensional Nanostructures Enabled by Geometrically Constraining Star-like Block Copolymers.

    Science.gov (United States)

    Wang, Chao; Xu, Yuci; Li, Weihua; Lin, Zhiqun

    2016-08-01

    The influence of star-like architecture on phase behavior of star-like block copolymer under cylindrical confinement differs largely from the bulk (i.e., nonconfinement). A set of intriguing self-assembled morphologies and the corresponding phase diagrams of star-like (AB)f diblock copolymers with different numbers of arms f (i.e., f = 3, 9, 15, and 21) in four scenarios (ϕA = 0.3 and V0 > 0; ϕA = 0.3 and V0 0; and ϕA = 0.7 and V0 0 represent that the pore wall of cylindrical confinement prefers the inner A block (i.e., A-preferential) and B block (i.e., B-preferential), respectively) were for the first time scrutinized by employing the pseudospectral method of self-consistent mean-field theory. Surprisingly, a new nanoscopic phase, that is, perforated-lamellae-on-cylinder (denoted PC), was observed in star-like (AB)3 diblock copolymer at ϕA = 0.3 and V0 > 0. With a further increase in f, a single lamellae (denoted L1) was found to possess a larger phase region. Under the confinement of A-preferential wall (i.e., V0 0, where an inverted cylinder was formed in bulk, the PC phase became stable, and its free energy decreased as f increased, suggesting the propensity to form PC phase under this condition. Moreover, in stark contrast to the phase transition of C1 → L1 → PC (C1, a single cylindrical microdmain) at ϕA = 0.3 and V0 > 0, when subjected to the A-preferential wall (ϕA = 0.7), a different phase transition sequence (i.e., C1 → PC → L1) was identified due to the formation of a double-layer structure. On the basis of our calculations, the influence of star-like architecture on (AB)f diblock copolymer under the imposed cylindrical confinement, particularly the shift of the phase boundaries as a function of f, was thoroughly understood. These self-assembled nanostructures may hold the promise for applications as lithographic templates for nanowires, photonic crystals, and nanotechnology. PMID:27389278

  8. Mechano-responsive hydrogels crosslinked by reactive block copolymer micelles

    Science.gov (United States)

    Xiao, Longxi

    Hydrogels are crosslinked polymeric networks that can swell in water without dissolution. Owing to their structural similarity to the native extracelluar matrices, hydrogels have been widely used in biomedical applications. Synthetic hydrogels have been designed to respond to various stimuli, but mechanical signals have not incorporated into hydrogel matrices. Because most tissues in the body are subjected to various types of mechanical forces, and cells within these tissues have sophisticated mechano-transduction machinery, this thesis is focused on developing hydrogel materials with built-in mechano-sensing mechanisms for use as tissue engineering scaffolds or drug release devices. Self-assembled block copolymer micelles (BCMs) with reactive handles were employed as the nanoscopic crosslinkers for the construction of covalently crosslinked networks. BCMs were assembled from amphiphilic diblock copolymers of poly(n-butyl acrylate) and poly(acrylic acid) partially modified with acrylate. Radical polymerization of acrylamide in the presence of micellar crosslinkers gave rise to elastomeric hydrogels whose mechanical properties can be tuned by varying the BCM composition and concentration. TEM imaging revealed that the covalently integrated BCMs underwent strain-dependent reversible deformation. A model hydrophobic drug, pyrene, loaded into the core of BCMs prior to the hydrogel formation, was dynamically released in response to externally applied mechanical forces, through force-induced reversible micelle deformation and the penetration of water molecules into the micelle core. The mechano-responsive hydrogel has been studied for tissue repair and regeneration purposes. Glycidyl methacrylate (GMA)-modified hyaluronic acid (HA) was photochemically crosslinked in the presence of dexamethasone (DEX)-loaded crosslinkable BCMs. The resultant HA gels (HAxBCM) contain covalently integrated micellar compartments with DEX being sequestered in the hydrophobic core. Compared

  9. Antimicrobial activity of poly(acrylic acid) block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Gratzl, Günther, E-mail: guenther.gratzl@jku.at [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Paulik, Christian [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Hild, Sabine [Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Str. 69, 4040 Linz (Austria); Guggenbichler, Josef P.; Lackner, Maximilian [AMiSTec GmbH and Co. KG, Leitweg 13, 6345 Kössen, Tirol (Austria)

    2014-05-01

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid–base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. - Highlights: • Acrylic acid diblock copolymers are antimicrobially active. • The antimicrobial activity depends on the acrylic acid content in the copolymer. • No salts, metals or other antimicrobial agents are needed.

  10. Antimicrobial activity of poly(acrylic acid) block copolymers

    International Nuclear Information System (INIS)

    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid–base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. - Highlights: • Acrylic acid diblock copolymers are antimicrobially active. • The antimicrobial activity depends on the acrylic acid content in the copolymer. • No salts, metals or other antimicrobial agents are needed

  11. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    International Nuclear Information System (INIS)

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10−4 mg/mL and 3.9 × 10−5 mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability

  12. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups.

    Science.gov (United States)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b-poly(3,3-bis(Hydroxymethyl-triazolylmethyl) oxetane)-b-polylactide (PLA-b-PHMTYO-b-PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b-poly(3,3-Diazidomethyloxetane)-b-polylactide (PLA-b-PBAMO-b-PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following "Click" reaction of PLA-b-PBAMO-b-PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b-PHMTYO-b-PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b-PHMTYO-b-PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10(-4)mg/mL and 3.9 × 10(-5)mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b-PHMTYO-b-PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. PMID:25175206

  13. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo, E-mail: zghu@htu.cn

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10{sup −4} mg/mL and 3.9 × 10{sup −5} mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability.

  14. Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.

    Science.gov (United States)

    Lei, Y; Wang, T; Mitchell, J W; Qiu, J; Kilpatrick-Liverman, L

    2014-12-01

    Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. PMID:25248611

  15. Morphology-properties relationship on nanocomposite films based on poly(styrene-block-diene-block-styrene copolymers and silver nanoparticles

    Directory of Open Access Journals (Sweden)

    2011-02-01

    Full Text Available A comparative study on the self-assembled nanostructured morphology and the rheological and mechanical properties of four different triblock copolymers, based on poly(styrene-block-diene-block-styrene and poly(styrene-block-diene-block-styrene matrices, and of their respective nanocomposites with 1 wt% silver nanoparticles, is reported in this work. In order to obtain well-dispersed nanoparticles in the block copolymer matrix, dodecanethiol was used as surfactant, showing good affinity with both nanoparticles and the polystyrene phase of the matrices as predicted by the solubility parameters calculated based on Hoftyzer and Van Krevelen theory. The block copolymer with the highest PS content shows the highest tensile modulus and tensile strength, but also the smallest elongation at break. When silver nanoparticles treated with surfactant were added to the block copolymer matrices, each system studied shows higher mechanical properties due to the good dispersion and the good interface of Ag nanoparticles in the matrices. Furthermore, it has been shown that semiempirical models such as Guth and Gold equation and Halpin-Tsai model can be used to predict the tensile modulus of the analyzed nanocomposites.

  16. Self-organization on multiple length scales in "hairy rod"-coil block copolymer supramolecular complexes

    OpenAIRE

    Hammond, Matthew R.; Klok, Harm-Anton; Mezzenga, Raffaele

    2008-01-01

    A peptide-synthetic hybrid block copolymer, poly(ethylene oxide)-block-poly(L-glutamic acid), is shown to form supramolecular complexes with primary alkylamines of varying alkyl chain lengths (8 to 18 methylene units) in organic solvents via acid-base proton transfer and subsequent ionic bonding. The peptidic block being in the α-helical conformation, these materials behave as coil-"hairy rod" block copolymers, and show hierarchically self-organized nanostructures in the solid state. X-ray sc...

  17. Mechanism of co-nanoprecipitation of organic actives and block copolymers in a microfluidic environment

    International Nuclear Information System (INIS)

    Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine. (paper)

  18. A new drug carrier: Magnetite nanoparticles coated with amphiphilic block copolymer

    Institute of Scientific and Technical Information of China (English)

    CHANG Yu; BAI YunPeng; TENG Bao; Li ZhaoLong

    2009-01-01

    This paper reports on the synthesis and characterization of 4 nm magnetite nanoparticles coated with amphiphilic block copolymers of poly(ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PEMA-b-PHEMA) by surface-initiated atom transfer radical polymerization (ATRP), which can act as new po-tential carriers for hydrophobic targeted drug delivery. Vibrating sample magnetometer analysis indi-cated that the magnetite nanoparticles were superparamagnetic at room temperature. Thermogravim-etric analysis (TGA) was applied to studying the property of surface of magnetite nanoparticles, and the surface density of macromolecules was calculated. The grafting density of oleic acid, BrMPA and PEMA was 5.8, 3.9, 0.16 chain/nm2 respectively, which indicates that the initiation efficiency decreases due to the influence of large space of oleic acid molecules. In vitro progesterone and (-)-isoproterenol hy-drochloride release in phosphate buffered saline (PBS) at pH 7.0 and 37℃ was conducted in order to demonstrate the function of drug loading and release. The results showed that the amount of drug carried into the core-shell Fe3O4@PEMA-b-PHEMA depends on the length of hydrophobic segment of block copolymer. The release of progesterone (37% after 22 h in our previous work) was compared with the release of (-)-isoproterenol hydrochloride (80% after 50 min), demonstrating that the strong hy-drophobic interaction between hydrophobic segment and drug can effectively control the release of hydrophobic drugs.

  19. Mechanism of co-nanoprecipitation of organic actives and block copolymers in a microfluidic environment.

    Science.gov (United States)

    Capretto, Lorenzo; Cheng, Wei; Carugo, Dario; Katsamenis, Orestis L; Hill, Martyn; Zhang, Xunli

    2012-09-21

    Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine. PMID:22922560

  20. Effect of Hydrogen-Bonding Junctions on Microphase Separation in Block Copolymers

    Science.gov (United States)

    Stone, Greg; Hedrick, Jim; Nederberg, Fredrik; Balsara, Nitash

    2008-03-01

    The morphology of poly(styrene-block- trimethylene carbonate) (PS-PTMC) copolymers with and without thiourea groups at the junction between the blocks was studied by a combination of small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The thiourea groups are known to exhibit inter-molecular hydrogen bonding. We demonstrate that the presence of thiourea groups results in increased segregation between PS and PTMC blocks. We focus on symmetric systems with total molecular weights in the 5 kg/mol range. In conventional block copolymers without hydrogen bonding groups it is difficult to obtain strong segregation in low molecular weight systems because the product chi*N controls segregation (chi is the Flory-Huggins interaction parameter and N is the number of monomers per chain). The incorporation of hydrogen bonding groups may provide a route for the generation of patterns with small, sharply defined features using block copolymers.

  1. Interactions between plasma and block copolymers used in directed self-assembly patterning

    Science.gov (United States)

    Sirard, Stephen; Azarnouche, Laurent; Gurer, Emir; Durand, William; Maher, Michael; Mori, Kazunori; Blachut, Gregory; Janes, Dustin; Asano, Yusuke; Someya, Yasunobu; Hymes, Diane; Graves, David; Ellison, Christopher J.; Willson, C. Grant

    2016-03-01

    The directed self-assembly (DSA) of block copolymers offers a promising route for scaling feature sizes below 20 nm. At these small dimensions, plasmas are often used to define the initial patterns. It is imperative to understand how plasmas interact with each block in order to design processes with sufficient etch contrast and pattern fidelity. Symmetric lamella forming block copolymers including, polystyrene-b-poly(methyl methacrylate) and several high-χ silicon-containing and tin-containing block copolymers were synthesized, along with homopolymers of each block, and exposed to various oxidizing, reducing, and fluorine-based plasma processes. Etch rate kinetics were measured, and plasma modifications of the materials were characterized using XPS, AES, and FTIR. Mechanisms for achieving etch contrast were elucidated and were highly dependent on the block copolymer architecture. For several of the polymers, plasma photoemissions were observed to play an important role in modifying the materials and forming etch-resistant protective layers. Furthermore, it was observed for the silicon- and tin-containing polymers that an initial transient state exists, where the polymers exhibit an enhanced etch rate, prior to the formation of the etch-resistant protective layer. Plasma developed patterns were demonstrated for the differing block copolymer materials with feature sizes ranging from 20 nm down to approximately 5 nm.

  2. Control of Crystallization to Promote Microphase Separation in Fully Conjugated Block Copolymers

    Science.gov (United States)

    Lee, Youngmin; Le, Thinh P.; Seibers, Zach; Kilbey, S. Michael, II; Wang, Qing; Gomez, Enrique D.

    Donor -acceptor fully conjugated block copolymers, where donor and acceptor conjugated polymers are covalently bonded together, are interesting as single-component active-layer materials for photovoltaics because it can adopt mesoscale microphase separated structures with length scales comparable to the exciton diffusion length. Nevertheless, due to the strong crystallization of poly(3-hexylthiophene-2,5-diyl) (P3HT), morphologies of fully conjugated block copolymers containing P3HT are predominantly driven by crystallization as opposed to microphase separation. We control the crystallization in block copolymers to promote microphase separation in fully conjugated block copolymers through the addition of small amounts of 3-octylthiophene to the polymerization of P3HT. Poly(3-hexylthiophene-2,5-diyl- r-3-octylthiophene-2,5-diyl)-block-poly((9,9-dioctylfluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5',5''-diyl) (P3HT- b-PFTBT) copolymers were prepared by Grignard metathesis for the alkylthiophene block followed by chain extension through a Suzuki-Miyaura polycondensation. We compare the crystallization, self-assembly and performance in devices of P3HT-b-PFTBT with a few mole percent of 3-octylthiophene in the P3HT block. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831.

  3. Preparation of Pickering double emulsions using block copolymer worms.

    Science.gov (United States)

    Thompson, Kate L; Mable, Charlotte J; Lane, Jacob A; Derry, Mathew J; Fielding, Lee A; Armes, Steven P

    2015-04-14

    The rational formulation of Pickering double emulsions is described using a judicious combination of hydrophilic and hydrophobic block copolymer worms as highly anisotropic emulsifiers. More specifically, RAFT dispersion polymerization was utilized to prepare poly(lauryl methacrylate)-poly(benzyl methacrylate) worms at 20% w/w solids in n-dodecane and poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) worms at 13% w/w solids in water by polymerization-induced self-assembly (PISA). Water-in-oil-in-water (w/o/w) double emulsions can be readily prepared with mean droplet diameters ranging from 30 to 80 μm using a two-stage approach. First, a w/o precursor emulsion comprising 25 μm aqueous droplets is prepared using the hydrophobic worms, followed by encapsulation within oil droplets stabilized by the hydrophilic worms. The double emulsion droplet diameter and number of encapsulated water droplets can be readily varied by adjusting the stirring rate employed during the second stage. For each stage, the droplet volume fraction is relatively high at 0.50. The double emulsion nature of the final formulation was confirmed by optical and fluorescence microscopy studies. Such double emulsions are highly stable to coalescence, with little or no change in droplet diameter being detected over storage at 20 °C for 10 weeks as judged by laser diffraction. Preliminary experiments indicate that the complementary o/w/o emulsions can also be prepared using the same pair of worms by changing the order of homogenization, although somewhat lower droplet volume fractions were required in this case. Finally, we demonstrate that triple and even quadruple emulsions can be formulated using these new highly anisotropic Pickering emulsifiers. PMID:25834923

  4. Surface affinity role in graphoepitaxy of lamellar block copolymers

    Science.gov (United States)

    Claveau, G.; Quemere, P.; Argoud, M.; Hazart, J.; Pimenta Barros, P.; Sarrazin, A.; Posseme, N.; Tiron, R.; Chevalier, X.; Nicolet, C.; Navarro, C.

    2016-03-01

    Overcoming the optical limitations of 193nm immersion lithography can be achieved using Directed Self Assembly (DSA) of block-copolymers (BCPs) as a low-cost and versatile complementary technique. The goal of this paper is to investigate the potential of DSA to address line and space (L/S) high resolution patterning by performing the density multiplication of lines with the graphoepitaxy approach. As surface affinity is a key parameter in self-assembly, three variations, or "flavors", of DSA template affinity are investigated regarding several success criteria such as morphology control or defectivity. More precisely, both the methodology to register DSA defects and the impact of process parameters on defectivity are detailed. Using the 300mm pilot line available in LETI and Arkema's advanced materials, we investigate process optimization of DSA line/space patterning of a 38nm period lamellar PS-b-PMMA BCP (L38). For this study, our integration scheme, depicted in figure 2-1, is based on BCP self-assembly inside organic hard mask guiding patterns obtained using 193i nm lithography. Defect analysis coupled with the fine tuning of process parameters (annealing, brush material) provided the optimum conditions for the L38 self-assembly. Using such conditions, DSA using the three affinity flavors is investigated by means of SEM top-view and cross-section review. Lithographic performances of one selected flavor are then evaluated with the comparison of Process Windows (PWs) function of either commensurability, morphology or LWR. This work is a first step in finding the best process for an industrial graphoepitaxy approach.

  5. P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellular localization and drug efficiency.

    Science.gov (United States)

    Barz, Matthias; Armiñán, Ana; Canal, Fabiana; Wolf, Florian; Koynov, Kaloian; Frey, Holger; Zentel, Rudolf; Vicent, María J

    2012-10-10

    In order to explore the influence of polymer microstructure and stereochemistry in biological settings, the synthesis, micellization, cellular fate and the use in paclitaxel formulations of poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(L-lactide) (P(HPMA)-block-P(LLA)) and poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(DL-lactide) block copolymers (P(HPMA)-block-P(DLLA)) were studied. To this end, P(HPMA)-block-P(lactide) block copolymers and their fluorescently labeled analogues were synthesized. The polymers exhibited molecular weights M(n) around 20,000 g/mol with dispersities (D=M(w)/M(n)) below 1.3. In addition, the solution conformation of this new type of partially degradable amphiphilic block copolymers was studied with and without paclitaxel loading in PBS buffer (pH 7.2), employing fluorescence correlation spectroscopy (FCS). We observed polymeric micelles with a hydrodynamic diameter of 17.0 nm for a fluorescently labeled P(HPMA)-block-P(LLA) block copolymer (P2*) and 20.4 nm for a P(HPMA)-block-P(DLLA) block copolymer (P3*). For the corresponding loaded block copolymers aggregates with a diameter of 40.0 nm (P2*) and 41.4 nm (P3*) in formulations containing 17 wt.% paclitaxel were observed, respectively. While the block copolymer itself showed non-toxic behavior up to a concentration of 3 mg/mL in HeLa (human cervix adenocarcinoma) cells, the paclitaxel containing formulations showed IC 50 values in the range of 10-100 nM. The P(HPMA)-block-P(DLLA) polymer (P3*) enters the cells more efficiently than stereo regular polymer (P2*) via an energy-dependent uptake mechanism. Thus, differences in the IC(50) value are--most likely--attributed to significant changes in cellular uptake. Polymer tacticity and stereoregularity appear to represent a key feature determining cellular uptake and efficiency for the PLA block copolymer drug formulations. This work demonstrates the importance of the microstructure of polymers used in drug delivery systems (DDS

  6. Synthesis and characterization of polystyrene-poly(ethylene oxide)-heparin block copolymers

    OpenAIRE

    Vulić, I.; Okano, T.; Kim, S W; J. Feijen

    1988-01-01

    A procedure for the preparation of new block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic spacer-block of poly(ethylene oxide) and a bioactive block of heparin was investigated. Polystyrene with one amino group per chain was synthesized by free radical oligomerization of styrene in dimethylformamide, using 2-aminoethanethiol as a chain transfer agent. This amino group was used in the coupling reaction with amino-telechelic poly(ethylene oxide) to produce an AB type...

  7. Improved synthesis of polystyrene-poly(ethylene oxide)-heparin block copolymers

    OpenAIRE

    Vulic, I.; Loman, A.J.B.; J. Feijen; Okano, T.; Kim, S W

    1990-01-01

    A novel procedure for the synthesis of block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic block of poly(ethylene oxide) and a bioactive block of nitrous acid-degraded heparin was developed. Amino-semitelechelic polystyrene was prepared by anionic polymerization of styrene in cyclohexane, using sec-butyllithium as initiator and N-(benzylidene)trimethylsilylamide as terminator. After purification using preparative column chromatography, polystyrene with one amino gro...

  8. Construction and characterization of hybrid nanoparticles via block copolymer blends and kinetic control of solution assembly

    Science.gov (United States)

    Chen, Yingchao

    Amphiphilic block copolymers are able to self-assemble into well-defined nanostructures in aqueous solutions or aqueous/miscible organic solutions. These structures include traditional spheres, cylinders and vesicles, which mimic nanostructures formed by small molecule analogs like lipids and surfactants. The large molecular weight and complex macromolecular architectures provide several advantages over small molecule amphiphiles, including the large chemical versatility, control over the size and shape of the solution assemblies, unique slow chain exchange and exceptional increased versatility in possible nanostructures. These advantages have motivated the noteworthy study of constructing well-defined, controlled and, especially, multicompartment and multigeometry polymeric nanoobjects for potential multiple nanotechnology applications. To reach complexity and well-controlled nanostructures, the facile utility and fundamental understanding of the parameters that influence the effective construction of solution assemblies needs to be continued. Given these motivations, this dissertation demonstrated the design of block copolymers, manipulation of kinetic control parameters of solution assembly, and characterization of hybrid nanostructures with the aim of creating new, well-defined nanostructures. The first objective of this dissertation was to explore the effects of solvent processing rates in influencing multicompartment and multigeometry nanoparticle construction, structure evolution over long-time aging and nanoparticle formation mechanisms. The noticeable effects of water addition rates on the formation of various nanostructures were studied by cryogenic transmission electron microscopy, selective staining and small angle scattering. It was revealed that the water addition rate have significant influence over the final assemblies in block copolymer blends. New shapes of multicompartment and multigeometry nanoparticles have been constructed including hybrid

  9. Self-Assembled Structures of PMAA-PMMA Block Copolymers : Synthesis, Characterization, and Self-Consistent Field Computations

    NARCIS (Netherlands)

    Li, Feng; Schellekens, Mike; de Bont, Jens; Peters, Ron; Overbeek, Ad; Leermakers, Frans A. M.; Tuinier, Remco

    2015-01-01

    Block copolymers composed of methacrylic acid (MAA) and methyl methacrylate (MMA) blocks are interesting candidates for replacing surfactants in emulsion polymerization methods. Here the synthesis and experimental characterization of well-defined PMAA-PMMA block copolymers made via RAFT polymerizati

  10. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

    OpenAIRE

    Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Son, Gyung Mo; Jeong, Young-IL; Kwak, Tae-Won; Kim, Do Hyung; Chung, Chung-Wook; Rhee, Young Ha; Kang, Dae Hwan; Kim, Hyung Wook

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a 1H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes...

  11. Analytic Structure of the SCFT Energy Functional of Multicomponent Block Copolymers

    CERN Document Server

    Jiang, Kai; Zhang, Pingwen

    2013-01-01

    This paper concerns the analytic structure of the self-consistent field theory (SCFT) energy functional of multicomponent block copolymer systems which contain more than two chemically distinct blocks. The SCFT has enjoyed considered success and wide usage in investigation of the complex phase behavior of block copolymers. It is well-known that the physical solutions of the SCFT equations are saddle points, however, the analytic structure of the SCFT energy functional has received little attention over the years. A recent work by Fredrickson and collaborators [see the monograph by Fredrickson, The Equilibrium Theory of Inhomogeneous Polymers, (2006), pp. 203-209] has analysed the mathematical structure of the field energy functional for polymeric systems, and clarified the index-1 saddle point nature of the problem produced by the incompressibility constraint. In this paper, our goals are to draw further attention to multicomponent block copolymers utilizing the Hubbard-Stratonovich transformation used by Fre...

  12. The Organization of Nanoporous Structure Using Controlled Micelle Size from MPEG-b-PDLLA Block Copolymers

    International Nuclear Information System (INIS)

    Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 A with the increase of hydrophobic chain lengths and up to 660 m2/g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state 13C and 29Si NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates

  13. 125l-Labeled PEO/PLA block copolymer: biodistribution studies in rats

    Czech Academy of Sciences Publication Activity Database

    Nováková, K.; Lázníček, M.; Rypáček, František; Machová, Luďka

    2002-01-01

    Roč. 17, č. 4 (2002), s. 285-296. ISSN 0883-9115 R&D Projects: GA AV ČR KSK4055109 Institutional research plan: CEZ:AV0Z4050913 Keywords : block copolymer micelles * poly(D,L-lactide-block-ethylene oxide) * biodistribution Subject RIV: CC - Organic Chemistry Impact factor: 0.525, year: 2002

  14. Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes

    Science.gov (United States)

    Fujimoto, Cy H.; Hibbs, Michael; Ambrosini, Andrea

    2012-02-07

    Improved multi-block sulfonated poly(phenylene) copolymer compositions, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cells, in electrode casting solutions and electrodes. The multi-block architecture has defined, controllable hydrophobic and hydrophilic segments. These improved membranes have better ion transport (proton conductivity) and water swelling properties.

  15. Polymer Segmental Cross-Correlations from Dielectric Relaxation Spectra of Block Copolymers

    OpenAIRE

    Phillies, George D. J.

    2011-01-01

    Dielectric relaxation spectra of block polymers containing sequential type-A dipoles are considered. Spectra of a specific set of block copolymers can be combined to isolate the dynamic cross-correlation between the motions of two distinct parts of the same polymer chain. Unlike past treatments of this problem, no model is assumed for the underlying polymer dynamics.

  16. Photocatalytic Nanostructuring of Graphene Guided by Block Copolymer Self-Assembly

    DEFF Research Database (Denmark)

    Wang, Zhongli; Li, Tao; Schulte, Lars;

    2016-01-01

    graphene nanomesh was fabricated by photocatalysis of single-layer graphene suspended on top of TiO2-covered nanopillars, which were produced by combining block copolymer nanolithography with atomic layer deposition. Graphene nanoribbons were also prepared by the same method applied to a line-forming block...

  17. The effects of ethylene oxide containing lipopolymers and tri-block copolymers on lipid bilayers of dipalmitoylphosphatidylcholine

    DEFF Research Database (Denmark)

    Baekmark, T. R.; Pedersen, S.; Jorgensen, K.; Mouritsen, Ole G.

    1997-01-01

    oxide moity, anchored to the bilayer by a 1,2-dioctadecanoyl-s,n-glycero-3-phosphoethanolamine (DC18PE) lipid. The second type, which is a novel type of membrane-spanning object, is an amphiphilic tri-block copolymer composed of two hydrophilic stretches of polyethylene oxide separated by a hydrophobic......A comparative study is conducted on the influence of two types of polymeric compounds on the phase behavior of 1,2-dihexadecanoyl-s,n-glycero-3-phosphotidylcholine (DC16PC) lipid bilayers. The first polymeric compound is a lipopolymer, mer, with two different lengths of a hydrophilic polyethylene...... stretch of polystyrene. Hence the tri-block copolymer may act as a membrane-spanning macromolecule mimicking an amphiphilic protein or polypeptide. Differential scanning calorimetry is used to determine a partial phase diagram for the lipopolymer systems and to assess the amount of lipopolymer that can be...

  18. Melt and Solid-State Structures of Polydisperse Polyolefin Block Copolymers

    Science.gov (United States)

    Register, Richard; Li, Sheng

    2013-03-01

    Recent developments in coordinative chain transfer polymerization have enabled the synthesis of ethylene-co-octene block copolymers, where the blocks are either crystallizable (an ethylene-co-octene random copolymer block with low octene content) or amorphous (analogous block with high octene content). With a suitable choice of catalyst type(s) and reactor train configuration, accessible chain architectures include diblock, where each block ideally has the most-probable distribution of chain lengths, and multiblock, where both the individual blocks and the number of blocks per chain follow the most-probable distribution. With a sufficiently large interblock octene differential, block copolymers of both architectures, containing roughly equal masses of the two types of block, self-assemble in the melt into well-ordered lamellar structures, despite the large polydispersity. Interblock mixing, induced by the modest Flory interaction parameter and the broad distribution of block lengths, yields an enormous domain spacing (> 100 nm) despite the relatively low average block molecular weights (< 50 kg/mol). Extensive interblock mixing also allows the polyethylene crystals to grow freely and nearly isotropically across the domain interfaces, while preserving the domain structure present in the melt; in the solid state, the optical and x-ray contrasts between dissimilar domains are greatly enhanced due to their different levels of crystallinity. (Work conducted in collaboration with Jeffrey Weinhold, Philip Hustad, and Brian Landes of Dow Chemical Core R&D.) Support from the NSF Polymers Program (DMR-1003942).

  19. DETERMINATION OF THE CRYSTALLINITY IN DIFFERENT TYPE POLY (OXYETHYLENE -STYRENE )BLOCK COPOLYMERS BY X- RAY DIFFRACTION METHOD

    Institute of Scientific and Technical Information of China (English)

    YAO Ning

    1989-01-01

    By means of the intensity theory of X- ray scattering and the two - phase concept of high polymer, the basic formula of the crystallinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene - styrene) block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene - styrene) block copolymers increases with the increase of the EO content and decreases in the order: PEO - PS - PEO > PEO - PS > PS - PEO - PS.

  20. Interaction between Albumin and Pluronic F127 Block Copolymer Revealed by Global and Local Physicochemical Profiling.

    Science.gov (United States)

    Neacsu, Maria Victoria; Matei, Iulia; Micutz, Marin; Staicu, Teodora; Precupas, Aurica; Popa, Vlad Tudor; Salifoglou, Athanasios; Ionita, Gabriela

    2016-05-12

    The interaction of human serum albumin (HSA) with amphiphilic block copolymer Pluronic F127 has been investigated by several physical methods. Interest in studying this system stems from a broad range of bioactivities involving both macromolecules. Serum albumins constitute a significant class of proteins in the circulatory system, acting as carriers for a wide spectrum of compounds or assemblies. Pluronic block copolymers have revealed their capacity to ferry a variety of biologically active compounds. Circular dichroism, rheological measurements, and differential scanning microcalorimetry (μDSC) were employed to get insight into the interaction betweeen the two macromolecules. The results reveal that Pluronic F127 induces conformational changes to albumin if it is organized in a micellar form, while albumin influences the self-assembly of Pluronic F127 into micelles or gels. F127 micelles, however, induce smaller conformational changes compared to ionic surfactants. The μDSC thermograms obtained for HSA and/or F127 show that HSA shifts the critical micellar temperature (cmt) to lower values, while concurrently the HSA denaturation behavior is influenced by F127, depending on its concentration. Rheological measurements on solutions of F127 17% have shown that a sol-to-gel transition occurs at higher temperatures in the presence of HSA and the resulting gel is weaker. The global profile on HSA/F127 systems was complemented by local information provided by EPR measurements. A series of X-band EPR experiments was performed with spin probes 4-(N,N'-dimethyl-N-hexadecyl)ammonium-2,2',6,6'-tetramethylpiperidine-1-oxyl iodide (CAT16) and 5-doxyl stearic acid (5-DSA). These spin probes bind to albumin sites and are sensitive to phase transformations in Pluronic block copolymer solutions. For a given F127 concentration, the spin probe binds only to HSA below cmt and migrates to the F127 micelles above cmt. The collective data suggest soft interactions between the

  1. The morphology and fabrication of nanostructured micelle by a novel block copolymer with linear–dendritic structure

    International Nuclear Information System (INIS)

    We report here a novel approach to fabricate a nanostructured micelle as potential drug carriers and the relationship between the morphological structure and the preparation condition. The polymeric micelle aggregates constructed by self-assembly compose of the poly(ε-caprolactone)/monomethoxy poly(ethylene glycol) linear–dendritic block copolymers. The corresponding copolymers were synthesized by using ring opening polymerization of ε-caprolactone (CL) and a dendritic poly(ether–amide) (DPEA-OH) as an initiator, then coupling with the isocyanate end-capped linear monomethoxy polyethylene glycol. Fluorescence spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were performed to characterize the copolymer micelles. The critical micelle concentration (CMC) was determined to be 1.623 mg/L. The hydrodynamic radius (Rh) and the polydispersity index (PDI) are influenced by the concentration of the micelle solutions. The multiple morphologies of the micelle aggregates, including spheres, rob-like dendritic structure and vesicles were observed, which the variety depends on the various preparation conditions. The nanostructured micelles based on the linear–dendritic block copolymer possess the strong thermodynamic stability and the power of solubilization of hydrophobic drug molecules. Highlights: ► Novel PCL/mPEG based on dendritic structure hybrid micelles was successful1y fabricated. ► They were self-aggregated as nanoscale micelle in water with various morphologies. ► The spherical micelles can act as new potential hydrophobic drug nanocarriers

  2. Epitaxial relationships for hexagonal-to-cubic phase transition in a block copolymer mixture

    DEFF Research Database (Denmark)

    Schulz, M.F.; Bates, F.S.; Almdal, K.;

    1994-01-01

    Small-angle neutron scattering experiments have revealed an epitaxial relationship between the hexagonal cylinder phase, and a bicontinuous cubic phase with Ia3dBAR space group symmetry, in a poly(styrene)-poly(2-vinylpyridine) diblock copolymer mixture. Proximity to the order-disorder transition...... and an inelastic low frequency rheological response suggest that the cubic phase is stabilized by fluctuations. These results identify block copolymers as model compounds for investigating the thermodynamics and dynamics of complex ''soft'' condensed matter....

  3. An Observation on the Microphase Separation of Poly(methyl methacrylate)-block-Polystyrene Copolymer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The phase behavior of a well-defined poly(methyl methacrylate)-b-polystyrene block copolymer was studied by transmission electron microscope.The results show that a microphase transition may have occurred in the copolymer film.A kind of lamellae and an ordered bicontinuous double-diamond morphology are observed clearly.The lamellar morphology reveals a larger period of about 400 nm.

  4. Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

    International Nuclear Information System (INIS)

    The morphology and magnetic properties of diblock copolymer templated ferrimagnetic cobalt oxide nanoparticles are reported. Ring opening metathesis polymerization (ROMP) was used to synthesize a novel cobalt diblock copolymer, where cobalt is directly attached to the polymer chain. Gel permeation chromatography (GPC) was performed to determine molecular weight distribution. Transmission electron microscope (TEM), UV-Vis, FTIR, and vibrating sample magnetometer (VSM) were used to characterize the block copolymer nanocomposite. The nanocomposite films were weakly ferrimagnetic at room temperature. The cobalt oxide nanoparticles were uniformly dispersed within the polymer matrix with an average radius of 4.9+/-0.9nm

  5. Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sufi R. [Department of Chemical Engineering, University of Maryland, College Park, MD 20742-2111 (United States); Kofinas, Peter [Department of Chemical Engineering, University of Maryland, College Park, MD 20742-2111 (United States)]. E-mail: kofinas@umd.edu

    2005-03-01

    The morphology and magnetic properties of diblock copolymer templated ferrimagnetic cobalt oxide nanoparticles are reported. Ring opening metathesis polymerization (ROMP) was used to synthesize a novel cobalt diblock copolymer, where cobalt is directly attached to the polymer chain. Gel permeation chromatography (GPC) was performed to determine molecular weight distribution. Transmission electron microscope (TEM), UV-Vis, FTIR, and vibrating sample magnetometer (VSM) were used to characterize the block copolymer nanocomposite. The nanocomposite films were weakly ferrimagnetic at room temperature. The cobalt oxide nanoparticles were uniformly dispersed within the polymer matrix with an average radius of 4.9+/-0.9nm.

  6. First observation of an ordered microphase in melts of poly(oxyethylene)-poly(oxypropylene) block copolymers

    DEFF Research Database (Denmark)

    Patrick, J.; Fairclough, J.P.A.; Yu, G.E.;

    2000-01-01

    The first observation of ordered microphase structures in poly(oxyethylene)-poly(oxypropylene) diblock copolymers melts is reported. Two diblock copolymers were synthesised by anionic polymerisation, i.e. E130P58 and E107P69 where E represents an oxyethylene unit, OCH2CH2, and P an oxypropylene...... triblock copolymer with perdeuterated P blocks, E(33)dP(42)E(33), was synthesised and studied in the melt phase by small-angle neutron scattering. This allowed determination of the temperature dependence of the Flory-Huggins interaction parameter for the poly(oxyethylene)-poly(oxypropylene) system, i...

  7. Small angle neutron scattering study of the micelle structure of amphiphilic block copolymers

    International Nuclear Information System (INIS)

    The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H2O/D2O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain was confirmed to have an ellipsoidal shape

  8. Block copolymer directed synthesis of mesoporous TiO 2 for dye-sensitized solar cells

    KAUST Repository

    Nedelcu, Mihaela

    2009-01-01

    The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block- ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure and its influence upon solar cell performance is investigated. Furthermore, the use of a partially sp 2 hybridized structure directing polymer enables the crystallization of porous TiO2 networks at high temperatures without pore collapse, improving its performance in solid-state dye-sensitized solar cells. © 2009 The Royal Society of Chemistry.

  9. Studies on microphase-separated structures of block copolymers by neutron reflectivity measurement

    International Nuclear Information System (INIS)

    Segmental distributions of block copolymer chains in lamellar microphase-separated structure and those of homopolymers in block copolymer/homopolymer blends also with lamellar structures were studied by neutron reflectivity measurements. It was revealed that polystyrene and poly(2-vinylpyridine) lamellae were alternately stacked within the thin films of pure block copolymers spin-coated on silicon wafers, and they were preferentially oriented along the direction parallel to film surface. Polystyrene lamella appeared at air surfaces of the films, while poly(2-vinylpyridine) lamella did on silicon surfaces. Segment distribution at lamellar interface was well described by an error function, and the width of the lamellar interface, defined by a full-width half-maximum value of interfacial profile, was estimated to be about 4.5 nm. Segments of block chains adjacent to the chemical junction points connecting different block chains were strongly localized near the lamellar interfaces, while those on the free ends of block chains were distributed all over the lamellar microdomains with their distribution maxima at the centers of lamellae. On the other hand, it was clarified that homopolymers dissolved in the corresponding lamellar microdomains of block copolymers were also distributed throughout the microdomains with their concentration maxima at the centers of the lamellae. (author)

  10. Structure and ionic conductivity of block copolymer electrolytes over a wide salt concentration range

    Science.gov (United States)

    Chintapalli, Mahati; Le, Thao; Venkatesan, Naveen; Thelen, Jacob; Rojas, Adriana; Balsara, Nitash

    Block copolymer electrolytes are promising materials for safe, long-lasting lithium batteries because of their favorable mechanical and ion transport properties. The morphology, phase behavior, and ionic conductivity of a block copolymer electrolyte, SEO mixed with LiTFSI was studied over a wide, previously unexplored salt concentration range using small angle X-ray scattering, differential scanning calorimetry and ac impedance spectroscopy, respectively. SEO exhibits a maximum in ionic conductivity at twice the salt concentration that PEO, the homopolymer analog of the ion-containing block, does. This finding is contrary to prior studies that examined a more limited range of salt concentrations. In SEO, the phase behavior of the PEO block and LiTFSI closely resembles the phase behavior of homopolymer PEO and LiTFSI. The grain size of the block copolymer morphology was found to decrease with increasing salt concentration, and the ionic conductivity of SEO correlates with decreasing grain size. Structural effects impact the ionic conductivity-salt concentration relationship in block copolymer electrolytes. SEO: polystyrene-block-poly(ethylene oxide); also PS-PEO LiTFSI: lithium bis(trifluoromethanesulfonyl imide

  11. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    International Nuclear Information System (INIS)

    Highlights: • A series of PDMS-b-QPDMAEMA block copolymers were synthesized via RAFT polymerization. • The composition and morphology of the copolymer films strongly depended on the content of QPDMAEMA. • Migration of QPDMAEMA blocks toward surface was promoted when contacting with water. • Heterogeneous film surfaces with higher N+ content exhibited more obvious antimicrobial activity. - Abstract: Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N+ content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings

  12. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Xiaoshuai; Li, Yancai; Zhou, Fang; Ren, Lixia; Zhao, Yunhui, E-mail: zhaoyunhui@tju.edu.cn; Yuan, Xiaoyan

    2015-02-15

    Highlights: • A series of PDMS-b-QPDMAEMA block copolymers were synthesized via RAFT polymerization. • The composition and morphology of the copolymer films strongly depended on the content of QPDMAEMA. • Migration of QPDMAEMA blocks toward surface was promoted when contacting with water. • Heterogeneous film surfaces with higher N{sup +} content exhibited more obvious antimicrobial activity. - Abstract: Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N{sup +} content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings.

  13. Thermosensitive PNIPAM-b-HTPB block copolymer micelles: molecular architectures and camptothecin drug release.

    Science.gov (United States)

    Luo, Yan-Ling; Yang, Xiao-Li; Xu, Feng; Chen, Ya-Shao; Zhang, Bin

    2014-02-01

    Two kinds of thermo-sensitive poly(N-isoproplacrylamide) (PNIPAM) block copolymers, AB4 four-armed star multiblock and linear triblock copolymers, were synthesized by ATRP with hydroxyl-terminated polybutadiene (HTPB) as central blocks, and characterization was performed by (1)H NMR, FT-IR and SEC. The multiblock copolymers could spontaneously assemble into more regular spherical core-shell nanoscale micelles than the linear triblock copolymer. The physicochemical properties were detected by a surface tension technique, nano particle analyzer, TEM, DLS and UV-vis measurements. The multiblock copolymer micelles had lower critical micelle concentration than the linear counterpart, TEM size from 100 to 120 nm and the hydrodynamic diameters below 150 nm. The micelles exhibited thermo-dependent size change, with low critical solution temperature about 33-35 °C. The characteristic parameters were affected by the composition ratios, length of PNIPAM blocks and molecular architectures. The camptothecin release demonstrated that the drug release was thermo-responsive, accompanied by the temperature-induced structural changes of the micelles. MTT assays were performed to evaluate the biocompatibility or cytotoxicity of the prepared copolymer micelles. PMID:24184534

  14. Thermoresponsive and Redox Behaviors of Poly(N-isopropylacrylamide)-Based Block Copolymers Having TEMPO Groups as Their Side Chains

    OpenAIRE

    Toru Uemukai; Tomoya Hioki; Manabu Ishifune

    2013-01-01

    Thermoresponsive and redox-active block copolymers having 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties have been synthesized by using the reversible addition-fragmentation chain transfer (RAFT) polymerization technique. N-Isopropylacrylamide (NIPAAm) and 2,2,6,6-tetramethylpiperidyl methacrylate (TEMPMA) monomers were copolymerized stepwise under RAFT polymerization conditions to afford the thermoresponsive block copolymers, PNIPAAm-block-PTEMPMA and PNIPAAm-block-PTEMPMA-block-PNIPA...

  15. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    NARCIS (Netherlands)

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in p

  16. Synthesis of Carboxylic Block Copolymers via Reversible Addition Fragmentation Transfer Polymerization for Tooth Erosion Prevention

    OpenAIRE

    Lei, Y.; Wang, T.; Mitchell, J. W.; Qiu, J.; Kilpatrick-Liverman, L.

    2014-01-01

    Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA blo...

  17. A functionalizable reverse thermal gel based on a polyurethane/PEG block copolymer

    OpenAIRE

    Park, Daewon; Wu, Wei; Wang, Yadong

    2011-01-01

    Injectable reverse thermal gels have great potentials as biomaterials for tissue engineering and drug delivery. However, most existing gels lack functional groups that can be modified with biomolecules that can guide cell/material interactions. We created an amine-functionalized ABA block copolymer, poly(ethylene glycol)-poly(serinol hexamethylene urethane), or ESHU. This reverse thermal gel consists of a hydrophobic block (B): poly(serinol hexamethylene urethane) and a hydrophilic block (A):...

  18. Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization

    OpenAIRE

    Garnier, Sébastien; Laschewsky, André

    2006-01-01

    Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of...

  19. Pattern Transfer of Sub-10 nm Features via Tin-Containing Block Copolymers

    OpenAIRE

    Maher, Michael J.; Mori, Kazunori; Sirard, Stephen M.; Dinhobl, Andrew M.; Bates, Christopher M.; Gurer, Emir; Blachut, Gregory; Lane, Austin P.; Durand, William J.; Carlson, Matthew C.; Strahan, Jeffrey R.; Ellison, Christopher J.; Willson, C. Grant

    2016-01-01

    Tin-containing block copolymers were investigated as materials for nanolithographic applications. Poly(4-trimethylstannylstyrene-block-styrene) (PSnS-PS) and poly(4-trimethylstannylstyrene-block-4-methoxystyrene) (PSnS-PMOST) synthesized by reversible addition–fragmentation chain transfer polymerization form lamellar domains with periodicities ranging from 18 to 34 nm. Thin film orientation control was achieved by thermal annealing between a neutral surface treatment and a top coat. Incorpora...

  20. Selective Semiconductor Nanocluster Deposition on Eptaxially Patterned Semicrystalline Block Copolymer Film

    Science.gov (United States)

    Park, Cheolmin; Lee, Jinwook; Jensen, Klavs F.; Bawendi, Moungi G.; Thomas, Edwin L.

    2001-03-01

    Monodisperse ZnS encapsulated CdSe semiconductor nanoclusters are sequestered in between the crystalline polyethylene (PE) lamellae of poly (ethylene-b-ethylene-alt-propylene-b ethylene) semicrystalline triblock copolymer epitaxially crystallized on single crystal of anthracene (AN). Epitaxy between PE block and An created a cross oriented texture of the edge-on crystalline PE lamellae in the thin film. At the same time, the nanoclusters, initially dissolved in the mixture of block copolymer and AN, were rejected out of the crystalline lamellae during epitaxial crystallization and selectively deposited in the amorphous region of the block copolymer. Selective distribution of nanoclusters on the cross oriented pattern structure is clearly evidenced by selected area diffraction (SAD) and bright field transmission electron microscope (TEM).

  1. Synthesis of Dumbbell-shaped Hyperbranched Amphiphilic Block Copolymer by Controlled Atom Transfer Radical Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Kyoung; An, Sung Guk; Cho, Chang Gi [Center for Advanced Functional Polymers, Department of Fiber and Polymer Science, Hanyang University, Seoul (Korea); Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea)

    2001-04-01

    Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol)(PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by {sup 1}H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for {sup 1}H-NMR spectroscopic analysis. 29 refs., 8 figs., 2 tabs.

  2. AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid) were synthesized by iodidemediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate) as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R(polystyrene)3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R(polystyrene-b-poly(tert-butyl acrylate))3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R(polystyrene-b-poly(acrylic acid))3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))3 under acidic condition.

  3. Amphiphilic block copolymers in oil-water-surfactant mixtures: efficiency boosting, structure, phase behaviour and mechanism

    Science.gov (United States)

    Gompper, G.; Richter, D.; Strey, R.

    2001-10-01

    The effect of amphiphilic block copolymers on the phase behaviour and structure of ternary microemulsions in water, oil and non-ionic surfactant mixtures is reviewed. Recent experiments have revealed that the addition of small amounts of polyethylenepropylene-polyethyleneoxide block copolymer to the ternary systems leads to a dramatic increase in the volumes of oil and water solubilized into a bicontinuous microemulsion for a given surfactant volume fraction. While phase diagrams directly show the power of the amphiphilic block copolymers as efficiency boosters, the theoretical analysis in terms of bending energy discloses the mechanism for the efficiency boosting as due to the variation of the surfactant film curvature elasticity by tethered polymers in the form of mushrooms at the interface. Neutron scattering experiments employing a high-precision two-dimensional contrast variation technique confirm this picture and demonstrate that the polymer molecules uniformly decorate the surfactant film.

  4. Three-dimensional inverse design of nanopatterns with block copolymers and homopolymers

    Science.gov (United States)

    Xu, Dan; Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan

    2016-02-01

    We propose a facile inverse design strategy to generate three-dimensional (3D) nanopatterns by using either block copolymers or a binary homopolymer blend via dissipative particle dynamics simulations. We find that the composition window of block copolymers to form a specific 3D morphology can be expanded when the self-assembly of block copolymers is directed by templates. We also find that a binary homopolymer blend can serve as a better candidate in the inverse templating design, since they have similar performances on recovering the target pattern, with much lower cost. This strategy is proved efficient for fabricating templates with desired topographical configuration, and the inverse design idea sheds lights on better control and design of materials with complex nanopatterns.

  5. Three-dimensional inverse design of nanopatterns with block copolymers and homopolymers.

    Science.gov (United States)

    Xu, Dan; Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan

    2016-03-01

    We propose a facile inverse design strategy to generate three-dimensional (3D) nanopatterns by using either block copolymers or a binary homopolymer blend via dissipative particle dynamics simulations. We find that the composition window of block copolymers to form a specific 3D morphology can be expanded when the self-assembly of block copolymers is directed by templates. We also find that a binary homopolymer blend can serve as a better candidate in the inverse templating design, since they have similar performances on recovering the target pattern, with much lower cost. This strategy is proved efficient for fabricating templates with desired topographical configuration, and the inverse design idea sheds lights on better control and design of materials with complex nanopatterns. PMID:26880143

  6. Selective directed self-assembly of coexisting morphologies using block copolymer blends

    Science.gov (United States)

    Stein, A.; Wright, G.; Yager, K. G.; Doerk, G. S.; Black, C. T.

    2016-08-01

    Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. Here we expand on traditional DSA chemical patterning. A blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This is in contrast to the typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist.

  7. Tuning of Block Copolymer Membrane Morphology through Water Induced Phase Inversion Technique

    KAUST Repository

    Madhavan, Poornima

    2016-06-01

    Isoporous membranes are attractive for the regulation and detection of transport at the molecular level. A well-defined asymmetric membranes from diblock copolymers with an ordered nanoporous membrane morphologies were fabricated by the combination of block copolymer self-assembly and non-solvent-induced phase separation (NIPS) technique. This is a straightforward and fast one step procedure to develop integrally anisotropic (“asymmetric”) membranes having isoporous top selective layer. Membranes prepared via this method exhibit an anisotropic cross section with a thin separation layer supported from underneath a macroporous support. These membrane poses cylindrical pore structure with ordered nanopores across the entire membrane surfaces with pore size in the range from 20 to 40 nm. Tuning the pore morphology of the block copolymer membranes before and after fabrication are of great interest. In this thesis, we first investigated the pore morphology tuning of asymmetric block copolymer membrane by complexing with small organic molecules. We found that the occurrence of hydrogen-bond formation between PS-b-P4VP block copolymer and –OH/ –COOH functionalized organic molecules significantly tunes the pore morphology of asymmetric nanoporous membranes. In addition, we studied the complexation behavior of ionic liquids with PS-b-P4VP block copolymer in solutions and investigated their effect on final membrane morphology during the non-solvent induced phase separation process. We found that non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ionic liquids led to a lamella-structured membrane. Secondly, we demonstrated the catalytic activity of the gold nanoparticle-enhanced hollow fiber membranes by the reduction of nitrophenol. Also, we systematically investigated the pore morphology of isoporous PS-b-P4VP using 3D imaging technique. Thirdly, we developed well-distributed silver nanoparticles on the

  8. Micellization kinetics in block copolymer solutions : Scaling model

    NARCIS (Netherlands)

    Dormidontova, EE

    1999-01-01

    The kinetics of micelle evolution of diblock copolymers from unimers toward the equilibrium state is studied analytically on the basis of consideration of the kinetic equations. The association/dissociation rate constants for unimer insertion/expulsion and micelle fusion/fission are calculated by ap

  9. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    International Nuclear Information System (INIS)

    Monte Carlo simulations are performed on a simple cubic lattice to investigate the behavior of a single linear multiblock copolymer chain of various lengths N. The chain of type (AnBn)m consists of alternating A and B blocks, where A are solvophilic and B are solvophobic and N = 2nm. The conformations are classified in five cases of globule formation by the solvophobic blocks of the chain. The dependence of globule characteristics on the molecular weight and on the number of blocks, which participate in their formation, is examined. The focus is on relative high molecular weight blocks (i.e., N in the range of 500–5000 units) and very differing energetic conditions for the two blocks (very good—almost athermal solvent for A and bad solvent for B). A rich phase behavior is observed as a result of the alternating architecture of the multiblock copolymer chain. We trust that thermodynamic equilibrium has been reached for chains of N up to 2000 units; however, for longer chains kinetic entrapments are observed. The comparison among equivalent globules consisting of different number of B-blocks shows that the more the solvophobic blocks constituting the globule the bigger its radius of gyration and the looser its structure. Comparisons between globules formed by the solvophobic blocks of the multiblock copolymer chain and their homopolymer analogs highlight the important role of the solvophilic A-blocks

  10. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Rissanou, Anastassia N., E-mail: rissanou@tem.uoc.gr [Department of Mathematics and Applied Mathematics, University of Crete, GR-71003 Heraklion Crete, Greece and Archimedes Center for Analysis, Modeling and Computation, University of Crete, P.O. Box 2208, GR-71003 Heraklion Crete (Greece); Tzeli, Despoina S. [Department of Materials Science and Technology, University of Crete, GR-71003 Heraklion Crete (Greece); Anastasiadis, Spiros H. [Department of Chemistry, University of Crete, P.O. Box 2208, 710 03 Heraklion Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece); Bitsanis, Ioannis A. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece)

    2014-05-28

    Monte Carlo simulations are performed on a simple cubic lattice to investigate the behavior of a single linear multiblock copolymer chain of various lengths N. The chain of type (A{sub n}B{sub n}){sub m} consists of alternating A and B blocks, where A are solvophilic and B are solvophobic and N = 2nm. The conformations are classified in five cases of globule formation by the solvophobic blocks of the chain. The dependence of globule characteristics on the molecular weight and on the number of blocks, which participate in their formation, is examined. The focus is on relative high molecular weight blocks (i.e., N in the range of 500–5000 units) and very differing energetic conditions for the two blocks (very good—almost athermal solvent for A and bad solvent for B). A rich phase behavior is observed as a result of the alternating architecture of the multiblock copolymer chain. We trust that thermodynamic equilibrium has been reached for chains of N up to 2000 units; however, for longer chains kinetic entrapments are observed. The comparison among equivalent globules consisting of different number of B-blocks shows that the more the solvophobic blocks constituting the globule the bigger its radius of gyration and the looser its structure. Comparisons between globules formed by the solvophobic blocks of the multiblock copolymer chain and their homopolymer analogs highlight the important role of the solvophilic A-blocks.

  11. Formation of Nonclassical Ordered Phases of A B -Type Multiarm Block Copolymers

    Science.gov (United States)

    Gao, Ya; Deng, Hanlin; Li, Weihua; Qiu, Feng; Shi, An-Chang

    2016-02-01

    The formation of ordered phases from block copolymers is driven by a delicate balance between the monomer-monomer interaction and chain configurational entropy. The configurational entropy can be regulated by designed chain architecture, resulting in a new entropy-driven mechanism to control the self-assembly of ordered phases from block copolymers. An effective routine to regulate the configurational entropy is to utilize multiarm architecture, in which the entropic contribution to the free energy could be qualitatively controlled by the fraction of bridging configurations. As an illustration of this mechanism, the phase behavior of two A B -type multiarm block copolymers, B0-(Bi-Ai) m and (B1-Ai-B2) m where the minority A blocks form cylindrical or spherical domains, are examined using the self-consistent field theory (SCFT). The SCFT results demonstrate that the packing symmetry of the cylinders or spheres can be controlled by the length of the bridging B blocks. Several nonclassical ordered phases, including a novel square array cylinder with p 4 m m symmetry, are predicted to form from the A B -type multiarm block copolymers.

  12. Micelles, Lamellaes and Connected Bilayer Membranes in Block Copolymer Melts, Blends and Solutions

    Science.gov (United States)

    Mortensen, Kell

    1997-03-01

    Block copolymers of poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, provide a unique model system for studies of aqueous systems of amphilic macromolecules, as the amphiphilic character can be changed continuously by changing temperature(K Mortensen, W Brown, B. Nordén , Phys. Rev. Letters 13 2340 (1992)) or pressure(K Mortensen, D Schwahn S Janssen Phys. Rev. Letters 71 1728 (1993)). The structural characteristics of aqueous solutions of the PEO-PPO-PEO copolymers and their self-associated assemblies are reviewed(K Mortensen, J. Phys. Cond. Matter 8 A103 (1996)). It is shown by small-angle neutron scattering that at low temperatures and/or concentration the individual copolymers exist in solution as individual unimers. Depending on molecular design, i.e. size of the individual blocks, various aggregates are formed, including spherical, worm-like and disc-shaped micelles. The spherical micelles provide the basis for liquid-crystalline mesophases of cubic structure. The crystallization can be understood as a simple hard-sphere condensation. Worm- or rod-like micelles may form nematic or hexagonally ordered structures, whereas the discs may condense into lamellar phases. While bi-continuous microemulsions frequently appear in ternary phase diagrams of oil, water and low-molecular surfactants, there has only recently been observations of such phases in binary systems of block copolymers and solvent. The first observation was made in an aqueous solution of a low PEO-content PEO-PPO-PEO triblock copolymer(E Hecht, K Mortensen, H Hoffmann, Macromolecules 28 5465, 1995). More recently, the microemulsion sponge phase has been observed in a system of tri-block copolymers dissolved in homopolymers( JH Laurer, JC Fung, JW Sedat, DA Agard, SD Schmit, J Samseth, K Mortensen, RJ Spontak, Langmuir, submitted) and in a ternary systems of diblock copolymer and homopolymers(FS Bates, WW Maurer, PM Lipic MA Hillmyer, KA Almdal, K Mortensen, TP Lodge Science, submitted).

  13. Synthesis of Dextran/Methoxy Poly(ethylene glycol) Block Copolymer

    OpenAIRE

    Young-Il Jeong; Dong-Gon Kim; Dae-Hwan Kang

    2013-01-01

    We synthesized a block copolymer composed of dextran and methoxy poly(ethylene glycol) (mPEG). To accomplish this, the end group of dextran was modified by reductive amination. The aminated dextran (Dextran-NH2) showed the intrinsic peaks of both dextran at 3~5.5 ppm and hexamethylene diamine at 1~2.6 ppm at 1H nuclear magnetic resonance (NMR) spectrum. The amino end group of dextran was conjugated with mPEG to make the block copolymer consisting of dextran/mPEG (abbre...

  14. ADVANCES IN MICROEMULSION PHASE ON SELF-ASSEMBLY AND MICELLE EXTRACTION WITH BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Chen Guo; Hao Wen; Huizhou Liu

    2005-01-01

    In this paper we review our work on self-assembly of the system, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, which is a kind of macromolecular complex fluids. The control of self-assembly could be obtained by adding inorganic salts or aliphatic alcohols. By self-assembly of amphiphilic block copolymers, a microemulsion phase is formed, which could be applied in micelle extraction, such as hollow-fiber membrane micelle extraction, magnetic micelle extraction and immobilized micelle extraction.

  15. Data on macrophage mediated muscle transfection upon delivery of naked plasmid DNA with block copolymers.

    Science.gov (United States)

    Mahajan, Vivek; Gaymalov, Zagit; Alakhova, Daria; Gupta, Richa; Zucker, Irving H; Kabanov, Alexander V

    2016-06-01

    The data contains 14 figures supporting the research article "Horizontal gene transfer from macrophages to ischemic muscles upon delivery of naked DNA with Pluronic block copolymers" [1]. The data explains the surgical procedure and histological characterization of Murine Hind Limb Ischemia. The data also shows the kinetics of luciferase gene expression, spread of GFP expression through muscle and the colocalization of GFP with cellular markers in ischemic muscles injected with pDNA alone or pDNA/Pluronic. Finally the data shows the effect of Pluronic Block Copolymer to enhance total gene expression (cmv-promoter driven luciferase gene) in coculture of DNA transfected MØs with muscle cells. PMID:27222845

  16. Azidated Ether-Butadiene-Ether Block Copolymers as Binders for Solid Propellants

    Science.gov (United States)

    Cappello, Miriam; Lamia, Pietro; Mura, Claudio; Polacco, Giovanni; Filippi, Sara

    2016-07-01

    Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene-polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.

  17. Flow-directed block copolymer micelle morphologies via microfluidic self-assembly.

    Science.gov (United States)

    Wang, Chih-Wei; Sinton, David; Moffitt, Matthew G

    2011-11-23

    The self-assembly of amphiphilic block copolymers in a gas-liquid microfluidic reactor produces variable, flow-directed micellar morphologies entirely different from off-chip equilibrium structures. A polystyrene-block-poly(acrylic acid) copolymer, which forms exclusively spheres off-chip, generates kinetic cylinders, Y-junctions, bilayers, and networks by a mechanism of collision-coalescence enabled by strong and localized on-chip shear fields. Variation in the size and relative amount of flow-directed nanostructures is achieved by changing the water content and flow rate. These results demonstrate on-chip processing routes to specific functional colloidal nanostructures. PMID:21992654

  18. Enhancing relative permittivity by incorporating PDMS-PEG multi block copolymers in binary polymer blends

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts a possibil......Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts a...

  19. Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

    International Nuclear Information System (INIS)

    Microphase-separated structures of copolymers with various architectures and their polymer/polymer interfaces were studied. They are SP diblock, PSP triblock, and SPP graft copolymers, where S and P denote polystyrene and poly(2-vinylpyridine), respectively. Morphological observations were carried out by means of transmission electron microscopy and small-angle X-ray scattering. Chain dimensions of component polymers were measured by small-angle neutron scattering and microphase-separated interfaces were observed by neutron reflectivity measurements using deuterium-labeled samples. It was clarified that morphological phase transitions among thermodynamically equilibrium structures for SP diblock and PSP triblock copolymers occur at almost the same compositions; however, those of SPP graft copolymers tend to occur at higher volume fraction of polystyrene, φs, than those for block copolymers. As for alternating lamellar structures it turned out to be clear that lamellar domain spacings, D's, were scaled as the 2/3 power of the molecular weight of polymers irrespective of their architectures. S block chains of SP diblock and PSP triblock copolymers in lamellar structures were both confirmed to be deformed toward the direction perpendicular to the lamellar interfaces, but it revealed that their volumes were preserved. Further, S/P interfacial thicknesses of SP and PSP were essentially the same to each other and the values defined as the FWHM of the error functions which express the segment density distributions of the interfaces were determined to be about 4 nm. (author)

  20. High-strain-induced deformation mechanisms in block-graft and multigraft copolymers

    KAUST Repository

    Schlegel, Ralf

    2011-12-13

    The molecular orientation behavior and structural changes of morphology at high strains for multigraft and block-graft copolymers based on polystyrene (PS) and polyisoprene (PI) were investigated during uniaxial monotonic loading via FT-IR and synchrotron SAXS. Results from FT-IR revealed specific orientations of PS and PI segments depending on molecular architecture and on the morphology, while structural investigations revealed a typical decrease in long-range order with increasing strain. This decrease was interpreted as strain-induced dissolution of the glassy blocks in the soft matrix, which is assumed to affect an additional enthalpic contribution (strain-induced mixing of polymer chains) and stronger retracting forces of the network chains during elongation. Our interpretation is supported by FT-IR measurements showing similar orientation of rubbery and glassy segments up to high strains. It also points to highly deformable PS domains. By synchrotron SAXS, we observed in the neo-Hookean region an approach of glassy domains, while at higher elongations the intensity of the primary reflection peak was significantly decreasing. The latter clearly verifies the assumption that the glassy chains are pulled out from the domains and are partly mixed in the PI matrix. Results obtained by applying models of rubber elasticity to stress-strain and hysteresis data revealed similar correlations between the softening behavior and molecular and morphological parameters. Further, an influence of the network modality was observed (random grafted branches). For sphere forming multigraft copolymers the domain functionality was found to be less important to achieve improved mechanical properties but rather size and distribution of the domains. © 2011 American Chemical Society.

  1. Analysis of the aggregation structure from amphiphilic block copolymers in solutions by small-angle x-ray scattering

    CERN Document Server

    Rong Li Xia; Wang Jun; Wei Liu He; Li Fu Mian; Li Zi Chen

    2002-01-01

    The aggregation structure of polystyrene-p vinyl benzoic amphiphilic block copolymers which were prepared in different conditions was investigated by synchrotron radiation small-angle x-ray scattering (SAXS). The micelle was self-assembled in selective solvents of the block copolymers. Authors' results demonstrate that the structure of the micelle depends on the factors, such as the composition of the copolymers, the nature of the solvent and the concentration of the solution

  2. Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

    OpenAIRE

    Fatime Eren Erol; Deniz Sinirlioglu; Sedat Cosgun; Ali Ekrem Muftuoglu

    2014-01-01

    Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP) and Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA) random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-M...

  3. Characterization of high performance randomly segmented poly(urethane siloxane) and poly(imide siloxane) block copolymers

    Science.gov (United States)

    Doǧan, Türkan; Baydoǧan, Nilgün; Köken, Nesrin

    2016-03-01

    Poly(imide siloxane) block copolymers with the same polydimethlysiloxane(APPS) were prepared by using 4,4'-oxydianiline (ODA) and Benzofenon-3,3,4,4-tetrakarboksilik dianhydride(BTDA) to compose the polyimide hard block. APPS and BTDA composed the polysiloxane soft block. The length of polysiloxane soft blocks increased with increasing the length of polyimide hard block. Copolymerization of soft and hard segments were determined by using this method. Copolymer structures could be obtained by holding constant hard block segments and by adjusting and increasing soft block segments. Thus, more flexible randomly segmented poly(imide siloxane) block copolymers can be obtained. These composed structure as flexible and high performance copolymers were characterized by FT-IR and evaluated. The structures were tested mechanically to detect their elastic recovery property as flexible material. The characterization of the samples enabled to examine flexible substrates in order to use in solar cell, aerospace applications and microelectronic devices.

  4. A simple pathway to ordered silica nanopattern from self-assembling of block copolymer containing organic silicon block

    International Nuclear Information System (INIS)

    Self-assembly of block copolymer is an effective strategy to prepare periodic structures at nanoscale. In this paper an unique and very simple method to prepare inorganic silica nanopattern is demonstrated from self-assembling of poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) on the surface of silicon wafer. To simplify the patterning process, at first we obtain highly ordered PDMS microdomains, which are covered with PS layer by controlling solvent vapor annealing conditions. Following exposure to UV/O3 irradiation, nanopatterned surface consisting of silicon oxide is fabricated directly via selectively etching PS phase and converting PDMS phase into silicon oxide. As tuning the composition of the block copolymer, hexagonally packing dot and straight stripe pattern can be obtained. Finally, the time evolution from spheres morphology to aligned long cylinders is discussed. These results hold promise for nanolithography and the fabrication of nanodevices.

  5. Topcoat approaches for directed-assembly of copolymer films with blocks exhibiting differences in surface energy

    Science.gov (United States)

    Suh, Hyo Seon; in Lee, Jeong; Ramirez-Hernandez, Abelardo; Tada, Yasuhiko; Yoshida, Hiroshi; Wan, Lei; Ruiz, Ricardo; de Pablo, Juan; Nealey, Paul

    2013-03-01

    Fabricating patterns with feature dimensions smaller than 10 nm scale using block copolymer lithography requires the use of materials with large Flory-Huggins interaction parameters. Because such block copolymers (BCPs) typically show the large differences in surface energy between the blocks, one block (with lower surface energy) tends to segregate to the free surface of films and precludes the assembly of the desired through-film perpendicularly oriented structures. Here we describe a generalizable strategy to overcome this limitation. By coating the BCP film with an additional layer, a topcoat, thermodynamically favorable boundary conditions at the top surface of the film can be engineered for directed self-assembly. The allowable properties of the topcoats depend on the interfacial energies of the layer with the blocks of the copolymer, and the block-block interfacial energy. The strategy is demonstrated experimentally by directing the assembly of polystyrene-block-poly-2-vinylpyridine (PS- b-P2VP) films on chemically nanopatterned substrates with different topcoat materials.

  6. Living cationic polymerization and polyhomologation: an ideal combination to synthesize functionalized polyethylene–polyisobutylene block copolymers

    KAUST Repository

    Zhang, Hefeng

    2015-12-17

    A series of hydroxyl-terminated polyisobutylene-b-polyethylene (PIB-b-PE-OH) copolymers were synthesized by combining living cationic polymerization and polyhomologation. Allyl-terminated PIBs, synthesized by living cationic polymerization, were hydroborated with BH3·THF to produce 3-arm boron-linked stars, PIB3B, which served as macroinitiators for the in situ polyhomologation of dimethylsulfoxonium methylide. The resulting 3-arm star block copolymers, (PIB-b-PE)3B, were oxidized/hydrolysed to afford PIB-b-PE-OH. Characterization of all intermediates and final products by high temperature gel permeation chromatography (HT-GPC) and proton nuclear magnetic resonance spectroscopy (1H NMR) revealed the well-defined character of the copolymers. The thermal properties of the copolymers were studied by differential scanning calorimetry (DSC).

  7. Self-assembled structures of amphiphilic ionic block copolymers: Theory, self-consistent field modeling and experiment

    NARCIS (Netherlands)

    Borisov, O.V.; Zhulina, E.B.; Leermakers, F.A.M.; Muller, A.H.E.

    2011-01-01

    We present an overview of statistical thermodynamic theories that describe the self-assembly of amphiphilic ionic/hydrophobic diblock copolymers in dilute solution. Block copolymers with both strongly and weakly dissociating (pH-sensitive) ionic blocks are considered. We focus mostly on structural a

  8. Structure-property relationships in multilayered polymeric system and olefinic block copolymers

    Science.gov (United States)

    Khariwala, Devang

    Chapter 1. The effect of tie-layer thickness on delamination behavior of polypropylene/tie-layer/Nylon-6 multilayers is examined in this study. Various maleated polypropylene resins were compared for their effectiveness as tie-layers. Delamination failure occurred cohesively in all the multilayer systems. Two adhesion regimes were defined based on the change in slope of the linear relationship between the delamination toughness and the tie-layer thickness. The measured delamination toughness of the various tie-layers was quantitatively correlated to the damage zone length formed at the crack tip. In addition, the effect of tie-layer thickness on the multilayer tensile properties was correlated with the delamination behavior. The fracture strain of the multilayers decreased with decreasing tie-layer thickness. Examination of the prefracture damage mechanism of stretched multilayers revealed good correlation with the delamination toughness of the tie-layers. In thick tie-layers (>2microm) the delamination toughness of the tie-layers was large enough to prevent delamination of multilayers when they were stretched. In the thin tie-layers (block copolymers with properties typical of thermoplastic elastomers. The block copolymers synthesized by chain shuttling technology consist of crystallizable ethylene-octene blocks with low comonomer content and high melting temperature (hard blocks), alternating with amorphous ethylene-octene blocks with high comonomer content and low glass transition temperature (soft blocks). This study describes the material science of these unique polymers as characterized by thermal analysis, X-ray diffraction, microscopy, and tensile deformation. The crystallizable blocks are long enough to form well-organized lamellar crystals with the orthorhombic unit cell and high melting temperature. The lamellae are organized into space-filling spherulites in all compositions even in copolymers with only 18 wt% hard block. The morphology is consistent

  9. Enantiomeric PLA-PEG block copolymers and their stereocomplex micelles used as rifampin delivery

    International Nuclear Information System (INIS)

    A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA-PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA-PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly(l-lactide)-poly(ethylene-glycol) (PLLA-PEG) and poly(D-lactide)-poly(ethylene-glycol) (PDLA-PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA-PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8-4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer. Compared with the single PLLA-PEG or PDLA-PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and the morphology of the polymer micelles

  10. PS-b-PDMS Block Copolymer Thin Film: Pattern Formation and Phase Behavior

    Science.gov (United States)

    Hsieh, I.-Fan; Cheng, Stephen Z. D.; Department of Polymer Science, The University of Akron Team

    2011-03-01

    Recently, block copolymer thin films attract great attention due to their potential applications in surface nano-lithography. In our work, PS- b -PDMS with cylinder morphology is chosen due to extremely large χ value between two blocks. Besides, PS- b -PDMS can be transformed into silicon oxide under UV/O3 exposure and a layer of silicon oxide with the self-assembled block copolymer patterns can be made. By utilizing the PGMEA as solvent, we can easily obtain sphere morphology in cylindrical composition block copolymer by preserved block copolymer solution morphology during film formation. Furthermore, in thermal annealing process, the phase behavior of the PS- b -PDMS thin film is strongly affects by molecular weight, film thickness and annealing temperature. In larger-molecular-weight PS- b -PDMS, we only observed spherical domains rearrangement and without morphology transition between sphere and cylinder due to high energy barrier, whereas, in the case of smaller-molecular-weight polymer, depending on the film thickness and annealing temperature, its thin film morphology transits between sphere and cylinder alternatively, which is similar to what we found in solvent annealing.

  11. Block copolymer modified surfaces for conjugation of biomacromolecules with control of quantity and activity.

    Science.gov (United States)

    Li, Xin; Wang, Mengmeng; Wang, Lei; Shi, Xiujuan; Xu, Yajun; Song, Bo; Chen, Hong

    2013-01-29

    Polymer brush layers based on block copolymers of poly(oligo(ethylene glycol) methacrylate) (POEGMA) and poly(glycidyl methacrylate) (PGMA) were formed on silicon wafers by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). Different types of biomolecule can be conjugated to these brush layers by reaction of PGMA epoxide groups with amino groups in the biomolecule, while POEGMA, which resists nonspecific protein adsorption, provides an antifouling environment. Surfaces were characterized by water contact angle, ellipsometry, and Fourier transform infrared spectroscopy (FTIR) to confirm the modification reactions. Phase segregation of the copolymer blocks in the layers was observed by AFM. The effect of surface properties on protein conjugation was investigated using radiolabeling methods. It was shown that surfaces with POEGMA layers were protein resistant, while the quantity of protein conjugated to the diblock copolymer modified surfaces increased with increasing PGMA layer thickness. The activity of lysozyme conjugated on the surface could also be controlled by varying the thickness of the copolymer layer. When biotin was conjugated to the block copolymer grafts, the surface remained resistant to nonspecific protein adsorption but showed specific binding of avidin. These properties, that is, well-controlled quantity and activity of conjugated biomolecules and specificity of interaction with target biomolecules may be exploited for the improvement of signal-to-noise ratio in sensor applications. More generally, such surfaces may be useful as biological recognition elements of high specificity for functional biomaterials. PMID:23265296

  12. Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides

    Science.gov (United States)

    Görl, Daniel; Zhang, Xin; Stepanenko, Vladimir; Würthner, Frank

    2015-05-01

    New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.

  13. Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

    Directory of Open Access Journals (Sweden)

    Hyang Moo Lee

    2016-03-01

    Full Text Available Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG, poly(2,2,2-trifluoroethyl methacrylate-block-poly(4-vinyl pyridine (PTFEMA-b-PVP block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT polymerization and used as polymeric dispersants in liquid phase exfoliation assisted by ultrasonication. The HOPG graphene concentrations were found to be 0.260–0.385 mg/mL in methanolic graphene dispersions stabilized with 10 wt % (relative to HOPG PTFEMA-b-PVP block copolymers after one week. Raman and atomic force microscopy (AFM analyses revealed that HOPG could not be completely exfoliated during the sonication. However, on-line turbidity results confirmed that the dispersion stability of HOPG in the presence of the block copolymer lasted for one week and that longer PTFEMA and PVP blocks led to better graphene dispersibility. Force–distance (F–d analyses of AFM showed that PVP block is a good graphene-philic block while PTFEMA is methanol-philic.

  14. Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon Jeong; Nedoma, Alisyn J.; Geissler, Phillip L.; Balsara, Nitash P.; Jackson, Andrew; Cookson, David (UCB); (NIST); (Aust. Synch.); (LBNL)

    2008-08-21

    The phase behavior of ion-containing block copolymer membranes in equilibrium with humidified air is studied as a function of the relative humidity (RH) of the surrounding air, ion content of the copolymer, and temperature. Increasing RH at constant temperature results in both disorder-to-order and order-to-order transitions. In-situ small-angle neutron scattering experiments on the open block copolymer system, when combined with water uptake measurement, indicate that the disorder-to-order transition is driven by an increase in the partial molar entropy of the water molecules in the ordered phase relative to that in the disordered phase. This is in contrast to most systems wherein increasing entropy results in stabilization of the disordered phase.

  15. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration

    KAUST Repository

    Yu, Haizhou

    2015-09-21

    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol−1 in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux.

  16. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration.

    Science.gov (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Moreno, Nicolas; Ma, Zengwei; Calo, Victor Manuel; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2015-11-16

    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol(-1) in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux. PMID:26388216

  17. Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

    Science.gov (United States)

    Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

    2016-09-15

    Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. PMID:27309943

  18. Synthesis of tri-block copolymers through reverse atom transfer radical polymerization of methyl methacrylate using polyurethane macroiniferter

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available Reverse atom transfer radical polymerization was successfully used for the first time to synthesis tri-block copolymers. Poly (methyl methacrylate-block-polyurethane-block-poly (methyl methacrylate tri-block copolymers were synthesized using tetraphenylethane-based polyurethane as a macroiniferter, copper(II halide as a catalyst and N, N, N′, N″, N″-pentamethyldiethylenetriamine as a ligand. Controlled nature of the polymerization was confirmed by the linear increase of number average molecular weight with increasing conversion. Mole contents of poly (methyl methacrylate present in the tri-block copolymers were calculated using proton nuclear magnetic resonance spectroscopy and the results were comparable with the gel permeation chromatography results. Differential scanning calorimetric results confirmed the presence of two different types of blocks in the tri-block copolymers.

  19. Block Copolymer Electrolytes: Thermodynamics, Ion Transport, and Use in Solid- State Lithium/Sulfur Cells

    Science.gov (United States)

    Teran, Alexander Andrew

    Nanostructured block copolymer electrolytes containing an ion-conducting block and a modulus-strengthening block are of interest for applications in solid-state lithium metal batteries. These materials can self-assemble into well-defined microstructures, creating conducting channels that facilitate ion transport. The overall objective of this dissertation is to gain a better understanding of the behavior of salt-containing block copolymers, and evaluate their potential for use in solid-state lithium/sulfur batteries. Anionically synthesized polystyrene-b-poly(ethylene oxide) (SEO) copolymers doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt were used as a model system. This thesis investigates the model system on several levels: from fundamental thermodynamic studies to bulk characterization and finally device assembly and testing. First, the thermodynamics of neat and salt-containing block copolymers was studied. The addition of salt to these materials is necessary to make them conductive, however even small amounts of salt can have significant effects on their phase behavior, and consequently their iontransport and mechanical properties. As a result, the effect of salt addition on block copolymer thermodynamics has been the subject of significant interest over the last decade. A comprehensive study of the thermodynamics of block copolymer/salt mixtures over a wide range of molecular weights, compositions, salt concentrations and temperatures was conducted. Next, the effect of molecular weight on ion transport in both homopolymer and copolymer electrolytes were studied over a wide range of chain lengths. Homopolymer electrolytes show an inverse relationship between conductivity and chain length, with a plateau in the infinite molecular weight limit. This is due to the presence of two mechanisms of ion conduction in homopolymers; the first mechanism is a result of the segmental motion of the chains surrounding the salt ions, 2 creating a liquid

  20. SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Zi-fa Li; Shu-yuan Zhang; Shao-kui Cao; Ming-sheng Tang; Qiu-jun Fen; Qi-feng Zhou

    1999-01-01

    A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC,DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase when they were heated to their melting temperatures (Tm) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperaturevariable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.

  1. Synthesis of (meth)acrylate block copolymers by ligated anionic polymerization

    Czech Academy of Sciences Publication Activity Database

    Vlček, Petr; Čadová, Eva; Janata, Miroslav; Látalová, Petra; Toman, Luděk; Kříž, Jaroslav; Kurková, Dana

    Goa : International Union of Pure and Applied Chemistry, 2005. s. 20-21. [International Symposium on Ionic Polymerization. 23.10.2005-28.10.2005, Goa ] R&D Projects: GA MŠk 1P05ME753 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymers * anionic polymerization * tert-alkoxides Subject RIV: CD - Macromolecular Chemistry

  2. Complexes of block copolymers in solution: a graph-theoretical approach

    NARCIS (Netherlands)

    Damme, van Ruud; Geurts, Bernard J.

    1989-01-01

    We determine the statistical properties of block copolymers in solution. These complexes are assumed to have the topological structure of connected graphs with “nonnested” loops and cycles. The generating function method is used to determine the number of topologically different complexes containing

  3. Biodegradable block-copolymer micelles:Synthesis, characterization and radiolabelling for biodistribution studies

    Czech Academy of Sciences Publication Activity Database

    Machová, Luďka; Malinova, V.; Nováková, K.; Lázníček, M.; Koňák, Čestmír; Rypáček, František

    Antalya : Ankara University, Tissue Engineering and Biomaterials Laboratory, 2002. s. P-36. [International Symposium on Biomedical Science and Technology BIOMED /9./. 19.09.2002-22.09.2002, Antalya ] R&D Projects: GA AV ČR IAA4050202 Keywords : amphiphilic block copolymers * micelle * PLA-PEO Subject RIV: CD - Macromolecular Chemistry

  4. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    NARCIS (Netherlands)

    Grainger, D.W.; Kim, S.W.; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable

  5. Interfacial activity of styrene-butadiene block copolymers in low-density polyethylene/polystyrene blends

    Czech Academy of Sciences Publication Activity Database

    Fortelný, Ivan; Šlouf, Miroslav; Hlavatá, Drahomíra; Sikora, Antonín

    2006-01-01

    Roč. 13, 8-9 (2006), s. 783-799. ISSN 0927-6440 Institutional research plan: CEZ:AV0Z40500505 Keywords : compatibilization * polymer blends * block copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.788, year: 2006

  6. Thin block copolymer films : film formation and corrugation under the AFM tip

    NARCIS (Netherlands)

    Maas, J.H.; Cohen Stuart, M.A.; Fleer, G.J.

    2000-01-01

    The tip of an atomic force microscope was used to induce nanoscale ordering in thin films of polystyrene-poly(4-vinyl pyridine) block copolymers under low force. The AFM tip produces rims on a mesoscopic scale oriented perpendicularly to the scanning direction. A wide range of molecular weights of b

  7. LEO resistant PI-B-PDMS block copolymer films for solar array applications

    NARCIS (Netherlands)

    Lonkhuyzen, H. van; Bongers, E.; Fischer, H.R.; Dingemans, T.J.; Semprimoschnig, C.

    2013-01-01

    Due to their low atomic oxygen erosion yields PI-b-PDMS block copolymer films have considerable potential for application onto space exposed surfaces of satellites in low earth orbit. On solar arrays these materials might be used as electrical electrical insulation film, flexprint outer layer, elect

  8. Water vapor and gas transport through a poly (butylene terephthalate) poly (ethylene oxide) block copolymer

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, J.; Mulder, M.H.V.; Wessling, M.

    2002-01-01

    In this paper the transport behavior of water vapor and nitrogen in a poly(butylene terephthalate) poly (ethylene oxide) block copolymer is discussed. This polymer has a high solubility for water (300 cm3 (STP)/cm3 polymer at activity 0.9). A new permeation set up has been built to determine the wat

  9. Self-assembled Block Copolymers with Various Architectures Designed by ATRP

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja

    networks and demonstrate good Li+ complexation and conductivity. These make the materials a potential for solid electrolyte applications in Li+ ion batteries (4, 6). iii. Amphiphilic water soluble star block copolymers with a polyacrylic acid core form hydrogels at room temperature above concentration 22g...

  10. Synthesis of Dendritic-Linear Block Copolymers by Atom Transfer Radical Polymerization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dendritic polyarylether 2-bromoisobutyrate as the macromolecular initiator for the controlled free radical polymerization of styrene was investigated. The polymerization was carried out with CuBr/2,2′-bipyridine catalyst at 110℃. It is found that the hybrid dendritic-linear block copolymers possess well-defined molecular weights and low polydispersities.

  11. Self-assembly of POSS-containing block copolymers: fixing the hierarchical structure in networks

    Czech Academy of Sciences Publication Activity Database

    Matějka, Libor; Janata, Miroslav; Pleštil, Josef; Zhigunov, Alexander; Šlouf, Miroslav

    2014-01-01

    Roč. 55, č. 1 (2014), s. 126-136. ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Grant ostatní: AV ČR(CZ) M200500903 Institutional support: RVO:61389013 Keywords : block copolymers * self-assembly * POSS Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

  12. Effect of Electric Field Alignment on Morphology and Ionic Conductivity of Polymerized Ionic Liquid Block Copolymers

    Science.gov (United States)

    Sharick, Sharon; Nykaza, Jacob; Elabd, Yossef A.; Winey, Karen I.

    2014-03-01

    Polymerized ionic liquid (PIL) block copolymers are appealing for numerous electrochemical applications, including solid polymer electrolyte membranes for batteries and anion exchange membranes for fuel cells. The extent to which the reduced segmental motion caused by the non-conducting polymer segments and grain boundaries between block copolymer microdomains are detrimental to ionic conductivity is unknown. Increased long-range morphological order and connectivity of PIL microdomains are key to understanding the ion transport mechanism and may improve the ionic conductivity of PIL block copolymers. The effect of electric field on the morphology and ionic conductivity of poly(styrene- b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-bis(trifluoromethanesulfonyl)imide)) (PS- b-PMEBIm-TFSI) will be discussed as a function of microdomain orientation. Electric field is used to increase the perpendicular orientation of ion-conducting pathways with respect to the electrodes. The morphology and ionic conductivity were characterized by small-angle X-ray scattering and electrochemical impedance spectroscopy, respectively. The ionic conductivity of unoriented and oriented block copolymers will be compared to the PIL homopolymer, PMEBIm-TFSI, using the Sax and Ottino model.

  13. DYNAMIC DENSITY-FUNCTIONAL THEORY FOR MICROPHASE SEPARATION KINETICS OF BLOCK-COPOLYMER MELTS

    NARCIS (Netherlands)

    FRAAIJE, JGEM

    1993-01-01

    In this paper, we describe a numerical method for the calculation of collective diffusion relaxation mechanisms in quenched block copolymer melts. The method entails the repeated calculation of two opposing fields-an external potential field U, conjugate to the density field rho, and an energetic in

  14. Compartmentalization in hybrid metallacarborane nanoparticles formed by block copolymers with star-like architecture

    Czech Academy of Sciences Publication Activity Database

    Ďorďovič, V.; Uchman, M.; Zhigunov, Alexander; Nykänen, A.; Ruokolainen, J.; Matějíček, P.

    2014-01-01

    Roč. 3, č. 11 (2014), s. 1151-1155. ISSN 2161-1653 R&D Projects: GA ČR(CZ) GA14-14608S Institutional support: RVO:61389013 Keywords : nanoparticles * block copolymers * star-like architecture Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.764, year: 2014

  15. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira

    2013-09-24

    Order and porosity of block copolymer membranes have been controlled by solution thermodynamics, self-assembly, and macrophase separation. We have demonstrated how the film manufacture with long-range order can be up-scaled with the use of conventional membrane production technology.

  16. Multiscale Control of Hierarchical Structure in Crystalline Block Copolymer Nanoparticles Using Microfluidics.

    Science.gov (United States)

    Bains, Aman; Cao, Yimeng; Moffitt, Matthew G

    2015-11-01

    Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas-liquid microfluidic reactor with top-down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates. PMID:26305569

  17. Block copolymer self-assembly and co-assembly : shape function and application

    NARCIS (Netherlands)

    Li, F.

    2009-01-01

    Amphiphilic block copolymers can, in selective solvents such as water, assemble into various shapes and architectures. Among those, polymer vesicles, polymer micelles and polymer fibers are very popular structures in current nanotechnology. These objects each have their own particular properties and

  18. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  19. Star block-copolymers: Enzyme-inspired catalysts for oxidation of alcohols in water

    KAUST Repository

    Mugemana, Clement

    2014-01-01

    A number of fluorous amphiphilic star block-copolymers containing a tris(benzyltriazolylmethyl)amine motif have been prepared. These polymers assembled into well-defined nanostructures in water, and their mode of assembly could be controlled by changing the composition of the polymer. The polymers were used for enzyme-inspired catalysis of alcohol oxidation. This journal is © the Partner Organisations 2014.

  20. Lamellar Microdomains of Block-Copolymer-Based Ionic Supramolecules Exhibiting a Hierarchical Self-Assembly

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Almdal, Kristoffer; Zhu, Kaizheng;

    2014-01-01

    Based on a parent diblock copolymer of poly(styrene)-b-poly(methacrylic acid), PS-b-PMAA, linear-b-amphiphilic comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] are synthesized in which the poly(methacrylate) backbone of the ionic supramolecular AC-block is neutralized by alkyl...

  1. Composition and solution properties of fluorinated block copolymers and their surface structures in the solid state

    Institute of Scientific and Technical Information of China (English)

    NI HuaGang; XUE DongWu; WANG XiaoFang; ZHANG Wei; WANG XinPing; SHEN ZhiQuan

    2009-01-01

    A series of diblock copolymers composed of methyl methacrylate and 2-perfluorooctylethyl methacry-late (PMMA144-b-PFMAn) with various PFMA block lengths were prepared by atom transfer radical po-lymerization (ATRP). The surface structures and properties of these polymers in the solid state and in solution were investigated using contact angle measurement, X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, surface tension and dynamic laser light scattering (DLS). It was found that with increasing PFMA block length, water and oil repellency de-creased, the ratio of F/C increased with increasing film depth, and the degree of ordered packing of the perfluoroalkyl side chains at the surface decreased. When the number of PFMA block units reached 10, PMMA segments were detected at the copolymer surface, which was attributed to the PFMA block length affecting molecular aggregation structure of the copolymer in the solution and the interfacial structure at the air/liquid interface, which in turn affects surface structure formation during solution solidification. The results suggest that copolymer solution properties play an important role in struc-ture formation on the solid surface.

  2. Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Li, Tao; Wu, Kaiyu; Rindzevicius, Tomas;

    2016-01-01

    ). Direct silicon etching with high aspect ratio templated by the block copolymer mask is realized without any intermediate layer or external precursors. Uniquely, an atomic layer deposition (ALD)-assisted method is introduced to allow reversing of the morphology relative to the initial pattern. As a result...

  3. Modification of polylactide surfaces with PLA-b-PEO block copolymers deposited from selective solvents

    Czech Academy of Sciences Publication Activity Database

    Chánová, Eliška; Popelka, Štěpán; Machová, Luďka; Rypáček, František

    New Rochelle: Mary Ann Liebert, Inc, 2008. s. 881 R&D Projects: GA MŠk 1M0538; GA AV ČR(CZ) 1QS500110564 EU Projects: European Commission(XE) 500283 - EXPERTISSUES Institutional research pla n: CEZ:AV0Z40500505 Keywords : amphiphilic block copolymers * polylactide * drug delivery systems Subject RIV: CD - Macromolecular Chemistry

  4. Asymmetrical Self-assembly From Fluorinated and Sulfonated Block Copolymers in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun [ORNL; Hong, Kunlun [ORNL; Baskaran, Durairaj [University of Tennessee, Knoxville (UTK); Goswami, Monojoy [ORNL; Sumpter, Bobby G [ORNL; Mays, Jimmy [ORNL

    2011-01-01

    Block copolymers of fluorinated isoprene and partially sulfonated styrene form novel tapered rods and ribbon-like micelles in aqueous media due to a distribution of sulfonation sites and a large Flory-Huggins interaction parameter. A combination of microscopy, light scattering, and simulation demonstrates the presence of these unique nanostructures. This study sheds light on the micellization behavior of amphiphilic block polymers by revealing a new mechanism of self-assembly.

  5. Morphology-controlled growth of perylene derivative induced by double-hydrophilic block copolymers

    OpenAIRE

    Minghua Huang; Markus Antonietti; Helmut Cölfen

    2016-01-01

    Controlled growth of technically relevant perylene derivative 3, 4, 9, 10-perylenetetracarboxylic acid potassium salt (PTCAPS), with tuneable morpologies, has been successfully realized by a recrystallization method using a double-hydrophilic block copolymer poly (ethylene glycol)-block poly (ethyleneimine) (PEG-b-PEI) as the structure directing agent. The {001} faces of PTCAPS are most polar and adsorb the oppositively charged polymer additive PEG-b-PEI well by electrostatic attraction. By s...

  6. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion

    OpenAIRE

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible add...

  7. Thermally sensitive block copolymer hydrogels in bulk and with decreased dimensions

    OpenAIRE

    Nykänen, Antti

    2013-01-01

    The research on stimuli-responsive polymers has increased rapidly during the last two decades. Poly(N-isopropylacrylamide) (PNIPAM) is one of the most studied thermally responsive polymer because its lower critical solution temperature (LCST) 32 ℃ is close to the ambient conditions. Below 32 ℃, PNIPAM is water soluble, but at temperatures above 32 ℃ the polymer phase separates from water. In this thesis, amphiphilic triblock copolymer polystyrene-block-poly(N-isopropylacrylamide)-block-polys...

  8. Ligand switch in photoinduced copper-mediated polymerization: synthesis of methacrylate-acrylate block copolymers

    OpenAIRE

    CHUANG, Ya-Mi; Wenn, Benjamin; Gielen, Sam; Ethirajan, Anitha; Junkers, Thomas

    2015-01-01

    The use of photo-induced copper-mediated radical polymerization (photoCMP) to synthesize mixed acrylate/methacrylate (methyl acrylate, MA and methyl methacrylate, MMA) block copolymers is investigated. Reactions in which only one type of ligand (Me6TREN) is used lead to unsuccessful outcomes of polymerization due to a mismatch in reactivity of the two monomers. A ligand exchange to PMDETA for methacrylate is required to obtain good block structures. Due to insufficient re-initiation of polyac...

  9. Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

    OpenAIRE

    Hyang Moo Lee; Suguna Perumal; In Woo Cheong

    2016-01-01

    Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG), poly(2,2,2-trifluoroethyl methacrylate)-block-poly(4-vinyl pyridine) (PTFEMA-b-PVP) block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and used as polymeric dispersants in liquid phase exfoliation assiste...

  10. Photoinitiated Crosslinking and Grafting of Methylmethacrylate Using N,N-Dimethyl Amino Functional Polystyrene Block Copolymers

    OpenAIRE

    MÜFTÜOĞLU, Ali Ekrem; YAĞCI, Yusuf; SE, Kazunori

    2004-01-01

    Monodisperse poly(N,N-dimethyl-4-vinylphenethylamine)-block-polystyrene was synthesized via anionic living polymerization carried out at -78 °C under a pressure of 10-6 torr using cumyl potassium as the initiator. Subsequent photoinduced radical polymerization of styrene through side chain-functional N,N-dimethyl amino groups yielded a crosslinked polymer and a brush type block-graft copolymer to a lesser extent. Upon irradiation at a wavelength of 350 nm, macroradicals were generate...

  11. Sub-15nm Silicon Lines Fabrication via PS-b-PDMS Block Copolymer Lithography

    OpenAIRE

    Sozaraj Rasappa; Lars Schulte; Dipu Borah; Morris, Michael A.; Sokol Ndoni

    2013-01-01

    This paper describes the fabrication of nanodimensioned silicon structures on silicon wafers from thin films of a poly(styrene)-block-poly(dimethylsiloxane) (PS-b-PDMS) block copolymer (BCP) precursor self-assembling into cylindrical morphology in the bulk. The structure alignment of the PS-b-PDMS (33 k–17 k) was conditioned by applying solvent and solvothermal annealingtechniques. BCP nanopatterns formed after the annealing process have been confirmed by scanning electron microscope (SEM) af...

  12. Chirality in Block Copolymer Melts: Mesoscopic Helicity from Inter-Segment Twist

    OpenAIRE

    Zhao, Wei; Russell, Thomas P.; Grason, Gregory M.

    2012-01-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly-chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesocopically chiral phase...

  13. Evaluation of Isoprene Chain Extension from PEO Macromolecular Chain Transfer Agents for the Preparation of Dual, Invertible Block Copolymer Nanoassemblies

    OpenAIRE

    Bartels, Jeremy W.; Cauët, Solène I.; Billings, Peter L.; Lin, Lily Yun; Zhu, Jiahua; Fidge, Christopher; Pochan, Darrin J.; Wooley, Karen L.

    2010-01-01

    Two RAFT-capable PEO macro-CTAs, 2 and 5 kDa, were prepared and used for the polymerization of isoprene which yielded well-defined block copolymers of varied lengths and compositions. GPC analysis of the PEO macro-CTAs and block copolymers showed remaining unreacted PEO macro-CTA. Mathematical deconvolution of the GPC chromatograms allowed for the estimation of the blocking efficiency, about 50% for the 5 kDa PEO macro-CTA and 64% for the 2 kDa CTA. Self assembly of the block copolymers in bo...

  14. Phase behavior of ABC-type triple-hydrophilic block copolymers in aqueous solutions.

    Science.gov (United States)

    Zheng, Lingfei; Wu, Jianqi; Wang, Zheng; Yin, Yuhua; Jiang, Run; Li, Baohui

    2016-07-01

    The phase behavior of symmetric ABC triple-hydrophilic triblock copolymers in concentrated aqueous solutions is investigated using a simulated annealing technique. Two typical cases, in which the hydrophilicity of the middle B-block is either stronger or weaker than that of the end A- and C-blocks, are studied. In these two cases, a variety of phase diagrams are constructed as a function of the volume fraction of the B-block and the copolymer concentration ([Formula: see text] for both non-frustrated and frustrated copolymers. Structures, such as two-color alternatingly packed cylinders or gyroid, and lamellae-in-lamellae etc. that do not occur in the melt system, are obtained in solutions. Rich phase transition sequences, especially re-entrant phase transitions involving complex continuous networks of alternating gyroid and alternating diamond are observed for a given copolymer with decreasing [Formula: see text] . The difference in hydrophilicity among different blocks can result in inhomogeneous distribution of solvent molecules in the morphology, and with the decrease of [Formula: see text] , the distribution of solvent molecules presents a non-monotonic variation. This results in a non-monotonic variation of the effective volume fraction of each domain with the decrease of [Formula: see text] , which induces the re-entrant phase transitions. The presence of a good solvent for all the blocks can cause changes in the effective segregation strengths between different blocks and also in chain conformations, hence can alter the bulk phases and results in the occurrence of new structures and phase transitions. Especially, structures having A-C interfaces or A-C mixed domains can be obtained even in the non-frustrated copolymer systems, and structures obtained in the frustrated systems may be similar to those obtained in the non-frustrated systems. The window of the alternating gyroid structures may occupy a large part of the phase diagram for non

  15. Fabrication of periodic arrays of metallic nanoparticles by block copolymer templates on HfO2 substrates.

    Science.gov (United States)

    Frascaroli, Jacopo; Seguini, Gabriele; Spiga, Sabina; Perego, Michele; Boarino, Luca

    2015-05-29

    Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal nanoparticles (NPs) with a diameter down to a few nanometers. In order to develop this technique on metal oxide substrates, we studied the self-assembly of polymeric templates directly on the HfO₂ surface. Using a random copolymer neutralization layer, we obtained an effective HfO₂ surface neutralization, while the effects of surface cleaning and annealing temperature were carefully examined. Varying the block copolymer molecular weight, we produced regular nanoporous templates with feature size variable between 10 and 30 nm and a density up to 1.5 × 10¹¹ cm⁻². With the adoption of a pattern transfer process, we produced ordered arrays of Pt and Pt/Ti NPs with diameters of 12, 21 and 29 nm and a constant size dispersion (σ) of 2.5 nm. For the smallest template adopted, the NP diameter is significantly lower than the original template dimension. In this specific configuration, the granularity of the deposited film probably influences the pattern transfer process and very small NPs of 12 nm were achieved without a significant broadening of the size distribution. PMID:25948389

  16. Time-resolved GISAXS and cryo-microscopy characterization of block copolymer membrane formation

    KAUST Repository

    Marques, Debora S.

    2014-03-01

    Time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and cryo-microscopy were used for the first time to understand the pore evolution by copolymer assembly, leading to the formation of isoporous membranes with exceptional porosity and regularity. The formation of copolymer micelle strings in solution (in DMF/DOX/THF and DMF/DOX) was confirmed by cryo field emission scanning electron microscopy (cryo-FESEM) with a distance of 72 nm between centers of micelles placed in different strings. SAXS measurement of block copolymer solutions in DMF/DOX indicated hexagonal assembly with micelle-to-micelle distance of 84-87 nm for 14-20 wt% copolymer solutions. GISAXS in-plane peaks were detected, revealing order close to hexagonal. The d-spacing corresponding to the first peak in this case was 100-130 nm (lattice constant 115-150 nm) for 17 wt% copolymer solutions evaporating up to 100 s. Time-resolved cryo-FESEM showed the formation of incipient pores on the film surface after 4 s copolymer solution casting with distances between void centers of 125 nm. © 2014 Elsevier Ltd. All rights reserved.

  17. Synthesis and applications of polystyrene-block-poly(N-vinyl-2-pyrrolidone copolymers

    Directory of Open Access Journals (Sweden)

    Marcelo Alexandre de Farias

    2016-02-01

    Full Text Available Abstract This work describes the synthesis and applications of amphiphilic polystyrene-block-poly(N-vinyl-2-pyrrolidone (PS-b-PVP copolymers as a silver and silica nanoparticle surface modification agent. The synthesis of PS-b-PVP was carried out using controlled/living radical polymerization techniques. The synthesis of the block copolymers was confirmed by gel permeation chromatography and hydrogen nuclear magnetic resonance, presenting a polydispersity index of around 1.4 and number average molecular weight ranging between 10,000-14,000 g mol-1. The PS-b-PVP copolymers were applied as a silver nanoparticle (AgNP stabilizing agent. These nanoparticles were produced by a single step and presented an 11 ± 1 nm diameter. Furthermore, the PS-b-PVP copolymers were also applied as a silica nanoparticle (SiO2NP surface modification agent. The SiO2NP were synthesized by the Stöber method presenting a 72 ± 9 nm diameter. The SiO2NP surface modification by adsorption of PS-b-PVP caused the formation of a 5 ± 1 nm thick polymeric layer, providing the SiO2NP with a hydrophobic surface character. The structural and chemical characteristics shown by PS-b-PVP copolymers highlights their versatility for several applications, such as: water-in-oil emulsifier, stabilizing or coupling agents between inorganic particles and polymeric matrices.

  18. Block copolymer micelle nanolithography on non-conductive substrates

    International Nuclear Information System (INIS)

    A new lithographic technique has been developed and applied to cell adhesion studies and electro-optical material development. Attachment of 6 nm Au particles, in periodic and non-periodic pattern, onto non-conductive substrates has been achieved. This was performed via a combination of diblock copolymer self-assembly and electron beam lithographic techniques. To optimize e-beam resolution on non-conductive materials, an additional carbon layer was thread-coated onto the substrates. This carbon coating and the diblock copolymer used in the self-assembly step were simultaneously removed by a final hydrogen plasma treatment to reveal Au nanodot patterns of unprecedented pattern quality. These optically transparent substrates (glass cover slips) were bio-functionalized via the Au-dot patterns to yield a platform for unique cell adhesion studies. The same Au-dot patterning technique was applied to sapphire substrates, which were subsequently employed to nucleate electro-optically active ZnO nanopost growth

  19. Theory for dynamical self arrest and gelation in microemulsions and the block copolymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sangwook

    2005-05-01

    The main purpose of this work is to investigate the glassy behavior of microemulsions and block copolymers. The origin of glassy behavior in microemulsions and block copolymers is frustration due to a competition between short-range interaction and long range interaction. According to the charge frustrated Ising model, the competition between ferromagnetic interaction and antiferromagnetic interaction is the origin of frustration in microemulsions. The competition between entropic effects and stoichiometric constraints responsible for the formation of micelles in microemulsions can lead to the emergence of a self generated glassy behavior in these systems. In the block copolymer, the competition between the repulsive short range interaction between monomers in polymer chains and the long range interaction by chemical bonds can lead to the emergence of a self generated glassy behavior. The criteria for the fluctuation induced first order transition and our microemulsion and block copolymer glasses are essentially the same. Both are a consequence of the large phase space of low energy excitations (14) (62) (all states with momenta q which fulfill |q| = q{sub m}) and are of at the most a moderate supercooling of the liquid state is required. This is strongly supported by the observation in Ref. (14) that the metastable states which are first to appear at a fluctuation induced first order transition are the ones build by a superposition of large amplitude waves of wavenumber q{sub m}, but with random orientations and phases, i.e. just the ones which form the metastable states of our microemulsion and block copolymer glass. (38)

  20. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    OpenAIRE

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in pH or co-assemble in response to oppositely charged polyelectrolytes (including each other). Such molecules displaying controlled self-assembly may lead to new biocompatible nano-structured material...

  1. SYNTHESIS OF POLY(ETHYLENE TEREPHTHALATE)-POLYCAPROLACTONE BLOCK COPOLYMER BY DIRECT COPOLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Shen-guo Wang; Kai Tang

    1999-01-01

    Poly(ethylene terephthalate)-polycaprolactone block copolymer (PCL-b-PET) is a polyester with improved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)4 was proposed for the synthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and 1H-NMR techniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.

  2. Reversible Micro- and Nano- Phase Programming of Anthraquinone Thermochromism Using Blended Block Copolymers.

    Science.gov (United States)

    Zhang, Yumiao; Lovell, Jonathan F

    2015-12-22

    Here, we present an approach to generate materials with programmable thermochromic transition temperatures (TTTs), based on the reversible microcrystallization of anthraquinone dyes with the assistance of blended Pluronic block copolymers. At temperatures above block copolymer critical micellization temperature (CMT), hydrophobic anthraquinone dyes, including Sudan blue II, were dispersed in copolymer micelles, whereas at lower temperature, the dyes formed microcrystals driven by dye-dye and dye-Pluronic molecular interactions. The crystallization process altered the optical properties of the dye with bathochromatic shifts detectable by eye and the thermochromic process was fully reversible. Not only could Pluronic reversibly incorporate the anthraquinone dyes into micelles at elevated temperatures, but it also modulated the crystallization process and resulting morphology of microcrystals via tuning the molecular interactions when the temperature was lowered. Crystal melting transition points (and TTTs) were in agreement with the CMTs, demonstrating that the thermochromism was dependent on block copolymer micellization. Thermochromism could be readily programmed over a broad range of temperatures by changing the CMT by using different types and concentrations of Pluronics and combinations thereof. PMID:26626998

  3. Synthesis and Characterization of Smart Block Copolymers for Biomineralization and Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kanapathipillai, Mathumai [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in nanotechnology [2], biomineralization [3, 4], drug delivery [5, 6] and gene therapy [7]. In this respect, amphiphilic block copolymers that self-organize in solution have been found to be very versatile [1]. In recent years, polymer-micellar systems have been designed that are adaptable to their environment and able to respond in a controlled manner to external stimuli. In short, synthesis of 'nanoscale objects' that exhibit 'stimulus-responsive' properties is a topic gathering momentum, because their behavior is reminiscent of that exhibited by proteins [8]. By integrating environmentally sensitive homopolymers into amphiphilic block copolymers, smart block copolymers with self assembled supramolecular structures that exhibit stimuli or environmentally responsive properties can be obtained [1]. Several synthetic polymers are known to have environmentally responsive properties. Changes in the physical, chemical or biochemical environment of these polymers results in modulation of the solubility or chain conformation of the polymer [9]. There are many common schemes of engineering stimuli responsive properties into materials [8, 9]. Polymers exhibiting lower critical solution temperature (LCST) are soluble in solvent below a specific temperature and phase separate from solvent above that temperature while polymers exhibiting upper critical solution temperatures (UCST) phase separate below a certain temperature. The solubility of polymers with ionizable

  4. Multiple ordered phases in a block copolymer melt

    DEFF Research Database (Denmark)

    Almdal, K.; Koppi, K.A.; Bates, F.S.;

    1992-01-01

    -order based on discontinuities in the SANS pattern symmetries and intensities and dynamic elastic moduli. At the lowest experimental temperatures the material exhibits a (rippled) lamellar phase. At intermediate temperatures two new ordered phases appear. Above the order-disorder transition temperature a......A poly(ethylenepropylene)-poly(ethylethylene) (PEP-PEE) diblock copolymer containing 65% by volume PEP was investigated using small-angle neutron scattering (SANS) and rheological measurements. Four distinct phases have been identified as a function of temperature: three ordered phases at low...... temperatures and a disordered phase at elevated temperatures. Evaluation of the ordered phases was facilitated by the introduction of long-range order using a shear-orientation technique. SANS data were acquired as a function of temperature for three specimen orientations corresponding to the principle...

  5. Highly ordered palladium nanodots and nanowires from switchable block copolymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bhoje Gowd, E; Nandan, Bhanu; Vyas, Mukesh Kumar; Stamm, Manfred [Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069, Dresden (Germany); Bigall, Nadja C; Eychmueller, Alexander [Physical Chemistry and Electrochemistry, TU Dresden, Bergstrasse 66b, 01062, Dresden (Germany); Schloerb, Heike, E-mail: gowd@ipfdd.d, E-mail: nandan@ipfdd.d [Leibniz Institute for Solid State and Materials Research Dresden, PO Box 27 00 16, D-01171, Dresden (Germany)

    2009-10-14

    We demonstrate a new approach to fabricate highly ordered arrays of nanoscopic palladium dots and wires using switchable block copolymer thin films. The surface-reconstructed block copolymer templates were directly deposited with palladium nanoparticles from a simple aqueous solution. The preferential interaction of the nanoparticles with one of the blocks is mainly responsible for the lateral arrangement of the nanoparticles inside the pores of the templates in addition to the capillary forces. A subsequent stabilization by UV-irradiation followed by pyrolysis in air at 450 {sup 0}C removes the polymer to produce highly ordered metallic nanostructures. We extended this approach to micellar films to obtain metallic nanostructures. This method is highly versatile as the procedure used here is simple, eco-friendly and provides a simple approach to fabricate a broad range of nanoscaled architectures with tunable lateral spacing, and can be extended to systems with even smaller dimensions.

  6. Novel lift-off technique for Transmission Electron Microscopy imaging of block copolymer films

    International Nuclear Information System (INIS)

    We have developed a simple technique to allow for the lift-off and subsequent transfer of poly(styrene-block-ethylene glycol) films to Transmission Electron Microscopy (TEM) grids. The block copolymer is spin coated onto carbon coated mica and annealed. After the thin film is produced it can easily be floated onto water and picked up by a TEM grid. This method offers better control over film processing than dip coating the TEM grid and is also a significant improvement over methods using etchants such as hydrofluoric acid. - Highlights: • We have developed a simple method to lift block copolymer films to TEM grids. • Polymer films prepared on carbon coated mica are easily floated on water. • The new method circumvents the use of harsh chemicals

  7. PVP-b-PEO block copolymers for stable aqueous and ethanolic graphene dispersions.

    Science.gov (United States)

    Perumal, Suguna; Park, Kyung Tae; Lee, Hyang Moo; Cheong, In Woo

    2016-02-15

    The ability to disperse pristine (unfunctionalized) graphene is important for various applications, coating, nanocomposites, and energy related systems. Herein we report that amphiphilic copolymers of poly(4-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) are able to disperse graphene with high concentrations about 2.6mg/mL via sonication and centrifugation. Ethanolic and aqueous highly-ordered pyrolytic graphite (HOPG) dispersions with block copolymers were prepared and they were compared with the dispersions stabilized by P-123 Pluronic® (P123) and poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) synthesized. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman and UV-visible spectroscopic studies confirmed that PVP-b-PEO block copolymers are better stabilizers for HOPG graphene than P123 and PS-b-PEO. X-ray photoelectron spectroscopy and force-distance (F-d) curve analyses revealed that the nitrogen of vinyl pyridine plays a vital role in better attractive interaction with surface of graphene sheet. Thermogravimetric analysis showed that larger amount of PVP-b-PEO was adsorbed onto graphene with longer poly(4-vinyl pyridine) (PVP) block length and in aqueous medium, respectively, and which was consistent with electrical conductivity decreases. This study presents the dispersion efficiency of graphene using PVP-b-PEO varies substantially depending on the lengths of their hydrophobic (PVP) domains. PMID:26606378

  8. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion.

    Science.gov (United States)

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible addition-fragment transfer (RAFT) polymerization, was confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). While the hydrophilic PMOEP block within the amphiphilic block copolymer strongly binds to the enamel surface, the PMMA block forms a hydrophobic shell to prevent acid attack on tooth enamel, thus preventing/reducing acid erosion. The polymer treatment not only effectively decreased the mineral loss of hydroxyapatite (HAP) by 36-46% compared to the untreated control, but also protected the surface morphology of the enamel specimen following exposure to acid. Additionally, experimental results confirmed that low pH values and high polymer concentrations facilitate polymer binding. Thus, the preliminary data suggests that this new amphiphilic diblock copolymer has the potential to be used as a non-fluoride ingredient for mouth-rinse or toothpaste to prevent/reduce tooth erosion. PMID:25419457

  9. Nanostructure of self-assembled rod-coil block copolymer films for photovoltaic applications

    International Nuclear Information System (INIS)

    The nanostructures of a series of rod-coil block copolymers, designed for photovoltaic applications, are studied by atomic force microscopy and transmission electron microscopy. The copolymers are composed of a semiconducting poly-p-phenylenevinylene rod with (2'-ethyl)-hexyloxy side chains and a functionalized coil block of various length and flexibility. Both, as deposited and annealed block copolymer films were investigated. The results show that highly ordered structures are only obtained if the coil block is characterized by a glass transition temperature which is significantly lower than the melting temperature of the alkyl side chains. For this material a high molecular mobility and strong driving force for crystallization of the rigid block can be achieved simultaneously. For the smallest coil to rod length ratio, we found a lamellar morphology with perpendicularly oriented lamellae with respect to the substrate. Electron diffraction data show the presence of a periodical molecular arrangement with a characteristic distance of 0.94 nm that is attributed to the distance between conjugated chains separated by the layers of alkyl sidechains

  10. Environment-induced self-assembly in phase separated block copolymer systems: A SANS investigation

    International Nuclear Information System (INIS)

    In this research, we examine the effect of non-selective solvent on the large-scale mesoscopic ordering in asymmetric block copolymers, poly(styrene-block-ethylene/butylene-block-styrene) (SEBS) using small angle neutron scattering technique (SANS). SANS measurements were carried out over a wide range of concentrations and temperatures. Evolution of the self-assembled phase morphology in such polymer with the thermodynamic selectivity of solvent, temperature and concentration has been discussed. Correlation between morphology and thermorheological behavior of the gels has also been established

  11. Self-assembling Behavior of Amphiphilic Copolymer Containing Cross-linked Hydrophilic Block in Ethanol

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-assembly behavior of the amphiphilic block copolymer poly( methyl methacrylate)-block-poly( lead dimethacrylate) (PMMA-b-PLDMA) with cross-linked hydrophilic block (PLDMA) in ethanol was investigated. The results show that the size and morphology of the resulting micelle or micellar aggregates are ascribed to the content of ethanol and the nature of the solvent mixture. PbS nanoparticles were formed in the micelle by in situ reaction with H2S gas. The morphology and size of the self-assembly objects were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  12. Hydrogen-bonded multilayers of micelles of a dually responsive dicationic block copolymer

    OpenAIRE

    Erel, İrem; Karahan, H. Enis; Demirel, A. Levent; Tuncer, Cansel; Bütün, Vural

    2012-01-01

    We report the fabrication of hydrogen-bonded multilayers of micelles of a dually responsive, dicationic block copolymer, poly[2-(N-morpholino)ethyl methacrylate-block-2-(diisopropylamino)ethyl methacrylate] (PMEMA-b-PDPA). By taking advantage of the difference in the hydrophilicity of PMEMA and PDPA blocks, micelles with a PMEMA-corona and a PDPA-core were obtained above pH 6.5 and were assembled layer-by-layer at the surface with tannic acid (TA) at pH 7.4 through hydrogen bonding interactio...

  13. Application of Block Copolymer in Three-Liquid-Phase Extraction System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel three-liquid-phase extraction system (TES) composed of butyl acetate, block copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide and ammonium sulphate aqueous solution [(NH4)2SO4] as top, middle, and bottom phase, respectively, has been developed. The copolymer recycling and partitioning behavior of penicillin V has been studied in this system. Results show that the copolymer could be purified and recycled and penicillin V of the filtrated ferment broth could be partitioned unevenly among the phases and purified in the top phase of this TES. About 90 wt.% of penicillin V could be distributed into the top phase around pH 2.5 and only less than 0.1 wt.% left in the bottom phase.

  14. Modular synthesis of a block copolymer with a cleavable linkage via “click” chemistry

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A diblock copolymer poly(ethylene glycol)-block-polystyrene or PEG-b-PS with an olefinic double bond at the PEG and PS junction has been prepared by modular synthesis via"click"chemistry.This involved the synthesis of PS by atom transfer radical polymerization and the nucleophilic substitution of the terminal bromide group with azide to yield azide-terminated PS. PEG with an alkynyl terminal group was prepared from reacting carboxyl-end-functionalized PEG with 4-hydroxybut-2-enyl prop-2-ynyl succinate,which contained an alkynyl group as well as an olefin group.The PS and PEG polymers were linked via the 1,3-dipolar cycloaddition of the end azide and alkyne groups.The obtained copolymer was characterized by 1H NMR spectroscopy and size exclusion chromatography(SEC).SEC analysis indicated that the diblock copolymer produced could be readily cleaved by ozonolysis to regenerate the constituent homopolymers.

  15. Morphological Studies on Sn-O Coordination Driving Self-assembly of Well-defined Organotin-containing Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    Jian Jiang; Wei Yan; Ling-yan Liu; Wei-xing Chang; Jing Li

    2014-01-01

    A tin-oxygen coordination driving self-assembly was developed in the block copolymers containing organotin,which were prepared by the radical addition-fraction transfer (RAFT) method and characterized by the gel-permeation chromatography (GPC) and 1H-NMR.And the self-assemblies of these block copolymers with various chain length ratios in the different concenaations in CHCl3 were stable according to the results of DLS and TEM.Additionally,it was also given an insight investigation on the regulation of self-assembly of the block copolymers by adding dibutyltin dichloride and a possible mechanism was proposed.

  16. Electrospinning of a functional perfluorinated block copolymer as a powerful route for imparting superhydrophobicity and corrosion resistance to aluminum substrates.

    Science.gov (United States)

    Grignard, Bruno; Vaillant, Alexandre; de Coninck, Joel; Piens, Marcel; Jonas, Alain M; Detrembleur, Christophe; Jerome, Christine

    2011-01-01

    Superhydrophobic aluminum surfaces with excellent corrosion resistance were successfully prepared by electrospinning of a novel fluorinated diblock copolymer solution. Micro- and nanostructuration of the diblock copolymer coating was obtained by electrospinning which proved to be an easy and cheap electrospinning technology to fabricate superhydrophobic coating. The diblock copolymer is made of poly(heptadecafluorodecylacrylate-co-acrylic acid) (PFDA-co-AA) random copolymer as the first block and polyacrylonitrile (PAN) as the second one. The fluorinated block promotes hydrophobicity to the surface by reducing the surface tension, while its carboxylic acid functions anchor the polymer film onto the aluminum surface after annealing at 130 °C. The PAN block of this copolymer insures the stability of the structuration of the surface during annealing, thanks to the infusible character of PAN. It is also demonstrated that the so-formed superhydrophobic coating shows good adhesion to aluminum surfaces, resulting in excellent corrosion resistance. PMID:21141949

  17. Preparation, Stability, and Bio-Compatability of Block Copolymer Vesicles

    Science.gov (United States)

    Discher, Dennis; Lee, James C.-M.; Bermudez, Harry; Bates, Frank; Discher, Bohdana

    2001-03-01

    Vesicles made completely from diblock copolymers polymersomes can be stably prepared by a wide range of techniques common to liposomes. Processes such as film rehydration, sonication, and extrusion can generate many micron giants as well as monodisperse, 100 nm vesicles of PEO-PEE (polyethyleneoxide polyethylethylene) or PEO PBD (polyethyleneoxide polybutadiene). These thick-walled vesicles of polymer can encapsulate macromolecules just as liposomes can, but, unlike many pure liposome systems, these polymersomes exhibit no in-surface thermal transitions and a sub-population even survive autoclaving. Suspension in blood plasma has no immediate ill-effect on vesicle stability, and neither adhesion nor stimulation of phagocytes are apparent when giant polymersomes are held in direct, protracted contact. Proliferating cells, in addition, are unaffected when cultured for an extended time with an excess of polymersomes, and several injections of 10 mg doses into rats show no ill-effect. The results are consistent with the steric stabilization that PEG-lipid can impart to liposomes, but the present single-component polymersomes are far more stable mechanically and are not limited by PEG driven micellization.

  18. Thin Isoporous Block Copolymer Membranes: It Is All about the Process.

    Science.gov (United States)

    Hahn, Janina; Clodt, Juliana I; Abetz, Clarissa; Filiz, Volkan; Abetz, Volker

    2015-09-30

    The combination of the self-assembly of amphiphilic block copolymers and the nonsolvent induced phase inversion process offers an efficient way to isoporous integral-asymmetric membranes. In this context we report fast, easily upscalable and material reducing ways to thin self-assembled membranes. Therefore, we succeeded to implement a spray or dip coating step into the membrane formation process of different diblock copolymers like polystyrene-block-poly(4-vinylpyridine), poly(α-methylstyrene)-bock-poly(4-vinylpyridine), and polystyrene-block-poly(iso-propylglycidyl methacrylate). The formation of hexagonal pore structures was possible using a highly diluted one solvent system allowing the reduction of diblock copolymer consumption and therefore the production costs are minimized compared to conventional blade casting approaches. The broad applicability of the process was proven by using different flat and hollow fiber support materials. Furthermore, the membranes made by this new method showed a more than 6-fold increase in water flux compared to conventional polystyrene-block-poly(4-vinylpyridine) membranes with similar pore sizes prepared by blade casting. The membranes could be proven to be stable at transmembrane pressures of 2 bar and showed a pH responsive flux behavior over several cycles. PMID:26349610

  19. Block Copolymer Modified Epoxy Amine System for Reactive Rotational Molding: Structures, Properties and Processability

    Science.gov (United States)

    Lecocq, Eva; Nony, Fabien; Tcharkhtchi, Abbas; Gérard, Jean-François

    2011-05-01

    Poly(styrene-butadiene-methylmethacrylate) (SBM) and poly(methylmethacrylate-butyle-acrylate-methylmethacrylate) (MAM) triblock copolymers have been dissolved in liquid DGEBA epoxy resin which is subsequently polymerized by meta-xylene diamine (MXDA) or Jeffamine EDR-148. A chemorheology study of these formulations by plate-plate rheology and by thermal analysis has allowed to conclude that the addition of these copolymer blocks improve the reactive rotational moulding processability without affecting the processing time. Indeed, it prevents the pooling of the formulation at the bottom of the mould and a too rapid build up of resin viscosity of these thermosetting systems. The morphology of the cured blends examined by scanning electron microscopy (SEM) shows an increase of fracture surface area and thereby a potential increase of the toughness with the modification of epoxy system. Dynamic mechanical spectroscopy (DMA) and opalescence of final material show that the block PMMA, initially miscible, is likely to induce phase separation from the epoxy-amine matrix. Thereby, the poor compatibilisation between the toughener and the matrix has a detrimental effect on the tensile mechanical properties. The compatibilisation has to be increased to improve in synergy the processability and the final properties of these block copolymer modified formulations. First attempts could be by adapting the length and ratio of each block.

  20. Micellar cathodes from self-assembled nitroxide-containing block copolymers in battery electrolytes.

    Science.gov (United States)

    Hauffman, Guillaume; Maguin, Quentin; Bourgeois, Jean-Pierre; Vlad, Alexandru; Gohy, Jean-François

    2014-01-01

    This contribution describes the synthesis of block copolymers containing electrochemically active blocks, their micellization, and finally their use as micellar cathodes in a lithium battery. The self-assembly of the synthesized poly(styrene)-block-poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PS-b-PTMA) diblock copolymers is realized in a typical battery electrolyte made of 1 m lithium trifluoromethanesulfonate dissolved in a mixture of ethylene carbonate/diethyl carbonate/dimethyl carbonate(1:1:1, in volume). Dynamic light scattering and atomic force micro-scopy indicate the formation of well-defined spherical micelles with a PS core and a PTMA corona. The electrochemical properties of those micelles are further investigated. Cyclic voltammograms show a reversible redox reaction at 3.6 V (vs Li(+) /Li). The charge/discharge profiles indicate a flat and reversible plateau around 3.6 V (vs Li(+) /Li). Finally, the cycling performances of the micellar cathodes are demonstrated. Such self-assembled block copolymers open new opportunities for nanostructured organic radical batteries. PMID:24127365

  1. Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

    Science.gov (United States)

    Li, Junbo; Zhao, Jianlong; Wu, Wenlan; Liang, Ju; Guo, Jinwu; Zhou, Huiyun; Liang, Lijuan

    2016-06-01

    In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]- block-(N-isopropylacrylamide) (PMMPImB- b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB- b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N-. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N-, the micellization of self-assembling PMMPImB- b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB-(CF3SO2)2N- surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

  2. Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites.

    Science.gov (United States)

    Wang, Miao; Olszewska, Anna; Walther, Andreas; Malho, Jani-Markus; Schacher, Felix H; Ruokolainen, Janne; Ankerfors, Mikael; Laine, Janne; Berglund, Lars A; Osterberg, Monika; Ikkala, Olli

    2011-06-13

    We present a facile ionic assembly between fibrillar and spherical colloidal objects toward biomimetic nanocomposites with majority hard and minority soft domains based on anionic reinforcing native cellulose nanofibrils and cationic amphiphilic block copolymer micelles with rubbery core. The concept is based on ionic complexation of carboxymethylated nanofibrillated cellulose (NFC, or also denoted as microfibrillated cellulose, MFC) and micelles formed by aqueous self-assembly of quaternized poly(1,2-butadiene)-block-poly(dimethylaminoethyl methacrylate) with high fraction of the NFC reinforcement. The adsorption of block copolymer micelles onto nanocellulose is shown by quartz crystal microbalance measurements, atomic force microscopy imaging, and fluorescent optical microscopy. The physical properties are elucidated using electron microscopy, thermal analysis, and mechanical testing. The cationic part of the block copolymer serves as a binder to NFC, whereas the hydrophobic rubbery micellar cores are designed to facilitate energy dissipation and nanoscale lubrication between the NFC domains under deformation. We show that the mechanical properties do not follow the rule of mixtures, and synergistic effects are observed with promoted work of fracture in one composition. As the concept allows wide possibilities for tuning, the work suggests pathways for nanocellulose-based biomimetic nanocomposites combining high toughness with stiffness and strength. PMID:21517114

  3. Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

    Science.gov (United States)

    Li, Junbo; Zhao, Jianlong; Wu, Wenlan; Liang, Ju; Guo, Jinwu; Zhou, Huiyun; Liang, Lijuan

    2016-04-01

    In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]-block-(N-isopropylacrylamide) (PMMPImB-b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB-b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N-. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N-, the micellization of self-assembling PMMPImB-b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB- (CF3SO2)2N- surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

  4. Ionic Conductivity and Gas Permeability of Polymerized Ionic Liquid Block Copolymer Membranes

    Science.gov (United States)

    Evans, Christopher; Sanoja, Gabriel; Schneider, Yanika; Modestino, Miguel; Segalman, Rachel; Joint CenterArtificial Photosynthesis Team

    2014-03-01

    Polymer membranes for many energy applications, such as solar-to-hydrogen fuel production, require ionic conductivity while acting as gas diffusion barriers. We have synthesized a diblock copolymer consisting of poly(styrene-block-(4-(2-methacrylamidoethyl)-imidazolium trifluoroacetate) by treating poly(styrene-block-histamine methacrylamide) (PS- b-PHMA) with trifluoroacetic acid. The PS block serves as the structural support while the imidazolium derivative is an ion conducting polymerized ionic liquid (PIL). Small angle X-ray scattering and transmission electron microscopy demonstrate that the block copolymer self-assembles into well-ordered nanostructures, with lamellae and hexagonally packed cylindrical morphologies. The ionic conductivities of the PS-b-PHMA materials were as high as 2 x 10-4 S/cm while an order of magnitude increase in conductivity was observed upon conversion to PS-b-PIL. The ionic conductivity of the PS-b-PIL increased by a factor of ~ 4 up to 1.2 x 10-3 S/cm as the PIL domain size increased from 20 to 40 nm. These insights allow for the rational design of high performance ion conducting membranes with even greater conductivities via precise morphological control. Additionally, the role of thermal annealing on the ionic conductivity and gas permeability of copolymer membranes was investigated.

  5. Fluctuations, conformational asymmetry and block copolymer phase behaviour

    DEFF Research Database (Denmark)

    Bates, F.S.; Schulz, M.F.; Khandpur, A.K.;

    1994-01-01

    parameter and degree of polymerization, respectively. epsilon accounts for differences in the conformational and volume-filling characteristics of each block. Conformational asymmetry, epsilon not equal 1, produces an asymmetric phase diagram around f = 1/2. The importance of fluctuation effects are...

  6. Effect of annealing and UV-radiation time over micropore architecture of self-assembled block copolymer thin film

    Directory of Open Access Journals (Sweden)

    G. del C. Pizarro

    2015-06-01

    Full Text Available Block copolymers have been recognized as versatile materials to prepare nanoporous polymer films or membranes, but their potential has not been completely explored. This study focuses on the formation and characterization of nanoporous polymer films based on poly(styrene-block-(methylmethacrylate/methacrylic acid; (PS-b-MMA/MAA were obtained through atom transfer radical polymerization (ATRP, by using two different protocols: annealing and annealingirradiation; for improving the formation of microporous surface. The composition, crystallinity and structural order of the films were studied by Raman spectroscopy. The film polymer thickness was obtained through very high resolution ellipsometry (VHRE. Finally, atomic force microcopy (AFM and scanning electron microscopy (SEM techniques were used to detect changes in the porous-structure. These results show that the morphological properties of the block copolymer were affected via the modification of two variables, UV-radiation time and annealing. SEM and AFM micrographs showed that the morphology exhibit a porous ordered structure. Contact angle measurement suggests additional interactions between hydrophilic functional groups that influence the film wettability.

  7. Diblock copolymers comprising poly(2-vinylpyridine-co-acrylonitrile) and polystyrene blocks by nitroxide-mediated radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Lokaj, Jan; Poláková, Lenka; Holler, Petr; Starovoytova, Larisa; Štěpánek, Petr; Diat, O.

    Prague : Institute of Macromolecular Chemistry AS CR, 2006. s. 41. [SONS Networking Activity Workshop: Structure and properties of self-organized amphiphilic copolymers. 04.10.2006-07.10.2006, Prague] R&D Projects: GA ČR GESON/03/E001 Keywords : block copolymers * nitroxide-mediated radical polymerization * 2-vinylpyridine Subject RIV: CD - Macromolecular Chemistry

  8. Block Copolymers of Ethylene Oxide and Styrene Oxide:New Copolymer Surfactants(Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    Zhuo Yang; David Attwood; Colin Booth

    2003-01-01

    @@ 1 Introduction The range and application, actual and potential, of water-soluble block-copoly (oxyalkylene)s have beenextensively reviewed in recent compilations by edited by Nace[1] and by Alexandridis and Lindman[2].

  9. Thin polymer films of block copolymers and blend/nanoparticle composites

    Science.gov (United States)

    Kalloudis, Michail

    In this thesis, atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical microscopy techniques were used to investigate systematically the self-assembled nanostructure behaviour of two different types of spin-cast polymer thin films: poly(isoprene-b-ethylene oxide), PI-b-PEO diblock copolymers and [poly(9,9-dioctylfluorene-co-benzothiadiazole)]:poly[9,9- dioctyfluorene-co-N-(4-butylphenyl)-diphenylamine], F8BT:TFB conjugated polymer blends. In the particular case of the polymer blend thin films, the morphology of their composites with cadmium selenide (CdSe) quantum dot (QD) nanoparticles was also investigated. For the diblock copolymer thin films, the behaviour of the nanostructures formed and the wetting behaviour on mica, varying the volume fraction of the PEO block (fPEO) and the average film thickness was explored. For the polymer blend films, the effect of the F8BT/TFB blend ratio (per weight), spin-coating parameters and solution concentration on the phase-separated nanodomains was investigated. The influence of the quantum dots on the phase separation when these were embedded in the F8BT:TFB thin films was also examined. It was found that in the case of PI-b-PEO copolymer thin films, robust nanostructures, which remained unchanged after heating/annealing and/or ageing, were obtained immediately after spin coating on hydrophilic mica substrates from aqueous solutions. The competition and coupling of the PEO crystallisation and the phase separation between the PEO and PI blocks determined the ultimate morphology of the thin films. Due to the great biocompatible properties of the PEO block (protein resistance), robust PEO-based nanostructures find important applications in the development of micro/nano patterns for biological and biomedical applications. It was also found that sub-micrometre length-scale phase-separated domains were formed in F8BT:TFB spin cast thin films. The nanophase-separated domains of F8BT-rich and TFB-rich areas

  10. Ethylene oxide-block-butylene oxide copolymer uptake by silicone hydrogel contact lens materials

    International Nuclear Information System (INIS)

    Four major types of silicone hydrogel contact lens material have been investigated following treatments in aqueous solutions containing poly(ethylene oxide) and poly(butylenes oxide) block copolymer (EO–BO). The extent of lens surface modification by EO–BO and the degree of bulk uptake were studied using X-ray photoelectron spectroscopy (XPS) and ultra-performance liquid chromatography (UPLC), respectively. The experimental results suggest that different interaction models exist for the lenses, highlighting the influence of both surface and bulk composition, which greatly differs between the lenses examined. Specifically, lenses with hydrophilic surface treatments, i.e., PureVision® (balafilcon A) and O2OPTIX (lotrafilcon B), demonstrated strong evidence of preferential surface adsorption within the near-surface region. In comparison, surface adsorption on ACUVUE® Oasys® (senofilcon A) and Biofinity® (comfilcon A) was limited. As for bulk absorption, the amount of EO–BO uptake was the greatest for balafilcon A and comfilcon A, and least for lotrafilcon B. These findings confirm the presence of molecular concentration gradients within the silicone hydrogel lenses following exposure to EO–BO solutions, with the nature of such concentration gradients found to be lens-specific. Together, the results suggest opportunities for compositional modifications of lenses for improved performance via solution treatments containing surface-active agents.

  11. Ethylene oxide-block-butylene oxide copolymer uptake by silicone hydrogel contact lens materials

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Yuchen [Department of Materials Science and Engineering, University of Florida, Rhines Hall 100, Gainesville, FL 32611 (United States); Ketelson, Howard [Alcon Inc., Research and Development, Vision Care, 6201 South Freeway, Fort Worth, TX 76134 (United States); Perry, Scott S., E-mail: ssp@mse.ufl.edu [Department of Materials Science and Engineering, University of Florida, Rhines Hall 100, Gainesville, FL 32611 (United States)

    2013-05-15

    Four major types of silicone hydrogel contact lens material have been investigated following treatments in aqueous solutions containing poly(ethylene oxide) and poly(butylenes oxide) block copolymer (EO–BO). The extent of lens surface modification by EO–BO and the degree of bulk uptake were studied using X-ray photoelectron spectroscopy (XPS) and ultra-performance liquid chromatography (UPLC), respectively. The experimental results suggest that different interaction models exist for the lenses, highlighting the influence of both surface and bulk composition, which greatly differs between the lenses examined. Specifically, lenses with hydrophilic surface treatments, i.e., PureVision{sup ®} (balafilcon A) and O{sub 2}OPTIX (lotrafilcon B), demonstrated strong evidence of preferential surface adsorption within the near-surface region. In comparison, surface adsorption on ACUVUE{sup ®} Oasys{sup ®} (senofilcon A) and Biofinity{sup ®} (comfilcon A) was limited. As for bulk absorption, the amount of EO–BO uptake was the greatest for balafilcon A and comfilcon A, and least for lotrafilcon B. These findings confirm the presence of molecular concentration gradients within the silicone hydrogel lenses following exposure to EO–BO solutions, with the nature of such concentration gradients found to be lens-specific. Together, the results suggest opportunities for compositional modifications of lenses for improved performance via solution treatments containing surface-active agents.

  12. Fast & scalable pattern transfer via block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars;

    2015-01-01

    solutions with selective solvents relative to the majority block. The pattern is directly formed during spin-casting at room temperature, which takes less than 20 seconds, without any preliminary surface treatment of the substrate and without any subsequent annealing. The self-assembled BCPs are transformed...... relying on long range lateral order, including fabrication of substrates for catalysis, solar cells, sensors, ultrafiltration membranes and templating of semiconductors or metals....

  13. Pattern formation and phase behavior in PS-B-Si containing block copolymer thin film

    Science.gov (United States)

    Hsieh, I.-Fan

    Since the top-down approaches, such as the extremely ultraviolet (EUV) technique and the high-index fluid-based immersion ArF lithography, may be cover one or two generations, these lithography technologies are getting more severe for the feature size scaling down to sub 10 nm. The directed self-assembly technology of block copolymers is one of the candidates for next generation lithography which can afford feature sizes that are dictated by the molecular weight of the block copolymer and are typically 15 to 30 nm. Directed self-assembly of block copolymers has attracted attention as a technology to extend photoresist-based lithography to smaller dimensions. It has been demonstrated that the directed self assembly of block copolymer offers a new route to perfect nanolithographic pattering at sub-50 nm length scale with molecular scale precision. For application in electronic media, it requires large-area, long-range ordered structures, which is both a kinetic and thermodynamic problem and requires subtle balance of various parameters and processing conditions. So far, block copolymer thin films have already achieved certain success, mainly with higher molecular weights and a feature size of ˜30 nm. Several challenges still remain, such as (a) the generation of long-range ordered structure with smaller feature sizes (domain size block copolymers have emerged as next generation block copolymers for nanolithography. Their films can be processed under dry conditions using oxygen plasma to produce inorganic, silica patterns which enables their integration into existing device fabrication. Also, the large thermodynamic incompatibility of silicon-containing polymers with other organic polymers is favorable for patterns with small domains sizes, large correlation lengths, and low interfacial roughness. In PS-b-PDMS system, a solvent-induced spherical structure was obtained and stabilized by preparing both the bulk and thin film from propylene glycol methyl ether acetate

  14. Thermal Analysis, Structural Studies and Morphology of Spider Silk-like Block Copolymers

    Science.gov (United States)

    Huang, Wenwen

    Spider silk is a remarkable natural block copolymer, which offers a unique combination of low density, excellent mechanical properties, and thermal stability over a wide range of temperature, along with biocompatibility and biodegrability. The dragline silk of Nephila clavipes, is one of the most well understood and the best characterized spider silk, in which alanine-rich hydrophobic blocks and glycine-rich hydrophilic blocks are linked together generating a functional block copolymer with potential uses in biomedical applications such as guided tissue repair and drug delivery. To provide further insight into the relationships among peptide amino acid sequence, block length, and physical properties, in this thesis, we studied synthetic proteins inspired by the genetic sequences found in spider dragline silks, and used these bioengineered spider silk block copolymers to study thermal, structural and morphological features. To obtain a fuller understanding of the thermal dynamic properties of these novel materials, we use a model to calculate the heat capacity of spider silk block copolymer in the solid or liquid state, below or above the glass transition temperature, respectively. We characterize the thermal phase transitions by temperature modulated differential scanning calorimetry (TMDSC) and thermogravimetric analysis (TGA). We also determined the crystallinity by TMDSC and compared the result with Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). To understand the protein-water interactions with respect to the protein amino acid sequence, we also modeled the specific reversing heat capacity of the protein-water system, Cp(T), based on the vibrational, rotational and translational motions of protein amino acid residues and water molecules. Advanced thermal analysis methods using TMDSC and TGA show two glass transitions were observed in all samples during heating. The low temperature glass transition, Tg(1), is related to

  15. Computational Investigation of Block Copolymer Surfactants for Stabilizing Fluctuation-Induced Polymeric Microemulsions

    Science.gov (United States)

    Delaney, Kris; Fredrickson, Glenn

    2013-03-01

    High molecular weight diblock copolymers introduced into a blend of immiscible homopolymers can act as a surfactant to suppress macroscopic two-fluid phase separation. With variation of block copolymer composition, the crossover between low-temperature ordering into microphase or macrophase separated states is marked by a mean-field isotropic Lifshitz multi-critical point. Strong fluctuations close to the Lifshitz point are observed to suppress the low-temperature ordering; a microemulsion state emerges, with large, co-continuous domains of segregated fluid lacking any long-range order. We study this phenomenon with fully fluctuating field-theoretic simulations based on complex Langevin sampling, and we attempt to design new block polymer surfactants that can produce the microemulsion state with a wider composition tolerance.

  16. Preparation and properties of proton conducting blending polymers with fluorous block copolymers as compatibilizers

    Energy Technology Data Exchange (ETDEWEB)

    Shi, K. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation; Murphy, J.; Sieb, N.; Holdcroft, S. [Simon Fraser Univ., Burnaby, BC (Canada). Dept. of Chemistry]|[National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2005-07-01

    This paper presented the results of an experiment in which 3 series of membranes were prepared by blending polyvinylidene difluoride (PVDF) or poly(vinylidene difluoride-co-hexafluoropropylene) (P(VDF/HFP)) with sulfonated poly(ether ether ketone) (S-PEEK), sulfonated polysulfone (SPU), or sulfonated polystyrene in order to develop novel Proton Exchange Membranes (PEMs) suitable for melt processing. The incorporation of fluorine-containing block copolymer into the blended system resulted in the preparation of acceptable proton conductivity and low water containing PEM materials. The effect of sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene block copolymers as compatibilizers was also investigated. It was observed that conductivity was enhanced for S-PEEK/fluoropolymer blends. Microstructures for the blends were examined by transmission electron microscope and scanning electron microscope.

  17. Functionalization of carbon nanofibers with elastomeric block copolymer using carbodiimide chemistry

    International Nuclear Information System (INIS)

    Surface functionalization of carbon nanofibers (CNFs) with aminopropyl terminated polydimethylsiloxane [(PDMS-NH2)] and other organic diamines was achieved using carbodiimide chemistry. The carbodiimide chemistry provides faster reaction rate so that the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. CNF functionalized with PDMS-NH2 fibers were further functionalized with oligomer of polyimide (6FDA-BisP) using imidization reaction. The formation of block copolymer on the surface of CNF is proposed as an effective method to engineer the interphase between the fiber and the polymer, which is essential to modulate and enhance the properties of the nanocomposite. The efficiency of the carbodiimide chemistry to functionalize amine terminated groups on CNF and the functionalization of block copolymer was characterized using thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy.

  18. Thermally induced structural evolution and performance of mesoporous block copolymer-directed alumina perovskite solar cells.

    KAUST Repository

    Tan, Kwan Wee

    2014-04-11

    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI(3-x)Cl(x)) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI(3-x)Cl(x) material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance.

  19. Structural and Mechanical Hysteresis at the Order-Order Transition of Block Copolymer Micellar Crystals

    Directory of Open Access Journals (Sweden)

    Theresa A. LaFollette

    2011-01-01

    Full Text Available Concentrated solutions of a water-soluble block copolymer (PEO20-(PPO70-(PEO20 show a thermoreversible transition from a liquid to a gel. Over a range of concentration there also exists an order-order transition (OOT between cubically-packed spherical micelles and hexagonally-packed cylindrical micelles. This OOT displays a hysteresis between the heating and cooling transitions that is observed at both the macroscale through rheology and nanoscale through small angle neutron scattering (SANS. The hysteresis is caused by the persistence of the cubically-packed spherical micelle phase into the hexagonally-packed cylindrical micelle phase likely due to the hindered realignment of the spherical micelles into cylindrical micelles and then packing of the cylindrical micelles into a hexagonally-packed cylindrical micelle phase. This type of hysteresis must be fully characterized, and possibly avoided, for these block copolymer systems to be used as templates in nanocomposites.

  20. Filtration on block copolymer solution used in directed self assembly lithography

    Science.gov (United States)

    Umeda, Toru; Takakura, Tomoyuki; Tsuzuki, Shuichi

    2016-03-01

    In this paper, we presented the filtration effects on block copolymers (BCP) that are commonly used in directed self-assembly lithographic (DSAL) imaging schemes. Specifically we focused on filtration effects on micro-contaminants such as metal ions and metal induced gels. Gel removal efficiency studies carried out with HDPE, Nylon and PTFE filters pointed out that Nylon 6,6 membrane is the most effective in removing gels in block copolymer (BCP) solutions. Metal removal efficiency studies were conducted using multistep filtrations such as repetitive filtration of single membrane material and combination of different type of membranes. Results showed that a combination of Nylon-6,6 and ion-exchange filters is highly effective in reducing metals such as Li, Mg and Al to > 99.99% efficiency. The mechanism of metal removal efficiency is discussed in detail.

  1. Directed self-assembly of block copolymers for next generation nanolithography

    Directory of Open Access Journals (Sweden)

    Seong-Jun Jeong

    2013-12-01

    Full Text Available Directed self-assembly of block copolymers has received a great deal of research attention as a promising nanolithography to complement the intrinsic limitations of conventional photolithography. In this review, we highlight the recent progress in the development of the directed self-assembly process for practical utilization in semiconductor applications. Various advanced directed self-assembly approaches are examined, in which block copolymer self-assembly is synergistically integrated with conventional photolithography, such as ArF lithography or I-line lithography, via either epitaxial self-assembly or the graphoepitaxy principle. We focus on the practical advantages anticipated from directed self-assembly integration, such as pattern density multiplication, feature size uniformity improvement, line edge roughness reduction, as well as cost reduction. Additionally, a direction for future research on directed self-assembly is suggested with diverse potential applications.

  2. Micellar Self-Assembly of Block Copolymers for Fabrication of Nanostructured Membranes

    KAUST Repository

    Marques, Debora S.

    2013-11-01

    This research work examines the process of block copolymer membrane fabrication by self-assembly combined by non-solvent induced phase separation. Self-assembly takes place from the preparation of the primordial solution until the moment of immersion in a non-solvent bath. These mechanisms are driven thermodynamically but are limited by kinetic factors. It is shown in this work how the ordering of the assembly of micelles is improved by the solution parameters such as solvent quality and concentration of block copolymer. Order transitions are detected, yielding changes in the morphology. The evaporation of the solvents after casting is demonstrated to be essential to reach optimum membrane structure. The non-solvent bath stops the phase separation at an optimum evaporation time.

  3. Self-assemblies of magnetic nanoparticles and di-block copolymers: Magnetic micelles and vesicles

    International Nuclear Information System (INIS)

    Magnetic nanocomposites are obtained by the self-assembly in water of polypeptide-based di-block copolymers polybutadiene-b-poly(glutamic acid) combined with hydrophobic γ-Fe2O3 nanoparticles. These hybrid supramolecular objects are either-(3D) spherical micelles filled with a hydrophobic ferrofluid at a concentration as high as 45 vol% or-hollow vesicles with a (2D) magnetic membrane. In this last case, the organic amphiphile copolymers are able to confine the hydrophobic nanoparticles within the thin layer of polybutadiene blocks. We probe these objects by atomic force microscopy, by small-angle neutron scattering (SANS) and by light scattering. Furthermore, anisotropic SANS data bring the experimental evidence of the capability to modify the shape of the mineralized membranes in response to a magnetic field intensity as low as 290 G

  4. Block copolymer with simultaneous electric and ionic conduction for use in lithium ion batteries

    Science.gov (United States)

    Javier, Anna Esmeralda K; Balsara, Nitash Pervez; Patel, Shrayesh Naran; Hallinan, Jr., Daniel T

    2013-10-08

    Redox reactions that occur at the electrodes of batteries require transport of both ions and electrons to the active centers. Reported is the synthesis of a block copolymer that exhibits simultaneous electronic and ionic conduction. A combination of Grignard metathesis polymerization and click reaction was used successively to synthesize the block copolymer containing regioregular poly(3-hexylthiophene) (P3HT) and poly(ethylene oxide) (PEO) segments. The P3HT-PEO/LiTFSI mixture was then used to make a lithium battery cathode with LiFePO.sub.4 as the only other component. All-solid lithium batteries of the cathode described above, a solid electrolyte and a lithium foil as the anode showed capacities within experimental error of the theoretical capacity of the battery. The ability of P3HT-PEO to serve all of the transport and binding functions required in a lithium battery electrode is thus demonstrated.

  5. Laser Writing Block Copolymer Self-Assembly on Graphene Light-Absorbing Layer.

    Science.gov (United States)

    Jin, Hyeong Min; Lee, Seung Hyun; Kim, Ju Young; Son, Seung-Woo; Kim, Bong Hoon; Lee, Hwan Keon; Mun, Jeong Ho; Cha, Seung Keun; Kim, Jun Soo; Nealey, Paul F; Lee, Keon Jae; Kim, Sang Ouk

    2016-03-22

    Recent advance of high-power laser processing allows for rapid, continuous, area-selective material fabrication, typically represented by laser crystallization of silicon or oxides for display applications. Two-dimensional materials such as graphene exhibit remarkable physical properties and are under intensive development for the manufacture of flexible devices. Here we demonstrate an area-selective ultrafast nanofabrication method using low intensity infrared or visible laser irradiation to direct the self-assembly of block copolymer films into highly ordered manufacturing-relevant architectures at the scale below 12 nm. The fundamental principles underlying this light-induced nanofabrication mechanism include the self-assembly of block copolymers to proceed across the disorder-order transition under large thermal gradients, and the use of chemically modified graphene films as a flexible and conformal light-absorbing layers for transparent, nonplanar, and mechanically flexible surfaces. PMID:26871736

  6. Advantages and limitations of density functional theory in block copolymer directed self-assembly

    Science.gov (United States)

    Liu, Jimmy; Laachi, Nabil; Delaney, Kris T.; Fredrickson, Glenn H.

    2015-03-01

    A major challenge in the application of block copolymer directed self-assembly (DSA) to advanced lithography is the exploration of large design spaces, including the selection of confinement shape and size, surface chemistry to affect wetting conditions, copolymer chain length and block fraction. To sweep such large spaces, a computational model is ideally both fast and accurate. In this study, we investigate various incarnations of the density functional theory (DFT) approach and evaluate their suitability to DSA applications. We introduce a new optimization scheme to capitalize on the speed advantages of DFT, while minimizing loss of accuracy relative to the benchmark of self-consistent field theory (SCFT). Although current DFT models afford a 100-fold reduction in computational complexity over SCFT, even the best optimized models fail to match SCFT density profiles and make extremely poor predictions of commensurability windows and defect energetics. These limitations suggest that SCFT will remain the gold standard for DSA simulations in the near future.

  7. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  8. Association and Structure of Thermo Sensitive Comblike Block Copolymers in Aqueous Solutions

    International Nuclear Information System (INIS)

    The structures and association properties of thermo sensitive poly(methoxyoligo(ethylene glycol) norbornenyl esters) block copolymers in D2O were investigated by Small Angle Neutron Scattering (SANS). Each block is a comb-like polymer with a polynorbornene (PNB) backbone and oligo ethylene glycol (OEG) side chains (one side chain per NB monomer). The chemical formula of the block copolymer is (OEG3NB)79-(OEG6.6NB)67, where subscripts represent the degree of polymerization (DP) of OEG and NB in each block The polymer concentration was fixed at 2.0 wt % and the structural changes were investigated over a temperature range between 25 C and 68 C. It was found that at room temperature polymers associate to form micelles with a spherical core formed by the block (OEG3NB)79 and corona formed by the block (OEG6.6NB)67 and that the shape of the polymer in the corona could be described by the form factor of rigid cylinders. At elevated temperatures, the aggregation number increases and the micelles become more compact. At temperatures round the cloud point temperature (CPT) T = 60 C a correlation peak started to appear and became pronounced at 68 C due to the formation of a partially ordered structure with a correlation length ∼ 349

  9. Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs.

    Science.gov (United States)

    Yang, Chuan; Liu, Shao Qiong; Venkataraman, Shrinivas; Gao, Shu Jun; Ke, Xiyu; Chia, Xin Tian; Hedrick, James L; Yang, Yi Yan

    2015-06-28

    Amphiphilic polycarbonate/PEG copolymer with a star-like architecture was designed to facilitate a unique supramolecular transformation of micelles to vesicles in aqueous solution for the efficient delivery of anticancer drugs. The star-shaped amphipilic block copolymer was synthesized by initiating the ring-opening polymerization of trimethylene carbonate (TMC) from methyl cholate through a combination of metal-free organo-catalytic living ring-opening polymerization and post-polymerization chain-end derivatization strategies. Subsequently, the self-assembly of the star-like polymer in aqueous solution into nanosized vesicles for anti-cancer drug delivery was studied. DOX was physically encapsulated into vesicles by dialysis and drug loading level was significant (22.5% in weight) for DOX. Importantly, DOX-loaded nanoparticles self-assembled from the star-like copolymer exhibited greater kinetic stability and higher DOX loading capacity than micelles prepared from cholesterol-initiated diblock analogue. The advantageous disparity is believed to be due to the transformation of micelles (diblock copolymer) to vesicles (star-like block copolymer) that possess greater core space for drug loading as well as the ability of such supramolecular structures to encapsulate DOX. DOX-loaded vesicles effectively inhibited the proliferation of 4T1, MDA-MB-231 and BT-474 cells, with IC50 values of 10, 1.5 and 1.0mg/L, respectively. DOX-loaded vesicles injected into 4T1 tumor-bearing mice exhibited enhanced accumulation in tumor tissue due to the enhanced permeation and retention (EPR) effect. Importantly, DOX-loaded vesicles demonstrated greater tumor growth inhibition than free DOX without causing significant body weight loss or cardiotoxicity. The unique ability of the star-like copolymer emanating from the methyl cholate core provided the requisite modification in the block copolymer interfacial curvature to generate vesicles of high loading capacity for DOX with significant

  10. Micelles and gels of oxyethylene-oxybutylene diblock copolymers in aqueous solution: The effect of oxyethylene-block length

    DEFF Research Database (Denmark)

    Derici, L.; Ledger, S.; Mai, S.M.;

    1999-01-01

    Block copolymer E(90)B(10) (E = oxyethylene, B = oxybutylene) was synthesised and characterised by gel permeation chromatography and (13)C NMR spectroscopy. Dynamic light scattering (DLS) and static light scattering (SLS) were used to characterise the micelles in solution (both in water and in...... of the E blocks occurred at high concentration (greater than or equal to 70 wt.% copolymer). By combining the present and published results, a comparison was made of the micelle and gel properties of copolymers with the same B-block length but different E-block lengths, i.e., E(90)B(10), E(40)B(10...... water in the micelle core. Moderately concentrated solutions of copolymer E(90)B(10) were studied in the gel state by small-angle X-ray scattering (SAXS) in tandem with rheology (oscillatory shear). Values for the dynamic elastic modulus (G') of the gels significantly exceeded 10(4) Pa across the range...

  11. Novel pH or thermosensitive block copolymers for triggered drug-delivery systems

    OpenAIRE

    Jérôme, Christine

    2007-01-01

    Over the last decade, polymer micelles and nanoparticles have attracted an increasing interest as efficient drug delivery systems. Polymer micelles from amphiphilic block copolymers are supramolecular core-shell type assemblies of some tens of nanometers in diameter. They are highly stable in aqueous solution because of their low intrinsic critical micelle concentration, which prevents their dissociation upon dilution in the blood stream after intravenous injection. The combination of poly(e...

  12. Synthetic routes toward functional block copolymers and bioconjugates via RAFT polymerization

    OpenAIRE

    Wiss, Kerstin T.

    2010-01-01

    Synthetic Routes toward Functional Block Copolymers and Bioconjugates via RAFT PolymerizationrnSynthesewege für funktionelle Blockcopolymere und Biohybride über RAFT PolymerisationrnDissertation von Dipl.-Chem. Kerstin T. WissrnIm Rahmen dieser Arbeit wurden effiziente Methoden für die Funktionalisierung beider Polymerkettenenden für Polymer- und Bioanbindung von Polymeren entwickelt, die mittels „Reversible Addition-Fragmentation Chain Transfer“ (RAFT) Polymerisation hergestellt wurden. Zu d...

  13. Synthesis of (meth)acrylate block copolymers by ligated anionic polymerization

    Czech Academy of Sciences Publication Activity Database

    Vlček, Petr; Čadová, Eva; Janata, Miroslav; Látalová, Petra; Toman, Luděk; Kříž, Jaroslav; Kurková, Dana

    2006-01-01

    Roč. 240, č. 1 (2006), s. 141-150. ISSN 1022-1360. [International Symposium on Ionic Polymerization. Goa, 23.10.2005-28.10.2005] R&D Projects: GA MŠk 1P05ME753 Institutional research plan: CEZ:AV0Z40500505 Keywords : anionic polymerization * block copolymers * ester-enolates Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.913, year: 2005

  14. Intracellular Trafficking of Polyamidoamine – Polyethylene Glycol Block Copolymers in DNA Delivery

    OpenAIRE

    Bonner, Daniel K.; Leung, Cheuk; Chen-Liang, Jane; Chingozha, Loice; Langer, Robert; Hammond, Paula T.

    2011-01-01

    The delivery of nucleic acids has the potential to revolutionize medicine by allowing previously untreatable diseases to be clinically addressed. Viral delivery systems have shown immunogenicity and toxicity dangers, but synthetic vectors have lagged in transfection efficiency. Previously, we have developed a modular, linear-dendritic block copolymer architecture with high gene transfection efficiency compared to commercial standards. This rationally designed system makes use of a cationic de...

  15. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    OpenAIRE

    D.W. Grainger; S. W. Kim; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end-groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted t...

  16. Block copolymer blends and solutions: from periodic nanostructures to bicontinuous micro-emulsions

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Tuzar, Zdeněk; Černoch, Peter; Nallet, F.; Diat, O.

    Stellenbosch : UNESCO Associated Centre for Macromolecules and Materials, University of Stellenbosch, 2005. Session 6, I. [Workshop on Advanced Materials (WAM III) focusing on Nanostructured Advanced Materials. 5.9.2005-8.9.2005, Stellenbosch] R&D Projects: GA ČR GESON/03/E001; GA AV ČR IAA4050403 Keywords : block copolymer films * nanostructures * light and neutron scattering Subject RIV: CD - Macromolecular Chemistry

  17. Vertically oriented hexagonal mesoporous zirconia thin films by block copolymer templating

    OpenAIRE

    Miko, Annamaria ; Demirel, A. Levent ; Somer, Mehmet

    2012-01-01

    We report the synthesis of vertically oriented, long-range ordered hexagonal mesoporous zirconia thin ?lms. The orientation of hexagonally ordered cylindrical mesopores in thin ?lms was effectively controlled by taking advantage of the temperature dependent hydrophobicity of the templating block copolymer PEO–PPO–PEO. Vertical orientation was obtained when temperature was 30 C or above throughout the process. Dehydration and enhanced chemical incompatibility between the PEO and PPO b...

  18. Phase diagram of selectively cross-linked block copolymers shows chemically microstructured gel

    OpenAIRE

    von der Heydt, Alice; Zippelius, Annette

    2014-01-01

    We study analytically the intricate phase behavior of cross-linked $AB$ diblock copolymer melts, which can undergo two main phase transitions due to quenched random constraints: Gelation, i.e., spatially random localization of polymers forming a system-spanning cluster, is driven by increasing the number parameter $\\mu$ of irreversible, type-selective cross-links between random pairs of $A$ blocks. Self-assembly into a periodic pattern of $A$/$B$-rich microdomains (microphase separation) is c...

  19. Tunable Mesoporous Bragg Reflectors Based on Block-Copolymer Self-Assembly

    OpenAIRE

    Guldin, S.; Kolle, M.; Stefik, M.; Langford, R; Eder, D.; Wiesner, U.; Steiner, U.

    2011-01-01

    Mesoporous Bragg reflectors are a promising materials platform for photovoltaics, light emission, and sensing. A fast and versatile fabrication route that relies on the self-assembly of the block copolymer poly(isoprene-b-ethylene oxide) in combination with simple sol-gel chemistry is reported. The method allows extended control over porosity and pore size in the resulting inorganic material and results in high-quality optical elements.

  20. Structural and Mechanical Hysteresis at the Order-Order Transition of Block Copolymer Micellar Crystals

    OpenAIRE

    LaFollette, Theresa A.; Lynn M. Walker Walker

    2011-01-01

    Concentrated solutions of a water-soluble block copolymer (PEO)20-(PPO)70-(PEO)20 show a thermoreversible transition from a liquid to a gel. Over a range of concentration there also exists an order-order transition (OOT) between cubically-packed spherical micelles and hexagonally-packed cylindrical micelles. This OOT displays a hysteresis between the heating and cooling transitions that is observed at both the macroscale through rheology and nanoscale through small angle neutron scattering (S...

  1. Aggregate of Amphiphilic Block Copolymer as a Pseudo-Stationary Phase in Capillary Electrophoresis

    OpenAIRE

    Nakamura, Tohru; OHKI, Akira; Mishiro, Masaki; Tsuyashima, Osamu; Maeda, Shigeru; ナカムラ, トオル; オオキ, アキラ; ミシロ, マサキ; ツヤシマ, オサム; マエダ, シゲル; 中村, 透; 大木, 章; 艶島, 修; 前田, 滋

    1999-01-01

    The use of an aggregate of amphiphilic block copolymer 1, which consists of poly[(N-acetylimino)ethylene] and poly[(N-pentanoylimino)ethylene], for a pseudo-stationary phase in capillary electrophoresis has been examined. From gel-filtration chromatography, the aggregate from 1 (1-AG) was found to incorporate phenol. When the running solution contains 1-AG and sodium dodecyl sulfate (SDS), the electrophoretic mobility becomes nearly zero. Thus, it is found that when 1-AG and SDS are added to ...

  2. Precise Control over the Rheological Behavior of Associating Stimuli-Responsive Block Copolymer Gels

    OpenAIRE

    Jérémy Brassinne; Flanco Zhuge; Charles-André Fustin; Jean-François Gohy

    2015-01-01

    “Smart” materials have considerably evolved over the last few years for specific applications. They rely on intelligent macromolecules or (supra-)molecular motifs to adapt their structure and properties in response to external triggers. Here, a supramolecular stimuli-responsive polymer gel is constructed from heterotelechelic double hydrophilic block copolymers that incorporate thermo-responsive sequences. These macromolecular building units are synthesized via a three-step controlled radical...

  3. Connecting Molecular Dynamics Simulations and Fluids Density Functional Theory of Block Copolymers

    Science.gov (United States)

    Hall, Lisa

    Increased understanding and precise control over the nanoscale structure and dynamics of microphase separated block copolymers would advance development of mechanically robust but conductive materials for battery electrolytes, among other applications. Both coarse-grained molecular dynamics (MD) simulations and fluids (classical) density functional theory (fDFT) can capture the microphase separation of block copolymers, using similar monomer-based chain models and including local packing effects. Equilibrium free energies of various microphases are readily accessible from fDFT, which allows us to efficiently determine the equilibrium nanostructure over a large parameter space. Meanwhile, MD allows us to visualize specific polymer conformations in 3D over time and to calculate dynamic properties. The fDFT density profiles are used to initialize the MD simulations; this ensures the MD proceeds in the appropriate microphase separated state rather than in a metastable structure (useful especially for nonlamellar structures). The simulations equilibrate more quickly than simulations initialized with a random state, which is significant especially for long chains. We apply these methods to study the interfacial behavior and microphase separated structure of diblock and tapered block copolymers. Tapered copolymers consist of pure A and B monomer blocks on the ends separated by a tapered region that smoothly varies from A to B (or from B to A for an inverse taper). Intuitively, tapering increases the segregation strength required for the material to microphase separate and increases the width of the interfacial region. Increasing normal taper length yields a lower domain spacing and increased polymer mobility, while larger inverse tapers correspond to even lower domain spacing but decreased mobility. Thus the changes in dynamics with tapering cannot be explained by mapping to a diblock system at an adjusted effective segregation strength. This material is based upon work

  4. Contribution of orientational effects into radiation-chemical properties of segregated block copolymers

    International Nuclear Information System (INIS)

    Model of radiolysis of microphase-separated block copolymers of PS with PB is proposed. According this scheme the radiation-chemical yields of paramagnetic centres and crosslinks in PB domains differ from those for the PB homopolymer by the value proportional to the fraction of ordered chain segments. This orientational small-scale order arises as a result of the deformation of chains in a domain in the direction perpendicular to the interphase

  5. Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk

    OpenAIRE

    Matsushita, Y; Iwata, H; Asari, T; Uchida, T.; ten Brinke, G.; Takano, A

    2004-01-01

    Chain elongation suppression of cyclic block copolymers in microphase-separated bulk was determined quantitatively. Solvent-cast and annealed films are confirmed to show alternating lamellar structure and their microdomain spacing D increases with increasing total molecular weight M according to the relationship Dproportional toM(0.59), which agrees quite consistently with the theoretically predicted power law, i.e., Dproportional toM(3/5). This result is in contrast to the well-established i...

  6. CdS-containing nano-assemblies of double hydrophilic block copolymers in water

    Czech Academy of Sciences Publication Activity Database

    Uchman, M.; Procházka, K.; Gatsouli, K.; Pispas, S.; Špírková, Milena

    2011-01-01

    Roč. 289, č. 9 (2011), s. 1045-1053. ISSN 0303-402X R&D Projects: GA ČR GCP205/11/J043; GA ČR GAP208/10/0353 Institutional research plan: CEZ:AV0Z40500505 Keywords : double hydrophilic block copolymers * polymer self-assembly * light scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.331, year: 2011

  7. Single-molecule protein arrays enabled by scanning probe block copolymer lithography

    OpenAIRE

    Chai, Jinan; Wong, Lu Shin; Giam, Louise; Mirkin, Chad A.

    2011-01-01

    The ability to control the placement of individual protein molecules on surfaces could enable advances in a wide range of areas, from the development of nanoscale biomolecular devices to fundamental studies in cell biology. Such control, however, remains a challenge in nanobiotechnology due to the limitations of current lithographic techniques. Herein we report an approach that combines scanning probe block copolymer lithography with site-selective immobilization strategies to create arrays o...

  8. Selective gas transfer through binary polymeric systems based on block-copolymers.

    Science.gov (United States)

    Beckman, I N; Teplyakov, V V

    2015-08-01

    Evaluation of several versions of phenomenological theory of gas permeability in selective polymeric membranes is presented, along with the appropriate experimental methods for verification of these versions. The main focus is on a description of stationary mass transfer across membranes (films) containing dispersion inclusions of various shapes of one polymer in a matrix of another. Considering heterogeneous media as a membrane material, it was assumed that diffusion and sorption properties of inclusions are different from those of the dispersing medium. The problem of choosing optimal shape of inclusions is evaluated from the point of view of targeted permeability and selectivity of a membrane with respect to gases. To confirm this theoretical approach, the experimental results of the studies of diffusion (permeability) of permanent gases in polymeric membranes of different structures were used. The target gases included noble gases, hydrogen, nitrogen, oxygen, CO2, and methane. The target polymers included glassy polyvinyltrimethylsilane (PVTMS, T(gl)=155-180 °C), rubberlike polydimethylsiloxane (PDMS, T(gl)=-120 °C), and two-phase block-copolymers based on these materials within a wide range of composition, including the region of phase inversion. In addition, available experimental literature data on gas permeation parameters for polyarylat-polysiloxane, polysulfon-polysiloxane, and polycarbonate-polysiloxane block-copolymers are utilized. In order to describe the stationary gas permeability for two-phase systems (from diluted dispersion of one polymer in another to concentrated dispersion and complete phase inversion) the empiric approaches based on modified Maxwell equations are offered. The requirements for two-phase systems with high permeability and selectivity parameters for gas separation are identified. The permeability parameters are predicted for C1-C4 hydrocarbons in block-copolymers based on PDMS dispersion in PVTMS, phase inversion, and PVTMS

  9. Holographic Gratings and Data Storage in Azobenzene-Containing Block Copolymers and Molecular Glasses

    Science.gov (United States)

    Audorff, Hubert; Kreger, Klaus; Walker, Roland; Haarer, Dietrich; Kador, Lothar; Schmidt, Hans-Werner

    This review covers synthesis, materials development, and photophysics of azobenzene-containing block copolymers as potential media for reversible volume holographic data storage. For high-density holographic data storage, volume gratings must be inscribed in millimeter-thick samples to achieve efficient angle multiplexing. It is demonstrated that block copolymers with azobenzene side-groups in the minority block develop no detrimental surface relief structures and exhibit superior performance regarding volume gratings, compared to homopolymers and statistical copolymers. Several material concepts for optimizing the refractive index modulation and the stability of volume gratings are presented. Stabilities of more than 2 years were achieved. Most important is the development of polymer blends comprising the azobenzene-containing block copolymer and an optically transparent homopolymer. This enables the preparation of millimeter-thick samples with the required optical density of ˜ 0. 7 at the writing wavelength by conventional injection molding techniques. The inscription of up to 200 holograms at the same lateral position was demonstrated. In addition, more than 1,000 write/erase cycles can be performed. This is the first time that the inscription and erasure of the long-term stable angle-multiplexed volume gratings in a rewritable polymeric medium have been achieved by purely optical means. A second important application for azobenzene-containing materials is the controlled preparation of surface relief structures. It is demonstrated that azobenzene-containing molecular glasses are an ideal class for efficient formation of surface relief gratings (SRGs) with amplitude heights of more than 600 nm. Clear relationships can be established between the chemical structure of the molecules and the behavior of SRG formation. All results are in agreement with the gradient force model by Kumar et al. The surface patterns are stable enough to be transferred to a polymer

  10. Use of Superparamagnetic Nanoparticle/Block Copolymer Electrostatic Complexes as Contrast Agents in Magnetic Resonance Imaging

    OpenAIRE

    Berret, Jean-Francois; Cartier, Regis

    2007-01-01

    During the past years we have investigated the complexation between nanocolloids and oppositely charged polymers. The nanocolloids examined were ionic surfactant micelles and inorganic oxide nanoparticles. For the polymers, we used homopolyelectrolytes and block copolymers with linear and comb architectures. In general, the attractive interactions between oppositely charged species are strong and as such, the simple mixing of solutions containing dispersed constituents yield to a precipitatio...

  11. Ultra-cold neutron interaction with the copolymer block of polystyrene-polybutadiene-polystyrene type

    International Nuclear Information System (INIS)

    An ultra-cold neutron (UCN) spectrometer has been used to study dependences of the total interaction cross sections on the UCN wave length (Σsub(t)(lambda)) with copolymer block of polystyrene-polybutadiene-polystyrene type at room temperature and 99 K. Investigation into dependences of the UCN total interaction cross sections is a considerably informative method in studying the structure and dynamics of substances, possessing an ordered epimolecular structure

  12. NMR study of thermoresponsive micelles of amphiphilic block copolymers in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

    Zurich: Swiss Federal Institute of Technology, 2014. s. 387. ISBN 978-3-906031-54-5. [Euromar 2014. Magnetic Resonance Conference. 29.06.2014-03.07.2014, Zürich] R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : thermoresponsive block copolymer * poly(N-isopropylacrylamide) * poly(ethylene glycol) Subject RIV: CD - Macromolecular Chemistry

  13. Block copolymer self-assembly and co-assembly : shape function and application

    OpenAIRE

    Li, F

    2009-01-01

    Amphiphilic block copolymers can, in selective solvents such as water, assemble into various shapes and architectures. Among those, polymer vesicles, polymer micelles and polymer fibers are very popular structures in current nanotechnology. These objects each have their own particular properties and can serve as containers or templates for different nanotechnological applications. Polymer vesicles, for example, can encapsulate both hydrophobic and hydrophilic molecules, and are therefore cons...

  14. Preparation of amphiphilic block copolymer containing triazene moieties and fluorescence study

    Indian Academy of Sciences (India)

    Emil C Buruiana; Andreea L Chibac; Violeta Melinte; Tinca Buruiana

    2013-01-01

    The present study describes the synthesis via microwave accelerated reversible additionfragmentation chain transfer (RAFT) polymerization of an amphiphilic block copolymer poly(acrylic acid)-b-poly(dodecylacrylamide-co-1-(phenyl)-3-(2-methacryloyloxyethyl carbamoyloxyethyl)-3-methyltriazene-1) [PAA-b-(PDA-co-PUMA-T)]. The structure and the chemical composition of the block copolymer were confirmed by spectral/thermal analysis. The photoreactivity of the triazene sequences from PAA-b-(PDA-co-PUMA-T) was quantified by UV/vis irradiation in chloroform/dimethylformamide solutions and in thin film, indicating that the solvent polarity modifies with an order of magnitude the rate constant values. The lower rate constant in film state (film = 1.3 × 10−3 s-1), shows that the higher mobility of polymeric chains in solution allow a more rapid orientation, favourable to the triazene bond cleavage. The capability of block copolymer to form micelles in aqueous environment and implicitly, its critical micelle concentration (CMC) was evidenced through fluorescence measurements using pyrene probe (10-6 M), the CMC value being of 4.64 × 10−3 g L-1 PAA--(PDA--PUMA-T) (3.27 × 10−7 M). Experiments of fluorescence quenching with various metal cations (UO$^{2+}_{2}$, Fe2+, Fe3+, Ni2+, Cu2+, Co2+, Pb2+ and Hg2+) suggested that such a block copolymer could find applications as fluorescence-based chemosensor for the detection of iron cations in homogeneous organic solutions or aqueous environments by thin films.

  15. Electrochemical and bioelectrocatalytical properties of novel block-copolymers containing interacting ferrocenyl units

    OpenAIRE

    Garcia Armada, Maria del Pilar; Losada del Barrio, Jose; Lopez Villanueva, F.J.; H. Frey; Alonso Garrido, Beatriz; Casado Santana, Carmen M.

    2008-01-01

    The electrochemical characterization of three different polystyrene-b-polybutadiene block copolymers functionalized with ferrocenyl units electronically communicated, PSm-PBn(HSiMeFc2)p where m=615, n=53, p=39 (1), m=375, n=92, p=76 (2) and m=455, n=204, p=170 (3), has been carried out both in solution and electrochemically deposited onto platinum electrodes. The bioelectrocatalytical properties of electrodes modified with the polymers in the nicotinamide dinucleotide (NADH) and glucose oxida...

  16. Novel architecture design of block copolymers of ethylene glycol methyl ether methacrylate and carboxybetaine acrylamide

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Hasan, E.; Brynda, Eduard; Houska, Milan; Sedláková, Zdeňka; Bologna Alles, A.; Huck, W.

    Praha : Institute of Macromolecular Chemistry, 2009. s. 111. ISBN 978-80-85009-59-0. [Prague Meetings on Macromolecules /73./ New Frontiers in Macromolecular Science: From Macromolecular Concepts of Living Matter to Polymers for Better Quality of Life. 05.07.2009-09.07.2009, Prague] R&D Projects: GA AV ČR KAN200670701 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymers Subject RIV: CD - Macromolecular Chemistry

  17. Photoresponsive Azopolyester–PMMA Block Copolymers Obtained by Combination of ATRP, Polycondensation, and “Click” Chemistry

    DEFF Research Database (Denmark)

    Berges, Cristina; Javakhishvili, Irakli; Hvilsted, Søren; Sánchez, Carlos; Alcalá, Rafael

    2012-01-01

    Novel azobenzene‐containing block copolymers (BCs) with a polyester block bearing azobenzene moieties in the side chain and a poly (methyl methacrylate) (PMMA) block have been synthesized by the combination of atom transfer radical polymerization (ATRP), polycondensation, and “click” chemistry. Two...

  18. Toughening of epoxies based on self-assembly of nano-sized amphiphilic block copolymer micelles

    Science.gov (United States)

    Liu, Jia

    As a part of a larger effort towards the fundamental understanding of mechanical behaviors of polymers toughened by nanoparticles, this dissertation focuses on the structure-property relationship of epoxies modified with nano-sized poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer (BCP) micelle particles. The amphiphilic BCP toughener was incorporated into a liquid epoxy resin and self-assembled into well-dispersed 15 nm spherical micelle particles. The nano-sized BCP, at 5 wt% loading, can significantly improve the fracture toughness of epoxy (ca. 180% improvement) without reducing modulus at room temperature and exhibits only a slight drop (ca. 5°C) in glass transition temperature (Tg). The toughening mechanisms were found to be BCP micelle nanoparticle cavitation, followed by matrix shear banding, which mainly accounted for the observed remarkable toughening effect. The unexpected "nano-cavitation" phenomenon cannot be predicted by existing physical models. The plausible causes for the observed nano-scale cavitation and other mechanical behaviors may include the unique structural characteristics of BCP micelles and the influence from the surrounding epoxy network, which is significantly modified by the epoxy-miscible PEO block. Other mechanisms, such as crack tip blunting, may also play a role in the toughening. Structure-property relationships of this nano-domain modified polymer are discussed. In addition, other important factors, such as strain rate dependence and matrix crosslink density effect on toughening, have been investigated. This BCP toughening approach and conventional rubber toughening techniques are compared. Insights on the decoupling of modulus, toughness, and Tg for designing high performance thermosetting materials with desirable physical and mechanical properties are discussed.

  19. Selective directed self-assembly of coexisting morphologies using block copolymer blends

    Science.gov (United States)

    Stein, A.; Wright, G.; Yager, K. G.; Doerk, G. S.; Black, C. T.

    2016-01-01

    Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. Here we expand on traditional DSA chemical patterning. A blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This is in contrast to the typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist. PMID:27480327

  20. Amphiphilic Spider Silk-Like Block Copolymers with Tunable Physical Properties and Morphology for Biomedical Applications

    Science.gov (United States)

    Huang, Wenwen; Krishnaji, Sreevidhya; Kaplan, David; Cebe, Peggy

    2013-03-01

    Silk-based materials are important candidates for biomedical applications because of their excellent biocompatibility and biodegradability. To generate silk amphiphilic biopolymers with potential use in guided tissue repair and drug delivery, a novel family of spider silk-like block copolymers was synthesized by recombinant DNA technology. Block copolymer thermal properties, structural conformations, protein-water interactions, and self-assembly morphologies were studied with respect to well controlled protein amino acid sequences. A theoretical model was used to predict the heat capacity of the protein and protein-water complex. Using thermal analysis, two glass transitions were observed: Tg1 is related to conformational changes caused by bound water removal, while Tg2 (>Tg1) is the glass transition of dry protein. Real-time infrared spectroscopy and X-ray diffraction confirmed that different secondary structural changes occur during the two Tg relaxations. Using scanning electron microscopy, fibrillar networks and hollow vesicles are observed, depending on protein block copolymer sequence. This study provides a deeper understanding of the relationship between protein physical properties and amino acid sequence, with implications for design of other protein-based materials. Support was provided from the NSF CBET-0828028 and the MRI Program under DMR-0520655 for thermal analysis instrumentation.

  1. Triazene UV-triggered photogeneration of silver/gold nanoparticles in block copolymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Melinte, Violeta; Chibac, Andreea; Buruiana, Tinca; Hitruc, Gabriela; Buruiana, Emil C., E-mail: emilbur@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, Polyaddition and Photochemistry Department (Romania)

    2015-10-15

    This article describes an attractive way to in situ create noble metal nanoparticles in block copolymer matrixes through the UV-triggered photodecomposition of the photolabile triazene units without the use of any conventional reducing agent. The poly(isodecyl methacrylate-co-triazene urethane methacrylate) random copolymer containing pendent photocleavable triazene junctions (COP-1) was synthesized under RAFT conditions and subsequently employed as macroinitiator to obtain a block copolymer, namely poly(isodecyl methacrylate-co-triazene urethane methacrylate)-block-poly(acrylic acid) (COP-2). The photogeneration of silver/gold metal nanoparticles (NPs) from noble metal precursors (1 wt% AgNO{sub 3} or AuBr{sub 3} metal salts) induced through the UV decomposition of triazene units with the formation of some radical active species was monitored in solution and thin films. The in situ growth of Ag/Au nanostructures into polymer matrixes for which the light is a key element has been confirmed by UV spectroscopy and TEM analysis. The TEM images allowed the visualization of the silver NPs (sizes of 4–16 nm in COP-1 and of 2–6 nm in COP-2) as well as of the gold NPs (sizes between 10 and 20 nm in COP-1 and from 15 to 25 nm in COP-2), which are mainly spherical in shape, even though there is some triangular or hexagonal gold nanoparticles.

  2. Electrostatic self-assembly in polyelectrolyte-neutral block copolymers and oppositely charged surfactant solutions

    International Nuclear Information System (INIS)

    We report on small-angle neutron scattering (SANS) of colloidal complexes resulting from the electrostatic self-assembly of polyelectrolyte-neutral copolymers and oppositely charged surfactants. The polymers are double hydrophilic block copolymers of low molecular weight (between 5000 and 50 000 g/mol). One block is a polyelectrolyte chain, which can be either positively or negatively charged, whereas the second block is neutral and in good solvent conditions. In aqueous solutions, surfactants with an opposite charge to that of the polyelectrolyte interact strongly with these copolymers. The two species associate into stable 100 nm-colloidal complexes which exhibit a core-shell microstructure. For different polymer/surfactant couples, we have shown that the core is constituted from densely packed surfactant micelles connected by the polyelectrolyte chains. The outer part of the complex is a corona formed by the neutral soluble chains. Using a model of aggregation based on a Monte-Carlo algorithm, we have simulated the internal structure of the aggregates. The model assumes spherical cages containing one to several hundreds of micelles in a closely packed state. The agreement between the model and the data is remarkable

  3. Gel formation in a mixture of a block copolymer and a nematic liquid crystal.

    Science.gov (United States)

    Khazimullin, Maxim; Müller, Thomas; Messlinger, Stephan; Rehberg, Ingo; Schöpf, Wolfgang; Krekhov, Alexei; Pettau, Robin; Kreger, Klaus; Schmidt, Hans-Werner

    2011-08-01

    The viscoelastic properties of a binary mixture of a mesogenic side-chain block copolymer in a low molecular weight nematic liquid crystal are studied for mass concentrations ranging from the diluted regime up to a liquid crystalline gel state at about 3%. In the gel state, the system does not flow, exhibits a polydomain structure on a microscopic level, and strongly scatters light. Below the gelation point, the system is homogeneous and behaves like a usual nematic, so the continuum theory of liquid crystals can be applied for interpreting the experimental data. Using the dynamic Fréedericksz transition technique, the dependence of the splay elastic constant and the rotational viscosity on the polymer concentration have been obtained. Comparing the dynamic behavior of block copolymer solutions with the respective homopolymer solutions reveals that, above a mass concentration of 1%, self-assembling of the block copolymer chain segments in clusters occurred, resulting in a gel state at higher concentrations. The effective cluster size is estimated as a function of the concentration, and a scaling-law behavior near the sol-gel transition is confirmed. This technique may serve as an alternative method for determining the gelation point. PMID:21929007

  4. Gel formation in a mixture of a block copolymer and a nematic liquid crystal

    Science.gov (United States)

    Khazimullin, Maxim; Müller, Thomas; Messlinger, Stephan; Rehberg, Ingo; Schöpf, Wolfgang; Krekhov, Alexei; Pettau, Robin; Kreger, Klaus; Schmidt, Hans-Werner

    2011-08-01

    The viscoelastic properties of a binary mixture of a mesogenic side-chain block copolymer in a low molecular weight nematic liquid crystal are studied for mass concentrations ranging from the diluted regime up to a liquid crystalline gel state at about 3%. In the gel state, the system does not flow, exhibits a polydomain structure on a microscopic level, and strongly scatters light. Below the gelation point, the system is homogeneous and behaves like a usual nematic, so the continuum theory of liquid crystals can be applied for interpreting the experimental data. Using the dynamic Fréedericksz transition technique, the dependence of the splay elastic constant and the rotational viscosity on the polymer concentration have been obtained. Comparing the dynamic behavior of block copolymer solutions with the respective homopolymer solutions reveals that, above a mass concentration of 1%, self-assembling of the block copolymer chain segments in clusters occurred, resulting in a gel state at higher concentrations. The effective cluster size is estimated as a function of the concentration, and a scaling-law behavior near the sol-gel transition is confirmed. This technique may serve as an alternative method for determining the gelation point.

  5. Nanofabrication of Block Copolymers of PDMS/Polyamide having Trichlorogermyl Pendant Using LbL Technique

    International Nuclear Information System (INIS)

    Block copolymers (AB)x type of aminopropyl-terminated poly(dimethylsiloxane) (NH2- PDMS) and polyamides trichlorogermyl pendant group were prepared by a solution phase one pot polycondensation method. The prepared block copolymers were assembled with polyethylene-alt- (maleic) anhydride (PEMA) as multilayered thin film assembly through covalently linked Layer by Layer (LbL) technique using dipping method. The prepared thin films had thickness in the range of 15 to 20 nm as measured on an ellipsometers. In the systems where quartz was used as substrate, film growth after each deposition was monitored through UV-Vis spectrophotometer, which substantiated the multilayer film build-up. Atomic Force Microscopic (AFM) images showed homogeneous and robust film, which were strong enough to endure the force of 400 nN. As the block copolymers are thermally stable and have the capacity to absorb water, so their prepared robust ultra-thin films can show potential of thermally resistant nano thin films, protective hydrophilic coatings in addition to separation membranes. (author)

  6. Triazene UV-triggered photogeneration of silver/gold nanoparticles in block copolymer templates

    International Nuclear Information System (INIS)

    This article describes an attractive way to in situ create noble metal nanoparticles in block copolymer matrixes through the UV-triggered photodecomposition of the photolabile triazene units without the use of any conventional reducing agent. The poly(isodecyl methacrylate-co-triazene urethane methacrylate) random copolymer containing pendent photocleavable triazene junctions (COP-1) was synthesized under RAFT conditions and subsequently employed as macroinitiator to obtain a block copolymer, namely poly(isodecyl methacrylate-co-triazene urethane methacrylate)-block-poly(acrylic acid) (COP-2). The photogeneration of silver/gold metal nanoparticles (NPs) from noble metal precursors (1 wt% AgNO3 or AuBr3 metal salts) induced through the UV decomposition of triazene units with the formation of some radical active species was monitored in solution and thin films. The in situ growth of Ag/Au nanostructures into polymer matrixes for which the light is a key element has been confirmed by UV spectroscopy and TEM analysis. The TEM images allowed the visualization of the silver NPs (sizes of 4–16 nm in COP-1 and of 2–6 nm in COP-2) as well as of the gold NPs (sizes between 10 and 20 nm in COP-1 and from 15 to 25 nm in COP-2), which are mainly spherical in shape, even though there is some triangular or hexagonal gold nanoparticles

  7. Controlling the Morphology of Side Chain Liquid Crystalline Block Copolymer Thin Films through Variations in Liquid Crystalline Content

    OpenAIRE

    Verploegen, Eric; Zhang, Tejia; Jung, Yeon Sik; Ross, Caroline; Hammond, Paula T.

    2008-01-01

    In this paper we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the...

  8. Synthesis, micellar properties and application of amphiphilic linear block copolymers with different microstructure but same molecular weight

    OpenAIRE

    Schmitz, Christof Jan Wilhelm

    2009-01-01

    This dissertation is concerned with the synthesis and micellisation behaviour of linear block copolymers based on methacrylates by means of the modern controlled radical polymerisation technique, namely the atom transfer radical polymerisation (ATRP). The objective was the synthesis of linear block copolymers with different microstructure but same molecular weight. The chosen synthesis strategy should be applicable for various monomer pairs with different polarities and should include the use...

  9. Nanoporous materials from stable and metastable structures of 1,2-PB-b-PDMS block copolymers

    DEFF Research Database (Denmark)

    Schulte, Lars; Grydgaard, Anne; Jakobsen, Mathilde R.;

    2011-01-01

    Experimental procedures used at the preparation and characterization stages of nanoporous materials (NPM) from 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS) block copolymers are presented. The NPM were obtained from self-assembled block copolymers after firstly cross-linking 1,2-PB (the...... characterization of the materials at different stages of preparation includes gravimetry, infrared spectroscopy, small angle x-ray scattering, electron microscopy and isothermal nitrogen adsorption experiments....

  10. Neutron Reflection Studies on Lamellar Microphase-Separated Structures of Two-Component Block Copolymers with Composition Distribution

    International Nuclear Information System (INIS)

    Segmental distribution of polystyrene blocks in lamellar microphase-separated poly(styrene-block-2-vinylpyridine) (SP) with wide composition distribution was investigated by neutron reflectivity measurements using deuterium-labeled polymers. Block copolymers with wide composition distribution were produced by mixing three monodispersed parent block copolymers, which were synthesized by an anionic polymerization method to have the same total molecular weight but with different volume fractions. The block copolymer blends whose overall S/P ratio is 0.5/0.5 were found to form a uniform lamellar structure, where lamellae were highly oriented along the direction parallel to the film surface and the interfacial thickness was evaluated as 40 A. It was clarified that a shorter block chain in the microdomain is localized at the domain boundary, while a longer one has a peak at the center of microdomain in its segmental distribution profile

  11. Ultrasound responsive block copolymer micelle of poly(ethylene glycol)-poly(propylene glycol) obtained through click reaction.

    Science.gov (United States)

    Li, Fayong; Xie, Chuan; Cheng, Zhengang; Xia, Hesheng

    2016-05-01

    The well-defined amphiphilic poly(ethylene glycol)-block-poly(propylene glycol) copolymer containing 1, 2, 3-triazole moiety and multiple ester bonds (PEG-click-PPG) was prepared by click reaction strategy. The PEG-click-PPG copolymer can self-assemble into spherical micelles in aqueous solution. It is found that high intensity focused ultrasound (HIFU) can open the copolymer PEG-click-PPG micelles and trigger the release of the payload in the micelle. The multiple ester bonds introduced in the junction point of the copolymer chain through click reactions were cleaved under HIFU, and leads to the disruption of the copolymer micelle and fast release of loaded cargo. The click reaction provides a convenient way to construct ultrasound responsive copolymer micelles with weak bonds. PMID:26703197

  12. Cooperative catalysis with block copolymer micelles: A combinatorial approach

    KAUST Repository

    Bukhryakov, Konstantin V.

    2015-02-09

    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  13. Block Copolymer-Based Supramolecular Elastomers with High Extensibility and Large Stress Generation Capability

    Science.gov (United States)

    Noro, Atsushi; Hayashi, Mikihiro

    We prepared block copolymer-based supramolecular elastomers with high extensibility and large stress generation capability. Reversible addition fragmentation chain transfer polymerizations were conducted under normal pressure and high pressure to synthesize several large molecular weight polystyrene-b-[poly(butyl acrylate)-co-polyacrylamide]-b-polystyrene (S-Ba-S) block copolymers. Tensile tests revealed that the largest S-Ba-S with middle block molecular weight of 3140k achieved a breaking elongation of over 2000% with a maximum tensile stress of 3.6 MPa and a toughness of 28 MJ/m3 while the reference sample without any middle block hydrogen bonds, polystyrene-b-poly(butyl acrylate)-b-polystyrene with almost the same molecular weight, was merely viscous and not self-standing. Hence, incorporation of hydrogen bonds into a long soft middle block was found to be beneficial to attain high extensibility and large stress generation capability probably due to concerted combination of entropic changes and internal potential energy changes originaing from the dissociation of multiple hydrogen bonds by elongation. This work was supported by JSPS KAKENHI Grant Numbers 13J02357, 24685035, 15K13785, and 23655213 for M.H. and A.N. A.N. also expresses his gratitude for Tanaka Rubber Science & Technology Award by Enokagaku-Shinko Foundation, Japan.

  14. Meso-scale Modeling of Block Copolymers Self-Assembly in Casting Solutions for Membrane Manufacture

    KAUST Repository

    Moreno Chaparro, Nicolas

    2016-05-01

    Isoporous membranes manufactured from diblock copolymer are successfully produced at laboratory scale under controlled conditions. Because of the complex phenomena involved, membrane preparation requires trial and error methodologies to find the optimal conditions, leading to a considerable demand of resources. Experimental insights demonstrate that the self-assembly of the block copolymers in solution has an effect on the final membrane structure. Nevertheless, the complete understanding of these multi-scale phenomena is elusive. Herein we use the coarse-grained method Dissipative Particle Dynamics to study the self-assembly of block copolymers that are used for the preparation of the membranes. To simulate representative time and length scales, we introduce a framework for model reduction of polymer chain representations for dissipative particle dynamics, which preserves the properties governing the phase equilibria. We reduce the number of degrees of freedom by accounting for the correlation between beads in fine-grained models via power laws and the consistent scaling of the simulation parameters. The coarse-graining models are consistent with the experimental evidence, showing a morphological transition of the aggregates as the polymer concentration and solvent affinity change. We show that hexagonal packing of the micelles can occur in solution within different windows of polymer concentration depending on the solvent affinity. However, the shape and size dispersion of the micelles determine the characteristic arrangement. We describe the order of crew-cut micelles using a rigid-sphere approximation and propose different phase parameters that characterize the emergence of monodisperse-spherical micelles in solution. Additionally, we investigate the effect of blending asymmetric diblock copolymers (AB/AC) over the properties of the membranes. We observe that the co-assembly mechanism localizes the AC molecules at the interface of A and B domains, and induces

  15. Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization.

    Science.gov (United States)

    Haraguchi, Kazutoshi; Kubota, Kazuomi; Takada, Tetsuo; Mahara, Saori

    2014-06-01

    Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide): D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.g., polystyrene, polycarbonate, polypropylene, Ti, and glass), and the surface coating showed high protein repellency and a low contact angle for water, regardless of the substrate. The two opposing characteristics of high protein repellency and good substrate adhesion were achieved by the combined effects of the molecular architecture of the block copolymers, the high molecular weight, and the characteristics of each segment, that is, low protein adsorption capability of both segments and low glass transition temperature of the hydrophobic segment. Further, a polystyrene dish coated with the MDM block copolymer could be sterilized by γ-ray irradiation and used as a good substrate for a suspension cell culture that exhibits low cell adhesion and good cell growth. PMID:24773089

  16. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan

    2016-03-11

    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

  17. Hierarchical assembly of block copolymer micelles into reversible networks: MC simulations

    Science.gov (United States)

    Wang, Zilu; Dormidontova, Elena

    2015-03-01

    The rapid development of nanoscience has considerably expanded the range of building blocks for complex self-assembled nanostructure formation, which show great potential for numerous advanced applications. We apply Monte Carlo simulations to gain understanding of molecular mechanism of self-assembly of nanostructures formed by diblock copolymer micelles interconnected by means of metal-ligand complexation. These systems exhibit interesting chemical and mechanical stimuli-responsive behavior and possess two levels of self-assembly: 1) self-assembly of diblock copolymers into micelles and 2) reversible inter-micelle bridging by coordination bonding between metal ions and ligands attached to the corona of nanoparticles, which is responsible for the network viscoelastic properties. Using MC simulations we investigate the effect of metal-ligand complexation on diblock-copolymer micelle formation and vice versa. We analyze the extent of intra- and inter-micelle loops and bridges formed by metal-ligand complexation in relation to the degree of crosslinking and elastic properties of the network. The effect of polymer concentration, hydrophilic block length, metal to oligomer ratio and type of complexation (2:1 or 3:1) on equilibrium properties of reversible networks will be discussed.

  18. Small angle neutron scattering study of doxorubicin–surfactant complexes encapsulated in block copolymer micelles

    Indian Academy of Sciences (India)

    Jayita Bhattacharjee; Gunjan Verma; V K Aswal; P A Hassan

    2008-11-01

    Self-assembling behaviour of block copolymers and their ability to evade the immune system through polyethylene oxide stealth makes it an attractive candidate for drug encapsulation. Micelles formed by polyethylene oxide–polypropylene oxide–polyethylene oxide triblock copolymers (PEO–PPO–PEO), pluronic P123, have been employed for encapsulating the anti-cancer drug doxorubicin hydrochloride. The binding affinity of doxorubicin within the micelle carrier is enhanced through complex formation of drug and anionic surfactant, aerosol OT (AOT). Electrostatic binding of doxorubicin with negatively charged surfactants leads to the formation of hydrophobic drug–surfactant complexes. Surfactant-induced partitioning of the anti-cancer drug into nonpolar solvents such as chloroform is investigated. SANS measurements were performed on pluronic P123 mi-celles in the presence of drug–surfactant complex. No significant changes in the structure of the micelles are observed upon drug encapsulation. This demonstrates that surfactant–drug complexes can be encapsulated in block copolymer micelles without disrupting the structure of aggregates.

  19. Nanopatterning by large block copolymers for application in photonic devices (Conference Presentation)

    Science.gov (United States)

    Mokarian-Tabari, Parvaneh; Senthamaraikannan, Ramsankar; Collins, Timothy W.; Glynn, Colm; O'Dwyer, Colm; Morris, Michael

    2016-04-01

    The extensive benefits of the new generation of nanostructured surfaces is very promising for enhancing light absorption efficiency in photonic devices. However, the low throughput and the high cost of available technologies such as lithography for fabrication of nanostructures has proved to be a difficult technological hurdle for advanced manufacturing. In this research we present a solution based process based on high molecular weight block copolymer (BCP) nanolithography for fabrication of periodic structures on large areas of optical surfaces. Block copolymer self- assembly technique is a solution based process that offers an alternative route to produce highly ordered photonic crystal structures. BCPs forms nanodomains (5-10 nm) due to microphase separation of incompatible constitute blocks. The size and shape of the nanostructure can be customised by the molecular weight and volume fraction of the polymer blocks. However, the major challenge is BCPs do not phase separate into their signature ordered pattern above 100 nm, whereas for nanofeatures to be used as photonic gratings, they must be greater than 100 nm (typically ¼ wavelength). This is due to significant kinetic penalty arising from higher entanglement in high molecular weight polymers. In this work we present the results of exploiting commercially available block copolymers to phase separate into periodic domains greater than 100 nm. The process do not include any blending with homopolymers, or adding colloidal particles, and to our best knowledge, has not been yet achieved or reported in the literatures. We have pattern transferred the BCP mask to silicon substrate by reactive ion etch (ICP-RIE). The final product is black silicon, consists of hexagonally packed conic Si nanofeatures with diameter above 100nm and periodicity of 200 nm. The height of the Si nanopillars varies from 100 nm to 1 micron. We have characterized the angle dependent optical reflectance properties of the black silicon. The

  20. Morphological evolution of lamellar forming polystyrene-block-poly(4-vinylpyridine) copolymers under solvent annealing.

    Science.gov (United States)

    Ghoshal, Tandra; Chaudhari, Atul; Cummins, Cian; Shaw, Matthew T; Holmes, Justin D; Morris, Michael A

    2016-06-28

    In this work, we are reporting a very simple and efficient method to form lamellar structures of symmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymer thin films with vertically (to the surface plane) orientated lamellae using a solvent annealing approach. The methodology does not require any brush chemistry to engineer a neutral surface and it is the block neutral nature of the film-solvent vapour interface that defines the orientation of the lamellae. The microphase separated structure of two different molecular weight lamellar forming PS-block-P4VP copolymers formed under solvent vapour annealing was monitored using atomic force microscopy (AFM) so as to understand the morphological changes of the films upon different solvent exposure. In particular, the morphology changes from micellar structures to well-defined microphase separated arrangements. The choice of solvent/s (single and dual solvent exposure) and the solvent annealing conditions (temperature, time etc.) has important effects on structural transitions of the films and it was found that a block neutral solvent was required to realize vertically aligned P4VP lamellae. The results of the structural variation of the phase separated nanostructured films through the exposure to ethanol are also described. PMID:27240904

  1. Control of Protein Affinity of Bioactive Nanocellulose and Passivation Using Engineered Block and Random Copolymers.

    Science.gov (United States)

    Vuoriluoto, Maija; Orelma, Hannes; Zhu, Baolei; Johansson, Leena-Sisko; Rojas, Orlando J

    2016-03-01

    We passivated TEMPO-oxidized cellulose nanofibrils (TOCNF) toward human immunoglobulin G (hIgG) by modification with block and random copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA). The block copolymers reversibly adsorbed on TOCNF and were highly effective in preventing nonspecific interactions with hIgG, especially if short PDMAEMA blocks were used. In such cases, total protein rejection was achieved. This is in contrast to typical blocking agents, which performed poorly. When an anti-human IgG biointerface was installed onto the passivated TOCNF, remarkably high affinity antibody-antigen interactions were observed (0.90 ± 0.09 mg/m(2)). This is in contrast to the nonpassivated biointerface, which resulted in a significant false response. In addition, regeneration of the biointerface was possible by low pH aqueous wash. Protein A from Staphylococcus aureus was also utilized to successfully increase the sensitivity for human IgG recognition (1.28 ± 0.11 mg/m(2)). Overall, the developed system based on TOCNF modified with multifunctional polymers can be easily deployed as bioactive material with minimum fouling and excellent selectivity. PMID:26844956

  2. Sub-15nm Silicon Lines Fabrication via PS-b-PDMS Block Copolymer Lithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu;

    2013-01-01

    This paper describes the fabrication of nanodimensioned silicon structures on silicon wafers from thin films of a poly(styrene)-block-poly(dimethylsiloxane) (PS-b-PDMS) block copolymer (BCP) precursor self-assembling into cylindrical morphology in the bulk. The structure alignment of the PS-b-PDM...... subsequent plasma etching to the underlying substrate by an anisotropic dry etching process. SEM images reveal the formation of silicon nanostructures, notably of sub-15nm dimensions.......This paper describes the fabrication of nanodimensioned silicon structures on silicon wafers from thin films of a poly(styrene)-block-poly(dimethylsiloxane) (PS-b-PDMS) block copolymer (BCP) precursor self-assembling into cylindrical morphology in the bulk. The structure alignment of the PS......-b-PDMS (33 k–17 k) was conditioned by applying solvent and solvothermal annealing techniques. BCP nanopatterns formed after the annealing process have been confirmed by scanning electron microscope (SEM) after removal of upper PDMS wetting layer by plasma etching. Silicon nanostructures were obtained by...

  3. Effect of Increasing Molecular Weight on the A and B blocks of a Single-ion-conducting Block Copolymer Electrolyte for Lithium Batteries

    Science.gov (United States)

    Rojas, Adriana; Inceoglu, Sebnem; Thakker, Kanav; Mackay, Nikolaus; Balsara, Nitash

    Single-ion-conducting block copolymer electrolytes are desirable for lithium metal batteries due to their ability to eliminate salt concentration gradients across the electrolyte; i.e., the lithium ion transference number is approximately unity. A series of poly(ethylene oxide)- b-poly(styrenesulfonyllithium(trifluoromethylsulfonyl)imide) (PEO- b-PSLiTFSI) copolymers was studied wherein the molecular weights of both blocks were varied. Small angle x-ray scattering and ac impedance spectroscopy were used to probe the dependence of ionic conductivity on morphology. Preliminary work suggests that increasing the molecular weights of the blocks results in increased disorder and lower conductivity.

  4. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    International Nuclear Information System (INIS)

    In this article, we report the synthesis of magnetite nanoparticles (Fe3O4) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar n ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar n of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe3O4 and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively

  5. Self-assembly of block copolymers grafted onto a flat substrate: Recent progress in theory and simulations

    Science.gov (United States)

    Zheng, Wang; Bao-Hui, Li

    2016-01-01

    Block copolymers are a class of soft matter that self-assemble to form ordered morphologies on the scale of nanometers, making them ideal materials for various applications. These applications directly depend on the shape and size of the self-assembled morphologies, and hence, a high degree of control over the self-assembly is desired. Grafting block copolymer chains onto a substrate to form copolymer brushes is a versatile method to fabricate functional surfaces. Such surfaces demonstrate a response to their environment, i.e., they change their surface topography in response to different external conditions. Furthermore, such surfaces may possess nanoscale patterns, which are important for some applications; however, such patterns may not form with spun-cast films under the same condition. In this review, we summarize the recent progress of the self-assembly of block copolymers grafted onto a flat substrate. We mainly concentrate on the self-assembled morphologies of end-grafted AB diblock copolymers, junction point-grafted AB diblock copolymers (i.e., Y-shaped brushes), and end-grafted ABA triblock copolymers. Special emphasis is placed on theoretical and simulation progress. Project supported by the National Natural Science Foundation of China (Grant Nos. 20990234, 20925414, and 91227121), the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT1257), the Programme of Introducing Talents of Discipline to Universities, China, and by the Tianhe No. 1, China.

  6. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Mekkapat, Supachai; Thong-On, Bandit; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science (Thailand)

    2013-11-15

    In this article, we report the synthesis of magnetite nanoparticles (Fe{sub 3}O{sub 4}) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar {sub n} ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar {sub n} of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe{sub 3}O{sub 4} and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively.

  7. Orthogonal Synthesis of Block Copolymer via Photoinduced CuAAC and Ketene Chemistries.

    Science.gov (United States)

    Tasdelen, Mehmet Atilla; Taskin, Omer Suat; Celik, Cumali

    2016-03-01

    A novel route for the synthesis of poly(ethylene glycol)-b-polystyrene copolymer, starting from commercially available poly(ethylene glycol) methyl ether and azido terminated polystyrene prepared by atom transfer radical polymerization and subsequent nucleophilic substitution, is applied with simplicity and high efficiency. The combination of photoinduced copper (I)-catalyzed alkyne-azide cycloaddition (CuAAC) and ketene chemistry reactions proceeds either simultaneously or sequentially in a one-pot procedure under near-visible light irradiation. In both cases, excellent block copolymer formations are achieved, with an average molecular weight of around 7000 g mo1(-1) and a polydispersity index of 1.20. PMID:26847166

  8. Tetragonal Ordering in Block Copolymer-Homopolymer Blend Films Laterally Confined in a Square Well

    Science.gov (United States)

    Hur, Su-Mi; García-Cervera, Carlos; Kramer, Ed; Fredrickson, Glenn

    2009-03-01

    Self-consistent field theory (SCFT) simulations are presented for a melt blend of AB diblock copolymers and A homopolymers in a thin film confined to a square well. The work aims to guide self-assembly towards tetragonal ordering, which is a pattern of technological interest in block copolymer lithography. By using suitable A homopolymer additives, we have succeeded in achieving square lattices of cylinders not observed in the confined or bulk pure diblock system. A phase diagram is presented that shows the region of stability of the tetragonal phase as a function of chain length and volume fraction of the homopolymer additive, in addition to several other interesting phases that result from a competition between surface and bulk contributions to the free energy. Results are also presented on the effect of line edge roughness in the square confinement well on the achievement of robust and defect free tetragonal order.

  9. Periodic nanoscale patterning of polyelectrolytes over square centimeter areas using block copolymer templates.

    Science.gov (United States)

    Oded, Meirav; Kelly, Stephen T; Gilles, Mary K; Müller, Axel H E; Shenhar, Roy

    2016-05-18

    Nano-patterned materials are beneficial for applications such as solar cells, opto-electronics, and sensing owing to their periodic structure and high interfacial area. Here, we present a non-lithographic approach for assembling polyelectrolytes into periodic nanoscale patterns over cm(2)-scale areas. Chemically modified block copolymer thin films featuring alternating charged and neutral domains are used as patterned substrates for electrostatic self-assembly. In-depth characterization of the deposition process using spectroscopy and microscopy techniques, including the state-of-the-art scanning transmission X-ray microscopy (STXM), reveals both the selective deposition of the polyelectrolyte on the charged copolymer domains as well as gradual changes in the film topography that arise from further penetration of the solvent molecules and possibly also the polyelectrolyte into these domains. Our results demonstrate the feasibility of creating nano-patterned polyelectrolyte layers, which opens up new opportunities for structured functional coating fabrication. PMID:27104854

  10. Droplet synthesis of well-defined block copolymers using solvent-resistant microfluidic device.

    Science.gov (United States)

    Hoang, Phan Huy; Nguyen, Chi Thanh; Perumal, Jayakumar; Kim, Dong-Pyo

    2011-01-21

    Well-defined diblock copolymers were synthesized via an exothermic RAFT route by a droplet microfluidic process using a solvent-resistant and thermally stable fluoropolymer microreactor fabricated by a non-lithographic embedded template method. The resulting polymers were compared to products obtained from continuous flow capillary reactor and conventional bulk synthesis. The droplet based microreactor demonstrated superior molecular weight distribution control by synthesizing a higher molecular weight product with higher conversion and narrow polydispersity in a much shorter reaction time. The high quality of the as-synthesized block copolymer PMMA-b-PS led to a generation of micelles with a narrow size distribution that could be used as a template for well-ordered mesoporous silica with regular frameworks and high surface areas. PMID:21072416

  11. Synthesis of β-cyclodextrin-Based Star Block Copolymers with Thermo-Responsive Behavior

    Directory of Open Access Journals (Sweden)

    Agnes Wycisk

    2015-05-01

    Full Text Available Star polymers are one example of three-dimensional macromolecules containing several arms with similar molecular weight connected to a central core. Due to their compact structure and their enhanced segment density in comparison to linear polymers of the same molecular weight, they have attracted significant attention during recent years. The preparation of block-arm star copolymers with a permanently hydrophilic block and an “environmentally” sensitive block, which can change its nature from hydrophilic to hydrophobic, leads to nanometer-sized responsive materials with unique properties. These polymers are able to undergo a conformational change or phase transition as a reply to an external stimulus resulting in the formation of core–shell nanoparticles, which further tend to aggregate. Star-shaped copolymers with different cores were synthesized via atom transfer radical polymerization (ATRP. The core-first method chosen as synthetic strategy allows good control over the polymer architecture. First of all the multifunctional initiators were prepared by esterification reaction of the hydroxyl groups with 2-chloropropionyl chloride. Using β-cyclodextrin as core molecules, which possess a well-defined number of functional groups up to 21, allows defining the number of arms per star polymer. In order to prepare stimuli-responsive multi-arm copolymers, containing a stimuli-responsive (poly(N-isopropylacrylamide (PNIPAAm and a non-responsive block (poly(N,N-dimethylacrylamide (PDMAAm, consecutive ATRP was carried out. The polymers were characterized intensively using NMR spectroscopy and size exclusion chromatography (SEC, whereas the temperature-depending aggregation behavior in aqueous solution was determined via turbidimetry and differential scanning calorimetry (DSC.

  12. Structural changes in block copolymer micelles induced by cosolvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Elizabeth G.; Smart, Thomas P.; Jackson, Andrew J.; Sullivan, Millicent O.; Epps, III, Thomas H. (Delaware)

    2012-11-26

    We investigated the influence of tetrahydrofuran (THF) addition on the structure of poly(1,2-butadiene-b-ethylene oxide) [PB-PEO] micelles in aqueous solution. Our studies showed that while the micelles remained starlike, the micelle core-corona interfacial tension and micelle size decreased upon THF addition. The detailed effects of the reduction in interfacial tension were probed using contrast variations in small angle neutron scattering (SANS) experiments. At low THF contents (high interfacial tensions), the SANS data were fit to a micelle form factor that incorporated a radial density distribution of corona chains to account for the starlike micelle profile. However, at higher THF contents (low interfacial tensions), the presence of free chains in solution affected the scattering at high q and required the implementation of a linear combination of micelle and Gaussian coil form factors. These SANS data fits indicated that the reduction in interfacial tension led to broadening of the core-corona interface, which increased the PB chain solvent accessibility at intermediate THF solvent fractions. We also noted that the micelle cores swelled with increasing THF addition, suggesting that previous assumptions of the micelle core solvent content in cosolvent mixtures may not be accurate. Control over the size, corona thickness, and extent of solvent accessible PB in these micelles can be a powerful tool in the development of targeting delivery vehicles.

  13. Structural changes in block copolymer micelles induced by cosolvent mixtures

    International Nuclear Information System (INIS)

    We investigated the influence of tetrahydrofuran (THF) addition on the structure of poly(1,2-butadiene-b-ethylene oxide) [PB-PEO] micelles in aqueous solution. Our studies showed that while the micelles remained starlike, the micelle core-corona interfacial tension and micelle size decreased upon THF addition. The detailed effects of the reduction in interfacial tension were probed using contrast variations in small angle neutron scattering (SANS) experiments. At low THF contents (high interfacial tensions), the SANS data were fit to a micelle form factor that incorporated a radial density distribution of corona chains to account for the starlike micelle profile. However, at higher THF contents (low interfacial tensions), the presence of free chains in solution affected the scattering at high q and required the implementation of a linear combination of micelle and Gaussian coil form factors. These SANS data fits indicated that the reduction in interfacial tension led to broadening of the core-corona interface, which increased the PB chain solvent accessibility at intermediate THF solvent fractions. We also noted that the micelle cores swelled with increasing THF addition, suggesting that previous assumptions of the micelle core solvent content in cosolvent mixtures may not be accurate. Control over the size, corona thickness, and extent of solvent accessible PB in these micelles can be a powerful tool in the development of targeting delivery vehicles.

  14. Synthesis of PMMA-b-PU-b-PMMA tri-block copolymers through ARGET ATRP in the presence of air

    Directory of Open Access Journals (Sweden)

    P. Krol

    2013-03-01

    Full Text Available ARGET (activators regenerated by electron transfer ATRP (atom transfer radical polymerization has been successfully performed (in flasks fitted with rubber septa without the need for use of Schlenk line in the presence of limited amount of air and with a very small (370 ppm amount of copper catalyst together with an appropriate reducing agent Cu(0. Novelty of this work is that the poly(methyl methacrylate-block-polyurethane-block-poly(methyl methacrylate triblock copolymers were synthesized for the first time through ARGET ATRP, by using tertiary bromine-terminated polyurethane as a macroinitiator (MBP-PU-MBP, CuBr2 or CuCl2 as a catalyst and N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA or 2,2'-bipyridine (Bpy as a complexing agent. As the polymerization time increases, both the monomer conversion and ln([M]0/[M] increased and the molecular weight of copolymer increases linearly with increasing conversion. Theoretical number-average molecular weight (Mn, th of the tri-block copolymers was found to be comparable with number-average molecular weight determined by GPC analyses (Mn, GPC. These results indicate that the formation of the tri-block copolymers was through atom transfer radical polymerization mechanism. 1H and 13C NMR spectral methods were employed to confirm chemical structures of synthesized macroinitiator and tri-block copolymers. Mole percentage of PMMA in the tri-block copolymers was calculated using 1H NMR spectroscopy and was found to be comparable with the GPC results. Additionally, the studies of surface properties (confocal microscopy and SFE of tri-block copolymer coatings confirmed the presence of MMA segments.

  15. Directed Self-assembly of Block Copolymer with Sub-15 nm Domain Spacing Using Nanoimprinted Photoresist Templates

    Science.gov (United States)

    Sun, Zhiwei; Chen, Zhenbin; Zhang, Wenxu; Coughlin, E. Bryan; Xiao, Shuaigang; Russell, Thomas

    There has been increasing interest in preparing block copolymer thin films with ultra-small domain spacings for use as etching masks for ultra-high resolution nanolithography. One method to prepare block copolymer materials with small feature sizes is salt doping, increasing the Flory-Huggins interaction and allowing microphase separation to be maintained at lower molecular weights. Lamellae-forming P2VP- b-PS- b-P2VP block copolymer with various molecular weight was synthesized using RAFT polymerization with a dual functional chain transfer agent. Copper (II) Chloride or Gold (III) chloride was found to be selectively associated with P2VP block and increase the unfavorable interactions between PS and P2VP blocks, driving the disordered block copolymer into the ordered state. A 14 nm lamellar spacing of P2VP- b-PS- b-P2VP thin film was prepared using copper (II) Chloride doping after acetone vapor annealing on neutral brushes. Metallic nano-wire arrays were prepared after selective infiltration of platinum salt into the P2VP domain and oxygen plasma treatment. The directed self-assembly of salt doped P2VP- b-PS- b-P2VP triblock copolymer having long-rang lateral order on nanoimprinted photoresist templates with shallow trenches was also studied.

  16. Effect of Lithium Ion Concentration of a Single-Ion-Conducting Block Copolymer Electrolyte on the Morphology-Conductivity Relationship

    Science.gov (United States)

    Rojas, Adriana A.; Inceoglu, Sebnem; Mackay, Nikolaus G.; Devaux, Didier; Stone, Greg; Balsara, Nitash

    2015-03-01

    Single-ion-conducting electrolytes are desirable for lithium metal batteries because they enable the sole conduction of lithium ions, the reacting species in lithium batteries; hence, they avert detrimental battery limitations due to salt concentration gradients. A single-ion-conducting block copolymer electrolyte, poly(ethylene oxide)-b-polystyrenesulfonyllithium (trifluoromethyl sulfonyl) imide (PEO-b-PSLiTFSI), was characterized in-situ and ex-situ for its ionic conductivity and morphology using AC impedance spectroscopy and small angle x-ray scattering, respectively. This work is the first to elucidate the relationship between the two properties in a single-ion block copolymer electrolyte. The transference number for the copolymers was determined to be greater than or equal to 0.87, indicating that to a good approximation, the block copolymers are single-ion conducting electrolytes. It was found that increasing the molecular weight of the PSLiTFSI block led to an increase in the extent of block copolymer block-mixing and a change in the conductivity profile from discontinuous to continuous. These effects can be attributed to the disruption of PEO crystallization, which was shown to drive microphase separation. Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory.

  17. Spontaneous condensation in DNA-polystyrene- b-poly(l-lysine) polyelectrolyte block copolymer mixtures

    Science.gov (United States)

    Castelletto, V.; Hamley, I. W.; Kerstens, S. L. H.; Deacon, S.; Thomas, C. D.; Lübbert, A.; Klok, H.-A.

    2006-05-01

    We investigated the condensation of calf thymus DNA by amphiphilic polystyrenem-b-poly(l-lysine)n block copolymers ( PSm-b- PLysn, m, n = degree of polymerization), using small-angle X-ray scattering, polarized optical microscopy and laser scanning confocal microscopy. Microscopy studies showed that the DNA condenses in the form of fibrillar precipitates, with an irregular structure, due to electrostatic interactions between PLys and DNA. This is not modified by the presence of hydrophobic PS block. Scattering experiments show that the structure of the polyplexes corresponds to a local order of DNA rods which becomes more compact upon increasing n. It can be concluded that for DNA/ PSm-b- PLysn polyplexes, the balance between the PLys block length and the excess charge in the system plays an essential role in the formation of a liquid crystalline phase.

  18. Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu;

    2014-01-01

    antidot patterns after short solvo-thermal annealing. Unlike previous reports on this system, low temperature and short annealing time provide self-assembly in homogeneous thin films covering large substrate areas. This on-chip mask was then used for pattern transfer to the underlying silicon substrate......Block copolymers (BCP) are highly promising self-assembling precursors for scalable nanolithography. Very regular BCP nanopatterns can be used as on-chip etch masks. The first step in the processing of BCP thin films is usually the chemical modification of the substrate surface, typically by...... grafting of a brush layer that renders the surface energy neutral relative to the constituent blocks. We provide here a first study on rapid, low temperature self-assembly of PS-b-PDMS (polystyrene-block-polydimethylsiloxane) on silicon substrates without a brush layer. We show that it forms line and...

  19. Low Molecular Weight pDMAEMA-block-pHEMA Block-Copolymers Synthesized via RAFT-Polymerization: Potential Non-Viral Gene Delivery Agents?

    OpenAIRE

    Thomas Kissel; Christian Pfeiffer; Olga Samsonova; Markus Hellmund; Merkel, Olivia M.

    2011-01-01

    The aim of this study was to investigate non-viral pDNA carriers based on diblock-copolymers consisting of poly(2-(dimethyl amino)ethyl methacrylate) (pDMAEMA) and poly(2-hydroxyethyl methacrylate) (pHEMA). Specifically the block-lengths and molecular weights were varied to determine the minimal requirements for transfection. Such vectors should allow better transfection at acceptable toxicity levels and the entire diblock-copolymer should be suitable for renal clearance. For this purpose, a ...

  20. SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    A series of liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segment lengths were synthesized in tetrachloroethane by solution polycondensation in which hydroxyl terminated PC and acyl chloride terminated PHTH-6 were used. It is found that block copolymers with high molecular weight and welldefined structures were obtained. All the block copolymers exhibit a nematic liquid crystalline texture.

  1. Binding of amphiphilic and triphilic block copolymers to lipid model membranes: the role of perfluorinated moieties.

    Science.gov (United States)

    Schwieger, Christian; Achilles, Anja; Scholz, Sven; Rüger, Jan; Bacia, Kirsten; Saalwaechter, Kay; Kressler, Jörg; Blume, Alfred

    2014-09-01

    A novel class of symmetric amphi- and triphilic (hydrophilic, lipophilic, fluorophilic) block copolymers has been investigated with respect to their interactions with lipid membranes. The amphiphilic triblock copolymer has the structure PGMA(20)-PPO(34)-PGMA(20) (GP) and it becomes triphilic after attaching perfluoroalkyl moieties (F9) to either end which leads to F(9)-PGMA(20)-PPO(34)-PGMA(20)-F(9) (F-GP). The hydrophobic poly(propylene oxide) (PPO) block is sufficiently long to span a lipid bilayer. The poly(glycerol monomethacrylate) (PGMA) blocks have a high propensity for hydrogen bonding. The hydrophobic and lipophobic perfluoroalkyl moieties have the tendency to phase segregate in aqueous as well as in hydrocarbon environments. We performed differential scanning calorimetry (DSC) measurements on polymer bound lipid vesicles under systematic variation of the bilayer thickness, the nature of the lipid headgroup, and the polymer concentration. The vesicles were composed of phosphatidylcholines (DMPC, DPPC, DAPC, DSPC) or phosphatidylethanolamines (DMPE, DPPE, POPE). We showed that GP as well as F-GP binding have membrane stabilizing and destabilizing components. PPO and F9 blocks insert into the hydrophobic part of the membrane concomitantly with PGMA block adsorption to the lipid headgroup layer. The F9 chains act as additional membrane anchors. The insertion of the PPO blocks of both GP and F-GP could be proven by 2D-NOESY NMR spectroscopy. By fluorescence microscopy we show that F-GP binding increases the porosity of POPC giant unilamellar vesicles (GUVs), allowing the influx of water soluble dyes as well as the translocation of the complete triphilic polymer and its accumulation at the GUV surface. These results open a new route for the rational design of membrane systems with specific properties. PMID:24942348

  2. The morphology of block copolymer micelles in supercritical carbon dioxide by small-angle neutron and X-ray scattering

    International Nuclear Information System (INIS)

    Above its critical point, carbon dioxide forms a supercritical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insol- uble in CO2, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO2-phobic PS core and a CO2-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell and Lodge [Adv. Polym. Sci. (1992), 100, 31-46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids. (orig.)

  3. The morphology of block copolymer micelles in supercritical carbon dioxide by small-angle neutron and X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Londono, J.D.; Dharmapurikar, R.; Cochran, H.D.; Wignall, G.D. [Oak Ridge National Lab., TN (United States); McClain, J.B.; Betts, D.E.; Canelas, D.A.; DeSimone, J.M.; Samulski, E.T.; Chillura-Martino, D.; Triolo, R.

    1997-10-01

    Above its critical point, carbon dioxide forms a supercritical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insol- uble in CO{sub 2}, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO{sub 2}-phobic PS core and a CO{sub 2}-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell and Lodge [Adv. Polym. Sci. (1992), 100, 31-46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids. (orig.). 24 refs.

  4. High quality sub-10 nm graphene nanoribbons by on-chip PS-b-PDMS block copolymer lithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Caridad, Jose; Schulte, Lars;

    2015-01-01

    Block copolymer self-assembly holds great promise as a rapid, cheap and scalable approach to nanolithography. We present a straightforward method for fabrication of sub-10 nm line patterns from a lamellar polystyrene-b-polydimethylsiloxane (SD) block copolymer with total average molecular weight of...... block and the graphene under PS. Raman analysis supports the formation of graphene nanoribbons with an average distance between defects corresponding to the oxidized PDMS pitch, with no sign of defects generated in the ribbon channel. This suggests a high degree of protection of the nanoribbons by the...

  5. Morphology and Dynamic Mechanical Properties of Styrene Containing Tri-Block Copolymers for Electromagnetic Wave Interaction Applications

    Science.gov (United States)

    Peddini, S.; Mauritz, K.; Nikles, D.; Weston, J.

    2008-03-01

    Styrene containing triblock copolymers, namely poly(styrene-ethylene/butylene-styrene) (SEBS) and poly(styrene-butadiene-styrene)] (SBS), were selectively modified by attaching polar groups to facilitate the in-growth of an inorganic component. In case of SEBS, the styrene block was sulfonated, and in SBS, the butadiene block was hydroxylated. The extent of modification was determined by analytical and spectroscopic methods. This presentation shows the morphology and dynamical mechanical properties of both block copolymers before and after modification. Nanocomposites of these block copolymers were prepared by inclusion of magnetic metal oxides via an in-situ precipitation and self assembly processes and their morphology and dynamical mechanical properties were studied. Magnetic properties of these polymers filled with iron oxide nanoparticles were measured using an alternating gradient magnetometer (AGM) at room temperature to observe the magnetic hysteresis.

  6. Simultaneous Photoinduced ATRP and CuAAC Reactions for the Synthesis of Block Copolymers.

    Science.gov (United States)

    Murtezi, Eljesa; Yagci, Yusuf

    2014-09-01

    Atom transfer radical polymerization (ATRP) and copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, both utilizing copper(I) (Cu(I)) complexes, make a tremendous progress in synthetic polymer chemistry. Independently or in combination with other polymerization processes, they give access to the synthesis of polymers with well-defined structures, desired molecular architectures, and a wide variety of functionalities. Here, a novel in situ photoinduced formation of block copolymers is described by simultaneous ATRP and CuAAC processes. This approach relies on the direct reduction of initially charged copper(II) complexes to Cu(I) complexes to trigger both ATRP and CuAAC reactions coinciding under UV light at ambient temperature in one pot. Its synthetic utility is demonstrated on a model block copolymerization process by photoinduced ATRP of methyl methacrylate (MMA) using an initiator possessing acetylene functionality and concomitant click reaction between thus formed α-acetylene-poly(methyl methacrylate) (Ac-PMMA) and independently prepared azide functional polystyrene (PS-N3 ). Successful formation of PS-b-PMMA block copolymer is confirmed by FT-IR and (1) H NMR spectral analysis and gel permeation chromatography (GPC) measurements. PMID:25200624

  7. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K. (UW)

    2013-09-26

    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.

  8. Magnetic properties of barium ferrite dispersed within polystyrene-butadiene-styrene block copolymers.

    Science.gov (United States)

    Chipara, M; Skomski, R; Ali, N; Hui, D; Sellmyer, D J

    2009-06-01

    Magnetic properties of nanocomposite materials obtained by dispersing barium ferrite nanoparticles within polystyrene-butadiene-styrene block copolymer, in the temperature range, 300 to 500 K are reported. The temperature dependence of the magnetization at saturation, averaged uniaxial magnetocrystalline anisotropy, and coercive field of thick films are analyzed. A "matrix effect" was noticed within the glass transition range of the hard component (polystyrene) of the polymeric matrix. The reported modifications of the magnetic properties were assigned to the competition between the magnetic and mechanical reorientation of nanoparticles within the polymeric matrix. Such modifications were not observed in barium ferrite dispersed in cement. PMID:19504902

  9. Self-assembled isoporous block copolymer membranes with tuned pore sizes

    KAUST Repository

    Yu, Haizhou

    2014-07-23

    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Role of Synthetic and Dimensional Synthetic Organic Chemistry in Block Copolymer Micelle Nanosensor Engineering

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar

    This thesis investigated the role of amphiphilic triblock copolymer micelle nanomaterials in nanosensors, with emphasis on the synthesis of micelle particle sensors. The thesis is focused on the role of synthetic and dimensional synthetic organic chemistry in amphiphilic triblock core...... micelles. Shell cross-linking on PEG-b-PAEMA-b-PS micelles was performed by amidation reactions between the amino groups of PAEMA blocks using a di-carboxylic acid cross-linker. Also a dendritic cross-linker based click chemistry was used to stabilize the PEG-b-PAEMA-b-PES micelle having click readied PES...

  11. Block copolymer directed synthesis of mesoporous TiO2 for dye-sensitized solar cells

    OpenAIRE

    Nedelcu, M.; Lee, J.; Crossland, E. J. W.; Warren, S.C.; Orilall, M. C.; Guldin, S.; Huettner, S.; Ducati, C.; Eder, D.; Wiesner, U.; Steiner, U.; Snaith, H. J.

    2009-01-01

    The morphology of TiO2 plays an important role in the operation of solid-state dye-sensitized solar cells. By using polyisoprene-block-ethyleneoxide (PI-b-PEO) copolymers as structure directing agents for a sol-gel based synthesis of mesoporous TiO2, we demonstrate a strategy for the detailed control of the semiconductor morphology on the 10 nm length scale. The careful adjustment of polymer molecular weight and titania precursor content is used to systematically vary the material structure a...

  12. Tunable Mesoporous Bragg Reflectors Based on Block-Copolymer Self-Assembly

    KAUST Repository

    Guldin, Stefan

    2011-07-06

    Mesoporous Bragg reflectors are a promising materials platform for photovoltaics, light emission, and sensing. A fast and versatile fabrication route that relies on the self-assembly of the block copolymer poly(isoprene-b-ethylene oxide) in combination with simple sol-gel chemistry is reported. The method allows extended control over porosity and pore size in the resulting inorganic material and results in high-quality optical elements. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Thermally Induced Structural Evolution and Performance of Mesoporous Block Copolymer-Directed Alumina Perovskite Solar Cells

    OpenAIRE

    Tan, Kwan Wee; Moore, David T.; Saliba, Michael; Sai, Hiroaki; Estroff, Lara A.; Hanrath, Tobias; Snaith, Henry J.; Wiesner, Ulrich

    2014-01-01

    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI3–x Cl x ) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI3–x Cl x material evolution to be ...

  14. Single-Crystal Diffraction from Two-Dimensional Block Copolymer Arrays

    International Nuclear Information System (INIS)

    The structure of oriented 2D block copolymer single crystals is characterized by grazing-incidence small-angle x-ray diffraction, demonstrating long-range sixfold orientational order. From line shape analysis of the higher-order Bragg diffraction peaks, we determine that translational order decays algebraically with a decay exponent η=0.2, consistent with the Kosterlitz-Thouless-Halperin-Nelson-Young theory for a 2D crystal with a shear modulus μ=2x10-4 N/m

  15. Improved cost-effectiveness of the block co-polymer anneal process for DSA

    Science.gov (United States)

    Pathangi, Hari; Stokhof, Maarten; Knaepen, Werner; Vaid, Varun; Mallik, Arindam; Chan, Boon Teik; Vandenbroeck, Nadia; Maes, Jan Willem; Gronheid, Roel

    2016-04-01

    This manuscript first presents a cost model to compare the cost of ownership of DSA and SAQP for a typical front end of line (FEoL) line patterning exercise. Then, we proceed to a feasibility study of using a vertical furnace to batch anneal the block co-polymer for DSA applications. We show that the defect performance of such a batch anneal process is comparable to the process of record anneal methods. This helps in increasing the cost benefit for DSA compared to the conventional multiple patterning approaches.

  16. Preparation of mesoporous cerium oxide templated by tri-block copolymer for solid oxide fuel cell

    International Nuclear Information System (INIS)

    Mesoporous structured CeO2 with high specific surface area was synthesized at ambient temperature in this study. The synthesis of this material was accomplished using a tri-block copolymer as the organic supermolecular template and the cerium nitrate hexahydrate as the inorganic precursor. X-ray diffraction, nitrogen adsorption and desorption isotherms and transmission electron microscopy have been used to characterize the mesoporous structure. The nitrogen adsorption and desorption isotherms analysis indicates that the average pore size is 3.5 and 3.4 nm and the specific surface area is 155 and 103 m2/g for the samples calcined at 523 and 723 K, respectively

  17. Direct Measurement of Interfacial Curvature Distributions in a Bicontinuous Block Copolymer Morphology

    International Nuclear Information System (INIS)

    Self-consistent field theory predicts that the complex phase behavior of block copolymers does not originate solely from the interface seeking constant mean curvature as once thought, but instead reflects competing minimization of interfacial tension and packing frustration. To test this prediction, we directly measure interfacial curvature distributions from a 3D image reconstruction of the bicontinuous gyroid morphology. Results obtained here reveal that the gyroid interface is not constant mean curvature and confirm the importance of packing frustration in the stabilization of such complex nanostructures. (c) 2000 The American Physical Society

  18. The interactions between microphase separation and crystallization in block copolymers containing polyethylene

    Science.gov (United States)

    Quiram, Daniel Jonathan

    The interactions between microphase separation and crystallization were examined in block copolymers containing polyethylene of varying chemistry, composition (fsb{E} = 0.26-0.88, where fsb{E} is weight fraction polyethylene), and molecular weight. Block copolymer compositions were altered to explore crystallization from three distinct melt morphologies: body-centered cubic spheres, hexagonally-packed cylinders, and alternating lamellae. Polymer morphology was investigated on a size-scale ranging from angstroms to microns, employing wide-angle and small-angle x-ray scattering (WAXS and SAXS), small-angle light scattering, and differential scanning calorimetry. The primary series of diblock copolymers investigated were polyethylene-b-poly(3-methyl-1-butene) (E/MB, where MB is an olefinic rubber; fsb{E} = 0.26-0.27). This composition led to a cylindrical morphology when the melt microphase separated. Molecular weights were varied to obtain differing degrees of melt incompatibility, ranging from disordered to strongly segregated. Crystallization from strongly segregated melts was confined to the cylindrical microdomains, essentially independent of thermal history. In contrast, the morphology produced by crystallization from weakly segregated melts was highly dependent upon thermal history. Several block copolymers with microphase-separated melts containing an E block and either polystyrene (glass transition temperature, Tsb{g}≈ 100sp°C) or poly(vinylcyclohexane) (Tsb{g}≈ 135sp°C) were investigated to determine the effect of a vitreous component on crystallization. SAXS experiments showed that vitrification of the amorphous material effectively confined E crystallization to its melt domain phase: cylinders in a glassy matrix, lamellae, and matrices surrounding both glassy cylinders and spheres. Crystalline chain orientation within cylinders was examined through WAXS. The chains aligned preferentially and this orientation varied depending on chain diffusion during

  19. Poly(lactide): from hyperbranched copolyesters to new block copolymers with functional methacrylates

    OpenAIRE

    Wolf, Florian Karsten

    2010-01-01

    The prologue of this thesis (Chapter 1.0) gives a general overview on lactone based poly(ester) chemistry with a focus on advanced synthetic strategies for ring-opening polymerization, including the emerging field of organo catalysis. This section is followed by a presentation of the state-of the art regarding the two central fields of the thesis: (i) polyfunctional and branched poly(ester)s in Chapter 1.1 as well as (ii) the development of new poly(ester) based block copolymers with function...

  20. A new supramolecular route for using Rod-Coil block copolymers in photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sary, Nicolas [Department of Physics and FRIMAT Center for Nanomaterials, University of Fribourg (Switzerland); Richard, Fanny; Brochon, Cyril; Leclerc, Nicolas; Hadziioannou, Georges [Laboratoire d' Ingenierie des Polymeres pour les Hautes Technologies Universite de Strasbourg, Ecole Europeenne de Chimie Polymeres et Materiaux (France); Leveque, Patrick; Heiser, Thomas [Institut d' Electronique du Solide et des Systemes Centre National de la Recherche Scientifique, Universite de Strasbourg (France); Audinot, Jean-Nicolas [Science and Analysis of Materials Department Public Research Centre Gabriel Lippmann, Belvaux (Luxembourg); Berson, Solenn [Laboratoire des Composants Solaires, Institut de l' Energie Solaire Commissariat a l' energie atomique, Le Bourget Du Lac (France); Mezzenga, Raffaele [Department of Physics and FRIMAT Center for Nanomaterials, University of Fribourg (Switzerland); Nestle Research Center, Lausanne (Switzerland)

    2010-02-09

    A new polymer blend formed by poly(3-hexylthiophene)-poly(4-vinylpyridine) (P3HT- P4VP) block copolymers and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. The P4VP and PCBM are mixed together by weak supramolecular interactions, and the resulting materials exhibit microphase separated morphologies of electron-donor and electron-acceptor rich domains. The properties of the blend, used in photovoltaic devices as active layers, are also discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  1. Cathepsin S-cleavable, multi-block HPMA copolymers for improved SPECT/CT imaging of pancreatic cancer.

    Science.gov (United States)

    Fan, Wei; Shi, Wen; Zhang, Wenting; Jia, Yinnong; Zhou, Zhengyuan; Brusnahan, Susan K; Garrison, Jered C

    2016-10-01

    This work continues our efforts to improve the diagnostic and radiotherapeutic effectiveness of nanomedicine platforms by developing approaches to reduce the non-target accumulation of these agents. Herein, we developed multi-block HPMA copolymers with backbones that are susceptible to cleavage by cathepsin S, a protease that is abundantly expressed in tissues of the mononuclear phagocyte system (MPS). Specifically, a bis-thiol terminated HPMA telechelic copolymer containing 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Three maleimide modified linkers with different sequences, including cathepsin S degradable oligopeptide, scramble oligopeptide and oligo ethylene glycol, were subsequently synthesized and used for the extension of the HPMA copolymers by thiol-maleimide click chemistry. All multi-block HPMA copolymers could be labeled by (177)Lu with high labeling efficiency and exhibited high serum stability. In vitro cleavage studies demonstrated highly selective and efficient cathepsin S mediated cleavage of the cathepsin S-susceptible multi-block HPMA copolymer. A modified multi-block HPMA copolymer series capable of Förster Resonance Energy Transfer (FRET) was utilized to investigate the rate of cleavage of the multi-block HPMA copolymers in monocyte-derived macrophages. Confocal imaging and flow cytometry studies revealed substantially higher rates of cleavage for the multi-block HPMA copolymers containing the cathepsin S-susceptible linker. The efficacy of the cathepsin S-cleavable multi-block HPMA copolymer was further examined using an in vivo model of pancreatic ductal adenocarcinoma. Based on the biodistribution and SPECT/CT studies, the copolymer extended with the cathepsin S susceptible linker exhibited significantly faster clearance and lower non-target retention without compromising tumor targeting. Overall, these results indicate that

  2. Manipulating the morphologies of poly(vinyl alcohol) block copolymer surfactants

    Science.gov (United States)

    Repollet-Pedrosa, Milton H.

    Amphiphilic block copolymers (ABCs) are macromolecules containing well-defined hydrophilic and hydrophobic segments that self-assemble into nanoscale aggregates such as spherical and cylindrical micelles and vesicles, when dispersed in block-selective solvents. ABCs possess a miniscule critical micelle concentration, which results in kinetically trapped and persistent assemblies in solution with slow chain exchange between aggregates. This makes them useful as rheological modifiers for personal care products, enhanced oil recovery, and drug delivery formulations. Their utility in many of these applications is crucially dependent on the ability to control the micellar morphologies that they adopt in selective solvents. Triggering ABC micellar morphological transformations, i.e. from spherical to cylindrical micelles, is important for generating "on-demand" stimuli-responsive morphologies that control the aggregate morphology and the bulk solution properties in any given application. In this thesis, we develop the straightforward synthesis of biodegradable and biocompatible ABCs comprised of poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA), with narrow molecular distributions and variable yet well-defined compositions. These block copolymer amphiphiles readily form spherical micelles in aqueous dispersions. We demonstrate that the addition of a water-soluble poly(ethylene oxide) (PEO) homopolymer to these dispersions results in a rapid transformation of these spherical micelles into cylindrical micelles. Dilution of these cylindrical micelles with water induces their reversion to spherical micelles. Our results indicate that the reversible morphology change depends sensitively on the PEO homopolymer concentration and molecular weight, as well as the length of the PVA corona block of the micelles. Through a series of quantitative 1H NMR studies, we found that the preferential partitioning of PEO homopolymer into the PVAc micellar core drives this morphological

  3. Comparison of proton conducting polymer electrolyte membranes prepared from multi-block and random copolymers based on poly(arylene ether ketone)

    Science.gov (United States)

    Kang, Kyuhyun; Kim, Dukjoon

    2015-05-01

    Multi-block and random copolymers based on poly(arylene ether ketone) with the similar IEC values are synthesized. The chemical structure of the hydrophobic and hydrophilic oligomers and the copolymers synthesized from them is identified using 1H - and 19F- nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflection fourier transform infrared (ATR-FTIR) spectroscopy, and gel permeation chromatography (GPC). The development of distinguished hydrophobic-hydrophilic phase separation is confirmed by small-angle X-ray scattering (SAXS) spectroscopy. The proton conductivity and water uptake along with the thermal, mechanical, oxidative stabilities are measured to investigate the effect of the copolymer structure on the membrane properties. While water uptake is similar with respect to each other, the proton conductivity of the multi-block copolymer membrane is higher than that of random one at the same levels of IEC. It results from much more distinct hydrophobic-hydrophilic phase separation formed in the multi-block copolymer membrane than the random one. The ion cluster dimension of the multi-block copolymer membranes is larger than that of the random copolymer membranes from the SAXS analysis. Also, the ion cluster dimension distribution of the block copolymer membranes is much narrower than that of random ones. The multi-block copolymer membranes illustrate superior oxidation stability to the random copolymer membrane due to the same phase separation difference.

  4. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    Science.gov (United States)

    Valenti, G.; La Carta, S.; Mazzotti, G.; Rapisarda, M.; Perna, S.; Di Gesù, R.; Giorgini, L.; Carbone, D.; Recca, G.; Rizzarelli, P.

    2016-05-01

    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient's compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye's diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10-60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy (1H-NMR, 13C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of different kinetic

  5. Thermally sensitive block copolymer particles prepared via aerosol flow reactor method: Morphological characterization and behavior in water

    OpenAIRE

    Nykänen, Antti; Rahikkala, Antti; Hirvonen, Sami-Pekka; Aseyev, Vladimir; Tenhu, Heikki; Mezzenga, Raffaele; Raula, Janne; Kauppinen, Esko; Ruokolainen, Janne

    2012-01-01

    This work describes properties of thermo-sensitive submicron sized particles having the same chemical composition but different morphologies. These particles have been prepared with an aerosol technique using dimethylformamide solutions of linear polystyrene-block-poly(N-isopropylacrylamide-block-polystyrene, PS-b-PNIPAM-b-PS. The particles were characterized by cryo-electron microscopy, microcalorimetry, and light scattering. Block-copolymers self-assembled within the particles forming onion...

  6. Morphology-controlled growth of perylene derivative induced by double-hydrophilic block copolymers

    Directory of Open Access Journals (Sweden)

    Minghua Huang

    2016-01-01

    Full Text Available Controlled growth of technically relevant perylene derivative 3, 4, 9, 10-perylenetetracarboxylic acid potassium salt (PTCAPS, with tuneable morpologies, has been successfully realized by a recrystallization method using a double-hydrophilic block copolymer poly (ethylene glycol-block poly (ethyleneimine (PEG-b-PEI as the structure directing agent. The {001} faces of PTCAPS are most polar and adsorb the oppositively charged polymer additive PEG-b-PEI well by electrostatic attraction. By simply adjusting the PEG-b-PEI concentration, systematic morphogenesis of PTCAPS from plates to microparticles composed of various plates splaying outwards could be realized. Furthermore, the variation of pH value of the recrystallization solution could induce the change of the interaction strength between PEG-b-PEI additive and PTCAPS and thus modify the morphology of PTCAPS from microparticles composed of various plates to ultralong microbelts.

  7. Mechanically and structurally robust sulfonated block copolymer membranes for water purification applications

    International Nuclear Information System (INIS)

    The effective removal of ionic pollutants from contaminated water using negatively charged nanofiltration membranes is demonstrated. Block copolymers comprising polystyrene (PS) and partially hydrogenated polyisoprene (hPI) were synthesized by varying chain architectures. A one step procedure of cross-linking (hPI blocks) and sulfonation reactions (PS chains) was then carried out, which was revealed as an effective method to enhance mechanical integrity of membranes while hydrophilic sulfonated chains remain intact. In particular, the control of chain architecture allows us to create a synergetic effect on optimizing charge densities of the membrane, water permeability, and mechanical integrity under water purification conditions. The best performing membrane can almost completely (>99%) reject various divalent cations and also show NO3− rejection > 85% and Na+ rejection > 87%. Well defined nanostructures (tens of nanometers) as well as the periodically arranged water domains (a few nanometers) within hydrophilic phases of the hydrated membranes were confirmed by in situ neutron scattering experiments. (paper)

  8. Hierarchical multiscale hyperporous block copolymer membranes via tunable dual-phase separation.

    Science.gov (United States)

    Yoo, Seungmin; Kim, Jung-Hwan; Shin, Myoungsoo; Park, Hyungmin; Kim, Jeong-Hoon; Lee, Sang-Young; Park, Soojin

    2015-07-01

    The rational design and realization of revolutionary porous structures have been long-standing challenges in membrane science. We demonstrate a new class of amphiphilic polystyrene-block-poly(4-vinylpyridine) block copolymer (BCP)-based porous membranes featuring hierarchical multiscale hyperporous structures. The introduction of surface energy-modifying agents and the control of major phase separation parameters (such as nonsolvent polarity and solvent drying time) enable tunable dual-phase separation of BCPs, eventually leading to macro/nanoscale porous structures and chemical functionalities far beyond those accessible with conventional approaches. Application of this BCP membrane to a lithium-ion battery separator affords exceptional improvement in electrochemical performance. The dual-phase separation-driven macro/nanopore construction strategy, owing to its simplicity and tunability, is expected to be readily applicable to a rich variety of membrane fields including molecular separation, water purification, and energy-related devices. PMID:26601212

  9. Data on macrophage mediated muscle transfection upon delivery of naked plasmid DNA with block copolymers

    Directory of Open Access Journals (Sweden)

    Vivek Mahajan

    2016-06-01

    Full Text Available The data contains 14 figures supporting the research article “Horizontal gene transfer from macrophages to ischemic muscles upon delivery of naked DNA with Pluronic block copolymers” [1]. The data explains the surgical procedure and histological characterization of Murine Hind Limb Ischemia. The data also shows the kinetics of luciferase gene expression, spread of GFP expression through muscle and the colocalization of GFP with cellular markers in ischemic muscles injected with pDNA alone or pDNA/Pluronic. Finally the data shows the effect of Pluronic Block Copolymer to enhance total gene expression (cmv-promoter driven luciferase gene in coculture of DNA transfected MØs with muscle cells.

  10. Morphology-controlled growth of perylene derivative induced by double-hydrophilic block copolymers

    Science.gov (United States)

    Huang, Minghua; Antonietti, Markus; Cölfen, Helmut

    2016-01-01

    Controlled growth of technically relevant perylene derivative 3, 4, 9, 10-perylenetetracarboxylic acid potassium salt (PTCAPS), with tuneable morpologies, has been successfully realized by a recrystallization method using a double-hydrophilic block copolymer poly (ethylene glycol)-block poly (ethyleneimine) (PEG-b-PEI) as the structure directing agent. The {001} faces of PTCAPS are most polar and adsorb the oppositively charged polymer additive PEG-b-PEI well by electrostatic attraction. By simply adjusting the PEG-b-PEI concentration, systematic morphogenesis of PTCAPS from plates to microparticles composed of various plates splaying outwards could be realized. Furthermore, the variation of pH value of the recrystallization solution could induce the change of the interaction strength between PEG-b-PEI additive and PTCAPS and thus modify the morphology of PTCAPS from microparticles composed of various plates to ultralong microbelts.

  11. Preparation of Polyion Complex Micelles Using Block Copolymers for SiRNA Delivery.

    Science.gov (United States)

    Kim, Hyun Jin; Zheng, Meng; Miyata, Kanjiro; Kataoka, Kazunori

    2016-01-01

    Polyion complex (PIC) micelles can be prepared through the spontaneous assembly of cationic block copolymers with oppositely charged short interfering RNAs (SiRNAs). Their core-shell architectures offer a delivery platform for vulnerable SiRNA, improving their biological activities for medicinal applications such as tumor-targeted therapy. Here, we report a protocol for the preparation of SiRNA-loaded PIC micelles using a poly(ethylene glycol)-block-poly(aspartamide) derivative, providing the physicochemical criteria for well-defined micellar formulation. In addition, we describe protocols for a stability assay for SiRNA-loaded PIC micelles in the presence of serum using fluorescence correlation spectroscopy and a luciferase assay for cultured cancer cells stably expressing luciferase, thus providing the biological criteria for further medicinal applications. PMID:26472445

  12. Negative-tone block copolymer lithography by in situ surface chemical modification.

    Science.gov (United States)

    Kim, Bong Hoon; Byeon, Kyeong-Jae; Kim, Ju Young; Kim, Jinseung; Jin, Hyeong Min; Cho, Joong-Yeon; Jeong, Seong-Jun; Shin, Jonghwa; Lee, Heon; Kim, Sang Ouk

    2014-10-29

    Negative-tone block copolymer (BCP) lithography based on in situ surface chemical modification is introduced as a highly efficient, versatile self-assembled nanopatterning. BCP blends films consisting of end-functionalized low molecular weight poly(styrene-ran-methyl methacrylate) and polystyrene-block-Poly(methyl methacylate) can produce surface vertical BCP nanodomains on various substrates without prior surface chemical treatment. Simple oxygen plasma treatment is employed to activate surface functional group formation at various substrates, where the end-functionalized polymers can be covalently bonded during the thermal annealing of BCP thin films. The covalently bonded brush layer mediates neutral interfacial condition for vertical BCP nanodomain alignment. This straightforward approach for high aspect ratio, vertical self-assembled nanodomain formation facilitates single step, site-specific BCP nanopatterning widely useful for various substrates. Moreover, this approach is compatible with directed self-assembly approaches to produce device oriented laterally ordered nanopatterns. PMID:24912807

  13. Effect of hydrostatic pressure on phase behavior of deutrated polystyrene-block-poly(n-alkyl methacrylate) copolymer

    International Nuclear Information System (INIS)

    The effect of hydrostatic pressure on phase behavior of deutrated polystyrene-block-poly(n-alkyl methacrylate) [dPS-PnAMA] copolymers with various alkyl chains was investigated by small angle neutron scattering (SANS). Polystyrene-block-poly(n-alkyl methacrylate) copolymers are strongly dependant on both pressure and alkyl number (n) even though these block copolymers have just weak interaction. dPS-PnAMA with n = 2 ∼ 4 exhibited only Lower Disordered-to-Order Transit ion (LDOT), whereas the Ordered-to-Disorder (ODT) was found for n = 1 and n = 6. Additionally, a closed-loop phase behavior was found for n = 5. The order-to-disorder transition (ODT) is only weakly dependent on pressure, whereas, the Lower Disorder-to-Order Transition (LDOT) is strongly dependent on pressure. However, phase transition for a closed-loop phase behavior showed the largest pressure dependence

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

    Science.gov (United States)

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

    2014-07-22

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

  15. Synthesis of Dextran/Methoxy Poly(ethylene glycol Block Copolymer

    Directory of Open Access Journals (Sweden)

    Young-Il Jeong

    2013-01-01

    Full Text Available We synthesized a block copolymer composed of dextran and methoxy poly(ethylene glycol (mPEG. To accomplish this, the end group of dextran was modified by reductive amination. The aminated dextran (Dextran-NH2 showed the intrinsic peaks of both dextran at 3~5.5 ppm and hexamethylene diamine at 1~2.6 ppm at 1H nuclear magnetic resonance (NMR spectrum. The amino end group of dextran was conjugated with mPEG to make the block copolymer consisting of dextran/mPEG (abbreviated as DexPEG. The synthesized aminated dextran and DexPEG were characterized using 1H NMR and gel permeation chromatography (GPC. The molecular weight and conjugation yield were estimated by comparing the intensity ratio of the proton peaks of the glucose molecule (4.9 ppm and 3.3~4.0 ppm to that of the ethylene group of mPEG (3.7 ppm. Abundant hydroxyl group in the dextran chain can be used as a source of bioactive agent conjugation.

  16. Memory effects in annealed hybrid gold nanoparticles/block copolymer bilayers

    Directory of Open Access Journals (Sweden)

    Ruffino Francesco

    2011-01-01

    Full Text Available Abstract We report on the use of the self-organization process of sputtered gold nanoparticles on a self-assembled block copolymer film deposited by horizontal precipitation Langmuir-Blodgett (HP-LB method. The morphology and the phase-separation of a film of poly-n-butylacrylate-block-polyacrylic acid (PnBuA-b-PAA were studied at the nanometric scale by using atomic force microscopy (AFM and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS. The templating capability of the PnBuA-b-PAA phase-separated film was studied by sputtering gold nanoparticles (NPs, forming a film of nanometric thickness. The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg. The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition. The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

  17. Synergistic templated self-assembly of cellulose nanocrystals in thin block copolymer films

    Science.gov (United States)

    Grolman, Danielle; Gilman, Jeffrey; Davis, Chelsea; Karim, Alamgir

    2015-03-01

    Nanofillers in thin polymer films offer unique advantage to potentially modify the film's thermal, optical, electrical and mechanical properties due to the high surface area to volume ratio and intrinsic property change at the nanoscale. Nanofilled polymer films have been shown to exhibit unusual film stability to dewetting with a nonmonotonic behavior with nanofiller loading, potentially arising from factors such as competitive phase behavior and filler aggregation, particularly in the high nanofiller concentration limit. In this regard, block copolymer films can act as ideal nanoscale structured templates to selectively sequester and organize nanofillers. In conjunction with incorporated cellulose nanocrystals (CNCs), we seek to understand how individual anisotropic nanofillers can provide synergistic reinforcement to inherently anisotropic nanostructured block copolymer films. A clear enhancement in the Young's Modulus was observed with increased CNC loading using strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) for thin films. To this end, we examine the nanoscale to microscale morphology of the blend film through AFM, TEM and grazing incidence small-angle x-ray scattering (GISAXS), and CNC dispersion and percolation through high-intensity grazing incidence wide-angle x-ray scattering (GIWAXS) analysis.

  18. High Aspect Ratio Sub-15 nm Silicon Trenches From Block Copolymer Templates

    Science.gov (United States)

    Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Olynick, Deirdre; Russell, Thomas; University of Massachusetts Amherst Collaboration; Oxford Instrument Collaboration; Lawrence Berkeley National Lab Collaboration

    2013-03-01

    High-aspect-ratio sub-15 nm silicon trenches are fabricated directly from plasma etching of a block copolymer (BCP) mask. Polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) 40k-b-18k was spin coated and solvent annealed to form cylindrical structures parallel to the silicon substrate. The BCP thin film was reconstructed by immersion in ethanol and then subjected to an oxygen and argon reactive ion etching to fabricate the polymer mask. A low temperature ion coupled plasma with sulfur hexafluoride and oxygen was used to pattern transfer block copolymer structure to silicon with high selectivity (8:1) and fidelity. The silicon pattern was characterized by scanning electron microscopy and grazing incidence x-ray scattering. We also demonstrated fabrication of silicon nano-holes using polystyrene-b-polyethylene oxide (PS-b-PEO) using same methodology described above for PS-b-P2VP. Finally, we show such silicon nano-strucutre serves as excellent nano-imprint master template to pattern various functional materials like poly 3-hexylthiophene (P3HT).

  19. Nanomanufacturing of Gold Nanoparticle Arrays Using Peptide-Derivatized Block Copolymer Templates

    Science.gov (United States)

    Rao, Tingling; Singh, Gurpreet; Xie, Sibai; Karim, Alamgir; Becker, Matthew

    2013-03-01

    Collective surface plasmons (SPs) displayed by two-dimensional (2-D) Au nanostructures are important for applications such as plasmonics and plasmonic sensing. However, methods for fabricating programmable highly-ordered arrays of Au nanoparticles with nanoscale precision are limited. Here, we report a peptide--derivated block copolymer based rout towards continuous fabrication of Au nanoparticle superlatice with tunable structures. We successfully obtain discrete, hexagonally-packed Au nanoparticle hierarchical structures where Au-to-Au nanoparticle spacing is precisely controlled by the underlying PMMA cylindrical phase of the block copolymer (BCP). Dynamic thermal field processing techniques offer a facile and continuous rout to tune the BCP assembly, thus enabling versatile arrangement of Au nanostructures from Au-dots to Au-lines. Our method may open a cost-effective way towards assembly of 2-D Au nanoparticles with tunable structures by carefully tuning molecular parameters - a promising step to novel nanodevices. Akron Functional Materials Center (AFMC) and The University of Akron Research Foundation

  20. Enhanced Lateral Ordering in Cylinder Forming PS-b-PMMA Block Copolymers Exploiting the Entrapped Solvent.

    Science.gov (United States)

    Seguini, Gabriele; Zanenga, Fabio; Giammaria, Tommaso J; Ceresoli, Monica; Sparnacci, Katia; Antonioli, Diego; Gianotti, Valentina; Laus, Michele; Perego, Michele

    2016-03-30

    The self-assembly of block copolymer (BCP) thin films produces dense and ordered nanostructures. Their exploitation as templates for nanolithography requires the capability to control the lateral order of the nanodomains. Among a multiplicity of polymers, the widely studied all-organic polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) BCP can easily form nanodomains perpendicularly oriented with respect to the substrate, since the weakly unbalanced surface interactions are effectively neutralized by grafting to the substrate an appropriate poly(styrene-random-methyl methacrylate) P(S-r-MMA) random copolymer (RCP). This benefit along with the selective etching of the PMMA component and the chemical similarity with the standard photoresist materials deserved for PS-b-PMMA the role of BCP of choice for the technological implementation in nanolithography. This work demonstrates that the synergic effect of thermal annealing with the initial solvent naturally trapped in the basic RCP + BCP system after the deposition process can be exploited to enhance the lateral order. The solvent content embedded in the total RCP + BCP system can be tuned by changing the molecular weight and thus the thickness of the grafted RCP brush layer, without introducing external reservoirs or dedicated setup and/or systems. The appropriate supply of solvent supports a grain coarsening kinetics following a power law with a 1/3 growth exponent for standing hexagonally ordered cylinders. PMID:26959626