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Sample records for immiscible polymer blends

  1. Can Nanorods Emulsify Immiscible Polymer Blends?

    NASA Astrophysics Data System (ADS)

    Hore, Michael J. A.

    2005-03-01

    The addition of nanoscale rods to immiscible binary polymer blends has a pronounced effect on the dynamics of phase separation. The results of computer simulations of the Dissipative Particle Dynamics (DPD) model in three dimensions (3D) indicate that when nanorods prefer one of two components in an immiscible binary polymer blend, the rate of phase separation decreases when the volume fraction of nanorods is increased, or as the aspect ratio (L/D) of the rods is increased. Interestingly, anisotropic nanoparticles have a much more pronounced effect on phase separation dynamics in the system when compared to the effects of spherical nanoparticles, which, generically, do not alter the characteristics of the kinetics in the system. In particular, it may be the case that at high volume fractions -- or alternatively, low volume fractions and large aspect ratio of nanorods -- the system may undergo micro-phase separation only, indicating that the nanorods may be excellent emulsifying agents.

  2. Gas Separation Membranes Derived from High-Performance Immiscible Polymer Blends Compatibilized with Small Molecules.

    PubMed

    Panapitiya, Nimanka P; Wijenayake, Sumudu N; Nguyen, Do D; Huang, Yu; Musselman, Inga H; Balkus, Kenneth J; Ferraris, John P

    2015-08-26

    An immiscible polymer blend comprised of high-performance copolyimide 6FDA-DAM:DABA(3:2) (6FDD) and polybenzimidazole (PBI) was compatibilized using 2-methylimidazole (2-MI), a commercially available small molecule. Membranes were fabricated from blends of 6FDD:PBI (50:50) with and without 2-MI for H2/CO2 separations. The membranes demonstrated a matrix-droplet type microstructure as evident with scanning electron microscopy (SEM) imaging where 6FDD is the dispersed phase and PBI is the continuous phase. In addition, membranes with 2-MI demonstrated a uniform microstructure as observed by smaller and more uniformly dispersed 6FDD domains in contrast to 6FDD:PBI (50:50) blend membranes without 2-MI. This compatibilization effect of 2-MI was attributed to interfacial localization of 2-MI that lowers the interfacial energy similar to a surfactant. Upon the incorporation of 2-MI, the H2/CO2 selectivity improved remarkably, compared to the pure blend, and surpassed the Robeson's upper bound. To our knowledge, this is the first report of the use of a small molecule to compatibilize a high-performance immiscible polymer blend. This approach could afford a novel class of membranes in which immiscible polymer blends can be compatibilized in an economical and convenient fashion.

  3. On the coarsening of immiscible polymer blends with cocontinuous morphologies

    NASA Astrophysics Data System (ADS)

    Lopez-Barron, Carlos Rene

    Cocontinuous blends are used in a number of applications, including porous media for filtration, dessicant entrained polymers and substrates for drug delivery devices. A major drawback of these materials is that they are thermodynamically unstable, which implies that their morphology evolves into coarser structures when they are above their glass transition (or melting) temperatures. The mechanisms involved in the coarsening process are not fully understood yet. Three aspects of the coarsening process were addressed in this work: (1) thorough characterization of the microstructure during coarsening via the implementation of novel 3D imaging techniques, (2) modification of interfacial properties via addition of block copolymers in order to hinder the coarsening, and (3) determination of the connection between morphology and viscoelastic response during the coarsening process. Laser scanning confocal microscopy (LSCM) was used to image fluorescently labeled polystyrene (FLPS)/styrene-ran-acrylonitrile copolymer (SAN) blends. A methodology to obtain 3D micrographs of the blends and analyzed them to extract information of the geometry (size and local curvatures), topology (connectivity) and anisotropy (normal vectors) was implemented. From the analysis of the time evolution of the size and local curvature of the interface, two regimes of coarsening were identified: an early regime, where the characteristic size grows linearly with time and the interface evolves in a self-similar manner, and a late regime where the surface growth is neither linear nor self-similar. The measured decrease of the interface curvature was used to explain this regime transition. Symmetric diblock copolymers (BC) made of polystyrene (PS) and polymethyl methacrylate (PMMA) were used to compatibilize the blends. A dramatic decrease in the rate of coarsening was observed after adding just 1% of BC. The stabilization was particularly good for BC with an intermediate molecular weight. This result

  4. A new insight into interfaces of immiscible binary polymer blends from the free volume approach

    NASA Astrophysics Data System (ADS)

    Ramya, P.; Meghala, D.; Pasang, T.; Raj, J. M.; Chandrashekara, M. N.; Ranganathaiah, C.

    2012-06-01

    The interface width in an immiscible (PVC/PS) polymer blend is determined using hydrodynamic interaction parameter (α) derived from free volume data measured using Positron lifetime spectrometer. CONTIN program has been employed to get the free volume hole size distribution. A new definition of interface width is presented, which originates from the Kirkwood-Riseman theory and friction coefficient as per Stokes equation. Friction at the interface of a binary blend decides how close the surfaces come or stay farther resulting in narrow or broad interface width respectively.

  5. Advances in the engineering science of immiscible polymer blends: A powder route for delicate polymer precursors and a highly renewable polyamide/terephthalate blend system

    NASA Astrophysics Data System (ADS)

    Giancola, Giorgiana

    Powder processing of thermoplastic polymer composites is an effective way to achieve a high level of component homogenization in raw blends prior to melt processing, thus reducing the thermal and shear stress on the components. Polymer blends can be prepared that would otherwise not be possible due to thermodynamic incompatibility. Evaluation of this concept was conducted by processing PMMA and HDPE micron sized powders which were characterized using DSC and rheology. Optical microscopy and SEM, showed that high-quality, fine domain sized blends can be made by the compression molding process. Silica marker spheres were used to qualitatively assess the level dispersive mixing. EDS chemical analysis was effective in providing image contrast between PMMA and HDPE based on the carbonyl and ester oxygen. EDS image maps, combined with secondary electron images show that compression molding of blended powder precursors produces composites of comparable homogeneity and domain size as extrusion processing. FTIR proved valuable when assessing the intimacy of the constituents at the interface of the immiscible domains. The formation of an in-situ, PMMA nano-network structure resulting from solvent extraction and redeposition using DMF was uniquely found on the surface of these immiscible polymer blends. This work has shown that powder processing of polymers is an effective means to melt processed fragile polymers to high quality blends. Recently, efforts towards the development of sustainable materials have evolved due in part to the increase in price and limited supply of crude oil. Immiscible polymer blending is a paradigm that enables synergistic material performance in certain instances where the composite properties are superior to the sum of the constituents. The addition of PA6,10 to PTT offers an opportunity to increase the bio-based content of PTT while simultaneously maintaining or improving mechanical properties. PA6,10 and PTT are immiscible polymers that can be

  6. Effect of Particles on Rheology and Morphology of Immiscible PI/PDMS Polymer Blends

    NASA Astrophysics Data System (ADS)

    Thareja, Prachi; Velankar, Sachin S.

    2008-07-01

    We present the effects of several interfacially-active particles on the rheology of model immiscible polymer blends of polyisoprene (PI) and polydimethylsiloxane (PDMS) with a droplet-matrix morphology. The particles are capable of adsorbing at the PI/PDMS interface, and hence addition of these particles is expected to significantly affect the breakup and coalescence of drops and consequently the drop size. Using rheology (specifically, strain recovery upon cessation of shear) as a tool to probe morphological evolution, we show that none of the particles are able to prevent coalescence of the drops, at least at a particle loading of 0.5 vol.%. Remarkably however, some particle types strongly promote coalescence in some blends.

  7. Physical properties of immiscible polymers

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    The demixing of immiscible polymers in low gravity is discussed. Applications of knowledge gained in this research will provide a better understanding of the role of phase segregation in determining the properties of polymer blends made from immiscible polymers. Knowledge will also be gained regarding the purification of biological materials by partitioning between the two liquid phases formed by solution of the polymers polyethylene glycol and dextran in water. Testing of new apparatus for space flight, extension of affinity phase partitioning, refinement of polymer chemistry, and demixing of isopycnic polymer phases in a one gravity environment are discussed.

  8. Effects of shear during the cooling on the rheology and morphology of immiscible polymer blends

    NASA Astrophysics Data System (ADS)

    Hammani, S.; Moulai-Mostefa, N.; Benyahia, L.; Tassin, J. F.

    2014-08-01

    The aim of this work was the generation of a microfibrillar structure in immiscible polymer blends using a new technique. The blend polymer model is the emulsion formed by a mixture of polypropylene (PP) with polystyrene (PS) in the proportion of PP10/PS90. In the first case the pellets of polystyrene and polypropylene were blended on the twin-screw mini extruder in the classical manner with different shear rates. In the second case, the same blend was prepared in the same way followed by a dynamic cooling at different shear rates. The phase morphologies of PP in the blend were determined by Scanning Electron Microscopy on two directions (transversal and longitudinal direction to the flow). In the two cases, the dispersed phase size decreased with the increase of the shear rate in the extruder. An anomaly was registered in the classical method at 200 rpm, where the size of the dispersed phase increases with the increase of the shear rate. The dynamic cooling technique recorded smaller diameters (4 to 5 times) of the dispersed phase compared to the conventional technique. In addition, the reappearance of the microfilaments at 200rpm was observed. The rheological properties were determined by RS100 (Thermo Scientific Haake). Using this new technique, it was noticed that he elastic modulus increases with one decade compared to the classical method and the complex viscosity decreases with the increase of the shear rate. An anomaly was registered in the classical technique, where the dynamic viscosity at 200rpm increases with increasing the shear rate in the extruder.

  9. Morphology Evolution of Polypropylene in Immiscible Polymer Blends for Fabrication of Nanofibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immiscible blends of cellulose acetate butyrate (CAB) and isotactic polypropylenes (iPPs) with different melting index were extruded through a two-strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios by controlling the drawing speed. The morphologies of iPP fibers e...

  10. Tailoring the interface of an immiscible polymer blend by a mutually miscible homopolymer grafted onto graphene oxide: outstanding mechanical properties.

    PubMed

    Kar, Goutam Prasanna; Biswas, Sourav; Bose, Suryasarathi

    2015-01-21

    A unique strategy was adopted here to improve the compatibility between the components of an immiscible polymer blend and strengthen the interface. PMMA, a mutually miscible polymer to both PVDF and ABS, improved the compatibility between the phases by localizing at the blends interface. This was supported by the core-shell formation with PMMA as the shell and ABS as the core as observed from the SEM micrographs. This phenomenon was strongly contingent on the concentration of PMMA in the blends. This strategy was further extended to localize graphene oxide (GO) sheets at the blends interface by chemically coupling it to PMMA (PMMA-g-GO). A dramatic increment of ca. 84% in the Young's modulus and ca. 124% in the yield strength was observed in the presence of PMMA-g-GO with respect to the neat blends. A simultaneous increment in both the strength and the modulus was observed in the presence of PMMA-g-GO whereas, only addition of GO resulted in a moderate improvement in the yield strength. This study reveals that a mutually miscible polymer can render compatibility between the immiscible pair and can improve the stress transfer at the interface.

  11. Time dependence of the mechanical properties of an immiscible polymer blend

    NASA Astrophysics Data System (ADS)

    Lynch, Jennifer Krystyna

    Lifetime of a 35/65 PS/HDPE immiscible polymer blend, IMPB, railroad crosstie was investigated. Predictive techniques were developed to predict creep and stress relaxation behavior from short-term compressive stress-strain experiments, and predicted values were compared with experimental results. The weathering effect on the IMPB mechanical properties and the environmental benefits of replacing chemically treated wood crossties with IMPB crossties were investigated. Creep and stress relaxation experiments were performed under conditions simulating the maximum lateral load acting on a crosstie on a Class 1 railroad, and spike pull out experiments were performed using cut spikes. Cyclic uniaxial compressive creep experiments left nearly no residual strain remaining in the IMPB samples. Experimental results suggest the track gage will not widen more than 1/8 of an inch when IMPB crossties are utilized. Thus, creep and track gage widening do not limit the lifetime of IMPB crossties in track. Uniaxial compressive stress relaxation experiments and spike pull out experiments conducted at various time intervals from the day of installation were performed to illustrate the similarity of a spike pull out force versus time from the day of installation curve and a stress relaxation curve. The force decreases exponentially with time, in both cases. Research determined that spike killing due to biological attack is irrelevant, and there is no evidence of spike killing on any IMPB crossties currently in track. Predicted creep strain and stress relaxation were in good agreement with experimental data. A correlation is drawn between predicted long-term creep behavior for the IMPB and experimental creep behavior of polyethylene over 25 years. Theories developed for this work were determined reasonable and provide an alternative to performing long-term experiments. Natural and accelerated weathering experiments indicated no degradation in IMPB mechanical properties. Accelerated

  12. Solvent-free Fabrication of Tissue Engineering Scaffolds with Immiscible Polymer Blends

    PubMed Central

    Ma, Liang; Jiang, Wei; Li, Wei

    2014-01-01

    A completely organic solvent-free fabrication method is developed for tissue engineering scaffolds by gas foaming of immiscible polylactic acid (PLA) and sucrose blends, followed by water leaching. PLA scaffolds with above 90% porosity and 25–200 μm pore size were fabricated. The pore size and porosity was controlled with process parameters including extrusion temperature and foaming process parameters. Dynamic mechanical analysis showed that the extrusion temperature could be used to control the scaffold strength. Both unfoamed and foamed scaffolds were used to culture glioblastoma (GBM) cells M059K. The results showed that the cells grew better in the foamed PLA scaffolds. The method presented in the paper is versatile and can be used to fabricate tissue engineering scaffolds without any residual organic solvents. PMID:24764605

  13. Towards ultraporous poly(L-lactide) scaffolds from quaternary immiscible polymer blends.

    PubMed

    Virgilio, N; Sarazin, P; Favis, B D

    2010-08-01

    Ultraporous poly(l-lactide) (PLLA) scaffolds were prepared by melt-processing quaternary ethylene propylene diene rubber/poly(epsilon-caprolactone)/polystyrene/poly(l-lactide) (EPDM/PCL/PS/PLLA) 45/45/5/5 %vol. polymer blends modified with a PS-b-PLLA diblock copolymer. The morphology consists of a PS+PLLA+copolymer sub-blend layer forming at the interface of the EPDM and PCL phases. Quiescent annealing and interfacial modification using the block copolymer are used to control the blend microstructure. The ultraporous structure is subsequently obtained by selectively extracting the EPDM, PS and PCL phases. The PLLA scaffolds modified with the PS-b-PLLA copolymer present themselves as fully interconnected porous networks with asymmetric channel walls, one side being smooth while the other is covered with an array of submicron-sized PLLA droplets. They are prepared with a high degree of control over the pore size, with averages ranging from 5microm to over 100microm and a specific surface from 9.1 to 23.1m(2)/g of PLLA, as annealing is carried out from 0 to 60min. The void volume reaches values as high as 95% and in all cases the shape and dimensions of the scaffolds are maintained with a high level of integrity. The proposed method represents a comprehensive approach towards the design and generation of porous PLLA scaffolds based on complex morphologies from melt-processed multiphase polymer systems.

  14. Radiation effects on the immiscible polymer blend of nylon1010 and high-impact strength polystyrene (II): mechanical properties and morphology

    NASA Astrophysics Data System (ADS)

    Dong, Wenfei; Chen, Guangxin; Zhang, Wanxi

    2001-03-01

    The paper studies the morphology and mechanical properties of immiscible binary blends of the nylon 1010 and HIPS through the radiation crosslinking method. In this blend, the HIPS particles were the dispersed phases in the nylon1010 matrix. With increasing of dose, the elastic modulus increased. However, the tensile strength, elongation at break and the energy of fracture increased to a maximum at a dose of 0.34 MGy, then reduced with the increasing of dose. SEM photographs show that the hole sizes are not changed obviously at low dose and at high dose, remnants that cannot be dissolved in formic acid and THF can be observed in the holes and on the surface. TEM photographs showed that radiation destroys the rubber phases in the polymer blend.

  15. Binary Polymer Brushes of Strongly Immiscible Polymers.

    PubMed

    Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

    2015-06-17

    The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

  16. Mixing of immiscible polymers using nanoporous coordination templates

    NASA Astrophysics Data System (ADS)

    Uemura, Takashi; Kaseda, Tetsuya; Sasaki, Yotaro; Inukai, Munehiro; Toriyama, Takaaki; Takahara, Atsushi; Jinnai, Hiroshi; Kitagawa, Susumu

    2015-07-01

    The establishment of methodologies for the mixing of immiscible substances is highly desirable to facilitate the development of fundamental science and materials technology. Herein we describe a new protocol for the compatibilization of immiscible polymers at the molecular level using porous coordination polymers (PCPs) as removable templates. In this process, the typical immiscible polymer pair of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) was prepared via the successive homopolymerizations of their monomers in a PCP to distribute the polymers inside the PCP particles. Subsequent dissolution of the PCP frameworks in a chelator solution affords a PSt/PMMA blend that is homogeneous in the range of several nanometers. Due to the unusual compatibilization, the thermal properties of the polymer blend are remarkably improved compared with the conventional solvent-cast blend. This method is also applicable to the compatibilization of PSt and polyacrylonitrile, which have very different solubility parameters.

  17. Thin film fabrication of PMMA/MEH-PPV immiscible blends by corona discharge coating and its application to polymer light emitting diodes.

    PubMed

    Jung, Hee Joon; Park, Youn Jung; Choi, Sang Hun; Hong, Jae-Min; Huh, June; Cho, Jun Han; Kim, Jung Hyun; Park, Cheolmin

    2007-02-13

    We introduce a new and facile process, corona discharge coating (CDC), to fabricate thin polymer films of the immiscible poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and poly(methyl methacrylate) (PMMA) blends. The method is based on utilizing directional electric flow, known as electric wind, of the charged unipolar particles generated by corona discharge between a metallic needle and a bottom plate under high electric field (5-10 kV/cm). The electric flow rapidly spreads out the polymer solution on the bottom plate and subsequently forms a smooth and flat thin film over a large area within a few seconds. The method is found to be effective for fabricating uniform thin polymer films with areas larger than approximately 30 mm2. The thin films obtained by CDC exhibit unique microstructures where well-defined spherical and cylindrical domains of approximately 50 nm in diameter coexist. These nanosized domains are found to be much smaller than those in films made by conventional spin coating, which suggests that CDC is beneficial for fabricating phase-separated thin film structures with significantly increased interfacial areas. The effects of the applied voltage, tip-to-plate distance, and substrates on the film formation as well as the resulting microstructure are investigated. Furthermore, the light emitting performance of a device prepared by CDC is compared with one made by spin coating.

  18. Design of electrical conductive composites: tuning the morphology to improve the electrical properties of graphene filled immiscible polymer blends.

    PubMed

    Mao, Cui; Zhu, Yutian; Jiang, Wei

    2012-10-24

    Polystyrene (PS) and poly(methyl methacrylate) (PMMA) blends filled with octadecylamine-functionalized graphene (GE-ODA) have been fabricated to obtain conductive composites with a lower electrical percolation threshold according to the concept of double percolation. The dependence of the electrical properties of the composites on the morphology is examined by changing the proportion of PS and PMMA. Our results reveal that the electrical conductivity of the composites can be optimal when PS and PMMA phases form a cocontinuous structure and GE-ODA nanosheets are selectively located and percolated in the PS phase. For the PS/PMMA blend (50w/50w), the composites exhibit an extremely low electrical percolation threshold (0.5 wt %) because of the formation of a perfect double percolated structure. Moreover, the rheological properties of the composites are also measured to gain a fundamental understanding of the relationship between microstructure and electrical properties.

  19. Process for blending coal with water immiscible liquid

    DOEpatents

    Heavin, Leonard J.; King, Edward E.; Milliron, Dennis L.

    1982-10-26

    A continuous process for blending coal with a water immiscible liquid produces a uniform, pumpable slurry. Pulverized raw feed coal and preferably a coal derived, water immiscible liquid are continuously fed to a blending zone (12 and 18) in which coal particles and liquid are intimately admixed and advanced in substantially plug flow to form a first slurry. The first slurry is withdrawn from the blending zone (12 and 18) and fed to a mixing zone (24) where it is mixed with a hot slurry to form the pumpable slurry. A portion of the pumpable slurry is continuously recycled to the blending zone (12 and 18) for mixing with the feed coal.

  20. Assembly of plate-like nanoparticles in immiscible polymer blends--effect of the presence of a preferred liquid-liquid interface.

    PubMed

    Filippone, Giovanni; Causa, Andrea; Salzano de Luna, Martina; Sanguigno, Luigi; Acierno, Domenico

    2014-05-14

    The assembly of lamellar (clay) nanoparticles in a blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with drop-matrix morphology is studied combining viscoelastic measurements and morphological analyses. A reference system based on pure PS is used to highlight the effect on the assembly process of the presence of liquid interfaces where the particles are inclined to gather. The filler content is varied in a wide range to cover all the possible structures, from isolated flocs up to space-spanning networks. The goal is to elucidate whether the particles govern the blend morphology or the structural evolutions of the fluids dictate the space arrangement of the filler. The PMMA drops anchor the lamellae frustrating their peculiar mobility in the polymer melt. On the other hand, the clay radically affects the blend morphology, inducing irregularly-shaped drops and drop clustering phenomena even in case of partial coverage of the drop surface. Above the critical filler content for the saturation of the polymer-polymer interface, a space-spanning particle network eventually builds up. Despite the embedding of the PMMA drops, such a superstructure exhibits the same features of those forming in homogeneous mediums, enabling the use of approaches conceived for systems with single-phase matrix. Compared to the latter, the percolation and fractal models reveal subtle and yet meaningful differences in terms of stress-bearing mechanisms and structure of the building blocks which constitute the network.

  1. Development of an immiscible polymer/polymer/nanoparticle system in order to study the location of nanoparticles at polymer/polymer interface by quantitative optical microscopy

    NASA Astrophysics Data System (ADS)

    Johansen, Luis Henrique B.; Canto, Leonardo B.; Canevarolo, Sebastião V.

    2015-12-01

    In the past ten years, stabilization of the phase morphology of immiscible polymer blends during melt compounding went through a new perspective by the use of inorganic nanoparticles as compatibilizers. Following the ideas of Ramsden and Pickering, the stabilization of the minor phase in immiscible polymer blends could be achieved with solid nanoparticles located at the interface of the phases, lowering the interfacial tension and acting as a physical barrier to droplet coalescence. In this work, the location of the silica nanoparticle in an immiscible polymer blend is studied using quantitative optical microscopy, measuring the total light scattering, i.e. turbidity, created by the use of hydrophilic and hydrophobic silica nanoparticles (hi-silica and hb-silica, respectively) in an immiscible polymer blend. The light scattering at the polymer/polymer interface is minimized choosing a PS/PC immiscible blend which has minimal difference in their refractive indices. On the other hand, the considerable difference in the refractive index of the chosen polymers and nanosilica would highlight the scattering effect of the silica nanoparticles if located at the polymer/polymer interface. The transmitted light intensity from neat PS/PC blends and some PS/PC/hl-silica systems were similar, showing only a small change in the range of the glass transition temperatures of the two polymers, which is an indication that the silica nanoparticles are dispersed inside the two polymer phases. However, the transmitted light intensity is greatly changed in the system PS/PC/hb-silica, containing the hydrophobic silica, which according to the wetting parameter should have the silica nanoparticles located mainly at the polymer/polymer interface.

  2. Welding immiscible polymers with a supercritical fluid.

    PubMed

    Wang, Xiaochu; Sanchez, Isaac C

    2007-11-20

    Polymer adhesion between two immiscible polymers is usually poor because there is little interpenetration of one polymer into the other at the interface. Increasing the width of the interfacial zone can enhance adhesion and mechanical properties. In principle, this can be accomplished by exposing heterogeneous polymer materials to a high-pressure fluid. The fluid can act as a common solvent and promote interpenetration. It also increases chain mobility at the interface, which helps to promote "welding" of the two polymers. A combination of the gradient theory of inhomogeneous systems and the Sanchez-Lacombe equation of state was used to investigate this phenomenon, especially the effect of the high compressibility of supercritical (SC) fluid on the compatibilization of two incompatible polymers. We calculate the interfacial density profile, interfacial thickness, and interfacial tension between the two polymers with and without the SC fluid. We find that the interfacial tension is decreased and the interfacial thickness is increased with high-pressure SC fluid for the ternary systems we have investigated. As the critical point is approached and the SC compressibility becomes large, no enhancement or deleterious effects on compatibilization were observed.

  3. Electrostatic contributions in the increased compatibility of polymer blends.

    PubMed

    Linares, Elisângela M; Jannuzzi, Sergio A V; Galembeck, Fernando

    2011-12-20

    Successful blending of different polymers to make a structural or functional material requires overcoming limitations due to immiscibility and/or incompatibility that arise from large polymer-polymer interfacial tensions. In the case of latex blends, the combination of capillary adhesion during the blended dispersion drying stage with electrostatic adhesion in the final product is an effective strategy to avoid these limitations, which has been extended to a number of polymer blends and composites. This work shows that adhesion of polymer domains in blends made with natural rubber and synthetic latexes is enhanced by electrostatic adhesion that is in turn enhanced by ion migration, according to the results from scanning electric potential microscopy. The additional attractive force between domains improves blend stability and mechanical properties, broadening the possibilities and scope of latex blends, in consonance with the "green chemistry" paradigm. This novel approach based on electrostatic adhesion can be easily extended to multicomponent systems, including nonpolymers.

  4. Morphological development of polypropylene in immiscible blends with cellulose acetate butyrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Isotactic polypropylenes (iPP) with different melt flow indexes were melt blended with cellulose acetate butyrate (CAB) and then prepared into microspheres or nanofibers following a novel process of producing well dispersed CAB/iPP immiscible blends and subsequent removal of the CAB matrix. The morp...

  5. Porous Polyolefin Films via Polymer Blends

    NASA Astrophysics Data System (ADS)

    Macosko, Chris

    Porous polymer films have broad application including battery separators, membrane supports and filters. Polyolefins are attractive for these applications because of their solvent resistance, low electrical and thermal conductivity, easy fabrication and cost. We will describe fabrication of porous films using cocontinuous blends of a polyolefin with another polymer which can be readily removed with a solvent. Methods to image and control the cocontinuous morphology will be presented.Bell, J. R., K. Chang, C. R. Lopez-Barron, C. W. Macosko, and D. C. Morse, ''Annealing of cocontinuous polymer blends: effect of block copolymer molecular weight and architecture,'' Macromolecules 43, 5024-5032 (2010).Lopez-Barron, C. R., and C. W. Macosko, ''Direct measurement of interface anisotropy of bicontinuous structures via 3D image analysis,'' Langmuir 26, 14284-14293 (2010).Trifkovic, M., A. T. Hedegaard, K. Huston, M. Sheikhzadeh, and C. W. Macosko, ''Porous films via PE/PEO cocontinuous blends,'' Macromolecules 45, 6036-6044 (2012).Hedegaard, A.T., L.L. Gu and C. W. Macosko, ``Effect of Extensional Viscosity on Cocontinuity of Immiscible Polymer Blends'' J. Rheol. 59, 1397-1417 (2015).

  6. Miscible polymer blend dynamics

    NASA Astrophysics Data System (ADS)

    Pathak, Jai Avinash

    The segmental and terminal dynamics of miscible polymer blends have been systematically investigated with pointed experiments to test dichotomous literature ideas on the origin of dynamic heterogeneity in these systems. Segmental dynamics have been studied by dielectric spectroscopy, while terminal dynamics have been studied by oscillatory shear rheology. It has been found that when composition fluctuations are suppressed, dynamic heterogeneities, such as the failure of time-temperature superposition (tTS), are also suppressed. This observation lends credence to the ideas of Fischer and Kumar that spontaneous composition fluctuations in miscible blends profoundly affect their segmental dynamics. In addition, data acquired in this study on two model weakly-interacting miscible polyolefin blends, were combined with literature data to show that breakdown of tTS worsens with increasing dynamic asymmetry (intrinsic differences in component dynamics) in weakly-interacting miscible blends. This observation is adduced as evidence for the role of dynamic asymmetry in miscible blend dynamics, in addition to the role of composition fluctuations. Finally, attempts were made to use information on component segmental dynamics, as obtained from the composition fluctuation model of Kumar, to predict terminal dynamics in miscible blends. In this regard, the composition fluctuation model was first used to model segmental dynamics in a model weakly-interacting blend. Then, experimental segmental and terminal dynamics data were used to identify a possible segmental time-scale which may control terminal relaxation of a chain in a blend. This timescale was found to lie on the long-time end of the distribution of segmental relaxation times for each component. It was calculated from the segmental relaxation time distribution for each component of a miscible blend as the average-longest segmental time experienced by the monomers of a given chain. Using the Doi-Edwards tube model, the

  7. Compatibilization of All-Conjugated Polymer Blends for Organic Photovoltaics.

    PubMed

    Lombeck, Florian; Sepe, Alessandro; Thomann, Ralf; Friend, Richard H; Sommer, Michael

    2016-08-23

    Compatibilization of an immiscible binary blend comprising a conjugated electron donor and a conjugated electron acceptor polymer with suitable electronic properties upon addition of a block copolymer (BCP) composed of the same building blocks is demonstrated. Efficient compatibilization during melt-annealing is feasible when the two polymers are immiscible in the melt, i.e. above the melting point of ∼250 °C of the semicrystalline donor polymer P3HT. To generate immiscibility at these high temperatures, the acceptor polymer PCDTBT is equipped with fluorinated side chains leading to an increased Flory-Huggins interaction parameter. Compatibilization in bulk and thin films is demonstrated, showing that the photovoltaic performance of pristine microphase separated and nanostructured BCPs can also be obtained for compatibilized blend films containing low contents of 10-20 wt % BCP. Thermodynamically stable domain sizes range between several tens of microns for pure blends and ∼10 nm for pure block copolymers. In addition to controlling domain size, the amount of block copolymer added dictates the ratio of edge-on and face-on P3HT crystals, with compatibilized films showing an increasing amount of face-on P3HT crystals with increasing amount of compatibilizer. This study demonstrates the prerequisites and benefits of compatibilizing all-conjugated semicrystalline polymer blends for organic photovoltaics.

  8. Bismaleimide/Preceramic Polymer Blends for Hybrid Material Transition Regions. Part 1. Processing and Characterization (Postprint)

    DTIC Science & Technology

    2014-01-01

    Case Number: 88ABW-2012-4313; Clearance Date: 08 Aug 2012. Journal article published in High Performance Polymers, 25(4), 363-376 (2013). © 2012 Sage...thermal properties, and rheology of the blends. Preparation of hot-melt blends Two types of samples were prepared. The first group was mixed and then...siloxanes to silicon carbide. Chem Mater 1992; 4: 1313–1323. 12. Elias L, Fenouillot F, Majeste JC, et al. Morphology and rheology of immiscible polymer

  9. Advanced materials based on polymer blends/polymer blend nanocomposites

    NASA Astrophysics Data System (ADS)

    Shikaleska, A. V.; Pavlovska, F. P.

    2012-09-01

    Processability, morphology, mechanical properties and rheological behavior of poly(vinylchloride) (PVC)/poly(ethylmethacrylate) (PEMA) blends and PVC/PEMA/montmorillonite (MMT) composites, prepared by melt processing in a brabender mixer, were studied. Samples were characterized using SEM, mechanical testing, DMTA and a parallel plate rheometer. Plastograms show that there is noticeable drop of fusion times and increase in melt viscosity torque of both, polymer blend and polymer blend nanocomposite, in comparison with those of neat PVC. SEM images show that homogenous dispersions are obtained. Tensile tests indicate that PVC/PEMA and PVC/PEMA/MMT samples have greater tensile strength and elastic modulus and lower elongation compared to PVC. When solid viscoelastic properties are considered (DMTA), slightly higher storage moduli are obtained whereas more prominent increase of storage modulus is observed when nanoclay particles are added in a PVC/PEMA matrix. From the calculated area of tandelta peak of all tested samples, nanocomposites exhibit the lowest damping behavior. Oscillatory measurements in a molten state were used for determining the frequency dependencies of storage G' and loss G" moduli. It was found that G" curves of neat PVC lie above those of G' suggesting that PVC behaves like viscoelastic liquid. Similar results, but with significantly higher values of G' and G" over the whole frequency range for PVC/PEMA blends were obtained. Steady shear measurements show that the presence of PEMA and nanoclay particles increases the shear stress and shear viscosity of neat PVC. In order to define the rheological equations of state the three material functions were determined. According to these functions all samples exhibit shear thinning behavior and the curves obey the power law equation. As rheological behaviour was found to be strongly dependent on blend's micro and macro structure and it is one of the main factors defining the end properties, attempt was

  10. Fabrication of Tunable Submicro- or Nano-structured Polyethylene Materials form Immiscible Blends with Cellulose Acetate Butyrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low density polyethylene (LDPE) was prepared into micro- or submicro-spheres or nanofibers via melt blending or extrusion of cellulose acetate butyrate (CAB)/LDPE immiscible blends and subsequent removal of the CAB matrix. The sizes of the PE spheres or fibers can be successfully controlled by varyi...

  11. Reactive Processing with Difunctional Oligomers to Increase Interfacial Adhesion in Polymer Blends

    NASA Astrophysics Data System (ADS)

    O'Brien, Charles; Rice+, Kevin; Dadmun, Mark

    2000-03-01

    The intoduction of blocky copolymers represents a possible method of compatibilizing two immiscible polymers in a blend. However, copolymers do not diffuse quickly to the interface of a polymer blend system. Therefore, reactive processing is being investigated as a means to form in-situ compatibilizers for polymer blends. A model system composed of poly(bisphenol A-co-epichlorohydrin) blended with poly(ethylene oxide) that is compatibilized with difunctional oligomers that are the same structure as the blend components is currently under investigation. It is expected that the oligomers can undergo an addition copolymerization during processing to create the blocky copolymers at the biphasic interface. Initial tensile measurements show that the addition of the reactive oligomers improves the properties of the blend. Additionally, preliminary results indicate that reactive oligomers may act as plasticizers and continue to polymerize at room temperature after the blend is removed from the melt mixer if insufficiently mixed.

  12. Molecular composites and polymer blends containing ionic polymers

    NASA Astrophysics Data System (ADS)

    Tsou, Li-Chun

    1997-11-01

    Polymer blends are generally immiscible due to the unfavorable thermodynamics of mixing. By the introduction of ion-dipole interaction, mechanical properties of the PPTA anion/polar polymers (such as PVP, PEO and PPrO) molecular composites have been investigated in relation to their miscibility and microstructural morphology. Optical clarity observed in the glassy PPTA anion/PVP system suggest the presence of miscibility, since the refractive indices between the two components are quite different, nsb{PVP} = 1.509 and nsb{PPTA} = 1.644. In general, the difference greater than 0.01 is sufficient to make blends opaque. DSC measurements, showing a composition dependent Tsb{g} and a melting temperature depression, also indicate the miscibility achieved at the molecular level, about 50-100 A. By using the Hoffman-Weeks plot, a negative Flory-Huggins interaction parameter, chi = -1.10, is obtained for the PPTA anion/PEO molecular composites. An irregular spherulitic pattern and a reduced crystal size suggest that PPTA anion is intimately mixed with the amorphous PEO, both inter- and intra-spherulitically. Molecular composites exhibit not only an enhanced tensile strength and modulus, but also a greater fracture toughness, Ksb{IC}, e.g., an 80% increase at a 2 wt% PPTA anion addition. An enhanced tensile strength associated with a reduced crystallinity suggests that PPTA anion is the major contributor to the superior tensile properties instead of the crystalline phase. Upon addition of PPTA anion to PPrO, a slower relaxation rate and a better thermal stability are observed. Significant enhancement is found when the monovalent K salt is replaced with a divalent Ca salt. The molecular reinforcement achieved via ion-dipole interactions is more effective than the rigid filler effect obtained in the non-ionic PPTA/PPrO blend: e.g., a modulus enhancement of 814% vs. 286%, as compared with the value for PPrO. Two phase systems with microphase separation are developed since many

  13. Polymer Blends. Volume 1

    DTIC Science & Technology

    1992-05-01

    polyimides, thereby potentially leading to a viable, new class of high temperature, thermoformable resins for 371 0C (7000F) applica- tions. The Polymer...PBI/PI systems exhibit miscibility which: - exhibit improved processibility over neat PBI - are thermoformable - have improved mechanical performance...new class of high temperature, thermoformable resins for 3710C (700*F) applications. The Polymer Alloy and Composite Program also established a

  14. Thermo-Gelation of Surface-Modified Polyethylene Microgels from Fragmentation and Immiscible Blends

    NASA Astrophysics Data System (ADS)

    Ling, Gerald H.; Shaw, Montgomery T.

    2008-07-01

    Polyethylene microgels were created by swollen-state grinding and ultrasonic fragmentation of bulk crosslinked polyethylene (XLPE) suspended in squalane, and by the extraction of crosslinked-polyethylene micro-domains from an immiscible blend of polyethylene (PE) and polystyrene (PS). Crosslinking of the polyethylene micro-domains in the blend was achieved by exposure to an electron beam. Suspensions of both microgels in squalane exhibit thermal gelation upon cooling where both G' and G″ increase by up to five-orders in magnitude when probed using small-angle oscillatory shear. We propose that this phenomenon is attributed to weak short-range interactions among the particles whereby surface terminal chains on the microgels can co-crystallize forming inter-particle bonds. However, these interactions are mild enough that the systems may be reverted to its original state by applying higher shear stresses at elevated temperatures.

  15. Characterization of interfaces in Binary and Ternary Polymer Blends by Positron Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ranganathaiah, C.

    2015-06-01

    A miscible blend is a single-phase system with compact packing of the polymeric chains/segments due configuration/conformational changes upon blending. Differential Scanning Calorimetry (DSC) is the most employed method to ascertain whether the blend is miscible or immiscible. Positron Lifetime Spectroscopy (PLS) has been employed in recent times to study miscibility properties of polymer blends by monitoring the ortho-Positronium annihilation lifetimes as function of composition. However, just free volume monitoring and the DSC methods fail to provide the composition dependent miscibility of blends. To overcome this limitation, an alternative approach based on hydrodynamic interactions has been developed to derive this information using the same o-Ps lifetime measurements. This has led to the development of a new method of measuring composition dependent miscibility level in binary and ternary polymer blends. Further, the new method also provides interface characteristics for immiscible blends. The interactions between the blend components has a direct bearing on the strength of adhesion at the interface and hence the hydrodynamic interaction. Understanding the characteristic of interfaces which decides the miscibility level of the blend and their end applications is made easy by the present method. The efficacy of the present method is demonstrated for few binary and ternary blends.

  16. Vorticity banding in biphasic polymer blends.

    PubMed

    Caserta, Sergio; Guido, Stefano

    2012-11-27

    Pattern formation under the action of flow is a subject of considerable scientific interest with applications going from microfluidics to granular materials. Here, we present a systematic investigation of shear-induced banding in confined biphasic liquid-liquid systems, i.e., formation of alternating regions of high and low volume fraction of droplets in a continuous phase (shear bands). This phenomenon is investigated in immiscible polymer blends sheared in a sliding parallel plate flow cell. Starting from a spatially uniform distribution of droplets, the formation of bands aligned along the flow direction is observed, eventually leading to an almost complete separation between droplet-rich and continuous phase regions. The initial band size is related to the gap dimension; the merging of bands and consequent spacing reduction has also been observed for long times. Shear banding is only observed when the viscosity of the dispersed phase is lower as compared to the continuous phase and in a limited range of the applied shear rate. Rheological measurements show that band formation is associated with a viscosity decrease with respect to the homogeneous case, thus implying that system microstructure is somehow evolving toward reduced viscous dissipation under flow.

  17. Controlled and high throughput fabrication of poly(trimethylene terephthalate) nanofibers via melt extrusion of immiscible blends

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immiscible blends of cellulose acetate butyrate (CAB) and poly(trimethylene terephthalate) (PTT) were melt extruded through a two strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios. PTT fibers were obtained by removal of the CAB matrix from the drawn extrudates, a...

  18. Controlled and high throughput fabrication of poly(trimethylene terphthalate) nanofibers via melt extrusion of immiscible blends

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immiscible blends of cellulose acetate butyrate (CAB) and poly(trimethylene terephthalate) (PTT) were melt extruded through a two strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios. PTT fibers were obtained by removal of the CAB matrix from the drawn extrudates, a...

  19. Immiscible solvents enabled nanostructure formation for efficient polymer photovoltaic cells.

    PubMed

    Lee, Dong-Hyun; Michael Yang, Yang; You, Jingbi; Richard, Eric; Li, Gang

    2014-07-25

    Organic photovoltaics (OPVs) fabricated via solution processing are an attractive way to realize low cost solar energy harvesting. Bulk heterojunction (BHJ) devices are the most successful design, but their morphology is less controllable. In this manuscript, we describe a simple approach to realize 'ordered' BHJ morphology using two immiscible solvents with different boiling point and a quasi-bilayer approach. Tunable fine structures were demonstrated in poly(3-hexylthiophene) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) model systems, and the devices with optimized fine structure showed a 33% efficiency enhancement compared to those with a planar bilayer structure.

  20. Two glass transitions in miscible polymer blends?

    SciTech Connect

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

    2014-06-28

    In contrast to mixtures of two small molecule fluids, miscible binary polymer blends often exhibit two structural relaxation times and two glass transition temperatures. Qualitative explanations postulate phenomenological models of local concentration enhancements due to chain connectivity in ideal, fully miscible systems. We develop a quantitative theory that explains qualitative trends in the dynamics of real miscible polymer blends which are never ideal mixtures. The theory is a synthesis of the lattice cluster theory of blend thermodynamics, the generalized entropy theory for glass-formation in polymer materials, and the Kirkwood-Buff theory for concentration fluctuations in binary mixtures.

  1. The use of Functionalized Nanoparticles as Non-specific Compatibilizers for Polymer Blends

    SciTech Connect

    W Zhang; M Lin; A Winesett; O Dhez; L Kilcoyne; H Ade; M rubinstein; K Shafi; A Ulman; et al.

    2011-12-31

    The ability to form blends of polymers offers the opportunity of creating a new class of materials with enhanced properties. In addition to the polymer components, recent advances in nanoengineering have resulted in the development of nanosized inorganic particles that can be used to improve the properties of the blend, such as the flammability and the mechanical properties. While traditional methods using copolymer compatibilizers have been used to strengthen polymer blends, here, we show that the inorganic nanosized filler additive can also serve as a compatibilizer as it can localize to the interface between the polymers. We use experimental and theoretical studies to show the fundamental mechanisms by which inorganic fillers with large aspect ratio and at least one-dimension in the nanometer range, can act as non-specific compatibilizers for polymer blends. We examine a series of nanosized fillers, ranging from nanotubes to nanoclays (with varying aspect ratios) in a model polystyrene (PS)/poly(methylmethacyralate) (PMMA) blend. Using a number of experimental techniques such as transmission electron microscopy (TEM), scanning tunneling X-ray microscopy (STXM), and atomic force microscopy (AFM) we postulate that the mechanism of compatibilization occurs as a result of the fillers forming in situ grafts with the immiscible polymers. We also use theoretical studies to show that the aspect ratio and the bending energy of the fillers play a key role in the compatibilization process. Our results indicate that the compatibilization is a general phenomenon, which should occur with all large aspect ratio nanofiller additives to polymer blends.

  2. Battery Separator from Polyphenylquinoxaline Polymer Blends.

    DTIC Science & Technology

    1978-04-01

    This work was performed to determine if polyphenylquinoxaline blends with polymers such as polyvinylacetate, cellulose acetate , can be made into...polymeric membranes useful as battery separators. It was found that polyphenylquinoxaline and cellulose acetate blends offer the best membrane useful as battery separators. (Author)

  3. Polymer blend compositions and methods of preparation

    DOEpatents

    Naskar, Amit K.

    2016-09-27

    A polymer blend material comprising: (i) a first polymer containing hydrogen bond donating groups having at least one hydrogen atom bound to a heteroatom selected from oxygen, nitrogen, and sulfur, or an anionic version of said first polymer wherein at least a portion of hydrogen atoms bound to a heteroatom is absent and replaced with at least one electron pair; (ii) a second polymer containing hydrogen bond accepting groups selected from nitrile, halogen, and ether functional groups; and (iii) at least one modifying agent selected from carbon particles, ether-containing polymers, and Lewis acid compounds; wherein, if said second polymer contains ether functional groups, then said at least one modifying agent is selected from carbon particles and Lewis acid compounds. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.

  4. Compatibilizing Bulk Polymer Blends by Using Organoclays

    NASA Astrophysics Data System (ADS)

    Si, Mayu; Gersappe, Dilip; Zhang, Wenhua; Ade, Harald; Rafailovich, Miriam; Sokolov, Jonathan; Rudomen, Gregory; Schwartz, Bradley; Fisher, Robert

    2004-03-01

    We investigated the compatiblizing performance of organoclays on melt mixed binary and tertiary polymer blends, such as, PS/PMMA, PC/SAN, PS/PMMA/PVC and PS/PMMA/PE. These polymer blends were characterized by TEM, STXM, DSC and DMA. TEM and STXM photographs show that the addition of organoclays into polymer blends drastically reduces the average domain size of the component phases. And the organoclay goes to the interfacial region between the different polymers and effectively slows down the domain size increasing during high temperature annealing. DMA and DSC results show the effect of organoclays on the mechanical properties and glass transitions temperature, which indicates the compatibilization on the molecular level. The generalized compatibilization induced by the nanoscale fillers for blends can be explained in terms of mean field models where the reduction of interfacial tension induced by in-situ grafting is counterbalanced by the increased bending energy due to the rigidity of the filler. This in turn can be shown to be a function of the degree of exfoliation, aspect ratio, and polymer filler interactions. Supported by NSF funded MRSEC at Stony Brook

  5. Thin films of photoactive polymer blends.

    PubMed

    Ruderer, Matthias A; Metwalli, Ezzeldin; Wang, Weinan; Kaune, Gunar; Roth, Stephan V; Müller-Buschbaum, Peter

    2009-03-09

    The morphology inside photoactive blended films of two conjugated homopolymers poly [(1-methoxy)-4-(2-ethylhexyloxy)-p-phenylene-vinylene] (MEH-PPV) and poly(3-hexylthiophene-2,5-diyl) (P3HT) is investigated. For both homopolymers a linear dependence of the installed film thickness from the concentration of the polymer solution used in spin coating is probed. This dependence allows preparation of an efficient series of blended films with constant thickness and different blending ratios. Information about the lateral structure inside the films is gained from grazing incidence small angle X-ray scattering. At the calculated critical blending ratio the smallest lateral separation between adjacent domains is found representing the highest surface contact between both homopolymers in the films. The presence of wetting layers at both interfaces as detected with X-ray reflectivity and atomic force microscopy is promising for photovoltaic applications. UV/Vis spectroscopy complements the structural investigation.

  6. Nanoscale control over phase separation in conjugated polymer blends using mesoporous silica spheres.

    PubMed

    Kelly, Timothy L; Yano, Kazuhisa; Wolf, Michael O

    2010-01-05

    A method of preparing blended conjugated polymer microparticles using mesoporous silica spheres is described. Poly(3,4-ethylenedioxythiophene) (PEDOT) was blended with poly(furfuryl alcohol) (PFA) by a sequential infiltration-polymerization approach. The materials were evaluated by both scanning and transmission electron microscopy and are shown to retain the overall spherical structure of the silica template. The filling of the mesopores and the polymer distribution within individual particles were determined by a combination of energy-dispersive X-ray microanalysis, X-ray photoelectron spectroscopy, and nitrogen adsorption. The results suggest that when PEDOT is added to the silica host, followed by PFA, the phase separation of the two immiscible polymers is constrained by the dimensions of the silica mesopores, ensuring nanoscale contact between the two phases. The silica template can be removed by etching with 25% hydrofluoric acid, leaving behind a blended polymer microparticle. The etched microparticles exhibit macroporous morphologies different from that of pure PEDOT particles prepared by a similar route. The blended microparticles also appear to undergo limited phase separation; no evidence for distinct polymer domains was observed. Conductivity measurements indicate that the blended particles are above the percolation threshold and support the conclusion that the phase domains are extremely small. Importantly, when PFA is added to the host first, followed by PEDOT, there is a striking difference to the final composition and morphology of the particles. This reversal of the blending order results in a more amorphous, phase-separated material. These results demonstrate the preparation of conjugated polymer blends with engineered nanoscale phase separation and may allow for future improvements in organic device architecture and performance.

  7. Engineering thermal conductivity in polymer blends

    NASA Astrophysics Data System (ADS)

    Rashidi, Vahid; Coyle, Eleanor; Kieffer, John; Pipe, Kevin

    Weak inter-chain bonding in polymers is believed to be a bottleneck for both thermal conductivity and mechanical strength. Most polymers have low thermal conductivity (~0.1 W/mK), hindering their performance in applications for which thermal management is critical (e.g., electronics packaging). In this work, we use computational methods to study how hydrogen bonding between polymer chains as well as water content can be used to engineer thermal transport in bulk polymers. We examine how changes in the number of hydrogen bonds, chain elongation, density, and vibrational density of states correlate with changes in thermal conductivity for polymer blends composed of different relative constituent fractions. We also consider the effects of bond strength, tacticity, and polymer chain mass. For certain blend fractions, we observe large increases in thermal conductivity, and we analyze these increases in terms of modifications to chain chemistry (e.g., inter-chain bonding) and chain morphology (e.g., chain alignment and radius of gyration). We observe that increasing the number of hydrogen bonds in the system results in better packing as well as better chain alignment and elongation that contribute to enhanced thermal conductivity. The Air Force Office of Scientific Research, Grant No. FA9550-14-1-0010.

  8. Phase Behavior of Ternary Polymer Blends: Asymmetry, Segregation Strength, and Coexisting Phases

    NASA Astrophysics Data System (ADS)

    Habersberger, Brian McLean

    The bicontinuous microemulsion phase, found in ternary polymer blends containing immiscible A and B homopolymers and an amphiphilic A-B diblock copolymer, has attracted interest due to its combination of properties that make it attractive for use as a template for nanoporous materials. While recent work has demonstrated that a variety of materials can be templated from a single blend system, future work may demand incorporation of a variety of polymers into microemulsion-forming blends. Such systems fall beyond the currently understood model phase behavior for ternary blends. In this thesis, the effect of well-controlled nonidealities and other extensions of ternary blend phase behavior are described. Systems were designed to investigate the influence of conformational asymmetry---a difference in the radius of gyration per molar volume of two polymers---on blend phase behavior. Previous work suggested that the influence was significant, and resulted in a broad region of a hexagonally symmetric phase in the vicinity of the microemulsion. This behavior could inhibit the process of capturing of microemulsion for templating purposes, so it is important to understand conformational asymmetry's influence. A related series of systems was designed to investigate the effect of increased segregation strength by using amphiphilic diblocks of varying molecular weight. Finally, a previous study incorporating an ABA triblock, C homopolymer, and ABABA--C amphiphilic hexablock was expanded to incorporate ordered components, allowing for hierarchical microphase separation. This study demonstrates that model ternary blend phase behavior can be extended to systems containing more complex linear polymer architectures. Additionally, two phenomena observed in these systems were investigated in detail. First, light scattering was observed in the vicinity of the order-disorder transition of blends; this scattering is a result of coexisting ordered and disordered phases. Finally, catalytic

  9. The study of multiphase polymer-blend morphologies by HVEM

    SciTech Connect

    Cavanaugh, T.J.; Nauman, E.B.; Buttle, K.; Turner, J.N.

    1996-12-31

    Multiphase polymer blends are important in the polymer industry. Most commercial blends consist of two main polymers combined with a third, compatibilizing polymer, typically a graft or block copolymer. The most common examples are those involving the impact modification of a brittle thermoplastic by the microdispersion of a rubber into the matrix. Recently, a model of ternary polymer blend has provided a wealth of morphologies for examination. Even though this model can give an excellent basis for the design of a polymer blend, experimental verification is necessary. A correlation of blend properties such as impact strength with blend morphology must also be made. The focus is to confirm the predicted morphologies in binary and ternary blends using HVEM.

  10. Phase Behavior of Polymer Blends for Organic Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Emerson, Jillian; Furst, Eric; Epps, Thomas, III

    2014-03-01

    Polymer blends offer a promising and economically-viable route to creating organic photovoltaic (OPV) devices, as blends can form bicontinuous domains via spinodal decomposition. Understanding the phase behavior of conjugated polymer blends commonly used in OPVs is vital to producing more efficient devices. In this work, we determined the Flory-Huggins solvent-polymer and polymer-polymer interaction parameters for a model system of poly(3-hexylthiophene) (P3HT) and polystyrene (PS) through solvent vapor swelling of thin polymer films. From these interaction parameters, we constructed a polymer/polymer/solvent phase diagram. The phase diagram was validated experimentally with solution-based transmission measurements of PS/P3HT. This work highlights a method to determine the phase behavior in polymer/polymer/solvent blends that can be extended to other combinations of macromolecules relevant to organic photovoltaics, composites, and other materials systems.

  11. Supramolecular assembly in telechelic polymer blends

    NASA Astrophysics Data System (ADS)

    Elliott, R.; Fredrickson, Glenn H.

    2009-10-01

    Equilibrium, supramolecular assembly in melt blends of two species of telechelic polymers with reversible bonding sites at both ends is theoretically investigated. The bonding between polymers, whether between like or dislike chains, is controlled by affinities of chain bonding set by specified bond energies. Low affinities, or low overall bond strength, results in a monodisperse population of unlinked chains while larger affinities cause longer chains to assemble, forming a polydisperse blend. We investigate sequentially blends with only homobonding (like chain), only heterobonding (dislike chain), and finally a mixed homo- and heterobonding melt. In the first case, the effects of longer chain assembly and polydispersity in a homogeneous melt and its bulk demixing transition are explored. In contrast with the homobonding case, large heterobonding affinities cause alternating blocks to assemble into multiblock copolymers, which can lead to mesophases. The weak bonding region between bulk phase separation and mesophase stability is investigated and a novel Lifshitz point is found indicating a region prone to emulsify. Mixed homo- and heterobonding systems are also examined. Polymeric segments of both species are modeled as flexible Gaussian threads and nonspecific interactions between dissimilar blocks are contactlike Flory-Huggins repulsions. The melts are assumed to be incompressible and all calculations are carried out within mean-field theory. A new integral equation formalism is developed for enumerating all linear species in these complex supramolecular systems, and the random phase approximation and numerical self-consistent field theory are invoked in this context to map out a variety of phase diagrams.

  12. Engineering Polymer Blends for Impact Damage Mitigation

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L.; Smith, Russell W.; Working, Dennis C.; Siochi, Emilie J.

    2016-01-01

    Structures containing polymers such as DuPont's Surlyn® 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn® 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.

  13. Dissolution behavior of a miscible polymer blend

    SciTech Connect

    Rodriguez, F.

    1996-12-31

    The orderly dissolution process with minimal swelling exhibited by poly(methyl methacrylate), PMMA, also is preserved in some blends of PMMA with other polymers. In the present work, dissolution rates for blends with up to 30 % poly(epichlorohydrin), PECH, have been measured in 4-methyl-2-pentanone at temperatures of 20 to 40{degrees}C. For films in the thickness range of 0.5 to 1 {mu}m, a laser interferometer yielded both the rate and the presence or absence of a transition layer at the polymer-solvent interface. The dissolution rate increases monotonically as the amount of PECH is increased. Beyond about 40% PECH, the dissolution process becomes less orderly. When a laser beam is reflected from a flat polymer film on a reflecting substrate like silicon, the reflected light intensity takes the form of a sinusoidal (or nearly sinusoidal) oscillation. The period of the oscillation can be related to the rate of dissolution. The amplitude of the oscillations gives a direct measure of refractive index of the polymer film. Changes in the amplitude (and, sometimes, the rate) give information about swelling. The offset between the maximum in the oscillations during dissolution compared to the reflectance of the bare wafer can be converted into a transition layer thickness although it is necessary to interpose a mathematical model for the concentration gradient in the layer. The most investigated {open_quotes}well-ordered{close_quotes} polymer is poly(methylmethacrylate), PMMA. Although primarily limited to lithography using electron beams or x-rays, PMMA continues to be a valuable reference polymer for dissolution studies.

  14. Generation of multicomponent polymer blend microparticles using droplet evaporation technique and modeling evaporation of binary droplet containing nonvolatile solute

    NASA Astrophysics Data System (ADS)

    Rajagopalan, Venkat Narayan

    Recently, considerable attention has been focused on the generation of nano- and micrometer scale multicomponent polymer particles with specifically tailored mechanical, electrical and optical properties. As only a few polymer-polymer pairs are miscible, the set of multicomponent polymer systems achievable by conventional methods, such as melt blending, is severely limited in property ranges. Therefore, researchers have been evaluating synthesis methods that can arbitrarily blend immiscible solvent pairs, thus expanding the range of properties that are practical. The generation of blended microparticles by evaporating a co-solvent from aerosol droplets containing two dissolved immiscible polymers in solution seems likely to exhibit a high degree of phase uniformity. A second important advantage of this technique is the formation of nano- and microscale particulates with very low impurities, which are not attainable through conventional solution techniques. When the timescale of solvent evaporation is lower than that of polymer diffusion and self-organization, phase separation is inhibited within the atto- to femto-liter volume of the droplet, and homogeneous blends of immiscible polymers can be produced. We have studied multicomponent polymer particles generated from highly monodisperse micrordroplets that were produced using a Vibrating Orifice Aerosol Generator (VOAG). The particles are characterized for both external and internal morphology along with homogeneity of the blends. Ultra-thin slices of polymer particles were characterized by a Scanning Electron Microscope (SEM), and the degree of uniformity was examined using an Electron Dispersive X-ray Analysis (EDAX). To further establish the homogeneity of the polymer blend microparticles, differential scanning calorimeter was used to measure the glass transition temperature of the microparticles obtained. These results have its significance in the field of particulate encapsulation. Also, better control of the

  15. How Pure Components Control Polymer Blend Miscibility

    NASA Astrophysics Data System (ADS)

    White, Ronald; Lipson, Jane; Higgins, Julia

    2012-02-01

    We present insight into some intriguing relationships revealed by our recent studies of polymer mixture miscibility. Applying our simple lattice-based equation of state, we discuss some of the patterns observed over a sample of experimental blends. We focus on the question of how much key information can one determine from a knowledge of just the pure components only, and further, on the role of separate enthalpic and entropic contributions to the miscibility behavior. One interesting correlation connects the value of the difference in pure component energetic parameters with that of the mixed segment interactions, suggesting new possibilities for predictive modeling. We also show how in some cases these two parameter groupings act as separate controls determining the entropy and enthalpy of mixing. Also discussed are the different patterns exhibited for UCST-type and LCST-type blends, these being revealed in some cases by simple examination of the underlying microscopic parameters.

  16. Compatibility and Impact Resistance of Biodegradable Polymer Blends Using Clays and Natural Nanotubes

    NASA Astrophysics Data System (ADS)

    Guo, Yichen; Yuan, Xue; Zuo, Xianghao; Rafailovich, Miriam

    Montmorillonite clays and Halloysite nanotubes (HNTs) were modified by surface adsorption of resorcinol di (phenyl phosphate) (RDP) oligomers. Biodegradable poly (lactic acid) (PLA) and poly (butylene adipate-co-butylene terephthalate) (PBAT) polymers were blended together with RDP coated clays and tubes. TEM images of thin sections indicated that even though both RDP coated clay nanotubes and platelets located on the interfacial region between two immiscible polymers, only the platelets, having the larger aspect ratio, were able to reduce the PBAT domain sizes. The ability of clay platelets to partially compatibilize the blend was further confirmed by the dynamic mechanical analysis (DMA) which showed that the glass transition temperatures of two polymers tend to shift closer. Izod impact testing demonstrated that the rubbery PBAT phase greatly increased the impact strength of the unfilled blend, but addition of only 5% of clay filler decrease the impact strength by nearly 50% while a small increase was observed with nanotubes at that concentration. A simple model is proposed. The clay platelets are observed to cover the interfacial area. Although they are effective at reducing the interfacial tension, they block the entanglements between two polymer phase and increase the overall brittleness. On the other hand, the HNTs are observed to lie perpendicular to the interface, which makes them less effective in reducing interfacial tension, but far more effective at retarding micro-crack propagation.

  17. Electron beam irradiation induced compatibilization of immiscible polyethylene/ethylene vinyl acetate (PE/EVA) blends: Mechanical properties and morphology stability

    NASA Astrophysics Data System (ADS)

    Entezam, Mehdi; Aghjeh, Mir Karim Razavi; Ghaffari, Mehdi

    2017-02-01

    Gel content, mechanical properties and morphology of immiscible PE/EVA blends irradiated by high energy electron beam were studied. The results of gel content measurements showed that the capability of cross-linking of the blend samples increased with an increase of the EVA composition. Also, the gel content for most compositions of the blends displayed a positive deviation from the additive rule. The results of mechanical properties showed that the tensile strength and elongation at break of the samples increased and decreased, respectively, with irradiation dose. On the other hand, the mechanical properties of the irradiated blends also depicted a positive deviation from additive rule contrary to the un-irradiated blends. A synergistic effect observed for the mechanical properties improvement of the irradiated blends and it was attributed to the probable formation of the PE-graft-EVA copolymers at the interface of the blends during the irradiation process. A theoretical analysis revealed that irradiation induced synergistic effect was more significant for EVA-rich blends with weaker interfacial interaction as compared to PE-rich blends. The morphological analysis indicated that the blend morphology was not affected obviously, whereas it was stabilized by irradiation.

  18. Reasons for using polymer blends in the electrospinning process

    NASA Astrophysics Data System (ADS)

    Martinova, Lenka; Lubasova, Daniela

    2012-11-01

    Polymer blends can be very effective for the processing of nanofibers, especially for the novel electrospinning process of Nanospider™ (Jirsak et al., 2005, www.nanospider.cz), offering the realistic potential for industrial production of nanofiber sheets. Polymer blending is designed to generate materials with optimized chemical, structural, mechanical, morphological and biological properties.

  19. Phase morphology and orientation development of polymer blends in melt processing

    NASA Astrophysics Data System (ADS)

    Yang, Jinhai

    In this dissertation, we studied phase morphology development of various polymer blends in both extrusion and melt spinning using scanning electron microscopy (SEM) assisted with appropriate etching techniques. Various processing conditions, for example shear or elongation rate, shear or elongation stress, and extrusion die length/diameter ratio were considered. The effects of material characteristics, such as viscosity ratio, miscibility and interfacial tension, were studied. To do this, polymer blends were carefully selected. One isotactic polypropylene was blended with two ethylene butene copolymers (EBM), which had different butene contents. One of the blends was miscible and the other was immiscible. The polypropylene was also blended two ethylene octene copolymers (EOM). The above blends had low interfacial tension and different viscosity ratios. One EBM was blended with two polyamide 12 (PA12) materials. These blends had high interfacial tension and different viscosity ratios. One maleic anhydride grafted ethylene octene copolymer was added into the EBM/PA12 blends to decrease their interfacial tension. Studies were focused on a phenomenon that the dispersed phases in these blends could coalesce into a surface layer in both extrusion and melt spinning. This process was controlled by viscosity ratio, interfacial tension and processing conditions. The orientation development of melt spun fibers of these blends was studied by both wide angle X-ray diffraction (WAXD) and birefringence techniques. The orientation was affected by both blend morphologies and solidification order of the blend individual phases. The phase, which solidifies later in the spinline, did not affect the orientation of the first solidified phase. However, the first solidified phase, if it was continuous phase, could largely suppress the orientation of the second solidified phase. Composite stress analysis explained the different orientation behaviors. Extrusion of a PA12 material through a

  20. Enhancing distributive mixing of immiscible polyethylene/thermoplastic starch blend through zeolite ZSM-5 compounding sequence.

    PubMed

    Thipmanee, Ranumas; Lukubira, Sam; Ogale, Amod A; Sane, Amporn

    2016-01-20

    The aim of this work was to explore the effect of zeolite ZSM-5 (ZSM5) incorporation sequence on the phase morphology, microstructure, and performance of polyethylene/thermoplastic starch (PE/TPS) films. Two processing sequences were used for preparing PE/TPS/ZSM5 composites at a weight ratio of PE to TPS of 70:30 and ZSM5 concentrations of 1-5 wt%: (i) melt compounding of PE with ZSM5 prior to melt blending with TPS (SI); and (ii) TPS was compounded with ZSM5 prior to blending with PE (SII). Distributive mixing and mechanical properties of PE/TPS blend were greatly enhanced when ZSM5 was incorporated via SII. These were caused by both the higher affinity between PE and ZSM5, compared to that of TPS and ZSM5, and the reduction of TPS viscosity after compounding with ZSM5, leading to migration of ZSM5 from TPS dispersed phase toward PE matrix and increase in breakup of TPS droplets during SII sequence.

  1. Improving the Compatibility and Mechanical Properties of Recycled Polymer Blends using Supercritical Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Fourman, Mitchell; Rafailovich, Miriam; Iraci, John Michael

    2011-03-01

    Supercritical Carbon Dioxide (scCO2) has been shown to decrease the interfacial tension between immiscible bulk polymer blends by Palermo et al. [Macromolecules 38 (22) 1980-1986, (2005)]. However, little work has been done to determine the efficacy of scCO2 on recycled materials. Here we show that scCO2 can be used to induce partial compatibility - and therefore improved mechanical properties - in bulk polymer blends using recycled materials. Blends of polymethyl methacrylate (PMMA), Ethylene vinyl acetate (EVA), and recycled Polyvinyl chloride (PVC) were created at different ratios using a CW Brabender twin screw extruder and exposed to scCO2. Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), Izod impact testing, and Instron tensile testing were used to measure the properties of blends before and after exposure. Results show improved strength and elasticity in bulk samples, with substantial improvement in modulus and impact factor within the ``density fluctuation ridge.'' Results suggest potential industrial and ecological benefits for scCO2. Supported in part by the Garcia NSF-MRSEC Center at the Department of Materials Science - Stony Brook University.

  2. Polymer blend lithography: A versatile method to fabricate nanopatterned self-assembled monolayers

    PubMed Central

    Huang, Cheng; Moosmann, Markus; Jin, Jiehong; Heiler, Tobias; Schimmel, Thomas

    2012-01-01

    Summary A rapid and cost-effective lithographic method, polymer blend lithography (PBL), is reported to produce patterned self-assembled monolayers (SAM) on solid substrates featuring two or three different chemical functionalities. For the pattern generation we use the phase separation of two immiscible polymers in a blend solution during a spin-coating process. By controlling the spin-coating parameters and conditions, including the ambient atmosphere (humidity), the molar mass of the polystyrene (PS) and poly(methyl methacrylate) (PMMA), and the mass ratio between the two polymers in the blend solution, the formation of a purely lateral morphology (PS islands standing on the substrate while isolated in the PMMA matrix) can be reproducibly induced. Either of the formed phases (PS or PMMA) can be selectively dissolved afterwards, and the remaining phase can be used as a lift-off mask for the formation of a nanopatterned functional silane monolayer. This “monolayer copy” of the polymer phase morphology has a topographic contrast of about 1.3 nm. A demonstration of tuning of the PS island diameter is given by changing the molar mass of PS. Moreover, polymer blend lithography can provide the possibility of fabricating a surface with three different chemical components: This is demonstrated by inducing breath figures (evaporated condensed entity) at higher humidity during the spin-coating process. Here we demonstrate the formation of a lateral pattern consisting of regions covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) and (3-aminopropyl)triethoxysilane (APTES), and at the same time featuring regions of bare SiOx. The patterning process could be applied even on meter-sized substrates with various functional SAM molecules, making this process suitable for the rapid preparation of quasi two-dimensional nanopatterned functional substrates, e.g., for the template-controlled growth of ZnO nanostructures [1]. PMID:23019558

  3. Effects of the Biodegradation on Biodegradable Polymer Blends and Polypropylene

    NASA Astrophysics Data System (ADS)

    Pereira, R. C. T.; Franchetti, S. M. M.; Agnelli, J. A. M.; Mattoso, L. H. C.

    2008-08-01

    The large use of plastics in the world generates a large amount of waste which persists around 200 years in the environment. To minimize this effect is important to search some new polymer materials: the blends of biodegradable polymers with synthetic polymers. It is a large area that needs an intensive research to investigate the blends properties and its behavior face to the different treatments to aim at the biodegradation. The blends used in this work are: some biodegradable polymers such as: poly(hydroxybutyrate) (PHB) and poly(ɛ-polycaprolactone) (PCL) with a synthetic polymer, polypropylene (PP), in lower concentration. These blends were prepared using an internal mixer (Torque Rheometer), and pressed. These films were submitted to fungus biotreatment. The films analyses will be carried out by Fourier Transform Infrared (FTIR), UV-Vis absorption (UV-Vis), Scanning Electronic Microscopy (SEM), DSC and TGA.

  4. Phase equilibria in polymer blend thin films: a Hamiltonian approach.

    PubMed

    Souche, M; Clarke, N

    2009-12-28

    We propose a Hamiltonian formulation of the Flory-Huggins-de Gennes theory describing a polymer blend thin film. We then focus on the case of 50:50 polymer blends confined between antisymmetric walls. The different phases of the system and the transitions between them, including finite-size effects, are systematically studied through their relation with the geometry of the Hamiltonian flow in phase space. This method provides an easy and efficient way, with strong graphical insight, to infer the qualitative physical behavior of polymer blend thin films.

  5. Blends of a Polymer of Intrinsic Microporosity and Partially Sulfonated Polyphenylenesulfone for Gas Separation.

    PubMed

    Yong, Wai Fen; Lee, Zhi Kang; Chung, Tai-Shung; Weber, Martin; Staudt, Claudia; Maletzko, Christian

    2016-08-09

    Polyphenylenesulfone (PPSU) and sulfonated polyphenylenesulfone (sPPSU) are widely used for liquid separations in the medical and food industries. However, their potential applications for gas separation have not been studied extensively owing to their low intrinsic gas permeability. We report here for the first time that blending with sPPSU can significantly improve the gas separation performance of highly permeable polymers of intrinsic microporosity (PIMs), specifically PIM-1, because of the strong molecular interactions of the sulfonic acid groups of sPPSU with CO2 and O2 . In addition, a novel co-solvent system has been discovered to overcome the immiscibility of these polymers. The presence of a higher degree of sulfonation in sPPSU results in better gas separation performance of the blend membranes close to or above the Robeson upper bound lines for O2 /N2 , CO2 /N2 and CO2 /CH4 separations. Interestingly, the blend membranes have comparable gas selectivity to sPPSU even though their sPPSU content is only 5-20 wt %. Moreover, they also display improved anti-plasticization properties up to 30 atm (3 MPa) using a binary CO2 /CH4 feed gas. The newly developed PIM-1/sPPSU membranes are potential candidates for air separation, natural gas separation, and CO2 capture.

  6. Photothermal and morphological characterization of PLA/PCL polymer blends

    NASA Astrophysics Data System (ADS)

    Correa-Pacheco, Z. N.; Jiménez-Pérez, J. L.; Sabino, M. A.; Cruz-Orea, A.; Loaiza, M.

    2015-09-01

    Nowadays, some synthetic polymers have been replaced by biodegradable polymers in order to avoid environmental contamination. Among these biodegradables polymers, aliphatic polyesters such as polylactic acid (PLA) and polycaprolactone (PCL) have been widely used. In the present study, solvent-casting films of PLA, PCL and polymer blends with and without compatibilizer (PLA grafted with maleic anhydride) were prepared. The thermal diffusivity ( α) of each sample was obtained by using the open photoacoustic cell technique. Morphology and thermal properties were determined by using scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry (DSC), respectively. The blends showed lower thermal diffusivity compared to pure polymers. However, when the compatibilizer was used, the highest value of thermal diffusivity was obtained. Also, cold crystallization with the highest value of enthalpy of fusion was observed for the compatibilized sample, which was revealed by DSC. To our knowledge, this is the first time that the thermal diffusivity of these biodegradable polymer blends is reported.

  7. Photonic polymer-blend structures and method for making

    DOEpatents

    Barnes, Michael D.

    2004-06-29

    The present invention comprises the formation of photonic polymer-blend structures having tunable optical and mechanical properties. The photonic polymer-blend structures comprise monomer units of spherical microparticles of a polymer-blend material wherein the spherical microparticles have surfaces partially merged with one another in a robust inter-particle bond having a tunable inter-particle separation or bond length sequentially attached in a desired and programmable architecture. The photonic polymer-blend structures of the present invention can be linked by several hundred individual particles sequentially linked to form complex three-dimensional structures or highly ordered two-dimensional arrays of 3D columns with 2D spacing.

  8. Reactive extrusion of epsilon-caprolactone polymers and application of poly(lauryl lactam-b-caprolactone) as a compatibilizing agent in blends containing poly(vinyl chloride)

    NASA Astrophysics Data System (ADS)

    Kim, Byong Jun

    In this dissertation, we investigate the continuous polymerization of epsilon-caprolactone (CL) and copolymerization of CL with epsilon-caprolactam (CA), o-lauryl lactam (LA), and styrene (ST) in a modular intermeshing co-rotating twin screw extruder. We consider the variables of temperature profile, screw speed, monomer feed rate, the ratio of monomer to initiator, and feeding order of co-monomers on reactive extrusion of CL polymers. Associated with the reactive extrusion of CL, we also perform the engineering analysis of molecular weight increase and shear-induced molecular weight reduction after polymerization of CL during the reactive extrusion process. Specially designed block copolymers have played a role as compatibilizing agents in the system of immiscible polymer blends. We apply the LA-CL block copolymer (P(LA-b-CL)) produced by reactive extrusion as a compatibilizing agent in immiscible polymer blend systems: (i) poly(vinyl chloride) (PVC)/polyamide 12(PA12), (ii) PVC/polypropylene (PP), and (iii) PVC/maleic anhydride (MA)-modified ethylene-propylene-non-conjugated diene elastomer (MA-EPDM). We investigate the mechanical and thermal properties of (i) PVC/PA12 blend compatibilized with P(LA-b-CL), (ii) PVC/PP blend compatibilized with P(LA-b-CL)/PA12/MA-PP, and (iii) PVC/MA-EPDM blend compatibilized with P(LA-b-CL)/PA12.

  9. Battery separators based on polyphenylquinoxaline polymer blends. Final report

    SciTech Connect

    Angres, I.; Kowalchik, L.; Parkhurst, W.

    1981-04-01

    This document is a final report on battery separators based on polyphenylquinoxaline (PPQ) polymer blends. The report describes the preparation of the polymer blends and their extrusion into membranes, reports a series of quality assurance tests for the membranes, and reports cycle life testing of the new membranes. The test results for the PPQ blend membranes are compared with the results obtained for standard separator membranes. It is concluded that PPQ/Cellulose Acetate is a good candidate material for alkaline battery separators; however, because of cost considerations, it is not competative with similar state-of-the-art materials.

  10. Reaction Kinetics at the Interface between Immiscible Polymers: Competition between Diffusivity and Reactivity

    NASA Astrophysics Data System (ADS)

    Yuan, Guangcui; Wang, Mingji; Han, Charles C.

    2012-02-01

    Reactive blending processes at the interface between deuterated bisphenol-A polycarbonate (dPC) and amorphous polyamide (aPA) bilayer film were characterized by Fourier transform infrared (FTIR) and neutron reflectivity (NR). It was found that the aminolysis occurred during thermal annealing at 160 -- 180 ^oC, inducing simultaneously scission of dPC chains and formation of dPC-aPA copolymer chains. Two or three stages of reaction kinetics as a function of time were probed by FTIR, depending on the competition between chain diffusivity and chemical reactivity for sample annealing at different temperatures. The late stage was controlled by potential barrier arising from previously formed copolymer, and it appeared earlier when annealing at 160 ^oC than that at higher temperatures. A phenomenon of transient interfacial instability which origin was ascribed to the mismatching in mobility of the polymer chains on either side of the interface was observed by NR. The copolymer once formed, remains localized at the interface and inhibits the diffusion of other reactive polymer chains still present in the bulk phase toward the interface.

  11. The use of scanning probe microscopy to characterize polymer blends

    SciTech Connect

    Joseph, T.; Yao, L.; Beatty, C.L.

    1996-12-31

    The use of scanning probe microscopy for the examination of atomic scale phenomena in polymers has been well documented, but the use of scanning probe microscopy to examine submicron scale structures has not been well documented. The purpose of this project was to examine the structure of polymer blends on a submicron scale. Two different systems were studied; a blend of recycled thermoplastics and a blend of ground rubber tire particles in a polystyrene matrix. Topographical images, z modulation plots, internal sensor measurements, and lateral force microscopy images were obtained for both systems. The plots were compared to the structures that we were expected to obtain. A second method of mathematical analysis, fractal dimension measurement, was also performed on the topographical images. Fractal dimension measurement has been correlated to fracture toughness in homopolymers, but the correlation has not been established for polymer blends. Comparison of both methods will be shown.

  12. Controlled release of tocopherols from polymer blend films

    NASA Astrophysics Data System (ADS)

    Obinata, Noe

    Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies

  13. Role of specific interfacial area in controlling properties of immiscible blends of biodegradable polylactide and poly[(butylene succinate)-co-adipate].

    PubMed

    Ojijo, Vincent; Sinha Ray, Suprakas; Sadiku, Rotimi

    2012-12-01

    Binary blends of two biodegradable polymers: polylactide (PLA), which has high modulus and strength but is brittle, and poly[(butylene succinate)-co-adipate] (PBSA), which is flexible and tough, were prepared through batch melt mixing. The PLA/PBSA compositions were 100/0, 90/10, 70/30, 60/40, 50/50, 40/60, 30/70, 10/90, and 0/100. Fourier-transform infrared measurements revealed the absence of any chemical interaction between the two polymers, resulting in a phase-separated morphology as shown by scanning electron microscopy (SEM). SEM micrographs showed that PLA-rich blends had smaller droplet sizes when compared to the PBSA-rich blends, which got smaller with the reduction in PBSA content due to the differences in their melt viscosities. The interfacial area of PBSA droplets per unit volume of the blend reached a maximum in the 70PLA/30PBSA blend. Thermal stability and mechanical properties were not only affected by the composition of the blend, but also by the interfacial area between the two polymers. Through differential scanning calorimetry, it was shown that molten PBSA enhanced crystallization of PLA while the stiff PLA hindered cold crystallization of PBSA. Optimal synergies of properties between the two polymers were found in the 70PLA/30PBSA blend because of the maximum specific interfacial area of the PBSA droplets.

  14. Enhanced Self-Organized Dewetting of Ultrathin Polymer Blend Film for Large-Area Fabrication of SERS Substrate

    PubMed Central

    Zhang, Huanhuan; Xu, Lin; Xu, Yabo; Huang, Gang; Zhao, Xueyu; Lai, Yuqing; Shi, Tongfei

    2016-01-01

    We study the enhanced dewetting of ultrathin Polystyrene (PS)/Poly (methyl methacrylate) (PMMA) blend films in a mixed solution, and reveal the dewetting can act as a simple and effective method to fabricate large-area surface-enhanced Raman scattering (SERS) substrate. A bilayer structure consisting of under PMMA layer and upper PS layer forms due to vertical phase separation of immiscible PS/PMMA during the spin-coating process. The thicker layer of the bilayer structure dominates the dewetting structures of PS/PMMA blend films. The diameter and diameter distribution of droplets, and the average separation spacing between the droplets can be precisely controlled via the change of blend ratio and film thickness. The dewetting structure of 8 nm PS/PMMA (1:1 wt%) blend film is proved to successfully fabricate large-area (3.5 cm × 3.5 cm) universal SERS substrate via deposited a silver layer on the dewetting structure. The SERS substrate shows good SERS-signal reproducibility (RSD < 7.2%) and high enhancement factor (2.5 × 107). The enhanced dewetting of polymer blend films broadens the application of dewetting of polymer films, especially in the nanotechnology, and may open a new approach for the fabrication of large-area SERS substrate to promote the application of SERS substrate in the rapid sensitive detection of trace molecules. PMID:27922062

  15. Enhanced Self-Organized Dewetting of Ultrathin Polymer Blend Film for Large-Area Fabrication of SERS Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Huanhuan; Xu, Lin; Xu, Yabo; Huang, Gang; Zhao, Xueyu; Lai, Yuqing; Shi, Tongfei

    2016-12-01

    We study the enhanced dewetting of ultrathin Polystyrene (PS)/Poly (methyl methacrylate) (PMMA) blend films in a mixed solution, and reveal the dewetting can act as a simple and effective method to fabricate large-area surface-enhanced Raman scattering (SERS) substrate. A bilayer structure consisting of under PMMA layer and upper PS layer forms due to vertical phase separation of immiscible PS/PMMA during the spin-coating process. The thicker layer of the bilayer structure dominates the dewetting structures of PS/PMMA blend films. The diameter and diameter distribution of droplets, and the average separation spacing between the droplets can be precisely controlled via the change of blend ratio and film thickness. The dewetting structure of 8 nm PS/PMMA (1:1 wt%) blend film is proved to successfully fabricate large-area (3.5 cm × 3.5 cm) universal SERS substrate via deposited a silver layer on the dewetting structure. The SERS substrate shows good SERS-signal reproducibility (RSD < 7.2%) and high enhancement factor (2.5 × 107). The enhanced dewetting of polymer blend films broadens the application of dewetting of polymer films, especially in the nanotechnology, and may open a new approach for the fabrication of large-area SERS substrate to promote the application of SERS substrate in the rapid sensitive detection of trace molecules.

  16. Quantifying the effect of polymer blending through molecular modelling of cyanurate polymers.

    PubMed

    Crawford, Alasdair O; Hamerton, Ian; Cavalli, Gabriel; Howlin, Brendan J

    2012-01-01

    Modification of polymer properties by blending is a common practice in the polymer industry. We report here a study of blends of cyanurate polymers by molecular modelling that shows that the final experimentally determined properties can be predicted from first principles modelling to a good degree of accuracy. There is always a compromise between simulation length, accuracy and speed of prediction. A comparison of simulation times shows that 125ps of molecular dynamics simulation at each temperature provides the optimum compromise for models of this size with current technology. This study opens up the possibility of computer aided design of polymer blends with desired physical and mechanical properties.

  17. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, T.

    A polymer blend is disclosed of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  18. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, Terje

    1984-01-01

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  19. Compatibilization of immiscible poly(lactic acid)/poly(ɛ-caprolactone) blend through electron-beam irradiation with the addition of a compatibilizing agent

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Han, Do Hung

    2013-02-01

    The aim of this study was to compatibilize immiscible poly(lactic acid) (PLA)/poly(ɛ-caprolactone) (PCL) blend by using electron-beam radiation method with the addition of a compatibilizing agent. Glycidyl methacrylate (GMA) was chosen as the compatibilizing agent, in the expectation that the GMA plays a role as a monomeric compatibilizer and a reactive agent at the interface between the PLA and the PCL phases. Compatibilization process has been investigated through the melt mixing of the PLA/PCL and the GMA by using a twin-screw extruder and the exposure of the PLA/PCL/GMA mixture to electron-beam radiation at room temperature. The melt mixing process was performed to locate the GMA at the interface, thereby expecting a finer morphology due to the GMA as the monomeric plasticizer. The exposure process was carried out to induce definite interfacial adhesion at the interface through electron-beam initiated cross-copolymerization by the medium of the GMA as the reactive agent. To investigate the results of this compatibilization strategy, the morphological, mechanical, and rheological properties of the blend were analyzed. The morphological study clearly showed the reduced particle size of dispersed PCL domains and significantly improved interfacial adhesion by the electron-beam irradiation with the addition of the GMA. The stress-strain curves of the blends irradiated at less than 20 kGy showed the typical characteristics of ductile materials. The tensile properties of the blend were strongly affected by the dose of irradiation.

  20. Electrospinning polymer blends for biomimetic scaffolds for ACL tissue engineering

    NASA Astrophysics Data System (ADS)

    Garcia, Vanessa Lizeth

    The anterior cruciate ligament (ACL) rupture is one of the most common knee injuries. Current ACL reconstructive strategies consist of using an autograft or an allograft to replace the ligament. However, limitations have led researchers to create tissue engineered grafts, known as scaffolds, through electrospinning. Scaffolds made of natural and synthetic polymer blends have the potential to promote cell adhesion while having strong mechanical properties. However, enzymes found in the knee are known to degrade tissues and affect the healing of intra-articular injuries. Results suggest that the natural polymers used in this study modify the thermal properties and tensile strength of the synthetic polymers when blended. Scanning electron microscopy display bead-free and enzyme biodegradability of the fibers. Raman spectroscopy confirms the presence of the natural and synthetic polymers in the scaffolds while, amino acid analysis present the types of amino acids and their concentrations found in the natural polymers.

  1. Clay platelet partition within polymer blend nanocomposite films by EFTEM.

    PubMed

    Linares, Elisângela M; Rippel, Márcia M; Galembeck, Fernando

    2010-12-01

    Transmission electron microscopy (TEM) is the main technique used to investigate the spatial distribution of clay platelets in polymer nanocomposites, but it has not often been successfully used in polymer blend nanocomposites because the high contrast between polymer phases impairs the observation of clay platelets. This work shows that electron spectral imaging in energy-filtered TEM (EFTEM) in the low-energy-loss spectral crossover region allows the observation of platelets on a clear background. Separate polymer domains are discerned by imaging at different energy losses, above and below the crossover energy, revealing the material morphology. Three blends (natural rubber [NR]/poly(styrene-butyl acrylate) [P(S-BA)], P(S-BA)/poly(vinyl chloride) [PVC], and NR/starch) were studied in this work, showing low contrast between the polymer phases in the 40-60 eV range. In the NR/P(S-BA) and P(S-BA)/PVC blend nanocomposites, the clay platelets accumulate in the P(S-BA) phase, while in the P(S-BA)/PVC nanocomposites, clay is also found at the interfaces. In the NR/starch blend, clay concentrates at the interface, but it also penetrates the two polymer phases. These observations reveal that nanostructured soft materials can display complex morphochemical patterns that are discerned thanks to the ability of EFTEM to produce many contrast patterns for the same sample.

  2. Polymer blends with biodegradable components and reinforcements

    NASA Astrophysics Data System (ADS)

    Sartore, Luciana; Di Landro, Luca

    2014-05-01

    Polymeric blends based on ethylene vinyl acetate rubbers filled with high mol. wt. carboxymethyl cellulose were investigated in view of possible employment as biodegradable materials. The effect of vinyl acetate content and of addition of transesterification agent to increase interaction between EVA and cellulosic components was considered. Blends reinforced with cellulose microfibers in different amounts were also characterized in their mechanical, rheological and thermal behavior.

  3. Homogeneous polymer blend microparticles with a tunable refractive index

    SciTech Connect

    Barnes, M.D.; Kung, C.; Lermer, N.; Fukui, K.; Sumpter, B.G.; Noid, D.W.; Otaigbe, J.U.

    1999-02-01

    We show that homogeneous polymer blend microparticles can be prepared {ital in situ} from droplets of dilute solution of codissolved polymers. Provided that the droplet of solution is small enough ({lt}10 {mu}m) , solvent evaporation is rapid enough to inhibit phase separation. Thus the polymers that are being mixed need not be miscible, which greatly enhances the applicability of the technique. From analysis of two-dimensional Fraunhofer diffraction (angular scattering) patterns, we show that both the real and the imaginary parts of the refractive index can be tuned by adjustment of the relative weight fractions of polymers in solution. {copyright} {ital 1999} {ital Optical Society of America}

  4. Bottlebrush additives drive formation of vesicle chains in polymer blends

    NASA Astrophysics Data System (ADS)

    Mah, Hui Zhen; Afzali, Pantea; Verduzco, Rafeal; Stein, Gila

    2015-03-01

    The effects of bottlebrush polymer additive with poly (styrene-r-methyl methacrylate) side-chains on the thin film morphology of polystyrene (PS) and poly (methyl methacrylate) (PMMA) blends were studied. Results were compared to PS/PMMA blends with diblock copolymer PS-b-PMMA compatibilizer and without any additive. Thin films were spin casted from toluene onto a ``neutral'' silicon surface and then annealed at a fixed temperature of 150ºC for a range of times (up to 85 mins). The morphology of the films was characterized using optical microscopy and atomic force microscopy. In the absence of any additive, the PS/PMMA blend rapidly de-mixes to form macroscale domains, while high loadings of the PS-b-PMMA additive can compatibilize the blend and suppress phase separation. However, the bottlebrush polymer additive drives the formation of well-organized vesicle chains in the PS/PMMA blend films. This morphology is favored by entropic considerations as the bottlebrush polymers are more stable than linear chains at the PS/PMMA interface and the brush like surface attracts.

  5. Exploiting Photo-induced Reactions in Polymer Blends to Create Hierarchically Ordered, Defect-free Materials

    ScienceCinema

    Balazs, Anna [University of Pittsburgh, Pittsburgh, Pennsylvania, United States

    2016-07-12

    Computer simulations reveal how photo-induced chemical reactions can be exploited to create long-range order in binary and ternary polymeric materials. The process is initiated by shining a spatially uniform light over a photosensitive AB binary blend, which undergoes both a reversible chemical reaction and phase separation. We then introduce a well-collimated, higher-intensity light source. Rastering this secondary light over the sample locally increases the reaction rate and causes formation of defect-free, spatially periodic structures. These binary structures resemble either the lamellar or hexagonal phases of microphase-separated di-block copolymers. We measure the regularity of the ordered structures as a function of the relative reaction rates for different values of the rastering speed and determine the optimal conditions for creating defect-free structures in the binary systems. We then add a non-reactive homo-polymer C, which is immiscible with both A and B. We show that this component migrates to regions that are illuminated by the secondary, higher-intensity light, allowing us to effectively write a pattern of C onto the AB film. Rastering over the ternary blend with this collimated light now leads to hierarchically ordered patterns of A, B, and C. The findings point to a facile, non-intrusive process for manufacturing high-quality polymeric devices in a low-cost, efficient manner.

  6. Novel bio-based and biodegradable polymer blends

    NASA Astrophysics Data System (ADS)

    Yang, Shengzhe

    Most plastic materials, including high performance thermoplastics and thermosets are produced entirely from petroleum-based products. The volatility of the natural oil markets and the increasing cost of petroleum have led to a push to reduce the dependence on petroleum products. Together with an increase in environmental awareness, this has promoted the use of alternative, biorenewable, environmentally-friendly products, such as biomass. The growing interest in replacing petroleum-based products by inexpensive, renewable, natural materials is important for sustainable development into the future and will have a significant impact on the polymer industry and the environment. This thesis involved characterization and development of two series of novel bio-based polymer blends, namely polyhydroxyalkanoate (PHA)/polyamide (PA) and poly(lactic acid) (PLA)/soy protein. Blends with different concentrations and compatible microstructures were prepared using twin-screw extruder. For PHA/PA blends, the poor mechanical properties of PHA improved significantly with an excellent combination of strength, stiffness and toughness by adding PA. Furthermore, the effect of blending on the viscoelastic properties has been investigated using small-amplitude oscillatory shear flow experiments as a function of blend composition and angular frequency. The elastic shear modulus (G‧) and complex viscosity of the blends increased significantly with increasing the concentration of PHA. Blending PLA with soy protein aims at reducing production cost, as well as accelerating the biodegradation rate in soil medium. In this work, the mechanical, thermal and morphological properties of the blends were investigated using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests.

  7. Phase behavior of polymer/nanoparticle blends near a substrate

    NASA Astrophysics Data System (ADS)

    McGarrity, E. S.; Frischknecht, A. L.; Mackay, M. E.

    2008-04-01

    We use the recent fluids density functional theory of Tripathi and Chapman [Phys. Rev. Lett. 94, 087801 (2005); J. Chem. Phys. 122, 094506 (2005)] to investigate the phase behavior of athermal polymer/nanoparticle blends near a substrate. The blends are modeled as a mixture of hard spheres and freely jointed hard chains, near a hard wall. There is a first order phase transition present in these blends in which the nanoparticles expel the polymer from the surface to form a monolayer at a certain nanoparticle concentration. The nanoparticle transition density depends on the length of the polymer, the nanoparticle diameter, and the overall bulk density of the system. The phase transition is due to both packing entropy effects related to size asymmetry between the components and to the polymer configurational entropy, justifying the so-called "entropic push" observed in experiments. In addition, a layered state is found at higher densities which resembles that in colloidal crystals, in which the polymer and nanoparticles form alternating discrete layers. We show that this laminar state has nearly the same free energy as the homogeneously mixed fluid in the bulk and is nucleated by the surface.

  8. Genistein Modified Polymer Blends for Hemodialysis Membranes

    NASA Astrophysics Data System (ADS)

    Chang, Teng; Kyu, Thein; Define, Linda; Alexander, Thomas

    2012-02-01

    A soybean-derived phytochemical called genistein was used as a modifying agent to polyether sulfone/polyvinyl pyrrolidone (PES/PVP) blends to produce multi-functional hemodialysis membranes. With the aid of phase diagrams of PES/PVP/genistein blends, asymmetric porous membranes were fabricated by coagulating in non-solvent. Both unmodified and genistein modified PES/PVP membranes were shown to be non-cytotoxic to the blood cells. Unmodified PES/PVP membranes were found to reduce reactive oxygen species (ROS) levels, whereas the genistein modified membranes exhibited suppression for ˜60% of the ROS levels. Also, the genistein modified membranes revealed significant suppression of pro-inflammatory cytokines: IL-1β, IL-6, and TNF-α. Moreover, addition of PVP to PES showed the reduced trend of platelet adhesion and then leveled off. However, the modified membranes exhibited suppression of platelet adhesion at low genistein loading, but beyond 15 wt%, the platelet adhesion level rised up.

  9. Thermoforming process using modified polymer blend

    SciTech Connect

    Davison, S.

    1984-12-18

    An improved thermoforming process comprises the use of crystalline polymer sheets prepared by the peroxide reacting of the mixture of a poly(alpha olefin) selected from polypropylene and polybutylene plus a polyethylene.

  10. Predicting morphologies of solution processed polymer:fullerene blends.

    PubMed

    Kouijzer, Sandra; Michels, Jasper J; van den Berg, Mauricio; Gevaerts, Veronique S; Turbiez, Mathieu; Wienk, Martijn M; Janssen, René A J

    2013-08-14

    The performance of solution processed polymer:fullerene thin film photovoltaic cells is largely determined by the nanoscopic and mesoscopic morphology of these blends that is formed during the drying of the layer. Although blend morphologies have been studied in detail using a variety of microscopic, spectroscopic, and scattering techniques and a large degree of control has been obtained, the current understanding of the processes involved is limited. Hence, predicting the optimized processing conditions and the corresponding device performance remains a challenge. We present an experimental and modeling study on blends of a small band gap diketopyrrolopyrrole-quinquethiophene alternating copolymer (PDPP5T) and [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM) cast from chloroform solution. The model uses the homogeneous Flory-Huggins free energy of the multicomponent blend and accounts for interfacial interactions between (locally) separated phases, based on physical properties of the polymer, fullerene, and solvent. We show that the spinodal liquid-liquid demixing that occurs during drying is responsible for the observed morphologies. The model predicts an increasing feature size and decreasing fullerene concentration in the polymer matrix with increasing drying time in accordance with experimental observations and device performance. The results represent a first step toward a predictive model for morphology formation.

  11. Sensitivity of polymer blends to synchrotron radiation. Technical note

    SciTech Connect

    Jubinsky, J.A.; Groele, R.J.; Rodriquez, F.; Namaste, Y.M.; Obendorf, S.K.

    1986-09-26

    The sensitivity of poly(methylmethacrylate), PMMA, to x rays is enhanced by the addition of poly(epichlorohydrin), CO rubber. The two polymers appear to be miscible over a wide concentration range. Films with 20 to 50% CO in PMMA require only 1/2 to 1/4 the exposure dose of synchrotron radiation to produce an equivalent pattern in PMMA alone. The sensitivity is confirmed by measurements of molecular weight of blends irradiated by gamma rays or electrons, a well as x rays. Dissolution behavior of the blends also is similar to that for PMMA.

  12. Polymer blend lithography for metal films: large-area patterning with over 1 billion holes/inch2

    PubMed Central

    Huang, Cheng; Förste, Alexander; Schimmel, Thomas

    2015-01-01

    Summary Polymer blend lithography (PBL) is a spin-coating-based technique that makes use of the purely lateral phase separation between two immiscible polymers to fabricate large area nanoscale patterns. In our earlier work (Huang et al. 2012), PBL was demonstrated for the fabrication of patterned self-assembled monolayers. Here, we report a new method based on the technique of polymer blend lithography that allows for the fabrication of metal island arrays or perforated metal films on the nanometer scale, the metal PBL. As the polymer blend system in this work, a mixture of polystyrene (PS) and poly(methyl methacrylate) (PMMA), dissolved in methyl ethyl ketone (MEK) is used. This system forms a purely lateral structure on the substrate at controlled humidity, which means that PS droplets are formed in a PMMA matrix, whereby both phases have direct contact both to the substrate and to the air interface. Therefore, a subsequent selective dissolution of either the PS or PMMA component leaves behind a nanostructured film which can be used as a lithographic mask. We use this lithographic mask for the fabrication of metal patterns by thermal evaporation of the metal, followed by a lift-off process. As a consequence, the resulting metal nanostructure is an exact replica of the pattern of the selectively removed polymer (either a perforated metal film or metal islands). The minimum diameter of these holes or metal islands demonstrated here is about 50 nm. Au, Pd, Cu, Cr and Al templates were fabricated in this work by metal PBL. The wavelength-selective optical transmission spectra due to the localized surface plasmonic effect of the holes in perforated Al films were investigated and compared to the respective hole diameter histograms. PMID:26171297

  13. Structure evolution in layers of polymer blend nanoparticles.

    PubMed

    Raczkowska, Joanna; Montenegro, Rivelino; Budkowski, Andrzej; Landfester, Katharina; Bernasik, Andrzej; Rysz, Jakub; Czuba, Paweł

    2007-06-19

    The early stages of phase evolution, not available for nanometer polymer blend films spin-cast from solutions of incompatible mixtures, have been examined for films prepared from nanoparticles of deuterated polystyrene/ poly(methyl methacrylate) blends (1:1 mass fraction of dPS/PMMA) with PS-PMMA diblock copolymer additives. The initial phase arrangement, confined to the size of nanoparticles, has provided the homogeneity of the initial film composition. The early stages of structure formation, promoted by annealing and traced with atomic and lateral force microscopy (AFM, LFM) as well as secondary ion mass spectroscopy (SIMS), resulted in bilayers, observed commonly for as-prepared solvent-cast blends. The initiated capillary instability of the upper dPS-rich layer depended on copolymer additives, which enhanced the lateral structures pinning the dewetting process.

  14. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

    DOEpatents

    Skotheim, Terje

    1986-01-01

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  15. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

    DOEpatents

    Skotheim, T.

    1984-09-28

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  16. Analysis of thermoplastic polyimide + polymer liquid crystal blends

    NASA Astrophysics Data System (ADS)

    Gopalanarayanan, Bhaskar

    Thermoplastic polyimides (TPIs) exhibit high glass transition temperatures (Tsbgs), which make them useful in high performance applications. Amorphous and semicrystalline TPIs show sub-Tsbg relaxations, which can aid in improving strength characteristics through energy absorption. The alpha relaxation of both types of TPIs indicates a cooperative nature. The semicrystalline TPI shows thermo-irreversible cold crystallization phenomenon. The polymer liquid crystal (PLC) used in the blends is thermotropic and with longitudinal molecular structure. The small heat capacity change (Delta Csb{p}) associated with the glass transition indicates the PLC to be rigid rod in nature. The PLC shows a small endotherm associated with the melting. The addition of PLC to the semicrystalline TPI does not significantly affect the Tsbg or the melting point (Tsbm). The cold crystallization temperature (Tsbc) increases with the addition of the PLC, indicating channeling phenomenon. The addition of PLC also causes a negative deviation of the Delta Csb{p}, which is another evidence for channeling. The TPI, PLC and their blends show high thermal stability. The semicrystalline TPI absorbs moisture; this effect decreases with the addition of the PLC. The absorbed moisture does not show any effect on the degradation. The addition of PLC beyond 30 wt.% does not result in an improvement of properties. The amorphous TPI + PLC blends also show the negative deviation of Delta Csb{p} from linearity with composition. The addition of PLC causes a decrease in the thermal conductivity in the transverse direction to the PLC orientation. The thermomechanical analysis indicates isotropic expansivity for the amorphous TPI and a small anisotropy for the semicrystalline TPI. The PLC shows large anisotropy in expansivity. Even 5 wt.% concentration of PLC in the blend induces considerable anisotropy in the expansivity. Thus, blends show controllable expansivity through PLC concentration. Amorphous TPI + PLC

  17. Significantly Increasing the Ductility of High Performance Polymer Semiconductors through Polymer Blending.

    PubMed

    Scott, Joshua I; Xue, Xiao; Wang, Ming; Kline, R Joseph; Hoffman, Benjamin C; Dougherty, Daniel; Zhou, Chuanzhen; Bazan, Guillermo; O'Connor, Brendan T

    2016-06-08

    Polymer semiconductors based on donor-acceptor monomers have recently resulted in significant gains in field effect mobility in organic thin film transistors (OTFTs). These polymers incorporate fused aromatic rings and have been designed to have stiff planar backbones, resulting in strong intermolecular interactions, which subsequently result in stiff and brittle films. The complex synthesis typically required for these materials may also result in increased production costs. Thus, the development of methods to improve mechanical plasticity while lowering material consumption during fabrication will significantly improve opportunities for adoption in flexible and stretchable electronics. To achieve these goals, we consider blending a brittle donor-acceptor polymer, poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (PCDTPT), with ductile poly(3-hexylthiophene). We found that the ductility of the blend films is significantly improved compared to that of neat PCDTPT films, and when the blend film is employed in an OTFT, the performance is largely maintained. The ability to maintain charge transport character is due to vertical segregation within the blend, while the improved ductility is due to intermixing of the polymers throughout the film thickness. Importantly, the application of large strains to the ductile films is shown to orient both polymers, which further increases charge carrier mobility. These results highlight a processing approach to achieve high performance polymer OTFTs that are electrically and mechanically optimized.

  18. The influence of the amorphous polymer on conductivity, morphologies and thermal properties of polyether-based blends with addition of inorganic salt

    NASA Astrophysics Data System (ADS)

    Chan, C. H.; Sim, L. H.; Kammer, H. W.; Tan, W.

    2012-06-01

    Thermodynamic control of the dispersion of lithium (Li) salt in different phases of semicrystalline/amorphous polymer blends is elucidated in this study. Solid polymer electrolytes of poly(ethylene oxide) (PEO), epoxidized natural rubber (ENR), random copolymer of poly(acrylate) (PAc) and as well as polymer blends of PEO with ENR and PAc doped with various concentrations of Li salt were studied. The salt concentrations (CLi) of solid polymer electrolytes vary between CLi = 0.02 and 0.15. The influence of the ENR or PAc on the properties of PEO after addition of Li salt is discussed. Blends of PEO/ENR and PEO/PAc are immiscible by elucidation of the glass transition temperature (Tg) as well as the morphological analyses. PEO, ENR and PAc possess oxygen in their respective chemical structures, which may be able to coordinate with the Li salt added. Non uniformity of Li salt concentration in different phases of the blends is highlighted for both systems. The conductivity of PEO/ENR and PEO/PAc blends doped with Li salt is primarily governed by PEO. The results for Tg suggest that higher solubility of Li salt in PEO as compared to ENR in the former case and restricted ion transport in the glassy PAc (with Tg≈30°C after addition of Li salt in the latter system. These may be the attributing factors for the enhancement of conductivity of the doped-PEO/ENR blends as compared to that of the doped-PEO/PAc blends. This suggests that PEO exhibits greater extent of complexation with LiClO4 as compared to that of the ENR and PAc as supported by Fourier-transform infra-red (FTIR) studies.

  19. Conductivity Studies in PVA-PEO-PEG Blended Polymer Films Complexed with Silver Salt

    NASA Astrophysics Data System (ADS)

    Joge, Prajakta; Kanchan, D. K.; Sharma, Poonam; Gondaliya, Nirali

    2011-07-01

    The PVA-PEO blended polymer films complexed with silver nitrate salt and PEG plasticizer were prepared by solution cast technique. The prepared polymer films are characterized by XRD, DSC and impedance spectroscopy. The electrical properties of the blended plasticized polymer films have been discussed.

  20. Interfacial Tension of Immiscible Polymer Blends: Temperature and Molecular Weight Dependence.

    DTIC Science & Technology

    1988-02-02

    G . L ., Jr.; Gaines, G . L . III. J. Colloid Interface Sci. 1978, 63, 394. 11. Girifalco , L . A .; Good , R . J. j. Phys. Chem. 1957...several empirical theories which relate interfacial tension to the pure component surface tensions. 11,12 A number of thermodynamic theories13-20 have...Huggins expression for the free energy of mixing, predicts a magnitude and temperature dependence of interfacial tension which are

  1. Tuning particle biodegradation through polymer-peptide blend composition.

    PubMed

    Gunawan, Sylvia T; Kempe, Kristian; Such, Georgina K; Cui, Jiwei; Liang, Kang; Richardson, Joseph J; Johnston, Angus P R; Caruso, Frank

    2014-12-08

    We report the preparation of polymer-peptide blend replica particles via the mesoporous silica (MS) templated assembly of poly(ethylene glycol)-block-poly(2-diisopropylaminoethyl methacrylate-co-2-(2-(2-(prop-2-ynyloxy)ethoxy)ethoxy)ethyl methacrylate) (PEG45-b-P(DPA55-co-PgTEGMA4)) and poly(l-histidine) (PHis). PEG45-b-P(DPA55-co-PgTEGMA4) was synthesized by atom transfer radical polymerization (ATRP), and was coinfiltrated with PHis into poly(methacrylic acid) (PMA)-coated MS particles assembled from different peptide-to-polymer ratios (1:1, 1:5, 1:10, or 1:15). Subsequent removal of the sacrificial templates and PMA resulted in monodisperse, colloidally stable, noncovalently cross-linked polymer-peptide blend replica particles that were stabilized by a combination of hydrophobic interactions between the PDPA and the PHis, hydrogen bonding between the PEG and PHis backbone, and π-π stacking of the imidazole rings of PHis side chains at physiological pH (pH ∼ 7.4). The synergistic charge-switchable properties of PDPA and PHis, and the enzymatic degradability of PHis, make these particles responsive to pH and enzymes. In vitro studies, in simulated endosomal conditions and inside cells, demonstrated that particle degradation kinetics could be engineered (from 2 to 8 h inside dendritic cells) based on simple adjustment of the peptide-to-polymer ratio used.

  2. Controlling the morphology of polymer blends using periodic irradiation

    NASA Astrophysics Data System (ADS)

    Tran-Cong-Miyata, Qui; Nishigami, Shinsuke; Ito, Tetsuo; Komatsu, Satonori; Norisuye, Tomohisa

    2004-07-01

    Morphology is the decisive factor controlling practical properties such as impact strength or transparency in multiphase polymeric materials. The co-continuous structure formed by polymers has been of great interest to material scientists because of their superiority over those with random morphology. Although a number of efforts-including forcibly freezing the spinodal structure of polymer blends-have been made to produce materials with co-continuous structures, an efficient method for controlling their regularity is still lacking. Here, we demonstrate a novel method using periodic photo-crosslinking to control the length-scale distribution of the spinodal structure in binary polymer blends. It was found that the period distribution of the resulting co-continuous structure became significantly narrow under this periodic forcing. Also, there exists a particular irradiation frequency at which the periodic structure exhibits a minimum, indicating the existence of an ordering process driven by the external modulation frequency. Our findings reveal an easy way to produce polymer materials that is not only useful for optical applications, but also promising for biological separation, such as hemodialysis.

  3. Blended polymer materials extractable with supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Cai, Mei

    Supercritical carbon dioxide is drawing more and more attention because of its unique solvent properties along with being environmentally friendly. Historically most of the commercial interests of supercritical carbon dioxide extraction are in the food industry, pharmaceutical industry, environmental preservation and polymer processing. Recently attention has shifted from the extraction of relatively simple molecules to more complex systems with a much broader range of physical and chemical transformations. However the available data show that a lot of commercially valuable substances are not soluble in supercritical carbon dioxide due to their polar structures. This fact really limits the application of SCF extraction technology to much broader industrial applications. Therefore, the study of a polymer's solubility in a given supercritical fluid and its thermodynamic behavior becomes one of the most important research topics. The major objective of this dissertation is to develop a convenient and economic way to enhance the polymer's solubility in supercritical carbon dioxide. Further objective is to innovate a new process of making metal casting parts with blended polymer materials developed in this study. The key technique developed in this study to change a polymer's solubility in SCF CO2 is to thermally blend a commercially available and CO2 non-soluble polymer material with a low molecular weight CO2 soluble organic chemical that acts as a co-solute. The mixture yields a plastic material that can be completely solubilized in SCF CO2 over a range of temperatures and pressures. It also exhibits a variety of physical properties (strength, hardness, viscosity, etc.) depending on variations in the mixture ratio. The three organic chemicals investigated as CO2 soluble materials are diphenyl carbonate, naphthalene, and benzophenone. Two commercial polymers, polyethylene glycol and polystyrene, have been investigated as CO2 non-soluble materials. The chemical

  4. Novel polymer blends with thermoplastic starch

    NASA Astrophysics Data System (ADS)

    Taghizadeh, Ata

    A new class of polymers known as "bioplastics" has emerged and is expanding rapidly. This class consists of polymers that are either bio-based or biodegradable, or both. Among these, polysaccharides, namely starch, are of great interest for several reasons. By gelatinizing starch via plasticizers, it can be processed in the same way as thermoplastic polymers with conventional processing equipment. Hence, these bio-based and biodegradable plastics, with their low source and refinery costs, as well as relatively easy processability, have made them ideal candidates for incorporation into various current plastic products. Four different plasticizers have been chosen here for gelatinization of thermoplastic starch (TPS): glycerol, sorbitol, diglycerol and polyglycerol, with the latter two being used for the first time in such a process. Two methodological categories are used. The first involves a calorimetric method (Differential Scanning Calorimetry) as well as optical microscopy; these are "static" methods where no shear is applied A wide range of starch/water/plasticizer compositions were prepared to explore the gelatinization regime for each plasticizer. The onset and conclusion gelatinization temperatures for sorbitol and glycerol were found to be in the same vicinity, while diglycerol and polyglycerol showed significantly higher transition temperatures. The higher molecular weight and viscosity of polyglycerol allow this transition to occur at an even higher temperature than with diglycerol. This is due to the increase in molecular weight and viscosity of the two new plasticizers, as well as their significant decrease in water solubility. It is demonstrated that the water/plasticizer ratio has a pronounced effect on gelatinization temperatures. When plasticizer content was held constant and water content was increased, it was found that the gelatinization temperature decreased for all the plasticizers. Meanwhile, when the water content was held constant and the

  5. Miscibility Studies on Polymer Blends Modified with Phytochemicals

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Neelakandan; Kyu, Thein

    2009-03-01

    The miscibility studies related to an amorphous poly(amide)/poly(vinyl pyrrolidone) [PA/PVP] blend with a crystalline phytochemical called ``Mangiferin'' is presented. Phytochemicals are plant derived chemicals which intrinsically possess multiple salubrious properties that are associated with prevention of diseases such as cancer, diabetes, cardiovascular disease, and hypertension. Incorporation of phytochemicals into polymers has shown to have very promising applications in wound healing, drug delivery, etc. The morphology of these materials is crucial to applications like hemodialysis, which is governed by thermodynamics and kinetics of the phase separation process. Hence, miscibility studies of PA/PVP blends with and without mangiferin have been carried out using dimethyl sulfoxide as a common solvent. Differential scanning calorimetry studies revealed that the binary PA/PVP blends were completely miscible at all compositions. However, the addition of mangiferin has led to liquid-liquid phase separation and liquid-solid phase transition in a composition dependent manner. Fourier transformed infrared spectroscopy was undertaken to determine specific interaction between the polymer constituents and the role of possible hydrogen bonding among three constituents will be discussed.

  6. Polymer blends made of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and epoxidized natural rubber: Thermal and mechanical response

    NASA Astrophysics Data System (ADS)

    Salim, Yoga Sugama; Han, Chan Chin; Kammer, Hans-Werner; Kumar, Sudesh; Neon, Gan Seng

    2015-08-01

    The ever-increasing demand of biodegradable over conventional polymers places microbial polyhydroxyalkanoates (PHA) as an ideal choice of research material for specific applications. In this study, polymer blends made of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx) and epoxidized natural rubber (ENR) were prepared using solution casting technique. The influence of ENR on thermal, morphological and mechanical properties of P(3HB-co-3HHx) was investigated. There are two glass transition (Tg) temperatures observed using differential scanning calorimeter. This indicates that P(3HB-co-3HHx) and ENR are immiscible at macroscopic level. Although the Tg of P(3HB-co-3HHx) is seen to shift toward ENR in the least manner, infrared analysis suggests that the crystal structure of P(3HB-co-3HHx) retains its conformational structure. In terms of morphology, ENR exists as droplets in P(3HB-co-3HHx)-rich phase, e.g. at ENR weight fraction (wENR) of 0.3. In dynamic mechanical analysis, all blend compositions exhibit solid-like behavior, with storage moduli larger than loss moduli, across the frequency sweep at room temperature.

  7. A novel reactive processing technique: using telechelic polymers to reactively compatibilize polymer blends

    SciTech Connect

    Ashcraft, Earl C; Ji, Haining; Mays, Jimmy; Dadmun, Mark D

    2009-01-01

    Difunctional reactive polymers, telechelics, were used to reactively form multiblock copolymers in situ when melt-blended with a blend of polystyrene and polyisoprene. To quantify the ability of the copolymer to compatibilize the blends, the time evolution of the domain size upon annealing was analyzed by SEM. It was found that the most effective parameter to quantify the ability of the copolymer to inhibit droplet coalescence is Kreltstable, the relative coarsening constant multiplied by the stabilization time. These results indicate that intermediate-molecular-weight telechelic pairs of both highly reactive Anhydride-PS-Anhydride/NH2-PI-NH2 and slower reacting Epoxy-PS-Epoxy/COOH-PI-COOH both effectively suppress coalescence, with the optimal molecular weight being slightly above the critical molecular weight of the homopolymer,Mc. The effects of telechelic loading were also investigated, where the optimal loading concentration for this system was 0.5 wt %, as higher concentrations exhibited a plasticizing effect due to the presence of unreacted low-molecular-weight telechelics present in the blend. A determination of the interfacial coverage of the copolymer shows that a conversion of 1.5-3.0% was required for 20% surface coverage at 5.0 wt % telechelic loading, indicating a large excess of telechelics in this system. At the optimal loading level of 0.5 wt %, a conversion of 15% was required for 20% surface coverage. The results of these experiments provide a clear understanding of the role of telechelic loading and molecular weight on its ability to reactively form interfacial modifiers in phase-separated polymer blends and provide guidelines for the development of similar reactive processing schemes that can use telechelic polymers to reactively compatibilize a broad range of polymer blends.

  8. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    SciTech Connect

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-23

    Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation-{pi}' interactions during melt-mixing leading to percolative 'network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation-{pi}' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

  9. Capillary Condensation in Polymer Blends: an Analysis of Phase Transitions

    NASA Astrophysics Data System (ADS)

    Ilie, Carolina C.; Jira, Nicholas C.; Evans, Ian R.; Cohen, Matthew; D'Rozario, Julia R.; Romano, Marie T.; Sabirianov, Ildar

    We explore herein the capillary condensation for various geometries. Capillary condensation is studied in the presence of van der Waals forces. We derive the grand free energy, and we analyze the phase transitions, the absorption isotherms and the triple point. Phase transitions between full, empty and two films are investigated and the shape of the liquid is calculated. We also analyze an important application of wetting phenomena and capillary condensation in binary polymer blends and investigate the type of wetting transitions presented and the phase diagram. SUNY Oswego SCAC Grant, NSF Noyce Grant.

  10. Development and characterization of porous polypyrrole-polylactic acid electroactive polymer blends

    NASA Astrophysics Data System (ADS)

    Chan, Christine; Chan, Ellen; Naguib, Hani E.

    2009-03-01

    Conducting polymers have sparked much research interest due to their unique ability to be electrically stimulated. However, these polymers are very brittle and have poor mechanical properties. In order to improve upon its structural integrity, it can be blended with other host polymers that have better mechanical properties. These blended composites would then possess the benefits of conductive properties while having sufficient mechanical properties to be more suitable for practical applications. Polypyrrole-polylactic acid blends were processed using chemical oxidative polymerization and compression molding, followed by gas foaming and saturation techniques to create porous structures. Characterization of these porous blends included its physical, thermal, and mechanical properties.

  11. Characterization of Polymer Blends: Optical Microscopy (*Polarized, Interference and Phase Contrast Microscopy*) and Confocal Microscopy

    SciTech Connect

    Ramanathan, Nathan Muruganathan; Darling, Seth B.

    2015-01-01

    Chapter 15 surveys the characterization of macro, micro and meso morphologies of polymer blends by optical microscopy. Confocal Microscopy offers the ability to view the three dimensional morphology of polymer blends, popular in characterization of biological systems. Confocal microscopy uses point illumination and a spatial pinhole to eliminate out-of focus light in samples that are thicker than the focal plane.

  12. Controlling protein release from scaffolds using polymer blends and composites.

    PubMed

    Ginty, Patrick J; Barry, John J A; White, Lisa J; Howdle, Steve M; Shakesheff, Kevin M

    2008-01-01

    We report the development of three protein loaded polymer blend and composite materials that modify the release kinetics of the protein from poly(dl-lactic acid) (P(dl)LA) scaffolds. P(dl)LA has been combined with either poly(ethylene glycol) (PEG), poly(caprolactone) (PCL) microparticles or calcium alginate fibres using supercritical CO(2) (scCO(2)) processing to form single and dual protein release scaffolds. P(dl)LA was blended with the hydrophilic polymer PEG using scCO(2) to increase the water uptake of the resultant scaffold and modify the release kinetics of an encapsulated protein. This was demonstrated by the more rapid release of the protein when compared to the release rate from P(dl)LA only scaffolds. For the P(dl)LA/alginate scaffolds, the protein loaded alginate fibres were processed into porous protein loaded P(dl)LA scaffolds using scCO(2) to produce dual release kinetics from the scaffolds. Protein release from the hydrophilic alginate fibres was more rapid in the initial stages, complementing the slower release from the slower degrading P(dl)LA scaffolds. In contrast, when protein loaded PCL particles were loaded into P(dl)LA scaffolds, the rate of protein release was retarded from the slow degrading PCL phase.

  13. A new class of bio-heat resisted polymer blend.

    NASA Astrophysics Data System (ADS)

    Pack, Seongchan; Kashiwagi, Takashi; Koga, Tadanori; Rafailovich, Miriam

    2009-03-01

    Increasing in oil prices and environmental concerns is a driving force to seek out alternative materials. A completely biodegradable starch is a candidate for the alternative materials. Since the starch is brittle, it must be mixed with other polymers. In order to make a thermoplastic starch (TPS), we need a bio-compatiblizer to increase a degree of compatibilization. The biocompatibilzer can be a small molecules or nanoparticles with the small molecules, which leads to improved material properties. In order to demonstrate a possible biocompatibilzer, we first developed a corn-based starch impregnated with non-halogenated flame retardant formulations. The starch was blended with Ecoflex, a biodegradable polymer. Using SAXS and USAXS we characterized structures of the compounds with different amount of Ecoflex by weight. Furthermore, the addition of 5% nanoparticles in the compounds increased the Young's Modulus and impact toughness significantly. The compounds also did flame test. It is indicated that the compound with the addition of the nanopaticles would pass with a UL-94V0 rating. Therefore, the procedure for producing these TPS compounds can be applied to any biodegradable polymers, manufacturing a new bio-heat resisted compound.

  14. Polaron pair mediated triplet generation in polymer/fullerene blends

    PubMed Central

    Dimitrov, Stoichko D.; Wheeler, Scot; Niedzialek, Dorota; Schroeder, Bob C.; Utzat, Hendrik; Frost, Jarvist M.; Yao, Jizhong; Gillett, Alexander; Tuladhar, Pabitra S.; McCulloch, Iain; Nelson, Jenny; Durrant, James R.

    2015-01-01

    Electron spin is a key consideration for the function of organic semiconductors in light-emitting diodes and solar cells, as well as spintronic applications relying on organic magnetoresistance. A mechanism for triplet excited state generation in such systems is by recombination of electron-hole pairs. However, the exact charge recombination mechanism, whether geminate or nongeminate and whether it involves spin-state mixing is not well understood. In this work, the dynamics of free charge separation competing with recombination to polymer triplet states is studied in two closely related polymer-fullerene blends with differing polymer fluorination and photovoltaic performance. Using time-resolved laser spectroscopic techniques and quantum chemical calculations, we show that lower charge separation in the fluorinated system is associated with the formation of bound electron-hole pairs, which undergo spin-state mixing on the nanosecond timescale and subsequent geminate recombination to triplet excitons. We find that these bound electron-hole pairs can be dissociated by electric fields. PMID:25735188

  15. Analytic PRISM theory of structurally asymmetric polymer blends and copolymers

    SciTech Connect

    Schweizer, K.S. )

    1993-10-25

    Analytic PRISM theory with the new molecular closures is applied to determine the effective chi-parameters and spinodal instability curves for structurally asymmetric polymer alloys. Compressibility effects are found to be very important, and the use of a literal incompressible RPA-like approximation is shown to incur qualitative errors in most cases. A rich and nonadditive dependence of phase transition temperatures and apparent SANS chi-parameters on backbone stiffness asymmetry, attractive interaction potential asymmetry, and thermodynamic variables is found for binary homopolymer blends. A novel strategy for designing miscible mixtures based on a cancellation, or compensation, of the relevant asymmetries is identified. The influence of chain stiffness asymmetry in blends characterized by specific interactions is also studied. Generalization of the analytic PRISM theory to mixtures of random copolymers and periodic block copolymer melts is presented. All the rich behavior predicted for phase-separating homopolymer mixtures is again found for these systems, plus additional non mean field effects associated with random copolymer composition and block architecture. The theory is applied semiquantitatively to interpret recent experiments on polyolefin blends, diblock copolymers, and random copolymer alloys. Theoretical predictions are made which qualitatively account for recent experimental observations of a strong influence of stiffness asymmetry on phase separation temperatures, and the breakdown of the mean field random copolymer approach. Anomalous behavior is also predicted for deuterated mixtures due to an interference between the consequences of stiffness asymmetry and enthalipic interactions. The physical mechanism for the many non-Flory-Huggins effects predicted by the compressible PRISM theory is local, scalar density correlations, which appears to be different than the nematic fluctuation mechanism suggested by recent field theoretic work.

  16. FTIR studies of PVC/PMMA blend based polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Ramesh, S.; Leen, Koay Hang; Kumutha, K.; Arof, A. K.

    2007-04-01

    The polymer electrolytes composing of the blend of polyvinyl chloride-polymethyl methacrylate (PVC/PMMA) with lithium triflate (LiCF 3SO 3) as salt, ethylene carbonate (EC) and dibutyl phthalate (DBP) as plasticizers and silica (SiO 2) as the composite filler were prepared. FTIR studies confirm the complexation between PVC/PMMA blends. The C sbnd Cl stretching mode at 834 cm -1 for pure PVC is shifted to 847 cm -1 in PVC-PMMA-LiCF 3SO 3 system. This suggests that there is interaction between Cl in PVC with Li + ion from LiCF 3SO 3. The band due to sbnd OCH 3 at 1150 cm -1 for PVC-PMMA blend is shifted to 1168 cm -1 in PVC-PMMA-LiCF 3SO 3 system. This shift is expected to be due to the interaction between Li + ion and the oxygen atom in PMMA. The symmetric vibration band and the asymmetric vibration band of LiCF 3SO 3 at 1033 and 1256 cm -1 shifted to 1075 and 1286 cm -1 in the DBP-EC plasticized PVC-PMMA-LiCF 3SO 3 complexes. The interaction between Li + ions and SiO 2 will lead to an increase in the number of free plasticizers (which does not interact with Li + ions). When the silica content increases from 2% to 5%, the intensity of the peak at 896 cm -1 (due to the ring breathing vibration of free EC) increases in PVC-PMMA-LiCF 3SO 3-DBP-EC system.

  17. Electrical Properties of Polymer/Carbon Nanotube Blends

    NASA Astrophysics Data System (ADS)

    Salgado-Delgado, R.; Olarte-Paredes, A.; Vargas-Galarza, Z.; García-Hernández, E.; Salgado-Delgado, A. M.; Rubio-Rosas, E.; Campos-Álvarez, J.; Castaño, V. M.

    2016-10-01

    Electrical and morphological properties of a novel composite, consisting of polypyrrole (PPy)/carbon black (CB)/carbon nanotubes (CNT), within a polyethylene (PE) matrix, are reported. The electrical properties were studied according to the type of filler (i.e. PPy, CB or CNT). The resistivity, analyzed by the Van der Pauw method, shows values in the range of (1E+15 for PE to 1.07E-01 for M15) Ω cm. The filler is distributed as one phase within the blended matrix and/or at the interface between the polymers, thus producing a highly homogeneous material. The morphology and degree of dispersion of the PPy/CB/CNTs in the PE matrix at different concentrations were investigated by scanning electron microscopy.

  18. Optical characterization of phase transitions in pure polymers and blends

    SciTech Connect

    Mannella, Gianluca A.; Brucato, Valerio; La Carrubba, Vincenzo

    2015-12-17

    To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample. Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.

  19. Optical characterization of phase transitions in pure polymers and blends

    NASA Astrophysics Data System (ADS)

    Mannella, Gianluca A.; Brucato, Valerio; La Carrubba, Vincenzo

    2015-12-01

    To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample. Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.

  20. Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH4SCN

    NASA Astrophysics Data System (ADS)

    Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Genova, F. Kingslin Mary; Umamaheswari, R.

    2016-05-01

    Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10-3 S cm-1 for 20 mol % NH4SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.

  1. Polylactic Acid-Based Polymer Blends for Durable Applications

    NASA Astrophysics Data System (ADS)

    Finniss, Adam

    There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of the material as a durable item: it has low ductility and impact strength in bulk applications, along with poor stability in the face of heat, humidity or liquid media. To combat these deficiencies, a number of techniques were investigated. Samples were annealed to create crystalline domains that would improve mechanical properties and reduce diffusion, blended with graphene to create barriers to diffusion throughout the material, or compounded with a polycarbonate (PC) polymer phase to protect the PLA phase and to enhance the mechanical properties of the blend. If a material containing biologically sourced components with good mechanical properties can be created, it would be desirable for durable uses such as electronics components or as an automotive grade resin. Crystallization experiments were carried out in a differential scanning calorimeter to determine the effects of heat treatment and additives on the rather slow crystallization kinetics of PLA polymer. It was determined that the blending in of the PC phase did not significantly alter the kinetics or mechanism of crystal growth. The addition of graphene to any PC/PLA formulation served as a nucleating agent which speeded up the crystallization kinetics markedly, in some cases by several orders of magnitude. Results obtained from these experiments were internally consistent

  2. Tailoring nanoscale morphology of polymer: Fullerene blends using electrostatic field

    DOE PAGES

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; ...

    2016-12-05

    In this paper, to tailor the nanoscale phase separation in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to untreated sample (control); wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions – horizontal (H), tilted (T) and vertical (V) – relative to the plane of the substrate. Surface and bulk characterizations of field-treated BHJs affirm that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. E-fieldmore » treatment yields thin films with large P3HT- and PCBM-rich domains acting as continuous pathways for efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10-4 ± 1.6 × 10-4 cm2 V-1 s-1 (117% higher than the control), and (2) power conversion efficient (PCE) of conventional and inverted OPVs recording 2.58 ± 0.02% and 4.1 ± 0.4%. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.« less

  3. Controlling Au Nanorod Dispersion in Thin Film Polymer Blends

    NASA Astrophysics Data System (ADS)

    Hore, Michael J. A.; Composto, Russell J.

    2012-02-01

    Dispersion of Au nanorods (Au NRs) in polymer thin films is studied using a combination of experimental and theoretical techniques. Here, we incorporate small volume fractions of polystyrene-functionalized Au NRs (φrod 0.05) into polystyrene (PS) thin films. By controlling the ratio of the brush length (N) to that of the matrix polymers (P), we can selectively obtain dispersed or aggregated Au NR structures in the PS-Au(N):PS(P) films. A dispersion map of these structures allows one to choose N and P to obtain either uniformly dispersed Au NRs or aggregates of closely packed, side-by-side aligned Au NRs. Furthermore, by blending poly(2,6-dimethyl-p-phenylene oxide) (PPO) into the PS films, we demonstrate that the Au nanorod morphology can be further tuned by reducing depletion-attraction forces and promoting miscibility of the Au NRs. These predictable structures ultimately give rise to tunable optical absorption in the films resulting from surface plasmon resonance coupling between the Au NRs. Finally, self-consistent field theoretic (SCFT) calculations for both the PS-Au(N):PS(P) and PS-Au(N):PS(P):PPO systems provide insight into the PS brush structure, and allow us to interpret morphology and optical property results in terms of wet and dry PS brush states.

  4. Role of salt concentration in blend polymer for energy storage conversion devices

    NASA Astrophysics Data System (ADS)

    Arya, Anil; Sadiq, M.; Sharma, A. L.

    2016-05-01

    Solid Polymer Electrolytes (SPE) are materials of considerable interest worldwide, which serves dual purpose of electrolyte and separator between electrode compartments in renewable energy conversion/storage devices such as; high energy density batteries, electrochromic display devices, and supercapacitors. Polymer blend electrolytes are prepared for various concentration of salt (Ö/Li) with the constant ratio (0.5 gm) of each PEO and PAN polymers (blend polymer) using solution casting technique. Solid polymeric ionic conductor as a separator is the ultimate substitute to eliminate the drawback related to liquid and gel polymer ionic conductors. In the present work, solid polymer electrolyte film consisting of PEO, PAN and LiPF6 are examined for various concentration of lithium salt by keeping PEO/PAN blend ratio as a constant with a view to optimize the dominant salt concentration which could give the maximum conductivity at ambient temperature.

  5. Miscibility of eudragit/chitosan polymer blend in water determined by physical property measurements.

    PubMed

    Haque, Sk Ershadul; Sheela, A

    2013-01-30

    The interest in the preparation and application of polymeric blends is growing since they can exhibit properties of great industrial interest. The current study focuses on the preparation of polymeric blends of varying compositions of eudragit and chitosan and their miscibility studies. The preparation was carried out by using ethanol and 1% acetic acid in water. FT-IR spectra reveal the possibilities of chemical interactions between eudragit/chitosan. The miscibility of polymeric blend at different composition has been investigated by viscosity, ultrasonic velocity, density, refractive index and adiabatic compressibility values measured at two different temperatures 30 °C and 40 °C. The interaction parameters ΔB, μ and α, were determined from viscosity data. From the values observed, it is found that the blend is miscible in all compositions at 30 °C whereas at 40 °C, it seems to be immiscible in certain compositions. It is found that the blend is miscible, when the chitosan concentration is more than 70% (v/v) at both the temperatures and also observed that variation of temperature has no effect on the miscibility of eudragit/chitosan blend.

  6. Equilibrium Dynamics in the Nondiffusive Regime of an Entangled Polymer Blend

    SciTech Connect

    Lumma, D.; Borthwick, M. A.; Falus, P.; Lurio, L. B.; Mochrie, S. G. J.

    2001-03-05

    The dynamics of compositional fluctuations in a miscible, entangled homopolymer blend of poly(ethylene oxide) and poly(methyl methacrylate) were studied on length scales smaller than the polymer radii of gyration, and for times comparable to the polymers' disentanglement time. The measured relaxation rates are consistent with predictions of the reptation model, as expressed via the dynamic random-phase approximation. Moreover, the observed mode amplitudes allow for an estimate of the entanglement length in the blend.

  7. Tailoring nanoscale morphology of polymer: Fullerene blends using electrostatic field

    SciTech Connect

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; Lindemann, William; Wang, Wenjie; Grieser, Eric; Venkatesan, Swaminathan; Ngo, Evan; Bhattacharjee, Ujjal; Strzalka, Joseph; Jiang, Zhang; Qiao, Qiquan; Petrich, Jacob; Vaknin, David; Chaudhary, Sumit

    2016-12-05

    In this paper, to tailor the nanoscale phase separation in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to untreated sample (control); wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions – horizontal (H), tilted (T) and vertical (V) – relative to the plane of the substrate. Surface and bulk characterizations of field-treated BHJs affirm that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. E-field treatment yields thin films with large P3HT- and PCBM-rich domains acting as continuous pathways for efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10-4 ± 1.6 × 10-4 cm2 V-1 s-1 (117% higher than the control), and (2) power conversion efficient (PCE) of conventional and inverted OPVs recording 2.58 ± 0.02% and 4.1 ± 0.4%. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.

  8. Characterization of HPMC/PVP polymer blend films using WAXS technique

    NASA Astrophysics Data System (ADS)

    Prakash, Y.; Somashekarappa, H.; Parameswara, P.; Demappa, T.; Somashekar, R.

    2012-06-01

    Hydroxy propyl methyl cellulose (HPMC) and Poly vinyl pyrrolidone (PVP) polymer blend films were prepared and investigated using X-ray line profile analysis method. Here an attempt has been made to study the changes in the crystallite size and lattice strain in HPMC with the increase in concentration of PVP. Decrease in these microcrystalline parameters implies increase in the amorphous nature of the film giving more flexibility, degradability and good miscibility. Micro structural parameters reveals that the blend films have more amorphous nature than virgin HPMC. This further justified by SEM images which indicate better miscibility of the two polymers in the blend matrix.

  9. Biodegradable-Polymer-Blend-Based Surgical Sealant with Body-Temperature-Mediated Adhesion.

    PubMed

    Behrens, Adam M; Lee, Nora G; Casey, Brendan J; Srinivasan, Priya; Sikorski, Michael J; Daristotle, John L; Sandler, Anthony D; Kofinas, Peter

    2015-12-22

    The development of practical and efficient surgical sealants has the propensity to improve operational outcomes. A biodegradable polymer blend is fabricated as a nonwoven fiber mat in situ. After direct deposition onto the tissue of interest, the material transitions from a fiber mat to a film. This transition promotes polymer-substrate interfacial interactions leading to improved adhesion and surgical sealant performance.

  10. Hydrophilic-hydrophobic polymer blend for modulation of crystalline changes and molecular interactions in solid dispersion.

    PubMed

    Van Ngo, Hai; Nguyen, Phuc Kien; Van Vo, Toi; Duan, Wei; Tran, Van-Thanh; Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh

    2016-11-20

    This research study aimed to develop a new strategy for using a polymer blend in solid dispersion (SD) for dissolution enhancement of poorly water-soluble drugs. SDs with different blends of hydrophilic-hydrophobic polymers (zein/hydroxypropyl methylcellulose - zein/HPMC) were prepared using spray drying to modulate the drug crystal and polymer-drug interactions in SDs. Physicochemical characterizations, including power X-ray diffraction and Fourier transform infrared spectroscopy, were performed to elucidate the roles of the blends in SDs. Although hydrophobic polymers played a key role in changing the model drug from a crystal to an amorphous state, the dissolution rate was limited due to the wetting property. Fortunately, the hydrophilic-hydrophobic blend not only reduced the drug crystallinity but also resulted in a hydrogen bonding interaction between the drugs and the polymer for a dissolution rate improvement. This work may contribute to a new generation of solid dispersion using a blend of hydrophilic-hydrophobic polymers for an effective dissolution enhancement of poorly water-soluble drugs.

  11. Preparation and characterization of chitosan - polystyrene polymer blends

    NASA Astrophysics Data System (ADS)

    Mascarenhas, N. P.; Gonsalves, R. A.; Goveas, J. J.; Shetty, T. C. S.; Crasta, V.

    2016-05-01

    To enhance the physical and mechanical properties of Chitosan (CS) and to improve the functionality of CS towards some specific applications, we have blended CS with polystyrene (PS) to form blended films. The Fourier Transform Infrared Spectroscopy (FT-IR) has been performed on the prepared films to confirm functional groups and formation of the blends. Thermal analysis (TGA and DSC) is carried out to study thermal stability of the blended films. From X-ray diffraction (XRD) studies, the material reveals amorphous nature and hence it may be used for adsorption process. The versatility of the blends, such as film-forming ability, hydrophilicity, biodegradability and biocompatibility are comparable with the existing blends.

  12. Improved electrical properties of free standing blend polymer for renewable energy resources

    NASA Astrophysics Data System (ADS)

    Arya, Anil; Sharma, Sweety; Sharma, A. L.

    2016-05-01

    Blend polymer electrolytes are prepared for salt concentration (Ö/Li = 4) with the constant ratio (0.5 gm) of PEO and PAN using solution casting technique. The prepared free standing solid polymeric film is characterized by Field Emission Scanning Electron Microscopy (FESEM) which confirms the homogeneous distribution of dissociated salt in blend polymer matrix. After addition of salt the ionic conductivity value is found to be of the order of 7.13 × 10-5 Scm-1 which is three orders higher when compared with pure blend polymer films. The microscopic interaction among the polymer-ion, ion-ion has been confirmed by the Fourier Transform Infrared (FTIR) Spectroscopy. A very fine correlation has been built in the electrical conductivity and FTIR result. On the basis of above finding, a prepared free standing solid polymeric film appears to be appropriate for the energy storage/conversion device applications.

  13. Impedance studies of a green blend polymer electrolyte based on PVA and Aloe-vera

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, S.; Mathavan, T.; Vijaya, N.; Selvasekarapandian, Premalatha, M.; Monisha, S.

    2016-05-01

    The development of polymer electrolyte materials for energy generating and energy storage devices is a challenge today. A new type of blended green electrolyte based on Poly-vinyl alcohol (PVA) and Aloe-vera has been prepared by solution casting technique. The blending of polymers may lead to the increase in stability due to one polymer portraying itself as a mechanical stiffener and the other as a gelled matrix supported by the other. The prepared blend electrolytes were subjected to Ac impedance studies. It has been found out that the polymer film in which 1 gm of PVA was dissolved in 40 ml of Aloe-vera extract exhibits highest conductivity and its value is 3.08 × 10-4 S cm-1.

  14. Electrochemical characterization of electrospun nanocomposite polymer blend electrolyte fibrous membrane for lithium battery.

    PubMed

    Padmaraj, O; Rao, B Nageswara; Venkateswarlu, M; Satyanarayana, N

    2015-04-23

    Novel hybrid (organic/inorganic) electrospun nanocomposite polymer blend electrolyte fibrous membranes with the composition poly(vinylidene difluoride-co-hexafluoropropylene) [P(VdF-co-HFP)]/poly(methyl methacrylate) [P(MMA)]/magnesium aluminate (MgAl2O4)/LiPF6 were prepared by the electrospinning technique. All of the prepared electrospun P(VdF-co-HFP), PMMA blend [90% P(VdF-co-HFP)/10% PMMA], and nanocomposite polymer blend [90% P(VdF-co-HFP)/10% PMMA/x wt % MgAl2O4 (x = 2, 4, 6, and 8)] fibrous membranes were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The fibrous nanocomposite separator-cum-polymer blend electrolyte membranes were obtained by soaking the nanocomposite polymer blend membranes in an electrolyte solution containing 1 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, v/v). The newly developed fibrous nanocomposite polymer blend electrolyte [90% P(VdF-co-HFP)/10% PMMA/6 wt % MgAl2O4/LiPF6] membrane showed a low crystallinity, low average fiber diameter, high thermal stability, high electrolyte uptake, high conductivity (2.60 × 10(-3) S cm(-1)) at room temperature, and good potential stability above 4.5 V. The best properties of the fibrous nanocomposite polymer blend electrolyte (NCPBE) membrane with a 6 wt % MgAl2O4 filler content was used for the fabrication of a Li/NCPBE/LiCoO2 CR 2032 coin cell. The electrochemical performance of the fabricated CR 2032 cell was evaluated at a current density of 0.1 C-rate. The fabricated CR 2032 cell lithium battery using the newly developed NCPBE membrane delivered an initial discharge capacity of 166 mAh g(-1) and a stable cycle performance.

  15. Influence of film thickness on the phase separation mechanism in ultrathin conducting polymer blend films.

    PubMed

    Meier, Robert; Ruderer, Matthias A; Diethert, Alexander; Kaune, Gunar; Körstgens, Volker; Roth, Stephan V; Müller-Buschbaum, Peter

    2011-03-31

    The film morphology of thin polymer blend films based on poly[(1-methoxy)-4-(2-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and poly(N-vinylcarbazole) (PVK) is probed as a function of film thickness. Blend films are prepared with spin-coating of polymer solutions with different concentrations on top of solid supports. The blending ratio of both conducting polymers is kept constant. The film and surface morphology is probed with grazing incidence ultrasmall-angle X-ray scattering (GIUSAXS) and atomic force microscopy (AFM). A linear dependence between the film thickness and the averaged phase separation is found. In addition, X-ray reflectivity measurements show an enrichment of PVK at the substrate interface. UV/vis spectroscopy measurements indicate a linearly increasing amount of both homopolymers in the blend films for increasing film thicknesses. The generalized knowledge about the influence of the film thickness on the phase separation behavior in conducting polymer blend films is finally used to describe the phase separation formation during the spin-coating process, and the results are discussed in the framework of an adapted Flory-Huggins theory for rodlike polymers.

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

    NASA Astrophysics Data System (ADS)

    Chapi, Sharanappa; Niranjana, M.; Devendrappa, H.

    2016-05-01

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

  17. Phase Relations and Miscibility in Polymer Blends Containing Copolymers.

    DTIC Science & Technology

    1986-04-15

    Porter , R. S., Polymer Eng. Sci. 17, 534 (1977). 54. Roe, R. J., Fishkis, M., and Chang, J. C., Macromolecules 14, 1091 (1981). 55. Leibler, L...Kimura, M. and Porter , R. S., J. Polymer Sci.: Polymer Phys. Ed. 22, 1697 (1984). 113. Clas, S. D. and Eisenberg, A., J. Polymer Sci.: Polymer Phys. Ed... Diamant , J., Soong, D., and Williams, M. C., Polymer Eng. Sci. 22, 673 (1982). 147. Choi, G., Kaya, A., and Shen, M., Polymer Eng. Sci. 1_3, 231 (1973

  18. Fabrication and Optical Properties of Electrospun Conductive Polymer Nanofibers from Blended Polymer Solution

    NASA Astrophysics Data System (ADS)

    Chuangchote, Surawut; Sagawa, Takashi; Yoshikawa, Susumu

    2008-01-01

    Ultrafine poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV)/poly(vinyl pyrrolidone) (PVP) composite fibers with the average diameters ranging from 43 nm to 1.7 µm were prepared by electrospinning of blended polymer solutions in mixed solvent of chlorobenzene and methanol. The average diameter of the as-spun fibers was found to decrease into nanometer scale with decreasing the PVP concentration and/or addition of a volatile organic salt, pyridinium formate (PF). PVP was easily removed from MEH-PPV/PVP fibers by the Soxhlet extraction, and after the removal, pure MEH-PPV fibers were obtained as a ribbon-like structure aligned with wrinkled surface in fiber direction. Comparison with the cast film, as-spun fibers showed relatively higher crystallinity, higher conjugation length, and there was a remarkable blue shift of photoluminescence (PL) peak.

  19. Enhanced nanoscale imaging of polymer blends by temperature-controlled selective dissolution.

    PubMed

    Friedel, Bettina; Ehrler, Bruno; Hüttner, Sven; Greenham, Neil C

    2012-01-23

    Nanoscale imaging on polymer blends is vital, especially in organic electronics. By using temperature-controlled selective dissolution, the 3D structure of a thin film becomes accessible without the expensive search for adequate orthogonal solvents. The method, which takes advantage of the temperature dependence of the solubility, is demonstrated to image P3HT:PCBM and P3HT:F8TBT photovoltaic blend films using atomic force and scanning electron microscopy.

  20. AC conductivity and electrochemical studies of PVA/PEG based polymer blend electrolyte films

    NASA Astrophysics Data System (ADS)

    Polu, Anji Reddy; Kumar, Ranveer; Dehariya, Harsha

    2012-06-01

    Polymer blend electrolyte films based on Polyvinyl alcohol(PVA)/Poly(ethylene glycol)(PEG) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique. Conductivity in the temperature range 303-373 K and transference number measurements have been employed to investigate the charge transport in this polymer blend electrolyte system. The highest conductivity is found to be 9.63 × 10-5 S/cm at 30°C for sample with 30 weight percent of Mg(NO3)2 in PVA/PEG blend matrix. Transport number data shows that the charge transport in this polymer electrolyte system is predominantly due to ions. Using this electrolyte, an electrochemical cell with configuration Mg/(PVA+PEG+Mg(NO3)2)/(I2+C+electrolyte) was fabricated and its discharge characteristics profile has been studied.

  1. Investigations on Poly (ethylene oxide) (PEO) - blend based solid polymer electrolytes for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Koduru, H. K.; Iliev, M. T.; Kondamareddy, K. K.; Karashanova, D.; Vlakhov, T.; Zhao, X.-Z.; Scaramuzza, N.

    2016-10-01

    Polymer blend electrolytes based on Polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP), complexed with NaIO4 salt and Graphene oxide (GO) are investigated in the present report. The electrolytes are prepared by a facile solution cast technique. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) are employed to study the influence of ion-polymer interactions on the micro structural properties of blend electrolytes. Measurements of electrical conductivity of the blend polymer complexes have been performed by using complex impedance spectroscopy in the frequency range 1 Hz - 1 MHz and within the temperature range 303 K - 343 K.A study on electrical conductivity properties of GO doped ‘salt complexed electrolyte’ systems is presented.

  2. Structural, Optical and Mechanical properties of PVC/PMMA Polymer Blend by Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Patel, Gaurang; Sureshkumar, M. B.; Patel, Purvi

    2011-10-01

    PVC/PMMA polymer blends were characterized by Fourier Transform Infrared Spectroscopy (FTIR), UV-VIS Spectroscopy and mechanical analysis. The changes in mechanical properties are reflected by the changes in the IR spectrum. The mechanical properties of such poly blends revealed a substantial increase in Young's modulus and ultimate tensile strength after initial drop at 10% of PMMA. Optical properties such as the absorption coefficient, optical (Direct/Indirect) energy gap were calculated. The effects of different blending percentage on these parameters have been discussed and their results are co-related with IR study.

  3. Concentration fluctuations in miscible polymer blends: Influence of temperature and chain rigidity

    SciTech Connect

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

    2014-05-21

    In contrast to binary mixtures of small molecule fluids, homogeneous polymer blends exhibit relatively large concentration fluctuations that can strongly affect the transport properties of these complex fluids over wide ranges of temperatures and compositions. The spatial scale and intensity of these compositional fluctuations are studied by applying Kirkwood-Buff theory to model blends of linear semiflexible polymer chains with upper critical solution temperatures. The requisite quantities for determining the Kirkwood-Buff integrals are generated from the lattice cluster theory for the thermodynamics of the blend and from the generalization of the random phase approximation to compressible polymer mixtures. We explore how the scale and intensity of composition fluctuations in binary blends vary with the reduced temperature τ ≡ (T − T{sub c})/T (where T{sub c} is the critical temperature) and with the asymmetry in the rigidities of the components. Knowledge of these variations is crucial for understanding the dynamics of materials fabricated from polymer blends, and evidence supporting these expectations is briefly discussed.

  4. Formation of ion clusters in the phase separated structures of neutral-charged polymer blends

    NASA Astrophysics Data System (ADS)

    Kwon, Ha-Kyung; Olvera de La Cruz, Monica

    2015-03-01

    Polyelectrolyte blends, consisting of at least one charged species, are promising candidate materials for fuel cell membranes, for their mechanical stability and high selectivity for proton conduction. The phase behavior of the blends is important to understand, as this can significantly affect the performance of the device. The phase behavior is controlled by χN, the Flory-Huggins parameter multiplied by the number of mers, as well as the electrostatic interactions between the charged backbone and the counterions. It has recently been shown that local ionic correlations, incorporated via liquid state (LS) theory, enhance phase separation of the blend, even in the absence of polymer interactions. In this study, we show phase diagrams of neutral-charged polymer blends including ionic correlations via LS theory. In addition to enhanced phase separation at low χN, the blends show liquid-liquid phase separation at high electrostatic interaction strengths. Above the critical strength, the charged polymer phase separates into ion-rich and ion-poor regions, resulting in the formation of ion clusters within the charged polymer phase. This can be shown by the appearance of multiple spinodal and critical points, indicating the coexistence of several charge separated phases. This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

  5. Synthesis and characterization of alkaline polyvinyl alcohol and poly(epichlorohydrin) blend polymer electrolytes and performance in electrochemical cells

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lin, Sheng-Jen; Hsu, Sung-Ting

    Alkaline SPE was obtained from a blend of polyvinyl alcohol (PVA) and poly(epichlorohydrin) (PECH), PVA-PECH, by a solution-cast technique. The PVA host polymer is blended with PECH polymer to provide a polymer electrolyte with improved chemical and mechanical properties. The ionic conductivity of the PVA-PECH polymer electrolytes is between 10 -2 and 10 -3 S cm -1 at room temperature when the blend ratio is varied from 1:0.2 to 1:1. The PVA-PECH polymer was characterized by means of scanning electron microscopy, X-ray diffraction, stress-strain test, cyclic voltammetry, and a.c. impedance spectroscopy. It is found that the polymer electrolytes exhibit good mechanical strength and excellent chemical stability. The electrochemical performance of solid-state Zn-air batteries with various types of the blended polymer electrolyte films is examined by a galvanostatic discharge method.

  6. Hot Hole Transfer Increasing Polaron Yields in Hybrid Conjugated Polymer/PbS Blends.

    PubMed

    Strein, Elisabeth; deQuilettes, Dane W; Hsieh, Stephen T; Colbert, Adam E; Ginger, David S

    2014-01-02

    We use quasi-steady-state photoinduced absorption (PIA) to study charge generation in blends of poly(3-hexylthiophene-2,5-diyl) (P3HT) with PbS nanocrystal quantum dots as a function of excitation energy. We find that, per photon absorbed, the yield of photogenerated holes present on the conjugated polymer increases with pump energy, even at wavelengths where only the quantum dots absorb. We interpret this result as direct evidence for transfer of hot holes in these conjugated polymer/quantum dot blends. These results help understand the operation of hybrid organic/inorganic photovoltaics.

  7. Nanoparticle free polymer blends for light scattering films in liquid crystal displays

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi; Mochiduki, Kazuhide; Kubo, Naoya; Yokoyama, Yoshiyuki

    2012-06-01

    This paper reports an approach using nanoparticle free polymer blends for light scattering films in liquid crystal displays. The ability to create the regularly structured circle of approximately 200 nm diameter in the light scattering film by blending two specified polymers with carboxylic acid groups and epoxy groups was demonstrated. The developed light scattering film based on thermosetting system indicated regularly structured nanomorphology, high light scattering rates of more than 3.9% at 300-600 nm of wavelength, and fast thermal cross-linking reaction at 150 °C and 60 s in thermosetting conditions for high productivity.

  8. Efficacy of Different Block Copolymers in Facilitating Microemulsion Phases in Polymer Blend Systems

    NASA Astrophysics Data System (ADS)

    Pandav, Gunja; Ganesan, Venkat

    2014-03-01

    Polymeric microemulsions are formed in a narrow range of phase diagram when a blend of immiscible homopolymers is compatibilized by copolymers. In this study, we consider the ternary blend system of A and B homopolymers mixed with block copolymers containing A and B segments, and probe the efficacy of different copolymer configurations in promoting the formation of microemulsion phases. Specifically, we consider: (a) Monodisperse diblock copolymers; (b) Diblock copolymers with bidisperse molecular weights (MW); (c) Block copolymers having MW polydispersity in one of the blocks; (d) Diblock copolymers having monodisperse MW but bidispersity in average composition; and (e) Gradient copolymers exhibiting a linear variation in the average composition. Using single chain in mean field simulations effected in two dimensions, we probe the onset of formation and the width of the bicontinuous microemulsion channel in the ternary phase diagram of homopolymer blended with compatibilizer. We rationalize our results by explicitly quantifying the interfacial activity and the influence of fluctuation effects in the respective copolymer systems.

  9. The Viscoelastic Behavior of Polymer/Oligomer Blends

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; McKenna, Gregory; Simon, Sindee

    2009-03-01

    The dynamics in athermal blends of poly(α-methyl styrene) (PaMS) and its short chain oligomer are investigated using rheometry and differential scanning calorimetry (DSC). Master curves for the dynamic shear responses, G' and G", are successfully constructed for both the pure materials and the blends, indicating the validity of the time-temperature superposition principle. The temperature dependence of the shift factor follows the WLF (Williams-Landel-Ferry) behavior over the temperature range studied, and for the blends, the dependence is dominated by the high mobility oligomer. The discrete relaxation spectra of the materials are calculated and are found to be broader for the blends than for the pure materials. A similar domination of the dynamics by the oligomer is observed in DSC enthalpy recovery studies and in the broadened glass transition from DSC. The ability to predict the dynamic responses of the blends from the responses of the neat materials is examined, and whether this prediction needs to incorporate the self-concentration idea as described in Colmenero's model will be discussed.

  10. Unraveling Structure-Property Relationships in Polymer Blends for Intelligent Materials Design

    NASA Astrophysics Data System (ADS)

    Irwin, Matthew Tyler

    Block polymers provide an accessible route to structured, composite materials by combining two or more components with disparate mechanical, chemical, and electrical properties into a single bulk material with nanoscale domains. However, the characteristic lengthscale of these systems is limited, and the choice of components is restricted to those that are able to undergo microstructural ordering at accessible temperatures. This thesis details routes to overcoming these limitations through the addition of a lithium salt, a blend of homopolymers, or both. Chapter 2 describes a study wherein complex sphere phases such as the Frank-Kasper sigma phase can be observed in otherwise disordered asymmetric block polymers through the addition of a lithium salt. Chapter 3 discusses the development and characterization of a ternary polymer blend of an AB diblock copolymer and A and B homopolymers doped with a lithium salt. Detailed characterization showed that doping blends that are otherwise disordered with lithium salt induced microstructural ordering and largely recovers the phase behavior of traditional ternary polymer blends. A systematic study of the ionic conductivity of the blends at a fixed salt concentration demonstrates that, at a given composition, disordered, yet highly structured blends consistently exhibit better conductivity than polycrystalline morphologies with long range order. Chapter 4 extends the methodology of Chapter 3 and details a systematic study of the effects of cross-linker concentration on the performance of polymer electrolyte membranes produced via polymerization-induced microphase separation that exhibit a highly structured, globally disordered microstructure. Finally, Chapter 5 details efforts to develop a water filtration membrane using a polyethylene template derived from a polymeric bicontinuous microemulsion. Throughout all of this work, the goal is to better understand structure-property relationships at the molecular level in order to

  11. Surface-Induced First-Order Transition in Athermal Polymer-Nanoparticle Blends

    NASA Astrophysics Data System (ADS)

    McGarrity, E. S.; Frischknecht, A. L.; Frink, L. J. D.; Mackay, M. E.

    2007-12-01

    We investigate the phase behavior of athermal polymer-nanoparticle blends near a substrate. We apply a recent fluids density functional theory of Tripathi and Chapman to a simple model of the blend as a mixture of hard spheres and freely jointed hard chains, near a hard wall. We find that there is a first-order phase transition in which the nanoparticles expel the polymer from the surface to form a monolayer. The nanoparticle transition density depends on the length of the polymer and the overall bulk density of the system. The effect is due both to packing entropy effects related to size asymmetry between the components and to the polymer configurational entropy. The simplicity of the system allows us to understand the so-called “entropic-push” observed in experiments.

  12. Morphological analysis of Polyethersulfone/polyvinyl Acetate blend membrane synthesized at various polymer concentrations

    NASA Astrophysics Data System (ADS)

    Hadi, S. H. A. A.; Mannan, H. A.; Mukhtar, H.; Shaharun, M. S.; Murugesan, T.

    2016-06-01

    This paper reports the effect of varying polymer concentration i.e. solvent/polymer ratio on the morphology and gas transport behaviour of polyethersulfone/polyvinyl acetate blend membrane. The solvent used was dimethylformamide, while the manipulated variable was polymer concentration. The concentrations were varied from 75-90 weight % solvent. A homogeneous surface with dense cross-section structure membranes were successfully developed as deduced from FESEM images. The permeability of CO2 and CH4 gases increased with increasing polymer concentration and an improved CO2/CH4 selectivity was observed. These observation made from the characterization justified the applicability of the blend to be synthesized as membrane for gas separation.

  13. Ultra-flexible nonvolatile memory based on donor-acceptor diketopyrrolopyrrole polymer blends

    PubMed Central

    Zhou, Ye; Han, Su-Ting; Yan, Yan; Zhou, Li; Huang, Long-Biao; Zhuang, Jiaqing; Sonar, Prashant; Roy, V. A. L.

    2015-01-01

    Flexible memory cell array based on high mobility donor-acceptor diketopyrrolopyrrole polymer has been demonstrated. The memory cell exhibits low read voltage, high cell-to-cell uniformity and good mechanical flexibility, and has reliable retention and endurance memory performance. The electrical properties of the memory devices are systematically investigated and modeled. Our results suggest that the polymer blends provide an important step towards high-density flexible nonvolatile memory devices. PMID:26029856

  14. Fabrication and characterization of polymer blends and composites derived from biopolymers

    NASA Astrophysics Data System (ADS)

    Sharma, Suraj

    This research focuses on fabricating blends and composites from natural polymers especially from proteins and natural epoxy, and describing the properties of plastics made from them. Specifically, plastic samples from partially denatured feathermeal and bloodmeal proteins, derived from the animal co-products (rendering) industry, were successfully produced through a compression molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. Therefore, this study explored blending methods for improving the toughness. Plastic forming conditions for undenatured animal proteins such as chicken egg whites albumin and whey, used as a model, were established to prepare plastics from their blends with animal co-product proteins. The resultant plastic samples from these biomacromolecular blends demonstrated improved mechanical properties that were also compared with the established theoretical models known for polymer blends and composites. Moreover, plastics from albumin of chicken egg whites and human serum have demonstrated their potential in medical applications that require antibacterial properties. Another natural polymer vegetable oil-based epoxy, especially epoxidized linseed oil, showed significant potential to replace petroleum-derived resins for use as a matrix for composites in structural applications. Moreover, the research showed the benefits of ultrasonic curing, which can help in preparing the out-of-autoclave composites.

  15. Improvement of impact strength in linear low density polyethylene (LLDPE) by blending with amorphous polymers

    SciTech Connect

    Mirabella, F.M. Jr.

    1996-12-31

    The objective of the current work was to improve the film impact strength of commercial linear low density polyethylene (LLDPE) resins, while maintaining or improving other desirable properties. The approach used was to blend rubber-like (i.e. essentially noncrystalline) polymer resins with the base resin LLDPE. The choice of the rubber-like components was largely dictated by their commercial availability. The rubber-like polymers chosen were poly (ethylene-vinyl acetate) [EVA], poly (ethylene-n-butyl acrylate) [EnBA], and poly (ethylene-propylene) rubber [EPR]. The weight percent range of addition of the rubber-like component was restricted to 5% - 20%. The preferred range was only up to 10%. The structure of the base LLDPE resin, rubber-like components and the blends thereof was characterized. The physical and mechanical properties of the blown films of the resin blends were measured and correlations between structure and properties were determined.

  16. Correlating structure with fluorescence emission in phase-separated conjugated-polymer blends.

    PubMed

    Chappell, John; Lidzey, David G; Jukes, Paul C; Higgins, Anthony M; Thompson, Richard L; O'Connor, Stephen; Grizzi, Ilaria; Fletcher, Robert; O'Brien, Jim; Geoghegan, Mark; Jones, Richard A L

    2003-09-01

    Blends of conjugated polymers are frequently used as the active semiconducting layer in light-emitting diodes and photovoltaic devices. Here we report the use of scanning near-field optical microscopy, scanning force microscopy and nuclear-reaction analysis to study the structure of a thin film of a phase-separated blend of two conjugated polymers prepared by spin-casting. We show that in addition to the well-known micrometre-scale phase-separated morphology of the blend, one of the polymers preferentially wets the surface and forms a 10-nm-thick, partially crystallized wetting layer. Using near-field microscopy we identify unexpected changes in the fluorescence emission from the blend that occurs in a 300-nm-wide band located at the interface between the different phase-separated domains. Our measurements provide an insight into the complex structure of phase-separated conjugated-polymer thin films. Characterizing and controlling the properties of the interfaces in such films will be critical in the further development of efficient optoelectronic devices.

  17. Shape-memory effect by specific biodegradable polymer blending for biomedical applications.

    PubMed

    Cha, Kook Jin; Lih, Eugene; Choi, Jiyeon; Joung, Yoon Ki; Ahn, Dong Jun; Han, Dong Keun

    2014-05-01

    Specific biodegradable polymers having shape-memory properties through "polymer-blend" method are investigated and their shape-switching in body temperature (37 °C) is characterized. Poly(L-lactide-co-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA) are dissolved in chloroform and the films of several blending ratios of PLCL/PLGA are prepared by solvent casting. The shape-memory properties of films are also examined using dynamic mechanical analysis (DMA). Among the blending ratios, the PLCL50/PLGA50 film shows good performance of shape-fixity and shape-recovery based on glass transition temperature. It displays that the degree of shape recovery is 100% at 37 °C and the shape recovery proceeds within only 15 s. In vitro biocompatibility studies are shown to have good blood compatibility and cytocompatibility for the PLCL50/PLGA50 films. It is expected that this blended biodegradable polymer can be potentially used as a material for blood-contacting medical devices such as a self-expended vascular polymer stents and vascular closure devices in biomedical applications.

  18. Conjugated Polymer Blend Microspheres for Efficient, Long-Range Light Energy Transfer.

    PubMed

    Kushida, Soh; Braam, Daniel; Dao, Thang Duy; Saito, Hitoshi; Shibasaki, Kosuke; Ishii, Satoshi; Nagao, Tadaaki; Saeki, Akinori; Kuwabara, Junpei; Kanbara, Takaki; Kijima, Masashi; Lorke, Axel; Yamamoto, Yohei

    2016-05-24

    Highly luminescent π-conjugated polymeric microspheres were fabricated through self-assembly of energy-donating and energy-accepting polymers and their blends. To avoid macroscopic phase separation, the nucleation time and growth rate of each polymer in the solution were properly adjusted. Photoluminescence (PL) studies showed that efficient donor-to-acceptor energy transfer takes place inside the microspheres, revealing that two polymers are well-blended in the microspheres. Focused laser irradiation of a single microsphere excites whispering gallery modes (WGMs), where PL generated inside the sphere is confined and resonates. The wavelengths of the PL lines are finely tuned by changing the blending ratio, accompanying the systematic yellow-to-red color change. Furthermore, when several microspheres are coupled linearly, the confined PL propagates the microspheres through the contact point, and a cascade-like process converts the PL color while maintaining the WGM characteristics. The self-assembly strategy for the formation of polymeric nano- to microstructures with highly miscible polymer blends will be advantageous for optoelectronic and photonic device applications.

  19. Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

    NASA Astrophysics Data System (ADS)

    Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

    2015-04-01

    We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/μg and 1.72(14) nL/μg were found for Milli-Q water and lysis-binding buffer, respectively.

  20. The Effects of Branching and Deuterium Labeling on Polymer Blend Miscibility

    NASA Astrophysics Data System (ADS)

    Defelice, Jeffrey; Higgins, Julia; Lipson, Jane

    Local structural or chemical changes made to one component of a polymer blend can have a significant impact on miscibility. In this talk we will focus on several blends involving linear and 4-arm star polystyrene (PS), both hydrogenous and deuterated, and poly(vinylmethylether) (PVME). We consider the effect of the structural change on the miscibility of PS/PVME, then turn to the added effect of deuterium labeling, both on this blend and for isotopic PS mixtures. Using our Locally Correlated Lattice (LCL) model we are able to identify trends in the physical properties of pure components, such as: free volume, thermal expansion coefficient, and cohesive energy density. We find that branching and labeling, both independently and cumulatively, affect pure component properties. Our ability to correlate structural and chemical changes with trends in physical properties leads to predictions about the compatibility of pure components, and thus their blend miscibility. The authors gratefully acknowledge support from NSF DMR-1403757 and GAANN.

  1. Property modification of Nafion via polymer blending with ethylene vinyl alcohol "polyimide" (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hwang, Taeseon; Nam, Jungsoo; Shen, Qi; Trabia, Sarah; Suhr, Jonghwan; Lee, Dong-Chan; Kim, Kwang Jin

    2016-04-01

    The blended ion exchange membrane between Nafion and ethylene vinyl alcohol (EVOH) was used for fabrication of the ionic polymer-metal composite (IPMC) to redeem inherent drawbacks of Nafion such as high cost or environment-unfriendliness. EVOH solution was blended in Nafion solution by a volume ratio of 15 and 30 % membranes were prepared through solution casting method. The prepared blended Nafion membranes can be fabricated IPMCs with deposition of platinum electrode onto its surface without crack or delamination. The surface resistance of all prepared IPMCs is measured through 2 point probe. This study investigated the chemical structure and thermal properties of prepared membranes. Moreover, we characterized the cross-section morphology and studied the electromechanical performances (displacement and blocking force) of prepared IPMC actuators. The IPMC actuators with proposed blended Nafion membranes were demonstrated comparable electromechanical performance by significantly reducing the content of Nafion.

  2. The effect of polymer blends on release profiles of diclofenac sodium from matrices.

    PubMed

    Samani, Soliman Mohammadi; Montaseri, Hashem; Kazemi, Abdolghani

    2003-05-01

    The purpose of this study was to evaluate the effect of polymer blends on the in vitro release profile of diclofenac sodium. Several controlled release matrices of diclofenac sodium with different proportions of hydroxypropyl methylcellulose (HPMC; viscosity grade 60 and 500 mPa.s), carbopol 940 and lactose as a water soluble filler were prepared. The results showed that when HPMC (viscosity grade 60 mPa.s) alone was used as matrix former, diclofenac sodium was released fast but the release rate became slower with HPMC (viscosity grade 500 mPa.s) at higher polymer/drug ratios (more than 0.8:1). However in lower polymer/drug ratios (lower than 0.7:1) the release rate still was fast. The results showed that carbopol can extend the release time appreciably but the release profiles had considerable fluctuations, and drug release in first hours was slow but increased appreciably with time at the end of profiles. When an appropriate blend of HPMC (viscosity grade 60 or 500 mPa.s) and carbopol 940 was used, the drug release became more uniform and its kinetic approached to zero order and release fluctuations were diminished. The results with these polymer blends showed that it is possible to reduce the total amounts of polymer in each formulation. According to kinetic analysis data, drug release from these matrix tablets did not follow Fick's law of diffusion and the results were in agreement with the earlier reports.

  3. Linear correlation between rheological, mechanical and mucoadhesive properties of polycarbophil polymer blends for biomedical applications.

    PubMed

    De Souza Ferreira, Sabrina Barbosa; Da Silva, Jéssica Bassi; Borghi-Pangoni, Fernanda Belincanta; Junqueira, Mariana Volpato; Bruschi, Marcos Luciano

    2017-02-14

    Polycarbophil is widely used in a variety of pharmaceutical formulations, mainly for their strong ability to adhere to the epithelial and mucous barriers (bio/mucoadhesion). On the other hand, its association with the thermoresponsive polymer (poloxamer 407) has been poorly explored. This work investigates the rheological, mechanical and mucoadhesive properties of polymer blends containing polycarbophil and poloxamer 407, in order to select the best formulations for biomedical and pharmaceutical applications. Mechanical (hardness, compressibility, adhesiveness, softness, and mucoadhesion) and rheological characteristics (consistency index, yield value and hysteresis area) showed that 20% (w/w) poloxamer 407- polymer blends exhibited higher values parameters. However, the rheological interaction parameter, which was more sensible than the mechanical interaction parameter, revealed higher synergism for systems comprising 15% (w/w) poloxamer 407, due to the system organization and polymers' properties. Furthermore, gelation temperatures were appropriated, suggesting that polymer blends can be used as biomedical materials, and displaying easy administration, enhanced retention and prolonged residence time at the site of application. Therefore, rheological, mechanical and mucoadhesive characterization provided a rational basis for selecting appropriated systems, useful for mucoadhesive drug delivery systems and biomedical applications.

  4. Polyethylene-supported polyvinylidene fluoride-cellulose acetate butyrate blended polymer electrolyte for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Liu, Jiansheng; Li, Weishan; Zuo, Xiaoxi; Liu, Shengqi; Li, Zhao

    2013-03-01

    The polyethylene (PE)-supported polymer membranes based on the blended polyvinylidene fluoride (PVDF) and cellulose acetate butyrate (CAB) are prepared for gel polymer electrolyte (GPE) of lithium ion battery. The performances of the prepared membranes and the resulting GPEs are investigated by scanning electron microscopy, electrochemical impedance spectroscopy, linear potential sweep, and charge-discharge test. The effect of the ratio of PVDF to CAB on the performance of the prepared membranes is considered. It is found that the GPE based on the blended polymer with PVDF:CAB = 2:1 (in weight) has the largest ionic conductivity (2.48 × 10-3 S cm-1) and shows good compatibility with anode and cathode of lithium ion battery. The LiCoO2/graphite battery using this GPE exhibits superior cyclic stability at room temperature, storage performance at elevated temperature, and rate performance.

  5. Electron and Hole Contributions to the Terahertz Photoconductivity of a Conjugated Polymer:Fullerene Blend Identified.

    PubMed

    Ponseca, Carlito S; Němec, Hynek; Vukmirović, Nenad; Fusco, Sandra; Wang, Ergang; Andersson, Mats R; Chabera, Pavel; Yartsev, Arkady; Sundström, Villy

    2012-09-06

    Time-resolved terahertz spectroscopy was employed for the investigation of charge-transport dynamics in benzothiadiazolo-dithiophene polyfluorene ([2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]) (APFO-3) polymers with various chain lengths and in its monomer form, all blended with an electron acceptor ([6,6]-phenyl-C61-butyric acid methyl ester, PCBM). Upon photoexcitation, charged polaron pairs are created, negative charges are transferred to fullerenes, while positive polarons remain on polymers/monomers. Vastly different hole mobility in polymer and monomer blends allows us to distinguish the hole and electron contributions to the carrier mobility.

  6. Molecular Theory Studies of Polymer/Nanoparticle Blends Near Surfaces

    NASA Astrophysics Data System (ADS)

    McGarrity, Erin; Frischknecht, Amalie; Mackay, Michael

    2007-03-01

    Recent experimental results have shown that nanoparticles added to supported thin polymer films can inhibit dewetting by migrating to the substrate. To better understand this phenomenon, we use a classical density functional theory developed by Tripathi and Chapman. The effects of nanoparticle radius and density are examined. Preliminary results for hard-particle hard-chain systems indicate that regular layered structures emerge when a critical density is reached and the particles displace the polymers near the substrate. The effects of particle and polymer attractions and substrate potentials are currently being studied. We also compare our results to molecular simulations.

  7. Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

    SciTech Connect

    Putri, Zufira E-mail: arcana@chem.itb.ac.id; Arcana, I Made E-mail: arcana@chem.itb.ac.id

    2014-03-24

    Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO{sub 2} are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes to be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO{sub 2} compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO{sub 2} blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM)

  8. Long-Term Sustained Ciprofloxacin Release from PMMA and Hydrophilic Polymer Blended Nanofibers.

    PubMed

    Zupančič, Špela; Sinha-Ray, Sumit; Sinha-Ray, Suman; Kristl, Julijana; Yarin, Alexander L

    2016-01-04

    Nanofibers represent an attractive novel drug delivery system for prolonged and controlled release. However, sustained release of hydrophilic drugs, like ciprofloxacin hydrochloride (CIP), from polymeric nanofibers is not an easy task. The present study investigates the effect of different hydrophobic polymers (PCL and PMMA) alone in monolithic nanofibers or with hydrophilic polymers (PVA, PEO, and chitosan) in blended nanofibers aiming to achieve sustained CIP release. CIP release from PCL nanofibers was 46% and from PMMA just 1.5% over 40 day period. Thus, PMMA holds great promise for modification of CIP release from blended nanofibers. PMMA blends with 10% PEO, PVA, or chitosan were used to electrospin nanofibers from solution in the mixture of acetic and formic acid. These nanofibers exhibited different drug-release profiles: PEO containing nanofiber mats demonstrated high burst effect, chitosan containing mats revealed very slow gradual release, and PVA containing mats yielded smaller burst effect with favorable sustained release. We have also shown that gradual sustain release of antibiotic like CIP can be additionally tuned over 18 days with various blend ratios of PMMA with PVA or chitosan reaching almost 100%. A mathematical model in agreement with the experimental observation revealed that the sustained CIP release from the blended nanofibers corresponded to the two-stage desorption process.

  9. Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Putri, Zufira; Arcana, I. Made

    2014-03-01

    Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO2 are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes to be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO2 compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO2 blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM).

  10. Structure property relationships in polymer blends and composites. Part I. Polymer/POSS composites. Part II. Poly(ethylene terephthalate) ionomer/polyamide 6 blends. Part III. Elastomer/boron nitride composites

    NASA Astrophysics Data System (ADS)

    Iyer, Subramanian

    Multiphase polymer systems are an increasingly important technical area of polymer science. By definition, a multiphase system is one that has two or more distinct phases. From the standpoint of commercial applications and developments, polymer blending represents one of the easiest ways to achieve properties not available in individual materials. This work discusses the structure property relationships in polymer certain blends and composites. Polymer/polyhedral oligomeric silsesquioxanes (POSSRTM) blends and copolymers have gained significant attention in the last decade due the unique properties of the inorganic-organic hybrid structure of POSS. The majority of the research in polymer/POSS has been in the form of copolymers and thermosets. The criteria for the reinforcement of polymers using POSS as a filler material is not been discussed in literature. Part I of the thesis will highlight the effect of blending POSS with different polymers and discuss the rules for reinforcement of polymers when using POSS as a filler material. Part II of the thesis will discuss the structure property relationships in poly(ethylene terephthalate) ionomer/polyamide 6 blends. Part III will discuss the control of coefficient of thermal expansion of elastomers using boron nitride as a filler material.

  11. Bright and efficient blue light-emitting diodes based on conjugated polymer blends

    NASA Astrophysics Data System (ADS)

    Palilis, Leonidas C.; Lidzey, David G.; Redecker, Michael; Bradley, Donal D. C.; Inbasekaran, Michael; Woo, Edmund P.; Wu, Weishi W.

    1999-12-01

    We report on the fabrication and properties of single layer blue light-emitting diodes (LEDs) based on conjugated polymer blends. We have used poly(9,9-dioctylfluorene) (PFO) as the host and a hole transport triarylamine/fluorene copolymer as the guest. Despite the fact that the photoluminescence quantum efficiency of the blend is lower compared than that of the host and guest polymers on their own, an enhancement in both the electroluminescence quantum and power efficiency is seen for the blend. This observation indicates that the hole transport material leads to a significant improvement in hole injection and transport and a greatly improved charge carrier balance factor. A careful comparison of the photoluminescence and the electroluminescence spectra reveals that more emission originates from the guest polymer for electroluminescence than for photoluminescence. This can be rationalized by the expectation that both Forster transfer and charge transfer from the host to the guest occur under electrical operation of the device. Only Forster transfer is expected for optical excitation. A much higher brightness and a lower turn on and operating voltage is achieved for the blend. The emission from our optimized blue single layer LED reaches a maximum brightness of 1550 cd/m2 and has a maximum external quantum efficiency of .4% and a maximum power efficiency of 0.3 lm/W.

  12. Mechanical properties of heterophase polymer blends of cryogenically fractured soy flour composite filler and poly(styrene-butadiene)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reinforcement effect of cryogenically fractured soy Flour composite filler in soft polymer was investigated in this study. Polymer composites were prepared by melt-mixing polymer and soy flour composite fillers in an internal mixer. Soy flour composite fillers were prepared by blending aqueous dis...

  13. Wetting in a phase separating polymer blend film: quench depth dependence

    PubMed

    Geoghegan; Ermer; Jungst; Krausch; Brenn

    2000-07-01

    We have used 3He nuclear reaction analysis to measure the growth of the wetting layer as a function of immiscibility (quench depth) in blends of deuterated polystyrene and poly(alpha-methylstyrene) undergoing surface-directed spinodal decomposition. We are able to identify three different laws for the surface layer growth with time t. For the deepest quenches, the forces driving phase separation dominate (high thermal noise) and the surface layer grows with a t(1/3) coarsening behavior. For shallower quenches, a logarithmic behavior is observed, indicative of a low noise system. The crossover from logarithmic growth to t(1/3) behavior is close to where a wetting transition should occur. We also discuss the possibility of a "plating transition" extending complete wetting to deeper quenches by comparing the surface field with thermal noise. For the shallowest quench, a critical blend exhibits a t(1/2) behavior. We believe this surface layer growth is driven by the curvature of domains at the surface and shows how the wetting layer forms in the absence of thermal noise. This suggestion is reinforced by a slower growth at later times, indicating that the surface domains have coalesced. Atomic force microscopy measurements in each of the different regimes further support the above. The surface in the region of t(1/3) growth is initially somewhat rougher than that in the regime of logarithmic growth, indicating the existence of droplets at the surface.

  14. Polymer ligand–induced autonomous sorting and reversible phase separation in binary particle blends

    PubMed Central

    Schmitt, Michael; Zhang, Jianan; Lee, Jaejun; Lee, Bongjoon; Ning, Xin; Zhang, Ren; Karim, Alamgir; Davis, Robert F.; Matyjaszewski, Krzysztof; Bockstaller, Michael R.

    2016-01-01

    The tethering of ligands to nanoparticles has emerged as an important strategy to control interactions and organization in particle assembly structures. We demonstrate that ligand interactions in mixtures of polymer-tethered nanoparticles (which are modified with distinct types of polymer chains) can impart upper or lower critical solution temperature (UCST/LCST)–type phase behavior on binary particle mixtures in analogy to the phase behavior of the corresponding linear polymer blends. Therefore, cooling (or heating) of polymer-tethered particle blends with appropriate architecture to temperatures below (or above) the UCST (or LCST) results in the organization of the individual particle constituents into monotype microdomain structures. The shape (bicontinuous or island-type) and lengthscale of particle microdomains can be tuned by variation of the composition and thermal process conditions. Thermal cycling of LCST particle brush blends through the critical temperature enables the reversible growth and dissolution of monoparticle domain structures. The ability to autonomously and reversibly organize multicomponent particle mixtures into monotype microdomain structures could enable transformative advances in the high-throughput fabrication of solid films with tailored and mutable structures and properties that play an important role in a range of nanoparticle-based material technologies. PMID:28028538

  15. Characterization of Homopolymer and Polymer Blend Films by Phase Sensitive Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Ngwa, Wilfred; Wannemacher, Reinhold; Grill, Wolfgang

    2003-03-01

    CHARACTERIZATION OF HOMOPOLYMER AND POLYMER BLEND FILMS BY PHASE SENSITIVE ACOUSTIC MICROSCOPY W Ngwa, R Wannemacher, W Grill Institute of Experimental Physics II, University of Leipzig, 04103 Leipzig, Germany Abstract We have used phase sensitive acoustic microscopy (PSAM) to study homopolymer thin films of polystyrene (PS) and poly (methyl methacrylate) (PMMA), as well as PS/PMMA blend films. We show from our results that PSAM can be used as a complementary and highly valuable technique for elucidating the three-dimensional (3D) morphology and micromechanical properties of thin films. Three-dimensional image acquisition with vector contrast provides the basis for: complex V(z) analysis (per image pixel), 3D image processing, height profiling, and subsurface image analysis of the polymer films. Results show good agreement with previous studies. In addition, important new information on the three dimensional structure and properties of polymer films is obtained. Homopolymer film structure analysis reveals (pseudo-) dewetting by retraction of droplets, resulting in a morphology that can serve as a starting point for the analysis of polymer blend thin films. The outcome of confocal laser scanning microscopy studies, performed on the same samples are correlated with the obtained results. Advantages and limitations of PSAM are discussed.

  16. Correlation between free-volume parameters and physical properties of polyethylene-nitrile rubber blend

    NASA Astrophysics Data System (ADS)

    Gomaa, E.; Mostafa, N.; Mohsen, M.; Mohammed, M.

    2004-10-01

    Positron annihilation lifetime spectroscopy (PALS) was used to study the immiscibility of a polar nitrile rubber (NBR) that had been blended with pure and waste, low- and high-density polyethylene (PE). The effect of the weight percent of the rubber added to the PE was also investigated. It was found that a complicated variation (positive and negative) in both free-volume parameters (τ3 and I 3) from the values of the initial polymers forms an immiscible blend. These results are supported by a significant broadening in the free-volume hole size distributions. This has been interpreted in terms of interfacial spaces created between the boundaries of the two phases. Furthermore, a correlation was established between the free-volume parameters (τ3 and I 3) and the electrical and mechanical properties of the before mentioned polymer blends as a function of the weight percent of waste PE.

  17. Time-of-flight photoconductivity in polymer/graphene blends

    NASA Astrophysics Data System (ADS)

    Bratina, Gvido; Pavlica, Egon; Pathipati, Srinivasa Rao; Nawrocki, Robert; Penumala, Raveendra

    2015-03-01

    We have used time-of-flight (TOF) photoconductivity measurements to assess the electric charge transport parameters in thin layers of poly(3-hexyl thiophene-2,5-diyl) (P3HT) mixed with single and multiple-layer graphene nanoflakes. Thin layers were cast from a solution and two co-planar metal electrodes were deposited by vacuum evaporation on top. An electric field was set up between the electrodes A laser pulse was used to photogenerate charge carriers near the biased electrode, and time dependence of the photocurrent (I(t)) was measured at the opposite electrode. I(t) curves were confronted to I(t)s obtained by a Gaussian-disorder Monte Carlo simulations, adapted to thin-film geometry. The simulations included a position-dependent electric field between two coplanar electrodes, which importantly affects the charge carrier transport through the blend between the electrodes. Comparison between the simulated and measured I(t)s resulted in values for charge carrier mobility, average charge velocity and variation of charge velocity. Our results show that the hole mobility in blends is increased by more than an order of magnitude in comparison to the hole mobility of a neat layers of P3HT

  18. Blends of guayule natural rubber latex with commercial latex polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum) is a woody desert shrub that produces natural rubber, cis-1,4 polyisoprene, by biosynthesis. It is currently cultivated in the southwestern United States as a source of latex and rubber for commercial development. Guayule latex is similar to Hevea latex in polymer mo...

  19. Laser Raman, XRD, DSC and Ac-Impedance Analysis of Polymer Blend Electrolyte Based on Eco-Friendly Pva-Pvp Blend with NH4NO3

    NASA Astrophysics Data System (ADS)

    Rajeswari, N.; Selvasekarapandian, S.; Prabaharan, S. R. S.; Kawamura, J.; Iwai, Y.; Karthikeyan, S.

    2013-07-01

    Proton conducting polymer blend electrolytes have attractive interest because of their advantages such as processability, flexibility, electrochemical stability, easy handling and their applications to a variety of electrochemical devices such as fuel cells, chemical sensor and electrochemical displays. In the present work, the films of 50PVA-50PVP blend with different MWt% concentrations of NH4NO3 have been prepared by solution casting techniques using distilled water as a solvent. The prepared films have been investigated by different techniques such as XRD, DSC, Laser Raman and AC Impedance spectroscopy. XRD studies reveal the amorphous nature of the polymer blend-salt complexes. The glass transition temperature has been calculated from the DSC analysis. From the AC Impedance spectroscopy, the high conductivity of the 30MWt% of NH4NO3 doped 50PVA-50PVP polymer complex has been found to be the order of 1.41 × 10-3S cm-1 at room temperature.

  20. Mechanical properties of melt-processed polymer blend of amorphous corn flour composite filler and styrene-butadiene rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The corn flour composite fillers were prepared by blending corn flour with rubber latex, dried, and cryogenically ground into powders, which were then melt-blended with rubber polymers in an internal mixer to form composites with enhanced mechanical properties. The composites prepared with melt-blen...

  1. Ultra-Flexible, Invisible Thin-Film Transistors Enabled by Amorphous Metal Oxide/Polymer Channel Layer Blends

    DTIC Science & Technology

    2015-02-25

    Transistors Enabled by Amorphous Metal Oxide/Polymer Channel Layer Blends Xinge Yu , Li Zeng , Nanjia Zhou , Peijun Guo , Fengyuan Shi , Donald B...chemical vapor deposition processes. Thus, a key issue for inexpensive large-scale roll-to-roll production is to enable MO TFT manu- facturing with...4. TITLE AND SUBTITLE Ultra-Flexible, ’Invisible’ Thin-Film Transistors Enabled by Amorphous Metal Oxide/Polymer Channel Layer Blends 5a. CONTRACT

  2. On the energetic dependence of charge separation in low-band-gap polymer/fullerene blends.

    PubMed

    Dimitrov, Stoichko D; Bakulin, Artem A; Nielsen, Christian B; Schroeder, Bob C; Du, Junping; Bronstein, Hugo; McCulloch, Iain; Friend, Richard H; Durrant, James R

    2012-11-07

    The energetic driving force required to drive charge separation across donor/acceptor heterojunctions is a key consideration for organic optoelectronic devices. Herein we report a series of transient absorption and photocurrent experiments as a function of excitation wavelength and temperature for two low-band-gap polymer/fullerene blends to study the mechanism of charge separation at the donor/acceptor interface. For the blend that exhibits the smallest donor/acceptor LUMO energy level offset, the photocurrent quantum yield falls as the photon excitation energy is reduced toward the band gap, but the yield of bound, interfacial charge transfer states rises. This interplay between bound and free charge generation as a function of initial exciton energy provides key evidence for the role of excess energy in driving charge separation of direct relevance to the development of low-band-gap polymers for enhanced solar light harvesting.

  3. A Solution-Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics.

    PubMed

    Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy-Quiles, Mariano; Müller, Christian

    2017-01-01

    Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution-doped conjugated polymer poly(3-hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer-thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm(-1) and Seebeck coefficient from 100 to 60 μV K(-1) upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m(-1) K(-1) gives rise to a thermoelectric Figure of merit ZT ∼ 10(-4) that remains unaltered for an insulator content of more than 60 wt%. Free-standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends.

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

    PubMed

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

    2017-01-25

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

  5. Novel polymer blends for the preparation of membranes for biohybrid liver systems.

    PubMed

    Kostadinova, Aneliya; Seifert, Barbara; Albrecht, Wolfgang; Malsch, Guenter; Groth, Thomas; Lendlein, Andreas; Altankov, George

    2009-01-01

    It was found previously that membranes based on co-polymers of acrylonitrile (AN) and 2-acrylamido-2-methyl-propansulfonic acid (AMPS) greatly stimulated the functionality and survival of primary hepatocytes. In those studies, however, the pure AN-AMPS co-polymer had poor membrane-forming properties, resulting in quite dense rubber-like membranes. Hence, membranes with required permeability and optimal biocompatibility were obtained by blending the AN-AMPS co-polymer with poly(acrylonitrile) homopolymer (PAN). The amount of PAN (P) and AN-AMPS (A) in the blend was varied from pure PAN (P/A-100/0) over P/A-75/25 and P/A-50/50 to pure AN-AMPS co-polymer (P/A-0/100). A gradual decrease of molecular cut-off of membranes with increase of AMPS concentration was found, which allows tailoring membrane permeability as necessary. C3A hepatoblastoma cells were applied as a widely accepted cellular model for assessment of hepatocyte behaviour by attachment, viability, growth and metabolic activity. It was found that the blend P/A-50/50, which possessed an optimal permeability for biohybrid liver systems, supported also the attachment, growth and function of C3A cells in terms of fibronectin synthesis and P-450 isoenzyme activity. Hence, blend membranes based on a one to one mixture of PAN and AN-AMPS combine sufficient permeability with the desired cellular compatibility for application in bioreactors for liver replacement.

  6. The Effect of Difunctional Oligomer Concentration and Processing Temperature on the Reactive Processing of Polymer Blends

    NASA Astrophysics Data System (ADS)

    O'Brien, Charles; Rice, Kevin; Dadmun, Mark

    2001-03-01

    Reactive processing is an interesting method to form compatibilizers for polymer blends in-situ. A model blend composed of poly(bisphenol A-co-epichlorohydrin) and poly(ethylene oxide) that is compatibilized with difunctional oligomers that are the same structure as the homopolymers is currently under investigation. It is expected that blocky copolymers will form at the bipahasic interface during processing as the difunctional oligomers undergo an addition copolymerization. Previous results have shown that the addition of the reactive oligomers improves the properties of the blend and thus this reactive process scheme is feasible. Additionally, these results indicate that the difunctioanal oligomers may act as plasticizers and continue to polymerize at room temperature after the blend is removed from the melt mixer. In this presentation, we will discuss our research that is focused on optimizing the reactive compatibilization process by controlling the amount of reactive oligomer added and the processing temperature and evaluating the effect of these parameters on the ultimate properties of the blend.

  7. High-performance all-polymer solar cells via side-chain engineering of the polymer acceptor: the importance of the polymer packing structure and the nanoscale blend morphology.

    PubMed

    Lee, Changyeon; Kang, Hyunbum; Lee, Wonho; Kim, Taesu; Kim, Ki-Hyun; Woo, Han Young; Wang, Cheng; Kim, Bumjoon J

    2015-04-17

    The effectiveness of side-chain engineering is demonstrated to produce highly efficient all-polymer solar cells (efficiency of 5.96%) using a series of naphthalene diimide-based polymer acceptors with controlled side chains. The dramatic changes in the polymer packing, blend morphology, and electron mobility of all-polymer solar cells elucidate clear trends in the photovoltaic performances.

  8. Influence of annealing and blending of photoactive polymers on their crystalline structure.

    PubMed

    Ruderer, Matthias A; Prams, Stefan M; Rawolle, Monika; Zhong, Qi; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter

    2010-12-02

    Thin photoactive polymer films of poly(3-octylthiophene-2,5-diyl) (P3OT) and poly(2,5-di(hexyloxy)cyanoterephthalylidene) (CN-PPV) are investigated. With X-ray reflectivity measurements, a linear concentration-thickness dependence is found for both polymers and the molecular weight of CN-PPV is determined from this concentration-thickness dependence. Based on the molecular weights, the critical blending ratio is determined. Grazing incidence wide-angle X-ray scattering (GIWAXS) is used to probe the crystallinity of thin films and to determine characteristic length scales of the crystalline structure. Moreover, the orientation of the crystalline parts regarding the substrate of both the homopolymer and the blended films is probed with GIWAXS. Temperature annealing is found to improve the crystallization for both homopolymers. In addition, reorientation of the predominant crystalline structures takes place. Blending both polymers reduces or even suppresses the crystallization during spin coating as well as temperature annealing. Absorption measurements complement the structural investigations.

  9. Mode-of-Action of Self-Extinguishing Polymer Blends Containing Organoclays

    SciTech Connect

    Pack, S.; Si, M; Koo, J; Sokolov, J; Koga, T; Kashiwagi, T; Rafailovich, M

    2009-01-01

    We have shown that the addition of nanoclays is an effective means for enhancing the flame retardant properties of polymer blends. Polymer blends are difficult to render flame retardant even with the addition of flame retardant agents due to dispersion and phase segregation during the heating process. We show that the addition of 5% functionalized Cloisite 20A clays in combination with 15% decabromodiphenyl ether and 4% antimony trioxide to a polystyrene/poly(methyl methacrylate) blend can render the compound flame resistant within the UL-94-V0 standard. Using a variety of micro-characterization methods, we show that the clays are concentrated at the interfaces between the polymers in this blend and completely suppress phase segregation. The flame retardant (FR) is absorbed onto the clay surfaces, and the exfoliation of the clays also distributes the FR agent uniformly within the matrix. TGA of the nanocomposite indicates that prior to the addition of clay, the dissociation times of the individual components varied by more than 20 C, which complicated the gas-phase kinetics. Addition of the clays causes all the components to have a single dissociation temperature, which enhanced the efficacy of the FR formula in the gas phase. Cone calorimetry also indicated that the clays decreased the heat release rate (HRR) and the mass loss rate (MLR), due to the formation of a robust char. In contrast, minimal charring occurred in blends containing just the FR. SEM examination of the chars showed that the clay platelets were curved and in some cases tightly folded into nanotube-like structures. These features were only apparent in blends, indicating that they might be associated with thermal gradients across the polymer phase interface. SEM and SAXS examinations of the nanocomposites after partial exposure to the flame indicated that the clays aggregated into ribbon-like structures, approximately microns in length, after the surfactant thermally decomposed. Thermal modeling

  10. Polymer blend particles with defined compositions for targeting antigen to both class I and II antigen presentation pathways.

    PubMed

    Tran, Kenny K; Zhan, Xi; Shen, Hong

    2014-05-01

    Defense against many persistent and difficult-to-treat diseases requires a combination of humoral, CD4(+) , and CD8(+) T-cell responses, which necessitates targeting antigens to both class I and II antigen presentation pathways. In this study, polymer blend particles are developed by mixing two functionally unique polymers, poly(lactide-co-glycolide) (PLGA) and a pH-responsive polymer, poly(dimethylaminoethyl methacrylate-co-propylacrylic acid-co-butyl methacrylate) (DMAEMA-co-PAA-co-BMA). Polymer blend particles are shown to enable the delivery of antigens into both class I and II antigen presentation pathways in vitro. Increasing the ratio of the pH-responsive polymer in blend particles increases the degree of class I antigen presentation, while maintaining high levels of class II antigen presentation. In a mouse model, it is demonstrated that a significantly higher and sustained level of CD4(+) and CD8(+) T-cell responses, and comparable antibody responses, are elicited with polymer blend particles than PLGA particles and a conventional vaccine, Alum. The polymer blend particles offer a potential vaccine delivery platform to generate a combination of humoral and cell-mediated immune responses that insure robust and long-lasting immunity against many infectious diseases and cancers.

  11. Substrats poreux biodegradables prepares a partir de phases co-continues dans les melanges de polymeres immiscibles

    NASA Astrophysics Data System (ADS)

    Sarazin, Pierre

    2003-06-01

    In this thesis a novel approach to preparing biodegradable materials with highly structured and interconnected porosity is proposed. The method involves the controlled preparation of immiscible co-continuous polymer blends using melt-processing technology followed by a bulk solvent extraction step of one of the phases (the porogen phase). A co-continuous structure is defined as the state when each phase of the blend is fully interconnected through a continuous pathway. This method allows for the preparation of porous materials with highly controlled pore size, pore volume and pore shape which can then be transformed and shaped in various forms useful for biomedical applications. Various properties of the skin of the polymeric articles (closed-cell, open-cell, modification of the pore size) can be controlled. Initially, the study on the immiscible binary and compatibilized poly(L-lactide)/polystyrene blends (PLLA/PS) after extraction of the PS phase demonstrated that highly percolated blends exist from 40--75%PS and 40--60%PS for the binary and compatibilized blends, respectively. It is demonstrated that both the pore size and extent of co-continuity can be controlled through composition and interfacial modification. The subsequent part of our work treats of the preparation of porous PLLA from a blend of two biodegradable polymers and the performance of such porous materials. This portion of the work uses only polymer materials which have been medically approved for internal use. In this case, small amounts of the porogen phase can be tolerated in the final porous substrate. Co-continuous blends comprised of poly(L-lactide)/Poly(epsilon-caprolactone) PLLA/PCL, were prepared via melt processing. A wide range of phase sizes for the co-continuous blend is generated through a combination of concentration control and quiescent annealing. As the PLLA phase can not be dissolved selectively in PLLA/PS blends, the co-continuity range was evaluated indirectly. To precisely

  12. Renormalized one-loop theory of correlations in polymer blends.

    PubMed

    Qin, Jian; Morse, David C

    2009-06-14

    The renormalized one-loop theory is a coarse-grained theory of corrections to the random phase approximation (RPA) theory of composition fluctuations. We present predictions of corrections to the RPA for the structure function S(k) and to the random walk model of single-chain statics in binary homopolymer blends. We consider an apparent interaction parameter chi(a) that is defined by applying the RPA to the small k limit of S(k). The predicted deviation of chi(a) from its long chain limit is proportional to N(-1/2), where N is the chain length. This deviation is positive (i.e., destabilizing) for weakly nonideal mixtures, with chi(a)N less than or approximately 1, but negative (stabilizing) near the critical point. The positive correction to chi(a) for low values of chi(a)N is a result of the fact that monomers in mixtures of shorter chains are slightly less strongly shielded from intermolecular contacts. The predicted depression in chi(a) near the critical point is a result of long-wavelength composition fluctuations. The one-loop theory predicts a shift in the critical temperature of O(N(-1/2)), which is much greater than the predicted O(N(-1)) width of the Ginzburg region. Chain dimensions are found to deviate slightly from those of a random walk even in a one-component melt and contract slightly as thermodynamic repulsion is increased. Predictions for S(k) and single-chain properties are compared to published lattice Monte Carlo simulations.

  13. Exciton diffusion and dissociation in conjugated polymer/fullerene blends and heterostructures

    NASA Astrophysics Data System (ADS)

    Haugeneder, A.; Neges, M.; Kallinger, C.; Spirkl, W.; Lemmer, U.; Feldmann, J.; Scherf, U.; Harth, E.; Gügel, A.; Müllen, K.

    1999-06-01

    We investigate the exciton dynamics in composite systems of conjugated polymers and fullerene molecules by photoluminescence (PL) and femtosecond transient absorption experiments. In solid mixtures (blends) we find a strong concentration-dependent quenching of the polymer PL. This is attributed to an efficient electron transfer (ET) from the photoexcited conjugated polymer to the fullerene. The ET dynamics is directly monitored by measuring the transient stimulated emission of the conjugated polymer. The transfer rate depends linearly on the C60 concentration and ranges between (66 ps)-1 and (5 ps)-1 for concentrations from 0.5% to 5%. This dependence is in accordance with an exciton diffusion process occurring prior to the ET. The exciton diffusion length in the conjugated polymer is directly determined by measuring the PL quenching in well-defined heterostructures comprising a self-assembled fullerene monolayer and a thin spin-coated polymer layer of variable thickness. From these measurements we infer a value of 14 nm for the exciton diffusion length in ladder-type poly (p-phenylene). Our results are of direct relevance for further optimization of polymer photovoltaic devices.

  14. Formation of anisotropic polymer blend by photopolymerization of lyotropic LC-phase

    NASA Astrophysics Data System (ADS)

    Wojciechowski, Piotr; Ulanski, J.; Kryszewski, Marian; Okrasa, Lidia; Czajkowski, Wojciech

    1995-08-01

    The structural characteristics are given for the polymer blend (PB) prepared by photopolymerization of the uniaxially oriented liquid crystal (LC)-phase of the hydroxypropylcellulose-acrylic acid (HPC-AA) system. The uniaxially oriented films of HPC- AA mesophase show a so-called banded structure under cross polarizers, characteristic for uniaxially oriented LC-polymer films. The state of order of HPC-AA mesophase was investigated by effect of dye orientation in LC-media. The influence of the length of the cholesteric pitch of HPC-AA on the order parameter of dye was found. The polymer blend as a product of the photopolymerization of AA in the lyotropic and uniaxially oriented medium HPC-AA is a birefringent solid system, was strongly affected by crosslinking processes. The PB has a LC-organization up to thermal decomposition at 230 degrees C, as shown by TOA and microscopic observations. The PB can be regarded as a new kind of the thermally resistant LC-polymer network.

  15. High loading fragrance encapsulation based on a polymer-blend: preparation and release behavior.

    PubMed

    Sansukcharearnpon, Aurapan; Wanichwecharungruang, Supason; Leepipatpaiboon, Natchanun; Kerdcharoen, Teerakiat; Arayachukeat, Sunatda

    2010-05-31

    The six fragrances, camphor, citronellal, eucalyptol, limonene, menthol and 4-tert-butylcyclohexyl acetate, which represent different chemical functionalities, were encapsulated with a polymer-blend of ethylcellulose (EC), hydroxypropyl methylcellulose (HPMC) and poly(vinyl alcohol) (PV(OH)) using solvent displacement (ethanol displaced by water). The process gave >or=40% fragrance loading capacity with >or=80% encapsulation efficiency at the fragrance to polymer weight ratio of 1:1 and at initial polymer concentrations of 2000-16,000 ppm and the obtained fragrance-encapsulated spheres showed hydrodynamic diameters of less than 450 nm. The release profile of the encapsulated fragrances, evaluated by both thermal gravimetric and electronic nose techniques, indicated different release characteristics amongst the six encapsulated fragrances. Limonene showed the fastest release with essentially no retention by the nanoparticles, while eucalyptol and menthol showed the slowest release.

  16. Switching phase separation mode by varying the hydrophobicity of polymer additives in solution-processed semiconducting small-molecule/polymer blends

    NASA Astrophysics Data System (ADS)

    He, Zhengran; Li, Dawen; Hensley, Dale K.; Rondinone, Adam J.; Chen, Jihua

    2013-09-01

    Lateral and vertical phase separations play critical roles in the performance of the next-generation organic and hybrid electronic devices. A method is demonstrated here to switch between lateral and vertical phase separations in semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPSE pentacene)/polymer blend films by simply varying the alkyl length of the polyacrylate polymer component. The phase separation modes depend on intermolecular interactions between small molecule TIPSE pentancene and polymer additives. The blend film with a dominant vertical phase separation exhibits a significant enhancement in average mobility and performance consistency of organic thin-film transistors.

  17. Kinetics of Microphase Separation in Crosslinked Polymer Blend

    SciTech Connect

    Bettachy, A.; Benhamou, M.; Derouiche, A.; Fazni, A.

    2009-04-19

    The solvent effect on the early kinetics of the microphase separation (MPS) in binary crosslinked polymer was studied. In the presence of a good solvent, calculations were done using first the random phase approximation method and second an extended blob model, where a crosslinked chain is viewed as a sequence having blobs as new units. Kinetics were studied through the variation of the relaxation rate, {tau}{sub q}, upon the wave number, q, in the region around the spinodal temperature. When the temperature is changed from an initial value, T{sub i}, toward the final value, T{sub f}, very close to the critical point, the only motion allowed to the crosslinked chains is of Rouse type because of the presence of the crosslinks. The swelling effect on the MPS leads to a multiplicative renormalization of critical parameters of the molten state by factors as power of the overall monomer volume fraction, {phi}. The characteristic frequency, {omega}{sub (q)}, inverse of {tau}{sub q}, scales as {omega}(q) congruent with q{sup 6}{epsilon}{sup 3}, where {epsilon} stands for the traditional screening length. The study of kinetics of MPS is then extended in the presence of a theta solvent.

  18. Formulation and evaluation of atenolol floating bioadhesive system using optimized polymer blends

    PubMed Central

    Siddam, Haritha; Kotla, Niranjan G.; Maddiboyina, Balaji; Singh, Sima; Sunnapu, Omprakash; Kumar, Anil; Sharma, Dinesh

    2016-01-01

    Introduction: Oral sustained release gastro retentive dosage forms offer several advantages for drugs having absorption from the upper gastrointestinal tract to improve the bioavailability of medications which have narrow absorption window. The aim of the study was to develop a floating bioadhesive drug delivery system exhibiting a unique combination of floatation and bioadhesion to prolong the residence in the stomach using atenolol as a model drug. Methods: Prior to compression, polymeric blend(s) were evaluated for flow properties. The tablets were prepared by direct compression method using bioadhesive polymer like Carbopol 934P and hydrophilic polymers like HPMC K4M, HPMC K15M, and HPMC K100M. The prepared tablets were evaluated for physical characteristics, bioadhesive strength, buoyancy lag time, swelling index and in vitro drug release studies. Results: The mean bioadhesive strength was found to be in the range of 16.2 to 52.1 gm. The optimized blend (F11) showed 92.3% drug releases after 24 hrs. Whilst, increase in concentration of carbopol 934P, bioadhesive strength and swelling index was increased with slow release. The n values of optimized formulations were found in the range of 0.631-0.719 indicating non-fickian anomalous type transport mechanism. Conclusion: The study aided in developing an ideal once-a-day gastro retentive floating drug delivery system with improved floating, swelling and bioadhesive characteristics with better bioavailability. PMID:27051631

  19. RELEASE AND MUCOADHESION PROPERTIES OF DICLOFENAC MATRIX TABLETS FROM NATURAL AND SYNTHETIC POLYMER BLENDS.

    PubMed

    Odeniyi, Michael A; Khan, Nasir H; Peh, Kok K

    2015-01-01

    The delayed release and mucoadhesive properties of Cedrela gum and hydroxypropylmethylcellulose blend in diclofenac sodium tablet formulations were evaluated. Tablets were prepared by direct compression and the crushing strength and detachment force were found to increase from 74.49 ± 1.22 to 147.25 ± 2.57 N and 0.302 ± 0.36 to 1.141 ± 0.05 N from low to high level of polymers, respectively. The release kinetics followed Korsmeyer-Peppas release and the n varied between 0.834 and 1.273, indicating that the release mechanism shifts from Fickian to super case I (anomalous release). The drug release profile fits a pulsatile-release pattern characterized by a lag time followed by a more or less rapid and complete drug release. The Cedrela gum-hydroxypropylmethylcelluse blend tablets delayed diclofenac release for 2 h and sustained the release for 12 h. The polymer blend delayed drug release in the 0.1 M HCl simulating gastric environment and subsequent release pH 6.8 phosphate buffer.

  20. Development of a Chemiresistor Sensor Based on Polymers-Dye Blend for Detection of Ethanol Vapor

    PubMed Central

    dos Reis, Marcos A. L.; Thomazi, Fabiano; Nero, Jordan Del; Roman, Lucimara S.

    2010-01-01

    The conductive blend of the poly (3,4-ethylene dioxythiophene) and polystyrene sulfonated acid (PEDOT-PSS) polymers were doped with Methyl Red (MR) dye in the acid form and were used as the basis for a chemiresistor sensor for detection of ethanol vapor. This Au | Polymers-dye blend | Au device was manufactured by chemical vapor deposition and spin-coating, the first for deposition of the metal electrodes onto a glass substrate, and the second for preparation of the organic thin film forming ∼1.0 mm2 of active area. The results obtained are the following: (i) electrical resistance dependence with atmospheres containing ethanol vapor carried by nitrogen gas and humidity; (ii) sensitivity at 1.15 for limit detection of 26.25 ppm analyte and an operating temperature of 25 °C; and (iii) the sensing process is quickly reversible and shows very a low power consumption of 20 μW. The thin film morphology of ∼200 nm thickness was analyzed by Atomic Force Microscopy (AFM), where it was observed to have a peculiarly granulometric surface favorable to adsorption. This work indicates that PEDOT-PSS doped with MR dye to compose blend film shows good performance like resistive sensor. PMID:22319273

  1. In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating.

    PubMed

    Ebbens, Stephen; Hodgkinson, Richard; Parnell, Andrew J; Dunbar, Alan; Martin, Simon J; Topham, Paul D; Clarke, Nigel; Howse, Jonathan R

    2011-06-28

    Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. Applications for such layers include photovoltaics and light-emitting diodes where performance relies upon the nanoscale phase separation morphology of the spun film. Furthermore, at micrometer scales, phase separation provides a route to produce self-organized structures for templating applications. Understanding the factors that determine the final phase-separated morphology in these systems is consequently an important goal. However, it has to date proved problematic to fully test theoretical models for phase separation during spin coating, due to the high spin speeds, which has limited the spatial resolution of experimental data obtained during the coating process. Without this fundamental understanding, production of optimized micro- and nanoscale structures is hampered. Here, we have employed synchronized stroboscopic illumination together with the high light gathering sensitivity of an electron-multiplying charge-coupled device camera to optically observe structure evolution in such blends during spin coating. Furthermore the use of monochromatic illumination has allowed interference reconstruction of three-dimensional topographies of the spin-coated film as it dries and phase separates with nanometer precision. We have used this new method to directly observe the phase separation process during spinning for a polymer blend (PS-PI) for the first time, providing new insights into the spin-coating process and opening up a route to understand and control phase separation structures.

  2. Ultrafast charge- and energy-transfer dynamics in conjugated polymer: cadmium selenide nanocrystal blends.

    PubMed

    Morgenstern, Frederik S F; Rao, Akshay; Böhm, Marcus L; Kist, René J P; Vaynzof, Yana; Greenham, Neil C

    2014-02-25

    Hybrid nanocrystal-polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer-nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic-nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends.

  3. A blended polymer electret-based micro-electronic power generator

    NASA Astrophysics Data System (ADS)

    Ko, Wen-Ching; Lee, Bor-Shiun; Chen, Jia-Lun; Lin, Shun-Chi; Wu, Wen-Jong; Lee, Chih-Kung

    2008-03-01

    Recently, power harvesting technologies for low-power electronic devices have attracted much interest. In this paper, the design and fabrication methods of a micro-electrostatic power generator is presented. This power generator comprises a stator developed using an electret film for charge storage and a rotor covered by an interdigital electrode for electric power generation. The newly developed electret material is made from mixing two solutions. The first solution was made by blending polystyrene (PS) and cycloolefin copolymer (COC). The second solution was obtained by an additive process as polar molecule was added into COC. This unique two solution electret method can easily be integrated and adopted to the micro fabrication process. The charge storage capability of this new electret material was investigated and results showed that low concentration of polystyrene in the blended material will not only have more stable but also higher electrostatic charge than that of pure COC. In addition, the polar molecular additives also improve the electret properties of COC due to micro-cavities formation and the interactions between molecules and polymer. Our newly developed blended electret material has excellent mechanical properties and is easy to use when compared to using Teflon Fluorinated Ethylene Propylene (FEP) and polypropylene (PP). A feasibility study of a micro electrostatic power generator based on our blended electret material was performed. Experimental results demonstrate the feasibility and effectiveness of this new type of micro electrostatic power generator.

  4. Cellulose acetate hollow fiber membranes blended with phospholipid polymer and their performance for hemopurification.

    PubMed

    Ye, Sang Ho; Watanabe, Junji; Ishihara, Kazuhiko

    2004-01-01

    Commercially available hollow fiber membranes (HFMs) made from synthetic polymers, including cellulose acetate (CA) HFMs, used as hemopurification membranes, need to improve in hemocompatibility, by suppressing protein adsorption and clot formation. In this study, CA HFMs blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer (PMB30 composed of MPC and n-butyl methacrylate (BMA)) were prepared by a dry-jet wet spinning process. Their performances were evaluated by characterizing their properties such as structure, permeability and protein adsorption. CA/PMB30-blend HFMs showed structure changes such as increase of porosity, development of large pores and decreasing of the thickness of the active layer. And the structure and permeability of CA/PMB30-blend HFMs were controllable by changing preparation conditions. Also, the CA/PMB30-blend HFMs had good permeability, low protein adsorption and low fouling property during the permeability experiment in comparison with CA HFMs, because the hydrophilic and hemocompatible MPC copolymer (PMB30) existed on the surface of the HFM.

  5. Chain conformation-dependent thermal conductivity of amorphous polymer blends: the impact of inter- and intra-chain interactions.

    PubMed

    Wei, Xingfei; Zhang, Teng; Luo, Tengfei

    2016-11-30

    Polymers with high thermal conductivities are of great interest for both scientific research and industrial applications. In this study, model amorphous polymer blends are studied using molecular dynamics simulations. We have examined the effects of inter- and intra-chain interactions on the molecular-level conformations of the blends, which in turn impact their thermal conductivity. It is found that the thermal conductivity of polymer blends is strongly related to the molecular conformation, especially the spatial extent of the molecular chains indicated by their radius of gyration. Tuning the intra-chain van der Waals (vdW) interaction leads to different molecular structures of the minor component in the binary blend, but the thermal conductivity is not changed. However, increasing the inter-chain vdW interactions between the major and the minor components will increase the thermal conductivity of the blend, which is due to the conformation change in the major component that leads to enhanced thermal transport along the chain backbone through the intra-chain bonding interactions. The fundamental structure-property relationship from this study may provide useful guidance for designing and synthesizing polymer blends with desirable thermal conductivity.

  6. Microstructural and electrical properties of PVA/PVP polymer blend films doped with cupric sulphate

    NASA Astrophysics Data System (ADS)

    Hemalatha, K.; Mahadevaiah, Gowtham, G. K.; Urs, G. Thejas; Somashekarappa, H.; Somashekar, R.

    2016-05-01

    A series of polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) polymer blends added with different concentrations of cupric sulphate (CuSO4) were prepared by solution casting method and were subjected to X-ray diffraction (XRD) and Ac conductance measurements. An attempt has been made to study the changes in crystal imperfection parameters in PVA/PVP blend films with the increase in concentration of CuSO4. Results show that decrease in micro crystalline parameter values is accompanied with increase in the amorphous content in the film which is the reason for film to have more flexibility, biodegradability and good ionic conductivity. AC conductance measurements in these films show that the conductivity increases as the concentration of CuSO4 increases. These films were suitable for electro chemical applications.

  7. Phase separation dynamics in polymer blends close to Tg: aging and rejuvenating

    NASA Astrophysics Data System (ADS)

    Julien, Gregoire

    2013-03-01

    We extend the Percolation of Free Volume Distribution (PFVD) model developed by Long and co-workers to deal with polymer blends dynamics close to the glass transition. The dynamical model incorporates an extension of the Flory Huggins model to the case of compressible blends for calculating the driving forces. Spatial dynamics follows then from an Onsager like description. The model is solved on a 2D lattice corresponding to spatial scales of about a few tens to 100 nm and a resolution corresponding to the scale of dynamical heterogeneities, allowing to study phase separation close to Tg. We study also the reverse process, after the temperature is increased again in the totally miscible range. We observe a temporal asymmetry between the aging and the rejuvenation dynamics: the slow domains melt much faster than the elapsed time required to built them during the separation process and total miscibility is recovered after a much shorter time.

  8. Light-scattering thermal cross-linking material using morphology of nanoparticle free polymer blends

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi

    2015-03-01

    A newly light-scattering thermal cross-linking material based on self-assembly for forming the morphology of nanoparticle free polymer blends was reported. The material design concept to use light-scattering thermal cross-linking material with high uniformity of light on display panel from LED for high quality such as brightness and evenness, mechanical properties, and gas and water barrier properties. The high light scattering rate of 8 % at 350-450 nm of wavelength, fast cure film at 140 ºC and 120 s, and thermal stability at 190 ºC in bake condition for high productivity were indicated in the light-scattering thermal cross-linking material using the nanoparticle free polymers with carboxylic acid functional groups. These novel system using morphology of nanoparticle free polymer blends in light-scattering package material for a LCD using LED was a valuable approach to the design of material formulations for newly light-scattering thermal cross-linking material.

  9. Temperature and composition-dependent density of states in organic small-molecule/polymer blend transistors

    NASA Astrophysics Data System (ADS)

    Hunter, Simon; Mottram, Alexander D.; Anthopoulos, Thomas D.

    2016-07-01

    The density of trap states (DOS) in organic p-type transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES ADT), the polymer poly(triarylamine) and blends thereof are investigated. The DOS in these devices are measured as a function of semiconductor composition and operating temperature. We show that increasing operating temperature causes a broadening of the DOS below 250 K. Characteristic trap depths of ˜15 meV are measured at 100 K, increasing to between 20 and 50 meV at room-temperature, dependent on the semiconductor composition. Semiconductor films with high concentrations of diF-TES ADT exhibit both a greater density of trap states as well as broader DOS distributions when measured at room-temperature. These results shed light on the underlying charge transport mechanisms in organic blend semiconductors and the apparent freezing-out of hole conduction through the polymer and mixed polymer/small molecule phases at temperatures below 225 K.

  10. Effects of attractive colloids on the phase separation behaviors of binary polymer blends

    NASA Astrophysics Data System (ADS)

    Zhang, Xinghua; Chen, Yunlin; Qu, Lijian; Yan, Dadong

    2013-08-01

    The attractive colloids are added as fillers to control the phase behaviors of binary polymer blends. Because the colloids attract both components in the blends, aggregates are formed by the colloids coated with both kinds of polymer brushes. The aggregation results in two contradictory effects on the phase separation. First, the formation of aggregate decreases the translational entropy, which promotes the phase separation. On the other hand, the phase separation causes the extra free energy penalty due to the stretch of the chains attaching on the colloids, which prevents the phase separation. Furthermore, as the concentration or adsorbability of the colloids increases the local fluctuations within the aggregates become important. This results in a transition from the macro-phase separation to the micro-phase separation and the existence of the Lifshitz point. All of these effects lead to diverse phase behaviors in the polymer nanocomposites system. In present work, these behaviors are studied theoretically by the random phase approximation in a model system.

  11. Broadband ultrafast photoluminescence spectroscopy resolves charge photogeneration via delocalized hot excitons in polymer:fullerene photovoltaic blends.

    PubMed

    Chen, Kai; Barker, Alex J; Reish, Matthew E; Gordon, Keith C; Hodgkiss, Justin M

    2013-12-11

    Conventional descriptions of excitons in semiconducting polymers do not account for several important observations in polymer:fullerene photovoltaic blends, including the ultrafast time scale of charge photogeneration in phase separated blends and the intermediate role of delocalized charge transfer states. We investigate the nature of excitons in thin films of polymers and polymer:fullerene blends by using broadband ultrafast photoluminescence spectroscopy. Our technique enables us to resolve energetic relaxation, as well as the volume of excitons and population dynamics on ultrafast time scales. We resolve substantial high-energy emission from hot excitons prior to energetic relaxation, which occurs predominantly on a subpicosecond time scale. Consistent with quantum chemical calculations, ultrafast annihilation measurements show that excitons initially extend along a substantial chain length prior to localization induced by structural relaxation. Moreover, we see that hot excitons are initially highly mobile and the subsequent rapid decay in mobility is correlated with energetic relaxation. The relevance of these measurements to charge photogeneration is confirmed by our measurements in blends. We find that charge photogeneration occurs predominately via these delocalized hot exciton states in competition with relaxation and independently of temperature. As well as accounting for the ultrafast time scale of charge generation across large polymer phases, delocalized hot excitons may also account for the crucial requirement that primary charge pairs are well separated in efficient organic photovoltaic blends.

  12. Dispersion states and surface characteristics of physically blended polyhedral oligomeric silsesquioxane/polymer hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    Misra, Rahul

    Control of dispersion and segregation states of nanostructured additives is one of the biggest challenges in realizing the optimum potential of high performance hybrid polymer nanocomposites. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, with their hybrid organic-inorganic nature and flexible functionalization with a variety of organic substituents, yield possibilities to control dispersion and tune compatibility in a wide range of polymer systems. The overall goal of this research is to investigate the fundamental parameters that influence the dispersion and segregation states of POSS nanostructured chemicals, and to understand chain dynamics and conformations in physically blended POSS hybrid polymer nanocomposites (HPNC's). Multiple structural and mechanical factors influencing macro to nano scale surface and bulk properties were successfully investigated and correlated. A strategy based on thermodynamic principles for selective control of POSS dispersion states in a given polymer matrix is developed and discussed. This dissertation consists of eight chapters. Chapter 1 provides a detailed introduction about the development and current research interest in POSS/polymer nanocomposites. This chapter also discusses limitations of current advanced nanoprobe techniques. Chapter 2 establishes the overall goal of this research and specific research ii objectives. Chapter 3 establishes the preferential surface migration behavior of physically dispersed, non-reactive, closed cage octaisobutyl POSS (Oib-POSS) in a non-polar polypropylene matrix. Furthermore, influence of POSS surface segregation on the surface properties, especially nano-tribomechanical behavior is also discussed. Chapter 4 expands the studies by melt blending two different types of POSS molecules, a non-reactive, closed cage Oib-POSS and an open cage trisilanolphenyl POSS (Tsp-POSS), in a nylon 6 matrix. This chapter discusses the morphology, nano-dispersion and macro- to

  13. Domain Coalescence-Induced Nucleation and Anomalous Growth of Holes in Thin Polymer Blend Film

    NASA Astrophysics Data System (ADS)

    Bi, Wuguo; Yeow, Edwin K. L.

    2011-02-01

    The phase evolution of a thin polymer blend film of polystyrene (PS) and poly(2-vinyl pyridine) (P2VP) triggered by solvent annealing is examined at both the bulk and single-(macro)molecule levels using wide-field microscopy (WFM). The transitions between different evolutionary stages in the nucleation and growth process are clearly visualized in real time and without intermittent breaks. The nucleation of PS holes arises from the coalescence and growth of P2VP domains and the holes expand in a complex manner involving the dewetting of PS and the absorption of P2VP domains into the holes.

  14. Structure-Property Relations in Polymer:Fullerene Blends for Organic Solar Cells.

    PubMed

    Banerji, Natalie

    Organic solar cells consist of thin films combining an electron donor (often a conjugated polymer) with an electron acceptor (often a fullerene derivative), in a blend commonly referred to as bulk heterojunction material. Charge separation between the donor and the acceptor leads to the generation of carriers, which can be extracted from photovoltaic devices in the form of photocurrent. The generation mechanism of free, extractable charges has caused a lot of controversial discussion in literature. Our research has shown that all the steps involved in charge generation are strongly dependent on the arrangement of the donor and the acceptor (i.e. the structure) of the bulk heterojunction.

  15. Biodegradable polymer blends based on corn starch and thermoplastic chitosan processed by extrusion.

    PubMed

    Mendes, J F; Paschoalin, R T; Carmona, V B; Sena Neto, Alfredo R; Marques, A C P; Marconcini, J M; Mattoso, L H C; Medeiros, E S; Oliveira, J E

    2016-02-10

    Blends of thermoplastic cornstarch (TPS) and chitosan (TPC) were obtained by melt extrusion. The effect of TPC incorporation in TPS matrix and polymer interaction on morphology and thermal and mechanical properties were investigated. Possible interactions between the starch molecules and thermoplastic chitosan were assessed by XRD and FTIR techniques. Scanning Electron Microscopy (SEM) analyses showed a homogeneous fracture surface without the presence of starch granules or chitosan aggregates. Although the incorporation of thermoplastic chitosan caused a decrease in both tensile strength and stiffness, films with better extensibility and thermal stability were produced.

  16. Miscibility of poly(lactic acid) and poly(ethylene oxide) solvent polymer blends and nanofibers made by solution blow spinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miscibility of blends of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) was studied in polymer solutions by dilute solution viscometry and in solution blow spun nanofibers by microscopy (SEM, TEM) and by thermal and spectral analysis. Three blends of PLA and PEO were solution blended in...

  17. Shape Memory Polymers from Blends of Elastomers and Crystalline Small Molecules

    NASA Astrophysics Data System (ADS)

    Cavicchi, Kevin; Brostowitz, Nicole; Hukill, Brent; Fairbairn, Heather

    2015-03-01

    This talk will present work on the fabrication of shape memory polymers (SMPs) by swelling natural with molten fatty acids. By this method a SMPs with excellent shape fixity and recovery can be obtained during free recovery after uniaxial deformation to 100% strain. Experiments to measure the shape memory properties under both stress and strain controlled conditions will be reported and compared. This fabrication method offers a number of advantages for preparing SMPs. First, it utilizes natural rubber as the base material for the SMP, which capitalizes on a high performance, commodity elastomer. Second, by blending a commercial polymer with a small molecule additive no additional chemistry is needed for the preparation of the SMP. Third, this route inverts the typically processing steps by crosslinking the permanent network prior to formation of the physically crosslinked reversible network. This offers a means to potentially generate a SMP from any preformed elastomeric article.

  18. Surface-induced phase behavior of polymer/nanoparticle blends with attractions.

    PubMed

    Frischknecht, Amalie L; Padmanabhan, Venkat; Mackay, Michael E

    2012-04-28

    In an athermal blend of nanoparticles and homopolymer near a hard wall, there is a first order phase transition in which the nanoparticles segregate to the wall and form a densely packed monolayer above a certain nanoparticle density. Previous investigations of this phase transition employed a fluids density functional theory (DFT) at constant packing fraction. Here we report further DFT calculations to probe the robustness of this phase transition. We find that the phase transition also occurs in athermal systems at constant pressure, the more natural experimental condition than constant packing fraction. Adding nanoparticle-polymer attractions increases the nanoparticle transition density, while sufficiently strong attractions suppress the first-order transition entirely. In this case the systems display a continuous transition to a bulk layered state. Adding attractions between the polymers and the wall has a similar effect of delaying and then suppressing the first-order nanoparticle segregation transition, but does not lead to any continuous phase transitions.

  19. Ultrafast Charge- and Energy-Transfer Dynamics in Conjugated Polymer: Cadmium Selenide Nanocrystal Blends

    PubMed Central

    2014-01-01

    Hybrid nanocrystal–polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer–nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic–nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends. PMID:24490650

  20. Dispersive Non-Geminate Recombination in an Amorphous Polymer:Fullerene Blend

    PubMed Central

    Kurpiers, Jona; Neher, Dieter

    2016-01-01

    Recombination of free charge is a key process limiting the performance of solar cells. For low mobility materials, such as organic semiconductors, the kinetics of non-geminate recombination (NGR) is strongly linked to the motion of charges. As these materials possess significant disorder, thermalization of photogenerated carriers in the inhomogeneously broadened density of state distribution is an unavoidable process. Despite its general importance, knowledge about the kinetics of NGR in complete organic solar cells is rather limited. We employ time delayed collection field (TDCF) experiments to study the recombination of photogenerated charge in the high-performance polymer:fullerene blend PCDTBT:PCBM. NGR in the bulk of this amorphous blend is shown to be highly dispersive, with a continuous reduction of the recombination coefficient throughout the entire time scale, until all charge carriers have either been extracted or recombined. Rapid, contact-mediated recombination is identified as an additional loss channel, which, if not properly taken into account, would erroneously suggest a pronounced field dependence of charge generation. These findings are in stark contrast to the results of TDCF experiments on photovoltaic devices made from ordered blends, such as P3HT:PCBM, where non-dispersive recombination was proven to dominate the charge carrier dynamics under application relevant conditions. PMID:27225584

  1. Four shades of brown: tuning of electrochromic polymer blends toward high-contrast eyewear.

    PubMed

    Österholm, Anna M; Shen, D Eric; Kerszulis, Justin A; Bulloch, Rayford H; Kuepfert, Michael; Dyer, Aubrey L; Reynolds, John R

    2015-01-28

    We report a straightforward strategy of accessing a wide variety of colors through simple predictive color mixing of electrochromic polymers (ECPs). We have created a set of brown ECP blends that can be incorporated as the active material in user-controlled electrochromic eyewear. Color mixing of ECPs proceeds in a subtractive fashion, and we acquire various hues of brown through the mixing of cyan and yellow primaries in combination with orange and periwinkle-blue secondary colors. Upon oxidation, all of the created blends exhibit a change in transmittance from ca. 10 to 70% in a few seconds. We demonstrate the attractiveness of these ECP blends as active materials in electrochromic eyewear by assembling user-controlled, high-contrast, fast-switching, and fully solution-processable electrochromic lenses with colorless transmissive states and colored states that correspond to commercially available sunglasses. The lenses were fabricated using a combination of inkjet printing and blade-coating to illustrate the feasibility of using soluble ECPs for high-throughput and large-scale processing.

  2. Dispersive Non-Geminate Recombination in an Amorphous Polymer:Fullerene Blend

    NASA Astrophysics Data System (ADS)

    Kurpiers, Jona; Neher, Dieter

    2016-05-01

    Recombination of free charge is a key process limiting the performance of solar cells. For low mobility materials, such as organic semiconductors, the kinetics of non-geminate recombination (NGR) is strongly linked to the motion of charges. As these materials possess significant disorder, thermalization of photogenerated carriers in the inhomogeneously broadened density of state distribution is an unavoidable process. Despite its general importance, knowledge about the kinetics of NGR in complete organic solar cells is rather limited. We employ time delayed collection field (TDCF) experiments to study the recombination of photogenerated charge in the high-performance polymer:fullerene blend PCDTBT:PCBM. NGR in the bulk of this amorphous blend is shown to be highly dispersive, with a continuous reduction of the recombination coefficient throughout the entire time scale, until all charge carriers have either been extracted or recombined. Rapid, contact-mediated recombination is identified as an additional loss channel, which, if not properly taken into account, would erroneously suggest a pronounced field dependence of charge generation. These findings are in stark contrast to the results of TDCF experiments on photovoltaic devices made from ordered blends, such as P3HT:PCBM, where non-dispersive recombination was proven to dominate the charge carrier dynamics under application relevant conditions.

  3. Physical properties of whey protein--hydroxypropylmethylcellulose blend edible films.

    PubMed

    Brindle, L P; Krochta, J M

    2008-11-01

    The formations of glycerol (Gly)-plasticized whey protein isolate (WPI)-hydroxypropylmethylcellulose (HPMC) films, blended using different combinations and at different conditions, were investigated. The resulting WPI: Gly-HPMC films were analyzed for mechanical properties, oxygen permeability (OP), and water solubility. Differences due to HPMC quantity and blend method were determined via SAS software. While WPI: Gly and HPMC films were transparent, blend films were translucent, indicating some degree of immiscibility and/or WPI-HPMC aggregated domains in the blend films. WPI: Gly-HPMC films were stronger than WPI: Gly films and more flexible and stretchable than HPMC films, with films becoming stiffer, stronger, and less stretchable as the concentration of HPMC increased. However, WPI: Gly-HPMC blended films maintained the same low OP of WPI: Gly films, significantly lower than the OP of HPMC films. Comparison of mechanical properties and OP of films made by heat-denaturing WPI before and after blending with HPMC did not indicate any difference in degree of cross-linking between the methods, while solubility data indicated otherwise. Overall, while adding HPMC to WPI: Gly films had a large effect on the flexibility, strength, stretchability, and water solubility of the film polymeric network, results indicated that HPMC had no effect on OP through the polymer network. WPI-HPMC blend films had a desirable combination of mechanical and oxygen barrier properties, reflecting the combination of hydrogen-bonding, hydrophobic interactions, and disulfide bond cross-linking in the blended polymer network.

  4. Correlations in polymer blends: Simulations, perturbation theory, and coarse-grained theory

    NASA Astrophysics Data System (ADS)

    Chung, Jun Kyung

    A thermodynamic perturbation theory of symmetric polymer blends is developed that properly accounts for the correlation in the spatial arrangement of monomers. By expanding the free energy of mixing in powers of a small parameter alpha which controls the incompatibility of two monomer species, we show that the perturbation theory has the form of the original Flory-Huggins theory, to first order in alpha. However, the lattice coordination number in the original theory is replaced by an effective coordination number. A random walk model for the effective coordination number is found to describe Monte Carlo simulation data very well. We also propose a way to estimate Flory-Huggins chi parameter by extrapolating the perturbation theory to the limit of a hypothetical system of infinitely long chains. The first order perturbation theory yields an accurate estimation of chi to first order in alpha. Going to second order, however, turns out to be more involved and an unambiguous determination of the coefficient of alpha2 term is not possible at the moment. Lastly, we test the predictions of a renormalized one-loop theory of fluctuations using two coarse-grained models of symmetric polymer blends at the critical composition. It is found that the theory accurately describes the correlation effect for relatively small values of chiN. In addition, the universality assumption of coarse-grained models is examined and we find results that are supportive of it.

  5. Magnetic field effects in a polymer/fullerene blend photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Jang, Hyuk-Jae; Basham, James I.; Gundlach, David J.; Richter, Curt A.

    Organic photovoltaic (OPV) systems based on blends of conjugated polymers and fullerene derivatives have shown great promise for low-cost and efficient photovoltaic applications. Recent findings suggest that a weak external magnetic field can disturb the spin configuration of excited states and subsequently change properties of OPV cells such as photocurrent. These changes are referred to as magnetic field effects (MFEs). In order to have a better understanding of the underlying mechanisms responsible for the MFEs in polymer/fullerene blend photovoltaic systems, we fabricated poly-3-hexylthiophene (P3HT):phenyl-C61-butyric acid methyl ester (PC61BM) cells and carried out photovoltaic device performance and impedance spectroscopy measurements with and without an externally applied magnetic field. A significant reduction in short circuit current (JSC) as well as open circuit voltage (VOC) was observed with an applied magnetic field of a 0.1 tesla compared to those measured without a magnetic field under the same intensity of illumination. Impedance spectroscopy data gives insights into the influence of an external magnetic field on charge generation and recombination near normal photovoltaic operating conditions.

  6. A Solution‐Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics

    PubMed Central

    Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy‐Quiles, Mariano

    2016-01-01

    Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution‐doped conjugated polymer poly(3‐hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer‐thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm−1 and Seebeck coefficient from 100 to 60 μV K−1 upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m−1 K−1 gives rise to a thermoelectric Figure of merit ZT ∼ 10−4 that remains unaltered for an insulator content of more than 60 wt%. Free‐standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends. PMID:28105396

  7. Uniform "Patchy" Platelets by Seeded Heteroepitaxial Growth of Crystallizable Polymer Blends in Two Dimensions.

    PubMed

    Nazemi, Ali; He, Xiaoming; MacFarlane, Liam R; Harniman, Robert L; Hsiao, Ming-Siao; Winnik, Mitchell A; Faul, Charl F J; Manners, Ian

    2017-03-29

    Rectangular platelets formed by the self-assembly of block copolymers in selective solvents are of interest for a range of applications. Recently, we showed that the seeded growth of crystallizable blends of a block copolymer and homopolymer yields well-defined, low area dispersity examples of these two-dimensional (2D) structures. The key feature was the use of the same crystallizable polymer segment in the seed and blend components to enable an efficient homoepitaxial growth process. Herein we demonstrate that this 2D crystallization-driven self-assembly approach can be extended to heteroepitaxial growth by the use of different crystallizable polymers with compatible crystal structures. This allows the formation of well-defined "patchy" rectangular platelets and platelet block comicelles with different core chemistries. The use of scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy provided key information on the spatial location of the components in the resulting assemblies and thereby valuable insight into the 2D heteroepitaxial growth process.

  8. Thin-film solid-state proton NMR measurements using a synthetic mica substrate: Polymer blends

    NASA Astrophysics Data System (ADS)

    VanderHart, David L.; Prabhu, Vivek M.; Lavery, Kristopher A.; Dennis, Cindi L.; Rao, Ashwin B.; Lin, Eric K.

    2009-11-01

    Solid-state proton nuclear magnetic resonance (NMR) measurements are performed successfully on polymer blend thin films through the use of synthetic mica as a substrate. When used as a substrate, synthetic fluorophlogopite mica with its proton-free, diamagnetic character, allows for adequate measurement sensitivity while minimally perturbing the proton thin-film spectra, especially relative to more commonly available natural micas. Specifically, we use multiple-pulse techniques in the presence of magic-angle spinning to measure the degree of mixing in two different polymer blend thin films, polystyrene/poly(xylylene ether) and poly(1-methyladamantyl methacrylate) (PMAdMA)/triphenylsulfonium perfluorobutanesulfonate (TPS-PFBS), spin-coated onto mica substrates. Our earlier studies had focused on bulk systems where NMR signals are stronger, but may not be representative of thin films of the same systems that are relevant to many applications such as photoresist formulations in the electronics industry. The superiority of synthetic over natural paramagnetic mica is demonstrated by the maintenance of resolution and spinning sideband intensities (relative to bulk samples) for the synthetic mica samples. In contrast, degraded resolution and large spinning sidebands are shown to typify spectra of the natural mica samples. This approach can be applied to many other proton measurements of solid thin films, thereby greatly extending the types of systems to be investigated. Magnetic susceptibility measurements are also reported for all micas used.

  9. Thin-film solid-state proton NMR measurements using a synthetic mica substrate: polymer blends.

    PubMed

    VanderHart, David L; Prabhu, Vivek M; Lavery, Kristopher A; Dennis, Cindi L; Rao, Ashwin B; Lin, Eric K

    2009-11-01

    Solid-state proton nuclear magnetic resonance (NMR) measurements are performed successfully on polymer blend thin films through the use of synthetic mica as a substrate. When used as a substrate, synthetic fluorophlogopite mica with its proton-free, diamagnetic character, allows for adequate measurement sensitivity while minimally perturbing the proton thin-film spectra, especially relative to more commonly available natural micas. Specifically, we use multiple-pulse techniques in the presence of magic-angle spinning to measure the degree of mixing in two different polymer blend thin films, polystyrene/poly(xylylene ether) and poly(1-methyladamantyl methacrylate) (PMAdMA)/triphenylsulfonium perfluorobutanesulfonate (TPS-PFBS), spin-coated onto mica substrates. Our earlier studies had focused on bulk systems where NMR signals are stronger, but may not be representative of thin films of the same systems that are relevant to many applications such as photoresist formulations in the electronics industry. The superiority of synthetic over natural paramagnetic mica is demonstrated by the maintenance of resolution and spinning sideband intensities (relative to bulk samples) for the synthetic mica samples. In contrast, degraded resolution and large spinning sidebands are shown to typify spectra of the natural mica samples. This approach can be applied to many other proton measurements of solid thin films, thereby greatly extending the types of systems to be investigated. Magnetic susceptibility measurements are also reported for all micas used.

  10. Tuning the microwave absorption through engineered nanostructures in co-continuous polymer blends

    NASA Astrophysics Data System (ADS)

    Prasanna Kar, Goutam; Biswas, Sourav; Bose, Suryasarathi

    2016-06-01

    Herein, we report tailor-made properties by dispersing nanostructured materials in a co-continuous polymer blend (PVDF/ABS) that is capable of shielding electromagnetic (EM) radiation. To accomplish this, lossy materials were employed like multi-walled carbon nanotubes (MWNTs), and barium titanate (BT), (which exhibit relaxation losses in the microwave frequency domain) and ferrites (like Fe3O4). To improve the state of dispersion, the MWNTs were non-covalently modified using 3,4,9,10-perylenetetracarboxylic dianhydride (PTCD) via π-π stacking, and for effective shielding the MWNTs were conjugated with either BT or Fe3O4 nanoparticles through suitable modifications. The hybrid nanoparticles were selectively localized in the PVDF phase, governed by its polarity, and exhibited excellent microwave attenuation. In order to gain insight into the dielectric and magnetic attributes, the microwave parameters were assessed systematically. Taken together, our results uncover polymer blend as a promising candidate for designing lightweight, thermally stable microwave absorber materials.

  11. Characterization of origami shape memory metamaterials (SMMM) made of bio-polymer blends

    NASA Astrophysics Data System (ADS)

    Kshad, Mohamed Ali E.; Naguib, Hani E.

    2016-04-01

    Shape memory materials (SMMs) are materials that can return to their virgin state and release mechanically induced strains by external stimuli. Shape memory polymers (SMPs) are a class of SMMs that show a high shape recoverability and which have attractive potential for structural applications. In this paper, we experimentally study the shape memory effect of origami based metamaterials. The main focus is on the Muira origami metamaterials. The fabrication technique used to produce origami structure is direct molding where all the geometrical features are molded from thermally virgin polymers without post folding of flat sheets. The study shows experimental investigations of shape memory metamaterials (SMMMs) made of SMPs that can be used in different applications such as medicine, robotics, and lightweight structures. The origami structure made from SMP blends, activated with uniform heating. The effect of blend composition on the shape memory behavior was studied. Also the influence of the thermomechanical and the viscoelastic properties of origami unit cell on the activation process have been discussed, and stress relaxation and shape recovery were investigated. Activation process of the unit cell has been demonstrated.

  12. A close look at charge generation in polymer:fullerene blends with microstructure control.

    PubMed

    Scarongella, Mariateresa; De Jonghe-Risse, Jelissa; Buchaca-Domingo, Ester; Causa', Martina; Fei, Zhuping; Heeney, Martin; Moser, Jacques-E; Stingelin, Natalie; Banerji, Natalie

    2015-03-04

    We reveal some of the key mechanisms during charge generation in polymer:fullerene blends exploiting our well-defined understanding of the microstructures obtained in pBTTT:PCBM systems via processing with fatty acid methyl ester additives. Based on ultrafast transient absorption, electro-absorption, and fluorescence up-conversion spectroscopy, we find that exciton diffusion through relatively phase-pure polymer or fullerene domains limits the rate of electron and hole transfer, while prompt charge separation occurs in regions where the polymer and fullerene are molecularly intermixed (such as the co-crystal phase where fullerenes intercalate between polymer chains in pBTTT:PCBM). We moreover confirm the importance of neat domains, which are essential to prevent geminate recombination of bound electron-hole pairs. Most interestingly, using an electro-absorption (Stark effect) signature, we directly visualize the migration of holes from intermixed to neat regions, which occurs on the subpicosecond time scale. This ultrafast transport is likely sustained by high local mobility (possibly along chains extending from the co-crystal phase to neat regions) and by an energy cascade driving the holes toward the neat domains.

  13. Internal structure-mediated ultrafast energy transfer in self-assembled polymer-blend dots.

    PubMed

    Wang, Lei; Wu, Chang-Feng; Wang, Hai-Yu; Wang, Ya-Feng; Chen, Qi-Dai; Han, Wei; Qin, Wei-Ping; McNeill, Jason; Sun, Hong-Bo

    2013-08-21

    Applications of polymeric semiconductors in organic electronics and biosensors depend critically on the nature of energy transfer in these materials. Important questions arise as to how this long-range transport degrades in amorphous condensed solids which are most amenable to low-cost optoelectronic devices and how fast energy transfer could occur. Here, we address these in disordered, densely packed nanoparticles made from green-light-harvesting host polymers (PFBT) and deep-red-emitting dopant polymers (PF-DBT5). By femtosecond selective excitation of donor (BT) units, we study in detail the internal structure-mediated energy transfer to uniformly distributed, seldom acceptor (DBT) units. It has been unambiguously demonstrated that the creation of interchain species is responsible for the limitation of bulk exciton diffusion length in polymer materials. This interchain Förster resonance energy transfer (FRET) becomes a preferred and dominant channel, and near 100% energy transfer efficiency could be achieved at high acceptor concentrations (>10 wt%). Side-chain carboxylic acid groups in functionalized polymer-blend dots slightly slow down the FRET rate, but it could not affect the Förster radius and FRET efficiency. These findings imply that a greater understanding of the role of interchain species could be an efficient approach to improve the cell efficiency.

  14. Synthesis and fuel cell characterization of blend membranes from phenyl phosphine oxide containing flourinated novel polymers

    NASA Astrophysics Data System (ADS)

    Gürtekin Seden, Merve; Baştürk, Emre; Inan, Tülay Y.; Kayaman Apohan, Nilhan; Güngör, Atilla

    2014-12-01

    Novel fluorinated poly(arylene ether)'s are synthesized from polycondensation of bis (p-hydroxy-tetrafluoro) phenyl) phenyl phosphine oxide (PFPPO-OH) with 4,4‧-dichlorodiphenyl sulfone (DCDPS) and 2,2-bis(4-hydroxyphenyl)propane (Bisfenol A) (Copolymer 1a) or 2,2-bis(4-hydroxyphenyl) hexafluoropropane (Bisphenol AF) (Copolymer 1b). The fluorinated copolymers have been blended with sulphonated poly(ether ether ketone)-SPEEK by solvent casting method. The water uptake and proton conductivity of the blend membranes decreases with the increase of copolymer content as expected, but proton conductivity values are still comparable to that of Nafion117® membrane. Addition of hydrophobic copolymer 1b to the SPEEK caused increase in water vapor transmission. Methanol permeability of the membranes is decreased to 8.2 × 10-8 cm2 s-1 and 1.3 × 10-9 cm2 s-1 by addition of Copolymer 1a and 1b, respectively and they are much lower than that of Nafion® 117 (1.21E-06 (cm2 s-1). The blend membranes endure up to 6.5 h before it starts to dissolve. Hydrogen and oxygen permeability of the blend membranes is one-hundredth of the Nafion®. Fluorinated polymer improved chemical, mechanical, and hydrolytic stability and also phenyl phosphine oxide structure in the ionomer increased the thermal stability, gas and methanol permeability and overcomed the drawbacks of the Nafion® type membranes.

  15. Structural and ionic conductivity studies of electrospun polymer blend P(VdF-co-HFP)/PMMA electrolyte membrane for lithium battery application

    SciTech Connect

    Padmaraj, O.; Satyanarayana, N.; Venkateswarlu, M.

    2015-06-24

    A novel fibrous polymer blend [(100-x) % P(VdF-co-HFP)/x % PMMA, x = 10, 20, 30, 40, 50] electrolyte membranes were prepared by electrospinning technique. Structural, thermal and surface morphology of all the compositions of electrospun polymer blend membranes were studied by using XRD, DSC & SEM. The newly developed five different compositions of polymer blend fibrous electrolyte membranes were obtained by soaking in an electrolyte solution contains 1M LiPF{sub 6} in EC: DEC (1:1,v/v). The wet-ability and conductivity of all the compositions of polymer blend electrolyte membranes are evaluated through electrolyte uptake and impedance measurements. The polymer blend [90% P(VdF-co-HFP)/10% PMMA] electrolyte membrane showed good wet-ability and high conductivity (1.788 × 10{sup −3} Scm{sup −1}) at room temperature.

  16. Adsorption of polymers, polymer blends and a diblock copolymer onto conducting polypyrrole. A study by surface analytical techniques

    NASA Astrophysics Data System (ADS)

    Chehimi, M. M.; Abel, M.-L.; Fricker, F.; Delamar, M.; Jada, A.; Brown, A. M.; Watts, J. F.

    1998-06-01

    Adsorption of PMMA and PVC, PMMA and PVC blends, and a diblock copolymer P(S/EO), onto polypyrrole (PPy) was monitored by XPS, ToF-SSIMS and inverse gas chromatography (IGC). It is shown that the solvent nature influences adsorption rate and the morphology of the coating. There is also evidence for PVC and PEO block-enrichment at the PPy-blend and PPy-P(S/EO) interfaces, respectively. L'adsorption de PMMA et PVC, de leurs mélanges (PMMA+PVC) et d'un copolymère à blocs (poly(styrène-b-oxyde d'éthylène), P(S/EO)) sur le polypyrrole (PPy) a été suivie par XPS, ToF-SSIMS et chromatographie inverse en phase gazeuse. Il est démontré que la nature du solvant influence la quantité de polymère adsorbé et la morphologie des revêtements. En outre, les interfaces PPy-(PMMA+PVC) et PPy-P(S/EO) sont riches respectivement en PVC et en blocs PEO.

  17. Synthesis and characterization of phosphonate ester and phosphonic acid containing polymers and blends

    NASA Astrophysics Data System (ADS)

    Tamber, Harinder Singh

    1997-12-01

    TGA to estimate the thermal stability of iodinated polymers. Incorporation of 13 wt% of either monomer in MMA or VBP results in radiopacity equivalent to 2 mm of aluminum a standard used in dentistry. Finally the dimethyl vinylphosphonate ester was homopolymerized and copolymerized with VBP. The aliphatic phosphonate ester was blended with cellulose acetate and cellulose acetate butyrate. The crystallinity of CA was completely impeded when 5 wt% of PDMVP was added, and the Flory interaction parameter chi obtained for PDMVP/CA was large and negative indicating a strong interaction between this pair of polymers.

  18. Microstructure and Crystal-Amorphous Interphases in Melt-Miscible Semicrystalline Polymer Blends. Ph.D. Thesis

    SciTech Connect

    Barron, C.A.

    1994-01-01

    Small-angle x ray scattering, differential scanning calorimetry, dielectric spectroscopy and dynamic mechanical thermal analysis were performed to study the microstructure of the semicrystalline polymers poly(etylene oxide) (PEO) and poly (epsilon-caprolactone) (PCL) as well as several melt miscible blends. Four amorphous polymers were blended with PEO: two which interact weakly with PEO poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) and two which are considered strongly interacting due to the formation of hydrogen bonds with PEO (two random copolymers, one containing 50% styrene and 50% hydroxystyrene (50/50 ScHS) and another of ethylene with 55% methacrylic acid (EMA55)). Further, one of the weakly interacting amorphous polymers and one of the strongly interacting polymers was selected based on its relatively high T(sub g)s. The other amorphous polymers have relatively low T(sub g)s (i.e., at or below the crystallization temperature). The solid state microstructure of miscible blends containing a semicrystalline and an amorphous polymer is shown to be critically dependent on two factors: (1) the strength of interactions between the two copolymers; and (2) the mobility of the amorphous material at the crystallization temperature. The influence of interaction strength on the region of partial order at the crystal surface (the crystal-amorphous interphase) is demonstrated. The results are consistent with theoretical predictions that this region changes from pure crystallizable material to a mixture containing both the crystalizable and the amorphous components as chi becomes more favorable. In the blends which contain a high T(sub g) amorphous polymer and in those with strong intermolecular interactions, there were no observed changes in the microstructure with crystallization temperature. Apparently, in the high T(sub g) systems, the amorphous polymer is unable to escape the interlamellar zone since it has insufficient mobility.

  19. Understanding the relationship between molecular order and charge transport properties in conjugated polymer based organic blend photovoltaic devices.

    PubMed

    Wood, Sebastian; Kim, Jong Soo; James, David T; Tsoi, Wing C; Murphy, Craig E; Kim, Ji-Seon

    2013-08-14

    We report a detailed characterization of the thin film morphology of all-polymer blend devices by applying a combined analysis of physical, chemical, optical, and charge transport properties. This is exemplified by considering a model system comprising poly(3-hexylthiophene) (P3HT) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). We show that the interactions between the two conjugated polymer components can be controlled by pre-forming the P3HT into highly ordered nanowire structures prior to blending with F8BT, and by varying the molecular weight of the F8BT. As a result, it is possible to produce films containing highly ordered P3HT with hole mobilities enhanced by three orders of magnitude over the pristine blends. Raman spectroscopy under resonant excitation conditions is used to probe the molecular order of both P3HT and F8BT phases within the blend films and these morphological studies are complemented by measurements of photocurrent generation. The resultant increase in photocurrent is associated with the enhanced charge carrier mobilities. The complementary analytical method demonstrated here is applicable to a wide range of polymer blend systems for all applications where the relationships between morphology and device performance are of interest.

  20. Polymer blend effects on fundamental properties of mesogenic phthalocyanine films fabricated by heated spin-coating method

    NASA Astrophysics Data System (ADS)

    Higashi, Takuya; Fiderana Ramananarivo, Mihary; Ohmori, Masashi; Yoshida, Hiroyuki; Fujii, Akihiko; Ozaki, Masanori

    2015-04-01

    Polymer blending effects on the properties of the mesogenic phthalocyanine thin films fabricated by heated spin-coating method were demonstrated. The spin-coated films of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) blended with poly(3-hexylthiophene) (P3HT) were prepared by controlling the temperatures of substrates and solutions with the mixed material, and the morphology and optical property of the fabricated film were studied. In the case of the low composite ratio of P3HT, the wide crack lines found in pure C6PcH2 films disappeared while maintaining the uniaxial aligned optic axis direction in the large-area with the diameters of exceeding 1 mm. The polymer blend effects were discussed by taking the anisotropic optical absorption and molecular stacking structure in the films into consideration.

  1. Breakup of a transient wetting layer in polymer blend thin films: unification with 1D phase equilibria.

    PubMed

    Coveney, Sam; Clarke, Nigel

    2013-09-20

    We show that lateral phase separation in polymer blend thin films can proceed via the formation of a transient wetting layer which breaks up to give a laterally segregated film. We show that the growth of lateral inhomogeneities at the walls in turn causes the distortion of the interface in the transient wetting layer. By addressing the 1D phase equilibria of a polymer blend thin film confined between selectively attracting walls, we show that the breakup of a transient wetting layer is due to wall-blend interactions; there are multiple values of the volume fraction at the walls which solve equilibrium boundary conditions. This mechanism of lateral phase separation should be general.

  2. Flexural properties of ethyl or methyl methacrylate-UDMA blend polymers.

    PubMed

    Kanie, Takahito; Kadokawa, Akihiko; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

    2010-10-01

    Light-curing polyethyl methacrylate (PEMA)-urethane dimethacrylate (UDMA) resins and polymethyl methacrylate (PMMA)-UDMA resins were prepared by two processes. For first step, PEMA or PMMA powders were fully dissolved in ethyl methacrylate (EMA) or methyl methacrylate (MMA) and then the PEMA-EMA/PMMA-MMA mixtures were mixed with UDMA. The flexural properties of cured PEMA-UDMA and PMMA-UDMA polymers were measured using two PEMA (Mw: 300,000-400,000 and 650,000-1,000,000) and three PMMA (Mw: 30,000-60,000, 350,000 and 650,000-1,000,000) powders with different molecular weight, four mixing ratios of PMMA-MMA, and three mixing ratios of PMMA-MMA mixture and UDMA oligomer. Polymers with PMMA(Mw: 350,000) MMA=25/50, and with PMMA(Mw: 350,000)-MMA/UDMA=1/2 and =1/1, showed no-fracture in a flexural test at 1 mm/min and flexural strength and flexural modulus showed no significant difference compared with those of commercially available heat- and self-curing acrylic resins (p>0.01). Within limitation of this investigation, methyl methacrylate-UDMA blend polymer of this composition is available for denture base resin.

  3. Molecular Interactions and Ordering in Electrically Doped Polymers: Blends of PBTTT and F4TCNQ

    SciTech Connect

    Cochran, Justin E; Junk, Matthias J. N.; Glaudell, Anne M.; Miller, P. L.; Cowart, John S.; Toney, Michael F.; Hawker, Craig J.; Chmelka, Bradley F.; Chabinyc, Michael L.

    2014-09-12

    Identifying how small molecular acceptors pack with polymer donors in thin and thick (bulk) films is critical to understanding the nature of electrical doping by charge transfer. In this study, the packing structure of the molecular acceptor tetrafluorotetracyanoquinodimethane (F4TCNQ) with the semiconducting polymer poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno-[3,2-b]thiophene) (PBTTT-C14) is examined. A combination of solid-state NMR, synchrotron X-ray scattering, and optical spectroscopy was used to determine the packing motif for blends of PBTTT-C14 and F4TCNQ in thin and bulk films. These results indicate that F4TCNQ and PBTTT-C14 order in a cofacial arrangement where charge transfer is near 100% efficient in the solid state. These results provide crucial insights into the structures and compositions of ordered domains in doped semiconducting polymers and suggest a model for the microstructure where the location of the molecular acceptors are correlated rather than randomly dispersed.

  4. Self-tracking, solvent-free low-dimensional polymer electrolyte blends with lithium salts

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Chia, F.; Ungar, G.; Wright, P. V.

    Solvent-free polymer electrolyte blends of the amphiphilic polyethoxide ( I) and the polytetrahydrofuran copolymer ( II) with LiClO 4 or LiClO 4/LiBF 4 mixture have been prepared. In II A is either CH 2 ( IIC1) or CH 2C(CH 2)CH 2 ( IID4), dc measurements using Li electrodes on the cells (Li | I/ II-Li salt | Li) demonstrate a 'self-tracking' process over ca. 24 h during which time conductivities increase from ca. 10 -6 to 10 -3 S cm -1 at 25 and 30°C. The dc results are supported by ac impedance measurements using indium tin oxide (ITO) electrodes in which the complexes undergo transitions at ca. 90°C to give a conductivity after cooling of 6×10 -4 S cm -1 at 20°C with low temperature dependence. Structural analysis and molecular dynamics modelling indicate that the cations occupy unimpeded helices of I and anions are located in the interhelical spaces. Mechanisms of 'tracking' involving shear-induced orientation of polymer I by polymer II and the redistribution of ions between I and II following imposition of the field are proposed.

  5. Improved surface properties of polyaniline films by blending with Pluronic polymers without the modification of the other characteristics.

    PubMed

    Li, Z F; Ruckenstein, E

    2003-08-15

    Films of conductive polyaniline and amphiphilic Pluronic (P105) copolymer blends were prepared by dissolving the two polymers in N-methylpyrrolidinone (NMP) followed by a slow solvent evaporation at 55 degrees C. The characteristics of both doped and undoped films were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water droplet contact angles, differential scanning calorimetry (DSC), thermal gravimetry analysis (TG), wide-angle X-ray diffraction (WAXD), and tensile strength measurements. The surface of the blends became more hydrophilic than that of the hydrophobic PANI film, but the other properties of the blends did not change appreciably for Pluronic content lower than 50 wt%. Compared to PANI films, the more hydrophilic surfaces decreased the amount of bovine serum albumin protein adsorbed. By preventing biofouling, the polyaniline-Pluronic blends can become more useful as biosensors than the polyaniline films.

  6. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    NASA Astrophysics Data System (ADS)

    Cardoso, Elisabeth C. L.; Scagliusi, Sandra R.; Lima, Luis F. C. P.; Bueno, Nelson R.; Brant, Antonio J. C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT).

  7. High density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) polymer blend studies related to recycling co-mingled plastics

    NASA Astrophysics Data System (ADS)

    Tsai, Pang-Yen

    Polymer blends of virgin high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) were studied as an attempt to relate the microstructure to the mechanical properties of the blends. The virgin blends were prepared by extrusion and then injection molded into specimens for characterization. Two of the virgin blends were tested for possible compatibilization using a styrene-ethylene-butylene-styrene (SEBS) block copolymer. In addition, six blends of post-consumer resins (PCRs) of HDPE and PET were included in this work for comparison. The moduli of the virgin blends showed positive deviation from those expected from the rule of mixtures. The synergism of the composite moduli can be explained partly by a Poisson's effect. Yield strengths of the blends molded at low injection chamber temperatures (200sp°, 230sp°, and 250sp°C) followed the rule of mixtures well, because PET filaments found in the composites had very high length to diameter ratios. When the injection chamber temperature was above the PET melting point (˜254sp°C), PET filaments were found to break down into particles, and the yield strengths of the blends coincided with the values expected from the inverse rule of mixtures. Impact strengths of the virgin blends were much less than that of a HDPE homopolymer due to poor interfacial bonding between HDPE and PET. Compatibilization appeared to be advantageous since it dramatically improved the impact strength of the virgin blends. SEM micrographs of impact fractured surfaces revealed that the improved adhesion from compatibilization and the presence of numerous uniaxially aligned PET filaments in the HDPE substrate can account for the significant increases in fracture resistance of the compatibilized blends. Mechanical performance of the PCRs was inferior to that of the virgin blends. Aside from polymer degradation and contamination due to repeated processing and handling, absence of PET filaments and interfacial bonding could be

  8. Diffusion in Immiscible Melts

    NASA Technical Reports Server (NTRS)

    Pond, R. B.

    1985-01-01

    The objective of this program is to measure the diffusion coefficients for molten Pb in Zn in the immiscible liquid-phase region. Diffusion couples of pure Pb and Zn were prepared using a shear cell. These have been placed in graphite crucibles and encapsulated in stainless steel cartridges and are awaiting the next Materials Experiment Assembly (MEA) flight opportunity. In flight, one couple will be soaked for 40 minutes at 440 deg C (just above the monotectic temperature) and the second couple will be soaked for 40 minutes 820 deg C (just above the consolute temperature). After the soak both samples will be rapidly quenched by flowing He to minimize redistribution of the immiscible phases. Post flight compositional analysis will be accomplished using X-ray fluorescence in the scanning electron microscopy.

  9. Correlation between Photovoltaic Performance and Interchain Ordering Induced Delocalization of Electronics States in Conjugated Polymer Blends.

    PubMed

    Chandrasekaran, Naresh; Gann, Eliot; Jain, Nakul; Kumar, Anshu; Gopinathan, Sreelekha; Sadhanala, Aditya; Friend, Richard H; Kumar, Anil; McNeill, Christopher R; Kabra, Dinesh

    2016-08-10

    In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100% regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10% increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92% regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.

  10. Dynamic-Mechanical and Impact Properties of Conductive Polymer Blends Based on Polypropylene

    NASA Astrophysics Data System (ADS)

    Acierno, Domenico; Russo, Pietro

    2007-04-01

    Plastic materials with significant electrical properties are getting more and more interest as witnessed by the wide spectra of industrial applications such as high performance textiles, fabrics for military, electronics and display technologies, automotive field (fuel delivery lines, exterior body panels) and so on. In this context, in the last decade an increasing interest has been devoted to the use of intrinsically conductive polymers such as polyaniline (PANI). In this work melt blended formulations based on polypropylene, containing 5% and 10% by weight of PANI, were investigated in terms of dynamic-mechanical and impact properties. Preliminary results indicate that, besides the processing conditions, inclusions of PANI make a general worsening of the dumping behaviour, especially in the rubbery region. Anyway, it is evident a clear improvement of the impact resistance with respect to the matrix, processed under the same conditions and taken as a reference, for the 5wt % system.

  11. The effect of nanosize ZnO on the properties of the selected polymer blend composites

    NASA Astrophysics Data System (ADS)

    Grigalovica, A.; Bochkov, I.; Merijs Meri, R.; Zicans, J.; Grabis, J.; Kotsilkova, R.; Borovanska, I.

    2012-08-01

    In the current research the effect of ZnO nanoparticles on the structure and properties of common thermoplastic polymers (polyoxymethylene (POM), polypropylene (PP), ethylene-α-octene copolymers (EOC)) and their binary blends is investigated. EOC content in the composites varies from 0 to 50 wt. %. The amount of nanostructured ZnO filler in the composites is changed in the interval from 0 to 5 wt. %. Tensile and frictional properties of ZnO modified nanocomposites are investigated. Results of the investigation show that ZnO additions cause increment in stiffness and strength as well as coefficient of friction of the investigated nanocomposites. The effect of ZnO modifier is the highest at low EOC content. The effect of ZnO is strongly dependent on the compatibility and crystallinity of the investigated nanocomposites.

  12. Direct detection of photoinduced charge transfer complexes in polymer fullerene blends

    NASA Astrophysics Data System (ADS)

    Behrends, Jan; Sperlich, Andreas; Schnegg, Alexander; Biskup, Till; Teutloff, Christian; Lips, Klaus; Dyakonov, Vladimir; Bittl, Robert

    2012-03-01

    We report transient electron paramagnetic resonance (trEPR) measurements with submicrosecond time resolution performed on a polymer:fullerene blend consisting of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) at low temperatures. The trEPR spectrum immediately following photoexcitation reveals signatures of spin-correlated polaron pairs. The pair partners (positive polarons in P3HT and negative polarons in PCBM) can be identified by their characteristic g values. The fact that the polaron pair states exhibit strong non-Boltzmann population unambiguously shows that the constituents of each pair are geminate, i.e., originate from one exciton. We demonstrate that coupled polaron pairs are present even several microseconds after charge transfer and suggest that they embody the intermediate charge transfer complexes that form at the donor/acceptor interface and mediate the conversion from excitons into free charge carriers.

  13. In vitro and in vivo performance of dexamethasone loaded PLGA microspheres prepared using polymer blends.

    PubMed

    Gu, Bing; Wang, Yan; Burgess, Diane J

    2015-12-30

    The foreign body reaction is the major cause of the dysfunction and relatively short lifetime associated with implanted glucose biosensors. An effective strategy to maintain sensor functionality is to apply biocompatible coatings that elute drug to counter the negative tissue reactions. This has been achieved using dexamethasone releasing poly(lactic-co-glycolic acid) (PLGA) microspheres embedded in a polyvinyl alcohol (PVA) hydrogel coating. Accordingly, the biosensor lifetime relies on the duration and dose of drug release from the coating. To achieve long-term drug release mixed populations of microspheres have been used. In the current study, microspheres were prepared by blending low (25KDa) and high (113KDa) molecular weight PLGA at different mass ratios to overcome problems associated with mixing multiple populations of microspheres. "Real-time" in vitro studies demonstrated dexamethasone release for approximately 5 months. An accelerated method with discriminatory ability was developed to shorten drug release to less than 2 weeks. An in vivo pharmacodynamics study demonstrated efficacy against the foreign body reaction for 4.5 months. Such composite coatings composed of PLGA microspheres prepared using polymer blends could potentially be used to ensure long-term performance of glucose sensors.

  14. Degradation behavior of polymer blend of isotactic polypropylenes with and without unsaturated chain end group

    PubMed Central

    Nakatani, Hisayuki; Kurniawan, Dodik; Taniike, Toshiaki; Terano, Minoru

    2008-01-01

    In this work, the relationship between the unsaturated chain end group content and the thermal oxidative degradation rate was systematically studied with binary polymer blends of isotactic polypropylene (iPP) with and without the unsaturated chain end group. The iPPs with and without the unsaturated chain end group were synthesized by a metallocene catalyst in the absence of hydrogen and by a Ziegler catalyst in the presence of one, respectively. The thermal oxidative degradation rate of the binary iPP blends was estimated from the molecular weight and the apparent activation energy (ΔE), which were obtained through size exclusion chromatography (SEC) and thermogravimetric analysis (TGA) measurements, respectively. These values exhibited a negative correlation against the mole content of the unsaturated chain end group. The thermal oxidative degradation rate apparently depends on the content of the unsaturated chain end group. This tendency suggests that the unsaturated chain end acts as a radical initiator of the iPP degradation reaction. PMID:27877968

  15. Ion Transport and Discharge Characteristics of Polymer Blend (PVP/PVA) Electrolyte Films Doped with Potassium Iodide

    NASA Astrophysics Data System (ADS)

    Umadevi, C.; Mohan, K. R.; Achari, V. B. S.; Sharma, A. K.; Rao, V. V. R. N.

    2010-12-01

    Solid polymer blend electrolyte films based on PVP/PVA complexed with KI were prepared by the solution cast technique. Various experimental techniques such as electrical conductivity and transport number measurement were used to characterize the polymer electrolyte films. Electrochemical cells with the polymer electrolytes (PVP+PVA+KI) were fabricated in the configuration K/(PVP+PVA+KI)/ (I2+C+electrode). The discharge characteristics of the cells were studied under a constant load of 100 KΩ. The open-circuit voltage, short-circuit current and discharge time for the plateau region are measured. Several other cell parameters were evaluated and are reported.

  16. Internal structure-mediated ultrafast energy transfer in self-assembled polymer-blend dots

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Wu, Chang-Feng; Wang, Hai-Yu; Wang, Ya-Feng; Chen, Qi-Dai; Han, Wei; Qin, Wei-Ping; McNeill, Jason; Sun, Hong-Bo

    2013-07-01

    Applications of polymeric semiconductors in organic electronics and biosensors depend critically on the nature of energy transfer in these materials. Important questions arise as to how this long-range transport degrades in amorphous condensed solids which are most amenable to low-cost optoelectronic devices and how fast energy transfer could occur. Here, we address these in disordered, densely packed nanoparticles made from green-light-harvesting host polymers (PFBT) and deep-red-emitting dopant polymers (PF-DBT5). By femtosecond selective excitation of donor (BT) units, we study in detail the internal structure-mediated energy transfer to uniformly distributed, seldom acceptor (DBT) units. It has been unambiguously demonstrated that the creation of interchain species is responsible for the limitation of bulk exciton diffusion length in polymer materials. This interchain Förster resonance energy transfer (FRET) becomes a preferred and dominant channel, and near 100% energy transfer efficiency could be achieved at high acceptor concentrations (>10 wt%). Side-chain carboxylic acid groups in functionalized polymer-blend dots slightly slow down the FRET rate, but it could not affect the Förster radius and FRET efficiency. These findings imply that a greater understanding of the role of interchain species could be an efficient approach to improve the cell efficiency.Applications of polymeric semiconductors in organic electronics and biosensors depend critically on the nature of energy transfer in these materials. Important questions arise as to how this long-range transport degrades in amorphous condensed solids which are most amenable to low-cost optoelectronic devices and how fast energy transfer could occur. Here, we address these in disordered, densely packed nanoparticles made from green-light-harvesting host polymers (PFBT) and deep-red-emitting dopant polymers (PF-DBT5). By femtosecond selective excitation of donor (BT) units, we study in detail the internal

  17. Blends of enteric and GIT-insoluble polymers used for film coating: physicochemical characterization and drug release patterns.

    PubMed

    Lecomte, F; Siepmann, J; Walther, M; MacRae, R J; Bodmeier, R

    2003-05-20

    THE OBJECTIVES OF THIS STUDY WERE: (i). to use blends of gastrointestinal tract (GIT)-insoluble and enteric polymers (ethyl cellulose and Eudragit L) as coating materials for multiparticulate controlled release dosage forms; (ii). to investigate the effects of the polymer blend ratio and coating level on the resulting drug release patterns; and (iii). to explain the observed phenomena based on the physicochemical properties of the systems. Propranolol HCl-loaded pellets were coated in a fluidized bed coater with organic polymer solutions; thin, drug-containing and drug-free, polymeric films were prepared using a casting knife. In vitro drug release, water uptake and dry weight loss studies were performed in 0.1 M HCl and phosphate buffer pH 7.4, respectively. The apparent drug diffusion coefficients within the polymeric systems were determined using different experimental and theoretical techniques (side-by-side diffusion cells, in vitro drug release from thin films; exact and approximate solutions of Fick's second law of diffusion). A broad range of drug release patterns from coated pellets could be achieved by varying the GIT-insoluble:enteric polymer blend ratio. With increasing relative amounts of Eudragit L, the release rates in both media significantly increased. The increase at low pH could be attributed to an increase in water uptake, as observed with thin films. Interestingly, only partial Eudragit L leaching occurred in phosphate buffer pH 7.4 even at high enteric polymer contents, indicating that the GIT-insoluble polymer effectively hindered the dissolution of the entrapped Eudragit L. At high pH, both polymer leaching and polymer swelling contributed to the control of drug release. The determined apparent drug diffusion coefficients take the two effects adequately into account.

  18. Conductivity studies of LiCF3SO3 doped PVA: PVdF blend polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Tamilselvi, P.; Hema, M.

    2014-03-01

    Different composition of lithium ion conducting PVA: PVdF: Lithium triflate (LiCF3SO3) polymer electrolytes have been prepared by solution casting technique. Dielectric and conductivity studies have been carried out for the prepared samples. The addition of salt into the polymer matrix increases the ionic conductivity of blend polymer electrolytes. The conductivity analysis reveals 80PVA: 20PVdF: 15LiCF3SO3 polymer electrolyte exhibits the maximum ionic conductivity of 2.7×10-3 S cm-1 at 303 K. The temperature dependence of ionic conductivity for all the composition of PVA: PVdF: LiCF3SO3 polymer films obey Arrhenius relation. Low activation energy has been obtained for highest conducting sample. The dielectric spectra show absolute β-relaxation peak.

  19. Tailoring Nanoscale Morphology of Polymer:Fullerene Blends Using Electrostatic Field.

    PubMed

    Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; Lindemann, William; Wang, Wenjie; Grieser, Eric; Venkatesan, Swaminathan; Ngo, Evan; Bhattacharjee, Ujjal; Strzalka, Joseph; Jiang, Zhang; Qiao, Qiquan; Petrich, Jacob; Vaknin, David; Chaudhary, Sumit

    2017-01-25

    To tailor the nanomorphology in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to control; wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions-horizontal (H), tilted (T), and vertical (V)-relative to the plane of the substrate. Surface and bulk characterizations of the field-treated BHJs affirmed that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. Using E-field treatment, we achieved favorable morphologies with efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10(-4) ± 1.6 × 10(-4) cm(2) V(-1) s(-1) and (2) the power conversion efficiency (PCE) of conventional and inverted OPVs up to 2.58 ± 0.02% and 4.1 ± 0.40%, respectively. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.

  20. Triple shape memory effects of cross-linked polyethylene/polypropylene blends with cocontinuous architecture.

    PubMed

    Zhao, Jun; Chen, Min; Wang, Xiaoyan; Zhao, Xiaodong; Wang, Zhenwen; Dang, Zhi-Min; Ma, Lan; Hu, Guo-Hua; Chen, Fenghua

    2013-06-26

    In this paper, the triple shape memory effects (SMEs) observed in chemically cross-linked polyethylene (PE)/polypropylene (PP) blends with cocontinuous architecture are systematically investigated. The cocontinuous window of typical immiscible PE/PP blends is the volume fraction of PE (v(PE)) of ca. 30-70 vol %. This architecture can be stabilized by chemical cross-linking. Different initiators, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DHBP), dicumylperoxide (DCP) coupled with divinylbenzene (DVB) (DCP-DVB), and their mixture (DHBP/DCP-DVB), are used for the cross-linking. According to the differential scanning calorimetry (DSC) measurements and gel fraction calculations, DHBP produces the best cross-linking and DCP-DVB the worst, and the mixture, DHBP/DCP-DVB, is in between. The chemical cross-linking causes lower melting temperature (Tm) and smaller melting enthalpy (ΔHm). The prepared triple shape memory polymers (SMPs) by cocontinuous immiscible PE/PP blends with v(PE) of 50 vol % show pronounced triple SMEs in the dynamic mechanical thermal analysis (DMTA) and visual observation. This new strategy of chemically cross-linked immiscible blends with cocontinuous architecture can be used to design and prepare new SMPs with triple SMEs.

  1. Illustration of Electrical and Optical Properties of Some Conducting Polymers Blends

    NASA Astrophysics Data System (ADS)

    Bhadra, Jolly

    Conductive polymers (CP) are gaining interest day by day due to their growing fields of sophisticated uses. Conventional polymers are generally known to be insulators with their limited use as electrical insulators in any device making purpose. But these have high degree of mechanical strength and mold procesability to facilitate them constructing desirable materials. CPs on the other hand can attain near metallic electrical conductivity at their highest doped state. So they can be thought as good replacement for metals in many aspects. But the problem is not so simple, as the CPs at highest doped state are not at all processable, have very low mechanical strength and mostly not stable also. CPs have characteristic feature of tunable electrical and optical properties, which make them suitable for various device applications. In fact, retaining the electrical and optical properties, If some strength and processability property can be incorporated, CPs can play havoc. That is no wonder why CPs demand in US is rising by 5.8 percent annually. Polyaniline (PANI) and polypyrrole (PPY) are particularly attractive materials amongst CPs due to their excellent environmental stability along with other features such as, low cost, high conductivity upon doping, and ease of synthesis. In spite of all these advantages, their device applications are limited due to their unprocessable nature. These can neither be solution processable (as they are not soluble in any solvent) nor melt processable (as they decompose before reaching a softening or melting temperature). There are various methods to overcome these problems, one of them, which has been adopted by us is to blend the CPs with some conventional polymers, like polyvinyl alcohol (PVA), polyvinyl Chloride (PVC), poly-methyl-methacrylate (PMMA) etc. The resulting blend will obviously have improved mechanical property of the latter and electrical conductivity of the former. However it is seen that in this process one has to

  2. Influence of selenophene on the properties of semi-random polymers and their blends with PC61BM

    NASA Astrophysics Data System (ADS)

    Rudenko, Andrey E.; Noh, Sangtaik; Thompson, Barry C.

    2013-12-01

    In an effort to broaden the absorption of conjugated polymers, atomistic bandgap control was applied to the semi-random polymer architecture. Here, we report the physical properties of semi-random polyselenophenes as compared to analogous polythiophenes. In order to examine the effect of the selenium heteroatom on the optical properties of the polymers, UV-vis spectra were studied and it was found that all polyselenophenes exhibit lower bandgaps and higher absorption coefficients in thin films. Further, differential scanning calorimetry and grazing incidence x-ray diffraction results indicate that semi-random polyselenophenes are semicrystalline polymers and their (100) interchain distances are shorter than in the case of semi-random polythiophenes, which may be responsible for higher absorption coefficients. To probe the effect of the selenium heteroatom on the nano-organization of these polymers and their blends with PC61BM, thin films were studied by transmission electron microscopy (TEM). The TEM images show a segregation between more densely packed areas from less densely packed areas in the pristine polymer films, which is more pronounced for polyselenophenes than for polythiophenes. The blends of polyselenophenes with PC61BM do not show the well-defined segregation observed for the polythiophene analogues. However, the broadened and extended absorption of semi-random polyselenophenes translates into an extended photocurrent response in the photovoltaic devices, as evidenced by external quantum efficiency measurements.

  3. Transient absorption spectroscopy studies on polythiophene-fullerene bulk heterojunction organic blend films sensitized with a low-bandgap polymer.

    PubMed

    Löslein, Heiko; Ameri, Tayebeh; Matt, Gebhard J; Koppe, Markus; Egelhaaf, Hans J; Troeger, Anna; Sgobba, Vito; Guldi, Dirk M; Brabec, Christoph J

    2013-07-12

    Recently, the concept of near-infrared sensitization is successfully employed to increase the light harvesting in large-bandgap polymer-based solar cells. To gain deeper insights into the operation mechanism of ternary organic solar cells, a comprehensive understanding of charge transfer-charge transport in ternary blends is a necessity. Herein, P3HT:PCPDTBT:PCBM ternary blend films are investigated by transient absorption spectroscopy. Hole transfer from PCPDTBT-positive polarons to P3HT in the P3HT:PCPDTBT:PCBM 0.9:0.1:1 blend film can be visualized. This process evolves within 140 ps and is discussed with respect to the proposed charge-generation mechanisms.

  4. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm2/Vs.

    PubMed

    Smith, Jeremy; Zhang, Weimin; Sougrat, Rachid; Zhao, Kui; Li, Ruipeng; Cha, Dongkyu; Amassian, Aram; Heeney, Martin; McCulloch, Iain; Anthopoulos, Thomas D

    2012-05-08

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

  5. Periodic porous stripe patterning in a polymer blend film induced by phase separation during spin-casting.

    PubMed

    Kim, Jae-Kyung; Taki, Kentaro; Nagamine, Shinsuke; Ohshima, Masahiro

    2008-08-19

    A periodic striping pattern with microscale pore size is observed on the surface of thin films prepared by spin-casting from a polystyrene (PS) and polyethylene glycol (PEG) blend solution. The pattern is created by the convection generated by thermal gradients in the solution between the substrate and film solution during solvent evaporation, the radial flow of the spin-coated solution, and the primary and secondary phase separation of the PS and PEG solutions. The formation mechanism of the periodic porous stripe pattern is discussed, wherein the effects of the polymer blend weight ratio, polymer concentration, and drying rate on the formation of the periodic porous striping pattern are investigated using scanning electron and atomic force microscopy.

  6. Study on micro structural and electrical properties of FeCl3 doped HPMC/PVP polymer blend films

    NASA Astrophysics Data System (ADS)

    Somashekarappa, H.; Prakash, Y.; Urs, R. Gopal Krishne; Somashekar, R.

    2015-06-01

    Solid polymer electrolyte (SPE) based on Hydroxypropylemethylcellulose (HPMC) and Polyvinylpyrrolidone (PVP) polymer blend films complexed with different weight ratio of FeCl3 were prepared using solution casting method and investigated using X-ray line profile analysis. Here an attempt has been made to study the changes in crystal imperfection parameters in HPMC/PVP blend films with the increase in concentration of FeCl3. The obtained results shows that decrease in micro crystalline parameters results in increase in the amorphous nature of the film yields more flexibility, biodegradability and good ionic conductivity. AC conductivity measurements in these films show that the conductivity increases as the concentration of FeCl3 increases. These films were suitable for electro chemical applications.

  7. Characterization of poly(butylene succinate)/glycerol co-plasticized thermoplastic gelatin prepared by melt blending

    NASA Astrophysics Data System (ADS)

    Oliviero, Maria; Sorrentino, Andrea; Iannace, Salvatore

    2015-12-01

    Biodegradable thermoplastic poly(butylene succinate)/gelatin (PBS/TPG) blends with various blending ratios were prepared by melt mixing technique. The main goal of these blends is to improve the water sensitivity of thermoplastic gelatin by blending it with a hydrophobic biodegradable polymer obtained also from renewable resources. The incorporation of PBS yielded a decrease in absorbed moisture. Under the relative humidity 50 and 100%, the absorbed moisture obtained values were 19 and 229% for pure TPG, 12.3 and 127% for TPG/PBS(80/20), and 1.7 and 37% for TPG/PBS(20/80), respectively. The water resistance increased only for the samples containing a high value of PBS (>40%wt). Furthermore, mechanical properties and morphological analyses revealed that PBS/TPG blends were immiscible.

  8. Structural and transport properties of PVC blend PEG doped with Mg(ClO4)2 solid polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Ramesh, C. H.; Reddy, M. Jaipal; Kumar, J. Siva; Reddy, K. Narasimha

    2014-04-01

    An attempt was made to investigate the effect of Mg(ClO4)2 concentration in PVC-PEG blend polymer electrolyte system. Solid polymer electrolyte films of PVC-PEG-Mg(ClO4)2 have been prepared by using solution - casting process. Structural and transport properties have been studied by employing experimental tools like XRD, FT-IR and DC electrical conductivity. The XRD, FTIR studies were confirmed the formation of a polymer-salt complex. The conductivity results indicated that the incorporation of Mg(ClO4)2 salt into PVC-PEG polymer; at low concentrations the increase in the conductivity is large, but at higher concentrations the increase in conductivity is modest. Using this electrolyte, an electrochemical cells have been fabricated with the configuration Mg/ (PVC-PEG-Mg(ClO4)2) electrolyte / (I2 + C + electrolyte) and its discharge characteristics were determined.

  9. Combining polyethylene and polypropylene: Enhanced performance with PE/iPP multiblock polymers.

    PubMed

    Eagan, James M; Xu, Jun; Di Girolamo, Rocco; Thurber, Christopher M; Macosko, Christopher W; LaPointe, Anne M; Bates, Frank S; Coates, Geoffrey W

    2017-02-24

    Polyethylene (PE) and isotactic polypropylene (iPP) constitute nearly two-thirds of the world's plastic. Despite their similar hydrocarbon makeup, the polymers are immiscible with one another. Thus, common grades of PE and iPP do not adhere or blend, creating challenges for recycling these materials. We synthesized PE/iPP multiblock copolymers using an isoselective alkene polymerization initiator. These polymers can weld common grades of commercial PE and iPP together, depending on the molecular weights and architecture of the block copolymers. Interfacial compatibilization of phase-separated PE and iPP with tetrablock copolymers enables morphological control, transforming brittle materials into mechanically tough blends.

  10. Nanodomain formation in a liquid polymer blend: The initial stages of phase separation

    SciTech Connect

    Marcus, A.H.; Hussey, D.M.; Diachun, N.A.; Fayer, M.D.

    1995-11-08

    The morphology of nanodomain structures in binary polymer blends of a random copolymer and a homopolymer is determined using electronic excitation transport (EET) studies. The experimental system employed is a copolymer, 6.5% atactic poly(methyl methacrylate-{ital co}-2-vinyl naphthalene) [P(MMA-2VN)], in atactic poly(vinyl acetate) (PVAc). The naphthalene groups serve as chromophores in the EET experiments. The mixtures are prepared such that initially the P(MMA-2VN) chains are randomly distributed in the PVAc matrix. The nanodomains are formed while low-concentration mixtures of the P(MMA-2VN) in PVAc are held at constant temperature in the melt state ({ital T}{gt}{ital T}{sub {ital g}}), above the temperature at which phase separation occurs. In the melt the chains diffuse, and P(MMA-2VN) chains aggregate until the temperature is quenched below {ital T}{sub {ital g}}. The structures of the resulting domains are examined with time-resolved fluorescence depolarization measurements, and the data are analyzed using an analytical theory to model EET among interacting polymer chains. The agreement between theory and data is very good. The results of the analysis indicate that the nanodomains correspond to aggregates with a characteristic size equal to the radius of gyration of the copolymer, {ital R}{sub {ital g}}. The number of P(MMA-2VN) chains in aggregates prepared under different conditions is determined. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  11. The use of rheology to elucidate the granulation mechanisms of a miscible and immiscible system during continuous twin-screw melt granulation.

    PubMed

    Monteyne, Tinne; Heeze, Liza; Mortier, Séverine Thérèse F C; Oldörp, Klaus; Nopens, Ingmar; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-08-20

    Twin-screw hot melt granulation (TS HMG) is a valuable, but still unexplored alternative to granulate temperature and moisture sensitive drugs in a continuous way. Recently, the material behavior of an immiscible drug-binder blend during TS HMG was unraveled by using a rheometer and differential scanning calorimetry (DSC). Additionally, vibrational spectroscopic techniques proved the link between TS HMG and rheology since equal interactions at molecular level did occur in both processes. This allowed to use a rheometer to gain knowledge of the material behavior during hot melt processing of an immiscible drug-binder blend. However, miscibility of a drug-binder formulation and drug-binder interactions appear to influence the rheological properties and, hence conceivably also the granulation mechanism. The aim of this research was to examine if the TS HMG process of a miscible formulation system is comparable with the mechanism of an immiscible system and to evaluate whether rheology still serves as a useful tool to understand and optimize the hot melt granulation (HMG) process. The executed research (thermal analysis, rheological parameters and spectroscopic data) demonstrated the occurrence of a high and broad tan(δ) curve without a loss peak during the rheological temperature ramp which implies a higher material deformability without movement of the softened single polymer chains. Spectroscopic analysis revealed drug-polymer interactions which constrain the polymer to flow independently. As a result, the binder distribution step, which generally follows the immersion step, was hindered. This insight assisted the understanding of the granule properties. Inhomogeneous granules were produced due to large initial nuclei or adhesion of multiple smaller nuclei. Consequently, a higher granulation temperature was required in order to get the binder more homogeneously distributed within the granules.

  12. Assessing the Strength Enhancement of Heterogeneous Networks of Miscible Polymer Blends

    NASA Astrophysics Data System (ADS)

    Giller, Carl; Roland, Mike

    2013-03-01

    At the typical crosslink densities of elastomers, the failure properties vary inversely with mechanical stiffness, so that compounding entails a compromise between stiffness and strength. Our approach to circumvent this conventional limitation is by forming networks of two polymers that: (i) are thermodynamically miscible, whereby the chemical composition is uniform on the segmental level; and (ii) have markedly different reactivities for network formation. The resulting elastomer consists of one highly crosslinked component and one that is lightly or uncrosslinked. This disparity in crosslinking causes their respective contributions to the network mechanical response to differ diametrically. Earlier results showed some success with this approach for thermally crosslinked blends of 1,2-polybutadiene (PVE) and polyisoprene (PI), as well as ethylene-propylene copolymer (EPM) and ethylene-propylene-diene random terpolymer (EPDM), taking advantage of their differing reactivities to sulfur. In this work we demonstrate the miscibility of polyisobutylene (PIB) with butyl rubber (BR) (a copolymer of PIB and polyisoprene) and show that networks in which only the BR is crosslinked possess greater tensile strengths than neat BR over the same range of moduli. Office of Naval Research

  13. Ternary blend polymer solar cells with self-assembled structure for enhancing power conversion efficiency

    NASA Astrophysics Data System (ADS)

    Yang, Zhenhua; Li, Hongfei; Nam, Chang-Yong; Kisslinger, Kim; Satija, Sushil; Rafailovich, Miriam

    Bulk heterojunction (BHJ) polymer solar cells are an area of intense interest due to their advantages such as mechanical flexibility. The active layer is typically spin coated from the solution of polythiophene derivatives (donor) and fullerenes (acceptor) and interconnected domains are formed because of phase separation. However, the power conversion efficiency (PCE) of BHJ solar cell is restricted by the disordered inner structures in the active layer, donor or acceptor domains isolated from electrodes. Here we report a self-assembled columnar structure formed by phase separation between (PCDTBT) and polystyrene (PS) for the active layer morphology optimization. The BHJ solar cell device based on this structure is promising for exhibiting higher performance due to the shorter carrier transportation pathway and larger interfacial area between donor and acceptor. The surface morphology is investigated with atomic force microscopy (AFM) and the columnar structure is studied by investigation of cross-section of the blend thin film of PCDTBT and PS under the transmission electron microscopy (TEM). The different morphological structures formed via phase segregation are correlated with the performance of the BHJ solar cells.

  14. Characterization of CH3SO3H-doped PMMA/PVP blend-based proton-conducting polymer electrolytes and its application in primary battery

    NASA Astrophysics Data System (ADS)

    Ambika, C.; Hirankumar, G.

    2016-02-01

    Various compositions of solid blend polymer electrolytes based on poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) complexed with methanesulfonic acid (MSA) as proton donor were prepared by solution casting technique. The complex nature of polymer blend with MSA was confirmed by Fourier transform infrared spectroscopy. Good thermal stability of PMMA/PVP blend polymer electrolyte was identified by thermogravimetric analysis. The surface morphology of the prepared electrolytes was studied through optical microscopy. Ion transport number was determined in the range of 0.93-0.97 for proton-conducting blend polymer electrolytes. The maximum conductivity value was calculated as 2.51 × 10-5 S/cm at 303 K for 14.04 mol% MSA-doped polymer electrolytes. Dielectric studies were also carried out. The electrochemical stability window of blend polymer electrolyte was found to be 1.82 V. Primary proton battery was fabricated with Zn + ZnSO4·7H2O/solid polymer electrolytes/MnO2. The discharge characteristics were studied at constant current drain of 5, 20 and 50 μA. The energy and power density were calculated as 0.27 W h kg-1 and 269.23 mW kg-1 for 20 μA of discharge, respectively.

  15. Studies on immiscible alloys

    NASA Technical Reports Server (NTRS)

    Otto, G.

    1976-01-01

    To illustrate the behavior of immiscible liquids of different densities in zero-gravity and to determine the rate of coalescence like droplets, a demonstration experiment was performed on the Skylab 4 mission. Dispersions of oil-in-water and of water-in-oil were prepared by the astronauts and their appearance photographed over a time span of 10 hours. The experiment indicated that all emulsions were stable over this period and that the coalescent rate was at least 3 times 10 to the 5th power times smaller on Skylab than on earth. The recorded melting of a cylindrical piece of ice on Skylab 3 is used to study the mode of heat transfer for the latent heat of melting in low-gravity.

  16. Confined Pattern-Directed Assembly of Polymer-Grafted Nanoparticles in a Phase Separating Blend with a Homopolymer Matrix.

    PubMed

    Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Douglas, Jack F; Stafford, Christopher M; Kumar, Sanat K; Raghavan, Dharmaraj; Karim, Alamgir

    The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. Classic binary polymer blend phase separation related morphology transitions, from discrete AuPS domains to bicontinuous to inverse domain structure with increasing nanoparticle composition is observed, yet the kinetics of the AuPS/PMMA polymer blends system exhibit unique features compared to the parent PS/PMMA homopolymer blend. We further illustrate how to pattern-align the phase-separated AuPS nanoparticle domain shape, size and location through the imposition of a simple and novel external symmetry-breaking perturbation via soft-lithography. Specifically, submicron-sized topographically patterned elastomer confinement is introduced to direct the nanoparticles into kinetically controlled long-range ordered domains, having a dense yet well-dispersed distribution of non-crystallizing nanoparticles. The simplicity, versatility and roll-to-roll adaptability of this novel method for controlled nanoparticle assembly should make it useful in creating desirable patterned nanoparticle domains for a variety of functional materials and applications.

  17. n-Type semiconducting naphthalene diimide-perylene diimide copolymers: controlling crystallinity, blend morphology, and compatibility toward high-performance all-polymer solar cells.

    PubMed

    Hwang, Ye-Jin; Earmme, Taeshik; Courtright, Brett A E; Eberle, Frank N; Jenekhe, Samson A

    2015-04-08

    Knowledge of the critical factors that determine compatibility, blend morphology, and performance of bulk heterojunction (BHJ) solar cells composed of an electron-accepting polymer and an electron-donating polymer remains limited. To test the idea that bulk crystallinity is such a critical factor, we have designed a series of new semiconducting naphthalene diimide (NDI)-selenophene/perylene diimide (PDI)-selenophene random copolymers, xPDI (10PDI, 30PDI, 50PDI), whose crystallinity varies with composition, and investigated them as electron acceptors in BHJ solar cells. Pairing of the reference crystalline (crystalline domain size Lc = 10.22 nm) NDI-selenophene copolymer (PNDIS-HD) with crystalline (Lc = 9.15 nm) benzodithiophene-thieno[3,4-b]thiophene copolymer (PBDTTT-CT) donor yields incompatible blends, whose BHJ solar cells have a power conversion efficiency (PCE) of 1.4%. However, pairing of the new 30PDI with optimal crystallinity (Lc = 5.11 nm) as acceptor with the same PBDTTT-CT donor yields compatible blends and all-polymer solar cells with enhanced performance (PCE = 6.3%, Jsc = 18.6 mA/cm(2), external quantum efficiency = 91%). These photovoltaic parameters observed in 30PDI:PBDTTT-CT devices are the best so far for all-polymer solar cells, while the short-circuit current (Jsc) and external quantum efficiency are even higher than reported values for [70]-fullerene:PBDTTT-CT solar cells. The morphology and bulk carrier mobilities of the polymer/polymer blends varied substantially with crystallinity of the acceptor polymer component and thus with the NDI/PDI copolymer composition. These results demonstrate that the crystallinity of a polymer component and thus compatibility, blend morphology, and efficiency of polymer/polymer blend solar cells can be controlled by molecular design.

  18. Poly vinyl acetate and ammonio methacrylate copolymer as unconventional polymer blends increase the mechanical robustness of HPMC matrix tablets.

    PubMed

    Ali, R; Dashevsky, A; Bodmeier, R

    2017-01-10

    The objective was to investigate poly vinyl acetate (Kollicoat(®) SR 30 D) and ammonio methacrylate copolymer (Eudragit(®) RL 30 D) blends as coatings to increase the mechanical robustness of hydroxypropyl methylcellulose (HPMC) matrix tablets. Poly vinyl acetate (Kollicoat(®) SR 30 D - KSR) was selected for its flexibility and ammonio methacrylate copolymer (Eudragit(®) RL 30 D - ERL) because of its high permeability. Films based on KSR:ERL blends were prepared by casting or spraying aqueous dispersions of these polymers and were characterized by water uptake, dry mass loss and mechanical properties. KSR:ERL blends were investigated as coating materials to improve the robustness, mechanical strength and drug release from the HPMC matrix tablets containing propranolol HCl, caffeine and carbamazepine as model drugs. Both HPMC and the polymer coating affected the propranolol release. The release and the mechanical properties could be easily adjusted by varying the polymer blend ratio. The flexibility increased with increasing KSR content. At an 8% w/w coating level, a force of 3.2N was required to rupture the coating of the swollen tablet after 16h in the release medium; the coated tablets were thus robust to withstand gastrointestinal forces. The coating level (6%-10%, w/w) and dissolution agitation rate (50rpm to 150rpm) had no effect on the drug release. The water-insoluble carbamazepine was not released from the coated tablets as HPMC erosion, which is necessary for the release of a poorly water-soluble drug was hindered by the coating. The release of the water-soluble propranolol increased with increasing drug content and decreased with increasing HPMC content.

  19. Moving through the phase diagram: morphology formation in solution cast polymer-fullerene blend films for organic solar cells.

    PubMed

    Schmidt-Hansberg, Benjamin; Sanyal, Monamie; Klein, Michael F G; Pfaff, Marina; Schnabel, Natalie; Jaiser, Stefan; Vorobiev, Alexei; Müller, Erich; Colsmann, Alexander; Scharfer, Philip; Gerthsen, Dagmar; Lemmer, Uli; Barrena, Esther; Schabel, Wilhelm

    2011-11-22

    The efficiency of organic bulk heterojunction solar cells strongly depends on the multiscale morphology of the interpenetrating polymer-fullerene network. Understanding the molecular assembly and the identification of influencing parameters is essential for a systematic optimization of such devices. Here, we investigate the molecular ordering during the drying of doctor-bladed polymer-fullerene blends on PEDOT:PSS-coated substrates simultaneously using in situ grazing incidence X-ray diffraction (GIXD) and laser reflectometry. In the process of blend crystallization, we observe the nucleation of well-aligned P3HT crystallites in edge-on orientation at the interface at the instant when P3HT solubility is crossed. A comparison of the real-time GIXD study at ternary blends with the binary phase diagrams of the drying blend film gives evidence of strong polymer-fullerene interactions that impede the crystal growth of PCBM, resulting in the aggregation of PCBM in the final drying stage. A systematic dependence of the film roughness on the drying time after crossing P3HT solubility has been shown. The highest efficiencies have been observed for slow drying at low temperatures which showed the strongest P3HT interchain π-π-ordering along the substrate surface. By adding the "unfriendly" solvent cyclohexanone to a chlorobenzene solution of P3HT:PCBM, the solubility can be crossed prior to the drying process. Such solutions exhibit randomly orientated crystalline structures in the freshly cast film which results in a large crystalline orientation distribution in the dry film that has been shown to be beneficial for solar cell performance.

  20. Polymer blends of polylactic acid (PLA) and polybutylene succinate-adipate

    NASA Astrophysics Data System (ADS)

    Ma, Wenguang

    A series of blends consisting of polylactic acid (PLA) and aliphatic succinate polyester (BionolleRTM #3000) had been prepared and investigated. The results of mechanical property investigations showed that using 20 wt% Bionolle#3000 can significantly increase the toughness of PLA. BionolleRTM #3000 also reduces the physical aging rate of PLA so blends remain tough longer. Conversely, the stiffness of BionolleRTM #3000 can be significantly increased by blending in PLA. DMA and DSC results show that PLA/BionolleRTM 3000 blends are not thermodynamically miscible, but are compatible blends. Studies have also been performed to determine the amount and rate of aerobic biodegradation of PLA/aliphatic succinate polyester blends in biologically active composting, enzymatic, and soil environments. The changes in molecular weight, molecular structure and thermal properties in the composting environment were also studied by GPC, NMR and DSC analyses. The research results showed BionolleRTM #3000 had a high degradation rate, while PLA had a low degradation rate. PLA/BionolleRTM #3000 blends had moderate degradation rates that increased with BionolleRTM #3000 content. The melt flow behavior of PLA/BionolleRTM #3000 blends has been studied by capillary rheometry. The relationship of the blends' viscosity with their composition, shear stress, shear rate, and temperature has been investigated. Power law index and activation energy of PLA, BionolleRTM #3000 and their blends have been calculated. The experimental and theoretical data can let us understand the processability of PLA/BionolleRTM #3000 blends. A scanning electron microscope (SEM) was used to investigate the morphological structure of the PLA/BionolleRTM #3000 blends. Micrographs of the samples made from different methods (blown film, extrudate and compression molding sheet) were taken; their differences in morphology were compared. For comparison, the micrographs of blend PLA/BionolleRTM #6000 was also studied. The

  1. Residual solvent content in conducting polymer-blend films mapped with scanning transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Meier, Robert; Schindler, Markus; Müller-Buschbaum, Peter; Watts, Benjamin

    2011-11-01

    Near-edge x-ray absorption fine-structure spectra prove the presence of solvent molecules in conducting polymer films and are used to calculate the absolute solvent uptake of, e.g., 5 vol.% in poly(vinylcarbazole) (PVK) films, which were prepared by solution casting with cyclohexanone as solvent. Nanoscale scanning transmission x-ray microscopy (STXM) reveals a thickness-independent solvent content in a PVK gradient sample due to the formation of an enrichment layer of residual solvent. In polymer-blend films of PVK and poly(3-hexylthiophene) (P3HT), STXM probes a lateral residual solvent uptake, which depends on the composition of the phase-separation domains. For all measurements, oxygen-containing solvent molecules in oxygen-free conducting polymer films are used as marker material, and a significant amount of residual solvent is found in all types of investigated samples.

  2. Solid state double layer capacitor based on a polyether polymer electrolyte blend and nanostructured carbon black electrode composites

    NASA Astrophysics Data System (ADS)

    Lavall, Rodrigo L.; Borges, Raquel S.; Calado, Hállen D. R.; Welter, Cezar; Trigueiro, João P. C.; Rieumont, Jacques; Neves, Bernardo R. A.; Silva, Glaura G.

    An all solid double layer capacitor was assembled by using poly(ethylene oxide)/poly(propylene glycol)- b-poly(ethylene glycol)- b-poly(propylene glycol)-bis(2-aminopropyl ether) blend (PEO-NPPP) and LiClO 4 as polymer electrolyte layer and PEO-NPPP-carbon black (CB) as electrode film. High molecular weight PEO and the block copolymer NPPP with molecular mass of 2000 Da were employed, which means that the design is safe from the point of view of solvent or plasticizer leakage and thus, a separator is not necessary. Highly conductive with large surface area nanostructured carbon black was dispersed in the polymer blend to produce the electrode composite. The electrolyte and electrode multilayers prepared by spray were studied by differential scanning calorimetry, atomic force microscopy (AFM) and impedance spectroscopy. The ionic conductivity as a function of temperature was fitted with the Williams-Landel-Ferry equation, which indicates a conductivity mechanism typical of solid polymer electrolyte. AFM images of the nanocomposite electrode showed carbon black particles of approximately 60 nm in size well distributed in a semicrystalline and porous polymer blend coating. The solid double layer capacitor with 10 wt.% CB was designed with final thickness of approximately 130 μm and delivered a capacitance of 17 F g -1 with a cyclability of more than 1000 cycles. These characteristics make possible the construction of a miniature device in complete solid state which will avoid electrolyte leakage and present a performance superior to other similar electric double layer capacitors (EDLCs) presented in literature, as assessed in specific capacitance by total carbon mass.

  3. Preferential interactions in pigmented, polymer blends - C.I. Pigment Blue 15:4 and C.I. Pigment Red 122 - as used in a poly(carbonate)-poly(butylene terephthalate) polymer blend.

    PubMed

    Fagelman, K E; Guthrie, J T

    2005-11-18

    Some important characteristics of selected pigments have been evaluated, using the inverse gas chromatography (IGC) technique, that indicate the occurrence of preferential interactions in pigmented polymer blends. Attention has been given to copper phthalocyanine pigments and to quinacridone pigments incorporated in polycarbonate-poly(butylene terephthalate) blends. Selected supporting techniques were used to provide supplementary information concerning the pigments of interest, C.I. Pigment Blue 15:4 and C.I. Pigment Red 122. For C.I. Pigment Red 122 and for C.I. Pigment Blue, the dispersive component of the surface free energy decreases as the temperature increases, indicating the relative ease with which the molecules can be removed from the surface.

  4. Comment on ``Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends'' [J. Chem. Phys. 138, 054903 (2013)

    NASA Astrophysics Data System (ADS)

    Colmenero, J.

    2013-05-01

    In a recent paper by Ngai and Capaccioli ["Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends," J. Chem. Phys. 138, 054903 (2013), 10.1063/1.4789585] the authors claimed that the so-called coupling model (CM) provides a unified explanation of all dynamical anomalies that have been reported for dynamically asymmetric blends over last ten years. Approximately half of the paper is devoted to chain-dynamic properties involving un-entangled polymers. According to the authors, the application of the CM to these results is based on the existence of a crossover at a time tc ≈ 1-2 ns of the magnitudes describing chain-dynamics. Ngai and Capaccioli claimed that the existence of such a crossover is supported by the neutron scattering and MD-simulation results, corresponding to the blend poly(methyl methacrylate)/poly(ethylene oxide), by Niedzwiedz et al. [Phys. Rev. Lett. 98, 168301 (2007), 10.1103/PhysRevLett.98.168301] and Brodeck et al. [Macromolecules 43, 3036 (2010), 10.1021/ma902820a], respectively. Being one of the authors of these two papers, I will demonstrate here that there is no evidence supporting such a crossover in the data reported in these papers.

  5. Development and Experimental Validation of Morphology Predictive Model for Compatibilized Ternary Polymer Blends I. Effect of Interfacial Tension

    NASA Astrophysics Data System (ADS)

    Shokoohi, Shirin; Naderi, Ghasem

    2016-01-01

    To evaluate the prediction reliability of conventional morphology predicting models, polypropylene (PP)/polyamide6 (PA6)/ethylene propylene diene monomer (EPDM) (70/15/15) ternary polymer blends compatibilized with Maleic-anhydride grafted EPDM (EPDM-g-MA) were prepared through melt blending using a twin screw extruder (TSE). Different EPDM/EPDM-g-MA ratios i.e. 100/0, 75/25, 50/50, 25/75 and 0/100 were used to prepare the ternery blend PP/(EPDM-g-MA + EPDM)/PA6 samples. The effects of compatibilizer content on the microstructures and consequently mechanical properties of prepared ternary blends were studied. Direct microstructural observations were compared to the predictions of conventional phenomenological models including spreading coefficient, minimum relative free energy, and dynamic interfacial energy. A comparison depicted the relative inaccuracy of the existing models in predicting the morphology of the present ternary system due to the ignorance of some effective parameters and/or discomfit of model assumptions. A novel predictive model was developed considering parameters ignored in conventional models. A thorough investigation of the model's validation results showed a reasonable agreement between model predictions and direct microstructural observations.

  6. Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends.

    PubMed

    Campoy-Quiles, Mariano; Ferenczi, Toby; Agostinelli, Tiziano; Etchegoin, Pablo G; Kim, Youngkyoo; Anthopoulos, Thomas D; Stavrinou, Paul N; Bradley, Donal D C; Nelson, Jenny

    2008-02-01

    Control of blend morphology at the microscopic scale is critical for optimizing the power conversion efficiency of plastic solar cells based on blends of conjugated polymer with fullerene derivatives. In the case of bulk heterojunctions of regioregular poly(3-hexylthiophene) (P3HT) and a soluble fullerene derivative ([6,6]-phenyl C61-butyric acid methyl ester, PCBM), both blend morphology and photovoltaic device performance are influenced by various treatments, including choice of solvent, rate of drying, thermal annealing and vapour annealing. Although the protocols differ significantly, the maximum power conversion efficiency values reported for the various techniques are comparable (4-5%). In this paper, we demonstrate that these techniques all lead to a common arrangement of the components, which consists of a vertically and laterally phase-separated blend of crystalline P3HT and PCBM. We propose a morphology evolution that consists of an initial crystallization of P3HT chains, followed by diffusion of PCBM molecules to nucleation sites, at which aggregates of PCBM then grow.

  7. Improved electrical properties of Fe nanofiller impregnated PEO + PVP:Li+ blended polymer electrolytes for lithium battery applications

    NASA Astrophysics Data System (ADS)

    Naveen Kumar, K.; Saijyothi, K.; Kang, Misook; Ratnakaram, Y. C.; Hari Krishna, K.; Jin, Dahee; Lee, Yong Min

    2016-07-01

    Solid polymer-blended electrolyte films of polyethylene oxide (PEO) + polyvinyl pyrrolidone (PVP)/lithium perchlorate embedded with iron (Fe) nanofiller in different concentrations have been synthesized by a solution casting method. The semicrystalline nature of these polymer electrolyte films has been confirmed from their XRD profiles. Polymer complex formation and ion-polymer interactions are systematically studied by FTIR and laser Raman spectral analysis. Surface morphological studies are carried out from SEM analysis. Dispersed Fe nanofiller size evaluation study has been carried out using transmission electron microscopy (TEM). In order to evaluate the thermal stability, decomposition temperature, and thermogravimetric dynamics, we carried out the TG/DTA measurement. Upon addition of Fe nanofiller to the PEO + PVP/Li+ electrolyte system, it was found to result in the enhancement of ionic conductivity. The maximum ionic conductivity has been set up to be 1.14 × 10-4 Scm-1 at the optimized concentration of 4 wt% Fe nanofiller-embedded PEO + PVP/Li+ polymer electrolyte nanocomposite at an ambient temperature. PEO + PVP/Li+ + Fe nanofiller (4 wt%) cell exhibited better performance in terms of cell parameters. Based on the cell parameters, the 4 wt% Fe nanofiller-dispersed PEO + PVP/Li+ polymer electrolyte system could be suggested as a perspective candidate for solid-state battery applications.

  8. Single-Junction Binary-Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency.

    PubMed

    Zhao, Fuwen; Dai, Shuixing; Wu, Yang; Zhang, Qianqian; Wang, Jiayu; Jiang, Li; Ling, Qidan; Wei, Zhixiang; Ma, Wei; You, Wei; Wang, Chunru; Zhan, Xiaowei

    2017-03-10

    A new fluorinated nonfullerene acceptor, ITIC-Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end-capping group 1,1-dicyanomethylene-3-indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push-pull effect between the donor unit indacenodithieno[3,2-b]thiophene and the acceptor unit IC due to electron-withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short-circuit current density (JSC ). On the other hand, incorporation of F would improve intermolecular interactions through CF···S, CF···H, and CF···π noncovalent interactions and enhance electron mobility, which is beneficial to enhancing JSC and fill factor. Indeed, the results show that fluorinated ITIC-Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC-Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC-Th1 electron acceptor and a wide-bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC-Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene-based single-junction binary-blend OSCs. Moreover, the OSCs based on FTAZ:ITIC-Th1 show much better efficiency and better stability than the control devices based on FTAZ:PC71 BM (PCE = 5.22%).

  9. Field-theoretical Renormalization-Group approach to critical dynamics of crosslinked polymer blends

    NASA Astrophysics Data System (ADS)

    Benhamou, M.; Chahid, M.

    2008-09-01

    We consider a crosslinked polymer blend that may undergo a microphase separation. When the temperature is changed from an initial value towards a final one very close to the spinodal point, the mixture is out equilibrium. The aim is the study of dynamics at a given time t , before the system reaches its final equilibrium state. The dynamics is investigated through the structure factor, S(q, t) , which is a function of the wave vector q , temperature T , time t , and reticulation dose D . To determine the phase behavior of this dynamic structure factor, we start from a generalized Langevin equation (model C) solved by the time composition fluctuation. Beside the standard de Gennes Hamiltonian, this equation incorporates a Gaussian local noise, ζ . First, by averaging over ζ , we get an effective Hamiltonian. Second, we renormalize this dynamic field theory and write a Renormalization-Group equation for the dynamic structure factor. Third, solving this equation yields the behavior of S(q, t) , in space of relevant parameters. As result, S(q, t) depends on three kinds of lengths, which are the wavelength q-1, a time length scale R(t) thicksim t1/z , and the mesh size ξ* . The scale R(t) is interpreted as the size of growing microdomains at time t . When R(t) becomes of the order of ξ* , the dynamics is stopped. The final time, t * , then scales as t * thicksim ξ{ast z} , with the dynamic exponent z = 6 - η . Here, η is the usual Ising critical exponent. Since the final size of microdomains ξ* is very small (few nanometers), the dynamics is of short time. Finally, all these results we obtained from renormalization theory are compared to those we stated in some recent work using a scaling argument.

  10. Hydrogenation with monolith reactor under conditions of immiscible liquid phases

    DOEpatents

    Nordquist, Andrew Francis; Wilhelm, Frederick Carl; Waller, Francis Joseph; Machado, Reinaldo Mario

    2002-01-01

    The present invention relates to an improved for the hydrogenation of an immiscible mixture of an organic reactant in water. The immiscible mixture can result from the generation of water by the hydrogenation reaction itself or, by the addition of, water to the reactant prior to contact with the catalyst. The improvement resides in effecting the hydrogenation reaction in a monolith catalytic reactor from 100 to 800 cpi, at a superficial velocity of from 0.1 to 2 m/second in the absence of a cosolvent for the immiscible mixture. In a preferred embodiment, the hydrogenation is carried out using a monolith support which has a polymer network/carbon coating onto which a transition metal is deposited.

  11. Investigation of miscibility of p(3hydroxybutyrate-co-3hydroxyhexanoate) and epoxidized natural rubber blends

    SciTech Connect

    Akram, Faridah; Chan, Chin Han; Natarajan, Valliyappan David

    2015-08-28

    Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate [P(3HB-co-3HHx)] produced by C. necator PHB{sup −}4 harboring phaC{sub cs} from crude palm kernel oil with 21 mol% of 3-hydroxyhexanoate and epoxidized natural rubber with 25 mol% of epoxy content (ENR-25) were used to study the miscibility of the blends by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and differential scanning calorimetry (DSC). The polymers used were purified and the blends were prepared by solution casting method. Nuclear magnetic resonance (NMR) spectra confirm the purity and molecular structures of P(3HB-co-3HHx) and ENR-25. FTIR spectra for different compositions of P(3HB-co-3HHx) and ENR-25 blends show absorbance change of the absorbance bands but with no significant shifting of the absorbance bands as the P(3HB-co-3HHx) content decreases, which shows that there is no intermolecular interaction between the parent polymer blends. On top of that, there are two T{sub g}s present for the blends and both remain constant for different compositions which corresponds to the T{sub g}s of the parent polymers. This indicates that the blends are immiscible.

  12. Investigation of miscibility of p(3hydroxybutyrate-co-3hydroxyhexanoate) and epoxidized natural rubber blends

    NASA Astrophysics Data System (ADS)

    Akram, Faridah; Chan, Chin Han; Natarajan, Valliyappan David

    2015-08-01

    Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate [P(3HB-co-3HHx)] produced by C. necator PHB-4 harboring phaCcs from crude palm kernel oil with 21 mol% of 3-hydroxyhexanoate and epoxidized natural rubber with 25 mol% of epoxy content (ENR-25) were used to study the miscibility of the blends by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and differential scanning calorimetry (DSC). The polymers used were purified and the blends were prepared by solution casting method. Nuclear magnetic resonance (NMR) spectra confirm the purity and molecular structures of P(3HB-co-3HHx) and ENR-25. FTIR spectra for different compositions of P(3HB-co-3HHx) and ENR-25 blends show absorbance change of the absorbance bands but with no significant shifting of the absorbance bands as the P(3HB-co-3HHx) content decreases, which shows that there is no intermolecular interaction between the parent polymer blends. On top of that, there are two Tgs present for the blends and both remain constant for different compositions which corresponds to the Tgs of the parent polymers. This indicates that the blends are immiscible.

  13. Crystalline-amorphous interaction in relation to the phase diagrams of binary polymer blends containing a crystalline constituent.

    PubMed

    Rathi, Pankaj; Huang, Tsang-Min; Dayal, Pratyush; Kyu, Thein

    2008-05-22

    The present article describes an equilibrium theory for determining binary phase diagrams of various crystalline-amorphous polymer blends by taking into account the contributions from both liquid-liquid phase separation between the constituents and solid-liquid phase transition of the crystalline component. An analytical expression for determining a crystal-amorphous interaction parameter is deduced based on the solid-liquid transition, involving the solidus and liquidus lines in conjunction with the coexistence curve of an upper critical solution temperature type. Of particular importance is that the crystalline-amorphous interaction parameter can be determined directly from the melting point depression data. The present analysis is therefore different from the conventional Flory-Huggins interaction parameter, which is associated with the liquid-liquid phase separation. The validity of the present theory is tested with the experimental phase diagrams of blends of poly(ethylene oxide)/diacrylate and poly(vinyl alcohol)/cellulose.

  14. Spectroscopic analysis and mechanical properties of electron beam irradiated polypropylene/epoxidized natural rubber (PP/ENR) polymer blends

    NASA Astrophysics Data System (ADS)

    Senna, Magdy M. H.; Abdel-Fattah, Atef A.; Abdel-Monem, Y. K.

    2008-06-01

    Polymer blends based on different ratios of polypropylene (PP) and epoxidized natural rubber (ENR) were prepared by melt extrusion into sheets. The PP/ENR blends were exposed to various dose of accelerated electrons. The formation of free radicals during and after electron beam irradiation was illustrated by electron spin resonance (ESR). Also, the effect of electron beam irradiation on the mechanical and structural morphology was investigated by stress-strain behavior and scanning electron microscope (SEM). The ESR spectra indicated the formation of alkyl and allyl radicals during electron beam irradiation and peroxyl radicals during the post effect. The rate of radical decay was found to be second-order kinetics. The improvement in mechanical properties and structural morphology was confirmed to be due to the effect of electron beam irradiation.

  15. Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

    NASA Astrophysics Data System (ADS)

    Dinesh, Meghala; Chikkakuntappa, Ranganathaiah

    2013-09-01

    Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (αij) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from -3.18 to -4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from -3.81 to -7.57 at composition 20/50/30 after irradiation.

  16. Blended nanoparticle system based on miscible structurally similar polymers: a safe, simple, targeted, and surprisingly high efficiency vehicle for cancer therapy.

    PubMed

    Tao, Wei; Zhang, Jinxie; Zeng, Xiaowei; Liu, Danny; Liu, Gan; Zhu, Xi; Liu, Yanlan; Yu, Qingtong; Huang, Laiqiang; Mei, Lin

    2015-06-03

    A novel blended nanoparticle (NP) system for the delivery of anticancer drugs and its surprisingly high efficacy for cancer chemotherapy by blending a targeting polymer folic acid-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (FA-PEG-b-PLGA) and a miscible structurally similar polymer D-α-tocopheryl polyethylene glycol 1000 succinate-poly(lactide-co-glycolide) (TPGS-PLGA) is reported. This blended NP system can be achieved through a simple and effective nanoprecipitation technique, and possesses unique properties: i) improved long-term compatibility brought by PEG-based polymers; ii) reduced multidrug resistance mediated by P-glycoprotein (P-gp) in tumor cells and increased bioavailability of anticancer drugs by incorporation of TPGS; iii) the regulation of controlled release through polymer ratios and active targeting by FA. Both in vitro cell experiments and in vivo antitumor assays demonstrated the reported blended NP system can achieve the best therapeutic efficiency in an extremely safe, simple and highly efficient process for cancer therapy. Moreover, this NP system is highly efficient in forming NPs with multiple functions, without repeated chemical modification of polymers, which is sometimes complex, inefficient and high cost. Therefore, the development of this novel blended NP concept is extremely meaningful for the application of pharmaceutical nanotechnology in recent studies.

  17. Performance of polymer electrolyte based on chitosan blended with poly(ethylene oxide) for plasmonic dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Buraidah, M. H.; Teo, L. P.; Au Yong, C. M.; Shah, Shahan; Arof, A. K.

    2016-07-01

    Chitosan and poly(ethylene oxide) powders have been mixed in different weight ratios. To each mixture, a fixed amount of ammonium iodide has been added. All mixtures have been dissolved in 1% acetic acid solution to form polymer blend electrolyte films by the solution cast technique. X-ray diffraction indicates that the polymer blend electrolytes are amorphous. Fourier transform infrared spectroscopy shows shifting of the amine, carboxamide and Csbnd Osbnd C bands to lower wavenumbers indicating the occurrence of complexation. Electrochemical impedance spectroscopy has been used to study the electrical properties of the samples. The ionic conductivity for 55 wt.% chitosan-45 wt.% NH4I electrolyte system is 3.73 × 10-7 S cm-1 at room temperature and is increased to 3.66 × 10-6 S cm-1 for the blended film (16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I film. Dye-sensitized solar cells (DSSCs) have been fabricated by sandwiching the polymer electrolyte between the TiO2/dye photoelectrode and Pt counter electrode. DSSCs fabricated exhibits short-circuit current density (Jsc) of 2.71 mA cm-2, open circuit voltage (Voc) of 0.58 V and efficiency of 0.78% with configuration ITO/TiO2/N3 dye/(16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I(+I2)/Pt/ITO and Jsc of 2.84 mA cm-2, Voc of 0.58 V and efficiency of 1.13% with configuration ITO/TiO2 + Ag nanoparticles/N3 dye/(16.5 wt.% chitosan-38.5 wt.% PEO)-45 wt.% NH4I(+I2)/Pt/ITO.

  18. Influence of Surface Energy on Organic Alloy Formation in Ternary Blend Solar Cells Based on Two Donor Polymers.

    PubMed

    Gobalasingham, Nemal S; Noh, Sangtaik; Howard, Jenna B; Thompson, Barry C

    2016-10-05

    The compositional dependence of the open-circuit voltage (Voc) in ternary blend bulk heterojunction (BHJ) solar cells is correlated with the miscibility of polymers, which may be influenced by a number of attributes, including crystallinity, the random copolymer effect, or surface energy. Four ternary blend systems featuring poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) (P3HT75-co-EHT25), poly(3-hexylthiophene-co-(hexyl-3-carboxylate)), herein referred to as poly(3-hexylthiophene-co-3-hexylesterthiophene) (P3HT50-co-3HET50), poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP-10%), and an analog of P3HTT-DPP-10% with 40% of 3-hexylthiophene exchanged for 2-(2-methoxyethoxy)ethylthiophen-2-yl (3MEO-T) (featuring an electronically decoupled oligoether side-chain), referred to as P3HTTDPP-MEO40%, are explored in this work. All four polymers are semicrystalline and rich in rr-P3HT content and perform well in binary devices with PC61BM. Except for P3HTTDPP-MEO40%, all polymers exhibit similar surface energies (∼21-22 mN/m). P3HTTDPP-MEO40% exhibits an elevated surface energy of around 26 mN/m. As a result, despite the similar optoelectronic properties and binary solar cell performance of P3HTTDPP-MEO40% compared to P3HTT-DPP-10%, the former exhibits a pinned Voc in two different sets of ternary blend devices. This is a stark contrast to previous rr-P3HT-based systems and demonstrates that surface energy, and its influence on miscibility, plays a critical role in the formation of organic alloys and can supersede the influence of crystallinity, the random copolymer effect, similar backbone structures, and HOMO/LUMO considerations. Therefore, we confirm surface energy compatibility as a figure-of-merit for predicting the compositional dependence of the Voc in ternary blend solar cells and highlight the importance of polymer miscibility in organic alloy formation.

  19. Ultrasonic studies on polystyrene/styrene butadiene rubber polymer blends filled with glass fiber and talc.

    PubMed

    Higazy, A A; Afifi, H; Khafagy, A H; El-Shahawy, M A; Mansour, A M

    2006-12-22

    The compatibility of solid blends: PS/SBR, PS/SBR filled with glass fiber and PS/SBR filled with talc were studied using ultrasonic pulse echo technique. Measurements were carried out at room temperature (298 K) and a frequency of 3 MHz. The ultrasonic velocity for the compressional wave and that for shear wave have been measured to obtain the elastic moduli data by knowing of density. The variation of ultrasonic wave velocities and elastic moduli with weight percent of the blend was found to be linear in PS/SBR blend, indicating some degree of compatibility but the drawback of elastic moduli indicate incompatibility of the system blend, while it deviates from linearity in blends of PS/SBR filled with glass fiber and talc but the increase in elastic moduli indicates that there is an increase in degree of compatibility between PS and SBR due to adding of glass fiber or talc. The ultrasonic absorptions for longitudinal wave in the temperature range from 298 to 423 K in the studied system were measured using ultrasonic pulse echo technique. Typical results showing the temperature dependence of the ultrasonic absorption at frequencies of 1, 2, 3 and 5 MHz are illustrated for all samples of the different compositions. The study of compositional and temperature dependence of the ultrasonic absorption in the present studied blends reveals the same behavior of the compatibility degree of the blends. Density data of the blends confirmed the ultrasonic results. Also the correlation between hardness and elastic moduli for the present blend systems has been studied.

  20. Effect of Complexation of NaCl Salt with Polymer Blend (PEO/PVP) Electrolytes on Ionic Conductivity and Optical Energy Band Gaps

    NASA Astrophysics Data System (ADS)

    Kumar, K. Kiran; Pavani, Y.; Ravi, M.; Bhavani, S.; Sharma, A. K.; Rao, V. V. R. Narasimha

    2011-10-01

    Sodium ion conducting polymer blend electrolyte films, based on polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with NaCl salt, were prepared using solution casting technique. The complexation of the salt with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-vis spectroscopy. Frequency and temperature dependence of electrical conductivity of the films was studied with impedance analyzer in the frequency range of 1 Hz to 1 MHz and in the temperature range of 303-348 K. UV-vis absorption spectra in wavelength region 200-800 nm, were used to evaluate the optical properties like direct and indirect optical energy band gaps, optical absorption edge. The optical band gaps decreased with the increase of Na+ ion concentration. This suggests that NaCl, as dopant, is a good choice to improve the electrical and optical properties of PEO/PVP polymer blend electrolytes.

  1. Enhanced light out-coupling of OLEDs with low haze by inserting randomly dispersed nanopillar arrays formed by lateral phase separation of polymer blends.

    PubMed

    Lee, Cholho; Kim, Jang-Joo

    2013-11-25

    A simple and efficient method to fabricate light extraction layers is demonstrated by utilizing the phase separation of two polymer blends to enhance the light out-coupling efficiency of OLEDs with low haze. Polystyrene and poly(methyl methacrylate) dissolved in tetrahydrofuran are mixed and spin-coated over ITO-coated glass substrates. Nanopores and nanopillar arrays are formed through lateral phase separation of the polymer blend. The shape, size, and distribution of the patterns can be controlled through changes in the composition and thickness of the coated polymer blends. Phosphorescent OLEDs are fabricated using randomly dispersed nanopillar arrays as light extraction layers and they show a 24% enhancement in external quantum efficiency with a Lambertian emission pattern, no spectrum dependence on viewing angles, and only a small increment in the haze. With these advantages, this newly developed method can be adapted to be used for large-area, flexible substrates for lighting and display applications.

  2. Organic Thin-Film Transistors with Phase Separation of Polymer-Blend Small-Molecule Semiconductors: Dependence on Molecular Weight and Types of Polymer

    NASA Astrophysics Data System (ADS)

    Ohe, Takahiro; Kuribayashi, Miki; Tsuboi, Ami; Satori, Kotaro; Itabashi, Masao; Nomoto, Kazumasa

    2009-12-01

    We have investigated effect of polymer on solution-processed organic thin-film transistors (TFTs) with polymer-blend semiconductors. Organic TFTs made from a solution of 6,13-bis(triisopropylsilylethynyl)-pentacene with a poly(α-methylstyrene) (PaMS) molecular weight of 20 k or above, exhibited mobility around 0.1 cm2/(V.s). On the other hand, the organic TFTs with a PaMS molecular weight of 2 k or with a poly(isobutyl methacrylate), exhibited much lower mobility. This can be explained in terms of the structure and crystallinity of the films. The results of film structure can be explained by applying the Flory-Huggins theory.

  3. Influence of Al2O3 on the ionic conductivity of plasticized PVC-PEG blend polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Ravindran, D.; Vickraman, P.

    2016-05-01

    Polymer electrolytes with PVC-PEG blend as host matrix and LiClO4 as dopant salt was prepared through conventional solution casting method. To enhance the conductivity propylene carbonate (PC) was used as plasticizer. The influence of ceramic filler Al2O3 on the conductivity of the electrolyte films were studied by varying the (PVC: Al2O3) ratio. The films were subjected to XRD, complex impedance analysis and SEM analysis. The XRD studies reveal a marginal increase in the amorphous phase of the electrolyte films due to the incorporation of filler. The AC impedance analysis shows the dependency of ionic conductivity on the content (wt %) of filler and exhibit a maximum at 4 wt% filler. The SEM analysis depicts the occurrence of phase separation in electrolyte which is attributed to the poor solubility of polymer PVC in the liquid electrolyte.

  4. SOLUTION RHEOLOGY OF HYPERBRANCHED POLYESTERS AND THEIR BLENDS WITH LINEAR POLYMERS

    EPA Science Inventory

    In this study, the rheological properties of different generations of hyperbranched polyesters in 1-methyl-2-pyrrolidinone solvent and their blends with poly(2-hydroxyethyl methacrylate) have ben investigated. All the hyperbranched polyester solutions exhibited Newtonian behavior...

  5. Prediction of dexamethasone release from PLGA microspheres prepared with polymer blends using a design of experiment approach.

    PubMed

    Gu, Bing; Burgess, Diane J

    2015-11-10

    Hydrophobic drug release from poly (lactic-co-glycolic acid) (PLGA) microspheres typically exhibits a tri-phasic profile with a burst release phase followed by a lag phase and a secondary release phase. High burst release can be associated with adverse effects and the efficacy of the formulation cannot be ensured during a long lag phase. Accordingly, the development of a long-acting microsphere product requires optimization of all drug release phases. The purpose of the current study was to investigate whether a blend of low and high molecular weight polymers can be used to reduce the burst release and eliminate/minimize the lag phase. A single emulsion solvent evaporation method was used to prepare microspheres using blends of two PLGA polymers (PLGA5050 (25 kDa) and PLGA9010 (113 kDa)). A central composite design approach was applied to investigate the effect of formulation composition on dexamethasone release from these microspheres. Mathematical models obtained from this design of experiments study were utilized to generate a design space with maximized microsphere drug loading and reduced burst release. Specifically, a drug loading close to 15% can be achieved and a burst release less than 10% when a composition of 80% PLGA9010 and 90 mg of dexamethasone is used. In order to better describe the lag phase, a heat map was generated based on dexamethasone release from the PLGA microsphere/PVA hydrogel composite coatings. Using the heat map an optimized formulation with minimum lag phase was selected. The microspheres were also characterized for particle size/size distribution, thermal properties and morphology. The particle size was demonstrated to be related to the polymer concentration and the ratio of the two polymers but not to the dexamethasone concentration.

  6. Aesthetically pleasing conjugated polymer:fullerene blends for blue-green solar cells via roll-to-roll processing.

    PubMed

    Amb, Chad M; Craig, Michael R; Koldemir, Unsal; Subbiah, Jegadesan; Choudhury, Kaushik Roy; Gevorgyan, Suren A; Jørgensen, Mikkel; Krebs, Frederik C; So, Franky; Reynolds, John R

    2012-03-01

    The practical application of organic photovoltaic (OPV) cells requires high throughput printing techniques in order to attain cells with an area large enough to provide useful amounts of power. However, in the laboratory screening of new materials for OPVs, spin-coating is used almost exclusively as a thin-film deposition technique due its convenience. We report on the significant differences between the spin-coating of laboratory solar cells and slot-die coating of a blue-green colored, low bandgap polymer (PGREEN). This is one of the first demonstrations of slot-die-coated polymer solar cells OPVs not utilizing poly(3-hexylthiophene):(6,6)-phenyl-C(61)-butyric acid methyl ester (PCBM) blends as a light absorbing layer. Through synthetic optimization, we show that strict protocols are necessary to yield polymers which achieve consistent photovoltaic behavior. We fabricated spin-coated laboratory scale OPV devices with PGREEN: PCBM blends as active light absorbing layers, and compare performance to slot die-coated individual solar cells, and slot-die-coated solar modules consisting of many cells connected in series. We find that the optimum ratio of polymer to PCBM varies significantly when changing from spin-coating of thinner active layer films to slot-die coating, which requires somewhat thicker films. We also demonstrate the detrimental impacts on power conversion efficiency of high series resistance imparted by large electrodes, illustrating the need for higher conductivity contacts, transparent electrodes, and high mobility active layer materials for large-area solar cell modules.

  7. Morphological characterization of bicontinuous structures in polymer blends and microemulsions by the inverse-clipping method in the context of the clipped-random-wave model.

    PubMed

    Jinnai, H; Nishikawa, Y; Chen, S H; Koizumi, S; Hashimoto, T

    2000-06-01

    A method is proposed to determine the spectral function of the clipped-random-wave (CRW) model directly from scattering data. The spectral function f(k) (k is a wave number) gives the distribution of the magnitude of wave vectors of the sinusoidal waves that describes the essential features of the two-phase morphology. The proposed method involves "inverse clipping" of a correlation function to obtain f(k) and does not require any a priori assumptions for f(k). A critical test of the applicability of the inverse-clipping method was carried out by using three-component bicontinuous microemulsions. The method was then used to determine f(k) of the bicontinuous structure of a phase-separating polymer blend. f(k) for the polymer blend turned out to be a multipeaked function, while f(k) for the microemulsions exhibits a single broad maximum representing periodicity of the morphology. These results indicate the presence of the long-range regularity in the morphology of the polymer blend. Three-dimensional (3D) morphology corresponding to the scattering data of the polymer blend was generated using the CRW model together with the multipeaked f(k). Interface curvatures of the 3D morphology calculated from f(k) were measured and compared with those experimentally determined directly from the laser scanning confocal microscopy in the same blend.

  8. Morphological characterization of bicontinuous structures in polymer blends and microemulsions by the inverse-clipping method in the context of the clipped-random-wave model

    NASA Astrophysics Data System (ADS)

    Jinnai, Hiroshi; Nishikawa, Yukihiro; Chen, Sow-Hsin; Koizumi, Satoshi; Hashimoto, Takeji

    2000-06-01

    A method is proposed to determine the spectral function of the clipped-random-wave (CRW) model directly from scattering data. The spectral function f(k) (k is a wave number) gives the distribution of the magnitude of wave vectors of the sinusoidal waves that describes the essential features of the two-phase morphology. The proposed method involves ``inverse clipping'' of a correlation function to obtain f(k) and does not require any a priori assumptions for f(k). A critical test of the applicability of the inverse-clipping method was carried out by using three-component bicontinuous microemulsions. The method was then used to determine f(k) of the bicontinuous structure of a phase-separating polymer blend. f(k) for the polymer blend turned out to be a multipeaked function, while f(k) for the microemulsions exhibits a single broad maximum representing periodicity of the morphology. These results indicate the presence of the long-range regularity in the morphology of the polymer blend. Three-dimensional (3D) morphology corresponding to the scattering data of the polymer blend was generated using the CRW model together with the multipeaked f(k). Interface curvatures of the 3D morphology calculated from f(k) were measured and compared with those experimentally determined directly from the laser scanning confocal microscopy in the same blend.

  9. Mechanical characterization and modelling of the temperature-dependent impact behaviour of a biocompatible poly(L-lactide)/poly(ε-caprolactone) polymer blend.

    PubMed

    Gustafsson, Gustaf; Nishida, Masahiro; Ito, Yoshitaka; Häggblad, Hans-Åke; Jonsén, Pär; Takayama, Tetsuo; Todo, Mitsugu

    2015-11-01

    Poly(ε-caprolactone) (PCL) is a ductile, bioabsorbable polymer that has been employed as a blend partner for poly(L-lactic acid) (PLLA). An improvement of the material strength and impact resistance of PLLA/PCL polymer blends compared to pure PLLA has been shown previously. To use numerical simulations in the design process of new components composed of the PLLA/PCL blend, a constitutive model for the material has to be established. In this work, a constitutive model for a PLLA/PCL polymer blend is established from the results of compressive tests at high and low strain rates at three different temperatures, including the body temperature. Finite element simulations of the split Hopkinson pressure bar test using the established constitutive model are carried out under the same condition as the experiments. During the experiments, the changes in the diameter and thickness of the specimens are captured by a high-speed video camera. The accuracy of the numerical model is tested by comparing the simulation results, such as the stress, strain, thickness and diameter histories of the specimens, with those measured in the experiments. The numerical model is also validated against an impact test of non-homogenous strains and strain rates. The results of this study provide a validated numerical model for a PLLA/PCL polymer blend at strain rates of up to 1800 s(-1) in the temperature range between 22°C and 50°C.

  10. Synthetic polymers blend used in the production of high activated carbon for pesticides removals from liquid phase.

    PubMed

    Belo, Cristóvão Ramiro; Cansado, Isabel Pestana da Paixão; Mourão, Paulo Alexandre Mira

    2017-02-01

    For the activated carbon (AC) production, we used the most common industrial and consumer solid waste, namely polyethyleneterephthalate (PET), alone or blended with other synthetic polymer such polyacrylonitrile (PAN). By mixing PET, with PAN, an improvement in the yield of the AC production was found and the basic character and some textural and chemical properties were enhanced. The PET-PAN mixture was subjected to carbonisation, with a pyrolysis yield of 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The AC revealed a high surface area (1400, 1230 and 1117 m(2) g(-1)) and pore volume (0.46, 0.56 and 0.50 cm(3) g(-1)), respectively, for PET, PAN and PET-PAN precursors. Selected ACs were successfully tested for 4-chloro-2-methylphenoxyacetic acid (MCPA) and diuron removal from the liquid phase, showing a higher adsorption capacity (1.7 and 1.2 mmol g(-1), respectively, for MCPA and diuron) and good fits with the Langmuir (PET) and Freundlich equation (PAN and PET-PAN blend). With MCPA, the controlling factor to the adsorption capacity was the porous volume and the average pore size. Concerning diuron, the adsorption was controlled essentially by the external diffusion. A remarkable result is the use of different synthetic polymers wastes, as precursors for the production of carbon materials, with high potential application on the pesticides removals from the liquid phase.

  11. Anomalous negative electrocaloric effect in a relaxor/normal ferroelectric polymer blend with controlled nano- and meso-dipolar couplings

    NASA Astrophysics Data System (ADS)

    Qian, Xiaoshi; Yang, Tiannan; Zhang, Tian; Chen, Long-Qing; Zhang, Q. M.

    2016-04-01

    In general, a dielectric material will eject (or absorb) heat when an electric field is applied and absorb (or eject) heat when the field is removed, under isothermal condition, which is known as the normal (or negative) electrocaloric (EC) effect. For some applications, it is highly desired that an EC material will absorb heat (cooling the surrounding) without subsequent heating under an electric pulse. Here, we show that such an EC material can be realized in a properly designed hybrid normal ferroelectric/relaxor ferroelectric polymer blend in which the normal ferroelectric component induces dipole ordering in the relaxor polymer in the poled state, which can be switched to a de-poled state by an external field. More importantly, the de-poled state can be maintained by the relaxor component when the de-poling field is removed. Consequently, the hybrid blend exhibits a large cooling (an isothermal entropy change ΔS = 11.5 J kg-1 K-1) without the subsequent heating upon the application of an electric pulse.

  12. Processing and characterization of solid and microcellular biobased and biodegradable PHBV-based polymer blends and composites

    NASA Astrophysics Data System (ADS)

    Javadi, Alireza

    Petroleum-based polymers have made a significant contribution to human society due to their extraordinary adaptability and processability. However, due to the wide-spread application of plastics over the past few decades, there are growing concerns over depleting fossil resources and the undesirable environmental impact of plastics. Most of the petroleum-based plastics are non-biodegradable and thus will be disposed in landfills. Inappropriate disposal of plastics may also become a potential threat to the environment. Many approaches, such as efficient plastics waste management and replacing petroleum-based plastics with biodegradable materials obtained from renewable resources, have been put forth to overcome these problems. Plastics waste management is at its beginning stages of development which is also more expensive than expected. Thus, there is a growing interest in developing sustainable biobased and biodegradable materials produced from renewable resources such as plants and crops, which can offer comparable performance with additional advantages, such as biodegradability, biocompatibility, and reducing the carbon footprint. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the most promising biobased and biodegradable polymers, In fact many petroleum based polymers such as poly(propylene) (PP) can be potentially replaced by PHBV because of the similarity in their properties. Despite PHBV's attractive properties, there are many drawbacks such as high cost, brittleness, and thermal instability, which hamper the widespread usage of this specific polymer. The goals of this study are to investigate various strategies to address these drawbacks, including blending with other biodegradable polymers such as poly (butylene adipate-coterephthalate) (PBAT) or fillers (e.g., coir fiber, recycled wood fiber, and nanofillers) and use of novel processing technologies such as microcellular injection molding technique. Microcellular injection molding technique

  13. Controlled endolysosomal release of agents by pH-responsive polymer blend particles

    PubMed Central

    Zhan, Xi; Tran, Kenny K.; Wang, Liguo; Shen, Hong

    2015-01-01

    Purpose A key step of delivering extracellular agents to its intracellular target is to escape from endosomal/lysosomal compartments, while minimizing the release of digestive enzymes that may compromise cellular functions. In this study, we examined the intracellular distribution of both fluorecent cargoes and enzymes by a particle delivery platform made from the controlled blending of poly (lactic-co-glycolic acid) (PLGA) and a random pH-sensitive copolymer. Methods We utilized both microscopic and biochemical methods to semi-quantitatively assess how the composition of blend particles affects the level of endosomal escape of cargos of various sizes and enzymes into the cytosolic space. Results We demonstrated that these polymeric particles enabled the controlled delivery of cargos into the cytosolic space that was more dependent on the cargo size and less on the composition of blend particles. Blend particles did not induce the rupture of endosomal/lysosomal compartments and released less than 20% of endosomal/lysosomal enzymes. Conclusions This study provides insight into understanding the efficacy and safety of a delivery system for intracellular delivery of biologics and drugs. Blend particles offer a potential platform to target intracellular compartments while potentially minimizing cellular toxicity. PMID:25592550

  14. Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation-Crosslinked Poly (Vinyl Alcohol)-Based Solid Polymer Electrolytes Blended With LiOHṡH2O Salt

    NASA Astrophysics Data System (ADS)

    Khafagy, Rasha M.; Madani, M.; Badr, Y. A.

    2008-09-01

    Solid polymer electrolytes based on poly(vinyl alcohol) (PVA) blended with different concentrations of LiOHṡH2O salt were prepared using casting and γ-irradiation techniques. The structure and blending of the poly-electrolytes were studied by X-ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and these melting points change with the salt content. All characterizing techniques revealed the blend formation between LiOHṡH2O salt and the polymer matrix. To account for the performance of the prepared solid polymer electrolytes, thermally stimulated depolarization current (TSDC) studies of the prepared blends were done. Short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm-1 have been analyzed in the temperature range 300-410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly-blend system. The prepared solid polymer electrolytes showed good charge storage capacity, and moderate current density values near the ambient.

  15. Characterisation and modelling of the thermorheological properties of pharmaceutical polymers and their blends using capillary rheometry: Implications for hot melt processing of dosage forms.

    PubMed

    Jones, David S; Margetson, Daniel N; McAllister, Mark S; Andrews, Gavin P

    2015-09-30

    Given the growing interest in thermal processing methods, this study describes the use of an advanced rheological technique, capillary rheometry, to accurately determine the thermorheological properties of two pharmaceutical polymers, Eudragit E100 (E100) and hydroxypropylcellulose JF (HPC) and their blends, both in the presence and absence of a model therapeutic agent (quinine, as the base and hydrochloride salt). Furthermore, the glass transition temperatures (Tg) of the cooled extrudates produced using capillary rheometry were characterised using Dynamic Mechanical Thermal Analysis (DMTA) thereby enabling correlations to be drawn between the information derived from capillary rheometry and the glass transition properties of the extrudates. The shear viscosities of E100 and HPC (and their blends) decreased as functions of increasing temperature and shear rates, with the shear viscosity of E100 being significantly greater than that of HPC at all temperatures and shear rates. All platforms were readily processed at shear rates relevant to extrusion (approximately 200-300 s(-1)) and injection moulding (approximately 900 s(-1)). Quinine base was observed to lower the shear viscosities of E100 and E100/HPC blends during processing and the Tg of extrudates, indicative of plasticisation at processing temperatures and when cooled (i.e. in the solid state). Quinine hydrochloride (20% w/w) increased the shear viscosities of E100 and HPC and their blends during processing and did not affect the Tg of the parent polymer. However, the shear viscosities of these systems were not prohibitive to processing at shear rates relevant to extrusion and injection moulding. As the ratio of E100:HPC increased within the polymer blends the effects of quinine base on the lowering of both shear viscosity and Tg of the polymer blends increased, reflecting the greater solubility of quinine within E100. In conclusion, this study has highlighted the importance of capillary rheometry in

  16. Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

    PubMed

    Martins, Andréa Bercini; Santana, Ruth Marlene Campomanes

    2016-01-01

    In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA.

  17. Effect of peroxide and chain extender on mechanical properties and morphology of poly (butylene succinate)/poly (lactic acid) blends

    NASA Astrophysics Data System (ADS)

    Cherykhunthod, W.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    Poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) are biodegradable polymers with high potential to replace commodity fossil-based polymers in a wide range of applications. However, these two polymers are immiscible in most ratios, but partially miscible when one of the two is a major phase. In this study, a one-step process in a twin-screw extruder was used to prepare the blends between poly (butylene succinate) (PBS) as a matrix and poly (lactic acid) (PLA) as a dispersed phase. To improve mechanical properties and morphology of blends, two reactive agents, peroxide (Perkadox) and multifunctional epoxide chain extender (Joncryl) were selected and compared. All samples were characterized for melt flow index (MFI), morphology, tensile, and impact properties. The results showed that the mechanical properties and morphology of PBS/PLA blends were improved when using both reactive agents. It was demonstrated that the increased mechanical properties resulted from good interfacial adhesion between PBS and finely dispersed PLA particles. The addition of 0.075 phr Perkadox to PBS/PLA (75:25 and 80:20) blends increased elongation at break by 7.2% and 38.4%, respectively compared with the blends without reactive agents. The results from gel content also revealed the graft copolymer existed at the interface when reactive agents were added. In the case of using multifunctional epoxide chain extender, the impact strength of the blends increased.

  18. High-performance ternary blend polymer solar cells involving both energy transfer and hole relay processes

    DOE PAGES

    Lu, Luyao; Chen, Wei; Xu, Tao; ...

    2015-06-04

    The integration of multiple materials with complementary absorptions into a single junction device is regarded as an efficient way to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs). However, because of increased complexity with one more component, only limited high-performance ternary systems have been demonstrated previously. Here we report an efficient ternary blend OSC with a PCE of 9.2%. We show that the third component can reduce surface trap densities in the ternary blend. Detailed studies unravel that the improved performance results from synergistic effects of enlarged open circuit voltage, suppressed trap-assisted recombination, enhanced light absorption, increasedmore » hole extraction, efficient energy transfer and better morphology. The working mechanism and high device performance demonstrate new insights and design guidelines for high-performance ternary blend solar cells and suggest that ternary structure is a promising platform to boost the efficiency of OSCs.« less

  19. Study of mechanical properties of polyvinyl chloride (PVC) and polystyrene (PS) polymers and their blends

    NASA Astrophysics Data System (ADS)

    Agarwal, Shalini; Saxena, N. S.; Agrawal, R.; Saraswat, Vibhav K.

    2013-06-01

    Presented work is an effort to observe the variation in mechanical properties of two thermoplastic materials PVC, PS and their blends. PVC and PS are taken in the ratio of 100:0, 70:30, 50:50, and 0:100. Mixing of PVC and PS is carried out by solution casting method using tetra hydro furan as solvent. Dynamical mechanical analyzer (DMA) is used to study mechanical properties. The storage modulus, loss modulus and mechanical loss factor (tan δ) are determined with temperature. The pallets of pure PS, PVC and their blends are scanned over a temperature range from room to 140 °C. The variation of modulus, tan δ of pure PVC & pure PS and their blends with temperature were studied. The observed variation in modulus and tan δ could be accounted for their thermal behavior and compositions.

  20. High-performance ternary blend polymer solar cells involving both energy transfer and hole relay processes

    SciTech Connect

    Lu, Luyao; Chen, Wei; Xu, Tao; Yu, Luping

    2015-06-04

    The integration of multiple materials with complementary absorptions into a single junction device is regarded as an efficient way to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs). However, because of increased complexity with one more component, only limited high-performance ternary systems have been demonstrated previously. Here we report an efficient ternary blend OSC with a PCE of 9.2%. We show that the third component can reduce surface trap densities in the ternary blend. Detailed studies unravel that the improved performance results from synergistic effects of enlarged open circuit voltage, suppressed trap-assisted recombination, enhanced light absorption, increased hole extraction, efficient energy transfer and better morphology. The working mechanism and high device performance demonstrate new insights and design guidelines for high-performance ternary blend solar cells and suggest that ternary structure is a promising platform to boost the efficiency of OSCs.

  1. Biodegradable polymer based ternary blends for removal of trace metals from simulated industrial wastewater.

    PubMed

    Prakash, N; Arungalai Vendan, S

    2016-02-01

    The ternary blends consisting of Chitosan (CS), Nylon 6 (Ny 6) and Montmorillonite clay (MM clay) were prepared by the solution blending method with glutaraldehyde. The prepared ternary blends were characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermo gravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bondings were established between chitosan, nylon 6 and montmorillonite clay. TGA showed the thermal stability of the blend is enhanced by glutaraldehyde as Crosslink agent. Results of XRD indicated that the relative crystalline of the pure chitosan film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend was rough and heterogenous. Further, it confirms the interaction between the functional groups of the blend components. The extent of removal of the trace metals was found to be almost the same. The removal of these metals at different pH was also done and the maximum removal of the metals was observed at pH 4.5 for both trace metals. Adsorption studies and kinetic analysis have also been made. Moreover, the protonation of amine groups is induced an electrostatic repulsion of cations. When the pH of the solution was more than 5.5, the sorption rate began to decrease. Besides, the quantity of adsorbate on absorbent was fitted as a function in Langmuir and Freundlich isotherm. The sorption kinetics was tested for pseudo first order and pseudo second order reaction. The kinetic experimental data correlated with the second order kinetic model and rate constants of sorption for kinetic models were calculated and accordingly, the correlation coefficients were obtained.

  2. Identification of individual isotopes in a polymer blend using tip enhanced Raman spectroscopy

    SciTech Connect

    Agapov, Rebecca L.; Scherger, Jacob D.; Sokolov, Alexei P.; Foster, Mark D.

    2015-03-11

    We use tip enhanced Raman spectroscopy (TERS) blinking measurements to identify the individual isotopes of non-Raman resonant polystyrene in a miscible, binary blend. Thus it demonstrates the sensitivity and selectivity required for nanoscale chemical imaging and broadens the types of surface components potentially identifiable with TERS.

  3. Effect of Blend Composition on Binary Organic Solar Cells Using a Low Band Gap Polymer.

    PubMed

    Wright, Matthew; Lin, Rui; Tayebjee, Murad J Y; Yang, Xiaohan; Veettil, Binesh Puthen; Wen, Xiaoming; Uddin, Ashraf

    2015-03-01

    This report investigates the influence of the solution blend composition of binary bulk heterojunction organic solar cells composed of poly(2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H- cyclopenta[2,1-b:3,4-b'dithiophene-2,6-diy

  4. Effects of electron-beam irradation on some structural properties of granulated polymer blends

    NASA Astrophysics Data System (ADS)

    Żenkiewicz, Marian; Czupryńska, Joanna; Polański, Julian; Karasiewicz, Tomasz; Engelgard, Włodzimierz

    2008-02-01

    The aim of this article was to show the effects of the electron radiation dose and presence of a compatibiliser on the peak melting temperature ( Tpm) of the crystalline phase, crystallinity ( Xc), and melt flow rate (MFR) of granulated blends of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) as well as of blends of LDPE, HDPE, and PP. The purpose of applying the high-energy electron radiation with doses up to 300 kGy and of adding a compatibiliser was to enhance mechanical properties of the studied blends and, at the same time, to investigate the possibility of using this technique in the processes of recycling polymeric materials. As the compatibilisers, the styrene-ethylene/butylene-styrene elastomer grafted with maleic anhydride (SEBS- g-MA) and trimethylol propane trimethacrylate (TMPTA) were utilised; they were added at the amounts of 5, 10, and 15 wt% and 1, 2, and 3 wt%, respectively. The enhancement of mechanical properties was accompanied by the following effects, discussed in this article: (i) a decrease in the peak melting temperature upon the electron radiation for the crystalline phase of LDPE, HDPE, and PP that constituted the studied granulated blends and (ii) changes in MFR upon both the electron radiation and the addition of compatibilisers.

  5. Determination of photocarrier density under continuous photoirradiation using spectroscopic techniques as applied to polymer: Fullerene blend films

    SciTech Connect

    Kanemoto, Katsuichi Nakatani, Hitomi; Domoto, Shinya

    2014-10-28

    We propose a method to determine the density of photocarrier under continuous photoirradiation in conjugated polymers using spectroscopic signals obtained by photoinduced absorption (PIA) measurements. The bleaching signals in the PIA measurements of polymer films and the steady-state absorption signals of oxidized polymer solution are employed to determine the photocarrier density. The method is applied to photocarriers of poly (3-hexylthiophene) (P3HT) in a blended film consisting of P3HT and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The photocarrier density under continuous photoirradiation of 580 mW/cm{sup 2} is determined to be 3.5 × 10{sup 16 }cm{sup −3}. Using a trend of the carrier density increasing in proportion to the square root of photo-excitation intensity, we provide a general formula to estimate the photocarrier density under simulated 1 sun solar irradiation for the P3HT: PCBM film of an arbitrary thickness. We emphasize that the method proposed in this study enables an estimate of carrier density without measuring a current and can be applied to films with no electrodes as well as to devices.

  6. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends.

    PubMed

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A; El-Enazi, Fouza

    2012-07-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN.

  7. Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends

    PubMed Central

    El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A.; El-Enazi, Fouza

    2011-01-01

    The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN. PMID:24115902

  8. Fabrication and characterization of a foamed polylactic acid (PLA)/ thermoplastic polyurethane (TPU) shape memory polymer (SMP) blend for biomedical and clinical applications

    NASA Astrophysics Data System (ADS)

    Song, Janice J.; Srivastava, Ijya; Kowalski, Jennifer; Naguib, Hani E.

    2014-03-01

    Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over static materials and are being studied extensively for biomedical and clinical applications (such as tissue stents and scaffolds). A previous study has demonstrated that the bio-compatible polymer blend of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) (50/50 and 70/30) exhibit good shape memory properties. In this study, the mechanical and thermo-mechanical (shape memory) properties of TPU/PLA SMP blends were characterized; the compositions studied were 80/20, 65/35, and 50/50 TPU/PLA. In addition, porous TPU/PLA SMP blends were fabricated with a gas-foaming technique; and the morphology of the porous structure of these SMPs foams were characterized with scanning electron microscopy (SEM). The TPU/PLA bio-compatible SMP blend was fabricated with melt-blending and compression molding. The glass transition temperature (Tg) of the SMP blends was determined with a differential scanning calorimeter (DSC). The mechanical properties studied were the stress-strain behavior, tensile strength, and elastic modulus; and the thermomechanical (or shape memory) properties studied were the shape fixity rate (Rf), shape recovery rate (Rr), response time, and the effect of recovery temperature on Rr. The porous 80/20 PLA/TPU SMP blend was found to have the highest tensile strength, toughness and percentage extension, as well as the lowest density and uniform pore structure in the micron and submicron scale. The porous 80/20 TPU/PLA SMP blend may be further developed for specific biomedical and clinical applications where a combination of tensile strength, toughness, and low density are required.

  9. Alternative polymer separation technology by centrifugal force in a melted state.

    PubMed

    Dobrovszky, Károly; Ronkay, Ferenc

    2014-11-01

    In order to upgrade polymer waste during recycling, separation should take place at high purity. The present research was aimed to develop a novel, alternative separation opportunity, where the polymer fractions were separated by centrifugal force in melted state. The efficiency of the constructed separation equipment was verified by two immiscible plastics (polyethylene terephthalate, PET; low density polyethylene, LDPE), which have a high difference of density, and of which large quantities can also be found in the municipal solid waste. The results show that the developed equipment is suitable not only for separating dry blended mixtures of PET/LDPE into pure components again, but also for separating prefabricated polymer blends. By this process it becomes possible to recover pure polymer substances from multi-component products during the recycling process. The adequacy of results was verified by differential scanning calorimetry (DSC) measurement as well as optical microscopy and Raman spectroscopy.

  10. Polymer blend of PLA/PHBV based bionanocomposites reinforced with nanocrystalline cellulose for potential application as packaging material.

    PubMed

    Dasan, Y K; Bhat, A H; Ahmad, Faiz

    2017-02-10

    The current research discusses the development of poly (lactic acid) (PLA) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced nanocrystalline cellulose bionanocomposites. The nanocrystalline cellulose was derived from waste oil palm empty fruit bunch fiber by acid hydrolysis process. The resulting nanocrystalline cellulose suspension was then surface functionalized by TEMPO-mediated oxidation and solvent exchange process. Furthermore, the PLA/PHBV/nanocrystalline cellulose bionanocomposites were produced by solvent casting method. The effect of the addition of nanocrystalline cellulose on structural, morphology, mechanical and barrier properties of bionanocomposites was investigated. The results revealed that the developed bionanocomposites showed improved mechanical properties and decrease in oxygen permeability rate. Therefore, the developed bio-based composite incorporated with an optimal composition of nanocrystalline cellulose exhibits properties as compared to the polymer blend.

  11. Rheological studies of PMMA-PVC based polymer blend electrolytes with LiTFSI as doping salt.

    PubMed

    Liew, Chiam-Wen; Durairaj, R; Ramesh, S

    2014-01-01

    In this research, two systems are studied. In the first system, the ratio of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride) (PVC) is varied, whereas in the second system, the composition of PMMA-PVC polymer blends is varied with dopant salt, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) with a fixed ratio of 70 wt% of PMMA to 30 wt% of PVC. Oscillation tests such as amplitude sweep and frequency sweep are discussed in order to study the viscoelastic properties of samples. Elastic properties are much higher than viscous properties within the range in the amplitude sweep and oscillatory shear sweep studies. The crossover of G' and G'' is absent. Linear viscoelastic (LVE) range was further determined in order to perform the frequency sweep. However, the absence of viscous behavior in the frequency sweep indicates the solid-like characteristic within the frequency regime. The viscosity of all samples is found to decrease as shear rate increases.

  12. Rheological Studies of PMMA–PVC Based Polymer Blend Electrolytes with LiTFSI as Doping Salt

    PubMed Central

    Liew, Chiam–Wen; Durairaj, R.; Ramesh, S.

    2014-01-01

    In this research, two systems are studied. In the first system, the ratio of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride) (PVC) is varied, whereas in the second system, the composition of PMMA–PVC polymer blends is varied with dopant salt, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) with a fixed ratio of 70 wt% of PMMA to 30 wt% of PVC. Oscillation tests such as amplitude sweep and frequency sweep are discussed in order to study the viscoelastic properties of samples. Elastic properties are much higher than viscous properties within the range in the amplitude sweep and oscillatory shear sweep studies. The crossover of and is absent. Linear viscoelastic (LVE) range was further determined in order to perform the frequency sweep. However, the absence of viscous behavior in the frequency sweep indicates the solid-like characteristic within the frequency regime. The viscosity of all samples is found to decrease as shear rate increases. PMID:25051241

  13. Uniform patchy and hollow rectangular platelet micelles from crystallizable polymer blends

    NASA Astrophysics Data System (ADS)

    Qiu, Huibin; Gao, Yang; Boott, Charlotte E.; Gould, Oliver E. C.; Harniman, Robert L.; Miles, Mervyn J.; Webb, Stephen E. D.; Winnik, Mitchell A.; Manners, Ian

    2016-05-01

    The preparation of colloidally stable, self-assembled materials with tailorable solid or hollow two-dimensional (2D) structures represents a major challenge. We describe the formation of uniform, monodisperse rectangular platelet micelles of controlled size by means of seeded-growth methods that involve the addition of blends of crystalline-coil block copolymers and the corresponding crystalline homopolymer to cylindrical micelle seeds. Sequential addition of different blends yields solid platelet block comicelles with concentric rectangular patches with distinct coronal chemistries. These complex nano-objects can be subject to spatially selective processing that allows their disassembly to form perforated platelets, such as well-defined hollow rectangular rings. The solid and hollow 2D micelles provide a tunable platform for further functionalization and potential for a variety of applications.

  14. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    NASA Astrophysics Data System (ADS)

    Jayaraman, R.; Vickraman, P.; Subramanian, N. M. V.; Justin, A. Simon

    2016-05-01

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) - filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10-5 Scm-1 was noted for 57.5 wt% -7.5 wt% plasticizer - filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10-5 S cm-1 and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 - 1000 cm-1 both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  15. Charge transfer dynamics in polymer-fullerene blends for efficient solar cells.

    PubMed

    Jarzab, Dorota; Cordella, Fabrizio; Lenes, Martijn; Kooistra, Floris B; Blom, Paul W M; Hummelen, Jan C; Loi, Maria A

    2009-12-31

    Blends of poly(3-hexylthiophene) (P3HT) and the bis-adduct of [6,6]-phenyl-C(61)-butyric acid methyl ester (bisPCBM) show enhanced performances in bulk-heterojunction solar cells compared to P3HT:PCBM thin films due to their higher open-circuit voltage. However, it is not clear whether the decrease of the short-circuit current observed in P3HT-bisPCBM blends originates from the 100 mV reduction of the offset between the lowest unoccupied molecular orbitals of the donor and the acceptor or from a change in the morphology. The analysis of the photoluminescence dynamics of the various bulk heterojunctions provides information on the dependence of the electron transfer process on their microstructure. We find that in solution, where the donor-acceptor distribution is homogeneous, the photoluminescence dynamics is the same for the bis- and PCBM-based blends, while in thin films the first shows a slower dynamics than the second. This result indicates that the reduction of the LUMO offset of approximately 100 meV does not influence the electron transfer efficiency but that the diversity between the photoluminescence dynamics in thin films should be ascribed to the different microstructure of the bulk heterojunctions fabricated with the two acceptors.

  16. Engineering nanostructured polymer blends with controlled nanoparticle location for excellent microwave absorption: a compartmentalized approach.

    PubMed

    Biswas, Sourav; Kar, Goutam Prasanna; Bose, Suryasarathi

    2015-07-14

    In order to obtain better materials, control over the precise location of nanoparticles is indispensable. It is shown here that ordered arrangements of nanoparticles, possessing different characteristics (electrical/magnetic dipoles), in the blend structure can result in excellent microwave absorption. This is manifested from a high reflection loss of ca. -67 dB for the best blend structure designed here. To attenuate electromagnetic radiation, the key parameters of high electrical conductivity and large dielectric/magnetic loss are targeted here by including a conductive material [multiwall carbon nanotubes, MWNTs], ferroelectric nanostructured material with associated relaxations in the GHz frequency [barium titanate, BT] and lossy ferromagnetic nanoparticles [nickel ferrite, NF]. In this study, bi-continuous structures were designed using 50/50 (by wt) blends of polycarbonate (PC) and polyvinylidene fluoride (PVDF). The MWNTs were modified using an electron acceptor molecule, a derivative of perylenediimide, which facilitates π-π stacking with the nanotubes and stimulates efficient charge transport in the blends. The nanoscopic materials have specific affinity towards the PVDF phase. Hence, by introducing surface-active groups, an ordered arrangement can be tailored. To accomplish this, both BT and NF were first hydroxylated followed by the introduction of amine-terminal groups on the surface. The latter facilitated nucleophilic substitution reactions with PC and resulted in their precise location. In this study, we have shown for the first time that by a compartmentalized approach, superior EM attenuation can be achieved. For instance, when the nanoparticles were localized exclusively in the PVDF phase or in both the phases, the minimum reflection losses were ca. -18 dB (for the MWNT/BT mixture) and -29 dB (for the MWNT/NF mixture), and the shielding occurred primarily through reflection. Interestingly, by adopting the compartmentalized approach wherein the

  17. The role of the deformational entropy in the miscibility of polymer blends investigated using a hybrid statistical mechanics and molecular dynamics model.

    PubMed

    Madkour, Tarek M; Salem, Sarah A; Miller, Stephen A

    2013-04-28

    To fully understand the thermodynamic nature of polymer blends and accurately predict their miscibility on a microscopic level, a hybrid model employing both statistical mechanics and molecular dynamics techniques was developed to effectively predict the total free energy of mixing. The statistical mechanics principles were used to derive an expression for the deformational entropy of the chains in the polymeric blends that could be evaluated from molecular dynamics trajectories. Evaluation of the entropy loss due to the deformation of the polymer chains in the case of coiling as a result of the repulsive interactions between the blend components or in the case of swelling due to the attractive interactions between the polymeric segments predicted a negative value for the deformational entropy resulting in a decrease in the overall entropy change upon mixing. Molecular dynamics methods were then used to evaluate the enthalpy of mixing, entropy of mixing, the loss in entropy due to the deformation of the polymeric chains upon mixing and the total free energy change for a series of polar and non-polar, poly(glycolic acid), PGA, polymer blends.

  18. Characterization of digital textile printing and polymer blend (PFO-DMP:P3HT) for application in manufacture of organic diodes emitting white light - WOLEDS

    NASA Astrophysics Data System (ADS)

    da Silva, Marco A. T.; Thomazini, Emanuelle F.; Albertini, Madson; Renzi, Wesley; Franchello, Flavio; Dias, Ivan F. L.; Duarte, José Leonil; Poças, Luiz C.; Lourenço, Sidney A.

    2016-12-01

    The research of materials and structures for the manufacture of organic diodes emitting white light WOLEDS has been very intense nowadays mainly due to the possibilities of its use in obtaining low-energy light consuming. The energy transfer between polymer materials has proven to be a great allied to search organic devices with emitting white light. Polymers such as PFO-DMP (donor) and P3HT (acceptor) are candidates for this application. In this work, P3HT, PFO-DMP and blends (PFO-DMP:P3HT (5%)) films were deposited by spin-coating on digital textile printing substrates. The optical properties of the digital textile printing, polymers and blend were studied by UV-VIS, steady-state photoluminescence (PL), PL quantum yield (PLQY) and Raman (all at 298 K) spectroscopy techniques. The digital textile printing were acquired from Isoliner, a Brazilian company specialized in this kind of textile. In the blend a strongly energy transfer from PFO-DMP to P3HT was observed. The PL spectrum of the PFO-DMP:P3HT (5%) covers the 430-730 nm range. From integrated PL spectra in the range of 13-643 K, it was obtained the temperature at which the phosphor loses 50% of its initial emission intensity, T1/2 = 430 K. Gaussian fits were performed, and the peaks were identified. Raman measurements were performed on substrates with and without polymers deposited and the results are in agreement with those found in the literature. Vibrational modes of textile increase the full width half maximum (FWHM), due to electron-phonons interaction. Results obtained through the coordinate calculation CIE from blend emission for various types of textile digital printing tested, showed the more appropriate combinations (substrate/blend) for emission in white.

  19. Optimized performance of quasi-solid-state DSSC with PEO-bismaleimide polymer blend electrolytes filled with a novel procedure.

    PubMed

    Lee, Dong Ha; Sun, Kyung Chul; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2014-12-01

    Dye-sensitized solar cell (DSSC) is an attractive renewable energy technology currently under intense investigation. Electrolyte plays an important role in the photovoltaic performance of the DSSCs and many efforts have been contributed to study different kinds of electrolytes with various characteristics such as liquid electrolytes, polymer electrolytes and so on. In this study, DSSC is developed by using quasi-solid electrolyte and a novel procedure is adopted for filling this electrolyte. The quasi-solid-state electrolyte was prepared by mixing Poly ethylene oxide (PEO) and bismaleimide together and constitution was taken as PEO (15 wt%) at various bismaleimide concentrations (1, 3, 5 wt%). The novel procedure of filling electrolyte consists of three major steps (first step: filling liquid electrolyte, second step: vaporization of liquid electrolyte, third step: refilling quasi-solid-state electrolyte). The electrochemical and photovoltaic performances of DSSCs with these electrolytes were also investigated. The electrochemical impedance spectroscopy (EIS) indicated that TiO2/Dye/electrolyte impedance is reduced and electron lifetime is increased, and consequently efficiency of cell has been improved after using this novel procedure. The photovoltaic power conversion efficiency of 6.39% has been achieved under AM 1.5 simulated sunlight (100 W/cm2) through this novel procedure and by using specified blend of polymers.

  20. Self reinforcing polymer composites

    SciTech Connect

    Kenig, S.

    1993-12-31

    In the advent of liquid crystalline polymers (LCPs), self reinforcing polymer composites comprising a polymer matrix and an LCP reinforcement, have become a reality. The so called self reinforcement is due to the LCPs orientability characteristics resulting from their rigid molecular backbone and anisotropy structure in the fluid state. Orientation development takes place during melt processing of the LCP composite blends where shear as well as elongational flows occur prior to consolidation to the solid state. By proper flow control anisotropy develops and in-situ composites are obtained. Polymer composites comprising self-reinforcement by LCPs during processing induced flow, were analyzed and studied with respect to their orientation development and resultant mechanical properties. The analysis commenced with the hydrodynamics of immiscible fluids in shear and elongational flows. Based on the analysis, orientation and morphology development in capillary extrusion was studied, using a variety of thermoplastic polymer matrices like amorphous and crystalline polyamides, polycarbonate and polyester in conjunction of a naphthalene based thermotropic LCP. Based on the flow-morphology relationship the amorphous polyamide/LCP composite was further investigated as it exhibited enhanced properties. Laminated composites based on LCP/amorphous polyamide were developed composed of unidirectional extruded and drawn sheets that were subsequently compression molded. Unidirectional, +45/{minus}45 and quasi-isotropic laminates were prepared and analyzed as to their microstructure and mechanical properties.

  1. Extruded films of blended chitosan, low density polyethylene and ethylene acrylic acid.

    PubMed

    Martínez-Camacho, A P; Cortez-Rocha, M O; Graciano-Verdugo, A Z; Rodríguez-Félix, F; Castillo-Ortega, M M; Burgos-Hernández, A; Ezquerra-Brauer, J M; Plascencia-Jatomea, M

    2013-01-16

    The obtaining of chitosan extruded films was possible by using low density polyethylene (LDPE) as a matrix polymer and ethylene-acrylic acid copolymer as an adhesive, in order to ensure adhesion in the interphase of the immiscible polymers. The obtained blend films were resistant; however, a reduction in the mechanical resistance was observed as chitosan concentration increased. The thermal stability of the films showed a certain grade of interaction between polymers as seen in FTIR spectra. The antifungal activity of the extruded films was assessed against Aspergillus niger and high inhibition percentages were observed, which may be mainly attributed to barrier properties of the extruded films and the limited oxygen availability, resulting in the inability of the fungi to grow. A low adherence of fungal spores to the material surface was observed, mainly in areas with chitosan clumps, which can serve as starting points for material degradation.

  2. Drug-polymer interaction and its significance on the physical stability of nifedipine amorphous dispersion in microparticles of an ammonio methacrylate copolymer and ethylcellulose binary blend.

    PubMed

    Huang, Jingjun; Wigent, Rodney J; Schwartz, Joseph B

    2008-01-01

    Using spectroscopic and thermal analysis, this study investigated drug-polymer interaction and its significance on the physical stability of drug amorphous dispersion in microparticles of an ammonio polymethacrylate copolymer (Eudragit RL) (RL) and ethylcellulose (EC) binary blend (RL/EC = 2:1 w/w) prepared for use in controlled release of poorly water-soluble drugs. Solid dispersion of the model drug, nifedipine in the microparticles could be described as an ideal amorphous mixture for drug loadings up to 11% w/w. The antiplasticizing effect of the polymer blend was indicated by a significant increase in the glass transition point from approximately 50 degrees C for the amorphous nifedipine to approximately 115 degrees C for its solid solution. Moreover, shifts in infrared vibration wavenumber of nifedipine carbonyl and amine groups suggested that the hydrogen bonds (H-bonds) originally formed among nifedipine molecules were broken and replaced by those formed between nifedipine and polymers in the microparticles. Further infrared analysis on nifedipine amorphous dispersions with a single polymer, namely RL or EC, confirmed the proposed hydrogen-bonding interactions; and their stability study results suggested that both antiplasticizing effects and hydrogen bonding of EC and RL with nifedipine might be responsible for the physical stability of the microparticles of nifedipine amorphous dispersion with a RL/EC binary blend.

  3. Bioinspired Non-iridescent Structural Color from Polymer Blend Thin Films

    NASA Astrophysics Data System (ADS)

    Nallapaneni, Asritha; Shawkey, Matthew; Karim, Alamgir

    Colors exhibited in biological species are either due to natural pigments, sub-micron structural variation or both. Structural colors thus exhibited can be iridescent (ID) or non-iridescent (NID) in nature. NID colors originate due to interference and coherent scattering of light with quasi-ordered micro- and nano- structures. Specifically, in Eastern Bluebird (Sialia sialis) these nanostructures develop as a result of phase separation of β-keratin from cytoplasm present in cells. We replicate these structures via spinodal blend phase separation of PS-PMMA thin films. Colors of films vary from ultraviolet to blue. Scattering of UV-visible light from selectively leeched phase separated blends are studied in terms of varying domain spacing (200nm to 2 μm) of film. We control these parameters by tuning annealing time and temperature. Angle-resolved spectroscopy studies suggest that the films are weakly iridescent and scattering from phase-separated films is more diffused when compared to well-mixed films. This study offers solutions to several color-based application in paints and coatings industry.

  4. On the Surface Free Energy of PVC/EVA Polymer Blends: Comparison of Different Calculation Methods.

    PubMed

    Michalski; Hardy; Saramago

    1998-12-01

    The surface free energy of polymeric films of polyvinylchloride (PVC) + poly(ethylene-co-vinylacetate) (EVA) blends was calculated using the van Oss treatment (Lifshitz and electron donor-electron acceptor components of surface free energy) and the Owens-Wendt treatment (dispersive and nondispersive components of surface free energy). Surface free energy results were found to be greatly dependent on the calculation method and on the number of standard liquids used for contact angle measurements. The nondispersive/donor-acceptor surface free energy component and the total surface free energy of polymeric films were always higher when the van Oss treatment was used compared to the Owens-Wendt treatment. Conversely, both methods led to similar apolar/Lifshitz components. All the calculation methods were in good agreement for the surface free energy of PVC; however, a discrepancy between the methods arose as EVA content in the blends increased. It seems that there is not yet a definite solution for the calculation of solid surface free energy. Further developments of existing models are needed in order to gain consistency when calculating this important physicochemical quantity. Copyright 1998 Academic Press.

  5. Conjugated-Polymer Blends for Organic Photovoltaics: Rational Control of Vertical Stratification for High Performance.

    PubMed

    Yan, Yu; Liu, Xuan; Wang, Tao

    2017-02-13

    The photoactive layer of bulk-heterojunction organic solar cells, in a thickness range of tens to hundreds of nanometers, comprises phase-separated electron donors and acceptors after solution casting. The component distribution in the cross-section of these thin films is found to be heterogeneous, with electron donors or acceptors accumulated or depleted near the electrode interfaces. This vertical stratification of the photovoltaic blend influences device metrics through its impact on charge transport and recombination, and consequently plays an important role in determining the power conversion efficiency of photovoltaic devices. Here, different techniques, e.g., surface analysis and sputter-assisted depth-profiling, reflectivity modeling, and 3D imaging, that have been employed to characterize vertical stratification in bulk-heterojunction photovoltaic blends are reviewed. The origins of vertical stratification are summarized, including thermodynamics, kinetics, surface free energy, and selective dissolubility. The impact of correct and wrong vertical stratification to device metrics of solar cells are highlighted. Examples are then given to demonstrate how desired vertical stratification can be controlled with properly aligned device architecture to enable solar cells with high efficiency.

  6. Reactive modification of polyesters and their blends

    NASA Astrophysics Data System (ADS)

    Wan, Chen

    2004-12-01

    the desired rheological and structural characteristics of the final products for potential applications such as low density extrusion foaming or compatibilization of immiscible polymer blends. Important modification conditions through coagents are identified and reaction mechanisms are proposed. A high MW saturated polyester, PET, can also be rheologically modified in extruders through low MW multifunctional anhydride and epoxy compounds by chain extension/branching. Several such modifiers were successfully screened in terms of their reactivity towards PET under controlled reactive extrusion conditions. A dianhydride with medium reactivity was then successfully used in a one-step reactive modification/extrusion foaming process to produce low density foams. A similar process was successfully used to produce small cell size foams from a four component system containing PET, PP and lesser amounts of a low molecular weight multifunctional epoxy compound and an acid functionalized polyolefin, the latter acting as compatibilizers.

  7. Multiphase blends from poly(L-lactide) and poly(methyl mathacrylate).

    PubMed

    Le, Kim-Phuong; Lehman, Richard; Remmert, Jessica; Vanness, Kenneth; Ward, Paula Marie L; Idol, James D

    2006-01-01

    Melt processing of poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was conducted over a targeted range of compositions with PLLAs of 118 and 316 kDa in molecular mass to identify morphologies and the phase relationships in these blends. These blends are of interest for use in biomaterials and the morphologies are critical for tissue-engineering studies where biodegradability, pore connectivity and surface texture control tissue viability and adhesion. Simple extrusion of the two polymers produced multiphase blends with an average domain size near 25 microm. Scanning electron microscopy and dynamic mechanical analysis demonstrated that these blends are immiscible, at least in a metastable sense, and regions of co-continuous structures were identified. Such co-continuous, which occurred generally in accordance with rheology prediction models, exhibit a fine interconnected structure that appears effective for fabricating certain biomaterials. A broad and unexpected transition appears in these blends, as measured by modulated differential scanning calorimetry between 70 and 100 degrees C, which may be the glass transition temperature of an alloy phase. The magnitude of this transition is greatest in the fine-structured co-continuous composition region of blends, suggesting the presence of a complex or other derivative of the two primary phases.

  8. Nanoscale probing of a polymer-blend thin film with tip-enhanced Raman spectroscopy.

    PubMed

    Yeo, Boon-Siang; Amstad, Esther; Schmid, Thomas; Stadler, Johannes; Zenobi, Renato

    2009-04-01

    Fundamental advances have been made in the spatially resolved chemical analysis of polymer thin films. Tip-enhanced Raman spectroscopy (TERS) is used to investigate the surface composition of a mixed polyisoprene (PI) and polystyrene (PS) thin film. High-quality TER spectra are collected from these nonresonant Raman-active polymers. A wealth of structural information is obtained, some of which cannot be acquired with conventional analytical techniques. PI and PS are identified at the surface and subsurface, respectively. Differences in the band intensities suggest strongly that the polymer layers are not uniformly thick, and that nanopores are present under the film surface. The continuous PS subsurface layer and subsurface nanopores have hitherto not been identified. These data are obtained with nanometer spatial resolution. Confocal far-field Raman spectroscopy and X-ray photoelectron spectroscopy are employed to corroborate some of the results. With routine production of highly enhancing TERS tips expected in the near future, it is predicted that TERS will be of great use for the rigorous chemical analysis of polymer and other composite systems with nanometer spatial resolution.

  9. Materials for the Plastic Retina: Network Blends for Arrays of Polymer Grid Triodes

    DTIC Science & Technology

    1999-01-19

    sheet resistance uniformity and long-term stability. Additionally, we have synthesized several varieties of conducting polymer systems, including new PANI derivatives and Mends. The ultimate goal of this effort was...UNIAX under a joint BMDO/DARPA program). For the Plastic Retina, or the Thin Film Analog Image Processor (TAIP), a sheet resistance greater than

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

    NASA Astrophysics Data System (ADS)

    Sreeram, Arvind

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

  11. The fate of electron-hole pairs in polymer:fullerene blends for organic photovoltaics.

    PubMed

    Causa', Martina; De Jonghe-Risse, Jelissa; Scarongella, Mariateresa; Brauer, Jan C; Buchaca-Domingo, Ester; Moser, Jacques-E; Stingelin, Natalie; Banerji, Natalie

    2016-09-02

    There has been long-standing debate on how free charges are generated in donor:acceptor blends that are used in organic solar cells, and which are generally comprised of a complex phase morphology, where intermixed and neat phases of the donor and acceptor material co-exist. Here we resolve this question, basing our conclusions on Stark effect spectroscopy data obtained in the absence and presence of externally applied electric fields. Reconciling opposing views found in literature, we unambiguously demonstrate that the fate of photogenerated electron-hole pairs-whether they will dissociate to free charges or geminately recombine-is determined at ultrafast times, despite the fact that their actual spatial separation can be much slower. Our insights are important to further develop rational approaches towards material design and processing of organic solar cells, assisting to realize their purported promise as lead-free, third-generation energy technology that can reach efficiencies over 10%.

  12. The fate of electron–hole pairs in polymer:fullerene blends for organic photovoltaics

    PubMed Central

    Causa', Martina; De Jonghe-Risse, Jelissa; Scarongella, Mariateresa; Brauer, Jan C.; Buchaca-Domingo, Ester; Moser, Jacques-E.; Stingelin, Natalie; Banerji, Natalie

    2016-01-01

    There has been long-standing debate on how free charges are generated in donor:acceptor blends that are used in organic solar cells, and which are generally comprised of a complex phase morphology, where intermixed and neat phases of the donor and acceptor material co-exist. Here we resolve this question, basing our conclusions on Stark effect spectroscopy data obtained in the absence and presence of externally applied electric fields. Reconciling opposing views found in literature, we unambiguously demonstrate that the fate of photogenerated electron–hole pairs—whether they will dissociate to free charges or geminately recombine—is determined at ultrafast times, despite the fact that their actual spatial separation can be much slower. Our insights are important to further develop rational approaches towards material design and processing of organic solar cells, assisting to realize their purported promise as lead-free, third-generation energy technology that can reach efficiencies over 10%. PMID:27586309

  13. The fate of electron-hole pairs in polymer:fullerene blends for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Causa', Martina; de Jonghe-Risse, Jelissa; Scarongella, Mariateresa; Brauer, Jan C.; Buchaca-Domingo, Ester; Moser, Jacques-E.; Stingelin, Natalie; Banerji, Natalie

    2016-09-01

    There has been long-standing debate on how free charges are generated in donor:acceptor blends that are used in organic solar cells, and which are generally comprised of a complex phase morphology, where intermixed and neat phases of the donor and acceptor material co-exist. Here we resolve this question, basing our conclusions on Stark effect spectroscopy data obtained in the absence and presence of externally applied electric fields. Reconciling opposing views found in literature, we unambiguously demonstrate that the fate of photogenerated electron-hole pairs--whether they will dissociate to free charges or geminately recombine--is determined at ultrafast times, despite the fact that their actual spatial separation can be much slower. Our insights are important to further develop rational approaches towards material design and processing of organic solar cells, assisting to realize their purported promise as lead-free, third-generation energy technology that can reach efficiencies over 10%.

  14. Development of new generation of copolymers via reactive extrusion in a twin screw extruder and application in various PVC blends

    NASA Astrophysics Data System (ADS)

    Kim, In

    Polymerization in twin screw extruders has largely involved homopolymers. Here we generalize this and polymerize a range of copolymers and terpolymers including epsilon-caprolactam(CA), o-lauryl lactam(LA), epsilon-caprolactone(CL), and gamma-butyrolactone(GBL) in a modular intermeshing co-rotating twin screw extruder. We considered different types of copolymer structures (di-block, tri-block, and random-block) and different backbones of copolymer(lactams-lactones) as well as the variables of temperature profile, screw speed, monomer feed rate, the ratio of monomer to initiator, and feeding order of co-monomers on reactive extrusion of polyamides-polylactones based (co)polymers. Specially designed block copolymers have played a role as compatibilizing agents in the system of immiscible polymer blends. We apply the di-block copolymer(P(LA-b-CL)) and random block copolymer (P(LA/CA-b-CL)) produced by reactive extrusion as a compatibilizing agent in immiscible polymer blend systems: (i) poly(vinyl chloride) (PVC)/polyamide 12 (PA12), (ii) PVC/polypropylene(PP), and (iii) PVC/Ethylene-propylene-non-conjugated diene elastomer(EPDM).

  15. Three-Way-Switchable (Right/Left/OFF) Selective Reflection of Circularly Polarized Light on Solid Thin Films of Helical Polymer Blends.

    PubMed

    Nagata, Yuuya; Uno, Makoto; Suginome, Michinori

    2016-06-13

    Two poly(quinoxaline-2,3-diyl) copolymers bearing miscibility-enhancing 8-chlorooctyloxy and (S)-2-methylbutoxy or n-butoxy side chains were synthesized. After annealing in CHCl3 vapor, a polymer-blend film of these copolymers exhibited selective reflection of right-handed circularly polarized light (CPL) in the visible region. The handedness of the CPL reflected was completely inverted upon annealing of the film in THF vapor. Annealing in n-hexane vapor resulted in the phase separation of the polymer blend, which turned the selective reflection off. This three-way-switchable reflection, that is, reflection of right-handed or left-handed CPL, together with an OFF state, could be observed visually through right- and left-handed CPL filters.

  16. Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends

    PubMed Central

    Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

    2009-01-01

    Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries. PMID:20354587

  17. Novel Salted Anionic-Cationic Polymethacrylate Polymer Blends for Sustained Release of Acidic And Basic Drugs.

    PubMed

    Obeidat, Wasfy M; Qasim, Duaa; Nokhodchi, Ali; Al-Jabery, Ahmad; Sallam, Al-Sayed

    2016-05-02

    Since a unique matrix tablet formulation that independently controls the release of various drug types is in a great demand, the objective of this research was to develop a sustained release matrix tablet as a universal dosage form using a binary mixture of the salt forms of Eudragit polymers rather than their interpolyelectrolyte complexes. Tablets were prepared by wet granulation and compressed at different compression forces, depending on drug type. Dissolution tests were conducted using USP XXII rotating paddle apparatus at 50 rpm at 37°C in consecutive pH stages. Tablets containing Ibuprofen (IB) as a model acidic drug and Metronidazole (MD) as a model basic drug showed controlled/sustained release behavior. For IB tablets containing 80% Ibuprofen and 5% (w/w) polymeric combination; the time for 50% of the drug release was about 24 hours compared to 8.5 hours for plain tablets containing 80% IB. In case of MD, the drug release extended to about 7 hours for tablets containing 80% MD and 5% (w/w) polymeric combination, compared to about 1 hour for plain tablets containing 80% MD. In terms of extending the release of medications, the dissolution profiles of the tablets containing polymeric salts forms were found to be statistically superior to tablets prepared by direct compression of the polymers in their powdered base forms, and superior to tablets containing the same polymers granulated using isopropyl alcohol. The findings indicated the significance of combining the polymers in their salt forms in controlling the release of various drug types from matrices.

  18. PHEA-PLLA: A New Polymer Blend For Tissue Engineering Applications

    NASA Astrophysics Data System (ADS)

    Pavia, Francesco Carfi; La Carrubba, Vincenzo; Palumbo, Fabio; Giammona, Gaetano; Brucato, Valerio

    2011-05-01

    One of most important features that a material should have in order to be utilized for tissue engineering applications is its biocompatibility and its chemical surface. These properties are required for a high degree of cell adhesion on the scaffold. Poly-L-lactid acid (PLLA) is a biocompatible synthetic polymer approved by the Food and Drug Administration for human clinical applications. It has been largely employed, in the last years, as a constituent of surgical and implantable devices. PHEA is a biocompatible water-soluble synthetic polymer, with a protein-like structure, whose use as a drug carrier and as starting material for many other biomedical and pharmaceutical applications has been reported in the literature. In this work a copolymer (PHEA-PLLA) of the aforementioned polymers was synthesized and characterized the possibility to produce porous scaffolds with it was assessed. The results have shown that is possible to prepare scaffolds of PHEA-PLLA via Thermally Induced Phase Separation (TIPS). The scaffolds as-obtained present on theirs bulk an open porous structure with interconnected pores whose average pore size was ˜ 20 μm. Moreover a cloud point curve for the system PHEA-PLLA/Dioxane/water was built in order to find the more appropriate temperatures for the TIPS process.

  19. Solid phase graft copolymerization of acrylic monomers onto thermoplastics and their use as blend compatibilizers

    NASA Astrophysics Data System (ADS)

    Subramanian, Srinivas

    This research work is an extension of some of the earlier work done on the development of solid phase grafting technique to graft various monomers onto polymers as well as postulation of the usefulness of the graft copolymers thus synthesized. Polystyrene grafted with acrylic acid, previously developed in bench scale, was synthesized in pilot-plant scale batches. Process parameter studies on the grafting of acrylic acid onto polypropylene and developmental studies on the grafting of maleic anhydride onto polystyrene were also done. Polymers grafted with polar molecules such as maleic anhydride and acrylic acid have been used to compatibilize immiscible blends of polar and non-polar polymers. On the same note, the applicability of the solid phase graft copolymers as blend compatibilizers were investigated and their performance was compared to commercially available compatibilizers. Solid phase graft copolymerization process is a technique to synthesize graft copolymers. Some of its salient features are use of minimal solvent to conduct the reaction and easy equipment modification. It is a low pressure and low temperature process. This technique provides a viable alternative to the environmentally hazardous, and time consuming conventional process currently in use. Hence, development of this technique could be beneficial not only to the plastics industry, but also to mankind. Also, this technique provides a low-cost and extremely easy method to develop graft copolymers such as acrylic acid functionalized polymers that are rapidly gaining popularity as blend compatibilizers and polymer reinforcing agents. A study that proves the potential of these solid phase graft copolymers as good blend compatibilizers for industrially important immiscible polymers will develop interest in the industries about this grafting process. The free radical solid phase graft copolymerization process was carried in a modified Brabender-type mixer fitted with specially designed blades to

  20. An interfacial instability in a transient wetting layer leads to lateral phase separation in thin spin-cast polymer-blend films.

    PubMed

    Heriot, Sasha Y; Jones, Richard A L

    2005-10-01

    Spin-coating is a very widely used technique for making uniform thin polymer films. For example, the active layers in most experimental semiconducting polymer-based devices, such as light-emitting diodes and photovoltaics, are made this way. The efficiency of such devices can be improved by using blends of polymers; these phase separate during the spin-coating process, creating the complex morphology that leads to performance improvements. We have used time-resolved small-angle light scattering and light reflectivity during the spin-coating process to study the development of structure directly. Our results provide evidence that a blend of two polymers first undergoes vertical stratification; the interface between the stratified layers then becomes unstable, leading to the final phase-separated thin film. This has given us the basis for establishing a full mechanistic understanding of the development of morphology in thin mixed polymer films, allowing a route to the rational design of processing conditions so as to achieve desirable morphologies by self-assembly.

  1. Coupled growth in immiscible alloys

    NASA Astrophysics Data System (ADS)

    Andrews, J. Barry; Hayes, Larry C.; Arikawa, Y.; O'Dell, S.; Cheney, A.

    1996-07-01

    This paper discusses the flight experiment 'Coupled Growth in Hypermonotectics' schedules to fly aboard the life and microgravity spacelab mission during the summer of 1996. The experiment is designed to directionally solidify samples in immiscible alloy systems in an attempt to obtain an improved understanding of the physics controlling the solidification process. This paper specifically addresses some of the unique difficulties concerning ampoule design for these experiments. As an example, an ampoule material must be utilized that is not wet by the minor immiscible liquid phase. In addition, a means must be provided to accommodate thermal contraction and solidification shrinkage during processing in order to avoid free surface formation on the melt. An attempt has also been made to control thermal end effects in order to obtain a relatively constant growth rate during processing. The final design results in an ampoule assembly that contains insulating segments, dummy samples, moving pistons and a high temperature spring assembly. The details of this design and the results of ground based testing will be discussed.

  2. FTIR studies of plasticized poly(vinyl alcohol)-chitosan blend doped with NH 4NO 3 polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Kadir, M. F. Z.; Aspanut, Z.; Majid, S. R.; Arof, A. K.

    2011-03-01

    Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH 4NO 3) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm -1 and the amine band at 1591 cm -1 to 1650 and 1557 cm -1 respectively and the shift of the hydroxyl band from 3377 to 3354 cm -1. The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm -1 and is observed at 3343 cm -1 in the spectrum of the PVA film. On addition of NH 4NO 3 up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm -1 to 1642, 1541 and 3348 cm -1 indicating that the chitosan has complexed with the salt. In the PVA-NH 4NO 3 spectrum, the hydroxyl band has shifted from 3343 to 3272 cm -1 on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH 4NO 3 systems. In the spectrum of PVA-chitosan-NH 4NO 3-EC complex, the doublet C dbnd O stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC.

  3. FTIR studies of plasticized poly(vinyl alcohol)-chitosan blend doped with NH4NO3 polymer electrolyte membrane.

    PubMed

    Kadir, M F Z; Aspanut, Z; Majid, S R; Arof, A K

    2011-03-01

    Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH(4)NO(3)) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm(-1) and the amine band at 1591 cm(-1) to 1650 and 1557 cm(-1) respectively and the shift of the hydroxyl band from 3377 to 3354 cm(-1). The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm(-1) and is observed at 3343 cm(-1) in the spectrum of the PVA film. On addition of NH(4)NO(3) up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm(-1) to 1642, 1541 and 3348 cm(-1) indicating that the chitosan has complexed with the salt. In the PVA-NH(4)NO(3) spectrum, the hydroxyl band has shifted from 3343 to 3272 cm(-1) on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH(4)NO(3) systems. In the spectrum of PVA-chitosan-NH(4)NO(3)-EC complex, the doublet CO stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC.

  4. Nitrogen-Containing Carbon Nanotube Synthesized from Polymelem and Activated Carbon Derived from Polymer Blend

    NASA Astrophysics Data System (ADS)

    Qin, Nan

    Polymelem possesses a polymeric structure of heptazine (C6N 7) rings connected by amine bridges and our study has demonstrated that it is a promising precursor for the synthesis of nitrogen-containing carbon materials. Nitrogen-containing carbon nanotube (NCNT) was produced by pyrolyzing polymelem as a dual source of carbon and nitrogen with Raney nickel in a high pressure stainless steel cell. Activated carbon was produced from poly(ether ether ketone)/poly(ether imide) (PEEK/PEI blend) and incorporated with polymelem to enhance the hydrogen adsorption. Polymelem was successfully synthesized by pyrolyzing melamine at 450--650 °C and its structure was elucidated by 13C solid state NMR, FTIR, and XRD. The molecular weight determined by a novel LDI MS equipped with a LIFT mode illuminated that polymelem has both linear and cyclic connectivity with a degree of polymerization of 2--5 depending on the synthesis temperature. The decomposition products of polymelem were determined to be cyanoamide, dicyanoamide, and tricyanoamine. Tricyanoamine is the smallest carbon nitride molecule and has been experimentally confirmed for the first time in this study. When polymelem was decomposed in the presence of Raney nickel, homogenous NCNT with nitrogen content of ˜ 4--19 atom% was produced. A mechanism based on a detail analysis of the TEM images at different growth stages proposed that the NCNT propagated via a tip-growth mechanism originating at the nano-domains within the Raney nickel, and was accompanied with the aggregation of the nickel catalysts. Such NCNT exhibited a cup-stack wall structure paired with a compartmental feature. The nitrogen content, tube diameter and wall thickness greatly depended on synthesis conditions. The activated carbon derived from PEEK/PEI blend demonstrated a surface area up to ˜3000 m2/g, and average pore size of < 20 A. Such activated carbon exhibited a hydrogen storage capacity of up to 6.47 wt% at 40 bar, 77 K. The activated carbon has

  5. Hydrodynamic-flow-driven phase evolution in a polymer blend film modified by diblock copolymers

    NASA Astrophysics Data System (ADS)

    Rysz, J.; Ermer, H.; Budkowski, A.; Bernasik, A.; Lekki, J.; Juengst, G.; Brenn, R.; Kowalski, K.; Camra, J.; Lekka, M.; Jedliński, J.

    We have studied surface-directed phase separation in thin films of deuterated polystyrene and poly(bromostyrene) (with 22.7% of monomers brominated) using ^{{3}}He nuclear reaction analysis, dynamic secondary ion mass spectroscopy and atomic force microscopy combined with preferential dissolution. The crossover from competing to neutral surfaces of the critical blend film (cast onto Au) was commenced: polyisoprene-polystyrene diblock copolymers were added and segregated to both surfaces reducing in a tuneable manner the effective interactions. Two main stages of phase evolution are characterised by i) the growth of two surface layers and by ii) the transition from the four-layer to the final bilayer morphology. For increasing copolymer content the kinetics of the first stage is hardly affected but the amplitude of composition oscillations is reduced indicating more fragmented inner layers. As a result, a faster mass flow to the surfaces and an earlier completion of the second stage were observed. The hydrodynamic flow mechanism, driving both stages, is evidenced by nearly linear growth of the surface layer and by mass flow channels extending from the surface layer into the bulk. The final bilayer structure, formed even for the surfaces covered by strongly overlapped copolymers, is indicative of long-range (antisymmetric) surface forces.

  6. Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend

    NASA Astrophysics Data System (ADS)

    Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

    2016-10-01

    Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d2‧,3‧-d‧]benzo[1,2-b4,5-b‧]dithiophene (DTBDT-C6) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm2 V‑1 s‑1 at low operation voltage of ‑5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

  7. Bulk heterojunction morphology of polymer:fullerene blends revealed by ultrafast spectroscopy

    NASA Astrophysics Data System (ADS)

    Serbenta, Almis; Kozlov, Oleg V.; Portale, Giuseppe; van Loosdrecht, Paul H. M.; Pshenichnikov, Maxim S.

    2016-11-01

    Morphology of organic photovoltaic bulk heterojunctions (BHJs) – a nanoscale texture of the donor and acceptor phases – is one of the key factors influencing efficiency of organic solar cells. Detailed knowledge of the morphology is hampered by the fact that it is notoriously difficult to investigate by microscopic methods. Here we all-optically track the exciton harvesting dynamics in the fullerene acceptor phase from which subdivision of the fullerene domain sizes into the mixed phase (2–15 nm) and large (>50 nm) domains is readily obtained via the Monte-Carlo simulations. These results were independently confirmed by a combination of X-ray scattering, electron and atomic-force microscopies, and time-resolved photoluminescence spectroscopy. In the large domains, the excitons are lost due to the high energy disorder while in the ordered materials the excitons are harvested with high efficiency even from the domains as large as 100 nm due to the absence of low-energy traps. Therefore, optimizing of blend nanomorphology together with increasing the material order are deemed as winning strategies in the exciton harvesting optimization.

  8. Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend

    PubMed Central

    Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

    2016-01-01

    Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d;2′,3′-d′]benzo[1,2-b;4,5-b′]dithiophene (DTBDT-C6) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm2 V−1 s−1 at low operation voltage of −5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas. PMID:27698493

  9. Printed 2 V-operating organic inverter arrays employing a small-molecule/polymer blend.

    PubMed

    Shiwaku, Rei; Takeda, Yasunori; Fukuda, Takashi; Fukuda, Kenjiro; Matsui, Hiroyuki; Kumaki, Daisuke; Tokito, Shizuo

    2016-10-04

    Printed organic thin-film transistors (OTFTs) are well suited for low-cost electronic applications, such as radio frequency identification (RFID) tags and sensors. Achieving both high carrier mobility and uniform electrical characteristics in printed OTFT devices is essential in these applications. Here, we report on printed high-performance OTFTs and circuits using silver nanoparticle inks for the source/drain electrodes and a blend of dithieno[2,3-d;2',3'-d']benzo[1,2-b;4,5-b']dithiophene (DTBDT-C6) and polystyrene for the organic semiconducting layer. A high saturation region mobility of 1.0 cm(2) V(-1) s(-1) at low operation voltage of -5 V was obtained for relatively short channel lengths of 9 μm. All fifteen of the printed pseudo-CMOS inverter circuits were formed on a common substrate and operated at low operation voltage of 2 V with the total variation in threshold voltage of 0.35 V. Consequently, the printed OTFT devices can be used in more complex integrated circuit applications requiring low manufacturing cost over large areas.

  10. Bulk heterojunction morphology of polymer:fullerene blends revealed by ultrafast spectroscopy

    PubMed Central

    Serbenta, Almis; Kozlov, Oleg V.; Portale, Giuseppe; van Loosdrecht, Paul H. M.; Pshenichnikov, Maxim S.

    2016-01-01

    Morphology of organic photovoltaic bulk heterojunctions (BHJs) – a nanoscale texture of the donor and acceptor phases – is one of the key factors influencing efficiency of organic solar cells. Detailed knowledge of the morphology is hampered by the fact that it is notoriously difficult to investigate by microscopic methods. Here we all-optically track the exciton harvesting dynamics in the fullerene acceptor phase from which subdivision of the fullerene domain sizes into the mixed phase (2–15 nm) and large (>50 nm) domains is readily obtained via the Monte-Carlo simulations. These results were independently confirmed by a combination of X-ray scattering, electron and atomic-force microscopies, and time-resolved photoluminescence spectroscopy. In the large domains, the excitons are lost due to the high energy disorder while in the ordered materials the excitons are harvested with high efficiency even from the domains as large as 100 nm due to the absence of low-energy traps. Therefore, optimizing of blend nanomorphology together with increasing the material order are deemed as winning strategies in the exciton harvesting optimization. PMID:27824085

  11. Effects of TiO2 addition on ionic conductivity of PVC/PEMA blend based composite polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Subban, R. H. Y.; Sukri, Nursyazwani

    2015-08-01

    PVC/PEMA blend based polymer electrolytes with lithium bistrifluoromethane sulfonimide (LiN(CF3SO2)2) and PVC/PEMA/(LiN(CF3SO2)2-TiO2 films were prepared by solution cast technique. The sample containing 35 wt. % LiN(CF3SO2)2 exhibited the highest conductivity of 1.75 × 10-5 Scm-1. The conductivity of the sample increased to 2.12 × 10-5 Scm-1 and 4.61 × 10-5 Scm-1 when 4 wt. % and 10 wt. % of titanium dioxide (TiO2) was added to the sample at 65 wt. % PVC/PEMA-35 wt. % LiN(CF3SO2)2 composition respectively. The low increase in conductivity is attributed to two competing factors: increase in crystallinity as accounted by X-Ray diffraction (XRD) and decrease in glass transition temperature as accounted by differential scanning calorimetry (DSC).

  12. Effects of TiO{sub 2} addition on ionic conductivity of PVC/PEMA blend based composite polymer electrolyte

    SciTech Connect

    Subban, R. H. Y.; Sukri, Nursyazwani

    2015-08-28

    PVC/PEMA blend based polymer electrolytes with lithium bistrifluoromethane sulfonimide (LiN(CF{sub 3}SO{sub 2}){sub 2}) and PVC/PEMA/(LiN(CF{sub 3}SO{sub 2}){sub 2}-TiO{sub 2} films were prepared by solution cast technique. The sample containing 35 wt. % LiN(CF{sub 3}SO{sub 2}){sub 2} exhibited the highest conductivity of 1.75 × 10{sup −5} Scm{sup −1}. The conductivity of the sample increased to 2.12 × 10{sup −5} Scm{sup −1} and 4.61 × 10{sup −5} Scm{sup −1} when 4 wt. % and 10 wt. % of titanium dioxide (TiO{sub 2}) was added to the sample at 65 wt. % PVC/PEMA-35 wt. % LiN(CF{sub 3}SO{sub 2}){sub 2} composition respectively. The low increase in conductivity is attributed to two competing factors: increase in crystallinity as accounted by X-Ray diffraction (XRD) and decrease in glass transition temperature as accounted by differential scanning calorimetry (DSC)

  13. Rechargeable solid polymer electrolyte battery cell

    DOEpatents

    Skotheim, Terji

    1985-01-01

    A rechargeable battery cell comprising first and second electrodes sandwiching a solid polymer electrolyte comprising a layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte adjacent said polymer blend and a layer of dry solid polymer electrolyte adjacent said layer of polymer blend and said second electrode.

  14. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis; Rasmidi, Rosfayanti; Subban, Ri Hanum Yahaya; Yahya, Muhd Zu Azhan

    2015-08-01

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d6) solution of the purified polymer using 1H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10-3 Scm-1 at 30°C and 3.383 × 10-3 Scm-1 at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  15. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    SciTech Connect

    Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis; Rasmidi, Rosfayanti; Subban, Ri Hanum Yahaya; Yahya, Muhd Zu Azhan

    2015-08-28

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  16. Long-lived charge carrier dynamics in polymer/quantum dot blends and organometal halide perovskites

    NASA Astrophysics Data System (ADS)

    Nagaoka, Hirokazu

    Solution-processable semiconductors offer a potential route to deploy solar panels on a wide scale, based on the possibility of reduced manufacturing costs by using earth-abundant materials and inexpensive production technologies, such as inkjet or roll-to-roll printing. Understanding the fundamental physics underlying device operation is important to realize this goal. This dissertation describes studies of two kinds of solar cells: hybrid polymer/PbS quantum dot solar cells and organometal halide perovskite solar cells. Chapter two discusses details of the experimental techniques. Chapter three and four explore the mechanisms of charge transfer and energy transfer spectroscopically, and find that both processes contribute to the device photocurrent. Chapter four investigates the important question of how the energy level alignment of quantum dot acceptors affects the operation of hybrid polymer/quantum dot solar cells, by making use of the size-tunable energy levels of PbS quantum dots. We observe that long-lived charge transfer yield is diminished at larger dot sizes as the energy level offset at the polymer/quantum dot interface is changed through decreasing quantum confinement using a combination of spectroscopy and device studies. Chapter five discusses the effects of TiO2 surface chemistry on the performance of organometal halide perovskite solar cells. Specifically, chapter five studies the effect of replacing the conventional TiO2 electrode with Zr-doped TiO2 (Zr-TiO2). We aim to explore the correlation between charge carrier dynamics and device studies by incorporating zirconium into TiO2. We find that, compared to Zr-free controls, solar cells employing Zr-TiO2 give rise to an increase in overall power conversion efficiency, and a decrease in hysteresis. We also observe longer carrier lifetimes and higher charge carrier densities in devices on Zr-TiO2 electrodes at microsecond times in transient photovoltage experiments, as well as at longer persistent

  17. Pins composed of poly(L-lactic acid)/poly(3- hydroxybutyrate-co-hydroxyvalerate) PLLA/PHBV blends: Degradation in vitro.

    PubMed

    Ferreira, B M P; Duek, E A R

    2005-01-01

    Bioabsorbable polymers have shown good clinical success in the fixation and stabilization of bone fractures. Understanding and controlling polymer prosthetic degradation and the effect of the degradation products in vivo are crucial for successful implant developments. In this study, pins made from blends of PLLA/PHBV of varying compositions were degraded in phosphate buffer and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The PLLA/PHBV blends were found to be immiscible. PLLA began to degrade after approximately 12 weeks, whereas PHBV showed some degradation only after 53 weeks. The crystallinity of the blends increased with degradation. In conclusion, PHBV improved the thermal properties of PLLA and reduced the brittleness of the blends tested. The 40/60 PLLA/PHBV blend had the best properties for use in orthopedics since it degraded quicker than pure PHBV, and yet maintained its crystallinity for longer than PLLA; in addition, this blend did not have the brittleness of PLLA. (Journal of Applied Biomaterials and Biomechanics 2005; 3: 50-60).

  18. Flow regimes during immiscible displacement

    DOE PAGES

    Armstrong, Ryan T.; Mcclure, James; Berrill, Mark A.; ...

    2017-02-01

    Fractional ow of immiscible phases occurs at the pore scale where grain surfaces and phases interfaces obstruct phase mobility. However, the larger scale behavior is described by a saturation-dependent phenomenological relationship called relative permeability. As a consequence, pore-scale parameters, such as phase topology and/ or geometry, and details of the flow regime cannot be directly related to Darcy-scale flow parameters. It is well understood that relative permeability is not a unique relationship of wetting-phase saturation and rather depends on the experimental conditions at which it is measured. Herein we use fast X-ray microcomputed tomography to image pore-scale phase arrangements duringmore » fractional flow and then forward simulate the flow regimes using the lattice-Boltzmann method to better understand the underlying pore-scale flow regimes and their influence on Darcy-scale parameters. We find that relative permeability is highly dependent on capillary number and that the Corey model fits the observed trends. At the pore scale, while phase topologies are continuously changing on the scale of individual pores, the Euler characteristic of the nonwetting phase (NWP) averaged over a sufficiently large field of view can describe the bulk topological characteristics; the Euler characteristic decreases with increasing capillary number resulting in an increase in relative permeability. Lastly, we quantify the fraction of NWP that flows through disconnected ganglion dynamics and demonstrate that this can be a significant fraction of the NWP flux for intermediate wetting-phase saturation. Furthermore, rate dependencies occur in our homogenous sample (without capillary end effect) and the underlying cause is attributed to ganglion flow that can significantly influence phase topology during the fractional flow of immiscible phases.« less

  19. Characterization and development of new hydrogenated acrylonitrile-butadiene rubber blends

    NASA Astrophysics Data System (ADS)

    Severe, Geralda

    Characteristics were determined for hydrogenated acrylonitrile-butadiene rubber (HNBR), which is a copolymer of butadiene and acrylonitrile made from hydrogenation of the diene segment in acrylonitrile rubber. There was close attention given to the glass transition behavior of HNBR and its tendency to crystallize in the quiescent and in stretching state. The glass transition behavior in HNBR was similar to that of other ethylene copolymers such as for example ethylene vinyl-acetate etc. The crystallinity in HNBR at high acrylonitrile content was due to alternating sequence of acrylonitrile and hydrogenated trans-1,4 butadiene rubber. Furthermore, the structure of HNBR does not have any effect on it rheological properties at the temperature investigated. HNBR exhibits a zero shear viscosity. It is common knowledge that most polymers are immiscible. However, over the years scientists have found numerous miscible polymers. On that basis we investigated miscibility between HNBR with ethylenic copolymers, chlorinated polymers, diene polymers, and hydrogenated acrylonitrile-butadiene rubber. HNBR is miscible with high chlorine content chlorinated polymers like chlorinated polyethylene (42% Cl), chlorosulfonated polyethylene (43% Cl), PVC and CPVC. We have also developed dynamically vulcanized blends of HNBR with polychloroprene, epoxydized natural rubber, chlorobutyl, and carboxylated acrylonitrile-butadiene copolymer. Most of the blends at 75/25 composition have promising properties.

  20. Direct and Indirect Polymer-Polymer Interfacial Slip Measurements in Multilayered Films

    NASA Astrophysics Data System (ADS)

    Lee, Patrick C.; Park, Hee Eon; Macosko, Christopher W.

    2008-07-01

    Significant slip can occur during flow of two immiscible polymers due to reduced entanglements at their interface. The slip is of practical importance because of its effect on morphology and adhesion of these multi-phase materials, such as disordered two-phase blends and multilayer films. In this research, we are investigating the amount of polymer-polymer slip over a range of shear stresses from rheological measurements (i.e., indirect method) and visualization measurements (i.e., direct method) on co-extruded multilayer films. Two types of alternately layered blends were chosen: polypropylene (PP)/polystyrene (PS) and polyethylene (PE)/fluoropolymer (FP) blends. The multilayer samples of both PP/PS and PE/FP blends were prepared in a co-extrusion setup (Zhao and Macosko J. Rheol. 2002) at 200 and 210 °C, respectively, in order to match viscosity and linear viscoelasticity. To study the polymer-polymer interfacial slip over a wide stress range, three types of rheometers were used: an in-line slit-die rheometer, a rotational parallel-disk rheometer, and a sliding-plates rheometer (SPR). It was observed that the viscosity of a multilayer sample is lower than the harmonic average viscosity of two neat polymers for both PP/PS and PE/FP and decreases with the number of layers above a certain critical shear stress. Two visualization techniques, (i) the SPR with a glass top plate and (ii) a high temperature shearing cell, were utilized to prove the slip. The slip velocity (i.e., the amount of macroscopic velocity discontinuity at the interface) with respect to shear stress was calculated from each rheological and visualization methods and compared.

  1. Blending Education and Polymer Science: Semi Automated Creation of a Thermodynamic Property Database.

    PubMed

    Tchoua, Roselyne B; Qin, Jian; Audus, Debra J; Chard, Kyle; Foster, Ian T; de Pablo, Juan

    2016-09-13

    Structured databases of chemical and physical properties play a central role in the everyday research activities of scientists and engineers. In materials science, researchers and engineers turn to these databases to quickly query, compare, and aggregate various properties, thereby allowing for the development or application of new materials. The vast majority of these databases have been generated manually, through decades of labor-intensive harvesting of information from the literature; yet, while there are many examples of commonly used databases, a significant number of important properties remain locked within the tables, figures, and text of publications. The question addressed in our work is whether, and to what extent, the process of data collection can be automated. Students of the physical sciences and engineering are often confronted with the challenge of finding and applying property data from the literature, and a central aspect of their education is to develop the critical skills needed to identify such data and discern their meaning or validity. To address shortcomings associated with automated information extraction, while simultaneously preparing the next generation of scientists for their future endeavors, we developed a novel course-based approach in which students develop skills in polymer chemistry and physics and apply their knowledge by assisting with the semi-automated creation of a thermodynamic property database.

  2. Fine tuning of the PCDTBT-OR:PC71BM blend nanoscale phase separation via selective solvent annealing toward high-performance polymer photovoltaics.

    PubMed

    Meng, Bin; Fang, Gang; Fu, Yingying; Xie, Zhiyuan; Wang, Lixiang

    2013-12-06

    Solution-processable polymer solar cells show great promise for providing a cost-effective route to create lightweight and flexible solar energy conversion devices. The photoactive layer comprising the conjugated polymer donor and fullerene derivative acceptor must be optimized to form bicontinuous nanoscale phase separation in order for efficient exciton dissociation and charge collection due to the short exciton diffusion length of organic semiconductors. The donor polymer poly[9-(heptadecan-9-yl)-9H-carbazole- 2,7-diyl-alt-(5,6-bis(hexyloxy)-4,7-di(thiophen-2- yl)benzo[c][1,2,5]thiadiazole)-5,5-diyl] (PCDTBT-OR) has a deeper highest occupied molecular orbital level compared to its counterpart PCDTBT, and shows promise in increasing the open-circuit voltage and power conversion efficiency (PCE) of polymer solar cells. The phase separation evolution of the PCDTBT-OR:PC71BM blend with various weight ratios under tetrahydrofuran (THF) vapor annealing and its influence on the photovoltaic performance is investigated in detail. It is found that THF vapor annealing can promote the acceptor PC71BM aggregation from the donor PCDTBT-OR matrix to form nanoscale donor/acceptor phase separation for efficient exciton dissociation and charge collection depending on the donor/acceptor weight ratio and the annealing time. The THF vapor-annealed PCDTBT-OR:PC71BM solar cells exhibit remarkable enhancement, with a PCE of 7.01% compared to 3.25% of the as-cast solar cells with the same active layer thickness. This work provides a general methodology to construct nano-interpenetrating networks for homogeneous polymer/fullerene blends and is potentially applicable to the roll-to-roll manufacturing of polymer solar cells.

  3. Fine tuning of the PCDTBT-OR:PC71BM blend nanoscale phase separation via selective solvent annealing toward high-performance polymer photovoltaics

    NASA Astrophysics Data System (ADS)

    Meng, Bin; Fang, Gang; Fu, Yingying; Xie, Zhiyuan; Wang, Lixiang

    2013-12-01

    Solution-processable polymer solar cells show great promise for providing a cost-effective route to create lightweight and flexible solar energy conversion devices. The photoactive layer comprising the conjugated polymer donor and fullerene derivative acceptor must be optimized to form bicontinuous nanoscale phase separation in order for efficient exciton dissociation and charge collection due to the short exciton diffusion length of organic semiconductors. The donor polymer poly[9-(heptadecan-9-yl)-9H-carbazole- 2,7-diyl-alt-(5,6-bis(hexyloxy)-4,7-di(thiophen-2- yl)benzo[c][1,2,5]thiadiazole)-5,5-diyl] (PCDTBT-OR) has a deeper highest occupied molecular orbital level compared to its counterpart PCDTBT, and shows promise in increasing the open-circuit voltage and power conversion efficiency (PCE) of polymer solar cells. The phase separation evolution of the PCDTBT-OR:PC71BM blend with various weight ratios under tetrahydrofuran (THF) vapor annealing and its influence on the photovoltaic performance is investigated in detail. It is found that THF vapor annealing can promote the acceptor PC71BM aggregation from the donor PCDTBT-OR matrix to form nanoscale donor/acceptor phase separation for efficient exciton dissociation and charge collection depending on the donor/acceptor weight ratio and the annealing time. The THF vapor-annealed PCDTBT-OR:PC71BM solar cells exhibit remarkable enhancement, with a PCE of 7.01% compared to 3.25% of the as-cast solar cells with the same active layer thickness. This work provides a general methodology to construct nano-interpenetrating networks for homogeneous polymer/fullerene blends and is potentially applicable to the roll-to-roll manufacturing of polymer solar cells.

  4. An investigation into the use of polymer blends to improve the printability of and regulate drug release from pharmaceutical solid dispersions prepared via fused deposition modeling (FDM) 3D printing.

    PubMed

    Alhijjaj, Muqdad; Belton, Peter; Qi, Sheng

    2016-11-01

    FDM 3D printing has been recently attracted increasing research efforts towards the production of personalized solid oral formulations. However, commercially available FDM printers are extremely limited with regards to the materials that can be processed to few types of thermoplastic polymers, which often may not be pharmaceutically approved materials nor ideal for optimizing dosage form performance of poor soluble compounds. This study explored the use of polymer blends as a formulation strategy to overcome this processability issue and to provide adjustable drug release rates from the printed dispersions. Solid dispersions of felodipine, the model drug, were successfully fabricated using FDM 3D printing with polymer blends of PEG, PEO and Tween 80 with either Eudragit E PO or Soluplus. As PVA is one of most widely used polymers in FDM 3D printing, a PVA based solid dispersion was used as a benchmark to compare the polymer blend systems to in terms of processability. The polymer blends exhibited excellent printability and were suitable for processing using a commercially available FDM 3D printer. With 10% drug loading, all characterization data indicated that the model drug was molecularly dispersed in the matrices. During in vitro dissolution testing, it was clear that the disintegration behavior of the formulations significantly influenced the rates of drug release. Eudragit EPO based blend dispersions showed bulk disintegration; whereas the Soluplus based blends showed the 'peeling' style disintegration of strip-by-strip. The results indicated that interplay of the miscibility between excipients in the blends, the solubility of the materials in the dissolution media and the degree of fusion between the printed strips during FDM process can be used to manipulate the drug release rate of the dispersions. This brings new insight into the design principles of controlled release formulations using FDM 3D printing.

  5. Controlled charge transport by polymer blend dielectrics in top-gate organic field-effect transistors for low-voltage-operating complementary circuits.

    PubMed

    Baeg, Kang-Jun; Khim, Dongyoon; Kim, Juhwan; Han, Hyun; Jung, Soon-Won; Kim, Tae-Wook; Kang, Minji; Facchetti, Antonio; Hong, Sung-Kyu; Kim, Dong-Yu; Noh, Yong-Young

    2012-11-01

    We report here the development of high-performance p- and n-channel organic field-effect transistors (OFETs) and complementary circuits using inkjet-printed semiconducting layers and high-k polymer dielectric blends of poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) and poly(methyl methacrylate) (PMMA). Inkjet-printed p-type polymer semiconductors containing alkyl-substituted thienylenevinylene (TV) and dodecylthiophene (PC12TV12T) and n-type poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-dithiophene)} (P(NDI2OD-T2)) OFETs typically show high field-effect mobilities (μ(FET)) of 0.2-0.5 cm²/(V s), and their operation voltage is effectively reduced to below 5 V by the use of P(VDF-TrFE):PMMA blends. The main interesting result is that the OFET characteristics could be tuned by controlling the mixing ratio of P(VDF-TrFE) to PMMA in the blended dielectric. The μ(FET) of the PC12TV12T OFETs gradually improves, whereas the P(NDI2OD-T2) OFET properties become slightly worse as the P(VDF-TrFE) content increases. When the mixing ratio is optimized, well-balanced hole and electron mobilities of more than 0.2 cm²/(V s) and threshold voltages below ±3 V are obtained at a 7:3 ratio of P(VDF-TrFE) to PMMA. Low-voltage-operated (∼2 V) printed complementary inverters are successfully demonstrated using the blended dielectric and exhibit an ideal inverting voltage of nearly half of the supplied bias, high voltage gains of greater than 25, and excellent noise margins of more than 75% of the ideal values.

  6. Influence of small-molecule material on performance of polymer solar cells based on MEH-PPV:PCBM blend

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Xu, Zheng; Zhang, Fu-Jun; Zhao, Su-Ling; Zhang, Tian-Hui; Gong, Wei; Song, Jing-Lu; Kong, Chao; Yan, Guang; Xu, Xu-Rong

    2010-11-01

    In this work, the influence of a small-molecule material, tris(8-hydroxyquinoline) aluminum (Alq3), on bulk heterojunction (BHJ) polymer solar cells (PSCs) is investigated in devices based on the blend of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). By doping Alq3 into MEH-PPV:PCBM solution, the number of MEH-PPV excitons can be effectively increased due to the energy transfer from Alq3 to MEH-PPV, which probably induces the increase of photocurrent generated by excitons dissociation. However, the low carrier mobility of Alq3 is detrimental to the efficient charge transport, thereby blocking the charge collection by the respective electrodes. The balance between photon absorption and charge transport in the active layer plays a key role in the performance of PSCs. For the case of 5 wt.% Alq3 doping, the device performance is deteriorated rather than improved as compared with that of the undoped device. On the other hand, we adopt Alq3 as a buffer layer instead of commonly used LiF. All the photovoltaic parameters are improved, yielding an 80% increase in power conversion efficiency (PCE) at the optimum thickness (1 nm) as compared with that of the device without any buffer layer. Even for the 5 wt.% Alq3 doped device, the PCE has a slight enhancement compared with that of the standard device after modification with 1 nm (or 2 nm) thermally evaporated Alq3. The performance deterioration of Alq3-doped devices can be explained by the low solubility of Alq3, which probably deteriorates the bicontinuous D—A network morphology; while the performance improvement of the devices with Alq3 as a buffer layer is attributed to the increased light harvesting, as well as blocking the hole leakage from MEH-PPV to the aluminum (Al) electrode due to the lower highest occupied molecular orbital (HOMO) level of Alq3 compared with that of MEH-PPV.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Three-dimensional numerical simulations of lamellar structure via two-step surface-directed phase separation in polymer blend films.

    PubMed

    Yan, Li-Tang; Li, Jialin; Xie, Xu-Ming

    2008-06-14

    Lamellar structure via two-step surface-directed phase separation in polymer blend films is numerically investigated in three-dimensional (3D) space, which is more physically appropriate for the experimental situation than that in two-dimensional (2D) space [L.-T. Yan and X. M. Xie, J. Chem. Phys. 128, 034901 (2008)]. The 3D phase morphology and its evolution dynamics in both critical and off-critical conditions have been studied. The wetting layer formation mechanism during the second quench has been concerned. The effects of noise on the ordered phase structures have also been examined. The simulated results in 3D space give a more certain evidence that the lamellar structure can be induced by the surface or interface when the system is in the equilibration state with very shallow quench depth first and then imposed on a further quench depth in the unstable region of the phase diagram. It is found that the lamellar structure can also be induced in the polymer blends with off-critical condition. The simulated results demonstrate that the formation of the lamellar structure can present two basic processes and obey logarithmic growth law at the initial and metaphase stages. The results also show that a stronger thermal noise corresponds to a smaller region with the lamellar structure.

  9. A Solution Rheology Approach to Resolving Component Dynamics in Miscible A/B Blends: Tube Dilation and Friction Factors of Polymers A and B

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoping; Wang, Shi-Qing

    2000-03-01

    We characterize the component dynamics of model polymer blends using standard rheological methods and well-established reptation theory. To quantitatively evaluate the influence of polymer B on the dynamics of polymer A (and vice versa) as a function of composition and temperature, we develop a novel Solution Rheology Approach by carrying out viscoelastic studies of highly entangled solutions made of (i) long chains of A in short chains of B, (ii) long chains of B in short chains of A. Here the long chains of A and B are respectively the high molecular weight 1,4-polybutadiene and 1,2-polybutadiene. In the solutions of 1,4-PBD in 1,2-oBD and 1,2-PBD in 1,4-oBD, the effect of incorporating the oligomers in PBD is two-fold: dilating the tube diameter in which the long chains reptate and modifying the friction factors associated with the long chains. We demonstrate in this work that the friction factors associated with polymers A and B in their mixtures can be measured explicitly as a function of temperature and composition, directly revealing how each component dynamics behave as a function of temperature at various compositions.

  10. Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Arof, A. K.

    2016-08-01

    In this work, we have investigated the influence of guanine as an organic dopant in dye-sensitized solar cell (DSSC) based on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) polymer blend electrolyte along with binary iodide salts (potassium iodide (KI) and tetrabutylammonium iodide (TBAI)) and iodine (I2). The PVDF-HFP/KI + TBAI/I2, PVDF-HFP/PEO/KI + TBAI/I2 and guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolytes were prepared by solution casting technique using DMF as solvent. The PVDF-HFP/KI + TBAI/I2 electrolyte showed an ionic conductivity value of 9.99 × 10-5 Scm-1, whereas, it was found to be increased to 4.53 × 10-5 Scm-1 when PEO was blended with PVDF-HFP/KI + TBAI/I2 electrolyte. However, a maximum ionic conductivity value of 3.67 × 10-4 Scm-1 was obtained for guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 blend electrolyte. The photovoltaic properties of all these polymer electrolytes in DSSCs were characterized. As a consequence, the power conversion efficiency of the guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC was significantly improved to 4.98% compared with PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC (2.46%). These results revealed that the guanine can be an effective organic dopant to enhance the performance of DSSCs.

  11. Molecular Processing of Polymers with Cyclodextrins

    NASA Astrophysics Data System (ADS)

    Tonelli, Alan E.

    We summarize our recent studies employing the cyclic starch derivatives called cyclodextrins (CDs) to both nanostructure and functionalize polymers. Two important structural characteristics of CDs are taken advantage of to achieve these goals. First the ability of CDs to form noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical with diameters of ˜ 0.5 - 1.0 nm. α-, β-, and γ-CD contain six, seven, and eight α-1,4-linked glucose units, respectively. Warm water washing of polymer-CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serves to remove the host CDs and results in the coalescence of the guest polymers into solid samples. When guest polymers are coalesced from the CD-ICs by removing their host CDs, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. Molecularly mixed, intimate blends of two or more polymers that are normally immiscible can be obtained from their common CD-ICs, and the phase segregation of incompatible blocks can be controlled (suppressed or increased) in CD-IC coalesced block copolymers. In addition, additives may be more effectively delivered to polymers in the form of their crystalline CD-ICs or soluble CD-rotaxanes. Secondly, the many hydroxyl groups attached to the exterior rims of CDs, in addition to conferring water solubility, provide an opportunity to covalently bond them to polymers either during their syntheses or via postpolymerization reactions. Polymers containing CDs in their backbones or attached to their side chains are observed to more readily accept and retain additives, such as dyes and fragrances. Processing with CDs can serve to both nanostructure and functionalize polymers, leading to greater understanding of their behaviors

  12. Ultraporous interweaving electrospun microfibers from PCL-PEO binary blends and their inflammatory responses

    NASA Astrophysics Data System (ADS)

    Li, Yan-Fang; Rubert, Marina; Aslan, Hüsnü; Yu, Ying; Howard, Kenneth A.; Dong, Mingdong; Besenbacher, Flemming; Chen, Menglin

    2014-02-01

    Production of one dimensional nanomaterials with secondary morphology exhibiting unique functions is challenging. Here we report for the first time that a nanoscale immiscible polymer blend solution electrojet can assemble into ultraporous interweaving microfibers. This intriguingly novel morphology originated from a blend of polycaprolactone (PCL) and polyethylene oxide (PEO) in a DCM-DMF mixed solution when the ratio between each component reached a threshold and when the electrospinning parameters were delicately controlled. The morphology, crystallinity, surface chemistry and wettabilities were characterized to understand the mechanism of formation. The interplay of the two semi-crystalline polymers and the pair of solvents/non-solvents with the electrospinning processing parameters was found to be critical for the formation of the unique structure. Furthermore, the interesting combination of biocompatible, biodegradable PCL with protein-resistant PEO motivated us to assess its inflammation responses on the RAW 264.7 macrophage cell line. All fibers were found to be biocompatible with low inflammation potential upon incubation, while compared with pure PCL nanofibers; the unique interweaving microfibers induced a slightly higher inflammatory reaction.Production of one dimensional nanomaterials with secondary morphology exhibiting unique functions is challenging. Here we report for the first time that a nanoscale immiscible polymer blend solution electrojet can assemble into ultraporous interweaving microfibers. This intriguingly novel morphology originated from a blend of polycaprolactone (PCL) and polyethylene oxide (PEO) in a DCM-DMF mixed solution when the ratio between each component reached a threshold and when the electrospinning parameters were delicately controlled. The morphology, crystallinity, surface chemistry and wettabilities were characterized to understand the mechanism of formation. The interplay of the two semi-crystalline polymers and the

  13. Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation-Crosslinked Poly (Vinyl Alcohol)-Based Solid Polymer Electrolytes Blended With LiOH{center_dot}H{sub 2}O Salt

    SciTech Connect

    Khafagy, Rasha M.; Madani, M.; Badr, Y. A.

    2008-09-23

    Solid polymer electrolytes based on poly(vinyl alcohol)(PVA) blended with different concentrations of LiOH{center_dot}H{sub 2}O salt were prepared using casting and {gamma}-irradiation techniques. The structure and blending of the poly-electrolytes were studied by X-ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and these melting points change with the salt content. All characterizing techniques revealed the blend formation between LiOH{center_dot}H{sub 2}O salt and the polymer matrix. To account for the performance of the prepared solid polymer electrolytes, thermally stimulated depolarization current (TSDC) studies of the prepared blends were done. Short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm{sup -1} have been analyzed in the temperature range 300-410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly-blend system. The prepared solid polymer electrolytes showed good charge storage capacity, and moderate current density values near the ambient.

  14. Chitosan-PLGA polymer blends as coatings for hydroxyapatite nanoparticles and their effect on antimicrobial properties, osteoconductivity and regeneration of osseous tissues.

    PubMed

    Ignjatović, Nenad; Wu, Victoria; Ajduković, Zorica; Mihajilov-Krstev, Tatjana; Uskoković, Vuk; Uskoković, Dragan

    2016-03-01

    Composite biomaterials comprising nanostructured hydroxyapatite (HAp) have an enormous potential for natural bone tissue reparation, filling and augmentation. Chitosan (Ch) as a naturally derived polymer has many physicochemical and biological properties that make it an attractive material for use in bone tissue engineering. On the other hand, poly-D,L-lactide-co-glycolide (PLGA) is a synthetic polymer with a long history of use in sustained drug delivery and tissue engineering. However, while chitosan can disrupt the cell membrane integrity and may induce blood thrombosis, PLGA releases acidic byproducts that may cause tissue inflammation and interfere with the healing process. One of the strategies to improve the biocompatibility of Ch and PLGA is to combine them with compounds that exhibit complementary properties. In this study we present the synthesis and characterization, as well as in vitro and in vivo analyses of a nanoparticulate form of HAp coated with two different polymeric systems: (a) Ch and (b) a Ch-PLGA polymer blend. Solvent/non-solvent precipitation and freeze-drying were used for synthesis and processing, respectively, whereas thermogravimetry coupled with mass spectrometry was used for phase identification purposes in the coating process. HAp/Ch composite particles exhibited the highest antimicrobial activity against all four microbial strains tested in this work, but after the reconstruction of the bone defect they also caused inflammatory reactions in the newly formed tissue where the defect had lain. Coating HAp with a polymeric blend composed of Ch and PLGA led to a decrease in the reactivity and antimicrobial activity of the composite particles, but also to an increase in the quality of the newly formed bone tissue in the reconstructed defect area.

  15. Electrified Microscopic and Conventional Interfaces between Two Immiscible Electrolyte Solutions

    DTIC Science & Technology

    1991-06-24

    2 INTRODUCTION TO ELECTRIFIED LIQUID / LIQUID INTERFACES Interfaces between two immiscible solutions containing ionic species are of interest to a wide...if necessary and identify by block number) PELD I GPOUP SUB GROUP MICRODOMAINS, MICELES, LIQUID - LIQUID ELECTROCHEMISTRY, IMMISCIBLE ELECTROLYTES...between immiscible phases bridges the field of heterogeneous electrode electrochemistry and that of homogeneous solution chemistry. Early work on liquid

  16. Observation of Banded Spherulites in Pure poly(L-lactide) and its Miscible Blends with Amorphous Polymers

    SciTech Connect

    Xu,J.; Guo, B.; Zhou, J.; Li, L.; Wu, J.; Kowalczuk, M.

    2005-01-01

    Banded spherulites of pure poly(l-lactide) (PLLA) were observed via the 'crystallization after annealing' procedure, while only common spherulites were obtained via the 'direct isothermal crystallization' procedure. Wide angle X-ray diffraction revealed that the two types of spherulites had the same crystal lattice of a-modification. Atomic force microscopy demonstrated that the alternative negative and positive birefringent bands resulted from the alternative edge-on and flat-on lamellar orientations in the spherulites. Furthermore, the effect of thermal history on the spherulitic morphology was investigated in details. The PLLA samples melted for longer time or those with lower melting point were more likely to form banded spherulites. The possibility that the change of molecular weight was a determining factor of banding was excluded by the results on differently prepared samples with the same molecular weight. Therefore, we conclude that it was complete melting of the crystalline residues that favored formation of PLLA banded spherulites. Blending of PLLA with atactic poly(d, l-lactide) or poly[(R, S)-3-hydroxybutyrate], led to reduced band spacing. Effect of blending on the chain mobility, spherulite growth kinetics, supercooling and lamellar surface energy was quantitatively studied, which suggests that the blending-reduced band spacing cannot be attributed to the above factors. Therefore, there are other blending-relevant factors leading to the reduced band spacing.

  17. Centro-Apical Self-Organization of Organic Semiconductors in a Line-Printed Organic Semiconductor: Polymer Blend for One-Step Printing Fabrication of Organic Field-Effect Transistors.

    PubMed

    Lee, Su Jin; Kim, Yong-Jae; Yeo, So Young; Lee, Eunji; Lim, Ho Sun; Kim, Min; Song, Yong-Won; Cho, Jinhan; Lim, Jung Ah

    2015-09-11

    Here we report the first demonstration for centro-apical self-organization of organic semiconductors in a line-printed organic semiconductor: polymer blend. Key feature of this work is that organic semiconductor molecules were vertically segregated on top of the polymer phase and simultaneously crystallized at the center of the printed line pattern after solvent evaporation without an additive process. The thickness and width of the centro-apically segregated organic semiconductor crystalline stripe in the printed blend pattern were controlled by varying the relative content of the organic semiconductors, printing speed, and solution concentrations. The centro-apical self-organization of organic semiconductor molecules in a printed polymer blend may be attributed to the combination of an energetically favorable vertical phase-separation and hydrodynamic fluids inside the droplet during solvent evaporation. Finally, a centro-apically phase-separated bilayer structure of organic semiconductor: polymer blend was successfully demonstrated as a facile method to form the semiconductor and dielectric layer for OFETs in one- step.

  18. Centro-Apical Self-Organization of Organic Semiconductors in a Line-Printed Organic Semiconductor: Polymer Blend for One-Step Printing Fabrication of Organic Field-Effect Transistors

    PubMed Central

    Jin Lee, Su; Kim, Yong-Jae; Young Yeo, So; Lee, Eunji; Sun Lim, Ho; Kim, Min; Song, Yong-Won; Cho, Jinhan; Ah Lim, Jung

    2015-01-01

    Here we report the first demonstration for centro-apical self-organization of organic semiconductors in a line-printed organic semiconductor: polymer blend. Key feature of this work is that organic semiconductor molecules were vertically segregated on top of the polymer phase and simultaneously crystallized at the center of the printed line pattern after solvent evaporation without an additive process. The thickness and width of the centro-apically segregated organic semiconductor crystalline stripe in the printed blend pattern were controlled by varying the relative content of the organic semiconductors, printing speed, and solution concentrations. The centro-apical self-organization of organic semiconductor molecules in a printed polymer blend may be attributed to the combination of an energetically favorable vertical phase-separation and hydrodynamic fluids inside the droplet during solvent evaporation. Finally, a centro-apically phase-separated bilayer structure of organic semiconductor: polymer blend was successfully demonstrated as a facile method to form the semiconductor and dielectric layer for OFETs in one- step. PMID:26359068

  19. Amorphous phase separation in crystallizable polymer blends based on poly (aryl ether ketones) and poly (ether imide)

    SciTech Connect

    Kalika, D.S.; Bristow, J.F.

    1996-12-31

    The morphology of a series of miscible crystallizable blends based on poly (aryl ether ketones) [PAEK] and poly (ether imide) [PEI] has been investigated as a function of blend composition and crystallization condition by dielectric relaxation spectroscopy. For blends of poly (ether ether ketone) [PEEK] and PEI, dielectric scans of the crystallized samples reveal two glass-rubber relaxations corresponding to the coexistence of a mixed interlamellar amorphous phase, and a pure PEI phase located in interfibrillar/interspherulitic regions. The exclusion of a significant fraction of PEI outside of the crystal lamellae reflects a fundamental change in the nature of interaction between the interlamellar PEEK segments and the PEI chains owing to the constraints imposed on the PEEK segments by the crystal surfaces. The degree of PEI exclusion is dependent upon kinetic factors, i.e. the rate of PEEK crystallization relative to the rate of PEI diffusion away from the advancing crystal front. As a result, lower crystallization temperatures lead to an increase in the amount of PEI trapped in the interlamellar regions. In this work, the morphological characteristics of the PEEK/PEI blends are compared with those of blends comprised of poly (ether ketone ketone) [PEKK] and PEI. The introduction of the {open_quotes}kinked{close_quote} isophthalate moiety in the PEKK backbone has been shown to disrupt the persistence of order at the crystal-amorphous interface, and thereby leads to a reduction in the degree of constraint imposed by the crystal lamellae on the amorphous (interlamellar) PEKK segments. The impact of this reduction in crystalline constraint on the nature of the PEKK/PEI intersegmental interactions and the corresponding PEI segregation is discussed.

  20. Honeycomb Films with Core-Shell Dispersed Phases Prepared by the Combination of Breath Figures and Phase Separation Process of Ternary Blends.

    PubMed

    Del Campo, A; de León, A S; Rodríguez-Hernández, J; Muñoz-Bonilla, A

    2017-03-21

    Herein, we propose a strategy to fabricate core-shell microstructures ordered in hexagonal arrays by combining the breath figures approach and phase separation of immiscible ternary blends. This simple strategy to fabricate these structures involves only the solvent casting of a ternary polymer blend under moist atmosphere, which provides a facile and low-cost fabrication method to obtain the porous structures with a core-shell morphology. For this purpose, blends consisting of polystyrene (PS) as a major component and PS40-b-P(PEGMA300)48 amphiphilic copolymer and polydimethylsiloxane (PDMS) as minor components were dissolved in tetrahydrofuran and cast onto glass wafers under humid conditions, 70% of relative humidity. The resulting porous morphologies were characterized by optical and confocal Raman microscopy. In particular, confocal Raman results demonstrated the formation of core-shell morphologies into the ordered pores, in which the PS forms the continuous matrix, whereas the other two phases are located into the cavities (PDMS is the core while the amphiphilic copolymer is the shell). Besides, by controlling the weight ratio of the polymer blends, the structural parameters of the porous structure such as pore diameter and the size of the core can be effectively tuned.

  1. Effectiveness of organoclays as compatibilizers for multiphase polymer blends – A sustainable route for the mechanical recycling of co-mingled plastics

    SciTech Connect

    Causa, Andrea; Acierno, Domenico; Filippone, Giovanni; Mistretta, Maria Chiara

    2014-05-15

    We prepare and characterize multiphase systems in which small amounts of recycled polymer, namely polyethylene terephtalate (PET) ground from waste bottles, are dispersed in a co-continuous blend of high-density polyethylene (HDPE) and polypropylene (PP). Some of such ternary systems are also filled with plate-like clay nanoparticles with different polarities, in order to assess their influence on the morphology and mechanical behaviour of the blends. On the basis of preliminary wettability considerations and inspections by means of scanning electron microscopy (SEM), the PET is found to preferentially locate within the PP phase. Such a positioning is desirable in order to minimize the presence of multiple interfaces, which is one of the major issues in the recycling process of co-mingles plastics. By means of SEM, dynamic-mechanical analysis and tensile tests we show that the addition of a filler with low polarity, which locates at the PET-matrix interface, has relevant implications on the structure and properties of the ternary systems, refining their morphology at the micro-scale and enhancing their high-temperature mechanical behaviour.

  2. Effectiveness of organoclays as compatibilizers for multiphase polymer blends - A sustainable route for the mechanical recycling of co-mingled plastics

    NASA Astrophysics Data System (ADS)

    Causa, Andrea; Mistretta, Maria Chiara; Acierno, Domenico; Filippone, Giovanni

    2014-05-01

    We prepare and characterize multiphase systems in which small amounts of recycled polymer, namely polyethylene terephtalate (PET) ground from waste bottles, are dispersed in a co-continuous blend of high-density polyethylene (HDPE) and polypropylene (PP). Some of such ternary systems are also filled with plate-like clay nanoparticles with different polarities, in order to assess their influence on the morphology and mechanical behaviour of the blends. On the basis of preliminary wettability considerations and inspections by means of scanning electron microscopy (SEM), the PET is found to preferentially locate within the PP phase. Such a positioning is desirable in order to minimize the presence of multiple interfaces, which is one of the major issues in the recycling process of co-mingles plastics. By means of SEM, dynamic-mechanical analysis and tensile tests we show that the addition of a filler with low polarity, which locates at the PET-matrix interface, has relevant implications on the structure and properties of the ternary systems, refining their morphology at the micro-scale and enhancing their high-temperature mechanical behaviour.

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

    PubMed

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

    2011-12-27

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

  4. Alternative polymer separation technology by centrifugal force in a melted state

    SciTech Connect

    Dobrovszky, Károly; Ronkay, Ferenc

    2014-11-15

    Highlights: • Waste separation should take place at high purity. • Developed a novel, alternative separation method, where the separation occurred in a melted state by centrifugal forces. • Possibility of separation two different plastics into neat fractions. • High purity fractions were established at granulates and also at prefabricated blend. • Results were verified by DSC, optical microscopy and Raman spectroscopy. - Abstract: In order to upgrade polymer waste during recycling, separation should take place at high purity. The present research was aimed to develop a novel, alternative separation opportunity, where the polymer fractions were separated by centrifugal force in melted state. The efficiency of the constructed separation equipment was verified by two immiscible plastics (polyethylene terephthalate, PET; low density polyethylene, LDPE), which have a high difference of density, and of which large quantities can also be found in the municipal solid waste. The results show that the developed equipment is suitable not only for separating dry blended mixtures of PET/LDPE into pure components again, but also for separating prefabricated polymer blends. By this process it becomes possible to recover pure polymer substances from multi-component products during the recycling process. The adequacy of results was verified by differential scanning calorimetry (DSC) measurement as well as optical microscopy and Raman spectroscopy.

  5. The effects of mechanical milling and alloying on poly(ethylene terephthalate) and its blends with Vectra(TM) liquid crystalline polymer

    NASA Astrophysics Data System (ADS)

    Bai, Changhe

    Poly(ethylene terephthalate) (PET) has been subjected to high-energy ball-milling (mechanical milling) performed at three different temperatures. The resulting milled powder is characterized by molecular weight measurements, differential scanning calorimetry and wide-angle x-ray scattering. Regardless of the initial degree of crystallinity or milling temperature employed, mechanical milling of PET yields an "oriented amorphous" morphology in which the PET chains are aligned but rotationally disordered, which explains the amorphous wide-angle x-ray pattern from mechanically milled (MM) PET and the small, broad crystallization exotherm. and a large melting endotherm. Evidence is also presented to suggest that extended-chain crystals of PET are produced after crystallization of MM PET. Mechanical alloying of PET and a liquid crystalline polymer VectraTM has been performed at either room temperature or cryogenic temperature. Morphological studies using optical microscopy, TEM, and x-ray microscopy reveal that intimate mixing of PET and Vectra on a sub-micrometer scale has been achieved by mechanical alloying. No prior reports of preparing PET/Vectra blends on such a fine scale have been documented, which shows the efficacy of solid state mixing via mechanical alloying. The milled alloy is thermally unstable and severe phase separation ensues during post thermal processing. The scale of mixing can be largely preserved by compaction at a temperature below the melting point of either constituent polymer, which gives rise to rule-of-mixtures behavior in alloy hardness. Vectra does not function as a nucleation agent for PET, as evidenced from isothermal crystallization. Hot-melt adhesives may be a potential application for MA PET/Vectra blends. The scale of mixing, however, does not correlate with interfacial fracture toughness.

  6. Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy.

    PubMed

    Masters, Robert C; Pearson, Andrew J; Glen, Tom S; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M; Lidzey, David G; Rodenburg, Cornelia

    2015-04-24

    The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.

  7. Hybrid solar cells of conjugated polymers metal-oxide nanocrystals blends; state of the art and future research challenges in Indonesia

    NASA Astrophysics Data System (ADS)

    Bahtiar, Ayi

    2013-09-01

    Ever-increasing world energy demand, depleting non-renewable energy resources and disruptive climate change due to greenhouse gases has aroused much interest in alternative renewable energy sources. Solar energy is one of the best available alternatives, for it is both abundant and clean. Solar cell is an effective device for converting solar energy into electricity. Indonesia is located on the equator where the sunlight is always available in abundance throughout the year; therefore solar cell would become the main source of electrical energy in Indonesia. However, the high cost of inorganic solar cells in spite of their high power conversion efficiency (PCE) has been a major constrain for their mass utilization in Indonesia. The only way to reduce the cost of production and installation is to find other materials which offer low-cost and easy processing into solar cells. Polymer solar cells have been intensively investigated for high performance and low-cost solar cells. Today, 9-11% power conversion efficiency (PCE) of small area polymer solar cells and 2-4% PCE of large area or module solar cells are already achieved. However, for practical application and mass production, 10% or higher PCE of module solar cells is highly required. The main strategic issue for improving the PCE is to use blend of conjugated polymer-metal oxide nanocrystals as active materials for hybrid solar cells, due to the good combination of the versatile solution processability of conjugated polymers and high charge carrier mobility of metal-oxide nanocrystals. In this paper, current development of hybrid solar cells worldwide and future research challenges in Indonesia will be discussed.

  8. Ternary-Blend Polymer Solar Cells Combining Fullerene and Nonfullerene Acceptors to Synergistically Boost the Photovoltaic Performance.

    PubMed

    Lu, Heng; Zhang, Jicheng; Chen, Jianya; Liu, Qian; Gong, Xue; Feng, Shiyu; Xu, Xinjun; Ma, Wei; Bo, Zhishan

    2016-11-01

    A ternary-blend strategy is presented to surmount the shortcomings of both fullerene derivatives and nonfullerene small molecules as acceptors for the first time. The optimal ternary device shows a high power conversion efficiency (PCE) of 10.4%. Moreover, a significant enhancement in PCE (≈35%) relative to both of the binary reference devices, which has never been achieved before in high-efficiency ternary devices, is demonstrated.

  9. Length Scales of Local Glass Transition Temperature Gradients Near Soft and Hard Polymer-Polymer Interfaces

    NASA Astrophysics Data System (ADS)

    Baglay, Roman; Roth, Connie

    Polymer-polymer interfaces are ubiquitous in polymer blends and block copolymers, while opening up another avenue for the study of interfacial perturbations to the local glass transition temperature Tg(z). We have previously reported the full local Tg(z) profile across a glassy-rubbery polymer interface between polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA), an 80 K difference in bulk Tg [Baglay & Roth, J Chem Phys 2015, 143, 111101]. By using local fluorescence measurements, we revealed how the Tg(z) profile extends hundreds of nanometers away from the interface showing an asymmetric behavior penetrating deeper into the glassy PS side relative to the composition profile. Here, we extend these measurements to investigate how the local Tg profile in PS varies when in contact with a variety of immiscible polymers whose Tgs vary between +90 K and -80 K relative to the bulk Tg of PS, so-called hard vs. soft confinement. The data reveal that the onset of local Tg deviation from bulk in PS occurs at two distinct length scales, which depend on whether PS is the low Tg component (hard confinement) or the high Tg component (soft confinement). In addition, we explore the influence of finite system size on the range of dynamics by the introduction of periodic boundary conditions, as is commonly encountered in computer simulations or block copolymer systems.

  10. Measuring Interfacial Tension Between Immiscible Liquids

    NASA Technical Reports Server (NTRS)

    Rashidnia, Nasser; Balasubramaniam, R.; Delsignore, David M.

    1995-01-01

    Glass capillary tube technique measures interfacial tension between two immiscible liquids. Yields useful data over fairly wide range of interfacial tensions, both for pairs of liquids having equal densities and pairs of liquids having unequal densities. Data on interfacial tensions important in diverse industrial chemical applications, including enhanced extraction of oil; printing; processing foods; and manufacture of paper, emulsions, foams, aerosols, detergents, gel encapsulants, coating materials, fertilizers, pesticides, and cosmetics.

  11. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Ng, Lee H.; Sadoway, Donald R.

    1987-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by iamging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  12. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Sadoway, D. R.

    1986-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by imaging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  13. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    SciTech Connect

    Costa, Luciano T.

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li{sup +} coordination and transportation were studied in the ternary electrolyte system, i.e., PEO{sub 16}LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  14. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend.

    PubMed

    Costa, Luciano T; Sun, Bing; Jeschull, Fabian; Brandell, Daniel

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li(+) coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  15. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    NASA Astrophysics Data System (ADS)

    Costa, Luciano T.; Sun, Bing; Jeschull, Fabian; Brandell, Daniel

    2015-07-01

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li+ coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSIṡ1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  16. Morphologic improvement of the PBDTTT-C and PC71BM blend film with mixed solvent for high-performance inverted polymer solar cells.

    PubMed

    Chen, Hsin-Yi; Lin, Shang-Hong; Sun, Jen-Yu; Hsu, Chi-Hsing; Lan, Shiang; Lin, Ching-Fuh

    2013-12-06

    Tracing the evolution of the bulk heterojunction structure, a dramatic promotion in the efficiency of polymer solar cells has been obtained in recent years. The active layer morphology of low-bandgap polymer solar cells is one of the critical factors for high-efficiency performance. In the past, the relationship between morphology improvement and the device's characteristics (such as efficiency, fill factor and short-circuit current) in low-bandgap polymer solar cells has been studied intensively with regards to the conventional structure. Here we demonstrate the morphologic improvement of the poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b;4,5-b']dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiopene)-2,6-diyl]/[6,6]-phenyl C71 butyric acid methyl ester (PBDTTT-C/PC71BM) blend film for inverted solar cells. By utilizing a mixed solvent of dichlorobenzene/chlorobenzene with (1,8-diiodooctane) additives, the device efficiency can be significantly enhanced, from 0.92% to 4.43%. This enhancement is attributed to active layer morphologic improvement promoting carrier transport. Furthermore, the thickness optimization of the active layer and the electron blocking layer MoO3 further contributes to efficiency. The device performance could be achieved with an efficiency as high as 5.35%, an open-circuit voltage of 0.70 V, a short-circuit current density of 13.5 mA cm(-2), and a fill factor of 57%.

  17. Approach for achieving flame retardancy while retaining physical properties in a compatible polymer matrix

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor)

    2011-01-01

    The invention provides polymer blends containing polyhydroxyamide and one or more flammable polymers. The polymer blends are flame retardant and have improved durability and heat stability compared to the flammable polymer portion of the blends. Articles containing the polymer blends are also provided.

  18. Approach for achieving flame retardancy while retaining physical properties in a compatible polymer matrix

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor)

    2007-01-01

    The invention provides polymer blends containing polyhydroxyamide and one or more flammable polymers. The polymer blends are flame retardant and have improved durability and heat stability compared to the flammable polymer portion of the blends. Articles containing the polymer blends are also provided.

  19. Analysis of Flame Retardancy in Polymer Blends by Synchrotron X-ray K-edge Tomography and Interferometric Phase Contrast Movies.

    PubMed

    Olatinwo, Mutairu B; Ham, Kyungmin; McCarney, Jonathan; Marathe, Shashidhara; Ge, Jinghua; Knapp, Gerry; Butler, Leslie G

    2016-03-10

    Underwriters Laboratories 94 test bars have been imaged with X-ray K-edge tomography between 12 and 32 keV to assess the bromine and antimony concentration gradient across char layers of partially burnt samples. Phase contrast tomography on partially burnt samples showed gas bubbles and dark-field scattering ascribed to residual blend inhomogeneity. In addition, single-shot grating interferometry was used to record X-ray movies of test samples during heating (IR and flame) intended to mimic the UL 94 plastics flammability test. The UL 94 test bars were formulated with varying concentrations of a brominated flame retardant, Saytex 8010, and a synergist, Sb2O3, blended into high-impact polystyrene (HIPS). Depending on the sample composition, samples will pass or fail the UL 94 plastics flammability test. Tomography and interferometry imaging show differences that correlate with UL 94 performance. Key features such as char layer, gas bubble formation, microcracks, and dissolution of the flame retardant in the char layer regions are used in understanding the efficiency of the flame retardant and synergist. The samples that pass the UL 94 test have a thick, highly visible char layer as well as an interior rich in gas bubbles. Growth of gas bubbles from flame-retardant thermal decomposition is noted in the X-ray phase contrast movies. Also noteworthy is an absence of bubbles near the burning surface of the polymer; dark-field images after burning suggest a microcrack structure between interior bubbles and the surface. The accepted mechanism for flame retardant activity includes free radical quenching in the flame by bromine and antimony species. The imaging supports this as well as provides a fast inspection of other parameters, such as viscosity and surface tension.

  20. Ordered fibrillar morphology of donor-acceptor conjugated copolymers at multiple scales via blending with flexible polymers and solvent vapor annealing: insight into photophysics and mechanism.

    PubMed

    Wang, Haiyang; Liu, Jiangang; Xu, Yaozhuo; Yu, Xinhong; Xing, Rubo; Han, Yanchun

    2014-01-28

    The ordered, aligned fibrillar morphology at multiple scales of a donor-acceptor (D-A) conjugated copolymer of 3,6-bis-(thiophen-2-yl)-N,N'-bis(2-octyl-1-dodecyl)-1,4-dioxo-pyrrolo[3,4-c]pyrrole and thieno[3,2-b]thiophene (PDBT-TT) was prepared via blending with flexible polymers (PS13.7k, PDBT-TT/PS = 1/10 w/w) followed by chloroform (CF) solvent vapor annealing (SVA) for 24 h. The aligned fibrillar bundles were of about 500 nm width, consisting of parallel aligned nanofibrils of ab. 10 nm width. It was found that the direction of backbones in nanofibrils was parallel to the long axis of nanofibrils, which implied an intense intra-chain conjugation associated with extended backbones and J-aggregation of PDBT-TT. This ordered morphology corresponded to the characteristic photophysical features of (i) red-shifted absorption arising from J-aggregation, (ii) larger Davydov splitting, (iii) the prevailing absorbance of J-aggregation over H-aggregation in its UV-Vis spectrum and (iv) more red-shifted max photoluminescence emission, compared with the films prepared via the other methods. By investigating the Raman spectra and XRD profiles, it is proposed that the origin of the best morphological and photophysical order is the combination of blending and SVA. The limited and "flexible" space formed due to phase separation between PDBT-TT and PS facilitated the motion of rigid PDBT-TT chains and promoted their stacking order as templates, and CF vapor assisted the conformational transition of chains to more "coil-like" to help them reorganize in a thermodynamic stable way.

  1. Low-voltage polymer/small-molecule blend organic thin-film transistors and circuits fabricated via spray deposition

    SciTech Connect

    Hunter, By Simon; Anthopoulos, Thomas D.; Ward, Jeremy W.; Jurchescu, Oana D.; Payne, Marcia M.; Anthony, John E.

    2015-06-01

    Organic thin-film electronics have long been considered an enticing candidate in achieving high-throughput manufacturing of low-power ubiquitous electronics. However, to achieve this goal, more work is required to reduce operating voltages and develop suitable mass-manufacture techniques. Here, we demonstrate low-voltage spray-cast organic thin-film transistors based on a semiconductor blend of 2,8-difluoro- 5,11-bis (triethylsilylethynyl) anthradithiophene and poly(triarylamine). Both semiconductor and dielectric films are deposited via successive spray deposition in ambient conditions (air with 40%–60% relative humidity) without any special precautions. Despite the simplicity of the deposition method, p-channel transistors with hole mobilities of >1 cm{sup 2}/Vs are realized at −4 V operation, and unipolar inverters operating at −6 V are demonstrated.

  2. Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

    NASA Astrophysics Data System (ADS)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A. K.

    2016-10-01

    This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I2) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C3N4/TiO2 composite as photoanode. The g-C3N4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C3N4/TiO2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C3N4/TiO2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10-5 and 1.87×10-4 Scm-1 respectively. The UV-vis absorption spectroscopy was carried out for the pure and different wt% of g-C3N4/TiO2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C3N4/TiO2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C3N4/TiO2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C3N4/TiO2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs.

  3. Simultaneous Prediction of Upper and Lower Critical Temperatures in Polymer Solutions Using a Constant Parameter Set

    NASA Astrophysics Data System (ADS)

    Clark, Elizabeth; Lipson, Jane

    2009-03-01

    Polymer solutions commonly exhibit phase separation and so the ability to predict temperatures and compositions associated with immiscibility is advantageous to experimentalists. We have been applying a simple lattice model that is capable of capturing both upper (UCST) and lower critical solution temperature (LCST) type phase behavior for polymer blends. Most recently we have become interested in mixtures which simultaneously exhibit both types of phase behavior. Examples include polyisobutylene (PIB) in pure and mixed solvents, and cyclohexane/polystyrene mixtures. We have found that with a single set of temperature-independent parameters the lattice theory is capable of capturing all the physics of these solutions; in addition we discuss conditions under which 'hourglass' phase diagrams result.

  4. Multistability, ionic doping, and charge dynamics in electrosynthesized polypyrrole, polymer-nanoparticle blend nonvolatile memory, and fixed p-i-n junction polymer light-emitting electrochemical cells

    NASA Astrophysics Data System (ADS)

    Simon, Daniel Theodore

    A variety of factors make semiconducting polymers a fascinating alternative for both device development and new areas of fundamental research. Among these are solution processability, low cost, flexibility, and the strong dependence of conduction on the presence of charge compensating ions. With the lack of a complete fundamental understanding of the materials, and the growing demand for novel solutions to semiconductor device design, research in the field can take many, often multifaceted, routes. Due to ion-mediated conduction and versatility of fabrication, conducting polymers can provide a route to the study of neural signaling. In the first of three research topics presented, junctions of polypyrrole electropolymenzed on microelectrode arrays are demonstrated. Indi vidual junctions, when synthesized in a three-electrode configuration, exhibit current switching behavior analogous to neural weighting. Junctions copolymerized with thiophene exhibit current rectification and the nonlinear current-voltage behavior requisite for complex neural systems. Applications to larger networks, and eventual use in analysis of signaling, are discussed. In the second research topic, nonvolatile resistive memory consisting of gold nanoparticles embedded in a polymer film is examined using admittance spectroscopy. The frequency dependence of the devices indicates space-charge-limited transport in the high-conductivity "on" state, and similar transport in the lower-conductivity "off' state. Furthermore, a larger do capacitance of the on state indicates that a greater amount of filling of midgap trap levels introduced by the nanoparticles increases conductivity, leading to the memory effect. Implications on the question as to whether or not the on state is the result of percolation pathways is discussed. The third and final research topic is a presentation of enhanced efficiency of polymer light-emitting electrochemical cells (LECs) by means of forming a doping self

  5. Junctions between metals and blends of conducting and biodegradable polymers (PLLA-PPy and PCL-PPy).

    PubMed

    Boutry, C M; Müller, M; Hierold, C

    2012-08-01

    The junctions between newly developed biodegradable conducting polymers (polylactide-polypyrrole PLLA-PPy and polycaprolactone-polypyrrole PCL-PPy) and metal electrodes (Au, Au/Cu, Ag, Ag/Cu, Cu, Cr/Au/Cu, Pd/Au/Cu, Pt/Au/Cu) were studied. The objective was to determine the composite/metal combination having the lowest possible contact resistance and ohmic characteristics. In a first step, different surface treatments, adhesion and metal layers were tested in order to evaluate the contact resistance. Then the current-voltage (IV) characteristics were measured and both ohmic and rectifying behaviour were observed depending on the polymer/metal junctions investigated. The surface treatments studied included an argon sputtering step and a grinding of the polymer surface with the objective of improving the contact between the metal electrode and the polymer. It was found that the most favourable conditions resulted from a process flow without argon sputtering, without grinding for PLLA-PPy and with a slight grinding for PCL-PPy. Moreover the most favourable metal electrodes for PLLA-PPy were Pd/Au/Cu, while the best compromise for PCL-PPy was to use Au/Cu. For the rectifying polymer/metal junctions, the standard thermionic emission model modified with a series resistance was successfully applied to the measured current-voltage IV characteristics. The saturation current density J0, series resistance R, ideality diode factor n and barrier height φB were investigated. The Chot functions were computed for each rectifying junction and the corresponding threshold voltages were calculated. Finally the conductivity of both composites was evaluated as a function of temperature in the range of 30 °C to 80 °C. For PLLA-PPy a decrease of the resistivity was observed when the temperature was increasing, while no clearly recognisable pattern was identified for PCL-PPy in this temperature range. The electrical conductivity of the PLLA-PPy samples was found to follow the empirical

  6. Synthesis and phase behavior of end-functionalized associating polymers

    NASA Astrophysics Data System (ADS)

    Wrue, Michelle H.

    chemical cleavage of the end-groups resulted in Tgs near those observed for polymer standards of comparable molecular weight. Aggregation of UPy end-groups in solution was observed using gel permeation chromatography. Aggregation was only observed for telechelic samples of low molecular weight, indicating that the aggregation of end-groups is dependent upon the concentration of the end-groups. The effect of UPy end-groups on blend miscibility was studied in solution using laser light scattering and in the melt state was using laser light scattering, optical microscopy and differential scanning calorimetry. The incorporation of associating groups onto one end of either blend component decreases miscibility relative to unfunctionalized parent blends. Lower miscibility was also observed for blends in which both components were mono-functionalized with associating end-groups. The largest decrease in miscibility was observed for blends containing telechelic UPy-functionalized polymers, which were immiscible across the entire composition range.

  7. Toxicological responses in SW mice exposed to inhaled pyrolysates of polymer/tobacco mixtures and blended tobacco.

    PubMed

    Werley, Michael S; Lee, K Monika; Lemus-Olalde, Ranulfo

    2009-12-01

    Modern cigarette manufacturing is highly automated and produces millions of cigarettes per day. The potential for small inclusions of non-cigarette materials such as wood, cardboard packaging, plastic, and other materials exists as a result of bulk handling and high-speed processing of tobacco. Many non-tobacco inclusions such as wood, paper, and cardboard would be expected to yield similar pyrolysis products as a burning cigarette. The aircraft industry has developed an extensive literature on the pyrolysis products of plastics, however, that have been reported to yield toxic by-products upon burning, by-products that have been lethal in animals and humans upon acute exposure under some exposure conditions. Some of these smoke constituents have also been reported in cigarette smoke. Five synthetic polymers, nylon 6, acrylonitrile-butadiene-styrene (ABS), nylon 12, nylon 6,6, and acrylonitrile-butadiene (AB), and the natural polymer wool were evaluated by adding them to tobacco at a 3, 10, and 30% inclusion level and then pyrolyzing the mixture. The validated smoke generation and exposure system have been described previously. We used the DIN 53-436 tube furnace and nose-only exposure chamber in combination to conduct exposures in Swiss-Webster mice. Potentially useful biological endpoints for predicting hazards in humans included sensory irritation and pulmonary irritation, respiratory function, clinical signs, body weights, bronchoalveolar lavage (BAL) fluid analysis, carboxyhemoglogin, blood cyanide concentrations, and histopathology of the respiratory tract. Chemical analysis of selected smoke constituents in the test atmosphere was also performed in order to compare the toxicological responses with exposure to the test atmospheres. Under the conditions of these studies, biological responses considered relevant and useful for prediction of effects in humans were found for sensory irritation, body weights, BAL fluid analysis, and histopathology of the nose

  8. Immiscible poly(lactic acid)/poly(ε-caprolactone) for temporary implants: Compatibility and cytotoxicity.

    PubMed

    Finotti, Pablo F M; Costa, Lidiane C; Capote, Ticiana S O; Scarel-Caminaga, Raquel M; Chinelatto, Marcelo A

    2017-01-31

    This manuscript focuses on the effect of the addition of a low molecular weight triblock copolymer derived from ε-caprolactone and tetrahydrofuran (CT) on the compatibility and cytotoxicity of immiscible poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) blends. Binary and tertiary PLA/PCL blends were prepared by melt mixing in a twin-screw extruder and their morphological, mechanical and thermal behaviors were investigated by scanning electron microscopy (SEM), tensile and Izod impact test, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). SEM micrographs showed the CT copolymer suppressed the coalescence phenomena and maintained the size of dispersed PCL domains at approximately 0.35µm. Bioresorbable PLA/PCL blends containing 5wt% of CT copolymer exhibited a remarkable increase in ductility and improved toughness at room temperature. Although the CT copolymer increased the interfacial adhesion, the DMA results suggest it also acts as a plasticizer exclusively for the PCL phase. The cell viability evaluated by the XTT assay confirmed PLA/PCL blends compatibilized by CT copolymer exerted no cytotoxic effect.

  9. Electrospun fiber scaffolds of poly (glycerol-dodecanedioate) and its gelatin blended polymers for soft tissue engineering.

    PubMed

    Dai, Xizi; Kathiria, Khadija; Huang, Yen-Chih

    2014-09-01

    For tissue engineering applications, biodegradable scaffolds play a vital role in supporting and guiding the seeded cells to form functional tissues by mimicking the structure and function of native extracellular matrices. Previously, we have developed a biodegradable elastomer poly (glycerol-dodecanedioate) (PGD) with mechanical properties suitable for soft tissue engineering. In the study, we found that the PGD and PGD blended with gelatin (PGD/gelatin) were able to be electrospun into fibrous scaffolds, and the diameters of the fibers could be adjusted by controlling the PGD concentration. When using our newly designed electrospinning collector, fibers could be easily harvested and the size of the fiber mat could be flexibly adjusted. The data of Raman spectra also confirmed the esterfication reaction in PGD polymerization and showed no significant structure change after electrospinning. Biocompatibility testing of the PGD and PGD/gelatin, by using human foreskin fibroblasts, indicated that gelatin could enhance cell adhesion and proliferation. Overall, electrospun fibers made from PGD and PGD/gelatin exhibited several advantages including easy synthesis from renewable raw materials, flexible fabrication by using less toxic solvents like ethanol, and good biocompatibility.

  10. Spatially Resolving Ordered and Disordered Conformers and Photocurrent Generation in Intercalated Conjugated Polymer/Fullerene Blend Solar Cells

    PubMed Central

    2015-01-01

    Resonance Raman spectroscopy was used to identify ordered and disordered conformers of poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT) blended with the electron acceptor [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in bulk heterojunction (BHJ) solar cells where PCBM intercalates into PBTTT side groups. We show that the PBTTT thiophene ring symmetric C=C stretching mode consists of contributions from ordered (ℏωC=C = 1489 cm–1, fwhm ∼ 15 cm–1) and disordered (ℏωC=C = 1500 cm–1, fwhm ∼ 25 cm–1) components and their relative amounts are sensitive to PCBM loading, annealing and excitation energy. The 1500 cm–1 PBTTT component originates from twisted thiophene rings and disordered side groups due to PCBM intercalation in a mixed kinetic phase and thermal annealing promotes ordering of PBTTT chains from the formation of bimolecular PBTTT/PCBM crystals. Density functional theory (DFT) Raman simulations of PBTTT monomers support these assignments. Resonance Raman images of annealed PBTTT/PCBM model solar cells confirm that ordered PBTTT chains are most concentrated in PCBM-rich bimolecular crystals and corresponding intensity modulated photocurrent spectroscopy (IMPS) and imaging measurements show increased nongeminate charge recombination at the boundaries of ordered/disordered regions. PMID:25678742

  11. Control of charge dynamics by blending ZnO nanoparticles with poly(3-hexylthiophene) for efficient hybrid ZnO nanorods/polymer solar cells

    NASA Astrophysics Data System (ADS)

    Ruankham, Pipat; Choopun, Supab; Sagawa, Takashi

    2015-10-01

    Photovoltaic performances of hybrid ZnO nanorods/polymer solar cells have been improved by controlling their charge dynamics through addition of ZnO nanoparticles into poly(3-hexylthiophene) (P3HT) photoactive layer. The inter-rod space of ZnO nanorod substrates is completely filled with the solution-processed ZnO nanoparticles/P3HT blends, forming homogeneous junction among the components. The optimum PCE of 1.020 % has been achieved from the device with 13 vol % ZnO nanoparticles loaded. The enhancement in external quantum efficiency has been also observed, indicating the improved excitons separation at the ZnO/P3HT interface. The information on charge dynamics in the system has been investigated by electrochemical impedance spectroscopy. It has been found that the additional space-charge layer formed at the ZnO nanoparticles-contact electrode interface is a reason behind the improvement of open-circuit voltage. Moreover, the formation of ZnO nanoparticles domain extending across the active layer and the percolation path for charge carriers promotes charge transport by reducing transit time of the carriers, extending charge carrier lifetime and enhancing the charge transfer at the ZnO/P3HT interface. Interestingly, it has been found that charge transport in the devices does not limit the device performances, even for the 400-nm-thick active layer.

  12. Improved performance of polymer solar cells using PBDTT-F-TT:PC71BM blend film as active layer

    NASA Astrophysics Data System (ADS)

    Zang, Yue; Gao, Xiumin; Lu, Xinmiao; Xin, Qing; Lin, Jun; Zhao, Jufeng

    2016-07-01

    A detailed study of high-efficiency polymer solar cells (PSCs) based on a low bandgap polymer PBDTT-F-TT and PC71BM as the bulk heterojunction (BHJ) layer is carried out. By using 1,8-diiodooctane (DIO) as solvent additive to control the morphology of active layer and comparing different device architecture to optimize the optical field distribution, the power conversion efficiency (PCE) of the resulted devices can be reached as high as 9.34%. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of DIO and device geometry on photovoltaic performance. It was found that the addition of DIO can significantly improve the nanoscale morphology and increased electron mobility in the BHJ layer. The inverted device architecture was chosen because the results from optical modeling shows that it offers better optical field distribution and exciton generation profile. Based on these results, a low-temperature processed ZnO was finally introduced as an electron transport layer to facility the fabrication on flexible substrates and showed comparable performance with the device based on conventional ZnO interlayer prepared by sol-gel process.

  13. Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

    PubMed Central

    McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

    2010-01-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

  14. Experimental studies of siloxane polymers and their elastomeric networks

    SciTech Connect

    Kuo, Chung Mien

    1992-12-31

    Siloxane polymers have been investigated systematically for the purpose of a greater understanding of the structure-property relationships in terms of their synthesis, polymer blends and rubber elasticity of their crosslinked networks. This study includes a variety of topological structures: linear, cyclic and crosslinked networks of poly(dimethylsiloxane) (PDMS) and poly(dimethylco-methylphenylsiloxane) copolymers. Siloxane polymers with a narrow molecular weight distribution were prepared by a series of well-characterized organometallic polymerizations. The reaction conditions and mechanisms for preparing polyorganosiloxane chains and networks using organotin catalyst and promoters were discussed. Experimental evidence shows that formamide was one of the best additives to improve the reactivity of the tin dicarboxylate catalyst, which seems to suggest that the nucleophilic function of the additive was on the Sn atom. Since the PDMS and PMPS are immiscible under most conditions, the miscibility and phase behavior of siloxane blends were studied by a static light scattering t technique. THe influence of molar mass, the topological effect of cyclic and linear structures, the end-group effect, and the configurational isomerism effect on miscibility were examined. Silicon networks of PDMS, PMPS and their copolymers were prepared at room temperature using the crosslinked siloxane homopolymer and copolymer networks at equilibrium swelling in organic solvents and in liquid siloxane oligomers were investigated as function of crosslinking density and composition variation. The resulting interaction parameters for PDMS and PMPS from the swollen siloxane networks in siloxane oligomers individually were compared with those from measurements of the corresponding blend systems. Moreover, the stress-strain behavior of the siloxane polymer networks undergoing uniaxial deformation were evaluated by a stress-strain experiment.

  15. Valence band structure of PDMS surface and a blend with MWCNTs: A UPS and MIES study of an insulating polymer

    NASA Astrophysics Data System (ADS)

    Schmerl, Natalya M.; Khodakov, Dmitriy A.; Stapleton, Andrew J.; Ellis, Amanda V.; Andersson, Gunther G.

    2015-10-01

    The use of polydimethylsiloxane (PDMS) is increasing with new technologies working toward compact, flexible and transparent devices for use in medical and microfluidic systems. Electronic characterization of PDMS and other insulating materials is difficult due to charging, yet necessary for many applications where the interfacial structure is vital to device function or further modification. The outermost layer in particular is of importance as this is the area where chemical reactions such as surface functionalization will occur. Here, we investigate the valence band structure of the outermost layer and near surface area of PDMS through the use of metastable induced photoelectron spectroscopy (MIES) paired with ultraviolet photoelectron spectroscopy (UPS). The chemical composition of the samples under investigation were measured via X-ray photoelectron spectroscopy (XPS), and the vertical distribution of the polymer was shown with neutral impact collision ion scattering spectroscopy (NICISS). Three separate methods for charge compensation are used for the samples, and their effectiveness is compared.

  16. A new method of fabricating a blend scaffold using an indirect three-dimensional printing technique.

    PubMed

    Jung, Jin Woo; Lee, Hyungseok; Hong, Jung Min; Park, Jeong Hun; Shim, Jung Hee; Choi, Tae Hyun; Cho, Dong-Woo

    2015-11-03

    Due to its simplicity and effectiveness, the physical blending of polymers is considered to be a practical strategy for developing a versatile scaffold having desirable mechanical and biochemical properties. In the present work, an indirect three-dimensional (i3D) printing technique was proposed to fabricate a 3D free-form scaffold using a blend of immiscible materials, such as polycaprolactone (PCL) and gelatin. The i3D printing technique includes 3D printing of a mold and a sacrificial molding process. PCL/chloroform and gelatin/water were physically mixed to prepare the blend solution, which was subsequently injected into the cavity of a 3D printed mold. After solvent removal and gelatin cross-linking, the mold was dissolved to obtain a PCL-gelatin (PG) scaffold, with a specific 3D structure. Scanning electron microscopy and Fourier transform infrared spectroscopy analysis indicated that PCL masses and gelatin fibers in the PG scaffold homogenously coexisted without chemical bonding. Compression tests confirmed that gelatin incorporation into the PCL enhanced its mechanical flexibility and softness, to the point of being suitable for soft-tissue engineering, as opposed to pure PCL. Human adipose-derived stem cells, cultured on a PG scaffold, exhibited enhanced in vitro chondrogenic differentiation and tissue formation, compared with those on a PCL scaffold. The i3D printing technique can be used to blend a variety of materials, facilitating 3D scaffold fabrication for specific tissue regeneration. Furthermore, this convenient and versatile technique may lead to wider application of 3D printing in tissue engineering.

  17. The UV and Laser Aging for PMMA/BDK/Azo-dye Polymer Blend Cured by UV Light Beams

    NASA Astrophysics Data System (ADS)

    Ahmad, A. A.; Omari, A. M.

    2015-10-01

    A polymeric-based solution blend composed of Azo-dye methyl red (MR) doped with polymethelmethacrelate (PMMA) solution, in addition, to the BenzylDimethylKetal (BDK) photoinitiator was made with optimum molar ratios and deposited on glass substrate by spin coating technique. The samples were then exposed to UV light beams in order to assist the layers polymerization by the proper exposure process. The photo chemical reaction occurred during the UV light polymerization process induces photo refractive changes which were presented as a function of wavelength or photon energy. Two main strong absorption peaks were observed in the films at around 330 nm (3.75 eV) and 500 nm (2.48 eV) for different curing time periods. This phenomenon enhances the films usage for optical data storage media at these two wavelengths. Since the deposited films were then useful as based layers for Read/Write optical data storage media, they were then tested by UV or laser Read/Write beams independently. The optical properties of the films were investigated while exposed to each beam. Finally, their optical properties were investigated as a function of aging time in order to relate the temporary and/or permanent light-exposure effect on the films compared to their optical properties before the light exposure. The films show a low absorbance at 630 nm (1.97 eV) and high absorbance at 480 nm (2.58 eV). This fact makes it possible to record holographic gratings in the polymeric film upon light exposure. In all cases the optical properties were evaluated by using the very sensitive, non destructive surface testing spectroscopic ellipsometry technique. The films were characterized in the spectral range of 300 to 1000 nm using Lorentz oscillator model with one oscillator centred at 4.15 eV. This study has been supported by the SEM and EDAX results to investigate the effect of the UV and visible beams on their optical properties. The results of this research determined the proper conditions for

  18. Light-induced electron paramagnetic resonance evidence of charge transfer in electrospun fibers containing conjugated polymer/fullerene and conjugated polymer/fullerene/carbon nanotube blends

    NASA Astrophysics Data System (ADS)

    Shames, Alexander I.; Bounioux, Céline; Katz, Eugene A.; Yerushalmi-Rozen, Rachel; Zussman, Eyal

    2012-03-01

    Electrospun sub-micron fibers containing conjugated polymer (poly(3-hexylthiophene), P3HT) with a fullerene derivative, phenyl-C61-butyric acid methylester (PCBM) or a mixture of PCBM and single-walled carbon nanotubes (SWCNTs) were studied by light-induced electron paramagnetic resonance spectroscopy. The results provide experimental evidence of electron transfer between PCBM and P3HT components in both fiber systems and suggest that the presence of a dispersing block-copolymer, which acts via physical adsorption onto the PCBM and SWCNT moieties, does not prevent electron transfer at the P3HT-PCBM interface. These findings suggest a research perspective towards utilization of fibers of functional nanocomposites in fiber-based organic optoelectronic and photovoltaic devices. The latter can be developed in the textile-type large area photovoltaics or individual fiber-based solar cells that will broaden energy applications from macro-power tools to micro-nanoscale power conversion devices and smart textiles.

  19. Light-induced electron paramagnetic resonance evidence of charge transfer in electrospun fibers containing conjugated polymer/fullerene and conjugated polymer/fullerene/carbon nanotube blends

    SciTech Connect

    Shames, Alexander I.; Bounioux, Celine; Katz, Eugene A.; Yerushalmi-Rozen, Rachel; Zussman, Eyal

    2012-03-12

    Electrospun sub-micron fibers containing conjugated polymer (poly(3-hexylthiophene), P3HT) with a fullerene derivative, phenyl-C61-butyric acid methylester (PCBM) or a mixture of PCBM and single-walled carbon nanotubes (SWCNTs) were studied by light-induced electron paramagnetic resonance spectroscopy. The results provide experimental evidence of electron transfer between PCBM and P3HT components in both fiber systems and suggest that the presence of a dispersing block-copolymer, which acts via physical adsorption onto the PCBM and SWCNT moieties, does not prevent electron transfer at the P3HT-PCBM interface. These findings suggest a research perspective towards utilization of fibers of functional nanocomposites in fiber-based organic optoelectronic and photovoltaic devices. The latter can be developed in the textile-type large area photovoltaics or individual fiber-based solar cells that will broaden energy applications from macro-power tools to micro-nanoscale power conversion devices and smart textiles.

  20. Production and characterization of thermoplastic cassava starch, functionalized poly(lactic acid), and their reactive compatibilized blends

    NASA Astrophysics Data System (ADS)

    Detyothin, Sukeewan

    Cassava starch was blended with glycerol using a co-rotating twin-screw extruder (TSE). Thermoplastic cassava starch (TPCS) at a ratio of 70/30 by weight of cassava/glycerol was selected and further blended with other polymers. TPCS sheets made from compression molding had low tensile strength (0.45 +/- 0.05 MPa) and Young's modulus (1.24 +/- 0.58 MPa), but moderate elongation at break (83.0 +/- 0.18.6%), medium level of oxygen permeability, and high water vapor permeability with a very high rate of water absorption. TPCS was blended with poly(lactic acid) (PLA) at various ratios by using a TSE. The blend resins exhibited good properties such as increased thermal stability (Tmax) and crystallinity of PLA, and improved water sensitivity and processability of TPCS. PLA and TPCS exhibited a high interfacial tension between the two phases of 7.9 mJ·m -2, indicating the formation of an incompatible, immiscible blend. SEM micrographs showed a non-homogeneous distribution of TPCS droplets in the PLA continuous phase. TEM micrographs of the blend films made by cast-film extrusion showed coalescence of the TPCS droplets in the PLA continuous phase of the blend, indicating that the compatibility between the polymer pair needs to be improved. A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox or L101) contents, and TSE screw speed on the degree of grafted MA and number average molecular weight (Mn) of functionalized PLA (PLA-g-MA), a reactive compatibilizer. PLA-g- MA made by reactive extrusion had an array of colors depending on the content of L101 and MA used. New FTIR peaks suggested that MA was grafted onto the PLA backbone and oligomeric MA may occur. Increasing L101 increased the degree of grafting and decreased Mn, but the Mn of the PLA-g-MA's produced with a high amount of L101 was stable during storage. MA exhibited an optimum concentration for maximizing the

  1. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  2. Time-domain shape of electron spin echo signal of spin-correlated radical pairs in polymer/fullerene blends.

    PubMed

    Popov, Alexander A; Lukina, Ekaterina A; Rapatskiy, Leonid; Kulik, Leonid V

    2017-03-01

    Temporal shape of electron spin echo (ESE) signal of photoinduced spin-correlated radical pairs (SCRP) in composite of conductive polymer P3HT and substituted fullerene PCBM is studied in details. ESE signals of radical pairs (RP) P3HT(+)/PCBM(-) are calculated in realistic model, taking into account finite microwave pulse length. Inhomogeneous broadening of resonant lines and interradical distance distribution are included. Experimentally observed ESE time-domain shape was found to contradict predictions of conventional SCRP theory, which would be valid in the case of very fast electron transfer. Thus, instantaneous formation of singlet SCRP is not the case for P3HT(+)/PCBM(-) pair, and spin system has enough time to evolve coherently during sequential electron transfer. While it is impossible to reproduce experimental data within simple singlet SCRP model, assumption of presence of additional - with respect to what is predicted by singlet SCRP theory - AE (absorption/emission) spin polarization gives convincing accordance with the experiment. Density matrix of RP P3HT(+)/PCBM(-) is a superposition of two contributions, namely the parts reflecting (i) antiphase polarization of original singlet-born SCRP and (ii) additional AE-polarization which is generated during initial stage of charge separation. AE-polarization affects experimental ESEEM (electron spin echo envelope modulation) traces, as well as ESE shape, making impossible their interpretation via simple singlet SCRP model. However, this effect can be eliminated by averaging of ESEEM traces over EPR spectral positions. Finally, choosing the optimal gate for ESE time-domain integration and proper microwave detection phase tuning are considered.

  3. Time-domain shape of electron spin echo signal of spin-correlated radical pairs in polymer/fullerene blends

    NASA Astrophysics Data System (ADS)

    Popov, Alexander A.; Lukina, Ekaterina A.; Rapatskiy, Leonid; Kulik, Leonid V.

    2017-03-01

    Temporal shape of electron spin echo (ESE) signal of photoinduced spin-correlated radical pairs (SCRP) in composite of conductive polymer P3HT and substituted fullerene PCBM is studied in details. ESE signals of radical pairs (RP) P3HT+/PCBM- are calculated in realistic model, taking into account finite microwave pulse length. Inhomogeneous broadening of resonant lines and interradical distance distribution are included. Experimentally observed ESE time-domain shape was found to contradict predictions of conventional SCRP theory, which would be valid in the case of very fast electron transfer. Thus, instantaneous formation of singlet SCRP is not the case for P3HT+/PCBM- pair, and spin system has enough time to evolve coherently during sequential electron transfer. While it is impossible to reproduce experimental data within simple singlet SCRP model, assumption of presence of additional - with respect to what is predicted by singlet SCRP theory - AE (absorption/emission) spin polarization gives convincing accordance with the experiment. Density matrix of RP P3HT+/PCBM- is a superposition of two contributions, namely the parts reflecting (i) antiphase polarization of original singlet-born SCRP and (ii) additional AE-polarization which is generated during initial stage of charge separation. AE-polarization affects experimental ESEEM (electron spin echo envelope modulation) traces, as well as ESE shape, making impossible their interpretation via simple singlet SCRP model. However, this effect can be eliminated by averaging of ESEEM traces over EPR spectral positions. Finally, choosing the optimal gate for ESE time-domain integration and proper microwave detection phase tuning are considered.

  4. Bimodal porous TiO2 structures templated by graft copolymer/homopolymer blend for dye-sensitized solar cells with polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Kim, Jin Kyu; Lee, Chang Soo; Lee, Sang-Yup; Cho, Hyung Hee; Kim, Jong Hak

    2016-12-01

    Bimodal porous TiO2 (BP-TiO2) with large surface area, high porosity, good interconnectivity, and excellent light-scattering ability are synthesized via a facile one-step method using a self-assembled blend template consisting of an amphiphilic poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer and a hydrophobic poly(vinyl chloride) (PVC) homopolymer. The hydrophilically surface-modified TiO2 nanoparticles selectively interact with the hydrophilic POEM chains, while the addition of the PVC homopolymer increases the hydrophobic domain size, resulting in the formation of dual pores (i.e., macropores and mesopores). The sizes and numbers of macropores can easily be controlled by changing the molecular weight and amount of the PVC homopolymer. The polymer electrolyte dye-sensitized solar cells (DSSCs) fabricated with BP-TiO2 photoanodes exhibited energy conversion efficiencies of up to 7.6% at 100 mW cm-2, which is much higher than those of mesoporous TiO2 (5.8%) with PVC-g-POEM only and conventional nanocrystalline TiO2 (4.9%) with commercial Dyesol paste. The enhanced energy conversion efficiencies mostly resulted from the light-scattering effects of the macropores, which increased the light-harvesting efficiencies. The improved light-harvesting and photovoltaic performances of the DSSCs were characterized by UV-vis spectroscopy, incident photon-to-current conversion efficiency analysis, electrochemical impedance spectroscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltage spectroscopy.

  5. Tuning the dielectric properties of polystyrene/poly(vinylidene fluoride) blends by selectively localizing carbon black nanoparticles.

    PubMed

    Zhao, Xiaodong; Zhao, Jun; Cao, Jian-Ping; Wang, Xiaoyan; Chen, Min; Dang, Zhi-Min

    2013-02-28

    In this work, the dielectric properties of immiscible polystyrene (PS)/poly(vinylidene fluoride) (PVDF) blends are tuned by selectively localizing carbon black (CB) nanoparticles in different phases. The PS/PVDF blends have a wide window of cocontinuity (ca. 30-80 vol % in terms of the volume fraction of PS component (v(PS))). The selective localization of CB nanoparticles is achieved by using the masterbatch process during melt mixing. For the volume ratio PS/PVDF 1/1 and the volume fraction of CB nanoparticles (v(CB)) below but close to the percolation threshold (v(c)(CB)), the selective localization of CB nanoparticles in PVDF phase produces higher dielectric constant (ε) than that in PS phase, whereas the ε of the ternary mixtures without selective localization of fillers is in the middle. For the volume ratios PS/PVDF 1/2 and 2/1, the selective location of CB nanoparticles in different phases can be used to easily tune the system from conductive to insulating or inverse, which might have potential applications in industry. The fillers are found to be "fixed" in the masterbatch of PS or PVDF component and there is no migration of the fillers to another phase occurring during the further mixing process for the mixing time up to 30 min. Furthermore, the addition of CB nanoparticles to the polymer matrix is found to induce the brittle-ductile transition in the system and increase the compatibility between the immiscible PS and PVDF components, which should benefit the mechanical properties.

  6. Blended Learning

    ERIC Educational Resources Information Center

    Imbriale, Ryan

    2013-01-01

    Teachers always have been and always will be the essential element in the classroom. They can create magic inside four walls, but they have never been able to create learning environments outside the classroom like they can today, thanks to blended learning. Blended learning allows students and teachers to break free of the isolation of the…

  7. Blended Learning

    ERIC Educational Resources Information Center

    Tucker, Catlin; Umphrey, Jan

    2013-01-01

    Catlin Tucker, author of "Blended Learning in Grades 4-12," is an English language arts teacher at Windsor High School in Sonoma County, CA. In this conversation with "Principal Leadership," she defines blended learning as a formal education program in which a student is engaged in active learning in part online where they…

  8. Potential of a newly developed high-speed near-infrared (NIR) camera (Compovision) in polymer industrial analyses: monitoring crystallinity and crystal evolution of polylactic acid (PLA) and concentration of PLA in PLA/Poly-(R)-3-hydroxybutyrate (PHB) blends.

    PubMed

    Ishikawa, Daitaro; Nishii, Takashi; Mizuno, Fumiaki; Sato, Harumi; Kazarian, Sergei G; Ozaki, Yukihiro

    2013-12-01

    This study was carried out to evaluate a new high-speed hyperspectral near-infrared (NIR) camera named Compovision. Quantitative analyses of the crystallinity and crystal evolution of biodegradable polymer, polylactic acid (PLA), and its concentration in PLA/poly-(R)-3-hydroxybutyrate (PHB) blends were investigated using near-infrared (NIR) imaging. This NIR camera can measure two-dimensional NIR spectral data in the 1000-2350 nm region obtaining images with wide field of view of 150 × 250 mm(2) (approximately 100  000 pixels) at high speeds (in less than 5 s). PLA with differing crystallinities between 0 and 50% blended samples with PHB in ratios of 80/20, 60/40, 40/60, 20/80, and pure films of 100% PLA and PHB were prepared. Compovision was used to collect respective NIR spectra in the 1000-2350 nm region and investigate the crystallinity of PLA and its concentration in the blends. The partial least squares (PLS) regression models for the crystallinity of PLA were developed using absorbance, second derivative, and standard normal variate (SNV) spectra from the most informative region of the spectra, between 1600 and 2000 nm. The predicted results of PLS models achieved using the absorbance and second derivative spectra were fairly good with a root mean square error (RMSE) of less than 6.1% and a determination of coefficient (R(2)) of more than 0.88 for PLS factor 1. The results obtained using the SNV spectra yielded the best prediction with the smallest RMSE of 2.93% and the highest R(2) of 0.976. Moreover, PLS models developed for estimating the concentration of PLA in the blend polymers using SNV spectra gave good predicted results where the RMSE was 4.94% and R(2) was 0.98. The SNV-based models provided the best-predicted results, since it can reduce the effects of the spectral changes induced by the inhomogeneity and the thickness of the samples. Wide area crystal evolution of PLA on a plate where a temperature slope of 70-105 °C had occurred was also

  9. Structure, ion transport, and relaxation dynamics of polyethylene oxide/poly (vinylidene fluoride co-hexafluoropropylene)—lithium bis(trifluoromethane sulfonyl) imide blend polymer electrolyte embedded with ionic liquid

    NASA Astrophysics Data System (ADS)

    Das, S.; Ghosh, A.

    2016-03-01

    We have studied structure, ion transport, and relaxation dynamics in polyethylene oxide/poly (vinylidene fluoride-hexafluoropropylene)-lithium bis(trifluoromethane)sulfonimide blend polymer electrolytes embedded with 1-propyl-3-methyleimidazoliuum bis(trifluromethyle-sulfonyl)imide ionic liquid. Structural property and ion-polymer interaction of polymer electrolytes have been studied using X-ray diffraction and Raman spectroscopy. The addition of ionic liquid decreases glass transition temperature and reduces crystalline phase in the polymer matrix. It is also observed that surface becomes smooth with increase of ionic liquid content. The temperature dependence of the Li ion conductivity follows Vogel-Tammann-Fulcher type behaviour when a sufficient amount of ionic liquid is added to polymer matrix. The electric modulus has been studied using Havriliak-Negami function for the understanding of ion dynamics. The modulus data have been analyzed using non-exponential Kohlrausch-Williams-Watts function. It is observed that the non-exponential parameter β is quite lower than unity, suggesting existence of a non-exponential relaxation. The temperature dependence of the relaxation time also follows Vogel-Tammann-Fulcher relation for compositions with higher ionic liquid content.

  10. Blends of chitin and chitosan with polyamide 66

    SciTech Connect

    Gonzalez, V.; Guerrero, C.

    1996-12-31

    For several years, intense interest has been focused on polymer blends in which both components are synthetic polymers. However, few studies have been made on blends in which one component is chitin (QA), or chitosan (QN), the most abundant natural polymers after cellulose. Its chemical structure, based in partially acetilated {beta}-aminosaccharide units, permits the formation of natural blends with proteins and inorganic salts were the intermolecular hydrogen bonds play an important role. The choice of a partner for these natural polymers was made expecting strong interaction between the two polymers. For this reason, on this work, polyamide 66 (P66), has been chosen.

  11. Local friction in polyolefin blends

    NASA Astrophysics Data System (ADS)

    Luettmer-Strathmann, Jutta

    2005-07-01

    Processes on different length scales affect the dynamics of chain molecules. The friction experienced by a short chain segment depends on both small-scale chain properties and on the local environment of the segment. As a consequence, the (monomeric) friction coefficients of the two components of a binary polymer blend will, in general, differ from each other and from the friction coefficients of the corresponding melts. In this work, we investigate local friction in polyolefin blends with the aid of a small-scale simulation approach. The polymer chains, in united atom representation, are assumed to occupy the sites of a partially filled simple cubic lattice. The simulation focuses on short chain sections with straight backbones and enumerates all possible binary contacts and relative movements of such sections. By evaluating the exact enumeration results in conjunction with equations of state for the blends, we are able to make predictions about the variation of the friction coefficients with local chain architecture and thermodynamic state (temperature, pressure, and composition). We calculate relative values of friction coefficients at temperatures well above the glass transition for blends of PEP, an alternating copolymer of polyethylene and polypropylene, with polyethylene and polyisobutylene and for blends of polyethylene and atactic polypropylene. We also investigate a blend of PEP with head-to-head polypropylene and compare our results with experimental data.

  12. Experiments on liquid immiscibility along tholeiitic liquid lines of descent

    NASA Astrophysics Data System (ADS)

    Charlier, Bernard; Grove, Timothy L.

    2012-07-01

    Crystallization experiments have been conducted on compositions along tholeiitic liquid lines of descent to define the compositional space for the development of silicate liquid immiscibility. Starting materials have 46-56 wt% SiO2, 11.7-17.7 wt% FeOtot, and Mg-number between 0.29 and 0.36. These melts fall on the basaltic trends relevant for Mull, Iceland, Snake River Plain lavas and for the Sept Iles layered intrusion, where large-scale liquid immiscibility has been recognized. At one atmosphere under anhydrous conditions, immiscibility develops below 1,000-1,020°C in all of these compositionally diverse lavas. Extreme iron enrichment is not necessary; immiscibility also develops during iron depletion and silica enrichment. Variations in melt composition control the development of silicate liquid immiscibility along the tholeiitic trend. Elevation of Na2O + K2O + P2O5 + TiO2 promotes the development of two immiscible liquids. Increasing melt CaO and Al2O3 stabilizes a single-liquid field. New data and published phase equilibria show that anhydrous, low-pressure fractional crystallization is the most favorable condition for unmixing during differentiation. Pressure inhibits immiscibility because it expands the stability field of high-Ca clinopyroxene, which reduces the proportion of plagioclase in the crystallizing assemblage, thus enhancing early iron depletion. Magma mixing between primitive basalt and Fe-Ti-P-rich ferrobasalts can serve to elevate phosphorous and alkali contents and thereby promote unmixing. Water might decrease the temperature and size of the two-liquid field, potentially shifting the binodal (solvus) below the liquidus, leading the system to evolve as a single-melt phase.

  13. Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

    DOEpatents

    Spauschus, Hans O.; Starr, Thomas L.

    1999-01-01

    A method of separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed.

  14. Effect of wettability on adverse mobility immiscible floods

    SciTech Connect

    Vives, M.T.; Chang, Y.C.; Mohanty, K.K.

    1995-12-31

    Many immiscible displacements in reservoirs occur at adverse mobility. Effect of wettability on these displacements is not well understood and often ignored in reservoir simulation. Recent macroscopic theories of viscous fingering treat adverse immiscible flows similar to miscible flows, the mixing in the fingered region being controlled by a Todd-Longstaff-type functional form. The wettability of the medium is taken into account only through the use of appropriate relative permeabilities. The goal of this paper is to understand the macroscopic bypassing in adverse mobility immiscible floods. Immiscible displacements are conducted in a quarter 5-spot model in both drainage and imbibition modes at similar effective mobility ratios and viscous-to-gravity numbers. The level of bypassing and gravity override is visualized and measured. Tertiary water-alternating-gas (WAG) displacements are also conducted at various WAG ratios and viscosity ratios. Fractional flow analysis and numerical simulation are used to understand these displacements. Experiments show that macroscopic viscous fingering is present in adverse viscosity immiscible displacements where no saturation shock is expected from 1-D fractional flow theory. Bypassing due to both fingering and gravity override is higher in the drainage mode than in the imbibition mode, with other key parameters being the same. Optimum WAG ratio in water-wet rock is a function of oil/solvent viscosity ratio. The macroscopic flow theory needs to include capillarity and viscous fingering to match these experimental findings.

  15. Enzymatic degradation of polycaprolactone-gelatin blend

    NASA Astrophysics Data System (ADS)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-04-01

    Blends of polycaprolactone (PCL), a synthetic polymer and gelatin, natural polymer offer a optimal combination of strength, water wettability and cytocompatibility for use as a resorbable biomaterial. The enzymatic degradation of PCL, gelatin and PCL-gelatin blended films was studied in the presence of lipase (Novozym 435, immobilized) and lysozyme. Novozym 435 degraded the PCL films whereas lysozyme degraded the gelatin. Though Novozym 435 and lysozyme individually could degrade PCL-gelatin blended films, the combination of these enzymes showed the highest degradation of these blended films. Moreover, the enzymatic degradation was much faster when fresh enzymes were added at regular intervals. The changes in physico-chemical properties of polymer films due to degradation were studied by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. These results have important implications for designing resorbable biomedical implants.

  16. Liquid immiscibility in model bilayer lipid membranes

    NASA Astrophysics Data System (ADS)

    Veatch, Sarah L.

    There is growing evidence that cell plasma membranes are laterally organized into "raft" regions in which particular lipids and proteins are concentrated. These domains have sub-micron dimensions and have been implicated in vital cell functions. Similar liquid domains are observed in model bilayer membrane mixtures that mimick cellular lipid compositions. In model membranes, domains can be large (microns) and can readily form in the absence of proteins. This thesis presents studies of liquid immiscibility in model membrane systems using two experimental methods. By fluorescence microscopy, this thesis documents that miscibility transitions occur in a wide variety of ternary lipid mixtures containing high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol. I have constructed detailed miscibility phase diagrams for three separate ternary lipid mixtures (DOPC/DPPC/Chol, DOPC/PSM/Chol, and POPC/PSM/Chol). Phase separation is also observed in membranes of lipids extracted from human erythrocytes. NMR experiments probe lipid order and verify the coexistence of a saturated lipid and cholesterol rich liquid ordered (Lo) phase with a more disordered, unsaturated lipid rich liquid crystalline (Lalpha) phase at low temperatures. These experiments also find multiple thermodynamic transitions and lipid organization on different length-scales. This complexity is revealed because fluorescence microscopy and NMR probe lipid order at different length-scales (>1mum vs. ˜100nm). NMR detects small domains (˜80nm) at temperatures just below the miscibility transition, even though micron-scale domains are observed by fluorescent microscopy. NMR does detect large-scale ("100nm) demixing, but at a lower temperature. In addition, it has long been known that >10nm length-scale structure is present in many lipid mixtures containing cholesterol and at least one additional lipid species, though it is shown here that only a subset of

  17. Containerless low gravity processing of glass forming and immiscible alloys

    NASA Technical Reports Server (NTRS)

    Andrews, J. Barry; Briggs, Craig; Robinson, M. B.

    1990-01-01

    Under normal one-g conditions immiscible alloys segregate extensively during solidification due to sedimentation of the more dense of the immiscible liquid phases. Immiscible (hypermonotectic) gold-rhodium alloys were processed in the 100 meter drop tube under low gravity, containerless conditions to determine the feasibility of producing dispersed structures. Three alloy compositions were utilized. Alloys containing 10 percent by volume of the gold-rich hypermonotectic phase exhibited a tendency for the gold-rich liquid to wet the outer surface of the samples. This wetting tendency led to extensive segregation in several cases. Alloys containing 80 and 90 percent by volume of the gold-rich phase possessed completely different microstructures from the 10 percent samples when processed under low-g, containerless conditions. Several samples exhibited microstructures consisting of well dispersed 2 to 3 microns diameter rhodium-rich spheres in a gold-rich matrix.

  18. Evaluation of physicochemical and biological properties of chitosan/poly (vinyl alcohol) polymer blend membranes and their correlation for Vero cell growth.

    PubMed

    Sharma, Parul; Mathur, Garima; Dhakate, Sanjay R; Chand, Subhash; Goswami, Navendu; Sharma, Sanjeev K; Mathur, Ashwani

    2016-02-10

    The blend membranes with varying weight ratios of chitosan/poly (vinyl alcohol) (CS/PVA) (1:0, 1:1, 1:2.5, 1.5:1, 1.5: 2.5) were prepared using solvent casting method and were evaluated for their potential application in single-use membrane bioreactors (MBRs). The physicochemical properties of the prepared membranes were investigated for chemical interactions (FTIR), surface morphology (SEM), water uptake, protein sorption (qe), ammonia sorption and growth kinetics of Vero cells. CS/PVA blend membrane having weight ratio of 1.5:1 had shown enhanced membrane flexibility, reduced water uptake, less protein sorption and no ammonium sorption compared to CS membrane. This blend membrane also showed comparatively enhanced higher specific growth rate (0.82/day) of Vero cells. Improved physicochemical properties and growth kinetics obtrude CS/PVA (1.5:1) as a potential surface for adhesion and proliferation with possible application in single use membrane bioreactors. Additionally, new insight explaining correlation between water holding (%) of CS/PVA (1.5:1) blend membrane and doubling time (td) of Vero cells is proposed.

  19. Controlled release of acidic drugs in compendial and physiological hydrogen carbonate buffer from polymer blend-coated oral solid dosage forms.

    PubMed

    Wulff, R; Rappen, G-M; Koziolek, M; Garbacz, G; Leopold, C S

    2015-09-18

    The objective of this study was to investigate the suitability of "Eudragit® RL/Eudragit® L55" (RL/L55) blend coatings for a pH-independent release of acidic drugs. A coating for ketoprofen and naproxen mini tablets was developed showing constant drug release rate under pharmacopeial two-stage test conditions for at least 300 min. To simulate drug release from the mini tablets coated with RL/L55 blends in the gastrointestinal (GI) tract, drug release profiles in Hanks buffer pH 6.8 were recorded and compared with drug release profiles in compendial media. RL/L55 blend coatings showed increased drug permeability in Hanks buffer pH 6.8 compared to phosphate buffer pH 6.8 due to its higher ion concentration. However, drug release rates of acidic drugs were lower in Hanks buffer pH 6.8 because of the lower buffer capacity resulting in reduced drug solubility. Further dissolution tests were performed in Hanks buffer using pH sequences simulating the physiological pH conditions in the GI tract. Drug release from mini tablets coated with an RL/L55 blend (8:1) was insensitive to pH changes of the medium within the pH range of 5.8-7.5. It was concluded that coatings of RL/L55 blends show a high potential for application in coated oral drug delivery systems with a special focus on pH-independent release of acidic drugs.

  20. Miscibility study of hexanoyl chitosan in blend with epoxidized natural rubber by viscometric analysis

    NASA Astrophysics Data System (ADS)

    Jamal, Asheila; Chan, C. H.; Muhammad, F. H.; Winie, Tan

    2015-08-01

    Miscibility of blends of hexanoyl chitosan and epoxidized natural rubber with 25 mol% epoxidation level (ENR25) was investigated by dilute solution viscometry (DSV). Experimental results obey the Huggins' equation in the concentration range under investigation. Intrinsic viscosities are found to vary linearly with blend composition. The difference between experimental and ideal Huggins coefficients, κ =K12-√{K1ṡK2 } is proposed to evaluate the miscibility behavior of the blends. Negative deviations from the ideal behavior indicated immiscibility between hexanoyl chitosan and ENR25.

  1. Ultrathin-skinned asymmetric membranes by immiscible solvents treatment

    DOEpatents

    Friesen, D.T.; Babcock, W.C.

    1989-11-28

    Improved semipermeable asymmetric fluid separation membranes useful in gas, vapor and liquid separations are disclosed. The membranes are prepared by substantially filling the pores of asymmetric cellulosic semipermeable membranes having a finely porous layer on one side thereof with a water immiscible organic liquid, followed by contacting the finely porous layer with water.

  2. Measurement of interfacial tension of immiscible liquid pairs in microgravity

    NASA Technical Reports Server (NTRS)

    Weinberg, Michael C.; Neilson, George F.; Baertlein, Carl; Subramanian, R. Shankar; Trinh, Eugene H.

    1994-01-01

    A discussion is given of a containerless microgravity experiment aimed at measuring the interfacial tension of immiscible liquid pairs using a compound drop rotation method. The reasons for the failure to execute such experiments in microgravity are described. Also, the results of post-flight analyses used to confirm our arguments are presented.

  3. Lattice Boltzmann equation method for multiple immiscible continuum fluids.

    PubMed

    Spencer, T J; Halliday, I; Care, C M

    2010-12-01

    This paper generalizes the two-component algorithm of Sec. , extending it, in Sec. , to describe N>2 mutually immiscible fluids in the isothermal continuum regime. Each fluid has an independent interfacial tension. While retaining all its computational advantages, we remove entirely the empiricism associated with contact behavior in our previous multiple immiscible fluid models [M. M. Dupin, Phys. Rev. E 73, 055701(R) (2006); Med. Eng. Phys. 28, 13 (2006)] while solidifying the physical foundations. Moreover, the model relies upon a fluid-fluid segregation which is simpler, computationally faster, more free of artifacts (i.e., the interfacial microcurrent), and upon an interface-inducing force distribution which is analytic. The method is completely symmetric between any numbers of immiscible fluids and stable over a wide range of directly input interfacial tension. We present data on the steady-state properties of multiple interface model, which are in good agreement with theory [R. E. Johnson and S. S. Sadhal, Annu. Rev. Fluid Mech. 17, 289 (1985)], specifically on the shapes of multidrop systems. Section is an analysis of the kinetic and continuum-scale descriptions of the underlying two-component lattice Boltzmann model for immiscible fluids, extendable to more than two immiscible fluids. This extension requires (i) the use of a more local kinetic equation perturbation which is (ii) free from a reliance on measured interfacial curvature. It should be noted that viewed simply as a two-component method, the continuum algorithm is inferior to our previous methods, reported by Lishchuk [Phys. Rev. E 67, 036701 (2003)] and Halliday [Phys. Rev. E 76, 026708 (2007)]. Greater stability and parameter range is achieved in multiple drop simulations by using the forced multi-relaxation-time lattice Boltzmann method developed, along with (for completeness) a forced exactly incompressible Bhatnagar-Gross-Krook lattice Boltzmann model, in the Appendix. These appended schemes

  4. Effects of photointensity gradient on directional crystal growth in blends of crystalline polymer and photoreactive monomer undergoing photopolymerization-induced phase transformation

    SciTech Connect

    Rathi, Pankaj; Park, Soo Jeoung; Kyu, Thein

    2009-05-07

    Effects of light intensity gradient on development of intricate hierarchical morphology of semicrystalline polyethylene oxide (PEO) and photoreactive diacrylate (DA) blends undergoing photopolymerization-induced crystallization have been demonstrated experimentally and theoretically. The melting temperature of PEO was found to decline upon addition of DA monomer. A solid-liquid phase diagram has been established by self-consistently solving the combined phase field free energy of crystal solidification and Flory-Huggins (FH) free energy of liquid-liquid demixing. Dynamic calculations were performed using time-dependent Ginzburg-Landau (model C) equations by incorporating the combined phase field and FH free energy densities coupled with the photopolymerization kinetics. The spatiotemporal development of gradient morphology was computed under various intensity gradient profiles including linear, cylindrical, and Gaussian profiles. The observed seaweed or dense lamellar branching morphology of the PEO/DA blend is strikingly similar to the directionally grown interface structures observed in metals driven by external thermal gradients.

  5. Dually actuated triple shape memory polymers of cross-linked polycyclooctene-carbon nanotube/polyethylene nanocomposites.

    PubMed

    Wang, Zhenwen; Zhao, Jun; Chen, Min; Yang, Minhao; Tang, Luyang; Dang, Zhi-Min; Chen, Fenghua; Huang, Miaoming; Dong, Xia

    2014-11-26

    In this work, electrically and thermally actuated triple shape memory polymers (SMPs) of chemically cross-linked polycyclooctene (PCO)-multiwalled carbon nanotube (MWCNT)/polyethylene (PE) nanocomposites with co-continuous structure and selective distribution of fillers in PCO phase are prepared. We systematically studied not only the microstructure including morphology and fillers' selective distribution in one phase of the PCO/PE blends, but also the macroscopic properties including thermal, mechanical, and electrical properties. The co-continuous window of the immiscible PCO/PE blends is found to be the volume fraction of PCO (vPCO) of ca. 40-70 vol %. The selective distribution of fillers in one phase of co-continuous blends is obtained by a masterbatch technique. The prepared triple SMP materials show pronounced triple shape memory effects (SMEs) on the dynamic mechanical thermal analysis (DMTA) and the visual observation by both thermal and electric actuations. Such polyolefin samples with well-defined microstructure, electrical actuation, and triple SMEs might have potential applications as, for example, multiple autochoke elements for engines, self-adjusting orthodontic wires, and ophthalmic devices.

  6. Influence of blend microstructure on bulk heterojunction organic photovoltaic performance.

    PubMed

    Brabec, Christoph J; Heeney, Martin; McCulloch, Iain; Nelson, Jenny

    2011-03-01

    The performance of organic photovoltaic devices based upon bulk heterojunction blends of donor and acceptor materials has been shown to be highly dependent on the thin film microstructure. In this tutorial review, we discuss the factors responsible for influencing blend microstructure and how these affect device performance. In particular we discuss how various molecular design approaches can affect the thin film morphology of both the donor and acceptor components, as well as their blend microstructure. We further examine the influence of polymer molecular weight and blend composition upon device performance, and discuss how a variety of processing techniques can be used to control the blend microstructure, leading to improvements in solar cell efficiencies.

  7. Phase Segregation in Polystyrene?Polylactide Blends

    SciTech Connect

    Leung, Bonnie; Hitchcock, Adam; Brash, John; Scholl, Andreas; Doran, Andrew

    2010-06-09

    Spun-cast films of polystyrene (PS) blended with polylactide (PLA) were visualized and characterized using atomic force microscopy (AFM) and synchrotron-based X-ray photoemission electron microscopy (X-PEEM). The composition of the two polymers in these systems was determined by quantitative chemical analysis of near-edge X-ray absorption signals recorded with X-PEEM. The surface morphology depends on the ratio of the two components, the total polymer concentration, and the temperature of vacuum annealing. For most of the blends examined, PS is the continuous phase with PLA existing in discrete domains or segregated to the air?polymer interface. Phase segregation was improved with further annealing. A phase inversion occurred when films of a 40:60 PS:PLA blend (0.7 wt percent loading) were annealed above the glass transition temperature (Tg) of PLA.

  8. Covalent Fusion of layered Incompatible Gels in Immiscible Solvents

    NASA Astrophysics Data System (ADS)

    Biswas, Santidan; Singh, Awaneesh; Matyjaszewski, Krzysztof; Balazs, Anna C.

    We carry out dissipative particle dynamics (DPD) simulations to model a two layered stackable gel where the gels are incompatible and are present in immiscible solvent. The bottom layer of the gel is created first and then a solution of new initiators, monomers and cross-linkers is introduced on top of it. These components then undergo polymerization and form the second gel layer. We study all possible combinations of free radical polymerization (FRP) and atom transfer radical polymerization (ATRP) mechanisms with the two layers of the gel. For example, the bottom layer gel is created via ATRP, whereas the top layer gel follows FRP. Our focus is to do a systematic study of all these combinations and find out the factors responsible for combining two incompatible gels in immiscible solvents.

  9. Research aimed at immiscible CO/sub 2/ flooding

    SciTech Connect

    Chung, F.T.H.; Burchfield, T.E.

    1987-04-27

    The National Institute for Petroleum and Energy Research (Niper) is conducting reserach to develop improved methods for oil recovery by immiscible CO/sub 2/ displacement. The research includes fundamental studies of displacement mechanisms and coreflooding tests for development of an optimal injection method. Heavy oils are the major target of this research. For heavier crudes (API gravity below 25/sup 0/), high viscosity is a major constraint in oil recovery and pipeline transportation. Therefore, reducing oil viscosity becomes critical. Methods currently being used for viscous oil recovery include thermal methods (steamflooding and in situ combustion) and CO/sub 2/ methods. Steamflooding has been widely applied. The number of immiscible CO/sub 2/ projects is small but increasing.

  10. Immiscible fluid: Heat of fusion heat storage system

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Melsheimer, S. S.; Mullins, J. C.

    1980-01-01

    Both heat and mass transfer in direct contact aqueous crystallizing systems were studied as part of a program desig- ned to evaluate the feasibility of direct contact heat transfer in phase change storage using aqueous salt system. Major research areas, discussed include (1) crystal growth velocity study on selected salts; (2) selection of salt solutions; (3) selection of immiscible fluids; (4) studies of heat transfer and system geometry; and (5) system demonstration.

  11. Influence of Copolymer Composition on Morphology Development in Blends

    NASA Astrophysics Data System (ADS)

    Krishanmoorthy, Jayaraman

    2005-03-01

    Blends involving a crystallizable polyester [poly(hexamethylene adipate) (PHMA)] with an amorphous polyether has been studied. These systems have hydroxyl end groups which can react with diisocyanate in the presence of nucleophilic catalysts. These functionalized (isocyanate-terminated) polymer blends form the fundamental structure of polyurethanes. These prepolymers can then be cured at a later stage due to ambient water molecules. Thus the migration of water molecules through the morphology formed needs to be understood well. The morphology development (i.e. phase separation occurring concurrently with crystallization) of nascent polymer blends has been characterized. The morphology of functionalized polymers exhibit very different kinetics due to the presence of the small amount of copolymers formed. The ultimate morphology formed can be ``tuned'' by varying blend composition and crystallization conditions. The structures of prepolymers will be reported. The presence of this copolymer can significantly alter the structural transformation in either binary or ternary blends.

  12. Blending of n-type Semiconducting Polymer and PC61BM for an Efficient Electron-Selective Material to Boost the Performance of the Planar Perovskite Solar Cell.

    PubMed

    Seo, You-Hyun; Yeo, Jun-Seok; Myoung, NoSoung; Yim, Sang-Youp; Kang, Minji; Kim, Dong-Yu; Na, Seok-In

    2016-05-25

    The highly efficient CH3NH3PbI3 perovskite solar cell (PeSC) is simply achieved by employing a blended electron-transport layer (ETL) consisting of PC61BM and P(NDI2OD-T2). The high molecular weight of P(NDI2OD-T2) allows for a thinned ETL with a uniform morphology that optimizes the PC61BM ETL more effectively. As a result of this enhancement, the power conversion efficiency of a PC61BM:P(NDI2OD-T2)-based PeSC is 25% greater than that of the conventional PC61BM based-PeSC; additionally, the incorporation of P(NDI2OD-T2) into PC61BM attenuates the dependence of the PeSC on the ETL-processing conditions regarding its performance. It is revealed that, in addition to the desirable n-type semiconducting characteristics of PC61BM:P(NDI2OD-T2)-including a higher electron-mobility and a more-effective electron selectivity of a blended ETL for an efficient electron extraction-the superior performance of a PC61BM:P(NDI2OD-T2) device is the result of a thinned and uniformly covered ETL on the perovskite layer.

  13. Poly(anhydride-ester) and poly(N-vinyl-2-pyrrolidone) blends: salicylic acid-releasing blends with hydrogel-like properties that reduce inflammation.

    PubMed

    Ouimet, Michelle A; Fogaça, Renata; Snyder, Sabrina S; Sathaye, Sameer; Catalani, Luiz H; Pochan, Darrin J; Uhrich, Kathryn E

    2015-03-01

    Polymers such as poly(N-vinyl-2-pyrrolidone) (PVP) have been used to prepare hydrogels for wound dressing applications but are not inherently bioactive. For enhanced healing, PVP was blended with salicylic acid-based poly(anhydride-esters) (SAPAE) and shown to exhibit hydrogel properties upon swelling. In vitro release studies demonstrated that the chemically incorporated drug (SA) was released from the polymer blends over 3-4 d in contrast to 3 h, and that blends of higher PVP content displayed greater swelling values and faster SA release. The polymer blends significantly the inflammatory cytokine, TNF-α, in vitro without negative effects.

  14. Evaluation of the drug release patterns and long term stability of aqueous and organic coated pellets by using blends of enteric and gastrointestinal insoluble polymers.

    PubMed

    Kranz, H; Gutsche, S

    2009-10-01

    The major aim of this study was to identify an efficient tool to adjust drug release patterns from aqueous and organic ethylcellulose (a gastrointestinal insoluble polymer) coated pellets and to evaluate the long term stability of the film coatings. Drug release was monitored during open and closed storage at 25 degrees C/60% RH (ambient conditions) and 40 degrees C/75% RH (stress conditions) for up to 24 months. Release of vatalanib succinate, a poorly soluble drug that demonstrates pH-dependent solubility, from pure ethylcellulose coated pellets was slow irrespectively of the type of coating and release medium. By addition of the enteric polymer methacrylic acid/ethyl acrylate copolymer (applied as aqueous Kollicoat MAE 30 DP dispersion or organic solution of Kollicoat MAE 100 P) to ethylcellulose broad ranges of drug release patterns could be achieved. For aqueous film coatings the addition of Kollicoat MAE 30 DP to ethylcellulose dispersions resulted in unaltered drug release kinetics during closed storage at ambient and stress conditions. The storage stabilizing effect of the added enteric polymer might be explained by the more hydrophilic nature of Kollicoat MAE 30 DP compared to ethylcellulose trapping water during film formation and improving polymer particle coalescence. However, during open storage of aqueous coated ethylcellulose:Kollicoat MAE 30 DP pellets at stress conditions drug release decreased due to further gradual polymer particle coalescence. In contrast, drug release rates from organic coated ethylcellulose:Kollicoat MAE 100 P pellets stored at ambient and stress conditions did not change which could be explained by differences in the film formation process. This clearly indicates that the presented concept of the addition of methacrylic acid/ethyl acrylate copolymer to ethylcellulose film coatings in combination with an organic coating process is able to achieve broad ranges of drug release patterns and to overcome storage instability.

  15. Lattice Boltzmann equation method for multiple immiscible continuum fluids

    NASA Astrophysics Data System (ADS)

    Spencer, T. J.; Halliday, I.; Care, C. M.

    2010-12-01

    This paper generalizes the two-component algorithm of Sec. , extending it, in Sec. , to describe N>2 mutually immiscible fluids in the isothermal continuum regime. Each fluid has an independent interfacial tension. While retaining all its computational advantages, we remove entirely the empiricism associated with contact behavior in our previous multiple immiscible fluid models [M. M. Dupin , Phys. Rev. E 73, 055701(R) (2006)10.1103/PhysRevE.73.055701; Med. Eng. Phys. 28, 13 (2006)10.1016/j.medengphy.2005.04.015] while solidifying the physical foundations. Moreover, the model relies upon a fluid-fluid segregation which is simpler, computationally faster, more free of artifacts (i.e., the interfacial microcurrent), and upon an interface-inducing force distribution which is analytic. The method is completely symmetric between any numbers of immiscible fluids and stable over a wide range of directly input interfacial tension. We present data on the steady-state properties of multiple interface model, which are in good agreement with theory [R. E. Johnson and S. S. Sadhal, Annu. Rev. Fluid Mech. 17, 289 (1985)10.1146/annurev.fl.17.010185.001445], specifically on the shapes of multidrop systems. Section is an analysis of the kinetic and continuum-scale descriptions of the underlying two-component lattice Boltzmann model for immiscible fluids, extendable to more than two immiscible fluids. This extension requires (i) the use of a more local kinetic equation perturbation which is (ii) free from a reliance on measured interfacial curvature. It should be noted that viewed simply as a two-component method, the continuum algorithm is inferior to our previous methods, reported by Lishchuk [Phys. Rev. E 67, 036701 (2003)]10.1103/PhysRevE.76.036701 and Halliday [Phys. Rev. E 76, 026708 (2007)]10.1103/PhysRevE.76.026708. Greater stability and parameter range is achieved in multiple drop simulations by using the forced multi-relaxation-time lattice Boltzmann method developed

  16. Novel chemical route to prepare a new polymer blend gate dielectric for flexible low-voltage organic thin-film transistor.

    PubMed

    Meena, Jagan Singh; Chu, Min-Ching; Chang, Yu-Cheng; Wu, Chung-Shu; Cheng, Chih-Chia; Chang, Feng-Chih; Ko, Fu-Hsiang

    2012-06-27

    An organic-organic blend thin film has been synthesized through the solution deposition of a triblock copolymer (Pluronic P123, EO20-PO70-EO20) and polystyrene (PS), which is called P123-PS for the blend film whose precursor solution was obtained with organic additives. In addition to having excellent insulating properties, these materials have satisfied other stringent requirements for an optimal flexible device: low-temperature fabrication, nontoxic, surface free of pinhole defect, compatibility with organic semiconductors, and mechanical flexibility. Atomic force microscope measurements revealed that the optimized P123-PS blend film was uniform, crack-free, and highly resistant to moisture absorption on polyimide (PI) substrate. The film was well-adhered to the flexible Au/Cr/PI substrate for device application as a stable insulator, which was likely due to the strong molecular assembly that includes both hydrophilic and hydrophobic effects from the high molecular weights. The contact angle measurements for the P123-PS surface indicated that the system had a good hydrophobic surface with a total surface free energy of approximately 19.6 mJ m(-2). The dielectric properties of P123-PS were characterized in a cross-linked metal-insulator-metal structured device on the PI substrate by leakage current, capacitance, and dielectric constant measurements. The P123-PS film showed an average low leakage current density value of approximately 10(-10) A cm(-2) at 5-10 MV cm(-1) and large capacitance of 88.2 nF cm(-2) at 1 MHz, and the calculated dielectric constant was 2.7. In addition, we demonstrated an organic thin-film transistor (OTFT) device on a flexible PI substrate using the P123-PS as the gate dielectric layer and pentacene as the channel layer. The OTFT showed good saturation mobility (0.16 cm(2) V(-1) s(-1)) and an on-to-off current ratio of 5 × 10(5). The OTFT should operate under bending conditions; therefore flexibility tests for two types of bending modes

  17. Response to ``Comment on `Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends' '' [J. Chem. Phys. 138, 197101 (2013)

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Capaccioli, S.

    2013-05-01

    The Comment of Colmenero asserts no change in Fs(Q,t) of the poly(ethylene oxide) (PEO) chains in blends with poly(methyl methacrylate) on crossing times of about 1-2 ns in data obtained by neutron scattering experiments and simulations. The assertion is opposite to that reported in the original papers where the neutron data and simulations were published. To make this point clear, we cite the data and the very statements made in the original papers concluding that indeed in the time interval from 60 ps to 1-2 ns the dynamics of PEO chain follows approximately the Rouse model, but becomes slower and departs from the Rouse model in the dependencies on time, momentum transfer, and temperature at longer times past tc = 1-2 ns. It is noteworthy that similar crossover of chain dynamics in entangled homopolymers at the ns time scale was found by neutron scattering.

  18. PHA-rubber blends: synthesis, characterization and biodegradation.

    PubMed

    Bhatt, Rachana; Shah, Dishma; Patel, K C; Trivedi, Ujjval

    2008-07-01

    Medium chain length polyhydroxyalkanoates (mcl-PHA) and different rubbers; namely natural rubber, nitrile rubber and butadiene rubber were blended at room temperature using solution blending technique. Blends constituted 5%, 10% and 15% of mcl-PHA in different rubbers. Thermogravimetric analysis of mcl-PHA showed the melting temperature of the polymer around 50 degrees C. Thermal properties of the synthesized blend were studied by Differential Scanning Calorimetry which confirmed effective blending between the polymers. Blending of mcl-PHA with natural rubber led to the synthesis of a different polymer having the melting point of 90 degrees C. Degradation studies of the blends were carried out using a soil isolate, Pseudomonas sp. 202 for 30 days. Extracellular protein concentration as well as OD660 due to the growth of Pseudomonas sp. 202 was studied. The degradation of blended plastic material, as evidenced by % weight loss after degradation and increase in the growth of organism correlated with the amount of mcl-PHA present in the sample. Growth of Pseudomonas sp. 202 resulted in 14.63%, 16.12% and 3.84% weight loss of PHA:rubber blends (natural, nitrile and butadiene rubber). Scanning electron microscopic studies after 30 days of incubation further confirmed biodegradation of the films.

  19. Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

    SciTech Connect

    Spauschus, H.O.; Starr, T.L.

    1999-03-30

    A method is described for separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed. 3 figs.

  20. Aerogel/polymer composite materials

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  1. Quantitative evaluation of evaporation rate during spin-coating of polymer blend films: Control of film structure through defined-atmosphere solvent-casting.

    PubMed

    Mokarian-Tabari, P; Geoghegan, M; Howse, J R; Heriot, S Y; Thompson, R L; Jones, R A L

    2010-12-01

    Thin films of polymer mixtures made by spin-coating can phase separate in two ways: by forming lateral domains, or by separating into distinct layers. The latter situation (self-stratification or vertical phase separation) could be advantageous in a number of practical applications, such as polymer optoelectronics. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either self-stratification or lateral phase separation in the same system, and we relate this to a previously hypothesised mechanism for phase separation during spin-coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that rapid evaporation leads to a laterally phase-separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film.

  2. White Light from a Light-Emitting Electrochemical Cell: Controlling the Energy-Transfer in a Conjugated Polymer/Triplet-Emitter Blend.

    PubMed

    Tang, Shi; Buchholz, Herwig A; Edman, Ludvig

    2015-11-25

    We report on the attainment of broadband white light emission from a host-guest light-emitting electrochemical cell, comprising a blue-emitting conjugated polymer as the majority host and a red-emitting small-molecule triplet emitter as the minority guest. An analysis of the energy structure reveals that host-to-guest energy transfer can be effectuated by both Förster and Dexter processes, and through a careful optimization of the active material composition partial energy transfer and white emission is accomplished at a low guest concentration of 0.5%. By adding a small amount of a yellow-emitting conjugated polymer to the active material, white light emission with a high color rendering index of 79, and an efficiency of 4.3 cd/A at significant luminance (>200 cd/m(2)), is realized.

  3. Proton Conducting Polymer Electrolyte Based on Pva-Pan

    NASA Astrophysics Data System (ADS)

    Devi, S. Siva; Selvasekarapandian, S.; Rajeswari, N.; Genova, F. Kingslin Mary; Karthikeyan, S.; Raja, C. Sanjeevi

    2013-07-01

    Proton conducting polymer electrolytes based on blend polymer using Poly Vinyl Alcohol (PVA) and Poly Acrylo Nitrile (PAN) doped with ammonium nitrate have been prepared by solution casting method. The highest conductivity at room temperature (305K) has been found to be 1.8×10-3 S cm-1 for 15 mole % NH4NO3 doped PVA-PAN system. X ray Diffraction pattern of the doped and the undoped blend polymer electrolyte confirms the amorphous nature of blend polymer, when salt is added. The complex formation between the blend polymer and the salt has been confirmed by Fourier transform infrared spectroscopy.

  4. Compatibility study of alginate/keratin blend for biopolymer development.

    PubMed

    Gupta, Pratima; Nayak, Kush Kumar

    2015-12-18

    The ultimate characteristics of blend film depend on the properties of its polymeric components, composition, and on the compatibility of the polymers. Binary polymer blend films of alginate (ALG) and keratin (KER) fibers (obtained from chicken feathers) were prepared by simple solution casting techniques and their compatibility properties were studied by X-ray diffraction and scanning electron microscopy. The tensile strength and percent of elongation were measured by a tensile strength tester. The results of the present studies elucidate that ALG and KER are compatible and suitable for the development of a blend film. It was found that the ALG/KER blend ratios of 90:10 and 80:20 possess characteristics to make a blend film with a high tensile strength value. The blend with composition 90:10 of ALG/KER is the one of the strongest candidates in the preparation of blending films, because it has the highest tensile strength (0.38 MPa) and percentage of elongation (59.5%) among all tested blend compositions. The blend ratio of 80:20 of ALG/KER achieves maximum compatibility, since its intensity pattern changes drastically as recorded in an X-ray diffraction study. The fabricated blend film can be a suitable candidate for a range of biomaterials such as for a drug delivery vesicle, hydrogel, and scaffolding, etc.

  5. Effects of mixing temperature on mechanical properties of TPU/NR blends

    NASA Astrophysics Data System (ADS)

    Ahad, Nor Azwin; Ahmad, Sahrim Hj

    2013-05-01

    Blending method of two or more polymer is a well-established strategy to modify the physical properties without synthesizing the new polymer system. However, it is difficult to obtain homogeneous polymer blends because blending polymer requires suitable processing parameters. In this study, the effect of mixing temperature on tensile properties of the thermoplastic polyurethane (TPU) with natural rubber (NR) blends was investigated as the one of processing parameters in obtaining homogeneous polymer blends. The blends were prepared via melt blending technique with the different TPU wt% of 85, 65, 45 and 25 at four different mixing temperature; 180 °C, 190 °C, 200 °C and 210 7°C. The blend with 85% TPU shows the maximum tensile strength and elongation at breaks value at 180 %C mixing temperature. The viscosity of the polymer reduced at higher temperature. Also, the movements of molecules are more worthy because of poor molecule interaction. This will affect to mechanical properties of the blends. In general, it was observed that the mixing temperature is one of the important parameter in acquiring blends having optimum mechanical properties.

  6. Design, Development, and Optimization of Sterculia Gum-Based Tablet Coated with Chitosan/Eudragit RLPO Mixed Blend Polymers for Possible Colonic Drug Delivery.

    PubMed

    Nath, Bipul; Nath, Lila Kanta

    2013-01-01

    The purpose of this study is to explore the possible applicability of Sterculia urens gum as a novel carrier for colonic delivery system of a sparingly soluble drug, azathioprine. The study involves designing a microflora triggered colon-targeted drug delivery system (MCDDS) which consists of a central polysaccharide core and is coated to different film thicknesses with blends of chitosan/Eudragit RLPO, and is overcoated with Eudragit L00 to provide acid and intestinal resistance. The microflora degradation property of gum was investigated in rat caecal medium. Drug release study in simulated colonic fluid revealed that swelling force of the gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora-activated environment. Chitosan in the mixed film coat was found to be degraded by enzymatic action of the microflora in the colon. Release kinetic data revealed that the optimized MCDDS was fitted well into first-order model, and apparent lag time was found to be 6 hours, followed by Higuchi release kinetics. In vivo study in rabbits shows delayed T max, prolonged absorption time, decreased C max, and absorption rate constant (Ka), indicating a reduced systemic toxicity of the drug as compared to other dosage forms.

  7. Design, Development, and Optimization of Sterculia Gum-Based Tablet Coated with Chitosan/Eudragit RLPO Mixed Blend Polymers for Possible Colonic Drug Delivery

    PubMed Central

    Nath, Bipul; Nath, Lila Kanta

    2013-01-01

    The purpose of this study is to explore the possible applicability of Sterculia urens gum as a novel carrier for colonic delivery system of a sparingly soluble drug, azathioprine. The study involves designing a microflora triggered colon-targeted drug delivery system (MCDDS) which consists of a central polysaccharide core and is coated to different film thicknesses with blends of chitosan/Eudragit RLPO, and is overcoated with Eudragit L00 to provide acid and intestinal resistance. The microflora degradation property of gum was investigated in rat caecal medium. Drug release study in simulated colonic fluid revealed that swelling force of the gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora-activated environment. Chitosan in the mixed film coat was found to be degraded by enzymatic action of the microflora in the colon. Release kinetic data revealed that the optimized MCDDS was fitted well into first-order model, and apparent lag time was found to be 6 hours, followed by Higuchi release kinetics. In vivo study in rabbits shows delayed Tmax, prolonged absorption time, decreased Cmax, and absorption rate constant (Ka), indicating a reduced systemic toxicity of the drug as compared to other dosage forms. PMID:26555985

  8. Room temperature sputter deposited catalyst-free nanowires with wurtzite/zinc blende ZnO superstructure and their application in electromechanical nanogenerators on polymer and paper substrates.

    PubMed

    Borysiewicz, M A; Gryglas-Borysiewicz, M; Masłyk, M; Wojciechowski, T; Wzorek, M; Kaczmarski, J; Wojtowicz, T; Kamińska, E

    2017-02-24

    Catalyst-free growth of ZnO nanowires using reactive magnetron sputtering at room temperature is reported. We discuss the growth of the nanowires using reactive magnetron sputtering as a function of argon and oxygen flow values changing at a set ratio of 10:2. A transition from nanostructured Zn to nanowire ZnO growth is observed at 20 sccm Ar and 4 sccm O2. Densification and improved alignment of the nanowires is visible for increasing flow values up to 50 sccm Ar and 10 sccm O2. Nanowires exhibit stack