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Sample records for polymer film types

  1. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  2. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  3. Chain relaxation in thin polymer films: turning a dielectric type-B polymer into a type-A' one.

    PubMed

    Solar, Mathieu; Paul, Wolfgang

    2017-02-22

    A molecular dynamics simulation study of chain relaxation in a thin polymer film is presented, studying the dielectric response of a random copolymer of cis and trans 1,4-polybutadiene, a type B polymer without net chain dipole moment, confined between graphite walls. We stress the orientational effect of the attractive walls, inducing polarization in the vicinity of the walls, while the center of the film stays bulk-like. This polarization leads to a net dipole moment of the adsorbed chains, which is perpendicular to their end-to-end vector, which we termed as type A' behavior. In this situation, the dipole moment relaxes only upon desorption of the chains from the wall, a dynamic process which occurs on timescales much longer than the bulk relaxation time of the polymer.

  4. Effect of the polymer concentration on the Rayleigh-instability-type transformation in polymer thin films coated in the nanopores of anodic aluminum oxide templates.

    PubMed

    Tsai, Chia-Chan; Chen, Jiun-Tai

    2015-03-03

    We study the Rayleigh-instability-type transformation of polystyrene (PS) thin films coated in the nanopores of anodic aluminum oxide (AAO) templates. The PS thin films are fabricated using a solution-wetting method, in which the wall thicknesses are controlled by the concentrations of the polymer solutions and the diameters of the nanopores. By thermal annealing, the surfaces of the thin films undulate and the morphologies transform from nanotubes to Rayleigh-instability-induced nanostructures (short nanorods) and long nanorods. To understand the mechanism of the morphology transformation further, we construct the morphology diagrams by annealing the PS thin films at different temperatures and times. We observe that the morphology diagrams of the PS thin films prepared by different concentrations are similar, indicating that the transformation kinetics are not affected by the film thicknesses. The values of the undulation wavelengths, however, are controlled by the film thicknesses and the diameters of the nanopores.

  5. High-Performance Electrochromic Devices Based on Poly[Ni(salen)]-Type Polymer Films.

    PubMed

    Nunes, Marta; Araújo, Mariana; Fonseca, Joana; Moura, Cosme; Hillman, Robert; Freire, Cristina

    2016-06-08

    We report the application of two poly[Ni(salen)]-type electroactive polymer films as new electrochromic materials. The two films, poly[Ni(3-Mesalen)] (poly[1]) and poly[Ni(3-MesaltMe)] (poly[2]), were successfully electrodeposited onto ITO/PET flexible substrates, and their voltammetric characterization revealed that poly[1] showed similar redox profiles in LiClO4/CH3CN and LiClO4/propylene carbonate (PC), while poly[2] showed solvent-dependent electrochemical responses. Both films showed multielectrochromic behavior, exhibiting yellow, green, and russet colors according to their oxidation state, and promising electrochromic properties with high electrochemical stability in LiClO4/PC supporting electrolyte. In particular, poly[1] exhibited a very good electrochemical stability, changing color between yellow and green (λ = 750 nm) during 9000 redox cycles, with a charge loss of 34.3%, an optical contrast of ΔT = 26.2%, and an optical density of ΔOD = 0.49, with a coloration efficiency of η = 75.55 cm(2) C(-1). On the other hand, poly[2] showed good optical contrast for the color change from green to russet (ΔT = 58.5%), although with moderate electrochemical stability. Finally, poly[1] was used to fabricate a solid-state electrochromic device using lateral configuration with two figures of merit: a simple shape (typology 1) and a butterfly shape (typology 2); typology 1 showed the best performance with optical contrast ΔT = 88.7% (at λ = 750 nm), coloration efficiency η = 130.4 cm(2) C(-1), and charge loss of 37.0% upon 3000 redox cycles.

  6. Sandwich-type polymer nanofiber structure of poly(furfuryl alcohol): an effective template for ordered porous films.

    PubMed

    Gao, Feng; Lu, Qingyi; Pang, Huan; Komarneni, Sridhar

    2009-09-17

    A brand new sandwich-type poly(furfuryl alcohol) (PFA) nanostructure as well as ordered PFA nanofiber arrays has been successfully obtained through a novel two-step polymerization method by using a porous alumina membrane as the template. This novel structure is made up of ordered PFA nanopillars supported by two PFA films on the top and bottom. The thickness of the PFA films on both sides could be adjusted from several micrometers to tens of micrometers, and the flexibility of the membrane could be controlled in a certain range. This sandwich-type polymer nanostructure can be used as an effective template for constructing other ordered porous films resembling the structure of the parent alumina membrane, and in this study, ordered porous titania membrane has been successfully obtained. Theoretically, many other novel porous (or meso- and macro-mixed porous) materials could be synthesized through this novel template.

  7. Characterization of Nanostructured Polymer Films

    DTIC Science & Technology

    2014-12-23

    of the film for complete polymer chain relaxation, including relaxation of surface features . The presence of intact surface globules at a substrate...AFRL-OSR-VA-TR-2015-0059 Characterization of Nanostructured Polymer Films RODNEY PRIESTLEY TRUSTEES OF PRINCETON UNIVERSITY Final Report 12/23/2014...Report 3. DATES COVERED (From - To) 06/01/2012-08/31/2014 4. TITLE AND SUBTITLE Characterization of Nanostructured Polymer Films 5a. CONTRACT

  8. Dewetting of Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Dixit, P. S.; Sorensen, J. L.; Kent, M.; Jeon, H. S.

    2001-03-01

    DEWETTING OF THIN POLYMER FILMS P. S. Dixit,(1) J. L. Sorensen,(2) M. Kent,(2) H. S. Jeon*(1) (1) Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, jeon@nmt.edu (2) Department 1832, Sandia National Laboratories, Albuquerque, NM. Dewetting of thin polymer films is of technological importance for a variety of applications such as protective coatings, dielectric layers, and adhesives. Stable and smooth films are required for the above applications. Above the glass transition temperature (Tg) the instability of polymer thin films on a nonwettable substrate can be occurred. The dewetting mechanism and structure of polypropylene (Tg = -20 ^circC) and polystyrene (Tg = 100 ^circC) thin films is investigated as a function of film thickness (25 Åh < 250 Åand quenching temperature. Contact angle measurements are used in conjunction with optical microscope to check the surface homogeneity of the films. Uniform thin films are prepared by spin casting the polymer solutions onto silicon substrates with different contact angles. We found that the stable and unstable regions of the thin films as a function of the film thickness and quenching temperature, and then constructed a stability diagram for the dewetting of thin polymer films. We also found that the dewetting patterns of the thin films are affected substantially by the changes of film thickness and quenching temperature.

  9. Slow rupture of polymer films

    NASA Astrophysics Data System (ADS)

    Kliakhandler, Igor

    2004-11-01

    Bursting of soap film is a fast and fascinating process. It turns out that certain polymer films rupture in a somewhat similar fashion, but much slower. The slowness of the process allows one to study the rupture of polymer films with details. The rupture process in Hele-Shaw-like fashion shows remarkable properties, and is a very simple system. It turns out that propagation speed of the rupture is a function of the film thickness, and rheologic properties of the polymer. Experimental results will be compared with theory, together with demonstration of the experiment.

  10. Seebeck Effects in N-Type and P-Type Polymers Driven Simultaneously by Surface Polarization and Entropy Differences Based on Conductor/Polymer/Conductor Thin-Film Devices

    SciTech Connect

    Hu, Dehua; Liu, Qing; Tisdale, Jeremy; Lei, Ting; Pei, Jian; Wang, Hsin; Urbas, Augustine; Hu, Bin

    2015-04-15

    This paper reports Seebeck effects driven by both surface polarization difference and entropy difference by using intramolecular charge-transfer states in n-type and p-type conjugated polymers, namely IIDT and IIDDT, based on vertical conductor/polymer/conductor thin-film devices. Large Seebeck coefficients of -898 V/K and 1300 V/K from are observed from n-type IIDT p-type IIDDT, respectively, when the charge-transfer states are generated by a white light illumination of 100 mW/cm2. Simultaneously, electrical conductivities are increased from almost insulating states in dark condition to conducting states under photoexcitation in both n-type IIDT and p-type IIDDT devices. We find that the intramolecular charge-transfer states can largely enhance Seebeck effects in the n-type IIDT and p-type IIDDT devices driven by both surface polarization difference and entropy difference. Furthermore, the Seebeck effects can be shifted between polarization and entropy regimes when electrical conductivities are changed. This reveals a new concept to develop Seebeck effects by controlling polarization and entropy regimes based on charge-transfer states in vertical conductor/polymer/conductor thin-film devices.

  11. Seebeck Effects in N-Type and P-Type Polymers Driven Simultaneously by Surface Polarization and Entropy Differences Based on Conductor/Polymer/Conductor Thin-Film Devices

    DOE PAGES

    Hu, Dehua; Liu, Qing; Tisdale, Jeremy; ...

    2015-04-15

    This paper reports Seebeck effects driven by both surface polarization difference and entropy difference by using intramolecular charge-transfer states in n-type and p-type conjugated polymers, namely IIDT and IIDDT, based on vertical conductor/polymer/conductor thin-film devices. Large Seebeck coefficients of -898 V/K and 1300 V/K from are observed from n-type IIDT p-type IIDDT, respectively, when the charge-transfer states are generated by a white light illumination of 100 mW/cm2. Simultaneously, electrical conductivities are increased from almost insulating states in dark condition to conducting states under photoexcitation in both n-type IIDT and p-type IIDDT devices. We find that the intramolecular charge-transfer states canmore » largely enhance Seebeck effects in the n-type IIDT and p-type IIDDT devices driven by both surface polarization difference and entropy difference. Furthermore, the Seebeck effects can be shifted between polarization and entropy regimes when electrical conductivities are changed. This reveals a new concept to develop Seebeck effects by controlling polarization and entropy regimes based on charge-transfer states in vertical conductor/polymer/conductor thin-film devices.« less

  12. Thin film-coated polymer webs

    DOEpatents

    Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

    1992-02-04

    The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

  13. Structure and properties of polypropylene cast films: Polymer type and processing effects

    NASA Astrophysics Data System (ADS)

    Mileva, Daniela; Gahleitner, Markus; Gloger, Dietrich

    2016-05-01

    The influence of processing parameters in a cast film extrusion process of thin films of isotactic polypropylene homopolymer and random propylene-ethylene copolymer was analyzed. Variation of the chill roll temperature allowed changing the supercooling of the melt and thus the generation of different crystal polymorphs of iPP. Additional focus was placed on the effect of flow induced crystallization via changing the output rate of the line. The crystal structure and morphology of the materials were evaluated and correlated to selected optical and mechanical properties.

  14. 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.

  15. Ultrathin Polymer Films for Microlithography

    DTIC Science & Technology

    1988-07-13

    exposure the PINAA was developed in a solution made of 3:7 cellosolve : methanol for 13 seconds. Cellosolve was chosen because it is strong enough to...can achieve on thicker resist (> 100 nm) for the same exposure conditions. Recently, we have exposed 14.3 nrm L-B PMMA films on a high resolution...Polymer Films LB PMMA Spin-Cast PNMA Spin-Cast Novolac (10 wafers) (5 wafers) (5 wafers) Film Thickness 14.3 nrm 14 nrm 22 nm Pinhole Density < 10/cm 2

  16. Seebeck effects in n-type and p-type polymers driven simultaneously by surface polarization and entropy differences based on conductor/polymer/conductor thin-film devices.

    PubMed

    Hu, Dehua; Liu, Qing; Tisdale, Jeremy; Lei, Ting; Pei, Jian; Wang, Hsin; Urbas, Augustine; Hu, Bin

    2015-05-26

    This paper reports Seebeck effects driven by both surface polarization difference and entropy difference by using photoinduced intramolecular charge-transfer states in n-type and p-type conjugated polymers, namely IIDT and IIDDT, respectively, based on vertical conductor/polymer/conductor thin-film devices. We obtain large Seebeck coefficients of -898 μV/K from n-type IIDT and 1300 μV/K from p-type IIDDT when the charge-transfer states are generated by a white light illumination of 100 mW/cm(2), compared with the values of 380 and 470 μV/K in dark condition, respectively. Simultaneously, the electrical conductivities are increased from almost insulating state in dark condition to conducting state under photoexcitation in both n-type IIDT and p-type IIDDT based devices. The large Seebeck effects can be attributed to the following two mechanisms. First, the intramolecular charge-transfer states exhibit strong electron-phonon coupling, which leads to a polarization difference between high and low temperature surfaces. This polarization difference essentially forms a temperature-dependent electric field, functioning as a new driving force additional to entropy difference, to drive the energetic carriers for the development of Seebeck effects under a temperature difference. Second, the intramolecular charge-transfer states generate negative or positive majority carriers (electrons or holes) in the n-type IIDT or p-type IIDDT, ready to be driven between high and low temperature surfaces for developing Seebeck effects. On the basis of coexisted polarization difference and entropy difference, the intramolecular charge-transfer states can largely enhance the Seebeck effects in both n-type IIDT and p-type IIDDT devices. Furthermore, we find that changing electrical conductivity can switch the Seebeck effects between polarization and entropy regimes when the charge-transfer states are generated upon applying photoexcitation. Therefore, using intramolecular charge

  17. Polymer film composite transducer

    DOEpatents

    Owen, Thomas E.

    2005-09-20

    A composite piezoelectric transducer, whose piezoeletric element is a "ribbon wound" film of piezolectric material. As the film is excited, it expands and contracts, which results in expansion and contraction of the diameter of the entire ribbon winding. This is accompanied by expansion and contraction of the thickness of the ribbon winding, such that the sound radiating plate may be placed on the side of the winding.

  18. Dewetting of thin-film polymers.

    PubMed

    Saulnier, F; Raphaël, E; De Gennes, P-G

    2002-12-01

    In this paper we present a theoretical model for the dewetting of ultrathin polymer films. Assuming that the shear-thinning properties of these films can be described by a Cross-type constitutive equation, we analyze the front morphology of the dewetting film, and characterize the time evolution of the dry region radius, and of the rim height. Different regimes of growth are expected, depending on the initial film thickness, and on the power-law index involved in the constitutive equation. In the thin-films regime, the dry radius and the rim height obey power-law time dependences. We then compare our predictions with the experimental results obtained by Debrégeas et al. [Phys. Rev. Lett. 75, 3886 (1995)] and by Reiter [Phys. Rev. Lett. 87, 186101 (2001)].

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

    PubMed

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

    2017-01-18

    Bandgap engineering of kesterite Cu2Zn(Sn, Ge)(S, Se)4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu2Zn(Sn, Ge)(S, Se)4 thin films with tunable bandgap. The bandgap of Cu2Zn(Sn, Ge)(S, Se)4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu2Zn(Sn, Ge)(S, Se)4 thin films exhibits a hall coefficient of +137 cm(3)/C. The resistivity, concentration and carrier mobility of the Cu2ZnSn(S, Se)4 thin film are 3.17 ohm·cm, 4.5 × 10(16) cm(-3), and 43 cm(2)/(V·S) at room temperature, respectively. Moreover, the Cu2ZnSn(S, Se)4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu2Zn(Sn, Ge)(S, Se)4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  20. Preparation of patterned ultrathin polymer films.

    PubMed

    Yang, Huige; Su, Meng; Li, Kaiyong; Jiang, Lei; Song, Yanlin; Doi, Masao; Wang, Jianjun

    2014-08-12

    Though patterned ultrathin polymer films (<100 nm) are of great importance in the fields of sensors and nanoelectronic devices, the fabrication of patterned ultrathin polymer films remains a great challenge. Herein, patterned ultrathin polymer films are fabricated facilely on hydrophobic substrates with different hydrophilic outline patterns by the pinning of three-phase contact lines of polymer solution on the hydrophilic outlines. This method is universal for most of the water-soluble polymers, and poly(vinyl alcohol) (PVA) has been selected as a model polymer due to its biocompatibility and good film-forming property. The results indicate that the morphologies of ultrathin polymer films can be precisely adjusted by the size of the hydrophilic outline pattern. Specifically, patterned hydrophilic outlines with sizes of 100, 60, and 40 μm lead to the formation of concave-shaped ultrathin PVA films, whereas uniform ultrathin PVA films are formed on 20 and 10 μm patterned substrates. The controllabilities of morphologies can be interpreted through the influences of the slip length and coffee ring effect. Theoretical analysis shows that when the size of the hydrophilic outline patterns is smaller than a critical value, the coffee ring effect disappears and uniform patterned ultrathin polymer films can be formed for all polymer concentrations. These results provide an effective methodology for the fabrication of patterned ultrathin polymer films and enhance the understanding of the coffee ring effect.

  1. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

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

    2014-06-17

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

  2. Semiconductor-nanocrystal/conjugated polymer thin films

    DOEpatents

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

    2010-08-17

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

  3. Liquid film/polymer interfaces

    SciTech Connect

    Allara, David L.

    2003-06-12

    The objectives were: (1) Through experimental studies, advance the fundamental understanding of the principles that govern adsorption and wetting phenomena at polymer and organic surfaces. (2) Establish a firm scientific basis for improving the design of coatings for metal fin cooling surfaces used to control the wetting of water condensate for optimum energy efficiency. Several important findings were: (1) water adsorbed at hydrophobic surfaces has a liquid-like structure, in contrast to the generally held view of an ordered structure; (2) Correlations of large amounts of contact angle wetting data of grafted alkyl chain compounds showed a distinct link between the contact angle and the conformational ordering of the chains; (3) water adsorption at long chain alkysiloxane films showed a strong pH dependence on the film stability, which can be attributed to interfacial chemical effects on the siloxane network.

  4. Acoustical performance of an electrostrictive polymer film loudspeaker

    PubMed

    Heydt; Pelrine; Joseph; Eckerle; Kornbluh

    2000-02-01

    A new type of loudspeaker that generates sound by means of the electrostrictive response of a thin polymer film is described. Electrostrictive polymer film (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have a very low profile. The films are typically silicone and are coated with compliant electrodes to allow large film deformations. Acoustical frequency response measurements from 5 x 5 cm (planar dimensions) prototype EPF loudspeakers are presented. Measurements of harmonic distortion are also shown, along with results demonstrating reduced harmonic distortion achieved with square-root wave shaping. Applications of EPF loudspeakers include active noise control and general-purpose flat-panel loudspeakers.

  5. High temperature polymer dielectric film insulation

    NASA Technical Reports Server (NTRS)

    Jones, Robert J.

    1994-01-01

    PFPI polymers were invented in the late 1970's. Assessment of emerging requirements has dictated that 300 C performance is the goal for next generation wire insulation. TRW PFPI as superior 300 C polymer candidates is presented. Included is a comparison of promising PFPI film properties with Kapton. Also included are the promising bulk polymer or coating properties.

  6. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, Kevin M.; Watson, Lloyd D.; McAtee, Richard E.; Ploger, Scott A.

    1993-01-01

    A method of forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous.

  7. Spray forming polymer membranes, coatings and films

    DOEpatents

    McHugh, K.M.; Watson, L.D.; McAtee, R.E.; Ploger, S.A.

    1993-10-12

    A method is described for forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous. 4 figures.

  8. Preparation and characterization of gradient polymer films

    SciTech Connect

    Smith, S.C.

    1987-01-01

    Gradient polymers are multicomponent polymers whose chemical constitution varies with depth in the sample. Although these polymers may possess unique mechanical, optical, and barrier properties they remain relatively unexplored. This work is a study of the preparation of gradient polymers by sequential exposure of films to a diffusing monomer followed by electron beam irradiation. Initial experiments involved immersion of poly(vinyl chloride) (PVC) films in styrene or n-butyl methacrylate (BMA) for various time periods followed by irradiation with 1 or 10 megarads of accelerated electrons. A significant amount of poly(n-butyl methacrylate) (PBMA) formed in PVC/BMA systems, but little polystyrene could be found in the PVC/styrene films. A second set of experiments involved immersion of PVC and polyethylene (PE) films in BMA for 20, 40, 60, and 720 minutes followed by irradiation with 10 megarads of electrons. These films were then characterized using optical microscopy, quantitative transmission Fourier transform infrared spectroscopy (FTIR), and a depth profiling procedure based on quantitative attenuated total reflection (ATR) FTIR. It was concluded that the mechanism of PBMA formation in the polyethylene films was a result of events immediately following irradiation. Atmospheric oxygen diffusing into irradiated films trapped free radicals at the film surfaces. This was followed by storage in an evacuated desiccator where unintentional exposure to BMA vapor took place. This BMA reacted with free radicals that remained within the film cores, polymerizing to PBMA.

  9. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

    1992-04-28

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol. 2 figs.

  10. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, Israel; Gottesfeld, Shimshon; Sabatani, Eyal

    1992-01-01

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventioonally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

  11. High Dielectric Constant Polymer Film Capacitors (PREPRINT)

    DTIC Science & Technology

    2010-02-01

    film, and the test of our first generation prototype capacitors . High-K Polymeric Dielectrics Commercial polypropylene (PP) capacitor film has a...1994). 2. Maurizio Rabuffi and Guido Picci, “Status Quo and Future Prospects for Metallized Polypropylene Energy Storage Capacitors ”, IEEE Trans...AFRL-RZ-WP-TP-2010-2126 HIGH DIELECTRIC CONSTANT POLYMER FILM CAPACITORS (PREPRINT) Shihai Zhang, Brian Zellers, Dean Anderson, Paul

  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. Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition.

    PubMed

    Kwon, Oh-Yun; Na, Hyun-Jun; Kim, Hyung-Jun; Lee, Dong-Won; Nam, Song-Min

    2012-05-22

    Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite films are formed with different characteristics - surface morphologies, deposition rates, and crystallite size of α-Al2O3. Through the results of micro-Vickers hardness testing, it was confirmed that the mechanical properties of the polymer itself are associated with the performances of the ceramic-polymer composite films. To support and explain these results, the microstructures of the two types of polymer powders were observed after planetary milling and an additional modeling test was carried out. As a result, we could conclude that the PMMA powder is distorted by the impact of the Al2O3 powder, so that the resulting Al2O3-PMMA composite film had a very small amount of PMMA and a low deposition rate. In contrast, when using PI powder, the Al2O3-PI composite film had a high deposition rate due to the cracking of PI particles. Consequently, it was revealed that the mechanical properties of polymers have a considerable effect on the properties of the resulting ceramic-polymer composite thick films.

  14. Mesoscale morphologies in polymer thin films.

    SciTech Connect

    Ramanathan, M.; Darling, S. B.

    2011-06-01

    In the midst of an exciting era of polymer nanoscience, where the development of materials and understanding of properties at the nanoscale remain a major R&D endeavor, there are several exciting phenomena that have been reported at the mesoscale (approximately an order of magnitude larger than the nanoscale). In this review article, we focus on mesoscale morphologies in polymer thin films from the viewpoint of origination of structure formation, structure development and the interaction forces that govern these morphologies. Mesoscale morphologies, including dendrites, holes, spherulites, fractals and honeycomb structures have been observed in thin films of homopolymer, copolymer, blends and composites. Following a largely phenomenological level of description, we review the kinetic and thermodynamic aspects of mesostructure formation outlining some of the key mechanisms at play. We also discuss various strategies to direct, limit, or inhibit the appearance of mesostructures in polymer thin films as well as an outlook toward potential areas of growth in this field of research.

  15. High performance p-type organic thin film transistors with an intrinsically photopatternable, ultrathin polymer dielectric layer☆

    PubMed Central

    Petritz, Andreas; Wolfberger, Archim; Fian, Alexander; Krenn, Joachim R.; Griesser, Thomas; Stadlober, Barbara

    2013-01-01

    A high-performing bottom-gate top-contact pentacene-based oTFT technology with an ultrathin (25–48 nm) and electrically dense photopatternable polymeric gate dielectric layer is reported. The photosensitive polymer poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) is patterned directly by UV-exposure (λ = 254 nm) at a dose typical for conventionally used negative photoresists without the need for any additional photoinitiator. The polymer itself undergoes a photo-Fries rearrangement reaction under UV illumination, which is accompanied by a selective cross-linking of the macromolecules, leading to a change in solubility in organic solvents. This crosslinking reaction and the negative photoresist behavior are investigated by means of sol–gel analysis. The resulting transistors show a field-effect mobility up to 0.8 cm2 V−1 s−1 at an operation voltage as low as −4.5 V. The ultra-low subthreshold swing in the order of 0.1 V dec−1 as well as the completely hysteresis-free transistor characteristics are indicating a very low interface trap density. It can be shown that the device performance is completely stable upon UV-irradiation and development according to a very robust chemical rearrangement. The excellent interface properties, the high stability and the small thickness make the PNDPE gate dielectric a promising candidate for fast organic electronic circuits. PMID:24748853

  16. Antimicrobial polymer films for food packaging

    NASA Astrophysics Data System (ADS)

    Concilio, S.; Piotto, S.; Sessa, L.; Iannelli, P.; Porta, A.; Calabrese, E. C.; Galdi, M. R.; Incarnato, L.

    2012-07-01

    New antimicrobial polymeric systems were realized introducing new antimicrobial azo compounds in PP and LDPE matrices. The polymeric materials containing different percentage of azo compounds were mold-casted and the obtained film were tested in vitro against Gram+ and Gram- bacteria and fungi. These results hold promise for the fabrication of bacteria-resistant polymer films by means of simple melt processing with antimicrobial azo-dyes.

  17. Photovoltaic properties of polymer films

    NASA Astrophysics Data System (ADS)

    Reucroft, P. J.; Ullal, H.

    1980-03-01

    The effect of metal electrode and film thickness on the photovoltaic energy conversion efficiency in (1:1) mole ratio films of poly (N-vinylcarbazole) (PVK) and 2,4,7-trinitrofluorenone (TNF) has been investigated. Low work function metals increase the Schottky barrier height which leads to increases in the photovoltaic energy conversion efficiency. A ten-fold decrease in film thickness produces a thousand-fold increase in photovoltaic energy conversion efficiency. A theoretical model which assumes that the photovoltaic current is limited by Child's law predicts photovoltaic efficiencies which are in good agreement with the measured efficiencies.

  18. 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.

  19. Inorganic-polymer-derived dielectric films

    DOEpatents

    Brinker, C. Jeffrey; Keefer, Keith D.; Lenahan, Patrick M.

    1987-01-01

    A method of coating a substrate with a thin film of a polymer of predetermined porosity comprises depositing the thin film on the substrate from a non-gelled solution comprising at least one hydrolyzable metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base, prior to depositing the film, controlling the structure of the polymer for a given composition of the solution exclusive of the acid or base component and the water component, (a) by adjusting each of the water content, the pH, and the temperature to obtain the desired concentration of alkoxide, and then adjusting the time of standing of the solution prior to lowering the temperature of the solution, and (b) lowering the temperature of the solution after the time of standing to about 15 degrees C. or lower to trap the solution in a state in which, after the depositing step, a coating of the desired porosity will be obtained, and curing the deposited film at a temperature effective for curing whereby there is obtained a thin film of a polymer of a predetermined porosity and corresponding pore size on the substrate.

  20. Inkjet-printed flexible organic thin-film thermoelectric devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s/polymer composites through ball-milling

    PubMed Central

    Jiao, Fei; Di, Chong-an; Sun, Yimeng; Sheng, Peng; Xu, Wei; Zhu, Daoben

    2014-01-01

    In this article, we put forward a simple method for the synthesis of thermoelectric (TE) composite materials. Both n- and p-type composites were obtained by ball-milling the insoluble and infusible metal coordination polymers with other polymer solutions. The particle size, film morphology and composition were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TE properties of the drop-cast composite film were measured at different temperatures. An inkjet-printed flexible device was fabricated and the output voltage and short-circuit current at various hot-side temperatures (Thot) and temperature gradients (ΔT) were tested. The composite material not only highly maintained the TE properties of the pristine material but also greatly improved its processability. This method can be extended to other insoluble and infusible TE materials for solution-processed flexible TE devices. PMID:24615147

  1. 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).

  2. Membranes and Films from Polymers.

    ERIC Educational Resources Information Center

    Blumberg, Avrom A.

    1986-01-01

    Provides background information on polymeric films and membranes including production methods, special industrial and medical applications, laboratory preparation, and an experimental investigation of a porous cellulose acetate membrane. Presents a demonstration to distinguish between high- and low-density polyethylene. (JM)

  3. MISSE 6 Polymer Film Tensile Experiment

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K. R.; Dever, Joyce A.; Banks, Bruce A.; Waters, Deborah L.; Sechkar, Edward; Kline, Sara

    2010-01-01

    The Polymer Film Tensile Experiment (PFTE) was flown as part of Materials International Space Station Experiment 6 (MISSE 6). The purpose of the experiment was to expose a variety of polymer films to the low Earth orbital environment under both relaxed and tension conditions. The polymers selected are those commonly used for spacecraft thermal control and those under consideration for use in spacecraft applications such as sunshields, solar sails, and inflatable and deployable structures. The dog-bone shaped samples of polymers that were flown were exposed on both the side of the MISSE 6 Passive Experiment Container (PEC) that was facing into the ram direction (receiving atomic oxygen, ultraviolet (UV) radiation, ionizing radiation, and thermal cycling) and the wake facing side (which was supposed to have experienced predominantly the same environmental effects except for atomic oxygen which was present due to reorientation of the International Space Station). A few of the tensile samples were coated with vapor deposited aluminum on the back and wired to determine the point in the flight when the tensile sample broke as recorded by a change in voltage that was stored on battery powered data loggers for post flight retrieval and analysis. The data returned on the data loggers was not usable. However, post retrieval observation and analysis of the samples was performed. This paper describes the preliminary analysis and observations of the polymers exposed on the MISSE 6 PFTE.

  4. Thin Polymer Films Containing Carbon Nanostructures

    NASA Astrophysics Data System (ADS)

    Paszkiewicz, S.; Piesowicz, E.; Irska, I.; Roslaniec, Z.; Szymczyk, A.; Pawelec, I.

    2016-05-01

    Within the framework of the presented paper, the research experiments were conducted on the preparation and characterization of polymer thin films containing carbon nanotubes, graphene derivatives and hybrid systems of both CNTs/graphene derivatives, in which condensation polymers constituted the matrix. The use of in situ synthesis allowed to obtain nanocomposites with a high degree of homogeneity, which is a key issue for further industrial applications, while the analysis of the physical properties of the obtained materials showed effect of the addition of carbon nanotubes and graphene derivatives on their structure, barrier properties and thermal and electrical conductivity.

  5. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  6. Germanium films by polymer-assisted deposition

    DOEpatents

    Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

    2013-01-15

    Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

  7. Updated evaluation of polymer films for electrical insulation

    SciTech Connect

    McCoy, H.E. Jr.

    1990-08-01

    Several types of tests have been run on polymer film materials that could be useful for electrical insulation. The polymers studied were polyethylene terephtalate, polycarbonate, polysulfone, polyetherimide, ultrahigh-molecular-weight polyethylene, polyimide, polybutylene terephthalate, and a laminate of Kraft paper and polypropylene. Thermal aging tests were run to 60,000 h on several of the polymers, and the samples were evaluated by tensile tests, electrical breakdown tests, and immersion density measurements. Because of the wide range of potential service conditions, tensile tests were run on as-received materials over the temperature range of {minus}196 to 200{degree}C. Polyimide is probably the only material suitable for the extremes of this temperature range, but many of the other polymers would be suitable for intermediate temperatures. Creep tests were run in nitrogen and transformer oil at 90{degree}C. It was found that some polymers are weaker and less ductile in oil than in nitrogen and that other polymers have equivalent properties in the two environments. A means of applying mechanical, thermal, and electrical stresses simultaneously to polymer samples was developed. Tests were run at 90{degree}C in transformer oil on polyethylene terephthalate, polyimide, and polyethersulfone. Tests thus far do not indicate that the creep rate is affected by the application of a 5 kV dc potential. 7 refs., 30 figs., 16 tabs.

  8. Microfilm--Which Film Type, Which Application?

    ERIC Educational Resources Information Center

    Dodson, Suzanne Cates

    1985-01-01

    Report on characteristics of different kinds of microfilm available indicates proper film for specific needs. Silver halide and nonsilver films, diazo film, vesicular film, reaction of films to light, effect of heat and humidity on films, film susceptibility to scratching, and potential longevity of film types are covered. (35 references) (EJS)

  9. Scanning Tunneling Microscopy analysis of space-exposed polymer films

    NASA Technical Reports Server (NTRS)

    Kalil, Carol R.; Young, Philip R.

    1993-01-01

    The characterization of the surface of selected space-exposed polymer films by Scanning Tunneling Microscopy (STM) is reported. Principles of STM, an emerging new technique for materials analysis, are reviewed. The analysis of several films which received up to 5.8 years of low Earth orbital (LEO) exposure onboard the NASA Long Duration Exposure Facility (LDEF) is discussed. Specimens included FEP Teflon thermal blanket material, Kapton film, and several experimental polymer films. Ultraviolet and atomic oxygen-induced crazing and erosion are described. The intent of this paper is to demonstrate how STM is enhancing the understanding of LEO space environmental effects on polymer films.

  10. Nanoscale imaging of nonequilibrium polymer films

    NASA Astrophysics Data System (ADS)

    King, John; Granick, Steve

    2015-03-01

    In recent years there have been exciting advances in sub-diffraction limited imaging based on fluorescence microscopy. While most applications of super-resolution microscopy focus on static biological imaging, we are interested in extending these techniques to the study of polymer dynamics. To this end, we couple stimulated emission depletion (STED) with spectroscopic detection, relying on spectral features of fluorescence emission to serve as the imaging contrast agent. We aim to adapt fluorescent dyes responsive to environmental properties (polarity, mobility, current, temperature, ect.) to STED imaging. Using the fluorescent spectral response as a contrast agent allows for nanoscopic environments to be directly imaged without the need for specific labeling. Rapid acquisition of images allows for slow dynamic processes in nonequilibrium polymer films to be imaged in real time. We demonstrate the power of super-resolution spectroscopic imaging by directly imaging several topical problems in materials science.

  11. Fluoro-Substituted n-Type Conjugated Polymers for Additive-Free All-Polymer Bulk Heterojunction Solar Cells with High Power Conversion Efficiency of 6.71.

    PubMed

    Jung, Jae Woong; Jo, Jea Woong; Chueh, Chu-Chen; Liu, Feng; Jo, Won Ho; Russell, Thomas P; Jen, Alex K-Y

    2015-06-03

    Fluorinated n-type conjugated polymers are used as efficient electron acceptor to demonstrate high-performance all-polymer solar cells. The exciton generation, dissociation, and charge-transporting properties of blend films are improved by using these fluorinated n-type polymers to result in enhanced photocurrent and suppressed charge recombination.

  12. Polymer compositions, polymer films and methods and precursors for forming same

    SciTech Connect

    Klaehn, John R; Peterson, Eric S; Orme, Christopher J

    2013-09-24

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  13. 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.

  14. Hot pen and laser writable photonic polymer films

    NASA Astrophysics Data System (ADS)

    Moirangthem, Monali; Stumpel, Jelle E.; Alp, Baran; Teunissen, Pit; Bastiaansen, Cees W. M.; Schenning, Albertus P. H. J.

    2016-03-01

    An orange-reflecting photonic polymer film has been fabricated based on a hydrogen-bonded cholesteric liquid crystalline (CLC) polymer consisting of non-reactive (R)-(+)-3-methyladipic acid as the chiral dopant. This polymer film can be patterned easily by evaporating the chiral dopant at specific locations with a hot pen or a laser beam. Removal of chiral dopant leads to a decrease in the helical pitch at the heat treated areas leading to a change in color from orange to green revealing a high contrast pattern. The photonic patterns are irreversible and stable at ambient conditions. This makes such a CLC polymer film interesting as writable photonic paper.

  15. Structure in Thin and Ultrathin Spin-Cast Polymer Films

    NASA Astrophysics Data System (ADS)

    Frank, C. W.; Rao, V.; Despotopoulou, M. M.; Pease, R. F. W.; Hinsberg, W. D.; Miller, R. D.; Rabolt, J. F.

    1996-08-01

    The molecular organization in ultrathin polymer films (thicknesses less than 1000 angstroms) and thin polymer films (thicknesses between 1000 and 10,000 angstroms) may differ substantially from that of bulk polymers, which can lead to important differences in resulting thermophysical properties. Such constrained geometry films have been fabricated from amorphous poly(3-methyl-4-hydroxy styrene) (PMHS) and semicrystalline poly(di-n-hexyl silane) (PD6S) by means of spin-casting. The residual solvent content is substantially greater in ultrathin PMHS films, which suggests a higher glass transition temperature that results from a stronger hydrogen-bonded network as compared with that in thicker films. Crystallization of PD6S is substantially hindered in ultrathin films, in which a critical thickness of 150 angstroms is needed for crystalline morphology to exist and in which the rate of crystallization is initially slow but increases rapidly as the film approaches 500 angstroms in thickness.

  16. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, Terje A.; Lee, Hung S.; Okamoto, Yoshiyuki

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  17. Preparation of thin polymer films for infrared reaction rate studies

    NASA Technical Reports Server (NTRS)

    Garrard, G. G.; Houston, D. W.

    1970-01-01

    Procedure for preparing thin films for infrared spectrophotometric analysis involves pressing of a neat mixture of reactants between nonreactive thin polymer films with noninterfering absorption bands. Pressing is done under a pressure that gives desirable thickness. Following this process, the film sandwich is cut to accommodate the laboratory instrument.

  18. Synthesis and Characterization of Thin Film Lithium-Ion Batteries Using Polymer Electrolytes

    NASA Technical Reports Server (NTRS)

    Maranchi, Jeffrey P.; Kumta, Prashant N.; Hepp, Aloysius F.; Raffaelle, Ryne P.

    2002-01-01

    The present paper describes the integration of thin film electrodes with polymer electrolytes to form a complete thin film lithium-ion battery. Thin film batteries of the type, LiCoO2 [PAN, EC, PC, LiN(CF3SO2)2] SnO2 have been fabricated. The results of the synthesis and characterization studies will be presented and discussed.

  19. Thermochemical study of amino acid imprinted polymer films.

    PubMed

    Chai, Ziyi; BelBruno, Joseph J

    2015-11-01

    Molecularly imprinted polymers provide an alternative to traditional methods of amino acid analysis. The imprinted polymers are more robust and significantly less expensive than, for example, ELISA analysis. Amino acid imprinted nylon-6 thin films were studied by differential scanning calorimetry and scanning electron microscopy. Endothermic peaks were observed for imprinted films at temperatures higher than that for pure nylon, indicating the formation of a more-ordered, hydrogen bonded polymer. Removal of the amino acid from the imprinted film resulted in reversion to the peak observed for pure nylon-6. Additives, β-cyclodextrin and multiwalled carbon nanotubes, were added to the imprinted polymer solutions as a means to increase the porosity of the films. These studies resulted in alternative morphologies and calorimetric results that provide additional functionalities and applications for imprinted polymers.

  20. Poled polymer films for nonlinear optics

    SciTech Connect

    Singer, K.D.; Kuzyk, M.G.; Holland, W.R.; Cahill, P.A.

    1989-01-01

    Second harmonic generation was measured for a thin corona-poled film of a dicyanovinyl azo dye incorporated in the side-chain methacrylate polymer. Measurements were performed at a wavelength of 1.58 ..mu..m as a function of incident angle for both p- and s-polarized incident light. From these measurements the form and magnitude of the second harmonic coefficient tensor were determined. The molecular distribution implied by the data is consistent with a thermodynamic potential containing only the dipolar orienting energy acting during poling. We have also demonstrated anomalous-dispersion phase-matched second harmonic generation for the first time using electric field induced second harmonic generation (EFISH) in a liquid solution of Foron Brilliant Blue S-R (FBB). Results are described. 10 refs., 4 figs., 2 tabs.

  1. Enzyme immobilization on reactive polymer films.

    PubMed

    Cordeiro, Ana L; Pompe, Tilo; Salchert, Katrin; Werner, Carsten

    2011-01-01

    Immobilized enzymes are currently used in many bioanalytical and biomedical applications. This protocol describes the use of thin films of maleic anhydride copolymers to covalently attach enzymes directly to solid supports at defined concentrations. The concentration and activity of the surface-bound enzymes can be tuned over a wide range by adjusting the concentration of enzyme used for immobilization and the physicochemical properties of the polymer platform, as demonstrated here for the proteolytic enzyme Subtilisin A. The versatile method presented allows for the immobilization of biomolecules containing primary amino groups to a broad variety of solid carriers, ranging from silicon oxide surfaces to standard polystyrene well plates and metallic surfaces. The approach can be used to investigate the effects of immobilized enzymes on cell adhesion, and on the catalysis of specific reactions.

  2. Electric conductivity of polymer films filled with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Rumyantsev, B. M.; Bibikov, S. B.; Bychkova, A. V.; Leontiev, V. G.; Berendyaev, V. I.; Sorokina, O. N.; Kovarskii, A. L.

    2016-12-01

    The conductivity of polymer composites with magnetic nanoparticles (MNP) containing magnetite and other MNP (Ni, Cu-Ni) in the layers and planar cells with Al electrodes is studied. For soluble polymers (polyvinylpyrrolidone and polyvinyl alcohol) containing 1-10 wt % of magnetite MNP, a substantial effect of MNP on surface conductivity is detected over a wide range (from 10-10 to 10-3 Ω-1). It is shown that the addition of magnetite MNP not only results in a considerable change in cell conductivity, but also leads to its partially irreversible variation (by an order of magnitude or more) via minor modifications of the experimental conditions (temperature, electric field). For high-resistance samples with low probabilities of conducting chain formation, temperature current peaks are observed upon moderate heating (up to 350 K). These peaks are similar to the maxima observed upon polymer electret thermodischarges when the charges are captured by the deep centers associated with separate MNP or MNP aggregates. The type and position of the maxima are determined by the characteristics of the polymer matrix. For polyvinylpyrrolidone composites, the maxima are observed some time after heating (the echo effect). With composites based on solventborne polymers (polyalkanesterimides, soluble polyimide) and Ni, Cu-Ni MNP, no change in film conductivity measured electrophotographically is observed, due to the formation of a dielectric coating formed by polymer macromolecules adsorbed on the MNP surface. An explanation based on the possible formation of magnetic aggregates of magnetite MNP and conducting chains is proposed. Magnetic aggregation IPM is proposed as one way of controlling cell conductivity.

  3. Optical Properties of Silver Particulate Films on Modified Polymer Substrates

    NASA Astrophysics Data System (ADS)

    Gurumurthy, S. C.; Pattabi, Manjunatha; Sanjeeva, Ganesh

    2011-07-01

    Results of the investigations carried out on the optical properties of particulate films deposited on 8 MeV electron beam irradiated polystyrene (PS) and on blends of PS and Poly (4-vinyl pyridine) (P4VP) are reported. It is observed that absorption maxima shift towards higher wavelength for films deposited on irradiated polystyrene and on blends of PS and P4VP. These results indicate that morphology of the particulate films can be changed by tuning the metal polymer interaction in an inert polymer through electron beam irradiation or by blending it with an interacting polymer like P4VP.

  4. Characterization of polymer films for use in bimorph chemical sensors

    NASA Astrophysics Data System (ADS)

    Chatzandroulis, S.; Goustouridis, D.; Raptis, I.

    2005-01-01

    In the present work white light interferometry is applied for the characterization of polymer films commonly used in bimorph chemical sensors. The study focuses on methacrylate polymers with positive tone patterning capabilities. The behavior upon exposure to controlled concentrations volatile organic compound and water vapors of thin poly (hydroxy ethyl methacrylate) (PHEMA) and poly (methyl methacrylate) (PMMA) layers was evaluated. The normalized film expansion for PHEMA, compared to PMMA, is higher in the case of water and methanol vapors, almost equal for ethanol and significantly lower in the case of acetone. This behavior could be attributed to the combination of polarity and hydrogen bonding capability of the analytes. A wide polymer film thickness range was examined and it was revealed that the normalized film expansion in both PHEMA and PMMA is nearly constant for films thicker than 100 nm and increases for thinner films.

  5. Self-lubricating polymer composites and polymer transfer film lubrication for space applications

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1990-01-01

    The use of self-lubricating polymers and polymer composites in space is somewhat limited today. In general, they are only used when other methods are inadequate. There is potential, however, for these materials to make a significant impact on future space missions if properly utilized. Some of the different polymers and fillers used to make self-lubricating composites are surveyed. The mechanisms of composite lubrication and wear, the theory behind transfer film lubricating mechanisms, and some factors which affect polymer composite wear and transfer are examined. In addition, some of the current space tribology application areas for self-lubricating polymer composites and polymer transfer are mentioned.

  6. Elements of adaptive optics based on metallized polymer films

    NASA Astrophysics Data System (ADS)

    Voliak, T. B.; Krasiuk, I. K.; Pashinin, P. P.

    Results of an experimental study of the stability of metallized polymer films exposed to laser radiation at wavelengths of 1.06 and 10.6 microns are reported, and methods for fabricating variable-curvature mirrors from these films are discussed. Formulas are presented for calculating the shape of film mirrors as a function of the pressure acting on the film, mounting contour, and film properties. The performance of film mirrors is investigated experimentally in a pulsed CO2 laser with stable and unstable resonators.

  7. Development of polymer film solar collectors: A status report

    NASA Astrophysics Data System (ADS)

    Wilhelm, W. G.; Andrews, J. W.

    1982-08-01

    Solar energy collector panels using polymer film and laminate technology were developed which demonstrate low cost and high thermal performance for residential and commercial applications. This device uses common water in the absorber/heat exchanger which is constructed with polymer film adhesively laminated to aluminum foil as the outer surfaces. Stressed polymer films are also used for the outer window and back surface of the panel forming a high strength structural composite. Rigid polymer foam complements the design by contributing insulation and structural definition. This design resulted in very low weight (3.5 kg/m(2)), potentially very low manufacturing cost (aprox. $11/m(2)), and high thermal performance. The development of polymer materials for this technology will be a key to early commercial success.

  8. Dispersing nanoparticles in a polymer film via solvent evaporation

    SciTech Connect

    Cheng, Shengfeng; Grest, Gary S.

    2016-05-19

    Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier to prevent the NPs from moving to the interface. Furthermore, our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.

  9. Dispersing nanoparticles in a polymer film via solvent evaporation

    DOE PAGES

    Cheng, Shengfeng; Grest, Gary S.

    2016-05-19

    Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier tomore » prevent the NPs from moving to the interface. Furthermore, our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.« less

  10. Viewing angle compensation of various LCD modes by using a liquid crystalline polymer film

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takuya; Nishimura, Suzushi

    2013-09-01

    The authors have developed liquid crystalline retardation films to improve certain aspects of LCD image quality such as viewing angle performance and coloration. We have successfully created several types of optical retardation films using a rod-like liquid crystalline polymer. The resulting liquid crystalline polymer films have several advantages over conventional uni- or biaxially stretched retardation films. Precisely controlled structures such as twisted nematic, homogeneous nematic, hybrid nematic and homeotropic structures can provide ideal compensation of various LCD types, such as STN, TN, ECB, VA and IPS-LCDs. Twisted nematic film effectively prevents coloration of STN-LCDs, which is a critical flaw affecting color representation. Short pitch cholesteric film, which utilizes said rod-like liquid crystalline polymer and is the optical equivalent of a negative C-plate, can expand the viewing angle of VA-LCDs. Hybrid nematic film is quite unique in that the film functions not only as a wave plate but also as a viewing angle compensator for TN and ECB-LCDs. Homeotropic film, which acts as a positive-C plate, greatly improves the viewing angle performance of IPS and CPVA-LCDs. Our homeotropically aligned liquid crystalline film, called "NV film", is the world's thinnest retardation film. The thickness of the liquid crystalline layer is a mere 1 micrometer. Homeotropic film can be used to expand the viewing angle not only of LCDs but also OLED displays. And NV film, when used in in combination with a quarter wavelength plate, can expand the viewing angles of the circular polarizers used to prevent reflection in OLED displays.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  12. Hyperbranched polymer films and dendrimers: Their chemistry and applications

    NASA Astrophysics Data System (ADS)

    Zhao, Mingqi

    The research in this dissertation examines the chemistry and applications of dendritic polymers; specifically, hyperbranched polymer thin films and dendrimers. We examined hyperbranched, fluorinated and unfluorinated poly(acrylic acid) (PAA) films on gold substrates, poly(amidoamine) (PAMAM) dendrimer monolayers and dendrimer-alkanethiol mixed monolayers on gold substrates, PAMAM dendrimer/poly(anhydride) and poly(iminopropane-1,3-diyl) (Cascade) dendrimer/poly(anhydride) multilayer films on silicon, gold, and aluminum substrates, PAMAM dendrimer/metal-ion composites, and PAMAM dendrimer-encapsulated metal nanoclusters in solution and on electrode surfaces. Hyperbranched PAA films have pH-dependent blocking abilities: at low pH PAA films effectively passivate Au electrodes while at high pH they are open and permeable. Fluorinated PAA films are far less permeable at any pH. Dendrimers ranging from generation 4 to 8 (G4--G8) can form highly stable and nearly close-packed monolayers and mixed monolayers with hexadecanethiol (C16SH) on surfaces. Moreover, dendrimers embedded within C16SH can act as gates of molecular dimension that control intradendrimer mass transfer of ions. Dendrimer/poly(anhydride) multilayers on surfaces were synthesized and their permeability was investigated. These composite membranes exhibit fully reversible, pH-switchable permselectivity for both cationic and anionic probe molecules because of their pH-dependent electrostatic properties. After heating, such films become highly blocking over the pH range studied due to thermally induced interdendrimer imidization, and other reactions. Finally, we show that PAMAM dendrimers can act first as templates for the preparation of transition-metal nanoclusters, and subsequently as stabilizers. Dendrimers quantitatively complex many transition-metal ions, including Cu 2+, Pt2+, Pd2+, Ru3+, and Ni2+, within their interiors. Chemical reduction of such nanocomposites results in formation of dendrimer

  13. Engineering curvature in graphene ribbons using ultrathin polymer films.

    PubMed

    Li, Chunyu; Koslowski, Marisol; Strachan, Alejandro

    2014-12-10

    We propose a method to induce curvature in graphene nanoribbons in a controlled manner using an ultrathin thermoset polymer in a bimaterial strip setup and test it via molecular dynamics (MD) simulations. Continuum mechanics shows that curvature develops to release the residual stress caused by the chemical and thermal shrinkage of the polymer during processing and that this curvature increases with decreasing film thickness; however, significant deformation is only achieved for ultrathin polymer films. Quite surprisingly, explicit MD simulations of the curing and annealing processes show that the predicted trend not just continues down to film thicknesses of 1-2 nm but that the curvature development is enhanced significantly in such ultrathin films due to surface tension effects. This combination of effects leads to very large curvatures of over 0.14 nm(-1) that can be tuned via film thickness. This provides a new avenue to engineer curvature and, thus, electromagnetic properties of graphene.

  14. Rapid synthesis of flexible conductive polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Blattmann, C. O.; Sotiriou, G. A.; Pratsinis, S. E.

    2015-03-01

    Polymer nanocomposite films with nanoparticle-specific properties are sought out in novel functional materials and miniaturized devices for electronic and biomedical applications. Sensors, capacitors, actuators, displays, circuit boards, solar cells, electromagnetic shields and medical electrodes rely on flexible, electrically conductive layers or films. Scalable synthesis of such nanocomposite films, however, remains a challenge. Here, flame aerosol deposition of metallic nanosliver onto bare or polymer-coated glass substrates followed by polymer spin-coating on them leads to rapid synthesis of flexible, free-standing, electrically conductive nanocomposite films. Their electrical conductivity is determined during their preparation and depends on substrate composition and nanosilver deposition duration. Accordingly, thin (<500 nm) and flexible nanocomposite films are made having conductivity equivalent to metals (e.g. 5 × 104 S cm-1), even during repetitive bending.

  15. Polymer Wall Formation Using Liquid-Crystal/Polymer Phase Separation Induced on Patterned Polyimide Films

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal phase separation of an LC/polystyrene solution between substrates with polyimide films etched by short-wavelength ultraviolet irradiation using a photomask. The LC wetting difference between the polyimide and substrate surfaces caused the coalescence of growing LC droplets on patterned polyimide films with the progress of phase separation. Consequently, polymer walls were formed on substrate surface areas without polyimide films. The shape of the polymer wall formed became sharp with the use of rubbed polyimide films because the nucleation of growing LC droplets concentrated on the patterned polyimide films. It is thought that the increase in the alignment order of LC molecules in the solution near the rubbed polyimide films promotes the formation of LC molecular aggregation, which becomes the growth nuclei of LC droplets.

  16. Stress effects in prism coupling measurements of thin polymer films

    NASA Astrophysics Data System (ADS)

    Agan, S.; Ay, F.; Kocabas, A.; Aydinli, A.

    2005-02-01

    Due to the increasingly important role of some polymers in optical waveguide technologies, precise measurement of their optical properties has become important. Typically, prism coupling to slab waveguides made of materials of interest is used to measure the relevant optical parameters. However, such measurements are often complicated by the softness of the polymer films when stress is applied to the prism to couple light into the waveguides. In this work, we have investigated the optical properties of three different polymers, polystyrene (PS), polymethyl-methacrylate (PMMA), and benzocyclobutane (BCB). For the first time, the dependence of the refractive index, film thickness, and birefringence on applied stress in these thin polymer films was determined by means of the prism coupling technique. Both symmetric trapezoid shaped and right-angle prisms were used to couple the light into the waveguides. It was found that trapezoid shaped prism coupling gives better results in these thin polymer films. The refractive index of PMMA was found to be in the range of 1.4869 up to 1.4876 for both TE and TM polarizations under the applied force, which causes a small decrease in the film thickness of up to 0.06 μm. PMMA waveguide films were found not to be birefringent. In contrast, both BCB and PS films exhibit birefringence albeit of opposing signs.

  17. Water Vapor Permeation of Metal Oxide/Polymer Coated Plastic Films

    NASA Astrophysics Data System (ADS)

    Numata, Yukihiro; Oya, Toshiyuki; Kuwahara, Mitsuru; Ito, Katsuya

    Barrier performance to water vapor permeation of ceramic coated layers deposited on flexible polymer films is of great interest to food packaging, medical device packaging and flat panel display industries. In this study, a new type film in which a ceramic layer is deposited on a polymer coated film was proposed for lower water vapor permeation. It is important how to control interfacial properties between each layer and film for good barrier performance. Several kinds of polymer coated materials were prepared for changing surface free energy of the films before and after depositing the ceramic layer. The ceramic layer, which is composed of mixed material of SiO2 and Al2O3, was adopted under the same conditions. The following results were obtained; 1) Water vapor permeation is not related to the surface energy of polymer coated films, 2) After depositing the ceramic layer, however, a strong correlation is observed between the water vapor permeation and surface free energy. 3) The phenomenon is considered that the polarity of the polymer layers plays a key role in changing the structure of ceramic coated layers.

  18. Adhesion of metals to spin-coated fluorocarbon polymer films

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Kil; Chang, Chin-An; Schrott, A. G.

    1990-01-01

    Adhesion between metals and fluorocarbon polymer films has been studied for Cu, Cr, Ti, Al, and Au on polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films. Polymer films were applied on the Cr/SiO2 /Si substrate by spinning the aqueous dispersions of the polymer resin particles, followed by thermal curing. Strips of different metals were deposited on the polymers, and adhesion was measured at 90° peel test. The peel strengths were invariably higher for the metals on FEP than those of the corresponding metals on PTFE. Among the metals, Ti showed the highest peel strength for both polymers, followed by Cr and Al, with Cu and Au being the lowest. The peel strengths of Ti, Cr, and Cu on FEP are 85, 45, and 12 g/mm, respectively, and the corresponding ones on PTFE are 23, 5, and 2 g/mm, respectively. X-ray photoelectron spectroscopic analysis shows that the metal-polymer bonding involves the metal-carbon interactions. The strongest interaction is observed for Ti with the polymers, forming Ti carbidelike bonds. Cr also shows strong interaction with the two polymers, but to a lesser degree compared with Ti. Only a weak bonding is shown for Cu. The difference in peel strengths among the metals shows a correlation with the difference in electronegativities between the metals and carbon. Little contribution to the observed peel strengths is seen from the surface morphological analysis of the untreated polymers.

  19. Fracture and fatigue of ultrathin nanoporous polymer films

    NASA Astrophysics Data System (ADS)

    Kearney, Andrew V.

    Nanoporous polymer layers are being considered for a range of emerging nanoscale applications, from low permittivity materials for interlayer dielectrics in microelectronics and anti-reflective coatings in optical technologies, to biosensors and size-selective membranes for biological applications. Polymer thin films have inherently low elastic modulus, strength and hardness, but exhibit fracture properties that are higher than those reported for glass, ceramic, and even some metal layers. However, constraint of a ductile polymer between two elastic layers is expected to affect the local plasticity ahead of a crack tip and its contribution to the film adhesion with films below a micron in thickness. Additionally, nanoporosity would be expected to have a deleterious effect on mechanical properties, producing materials and layers that are structurally weaker than fully dense versions they replace. Therefore, the integration of these nanoporous polymer layer at nanometer thicknesses would present significantly processing and mechanical reliability challenges. In this dissertation, surprising evidence is presented that nanoporous polymer films exhibit increasing fracture energy with increasing porosity. Such behavior is in stark contrast to a wide range of reported behavior for porous solids. A ductile nano-void growth and coalescence fracture mechanics-based model is presented to rationalize the increase in fracture toughness of the voided polymer film. The model is shown to explain the behavior in terms of a specific scaling of the size of the pores with pore volume fraction. It is demonstrated that the pore size must increase with close to a linear dependence on the volume fraction in order to increase rather than decrease the fracture energy. Independent characterization of the pore size as a function of volume fraction is shown to confirm predictions made by the model. The fracture behavior of these constrained polymer films are also examined with film thickness

  20. Special Polymer/Carbon Composite Films for Detecting SO2

    NASA Technical Reports Server (NTRS)

    Homer, Margie; Ryan, Margaret; Yen, Shiao-Pin; Kisor, Adam; Jewell, April; Shevade, Abhijit; Manatt, Kenneth; Taylor, Charles; Blanco, Mario; Goddard, William

    2008-01-01

    A family of polymer/carbon films has been developed for use as sensory films in electronic noses for detecting SO2 gas at concentrations as low as 1 part per million (ppm). Most previously reported SO2 sensors cannot detect SO2 at concentrations below tens of ppm; only a few can detect SO2 at 1 ppm. Most of the sensory materials used in those sensors (especially inorganic ones that include solid oxide electrolytes, metal oxides, and cadmium sulfide) must be used under relatively harsh conditions that include operation and regeneration at temperatures greater than 100 C. In contrast, the present films can be used to detect 1 ppm of SO2 at typical opening temperatures between 28 and 32 C and can be regenerated at temperatures between 36 and 40 C. The basic concept of making sensing films from polymer/carbon composites is not new. The novelty of the present family of polymer/carbon composites lies in formulating the polymer components of these composites specifically to optimize their properties for detecting SO2. First-principles quantum-mechanical calculations of the energies of binding of SO2 molecules to various polymer functionalities are used as a guide for selecting polymers and understanding the role of polymer functionalities in sensing. The polymer used in the polymer-carbon composite is a copolymer of styrene derivative units with vinyl pyridine or substituted vinyl pyridine derivative units. To make a substituted vinyl pyridine for use in synthesizing such a polymer, poly(2-vinyl pyridine) that has been dissolved in methanol is reacted with 3-chloropropylamine that has been dissolved in a solution of methanol. The methanol is then removed to obtain the copolymer. Later, the copolymer can be dissolved in an appropriate solvent with a suspension of carbon black to obtain a mixture that can be cast and then dried to obtain a sensory film.

  1. Phase separation of polymer thin films and some applications

    NASA Astrophysics Data System (ADS)

    Zhu, Shaoming

    Phase separation of polymer thin film is a common issue in polymer thin film application. The existence of surface and surfactant are understood to play an important role in thin film final topography. In chapter two, the configuration of polymer blend thin film phase separation on cobalt substrate with PMMA phase forming column structure, and PS phase encapsulating the PMMA phase was used as resist mask to transfer the topographical feature to cobalt thin film. Isolated near spherical single and multi domain magnetic islands were obtained. The island made using this method had a broad single domain range from below 1000 to 5000A. In chapter three, when the polymer blend thin film was in bilayer configuration and diblock copolymer was added on the top layer, we found the confinement can increase the mixing of two homopolymers in highly incompatible polymer blends. By affecting the formation of micelles, the copolymers are forced to the interface between the two homopolymer phases where they reduce the interfacial tension to zero and form a microemulsion. Our findings have two important implications: first, they elucidate the role entropy plays in determining the phase behaviour of confined polymer blends and second, they offer a simple pathway to create thin film coatings with precisely controlled properties and surfaces. In chapter four, the kinetics process of microemulsion formation in confinement configuration has been analyzed. The microemulsion formation proceeded at initial stage by capillary wave, then it followed the growth regime t1/3 and lnt, then followed a more slow growth regime (lnt).56 or (lnt).60 till finally reached equilibrium, when the structure was frozen. In chapter five, we study the evolution of the morphologies of polymer blend thin films on silicon, cobalt, and gold substrates. In asymmetrical system, the substrate surface energy determined the wetting degree of the substrate preferring phases. In chapter six, we present a novel method for

  2. The electrocaloric efficiency of ceramic and polymer films.

    PubMed

    Defay, Emmanuel; Crossley, Sam; Kar-Narayan, Sohini; Moya, Xavier; Mathur, Neil D

    2013-06-25

    Efficiency is defined as η = |Q|/|W| in order to investigate the electrical work |W| associated with electrocaloric heat |Q|. This materials parameter indicates that polymer films are slightly more energy efficient than ceramic films, and therefore both species of material remain candidates for future cooling applications.

  3. 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.

  4. Film formation and mechanical behavior of polymer latexes

    SciTech Connect

    Gauthier, C.; Sindt, O.; Perez, J.

    1995-12-31

    The purpose of this lecture is to review the present state of the art in the field of film formation in relation with the mechanical behavior of polymer films. After a review of the theoretical approaches concerning film forming process, we show the influence of some experimental parameters (temperature, hygrometry {hor_ellipsis}) in the case of a core-shell latex obtained from polystyrene/Poly (Styrene co. butyl acrylate). Then, the mechanical behavior of polymer films is considered. The improvement of the mechanical strength of latex films during the last stage of film formation (i.e., gradual coalescence) is illustrated. Further analysis of the molecular process yielding mechanical behavior allows us to show how the comparison between prediction and experimental data can provide information on morphological changes, on the stability of this one, or on the formation of an interphase between constituting phases.

  5. Polymer fullerene solution phase behaviour and film formation pathways.

    PubMed

    Dattani, Rajeev; Cabral, João T

    2015-04-28

    We report the phase behaviour of polymer/fullerene/solvent ternary mixtures and its consequence for the morphology of the resulting composite thin films. We focus particularly on solutions of polystyrene (PS), C60 fullerene and toluene, which are examined by static and dynamic light scattering, and films obtained from various solution ages and thermal annealing conditions, using atomic force and light microscopy. Unexpectedly, the solution phase behaviour below the polymer overlap concentration, c*, is found to be described by a simple excluded volume argument (occupied by the polymer chains) and the neat C60/solvent miscibility. Scaling consistent with full exclusion is found when the miscibility of the fullerene in the solvent is much lower than that of the polymer, giving way to partial exclusion with more soluble fullerenes (phenyl-C61-butyric acid methyl ester, PCBM) and a less asymmetric solvent (chlorobenzene), employed in photovoltaic devices. Spun cast and drop cast films were prepared from PS/C60/toluene solutions across the phase diagram to yield an identical PS/C60 composition and film thickness, resulting in qualitatively different morphologies in agreement with our measured solution phase boundaries. Our findings are relevant to the solution processing of polymer/fullerene composites (including organic photovoltaic devices), which generally require effective solubilisation of fullerene derivatives and polymer pairs in this concentration range, and the design of well-defined thin film morphologies.

  6. Structural Changes in Polymer Films by Fast Ion Implantation

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; Minamisawa, R. A.; Muntele, C.; Muntele, I.; De Almeida, A.; Ila, D.

    2006-11-01

    In applications from food wrapping to solar sails, polymers films can be subjected to intense charged panicle bombardment and implantation. ETFE (ethylenetetrafluoroethylene) with high impact resistance is used for pumps, valves, tie wraps, and electrical components. PFA (tetrafluoroethylene-per-fluoromethoxyethylene) and FEP (tetrafluoroethylene-hexa-fluoropropylene) are sufficiently biocompatible to be used as transcutaneous implants since they resist damage from the ionizing space radiation, they can be used in aerospace engineering applications. PVDC (polyvinyllidene-chloride) is used for food packaging, and combined with others plastics, improves the oxygen barrier responsible for the food preservation. Fluoropolymers are also known for their radiation dosimetry applications, dependent on the type and energy of the radiation, as well as of the beam intensity. In this work ETFE, PFA, FEP and PVDC were irradiated with ions of keV and MeV energies at several fluences and were analyzed through techniques as RGA, OAP, FTIR, ATR and Raman spectrophotometry. CF3 is the main specie emitted from PFA and FEP when irradiated with MeV protons. H and HF are released from ETFE due to the broken C-F and C-H bonds when the polymer is irradiated with keV Nitrogen ions and protons. At high fluence, especially for keV Si and N, damage due to carbonization is observed with the formation of hydroperoxide and polymer dehydroflorination. The main broken bonds in PVDC are C-O and C-Cl, with the release of Cl and the formation of double carbon bonds. The ion fluence that causes damage, which could compromise fluoropolymer film applications, has been determined.

  7. Microporous polymer films and methods of their production

    DOEpatents

    Aubert, J.H.

    1995-06-06

    A process is described for producing thin microporous polymeric films for a variety of uses. The process utilizes a dense gas (liquefied gas or supercritical fluid) selected to combine with a solvent-containing polymeric film so that the solvent is dissolved in the dense gas, the polymer is substantially insoluble in the dense gas, and two phases are formed. A microporous film is obtained by removal of a dense gas-solvent phase. 9 figs.

  8. Microporous polymer films and methods of their production

    DOEpatents

    Aubert, James H.

    1995-01-01

    A process for producing thin microporous polymeric films for a variety of uses. The process utilizes a dense gas (liquified gas or supercritical fluid) selected to combine with a solvent-containing polymeric film so that the solvent is dissolved in the dense gas, the polymer is substantially insoluble in the dense gas, and two phases are formed. A microporous film is obtained by removal of a dense gas-solvent phase.

  9. Polymer functionalized n-type single wall carbon nanotube photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Li, Zhongrui; Saini, Viney; Dervishi, Enkeleda; Kunets, Vasyl P.; Zhang, Jianhui; Xu, Yang; Biris, Alexandru R.; Salamo, Gregory J.; Biris, Alexandru S.

    2010-01-01

    Photovoltaic conversion was achieved from high-density p-n heterojunctions formed between polymer functionalized n-type single wall carbon nanotubes (SWNTs) and underlying p-type Si substrate. Functionalization of SWNTs by amine-rich polymers results in the evolution of tubes from p-type to n-type, and the polyethylene imine (PEI) functionalized SWNT film can serve as both photogeneration sites and a charge carrier collecting/transport layer. Photoremoval of oxygen adsorbed on the nanotubes prior to PEI functionalization can increase the conversion efficiency of the polymer functionalized n-type SWNT photovoltaic devices.

  10. 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.

  11. Deviations from liquidlike behavior in molten polymer films at interfaces.

    PubMed

    Seo, Young-Soo; Koga, T; Sokolov, J; Rafailovich, M H; Tolan, M; Sinha, S

    2005-04-22

    We have performed x-ray specular and diffuse scattering on liquid polymer films and analyzed the spectra as a function of film thickness and molecular weight. The results show that films whose molecular weight is close to the entanglement length behave as simple liquids except that the shortest wavelength is determined by the radius of gyration (R(g)) rather than the monomer-monomer distance. When the molecular weight is higher than the entanglement length, the strong deviations from liquidlike behavior are observed. We find that the long wavelength cutoff vector, q(l,c), scales with film thickness, d as d(-1.1+/-0.1) rather than the usual d(-2) expected for simple liquids. If we assume that these deviations are due to surface pinning of the polymer chains, then our results are consistent with the formalism developed by Fredrickson et al. to explain the capillary wave spectrum that can propagate in a polymer brush.

  12. Directed Morphology of Nanofilled Polymer Films on Flexible Substrates

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Diya; Hayirlioglu, Arzu; Kulkarni, Manish; Karim, Alamgir

    2011-03-01

    We demonstrate viable meso-patterning techniques that have relevance to electronics and organic photovoltaic applications via tunable control of polymer thin film instabilities. To this end, we examine the influence of fullerene (C60) nanoparticles on multicomponent polymer thin films on patterned and flexible polydimethylsiloxane substrates and compare these results to morphologies on hard silica xerogel substrates of variable roughness and surface energy. Controlled incorporation of nanoparticles (NPs) can be used to tune polymer thin film instabilities and morphology. At NP concentrations below a threshold value, we observe directed dewetting of blend thin films consisting of uniformly aligned dewet domains that mimic the periodicity of the confining media, consistent with our previous experiments where it was observed that C60 NPs preferentially segregate to a PS/PB blend interface up to a certain saturation concentration.

  13. Vacuum deposited polymer/metal films for optical applications

    NASA Astrophysics Data System (ADS)

    Affinito, J. D.; Martin, P. M.; Gross, M. E.; Coronado, C.; Greenwell, E.

    1995-04-01

    Vacuum deposited Polymer/Silver/Polymer reflectors and Tantalum/Polymer/Aluminum Fabry-Perot interference filters were fabricated in a vacuun web coating operation on polyester substrates with a new, high speed deposition process. Reflectivities were measured in the wavelength range from 0.3 to 0.8(mu)m. This new vacuum processing technique has been shown to be capable of deposition line speeds in excess of 500 linear meters/minute. Central to this technique is a new position process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process -- for Polymer Multi-Layer. Also, vacuum deposited, index matched, polymer/CaF(sub 2) composites were fabricated from monomer slurries that were subsequently cured with LTV light. This second technique is called the Liquid Multi-Layer (or LML) process. Each of these polymer processes is compatible with each other and with conventional vacuum deposition processes such as sputtering or evaporation.

  14. Numerical solutions of thin-film equations for polymer flows.

    PubMed

    Salez, Thomas; McGraw, Joshua D; Cormier, Sara L; Bäumchen, Oliver; Dalnoki-Veress, Kari; Raphaël, Elie

    2012-11-01

    We report on the numerical implementation of thin-film equations that describe the capillary-driven evolution of viscous films, in two-dimensional configurations. After recalling the general forms and features of these equations, we focus on two particular cases inspired by experiments: the leveling of a step at the free surface of a polymer film, and the leveling of a polymer droplet over an identical film. In each case, we first discuss the long-term self-similar regime reached by the numerical solution before comparing it to the experimental profile. The agreement between theory and experiment is excellent, thus providing a versatile probe for nanorheology of viscous liquids in thin-film geometries.

  15. Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

    2002-01-01

    Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

  16. Patterning Multicomponent Polymer Thin Films via Dynamic Thermal Processing

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet

    Bottom-up patterning is gaining increased importance owing to the physical limitations and rising costs of top-down patterning. One example of bottom-up patterning is self-assembling polymer thin films. Although there are several pathways to facilitate polymer thin film self-assembly, this presentation will focus on dynamic thermal field based processes for patterning multicomponent polymer thin films. Dynamic thermal field processing is an attractive roll­to­roll (R2R) amenable directed self­assembly (DSA) method for molecular level organization of multicomponent polymer systems such as block copolymer thin films over large areas without requiring guiding templates. The talk will first outline how parameters such as magnitude of the temperature gradient, velocity of annealing, thermal expansion, and molecular weight of the polymer can be optimized to finely tune the morphology of the block copolymer thin films and also elucidate their associated physical mechanisms. The second part of the talk will outline application of dynamic thermal field processes for fabricating functional nanomaterials and discuss the recent advancements achieved using these processes.

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

    PubMed

    Freed, Karl F

    2015-04-07

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

  18. Lattice cluster theory for dense, thin polymer films

    SciTech Connect

    Freed, Karl F.

    2015-04-07

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

  19. Effect of surfactant type and redox polymer type on single-walled carbon nanotube modified electrodes.

    PubMed

    Chen, Jie; Tran, Tu O; Ray, Michael T; Brunski, Daniel B; Keay, Joel C; Hickey, David; Johnson, Matthew B; Glatzhofer, Daniel T; Schmidtke, David W

    2013-08-20

    Electrodes modified with single-walled carbon nanotubes (SWNTs) offer a number of attractive properties for developing novel electrochemical sensors. A common method to immobilize SWNTs onto the electrode surface is by placing a droplet of a SWNT suspension onto the electrode surface and allowing the solvent to evaporate. In order to maximize the properties of individual SWNTs, surfactants are normally present in these suspensions to provide stable and homogeneous SWNT dispersions. In this study we investigated the effect of different surfactants on the electrochemical and enzymatic performance of SWNT modified glassy carbon electrodes (GCEs). Amperometic biosensors for glucose were fabricated by a two-step procedure. In the first step, SWNT films were deposited onto GCEs by solution casting suspensions of SWNTs in water, Triton X-100, Tween 20, sodium cholate or sodium dodecylbenzenesulfonate (NaDDBS). In the second step, hydrogels containing a redox polymer and the enzyme, glucose oxidase (GOX), were deposited and cross-linked onto the SWNT-modified GCE. Three different redox polymers were tested: 3-ferrocenylpropyl-modified LPEI, (Fc-C3-LPEI), 6-ferrocenylhexyl-modified LPEI, (Fc-C6-LPEI), and poly[(vinylpyridine)Os(bipyridyl)2Cl](2+/3+)(PVP-Os). Biosensors constructed with SWNT films from suspensions of Triton X-100 or Tween 20 generally produced the highest electrochemical and enzymatic responses, with Triton X-100 films producing current densities of ~1.7-2.1 mA/cm(2) for the three different redox polymers. In contrast, biosensors constructed with SWNT films from sodium cholate suspensions resulted in significant decreases in the electrochemical and enzymatic response and in some cases showed no enzymatic activity. The results with SWNT films from NaDDBS suspensions were dependent upon the specific redox polymer used, but in general gave reduced enzymatic responses (~0.05-0.4 mA/cm(2)). These results demonstrate the importance of surfactant type in

  20. Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

    PubMed

    Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

    2013-06-26

    The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

  1. Pattern formation and evolution in thin polymer films

    NASA Astrophysics Data System (ADS)

    Masson, Jean-Loup Didier

    2001-07-01

    Thin polymer films are important for many technologies. They are used as coatings, adhesives, lubricants and for device technologies, such as polymer based light-emitting diodes. Several concerns arise when processing and using thin polymer films. Properties of thin polymer films (e.g., viscosity, diffusion, glass transition temperature) are different from bulk properties due to finite size effects (e.g., confinement of the chains) and to interfacial interactions (e.g., presence of the free surface and the substrate). Moreover, the stability of the film on the substrate is of concern. Thin polymer films, of thickness h < 100 nm, fabricated on a substrate may rupture under destabilizing forces, such as van der Waals forces. Rupturing exposes the underlying substrate and the exposed regions will grow, provided that the spreading coefficient is negative. This process is known as dewetting. Thus far, two dewetting morphologies have been identified but little is understood about their formation and evolution. The first morphology consists of circular holes throughout the film and the second morphology is reminiscent of patterns associated with spinodal decomposition processes. In this research, we investigated four problems. First, we examined fundamental questions related to the formation and evolution of patterns on the substrate. We documented the existence of different dynamic stages of evolution associated with different driving forces for both "conventional" morphologies (circular holes and "spinodal-like"). Second, we discovered a new morphology that occurs in a thin random copolymer film on a silicon substrate. This morphology results from heterogeneous interactions of the chain segments with the substrate. Third, we examined flow processes in thin polymer films (chain dynamics near surfaces). We show that a fingering instability develop spontaneously at the moving liquid front when the film is below a critical thickness that depends on the length of the chains

  2. Influence of substrate and film thickness on polymer LIPSS formation

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Nogales, Aurora; Ezquerra, Tiberio A.; Rebollar, Esther

    2017-02-01

    Here we focus on the influence of both, substrate and film thickness on polymer Laser Induced Periodic Surface Structures (LIPSS) formation in polymer films. For this aim a morphological description of ripples structures generated on spin-coated polystyrene (PS) films by a linearly polarized laser beam with a wavelength of 266 nm is presented. The influence of different parameters on the quality and characteristics of the formed laser-induced periodic surface structures (LIPSS) was investigated. We found that well-ordered LIPSS are formed either on PS films thinner than 200 nm or thicker than 400 nm supported on silicon substrates as well as on thicker free standing films. However less-ordered ripples are formed on silicon supported films with intermediate thicknesses in the range of 200-380 nm. The effect of the thermal and optical properties of the substrate on the quality of LIPSS was analyzed. Differences observed in the fluence and number of pulses needed for the onset of surface morphological modifications is explained considering two main effects which are: (1) The temperature increase on polymer surface induced by the action of cumulative laser irradiation and (2) The differences in thermal conductivity between the polymer and the substrate which strongly affect the heat dissipation generated by irradiation.

  3. Detecting Airborne Mercury by Use of Polymer/Carbon Films

    NASA Technical Reports Server (NTRS)

    Shevade, Abhijit; Ryan, Margaret; Homer, Margie; Kisor, Adam; Jewell, April; Yen, Shiao-Pin; Manatt, Kenneth; Blanco, Mario; Goddard, William

    2009-01-01

    Films made of certain polymer/carbon composites have been found to be potentially useful as sensing films for detecting airborne elemental mercury at concentrations on the order of tens of parts per billion or more. That is to say, when the polymer/carbon composite films are exposed to air containing mercury vapor, their electrical resistances decrease by measurable amounts. Because airborne mercury is a health hazard, it is desirable to detect it with great sensitivity, especially in enclosed environments in which there is a risk of a mercury leak from lamps or other equipment. The present effort to develop polymerbased mercury-vapor sensors complements the work reported in NASA Tech Briefs Detecting Airborne Mercury by Use of Palladium Chloride (NPO- 44955), Vol. 33, No. 7 (July 2009), page 48 and De tecting Airborne Mer cury by Use of Gold Nanowires (NPO-44787), Vol. 33, No. 7 (July 2009), page 49. Like those previously reported efforts, the present effort is motivated partly by a need to enable operation and/or regeneration of sensors under relatively mild conditions more specifically, at temperatures closer to room temperature than to the elevated temperatures (greater than 100 C ) needed for regeneration of sensors based on noble-metal films. The present polymer/carbon films are made from two polymers, denoted EYN1 and EYN2 (see Figure 1), both of which are derivatives of poly-4-vinyl pyridine with amine functional groups. Composites of these polymers with 10 to 15 weight percent of carbon were prepared and solution-deposited onto the JPL ElectronicNose sensor substrates for testing. Preliminary test results showed that the resulting sensor films gave measurable indications of airborne mercury at concentrations on the order of tens of parts per billion (ppb) or more. The operating temperature range for the sensing films was 28 to 40 C and that the sensor films regenerated spontaneously, without heating above operating temperature (see Figure 2).

  4. Molecular modeling of responsive polymer films

    SciTech Connect

    Tagliazucchi, Mario; Calvo, Ernesto J; Szleifer, Igal

    2010-06-29

    In this perspective, we have shown three different cases of responsive polymers at surfaces where the properties of the surface can be varied in response to cues from the bulk solution or in the presence of an external field. The most important conclusion in all three cases is that the chemical reaction equilibrium, physical interactions and molecular organization are strongly coupled, and it is imperative to consider the global and local changes that occur to the surface structure and properties due to this coupling. In particular acid-base and redox equilibrium are very different in polymer-modified surfaces than in the corresponding bulk solutions. Moreover, the definition of ‘‘apparent redox potentials’’ and ‘‘apparent pKa’’results from the averaging over highly inhomogeneous values,and, therefore, they do not necessarily represent the state of the layer and the local values and their variation are very important for the design of functional surfaces. The very large variation on chemical equilibrium results from the optimization of all the interactions. The picture that emerges is that trying to deduce what the final state of the system is by looking at the individual optimization of each contribution leads to qualitative incorrect assumptions and only the minimization of the complete free energy leads to the proper behavior in these complex systems.In the cases where domain formation is possible in grafted weak polyacid layers charge regulation may lead to regimes of coexistence between aggregates with relatively low fraction of charged polymer segments surrounded by highly stretched chains that have a relatively high fraction of charged groups.Therefore, one can control the state of charge, local electrostatic potential and local pH in all three dimensions with im-portant gradients on length scales of nanometers. For hydrophobic redox polymers we show how the application of an electrode potential can lead to changes in the structure

  5. Integrated optical components in thin films of polymers

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey; Abdeldayem, Hossin; Venkateswarlu, Putcha; Teague, Zedric

    1995-01-01

    The results will be reported on the study of integrated optical components based on nonlinear optical polymeric films. Polymers poly(methyl methacrylate) (PMMA) and polyimide (PI) doped with organic laser dyes 4-dicyanomethylene-2-methyl-6-p dimethylaminostyryl-4H pyran (DCM) and 1, 3, 5, 7, 8 - pentamethyl-2,6 -diethyl-pyrromethene -BF2-complex (Pyrommethene 567, PM-567) were selected as materials for light guiding films. Additionally, UV polymerized polydiacetylene (PDA) on glass substrate was used as a waveguide material. Optical waveguides were fabricated using spin coating of preoxidized silicon wafers (1.5 micrometer silicon oxide layer) with organic dye/polymer solution followed by soft baking. the modes in slab waveguides were studied using prism coupling techniques. Measured values of mode coupling angles in multimode waveguides were used to calculate film thickness and refractive index for different polarizations. Refractive index anisotropy was found in PDA waveguide. The optimal conditions of spin coating for single mode waveguide fabrication were estimated. Propagation losses were measured by collecting the light scattered from the trace of a propagating mode either by scanning photo detector or by CCD camera. Different types of light coupling techniques were used including end-dire coupling, prism and grating coupling. Mechanical printing technique was developed for coupling grating fabrication resulting in gratings with 4% diffraction efficiency. The gratings demonstrated good stability with diffraction efficiency relaxation rate 2.4 dB/hour at a temperature approximately 15-20 C below glass transition point. Dye doped waveguides were transversally pumped with frequency doubled Nd:YAG Q-switched laser producing intensive light emission with apparent 6 kW/sq cm pump threshold and spectrum narrowing near 617 nm peak in the case of DCM doped waveguide. PM-567 doped waveguide pumped with CW Ar(+) laser (514 nm wavelength) far below threshold (0.1 W

  6. Dry-film polymer waveguide for silicon photonics chip packaging.

    PubMed

    Hsu, Hsiang-Han; Nakagawa, Shigeru

    2014-09-22

    Polymer waveguide made by dry film process is demonstrated for silicon photonics chip packaging. With 8 μm × 11.5 μm core waveguide, little penalty is observed up to 25 Gbps before or after the light propagate through a 10-km long single-mode fiber (SMF). Coupling loss to SMF is 0.24 dB and 1.31 dB at the polymer waveguide input and output ends, respectively. Alignment tolerance for 0.5 dB loss increase is +/- 1.0 μm along both vertical and horizontal directions for the coupling from the polymer waveguide to SMF. The dry-film polymer waveguide demonstrates promising performance for silicon photonics chip packaging used in next generation optical multi-chip module.

  7. Design, synthesis, and characterization of ladder-type molecules and polymers. Air-stable, solution-processable n-channel and ambipolar semiconductors for thin-film transistors via experiment and theory.

    PubMed

    Usta, Hakan; Risko, Chad; Wang, Zhiming; Huang, Hui; Deliomeroglu, Murat K; Zhukhovitskiy, Aleksandr; Facchetti, Antonio; Marks, Tobin J

    2009-04-22

    The design, synthesis, and characterization of new high-performance n-channel molecular/polymeric semiconductors that are solution-processable and air-stable is of great interest for the development of p-n junctions, bipolar transistors, and organic complementary circuitry (CMOS). While over the past two decades there have been many reports on n-channel materials, solution-processability and air-stability still remain as major challenges. We report here the synthesis and detailed characterization of a highly electron-deficient class of indeno[1,2-b]fluorene-6,12-dione, 2,2'-(indeno[1,2-b]fluorene-6,12-diylidene) dimalononitrile, bisindenofluorene-12,15-dione, and 2,2'-(bisindenofluorene-12,15-diylidene) dimalononitrile-based ladder-type building blocks (1-12) and their corresponding homo- and copolymers (P1-P14), and examine in detail the effects of core size, thiophene vs core regiochemistry, carbonyl vs dicyanovinylene functionality, and alkyl chain orientation on the physicochemical properties, thin film microstructures, and OFET device performance. New compounds are characterized by DSC, TGA, melting point, single-crystal X-ray diffraction (XRD), solution/thin film optical, PL, and cyclic voltammetry measurements to evaluate frontier molecular orbital energetics and intermolecular cohesive forces. Thin films are grown by vacuum deposition and spin-coating, and investigated by X-ray diffraction (XRD) and AFM. By tuning the HOMO/LUMO energetics of the present materials over a 1.1 eV range, p-type, n-type, or ambipolar charge transport characteristics can be observed, thus identifying the MO energetic windows governing majority carrier polarity and air stability. One of these systems, thiophene-terminated indenofluorenedicyanovinylene 10 exhibits an electron mobility of 0.16 cm(2)/V x s and an I(on)/I(off) ratio of 10(7)-10(8), one of the highest to date for a solution-cast air-stable n-channel semiconductor. Here we also report solution-processed ambipolar films

  8. Spinodal Clustering in Thin Films of Nanoparticle-Polymer Mixtures

    NASA Astrophysics Data System (ADS)

    Wong, Him Cheng; Cabral, João T.

    2010-07-01

    Thin supported polystyrene-C60 fullerene mixtures annealed above their glass transition temperature develop spinodal surface undulations which depend on film thickness h(20-500nm), polymer molecular mass Mw, temperature, and time t. The dominant wavelength λ˜1-10μm scales linearly with h and coarsening kinetics follow λ˜tα, with 0<α(h)<1/3; the morphology eventually pins at long times. This spinodal surface excitation contrasts with dewetting suppression and film stability observed in low-Mw polymers and results from the interplay of binary miscibility and fullerene substrate attraction.

  9. Nanostructure investigation of polymer solutions, polymer gels, and polymer thin films

    NASA Astrophysics Data System (ADS)

    Lee, Wonjoo

    This thesis discusses two systems. One is structured hydrogels which are hydrogel systems based on crosslinked poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA) containing micelles which form nanoscale pores within the PDMAEMA hydrogel. The other is nanoporous block copolymer thin films where solvent selectivity is exploited to create nanopores in PS-b-P4VP thin films. Both of these are multicomponent polymer systems which have nanoscale porous structures. 1. Small angle neutron scattering of micellization of anionic surfactants in water, polymer solutions and hydrogels. Nanoporous materials have been broadly investigated due to the potential for a wide range of applications, including nano-reactors, low-K materials, and membranes. Among those, molecularly imprinted polymers (MIP) have attracted a large amount of interest because these materials resemble the "lock and key" paradigm of enzymes. MIPs are created by crosslinking either polymers or monomers in the presence of template molecules, usually in water. Initially, functional groups on the polymer or the monomer are bound either covalently or noncovalently to the template, and crosslinking results in a highly crosslinked hydrogel. The MIPs containing templates are immersed in a solvent (usually water), and the large difference in the osmotic pressure between the hydrogel and solvent removes the template molecules from the MIP, leaving pores in the polymer network containing functionalized groups. A broad range of different templates have been used ranging from molecules to nanoscale structures inclucing stereoisomers, virus, and micelles. When micelles are used as templates, the size and shape before and after crosslinking is an important variable as micelles are thermodynamic objects whose structure depends on the surfactant concentration of the solution, temperature, electrolyte concentration and polymer concentration. In our research, the first goal is to understand the micellization of anionic

  10. Reversible thermochromic polymer film embedded with fluorescent organogel nanofibers.

    PubMed

    Kim, Hyungwoo; Chang, Ji Young

    2014-11-18

    We report a reversible thermochromic nanocomposite polymer film composed of fluorescent organogel fibers and a highly cross-linked polymer matrix. A series of cyano-substituted oligo(p-phenylenevinylene) (CN-OPV) derivatives were synthesized by the reaction of dialdehydes with phenyl or naphthyl acetonitrile under basic conditions. Among the CN-OPV derivatives, NA-DBA having naphtyl moieties and dodecyloxy chains formed a stable organogel in a cross-linkable monomeric solvent (ethylene glycol dimethacrylate). The organogel showed a thermoreversible sol-gel transition, accompanying the emission color change. A nanocomposite polymer film obtained by photopolymerization of the organogel between two quartz plates also exhibited reversible thermochromism. Under 365 nm irradiation, the orange color of the film at 25 °C became yellowish green at 120 °C. The fluorescence spectroscopy, DSC, and microscopy results determined that the thermally reversible self-assembly of NA-DBA occurred in the polymer matrix, resulting in reversible thermochromism. The melted gelator molecules at 120 °C did not diffuse into the polymer matrix probably because of poor interactions of the gelator molecules with the polymer matrix. The NA-DBA molecules dispersed in poly(methyl methacrylate), without forming a supramolecular structure, did not show thermochromism.

  11. Probing nano-rheology in thin polymer films

    NASA Astrophysics Data System (ADS)

    Dalnoki-Veress, Kari

    2013-03-01

    In this talk I will summarize our recent work on using stepped films to uncover some of the physics relevant to polymer rheology on length scales comparable to the size of polymer molecules. The work presented will focus on the efforts of a larger collaboration (Elie Raphael's theory group in Paris and James Forrest's group in Waterloo). The simple geometry of a polymer film on a substrate with a step at the free surface is unfavourable due to the excess interface induced by the step. Laplace pressure will drive flow within the film which can be studied with optical and atomic force microscopies. Because of the excellent agreement between theory and experiment when we probe ``bulk-like'' properties, these studies provide an opportunity to study how such systems transition from the bulk to confined. Starting with some of the results of levelling experiments on simple stepped films as well as the levelling of polymer droplets on thin films, I will finish with a discussion on our more recent efforts to elucidate confinement effects.

  12. High Energy Density Polymer Film Capacitors

    DTIC Science & Technology

    2006-10-01

    are formed by vapor deposition of multifunctional acrylate monomers that are deposited on the PVDF as a thin liquid film and are cross linked using...the world. Vacuum Depositing Inc. American Thin Films Vapor Technologies Inc. 1294 Old Fern Valley Road 2010 East Hennepin Ave. Boulder Tech Center...78 5.5.1 Capacitors Values, Voltage Breakdown, and Energy Density ................ 79 APPENDIX A PVDF AND PET FILMS

  13. Charge transport across the metal-polymer film boundary

    NASA Astrophysics Data System (ADS)

    Yumaguzin, Yu. M.; Salikhov, T. R.; Shayakhmetov, R. U.; Salikhov, R. B.

    2016-08-01

    Thin polyaniline films were fabricated by thermal vacuum evaporation from a Knudsen effusion cell. The conducting properties of films synthesized under different evaporation conditions were studied. The enhancement of the emission capacity of a wolfram tip coated with a polyaniline film of a nanometer thickness was demonstrated experimentally. A model of the discovered effect was proposed. The obtained Fowler-Nordheim current-voltage characteristics were used to estimate the change in the electronic work function occurring when a thin film is deposited on the tip surface. The effective temperature of electrons emitted from the polyaniline film was determined based on the results of analysis of energy distributions, and the specific features of charge transport in the metal-polyaniline-vacuum system were examined. A model of energy bands of the metal-polymer film contact was also constructed.

  14. Simple push coating of polymer thin-film transistors

    NASA Astrophysics Data System (ADS)

    Ikawa, Mitsuhiro; Yamada, Toshikazu; Matsui, Hiroyuki; Minemawari, Hiromi; Tsutsumi, Jun'ya; Horii, Yoshinori; Chikamatsu, Masayuki; Azumi, Reiko; Kumai, Reiji; Hasegawa, Tatsuo

    2012-11-01

    Solution processibility is a unique advantage of organic semiconductors, permitting the low-cost production of flexible electronics under ambient conditions. However, the solution affinity to substrate surfaces remains a serious dilemma; liquid manipulation is more difficult on highly hydrophobic surfaces, but the use of such surfaces is indispensable for improving device characteristics. Here we demonstrate a simple technique, which we call ‘push coating’, to produce uniform large-area semiconducting polymer films over a hydrophobic surface with eliminating material loss. We utilize a poly(dimethylsiloxane)-based trilayer stamp whose conformal contact with the substrate enables capillarity-induced wetting of the surface. Films are formed through solvent sorption and retention in the stamp, allowing the stamp to be peeled perfectly from the film. The planar film formation on hydrophobic surfaces also enables subsequent fine film patterning. The technique improves the crystallinity and field-effect mobility of stamped semiconductor films, constituting a major step towards flexible electronics production.

  15. Tellurite glass thin films on silica and polymer using UV (193 nm) pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Zhao, Zhanxiang; Jose, Gin; Steenson, Paul; Bamiedakis, Nikos; Penty, Richard V.; White, Ian H.; Jha, Animesh

    2011-03-01

    Erbium-doped tellurite glass thin films were deposited using excimer (193 nm) laser ablation onto two different types of substrates: silica and polymer-coated silica for engineering optical integrated active-passive devices. The deposition conditions were optimized for both substrates in order to produce high-quality rare-earth (Er3+) ion-doped glass thin films with low propagation loss. The optical and spectroscopic properties of the deposited films, namely transmittance, fluorescence, lifetime as well as refractive indices at 633 nm were measured and analysed in detail.

  16. Vacuum deposited polymer films: Past, present, and future applications

    SciTech Connect

    Affinito, J.; Martin, P.; Gross, M.; Bennett, W.

    1994-11-01

    Two extremely high rate processes have been developed for the vacuum deposition of polymer thin films. Dubbed the PML (for Polymer Multi-Layer) and LML (for Liquid Multi-Layer) processes, the PML technique was originally developed for the manufacture of polymer/aluminum surface mount capacitors while the LML method arose from a need to fabricate lithium polymer batteries. These processes have since been found to be compatible with most other vacuum deposition techniques in, integrated, in-line coating processes. Battelle has developed an extensive program, and a great deal of hardware, to pursue a wide variety of PML and LML applications which integrate these two process technologies with other, conventional, vacuum deposition methods. The historical development of the technologies is reviewed and the Battelle PML/LML facilities are described. Current Battelle work involving solar thermal control films, PML QWOTs, and polymer/metal high reflectors are also discussed. Battelle PML work that is just starting, involving non-linear optical materials/devices, lithium polymer battery fabrication, electrochromic devices, and polymer/oxide multilayers, is discussed as well.

  17. Measuring the Thickness and Elastic Properties of Electroactive Thin-Film Polymers Using Platewave Dispersion Data

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; El-Azab, A.; Mal, Ajit K.

    1996-01-01

    Electroactive thin-film polymers are candidate sensors and actuators materials. They are also finding significant potential in muscle mechanisms and microelectromechanical systems (MEMS). In these applications, polymer thin films of thickness varying between 20 and 300 micrometers are utilized. The authors are currently studying the potential use of platewave dispersion curve measurements as an effective gauging tool for electroactive thin-film polymers.

  18. 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.

  19. Structural and ionic conductivity behavior in hydroxypropylmethylcellulose (HPMC) polymer films complexed with sodium iodide (NaI)

    NASA Astrophysics Data System (ADS)

    Rani, N. Sandhya; Sannappa, J.; Demappa, T.; Mahadevaiah

    2013-02-01

    Solid polymer electrolyte films based on Hydroxypropylmethylcellulose (HPMC) complexed with Sodium Iodide (NaI) were prepared using solution cast method. The dissolution of the salt into the polymer host and the micro structural properties of pure and NaI complexed HPMC polymer electrolyte films were confirmed by X - Ray diffraction (XRD) studies. The XRD results revealed that the amorphous domains of HPMC polymer matrix was increased with increase in the NaI salt concentration. The degree of crystallanity and crystallite size is high for pure HPMC samples. Direct current (dc) conductivity was measured in the temperature range of 313-383k. Temperature dependence of dc electrical conductivity and activation energy regions data indicated the dominance of ion type charge transport in these polymer electrolyte films.

  20. Effect of plasticizer on surface of free films prepared from aqueous solutions of salts of cationic polymers with different plasticizers

    NASA Astrophysics Data System (ADS)

    Bajdik, János; Fehér, Máté; Pintye-Hódi, Klára

    2007-06-01

    Acquisition of a more detailed understanding of all technological processes is currently a relevant tendency in pharmaceutical technology and hence in industry. A knowledge of film formation from dispersion of polymers is very important during the coating of solid dosage forms. This process and the structure of the film can be influenced by different additives. In the present study, taste-masking films were prepared from aqueous citric acid solutions of a cationic polymer (Eudragit ® E PO) with various hydrophilic plasticizers (glycerol, propylene glycol and different poly(ethylene glycols)). The mechanical properties, film thickness, wetting properties and surface free energy of the free films were studied. The aim was to evaluate the properties of surface of free films to predict the arrangement of macromolecules in films formed from aqueous solutions of salts of cationic polymers. A high molecular weight of the plasticizer decreased the work of deformation. The surface free energy and the polarity were highest for the film without plasticizer; the hydrophilic additives decreased these parameters. The direction of the change in polarity (a hydrophilic component caused a decrease in the polarity) was unexpected. It can be explained by the change in orientation of the macromolecules, a hydrophobic surface being formed. Examination of the mechanical properties and film thickness can furnish additional results towards a knowledge of film formation by this not frequently applied type of polymer from aqueous solution.

  1. Micro-indentation relaxation measurements in polymer thin films

    NASA Astrophysics Data System (ADS)

    Shinozaki, D. M.; Lu, Y.

    1997-07-01

    A micro-indenter consisting of a piezo-electric driven flat cylindrical punch has been used to measure the dynamic mechanical properties of polystyrene films as thin as 50 μm. The measured viscoelastic response was sensitive to the bonding of the polystyrene to an underlying silicon substrate for films which were thinner than one indenter diameter. The instrument therefore was shown to have practical use in measuring the dynamic mechanical response of polymer films, and the strength of bonding between disparate materials.

  2. Polymer interdiffusion and mechanical property development during latex film formation

    SciTech Connect

    Fu, Z.; Boczar, E.M.; Kirk, A.B.

    1995-12-31

    The interdiffusion of polymer chains across the latex boundaries during latex film formation has been studied using the fluorescence technique of direct energy transfer (DET) or small-angle neutron scattering technique (SANS) by several groups. The increase in mechanical strength and the interdiffusion depth determined by SANS has been correlated for several polystyrene latex systems during film formation. In this paper, we will present the correlation between the increase in mechanical strength and the interdiffusion depth for a poly (amyl methacrylate) latex system. Volume fractions of mixing (Fm) as a function of annealing time for two poly (amyl methacrylate) latex blend films were measured.

  3. Study of poly (3-hexylthiophene) conducting polymer thin film micro-sensor for hydrazine vapor detection

    NASA Astrophysics Data System (ADS)

    Yang, Hong

    This dissertation discussed the construction and investigation of a poly (3-hexylthiophene) conducting polymer based thin film micro-sensor for a real-time detection of hydrazine vapor at ambient pressure. A type of low cost, small size, passive poly (3-hexylthiophene) thin film micro-sensor was designed and fabricated. The micro-sensor platform consisted of a rectangular shaped inert substrate and gold interdigited electrode pairs. A layer of poly (3-hexylthiophene) thin film was coated onto the sensor platform using a spin coating method, and nitrosonium hexafluorophosphate (NOPF6) was used to dope the poly (3-hexylthiophene) thin film to increase its electrical conductivity and form the finished sensor. The basic responses of the sensor to hydrazine vapor were experimentally investigated. The primary results showed that the sensor responded to hydrazine vapor in less than a few seconds; attained orders of magnitude change in normalized resistance during hydrazine exposure, and was not easily saturated. The interaction between the hydrazine gas molecules and doped poly (3-hexylthiophene) thin film was studied. The plausible mechanism was determined as: Charge carriers inside the doped poly (3-hexylthiophene) thin film were depleted during the oxidation-reduction chemical reaction between the hydrazine vapor and polymer film, resulting a reduction in the polymer film's electrical conductivity. Experiments were also conducted to find out the effects of hydrazine concentration, poly (3-hexylthiophene) thin film thickness, sensor storage time, environment temperature, and environment humidity on the sensor's performance. The response rate of the sensor under different sensing conditions was calculated and discussed. A diffusion-reaction model was applied to simulate the interaction between hydrazine molecules and doped poly (3-hexylthiophene) thin film. The profiles of hydrazine gas diffusion and positive charge carrier neutralization in the polymer film were

  4. Transparent lithiated polymer films for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Mabe, Andrew N.; Auxier, John D.; Urffer, Matthew J.; Penumadu, Dayakar; Schweitzer, George K.; Miller, Laurence F.

    2013-09-01

    Novel water-soluble 6Li loaded copolymer scintillation films have been designed and fabricated to detect thermal neutrons. Styrene and maleic anhydride were copolymerized to form an alternating copolymer, then the anhydride functionality was hydrolyzed using 6Li hydroxide. The resulting poly(styrene-co-lithium maleate) was mixed with salicylic acid as a fluor and cast as a thin film from water. The maximum 6Li loading obtained that resulted in a transparent film was 4.36% by mass (6Li to polymer). The optimum fluorescence output was obtained for 11.7% salicylic acid by mass, presumably in the form of lithium salicylate, resulting in an optimum film containing 3.85% by mass of 6Li. A facile and robust synthesis method, film fabrication protocol, photoluminescence results, and scintillation responses are reported herein.

  5. Co-polymer Films for Sensors

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2012-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  6. Co-polymer films for sensors

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2010-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  7. Direct observation of athermal photofluidisation in azo-polymer films.

    PubMed

    Hurduc, Nicolae; Donose, Bogdan C; Macovei, Alina; Paius, Cristina; Ibanescu, Constanta; Scutaru, Dan; Hamel, Matthieu; Branza-Nichita, Norica; Rocha, Licinio

    2014-07-14

    The surface relief gratings (SRGs) can be generated when azo-polymer films are exposed to laser beam interference as a result of mass migration. Despite considerable research effort over the past two decades this complex phenomenon remains incompletely understood. Here we show, for the first time, the athermal photofluidisation of azo-polysiloxane films exposed to 488 nm light, directly monitored by optical microscopy. A process of surface relief erasure occurring in parallel with its inscription was also observed during laser irradiation. We therefore propose a new mechanism of SRG formation, based on three different processes: (1) the polymer photo-fluidization in illuminated regions, (2) the mass displacement from illuminated to dark regions and (3) the inverse mass displacement, from dark to illuminated regions. The mechanical properties of the films during UV light irradiation were investigated by classical rheology and, for the first time, by using amplitude modulation-frequency modulation atomic force microscopy (AM-FM AFM).

  8. Anti-biofouling properties of amphiphilic phosphorylcholine polymer films.

    PubMed

    Li, Yan; Liu, Cheng-Mei; Yang, Jin-Ying; Gao, Ya-Hui; Li, Xue-Song; Que, Guo-He; Lu, J R

    2011-07-01

    Surfaces of amphiphilic phosphorylcholine polymer (PC1036) prepared by spin-coating were characterized by spectroscopic ellipsometry, water contact angle and atomic force microscopy. The antifouling properties of the PC1036 films to marine benthic diatom Nitzschia closterium MMDL533 were also investigated. The results showed that the dry PC1036 film promoted the adhesion of N. closterium MMDL533 because the hydrophobic lauryl groups were present in the film surface. The 2 h-swelled PC1036 films had excellent anti-fouling properties with extremely low attachment densities and retention densities no matter what the annealing temperature was. The thickness of the coated films lower than 147 Å had a profound effect on the film anti-fouling properties. Otherwise, when the film thickness was higher than that value, there was no more improvement of diatom cell reduction observed. The annealing temperature had only a little effect on the film resistant to diatom adhesion, which might be attributed to two factors including the PC group packing densities in the outer PC layer and the equilibrated water volume fraction in the 2 h-swelled PC1036 films.

  9. Thin film conductive polymer for microactuator and micromuscle applications

    SciTech Connect

    Lee, A.P.; Hong, K.; Trevino, J.; Northrup, M.A.

    1994-04-14

    Conductive polymer/polyimide bimorphic microcantilevers have been actuated vertically (out-of-plane) upon the volumetric changes induced by electrochemical doping of the polymer. The microcantilevers that are 200-500 {mu}m in length and 50-100 {mu}m in width can be fully extended from a circularly-curled geometry, and thus generate more than 100 {mu}m displacement. Dynamically the microcantilevers have been driven as fast as 1.2 Hz and the polymer was stable for over a week stored in air and light. Residual stresses in the polymer film is estimated to be as high as 254 MPa, and actuation stresses are as high as 50 MPa.

  10. Synthesis and characteristics of metal-phthalocyanine-polymer composite films

    NASA Astrophysics Data System (ADS)

    Chen, Jianming; Zhang, Jiancheng; Shen, Yue; Liu, Xiuhong

    2000-11-01

    Fe(III)-2,9,16,23-tertracarboxy-phthalocyanine (Fe (III)- taPc) was synthesized, and was bonded to polystyrene (PS) with covalence by Friedel-Crafts reaction to form a new polymer [Fe (111)-taPc-PS] [polymer (II)]. Uv-Vis and Infrared spectra indicated that Fe (III)-taPc was successfully bonded to PS. A photoreceptor device of sandwich structure consisting of alternate layers of polymer (II) and fullerene (C60) was prepared. The experiment results show that the photoconductivity of the photoreceptor is higher than that of the single-layer film of polymer (II) or C60, because of the charge-transfer effect between the layers.

  11. Exciton diffusion and relaxation in methyl-substituted polyparaphenylene polymer films.

    PubMed

    Gulbinas, V; Mineviciūte, I; Hertel, D; Wellander, R; Yartsev, A; Sundström, V

    2007-10-14

    Exciton diffusion in ladder-type methyl-substituted polyparaphenylene film and solution was investigated by means of femtosecond pump-probe spectroscopy using a combined approach, analyzing exciton-exciton annihilation, and transient absorption depolarization properties. We show that the different views on the exciton dynamics offered by anisotropy decay and annihilation are required in order to obtain a correct picture of the energy transfer dynamics. Comparison of the exciton diffusion coefficient and exciton diffusion radius obtained for polymer film with the two techniques reveals that there is substantial short-range order in the film. Also in isolated chains there is considerable amount of order, as revealed from only partial anisotropy decay, which shows that only a small fraction of the excitons move to differently oriented polymer segments. It is further concluded that interchain energy transfer is faster than intrachain transfer, mainly as a result of shorter interchain distances between chromophoric units.

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

    NASA Astrophysics Data System (ADS)

    Schaubroeck, David; De Smet, Jelle; Willems, Wouter; Cools, Pieter; De Geyter, Nathalie; Morent, Rino; De Smet, Herbert; Van Steenbeerge, Geert

    2016-07-01

    Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

  13. 78 FR 55641 - Polyurethane-Type Polymers; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-11

    ... AGENCY 40 CFR Part 180 Polyurethane-Type Polymers; Tolerance Exemption AGENCY: Environmental Protection... of a tolerance for residues of polymers produced by the reaction of either 1,6-hexanediisocyanate; 2..., octadecanol, and octadec-9-enol (also known as polyurethane-type polymers), when used as an inert...

  14. Metallic waveguide mirrors in polymer film waveguides

    NASA Astrophysics Data System (ADS)

    Wolff, S.; Giehl, A. R.; Renno, M.; Fouckhardt, H.

    2001-10-01

    A technology for the fabrication of metallic waveguide mirrors is developed. Plane and curved waveguide mirrors, the latter acting in the same way as cylindrical lenses, are realized in benzocyclobutene (BCB) film waveguides. The waveguide mirror structure is dry-etched into the BCB film waveguide. To enhance the reflectivity of the waveguide mirrors, the waveguide edge is metallized. The BCB film waveguide mirrors are characterized with respect to waveguide attenuation and mirror reflectivity. The waveguide attenuation of the processed BCB waveguide is 0.5 dB/cm. Ag-coated BCB waveguide mirrors show a reflectivity of 71%. The efficiency of total internal reflection (TIR, i.e. in the case without metallization) at the dry-etched waveguide edge is 74%. As an application of the BCB waveguide mirrors a hybrid integrated optical module for Fourier-optical transverse mode selection in broad area lasers (BAL) is proposed.

  15. Cell attachment to PET films coated with a thermo-sensitive block co-polymer with different chemical composition.

    PubMed

    Takamoto, Tomoaki; Yasuda, Kaori; Tsujino, Tomohiro; Sugihara, Shinji; Kanaoka, Shokyoku; Aoshima, Sadahito; Tabata, Yasuhiko

    2007-01-01

    This objective of this study is to characterize the surface of poly(ethylene terephthalate) (PET) films coated with the thermo-sensitive di-block co-polymers of 2-ethoxyethyl vinyl ether and 2-phenoxyethyl vinyl ether segments (EOVE-b-PhOVE) with a high polydispersity and evaluate the behavior of cell attachment on them at different temperatures. The EOVE segment possessed a low critical solution temperature at 20 degrees C while the hydrophobic PhOVE segment functioned as the site to allow the co-polymer to adsorb onto the PET films. X-ray photoelectron spectroscopy and contact angle measurements revealed that the PET film was coated with the EOVE-b-PhOVE co-polymers. The density of co-polymers coated increased with the concentration of co-polymers used for coating. Irrespective of the co-polymer type, 3T3L1 cells attached on the surface of coated films at 37 degrees C, while the cells showed a spread shape, which is similar to that of cells attached on the original non-coated film. However, when the temperature decreased from 37 to 4 degrees C, the cell shape changed to be round, in contrast to that of the original PET film. The percent increase of round cells depended on the coating density and the polymerization degree of EOVE segment.

  16. Strong Composition Effects in All-Polymer Phototransistors with Bulk Heterojunction Layers of p-type and n-type Conjugated Polymers.

    PubMed

    Han, Hyemi; Lee, Chulyeon; Kim, Hwajeong; Seo, Jooyeok; Song, Myeonghun; Nam, Sungho; Kim, Youngkyoo

    2017-01-11

    We report the composition effect of polymeric sensing channel layers on the performance of all-polymer phototransistors featuring bulk heterojunction (BHJ) structure of electron-donating (p-type) and electron-accepting (n-type) polymers. As an n-type component, poly(3-hexylthiopehe-co-benzothiadiazole) end-capped with 4-hexylthiophene (THBT-4ht) was synthesized via two-step reactions. A well-studied conjugated polymer, poly(3-hexylthiophene) (P3HT), was employed as a p-type polymer. The composition of BHJ (P3HT:THBT-4ht) films was studied in detail by varying the THBT-4ht contents (0, 1, 3, 5, 10, 20, 30, 40, and 100 wt %). The best charge separation in the P3HT:THBT-4ht films was measured at 30 wt % by the photoluminescence (PL) study, while the charge transport characteristics of devices were improved at the low THBT-4ht contents (<10 wt %). The photosensing experiments revealed that the photosensivity of all-polymer phototransistors was higher than that of the phototransistors with the pristine P3HT layers and strongly dependent on the BHJ composition. The highest (corrected) responsivity (RC) was achieved at 20 wt %, which can be attributable to the balance between the best charge separation and transport states, as investigated for crystal nanostructures and surface morphology by employing synchrotron-radiation grazing-incidence wide-angle X-ray scattering, high-resolution/scanning transmission electron microscopy, and atomic force microscopy.

  17. Multilevel conductance switching in polymer films

    NASA Astrophysics Data System (ADS)

    Lauters, M.; McCarthy, B.; Sarid, D.; Jabbour, G. E.

    2006-07-01

    Multilevel conductance switching in poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) films is demonstrated. A thin-film structure, ITO-coated glass/MEH-PPV/Al, has shown the ability to store a continuum of conductance states. These states are nonvolatile and can be switched reproducibly by applying appropriate programing biases above a certain threshold voltage. The electrical conductivity of the highest and lowest states can differ by five orders of magnitude. Furthermore, these devices exhibit good cyclic switching characteristics and retention times of several weeks.

  18. Deformation Hysteresis of Electrohydrodynamic Patterning on a Thin Polymer Film.

    PubMed

    Yang, Qingzhen; Li, Ben Q; Tian, Hongmiao; Li, Xiangming; Shao, Jinyou; Chen, Xiaoliang; Xu, Feng

    2016-07-13

    Electrohydrodynamic patterning is a technique that enables micro/nanostructures via imposing an external voltage on thin polymer films. In this investigation, we studied the electrohydrodynamic patterning theoretically and experimentally, with special interest focused on the equilibrium state. It is found that the equilibrium structure height increases with the voltage. In addition, we have observed, and believe it to be the first time, a hysteresis phenomenon exists in the relationship between the voltage and structure height. With an increase in the voltage, a critical value (the first critical voltage) is noticed, above which the polymer film would increase dramatically until it comes into contact with the template. However, with a decrease in the voltage, a smaller voltage (the second critical voltage) is needed to detach the polymer from the template. The mismatch of the first and second critical voltages distorts the voltage-structure height curve into an "S" shape. Such a phenomenon is verified for three representative templates and also by experiments. Furthermore, the effects of some parameters (e.g., polymer film thickness and dielectric constant) on this hysteresis phenomenon are also discussed.

  19. Nanodiamond-polymer nanoparticle composites and their thin films

    NASA Astrophysics Data System (ADS)

    Attia, N. F.; Rao, J. P.; Geckeler, K. E.

    2014-04-01

    Nanodiamonds obtained from detonation processes have received a great deal of attention during the past decades because of their unique properties and applications. The dispersion of nanodiamond particles can be achieved by different methods including the use of polymer nanoparticles. Here, we describe the dispersion of nanodiamonds in conjunction with sonication using poly(vinylpyrrolidone) nanoparticles with a particle size range of 23.3-61.3 nm, providing a good, economic, and efficient method for the dispersion. The average particle size was found to be 37.5 nm, as confirmed by transmission electron microscopy. The interaction between the nanodiamonds and polymer nanoparticles was characterized by FTIR spectroscopy and the effect of the polymer nanoparticle concentration, sonication time, and frequency on the dispersion process of nanodiamonds is highlighted. In addition, we prepared thin films of nanodiamond-polymer composites with different nanodiamond contents that showed good nanodiamond dispersion. The thin film can act as a UV filter and is transparent in the visible region. The thin films of nanodiamond-poly(vinylpyrrolidone) nanoparticles were characterized by SEM and UV-Vis spectroscopy.

  20. Template-assisted generation of nanocavities within plasma polymer films.

    PubMed

    Vasilev, Krasimir; Casanal, Ana; Challougui, Hela; Griesser, Hans J

    2009-05-21

    The generation of nanosized cavities within thin film layers is of interest for a number of fundamental and applied reasons. One challenge is to make such systems sufficiently robust mechanically. Plasma polymer (pp) films possess excellent mechanical stability if deposition conditions are selected such as to achieve a sufficient density of cross-linking and resistance to extraction of polymeric material by solvents. In this study, gold nanoparticles of 15 and 70 nm diameter were used as sacrificial templates to generate nanocavities in pp films of various thickness values in the tens of nanometers range. A first pp layer was deposited onto substrates using n-heptylamine (HA) to a thickness of 20 nm. Carboxy-thiolated gold nanoparticles were electrostatically bound onto the surface amine groups of the n-heptylamine plasma polymer (HApp) layer. A second HApp layer was then coated to various thicknesses onto the nanoparticle/HApp surface. The template particles embedded thus in-between the two HApp layers were then dissolved using aqueous KCN solution; monitoring of the plasmon resonance band of the gold nanoparticles enabled verification of template stripping and measurement of the kinetics of stripping. AFM topography images showed little change on extraction of the template nanoparticles, indicating that the plasma polymer layer maintained structural integrity upon template extraction and subsequent drying, and thereby prevented collapse of the empty nanocavities. The concept of template stripping to generate controlled size free volume in thin plasma polymer layers is thus shown to produce robust structures.

  1. Biotin selective polymer nano-films

    PubMed Central

    2014-01-01

    Background The interaction between biotin and avidin is utilized in a wide range of assay and diagnostic systems. A robust material capable of binding biotin should offer scope in the development of reusable assay materials and biosensor recognition elements. Results Biotin-selective thin (3–5 nm) films have been fabricated on hexadecanethiol self assembled monolayer (SAM) coated Au/quartz resonators. The films were prepared based upon a molecular imprinting strategy where N,N'-methylenebisacrylamide and 2-acrylamido-2-methylpropanesulfonic acid were copolymerized and grafted to the SAM-coated surface in the presence of biotin methyl ester using photoinitiation with physisorbed benzophenone. The biotinyl moiety selectivity of the resonators efficiently differentiated biotinylated peptidic or carbohydrate structures from their native counterparts. Conclusions Molecularly imprinted ultra thin films can be used for the selective recognition of biotinylated structures in a quartz crystal microbalance sensing platform. These films are stable for periods of at least a month. This strategy should prove of interest for use in other sensing and assay systems. PMID:24655809

  2. Inorganic-polymer-derived dielectric films

    DOEpatents

    Brinker, C.J.; Keefer, K.D.; Lenahan, P.M.

    1985-02-25

    A method is disclosed for coating a substrate with a thin film of a predetermined porosity. The method comprises: depositing the thin film on the substrate from a non-gelled solution comprising at least one metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base; prior to said depositing step, controlling the porosity and structure of said coating for a given composition of said solution exclusive of the acid or base component and the water component, by adjusting each of the water content, the pH, the temperature and the time of standing of said solution, increasing/descreasing the water content or the pH to increase/decrease the pore size of said coating, and increasing/decreasing the temperature or time of standing of said solution to increase/decrease the pore size of said coating; and curing said deposited film at a temperature effective for curing whereby there is obtained a thin film coating of a predetermined porosity on the substrate.

  3. Molecular Dynamics Simulations of Gas Transport in Polymer Films

    NASA Astrophysics Data System (ADS)

    Whitley, David; Butler, Simon; Adolf, David

    2010-03-01

    Parallel molecular dynamics simulations have been carried out to determine the permeability of O2 and N2 through polyethylene terephthalate, polypropylene and cis(1-4) polybutadiene. The permeability of both mixed and unmixed gas penetrants is studied within films of these well known gas barrier polymers. Results are obtained either through the solubility and diffusion (i.e. P=D*S) or via the permeability directly. Encouraging results are obtained. Additional analysis focuses on ``unmixed/mixed gas'' intracomparisons of the simulated permeability data in addition to corresponding penetrant and host polymer local dynamics.

  4. Manufacturing polymer thin films in a micro-gravity environment

    NASA Technical Reports Server (NTRS)

    Vera, Ivan

    1987-01-01

    This project represents Venezuela's first scientific experiment in space. The apparatus for the automatic casting of two polymer thin films will be contained in NASA's Payload No. G-559 of the Get Away Special program for a future orbital space flight in the U.S. Space Shuttle. Semi-permeable polymer membranes have important applications in a variety of fields, such as medicine, energy, and pharmaceuticals and in general fluid separation processes, such as reverse osmosis, ultrafiltration, and electrodialysis. The casting of semi-permeable membranes in space will help to identify the roles of convection in determining the structure of these membranes.

  5. Dynamic Mechanical Characterization of Thin Film Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Herring, Helen M.; Gates, Thomas S. (Technical Monitor)

    2003-01-01

    Many new materials are being produced for aerospace applications with the objective of maximizing certain ideal properties without sacrificing others. Polymer composites in various forms and configurations are being developed in an effort to provide lighter weight construction and better thermal and electrical properties and still maintain adequate strength and stability. To this end, thin film polymer nanocomposites, synthesized for the purpose of influencing electrical conductivity using metal oxide particles as filler without incurring losses in mechanical properties, were examined to determine elastic modulus and degree of dispersion of particles. The effects of various metal oxides on these properties will be discussed.

  6. Plasma deposition of polymer composite films incorporating nanocellulose whiskers

    NASA Astrophysics Data System (ADS)

    Samyn, P.; Airoudj, A.; Laborie, M.-P.; Mathew, A. P.; Roucoules, V.

    2011-11-01

    In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

  7. Self-Supported Crack-Free Conducting Polymer Films with Stabilized Wrinkling Patterns and Their Applications

    PubMed Central

    Xie, Jixun; Han, Xue; Ji, Haipeng; Wang, Juanjuan; Zhao, Jingxin; Lu, Conghua

    2016-01-01

    Self-supported conducting polymer films with controlled microarchitectures are highly attractive from fundamental and applied points of view. Here a versatile strategy is demonstrated to fabricate thin free-standing crack-free polyaniline (PANI)-based films with stable wrinkling patterns. It is based on oxidization polymerization of pyrrole inside a pre-wrinkled PANI film, in which the wrinkled PANI film is used both as a template and oxidizing agent for the first time. The subsequently grown polypyrrole (PPy) and the formation of interpenetrated PANI/PPy networks play a decisive role in enhancing the film integrity and the stability of wrinkles. This enhancing effect is attributed to the modification of internal stresses by the interpenetrated PANI/PPy microstructures. Consequently, a crack-free film with stable controlled wrinkles such as the wavelength, orientation and spatial location has been achieved. Moreover, the wrinkling PANI/PPy film can be removed from the initially deposited substrate to become free-standing. It can be further transferred onto target substrates to fabricate hierarchical patterns and functional devices such as flexible electrodes, gas sensors, and surface-enhanced Raman scattering substrates. This simple universal enhancing strategy has been extended to fabrication of other PANI-based composite systems with crack-free film integrity and stabilized surface patterns, irrespective of pattern types and film geometries. PMID:27827459

  8. Self-Supported Crack-Free Conducting Polymer Films with Stabilized Wrinkling Patterns and Their Applications

    NASA Astrophysics Data System (ADS)

    Xie, Jixun; Han, Xue; Ji, Haipeng; Wang, Juanjuan; Zhao, Jingxin; Lu, Conghua

    2016-11-01

    Self-supported conducting polymer films with controlled microarchitectures are highly attractive from fundamental and applied points of view. Here a versatile strategy is demonstrated to fabricate thin free-standing crack-free polyaniline (PANI)-based films with stable wrinkling patterns. It is based on oxidization polymerization of pyrrole inside a pre-wrinkled PANI film, in which the wrinkled PANI film is used both as a template and oxidizing agent for the first time. The subsequently grown polypyrrole (PPy) and the formation of interpenetrated PANI/PPy networks play a decisive role in enhancing the film integrity and the stability of wrinkles. This enhancing effect is attributed to the modification of internal stresses by the interpenetrated PANI/PPy microstructures. Consequently, a crack-free film with stable controlled wrinkles such as the wavelength, orientation and spatial location has been achieved. Moreover, the wrinkling PANI/PPy film can be removed from the initially deposited substrate to become free-standing. It can be further transferred onto target substrates to fabricate hierarchical patterns and functional devices such as flexible electrodes, gas sensors, and surface-enhanced Raman scattering substrates. This simple universal enhancing strategy has been extended to fabrication of other PANI-based composite systems with crack-free film integrity and stabilized surface patterns, irrespective of pattern types and film geometries.

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

    NASA Astrophysics Data System (ADS)

    Linde, Felix; Sekhar Yadavalli, Nataraja; Santer, Svetlana

    2013-12-01

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

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

    SciTech Connect

    Linde, Felix; Sekhar Yadavalli, Nataraja; Santer, Svetlana

    2013-12-16

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

  11. 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.

  12. Convergence to Self-Similar Regimes in Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Benzaquen, Michael; Salez, Thomas; Raphaël, Elie; Elie Raphaël Team; Kari Dalnoki-Veress Team

    2013-03-01

    The surface of a thin liquid film with nonconstant curvature is unstable, as the Laplace pressure drives a flow mediated by viscosity. Recent experiments and theory applied to stepped polymer films have shown excellent agreement and provide a technique for the study of polymer confinement, the glass transition, and slip at the fluid substrate interface to name a few. The thin film equation governs the evolution of the free surface profile in the lubrication approximation. Despite many efforts, this equation remains only partially solved. We present an analytical and numerical study of the thin film equation. Linearising this equation enables us to derive the Green's function of the problem and therefore obtain a complete set of solutions. We show that the solutions of the problem with equilibrium boundary conditions uniformly converge in time towards a first kind self-similar universal attractor. A numerical study enables us to extend our results to the nonlinear thin film equation. Laboratoire Physico-Chimie Théorique, UMR CNRS 7083 Gulliver. ESPCI, 10 rue Vauquelin, 75005, Paris, France.

  13. Entanglement effects in capillary waves on liquid polymer films.

    PubMed

    Jiang, Zhang; Mukhopadhyay, Mrinmay K; Song, Sanghoon; Narayanan, Suresh; Lurio, L B; Kim, Hyunjung; Sinha, Sunil K

    2008-12-12

    Overdamped surface capillary wave relaxations on molten polymer films were measured using x-ray photon correlation spectroscopy. We found a transition from a single through a stretched to another single exponential regime as the temperature is decreased from well above to near the bulk glass transition temperature. A universal scaling of the dynamics was discovered over a wide range of film thicknesses, temperatures, and molecular weights (except in the multiple relaxation regime). These observations are justified by hydrodynamic theory and the time-temperature superposition principle by considering an effective viscosity instead of the bulk zero shear viscosity.

  14. Second-harmonic generation in a polymer Langmuir - Blodgett film

    SciTech Connect

    Ivanova, V N; Kudryavtsev, V V; Lebedeva, G K; Maslyanitsyn, I A; Shigorin, V D; Chudinova, G K

    1998-09-30

    Second-harmonic generation was used to investigate nonlinear optical properties and the structure of multilayer Langmuir - Blodgett films of a copolymer of fluoroalkylmethacrylate with methacrylates containing an azo dye and a cinnamoyl group inside a chain. Quantum-chemical calculations were made of the components of the molecular hyperpolarisability tensor in which the intermolecular interactions were taken into account. The orientation of nonlinear optical fragments of a polymer chain relative to the substrate and components of the quadratic optical susceptibility tensor of the film were determined. (nonlinear optical phenomena)

  15. Anisotropic Liquid Microcapsules from Biomimetic Self-Folding Polymer Films.

    PubMed

    Zakharchenko, Svetlana; Ionov, Leonid

    2015-06-17

    We demonstrated a novel approach for the fabrication of anisotropic capsules with liquid content using biomimetic self-folding thermoresponsive polymer films. The behavior of self-folding films is very similar to actuation in plants, where nonhomogenous swelling results in complex movements such as twisting, bending, or folding. This approach allows the design of anisotropic liquid capsules with rodlike and dumbbell-like morphologies. We found that these capsules are able to assemble into different complex structures, such as nematic-like one and 3D network depending on their morphology.

  16. Large and Reversible Plasmon Tuning using Ultrathin Responsive Polymer film

    NASA Astrophysics Data System (ADS)

    Singamaneni, Srikanth; Nergiz, Saide

    2011-03-01

    We demonstrate reversible linear and branched aggregation of gold nanoparticles adsorbed on an ultrathin responsive polymer ((poly(4-vinyl pyridine), P4VP) film. P4VP is a weak cationic polymer, which exhibits a reversible coil to globule transition with change in external pH. Atomic force microscopy revealed that in the coiled state (below the isoelectric point of the polymer) of the polymer chains, gold nanoparticles adsorbed on the polymer layer existed as primarily individual nanoparticles. On the other hand, lowering the pH caused the polymer chains to transition from coil to globule state, resulting in aggregation of the nanoparticles into linear and branched chains. Reversible aggregation of the nanoparticles results in a dramatic change in the optical properties of the metal nanostructures. Apart from the large redistribution of the intensity between the individual (530 nm) and coupled (650 nm) plasmon bands, the coupled plasmon band exhibits a shift of nearly 60 nm with change in external pH. The pH triggered aggregation of the nanoparticles and the dramatic change in the optical properties associated with the same can form an excellent platform for colorimetric sensing. The work reported here is supported by the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine.

  17. 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.

  18. Elasto-Optical Properties of Thin Polymer Films by Prism Coupling Technique

    NASA Astrophysics Data System (ADS)

    Ay, Feridun; Agan, Sedat; Kocabas, Askin; Aydinli, Atilla

    2004-05-01

    Reliable measurement of stress dependent refractive index of thin polymer films has been achieved. The effect of the applied stress on the refractive index and birefringence of the films was investigated. The out-of-plane elastic moduli of the thin polymer films were deduced by using the same prism coupling setup. Three dimensional finite element method (FEM) analysis was used to obtain the principal stresses for each polymer film and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined, for the first time.

  19. Intricacies of Polymer Dewetting: Nanoscaled Architectures for the Tailored Control of Polystyrene Thin Film Stability

    NASA Astrophysics Data System (ADS)

    Cheung, Justin; Sen, Mani; Chen, Zhizhao; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori; Satija, Sushil

    Recently, structural properties of polymer thin films have garnered attention for their relevance in the fields of organic photovoltaics and biosensors. The dewetting of polymer films poses an obstacle in the face of widespread implementation. For this study, we show that adsorbed polymer chains on a substrate surface play crucial roles in film stability. Polystyrene (PS) thin films (20 nm in thickness) with different molecular weights (Mw) on silicon (Si) substrates were used as a model. The PS films were annealed at high temperatures for several days, and Mw dependence on film stability was evidenced. At the same time, the annealed PS films were leached with a good solvent and the residue films (i.e., irreversibly adsorbed layers) were characterized by x-ray reflectivity (XR). We reveal strong correlation between film stability and two different interfacial structures of the adsorbed polymer chains: their opposing wettability against chemically identical free polymer chains results in a wetting-dewetting transition at the adsorbed polymer-free polymer interface. This is a unique aspect of polymer thin film stability and may be generalizable to other polymer systems regardless of the magnitude of solid-polymer attractive interactions. We acknowledge the financial support of NSF Grant (CMMI-1332499).

  20. Ion beam sputtering of fluoropolymers. [etching polymer films and target surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1978-01-01

    Ion beam sputter processing rates as well as pertinent characteristics of etched targets and films are described. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Sputter target and film characteristics documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs are included.

  1. Polymer Substrates For Lightweight, Thin-Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Lewis, Carol R.

    1993-01-01

    Substrates survive high deposition temperatures. High-temperature-resistant polymers candidate materials for use as substrates of lightweight, flexible, radiation-resistant solar photovoltaic cells. According to proposal, thin films of copper indium diselenide or cadmium telluride deposited on substrates to serve as active semiconductor layers of cells, parts of photovoltaic power arrays having exceptionally high power-to-weight ratios. Flexibility of cells exploited to make arrays rolled up for storage.

  2. Nanoscale porosity in polymer films: fabrication and therapeutic applications

    PubMed Central

    Bernards, Daniel A.; Desai, Tejal A.

    2011-01-01

    This review focuses on current developments in the field of nanostructured bulk polymers and their application in bioengineering and therapeutic sciences. In contrast to well-established nanoscale materials, such as nanoparticles and nanofibers, bulk nanostructured polymers combine nanoscale structure in a macroscopic construct, which enables unique application of these materials. Contemporary fabrication and processing techniques capable of producing nanoporous polymer films are reviewed. Focus is placed on techniques capable of sub-100 nm features since this range approaches the size scale of biological components, such as proteins and viruses. The attributes of these techniques are compared, with an emphasis on the characteristic advantages and limitations of each method. Finally, application of these materials to biofiltration, immunoisolation, and drug delivery are reviewed. PMID:22140398

  3. Microwave absorption of free carriers in doped conjugated polymer films

    NASA Astrophysics Data System (ADS)

    Rumbles, Garry

    Flash photolysis time-resolved microwave conductivity (fp-TRMC) is a powerful spectroscopic tool for the detection of mobile charges in organic systems, such as conjugated polymers. We will report on a study of charge carrier generation in a number of polymer systems where the solid-state microstructure (SSM) of the thin films can be controlled using both molecular structure and processing conditions. By incorporating a low concentration of molecular acceptors, such as metallo-phthalocyanines, as well as substituted fullerenes and perylenes, the driving force for photoinduced electron transfer can be controlled through the excited state energy and the reduction potential. Our results indicate the importance of the crystalline phase of the polymer to stabilise and reduce the rate of recombination of the holes with the electrons that remain trapped on the acceptor. In addition, the role that the SSM plays on the stabilization of bound electron-hole pairs, or charge-transfer (CT) states will be examined.

  4. Spontaneous thermally-induced delamination of polymer films

    NASA Astrophysics Data System (ADS)

    Kohli, Punit; Jiao, Kexin; Zhou, Chuanhong; Wynne, Jared; Poude, Anish; Chu, Philip; Chemistry; Biochemistry Collaboration; Mechanical Engineering Collaboration

    In this talk, we will discuss spontaneous thermally-induced biaxial delamination of thin polymer films from flat surfaces. The delamination results in the formation of ultra-high aspect ratio (up to 1000) of micro-ribbons of polydimethylsiloxane. The thickness, width, and length of the micro-ribbons is about 10 μm, 100 μm, and up to many centimeter respectively. We will demonstrate that the formation of polymer micro-ribbons can be experimentally controlled. Specifically, the thickness and mechanical properties of polymer, and geometrical and physical properties of the substrate played crucial roles in defining the delamination process. From the practical viewpoint, we demonstrate the use of the micro-ribbons for imaging and separation applications. NSF, NIH, and SIUC.

  5. A pH/enzyme-responsive polymer film consisting of Eudragit FS 30 D and arabinoxylane as a potential material formulation for colon-specific drug delivery system.

    PubMed

    Rabito, Mirela Fulgencio; Reis, Adriano Valim; Freitas, Adonilson dos Reis; Tambourgi, Elias Basile; Cavalcanti, Osvaldo Albuquerque

    2012-01-01

    Polymer film based on pH-dependent Eudragit FS 30 D acrylic polymer in association with arabinoxylane, a polysaccharide issued from gum psyllium, was produced by way of solvent casting. Physical-chemical characterization of the polymer film samples was performed by means of thermogravimetry (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Furthermore, water-equilibrium swelling index (I(s)) and weight loss of the films in KCl buffer solution of pH 1.2, in KH(2)PO(4) buffer solution of pH 5.0, or in KH(2)PO(4) buffer solution of pH 5.0 consisting of 4% enzyme Pectinex 3X-L (w/v) were also carried out for the film characterization. No chemical interactions between the Eudragit FS 30 D and the arabinoxylane polymer chains were evidenced, thus suggesting that the film-forming polymer structure was obtained from a physical mixture of both polymers. The arabinoxylane-loader films showed a more pronounced weight loss after their immersion in buffer solution containing enzyme Pectinex 3X-L. The introduction of the arabinoxylane makes the film more susceptible to undergo an enzymatic degradation. This meant that the enzyme-dependent propriety issued from the arabinoxylane has been imprinted into the film formulation. This type of polymer film is an interesting system for applications in colon-specific drug delivery system.

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

    NASA Technical Reports Server (NTRS)

    Herring, Helen

    2003-01-01

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

  7. Chemical vapor deposition of conformal, functional, and responsive polymer films.

    PubMed

    Alf, Mahriah E; Asatekin, Ayse; Barr, Miles C; Baxamusa, Salmaan H; Chelawat, Hitesh; Ozaydin-Ince, Gozde; Petruczok, Christy D; Sreenivasan, Ramaswamy; Tenhaeff, Wyatt E; Trujillo, Nathan J; Vaddiraju, Sreeram; Xu, Jingjing; Gleason, Karen K

    2010-05-11

    Chemical vapor deposition (CVD) polymerization utilizes the delivery of vapor-phase monomers to form chemically well-defined polymeric films directly on the surface of a substrate. CVD polymers are desirable as conformal surface modification layers exhibiting strong retention of organic functional groups, and, in some cases, are responsive to external stimuli. Traditional wet-chemical chain- and step-growth mechanisms guide the development of new heterogeneous CVD polymerization techniques. Commonality with inorganic CVD methods facilitates the fabrication of hybrid devices. CVD polymers bridge microfabrication technology with chemical, biological, and nanoparticle systems and assembly. Robust interfaces can be achieved through covalent grafting enabling high-resolution (60 nm) patterning, even on flexible substrates. Utilizing only low-energy input to drive selective chemistry, modest vacuum, and room-temperature substrates, CVD polymerization is compatible with thermally sensitive substrates, such as paper, textiles, and plastics. CVD methods are particularly valuable for insoluble and infusible films, including fluoropolymers, electrically conductive polymers, and controllably crosslinked networks and for the potential to reduce environmental, health, and safety impacts associated with solvents. Quantitative models aid the development of large-area and roll-to-roll CVD polymer reactors. Relevant background, fundamental principles, and selected applications are reviewed.

  8. Formation of ordered mesoporous films from in situ structure inversion of azo polymer colloidal arrays.

    PubMed

    Li, Yaobang; Tong, Xiaolan; He, Yaning; Wang, Xiaogong

    2006-02-22

    This work shows that mesoporous polymeric films with spherical and elliptical pores can be obtained by in situ structure inversion of the azo polymer colloid arrays through selective interaction with solvent. The epoxy-based azo polymer contained both the pseudo-stilbene-type azo chromophores and the hydrophilic carboxyl groups. The colloidal spheres of the azo polymer were prepared by gradual hydrophobic aggregation of the polymeric chains in THF-H2O media, induced by a steady increase in the water content. Ordered 2D arrays of the hexagonally close-packed colloidal spheres were obtained by the vertical deposition method. After the solvent (THF) annealing, the ordered 2D arrays were directly transformed to mesoporous films through the sphere-pore inversion. Under the same condition, the 2D arrays composed of the ellipsoidal colloids, which were obtained by the irradiation of a polarized Ar+ laser beam on the colloidal sphere arrays, could be transformed to films with ordered elliptical pores. To our knowledge, this is the first example to demonstrate that mesoporous structures can be directly formed from the colloidal arrays of a homopolymer through structure inversion. This observation can shed new light on the nature of self-assembly processes and provide a feasible approach to fabricate mesoporous structures without the infiltration-removal step. By exploring the photoresponsive properties of the materials, mesoporous film with special pore structure and properties can be expected.

  9. Release and Skin Permeation of Scopolamine From Thin Polymer Films in Relation to Thermodynamic Activity.

    PubMed

    Kunst, Anders; Lee, Geoffrey

    2016-04-01

    The object was to demonstrate if the diffusional flux of the drug out of a drug-in-adhesive-type matrix and its subsequent permeation through an excised skin membrane is a linear function of the drug's thermodynamic activity in the thin polymer film. The thermodynamic activity, ap(*), is defined here as the degree of saturation of the drug in the polymer. Both release and release/permeation of scopolamine base from 3 different poylacrylate pressure-sensitive adhesives (PSAs) were measured. The values for ap(*) were calculated using previous published saturation solubilities, wp(s), of the drug in the PSAs. Different rates of release and release/permeation were determined between the 3 PSAs. These differences could be accounted for quantitatively by correlating with ap(*) rather than the concentration of the drug in the polymer films. At similar values for ap(*) the same release or release/permeation rates from the different polymers were measured. The differences could not be related to cross-linking or presence of ionizable groups of the polymers that should influence diffusivity.

  10. Nanoparticles of conjugated polymers prepared from phase-separated films of phospholipids and polymers for biomedical applications.

    PubMed

    Yoon, Jungju; Kwag, Jungheon; Shin, Tae Joo; Park, Joonhyuck; Lee, Yong Man; Lee, Yebin; Park, Jonghyup; Heo, Jung; Joo, Chulmin; Park, Tae Jung; Yoo, Pil J; Kim, Sungjee; Park, Juhyun

    2014-07-09

    Phase separation in films of phospholipids and conjugated polymers results in nanoassemblies because of a difference in the physicochemical properties between the hydrophobic polymers and the polar lipid heads, together with the comparable polymer side-chain lengths to lipid tail lengths, thus producing nanoparticles of conjugated polymers upon disassembly in aqueous media by the penetration of water into polar regions of the lipid heads.

  11. Controlled antiseptic release by alginate polymer films and beads.

    PubMed

    Liakos, Ioannis; Rizzello, Loris; Bayer, Ilker S; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-30

    Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca(2+)-cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants.

  12. Confinement of surface patterning in azo-polymer thin films.

    PubMed

    Yager, Kevin G; Barrett, Christopher J

    2007-03-07

    Azobenzene polymer thin films are known to spontaneously generate surface patterns in response to incident light gradients. This peculiar process is investigated in terms of the dynamics of the various azobenzene photomotions, which occur on different length scales. In particular, the formation and thermal erasure of surface relief gratings are measured as a function of film thickness and by using combinatorial samples with thickness gradients. The thermal erasure of gratings in this system provides a direct measure of the glass-transition temperature, which is found to deviate substantially from the bulk value. Thin azo films exhibit a glass transition up to 50 K higher than the bulk. These dynamical measurements allow the authors to probe the length scale of mass transport, which is found to be approximately 150 nm. Furthermore, surface mass transport is completely arrested in thin films<40 nm. According to these results, mass transport involves the coordinated motion of many polymer chains in the depth of the sample, rather than surface diffusion of individual chains.

  13. Electrochemically polymerized conjugated polymer films: Stability improvement and surface functionalization

    NASA Astrophysics Data System (ADS)

    Wei, Bin

    Conjugated polymers have been widely used in various applications including organic solar cells, electrochromic devices, chemical sensors, and biomedical devices. Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have received considerable interest because of their low oxidation potential, relatively high chemical stability, and high conductivity. Electrochemical deposition is a convenient method for precisely fabricating conjugated polymer thin films. Here, we report the stability improvement and surface functionalization of electrochemically polymerized PEDOT films. The long-term performance of PEDOT coatings is limited by their relatively poor stability on various inorganic substrates. Two different methods were used to improve the stability of PEDOT coatings, one involved using carboxylic acid functionalized EDOT (EDOT-acid) as adhesion promoter. EDOT-acid molecules were chemically bonded onto activated metal oxide substrates via chemisorption. PEDOT was then polymerized onto the EDOT-acid modified substrates, forming covalently bonded coatings. An aggressive ultrasonication test confirmed the significantly improved adhesion of the PEDOT films on electrodes with EDOT-acid treatment over those without treatment. The other method was to use an octa-ProDOT-functionalized POSS derivative (POSSProDOT) as cross-linker. PEDOT copolymer films were electrochemically deposited with various concentrations of POSS-ProDOT. The optical, morphological and electrochemical properties of the copolymer films could be systematically tuned with the incorporation of POSS-ProDOT. Significantly enhanced electrochemical and mechanical stability of the copolymers were observed at intermediate levels of POSS-ProDOT content (3.1 wt%) via chronic stimulation tests. Surface functionalization of conducting polymer films provides a potential means for systematically tailoring their chemical and physical properties. We have synthesized, polymerized and characterized a dialkene

  14. Glass transition dynamics of stacked thin polymer films

    NASA Astrophysics Data System (ADS)

    Fukao, Koji; Terasawa, Takehide; Oda, Yuto; Nakamura, Kenji; Tahara, Daisuke

    2011-10-01

    The glass transition dynamics of stacked thin films of polystyrene and poly(2-chlorostyrene) were investigated using differential scanning calorimetry and dielectric relaxation spectroscopy. The glass transition temperature Tg of as-stacked thin polystyrene films has a strong depression from that of the bulk samples. However, after annealing at high temperatures above Tg, the stacked thin films exhibit glass transition at a temperature almost equal to the Tg of the bulk system. The α-process dynamics of stacked thin films of poly(2-chlorostyrene) show a time evolution from single-thin-film-like dynamics to bulk-like dynamics during the isothermal annealing process. The relaxation rate of the α process becomes smaller with increase in the annealing time. The time scale for the evolution of the α dynamics during the annealing process is very long compared with that for the reptation dynamics. At the same time, the temperature dependence of the relaxation time for the α process changes from Arrhenius-like to Vogel-Fulcher-Tammann dependence with increase of the annealing time. The fragility index increases and the distribution of the α-relaxation times becomes smaller with increase in the annealing time for isothermal annealing. The observed change in the α process is discussed with respect to the interfacial interaction between the thin layers of stacked thin polymer films.

  15. The local segmental dynamics of polymer thin films

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Casalini, Riccardo; Prevosto, Daniele; Labardi, Massimiliano; Zhu, Lei; Baer, Eric

    The local segmental dynamics of poly(methyl methacrylate) (PMMA) in multi-layered films with polycarbonate was investigated using dielectric spectroscopy. The segmental relaxation time decreased with layer thickness down to 4 nm. However, two measures of the cooperativity of the dynamics, the breadth of the relaxation dispersion and the dynamic correlation volume, were unaffected by the film thickness. This absence of an effect of geometric confinement on the cooperativity, even when the confinement length scale approaches the correlation length scale, requires an asymmetric correlation volume; i.e., correlating regions having a string-like nature. To further probe the effect of layering on the segmental dynamics, we measured the segmental dynamics of poly(vinylacetate) thin films in contact with variously an aluminum interface, an incompatible polymer, and air (free surface). From local dielectric relaxation measurements using an AFM tip, the dynamics were observed to be faster in all thin film configurations compared to the bulk. However, no differences were observed for the various interfaces; capping the thin films with a rigid material accelerated the segmental motions equivalently to that for an air interface. This insensitivity of the dynamics to the nature of the interface affords a means to engineer thin films while maintaining desired mechanical properties. Work at NRL supported by the Office of Naval Research.

  16. Polymer nanocomposite films with extremely high nanoparticle loadings via capillary rise infiltration (CaRI)

    NASA Astrophysics Data System (ADS)

    Huang, Yun-Ru; Jiang, Yijie; Hor, Jyo Lyn; Gupta, Rohini; Zhang, Lei; Stebe, Kathleen J.; Feng, Gang; Turner, Kevin T.; Lee, Daeyeon

    2014-12-01

    Polymer nanocomposite films (PNCFs) with extremely high concentrations of nanoparticles are important components in energy storage and conversion devices and also find use as protective coatings in various applications. PNCFs with high loadings of nanoparticles, however, are difficult to prepare because of the poor processability of polymer-nanoparticle mixtures with high concentrations of nanoparticles even at an elevated temperature. This problem is exacerbated when anisotropic nanoparticles are the desired filler materials. Here we report a straightforward method for generating PNCFs with extremely high loadings of nanoparticles. Our method is based on what we call capillary rise infiltration (CaRI) of polymer into a dense packing of nanoparticles. CaRI consists of two simple steps: (1) the preparation of a two-layer film, consisting of a porous layer of nanoparticles and a layer of polymer and (2) annealing of the bilayer structure above the temperature that imparts mobility to the polymer (e.g., glass transition of the polymer). The second step leads to polymer infiltration into the interstices of the nanoparticle layer, reminiscent of the capillary rise of simple fluid into a narrow capillary or a packing of granules. We use in situ spectroscopic ellipsometry and a three-layer Cauchy model to follow the capillary rise of polystyrene into the random network of nanoparticles. The infiltration of polystyrene into a densely packed TiO2 nanoparticle layer is shown to follow the classical Lucas-Washburn type of behaviour. We also demonstrate that PNCFs with densely packed anisotropic TiO2 nanoparticles can be readily generated by spin coating anisotropic TiO2 nanoparticles atop a polystyrene film and subsequently thermally annealing the bilayer film. We show that CaRI leads to PNCFs with modulus, hardness and scratch resistance that are far superior to the properties of films of the component materials. In addition, CaRI fills in cracks that may exist in the

  17. Polarization Raman Microscopic Study of Molecular Alignment Behavior in Liquid Crystal/Polymer Composite Films

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2005-12-01

    We clarified that the molecular alignment of aggregated polymers is partially synchronized with liquid crystal (LC) director reorientation in an LC/polymer composite film. The molecular alignment behavior in composite films with LC- and polymer-rich regions formed by photopolymerization-induced phase separation was investigated using polarization Raman spectral microscopy. Raman scattering intensity induced by aligned side chains of polymers in the LC-rich region changed with LC director reorientation when voltage was applied to the composite film. It was confirmed for the first time that polymers capable of movement are formed in the LC-rich region.

  18. 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.

  19. 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.

  20. Selectively Patterning Polymer Opal Films via Microimprint Lithography.

    PubMed

    Ding, Tao; Zhao, Qibin; Smoukov, Stoyan K; Baumberg, Jeremy J

    2014-11-01

    Large-scale structural color flexible coatings have been hard to create, and patterning color on them is key to many applications, including large-area strain sensors, wall-size displays, security devices, and smart fabrics. To achieve controlled tuning, a micro-imprinting technique is applied here to pattern both the surface morphology and the structural color of the polymer opal films (POFs). These POFs are made of 3D ordered arrays of hard spherical particles embedded inside soft shells. The soft outer shells cause the POFs to deform upon imprinting with a pre-patterned stamp, driving a flow of the soft polymer and a rearrangement of the hard spheres within the films. As a result, a patterned surface morphology is generated within the POFs and the structural colors are selectively modified within different regions. These changes are dependent on the pressure, temperature, and duration of imprinting, as well as the feature sizes in the stamps. Moreover, the pattern geometry and structural colors can then be further tuned by stretching. Micropattern color generation upon imprinting depends on control of colloidal transport in a polymer matrix under shear flow and brings many potential properties including stretchability and tunability, as well as being of fundamental interest.

  1. Selectively Patterning Polymer Opal Films via Microimprint Lithography

    PubMed Central

    Ding, Tao; Zhao, Qibin; Smoukov, Stoyan K; Baumberg, Jeremy J

    2014-01-01

    Large-scale structural color flexible coatings have been hard to create, and patterning color on them is key to many applications, including large-area strain sensors, wall-size displays, security devices, and smart fabrics. To achieve controlled tuning, a micro-imprinting technique is applied here to pattern both the surface morphology and the structural color of the polymer opal films (POFs). These POFs are made of 3D ordered arrays of hard spherical particles embedded inside soft shells. The soft outer shells cause the POFs to deform upon imprinting with a pre-patterned stamp, driving a flow of the soft polymer and a rearrangement of the hard spheres within the films. As a result, a patterned surface morphology is generated within the POFs and the structural colors are selectively modified within different regions. These changes are dependent on the pressure, temperature, and duration of imprinting, as well as the feature sizes in the stamps. Moreover, the pattern geometry and structural colors can then be further tuned by stretching. Micropattern color generation upon imprinting depends on control of colloidal transport in a polymer matrix under shear flow and brings many potential properties including stretchability and tunability, as well as being of fundamental interest. PMID:26167447

  2. Water-Resistant and Transparent Plastic Films from Functionalizable Organic Polymers: Coordination Polymers as Templates for Solid-State [2+2]-Photopolymerization.

    PubMed

    Garai, Mousumi; Biradha, Kumar

    2017-01-05

    An organic polymer containing cyclobutanes and amides as backbones and pyridyl groups as sidearms was synthesized by single-crystal-to-single-crystal (SCSC) [2+2]-photopolymerization in the coordination polymers (CPs) of diene. The diene molecule was photo-inactive in its crystals and formed a triply intertwined 1D-helical CP with Cd(NO3 )2 and Cu(NO3 )2 salts. The 1D-CP was transformed into a coordination polymer of organic polymers containing threefold interpenetrated 3D-networks of CdSO4 topology through a [2+2]-reaction in SCSC manner upon irradiation. The organic polymer was separated from its CPs and found to have an unusually high degree of polymerization for this type of reaction. Furthermore, the organic polymer was amenable for N-alkylation reactions such as methylation, propylation, and decylation. The formate salts of the organic polymer and the methylated polymer were shown to form plastic films with a combination of properties such as high transparency, tensile strengths, gas permeability, thermal stability, water-resistance, and resistance to other organic solvents. The methylated polymer was also able to capture chromate ions and anionic dyes from aqueous solutions.

  3. Polymer-assisted deposition of metal-oxide films.

    PubMed

    Jia, Q X; McCleskey, T M; Burrell, A K; Lin, Y; Collis, G E; Wang, H; Li, A D Q; Foltyn, S R

    2004-08-01

    Metal oxides are emerging as important materials for their versatile properties such as high-temperature superconductivity, ferroelectricity, ferromagnetism, piezoelectricity and semiconductivity. Metal-oxide films are conventionally grown by physical and chemical vapour deposition. However, the high cost of necessary equipment and restriction of coatings on a relatively small area have limited their potential applications. Chemical-solution depositions such as sol-gel are more cost-effective, but many metal oxides cannot be deposited and the control of stoichiometry is not always possible owing to differences in chemical reactivity among the metals. Here we report a novel process to grow metal-oxide films in large areas at low cost using polymer-assisted deposition (PAD), where the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of uniform metal-organic films. The latter feature makes it possible to grow simple and complex crack-free epitaxial metal-oxides.

  4. Dynamics of polymer film formation during spin coating

    SciTech Connect

    Mouhamad, Y.; Clarke, N.; Jones, R. A. L.; Geoghegan, M.; Mokarian-Tabari, P.

    2014-09-28

    Standard models explaining the spin coating of polymer solutions generally fail to describe the early stages of film formation, when hydrodynamic forces control the solution behavior. Using in situ light scattering alongside theoretical and semi-empirical models, it is shown that inertial forces (which initially cause a vertical gradient in the radial solvent velocity within the film) play a significant role in the rate of thinning of the solution. The development of thickness as a function of time of a solute-free liquid (toluene) and a blend of polystyrene and poly(methyl methacrylate) cast from toluene were fitted to different models as a function of toluene partial pressure. In the case of the formation of the polymer blend film, a concentration-dependent (Huggins) viscosity formula was used to account for changes in viscosity during spin coating. A semi-empirical model is introduced, which permits calculation of the solvent evaporation rate and the temporal evolution of the solute volume fraction and solution viscosity.

  5. A molecular scale perspective: Monte Carlo simulation for rupturing of ultra thin polymer film melts

    NASA Astrophysics Data System (ADS)

    Singh, Satya Pal

    2017-04-01

    Monte Carlo simulation has been performed to study the rupturing process of thin polymer film under strong confinement. The change in mean square displacement; pair correlation function; density distribution; average bond length and microscopic viscosity are sampled by varying the molecular interaction parameters such as the strength and the equilibrium positions of the bonding, non-bonding potentials and the sizes of the beads. The variation in mean square angular displacement χθ = [ < Δθ2 > - < Δθ>2 ] fits very well to a function of type y (t) = A + B *e-t/τ. This may help to study the viscous properties of the films and its dependence on different parameters. The ultra thin film annealed at high temperature gets ruptured and holes are created in the film mimicking spinodal dewetting. The pair correlation function and density profile reveal rich information about the equilibrium structure of the film. The strength and equilibrium bond length of finite extensible non-linear elastic potential (FENE) and non-bonding Morse potential have clear impact on microscopic rupturing of the film. The beads show Rouse or repetition motion forming rim like structures near the holes created inside the film. The higher order interaction as dipole-quadrupole may get prominence under strong confinement. The enhanced excluded volume interaction under strong confinement may overlap with the molecular dispersion forces. It can work to reorganize the molecules at the bottom of the scale and can imprint its signature in complex patterns evolved.

  6. 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.

  7. Electroless plating of honeycomb and pincushion polymer films prepared by self-organization.

    PubMed

    Yabu, Hiroshi; Hirai, Yuji; Shimomura, Masatsugu

    2006-11-07

    This report describes the fabrication and electroless plating of regular porous and pincushion-like polymer structures prepared by self-organization. Honeycomb-patterned films were prepared by simple casting of polymer solution under applied humid air and pincushion structures by peeling off the top layer of the former films. Silver-deposited honeycomb-patterned films and pincushion films were obtained by simple electroless plating of the respective original structures. XPS revealed Ag deposition on the honeycomb-patterned film. After thermal decomposition or solvent elution of the template polymer, unique metal mesoscopic structures were obtained.

  8. Thiophene polymer semiconductors for organic thin-film transistors.

    PubMed

    Ong, Beng S; Wu, Yiliang; Li, Yuning; Liu, Ping; Pan, Hualong

    2008-01-01

    Printed organic thin-film transistors (OTFTs) have received great interests as potentially low-cost alternative to silicon technology for application in large-area, flexible, and ultra-low-cost electronics. One of the critical materials for TFTs is semiconductor, which has a dominant impact on the transistor properties. We review here the structural studies and design of thiophene-based polymer semiconductors with respect to solution processability, ambient stability, molecular self-organization, and field-effect transistor properties for OTFT applications. We show that through judicial monomer design, delicately controlled pi-conjugation, and strategically positioned pendant side-chain distribution, novel solution-processable thiophene polymer semiconductors with excellent self-organization ability to form extended lamellar pi-stacking orders can be developed. OTFTs using semiconductors of this nature processed in ambient conditions have provided excellent field-effect transistor properties.

  9. Detection of Carbon Monoxide Using Polymer-Carbon Composite Films

    NASA Technical Reports Server (NTRS)

    Homer, Margie L.; Ryan, Margaret A.; Lara, Liana M.

    2011-01-01

    A carbon monoxide (CO) sensor was developed that can be incorporated into an existing sensing array architecture. The CO sensor is a low-power chemiresistor that operates at room temperature, and the sensor fabrication techniques are compatible with ceramic substrates. Sensors made from four different polymers were tested: poly (4-vinylpryridine), ethylene-propylene-diene-terpolymer, polyepichlorohydrin, and polyethylene oxide (PEO). The carbon black used for the composite films was Black Pearls 2000, a furnace black made by the Cabot Corporation. Polymers and carbon black were used as received. In fact, only two of these sensors showed a good response to CO. The poly (4-vinylpryridine) sensor is noisy, but it does respond to the CO above 200 ppm. The polyepichlorohydrin sensor is less noisy and shows good response down to 100 ppm.

  10. Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks

    SciTech Connect

    Zhang, L.; Zhou, J.; Huang, J.; Gong, P. Zhou, Q.; Zheng, L.; Du, Y.

    1999-11-01

    Interpenetrating polymer network (IPN) coatings synthesized from castor-oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80--100 C for 2--5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity-average molecular weight, M{sub {eta}}, and the weight of the degraded films decreased sharply with the progress of degradation. The degradation half-lifes, t{sub 1/2}, of the films in soil at 30 C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC {gt} RCNC {gt} RCCH {gt} RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO{sub 2} evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO{sub 2}, H{sub 2}O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.

  11. Generalized ellipsometry analysis of anisotropic nanoporous media: Polymer-infiltrated nanocolumnar and inverse-column polymeric films

    NASA Astrophysics Data System (ADS)

    Liang, Dan

    Characterization of the structural and optical properties is a subject of significance for nanoporous material research. However, it remains a challenge to find non-destructive methods for investigating the anisotropy of porous thin films with three-dimensional nanostructures. In this thesis, a generalized ellipsometry (GE) analysis approach is employed to study two types of anisotropic nanoporous media: slanted columnar thin films (SCTFs) with polymer infiltration and inverse-SCTF polymeric films. The thesis presents the physical properties obtained from GE analysis, including porosity, columnar shape, principal optical constants, birefringence, etc.. The thesis reports on using a GE analysis approach, combining the homogeneous biaxial layer approach (HBLA) and anisotropic Bruggeman effective medium approximation (AB-EMA), to determine the changes in structural and optical properties of highly porous SCTFs upon polymer infiltration. Via spin-coating, poly(-methyl methacrylate) (PMMA) was infiltrated into the permalloy SCTFs prepared by glancing angle deposition (GLAD). The Mueller matrix GE measurements were conducted on the SCTFs before and after PMMA infiltration. The obtained film thickness and columnar slanting angle show changes due to infiltration which are in good agreement with scanning electron microscopy (SEM) analysis. The method effectively identifies the changes in birefringence and dichroism upon infiltration, and provides constituent fractions consistent with the performed experiments. GE analysis is further utilized to characterize the biaxial optical responses of the porous polymer thin films. The porous polymer films with inverse columnar structure (PMMA iSCTFs) were prepared via infiltrating polymer into the voids of the SCTF templates and selectively removing the columns. The AB-EMA was employed to analyze the GE data of the porous polymer films and SCTF templates to determine the structural and anisotropic optical properties. The structural

  12. Analysis of Osteoblast Differentiation on Polymer Thin Films Embedded with Carbon Nanotubes.

    PubMed

    Lee, Jin Woo; Park, Jin-Woo; Khang, Dongwoo

    2015-01-01

    Osteoblast differentiation can be modulated by variations in order of nanoscale topography. Biopolymers embedded with carbon nanotubes can cause various orders of roughness at the nanoscale and can be used to investigate the dynamics of extracellular matrix interaction with cells. In this study, clear relationship between the response of osteoblasts to integrin receptor activation, their phenotype, and transcription of certain genes on polymer composites embedded with carbon nanotubes was demonstrated. We generated an ultrathin nanocomposite film embedded with carbon nanotubes and observed improved adhesion of pre-osteoblasts, with a subsequent increase in their proliferation. The expression of genes encoding integrin subunits α5, αv, β1, and β3 was significantly upregulated at the early of time-point when cells initially attached to the carbon nanotube/polymer composite. The advantage of ultrathin nanocomposite film for pre-osteoblasts was demonstrated by staining for the cytoskeletal protein vinculin and cell nuclei. The expression of essential transcription factors for osteoblastogenesis, such as Runx2 and Sp7 transcription factor 7 (known as osterix), was upregulated after 7 days. Consequently, the expression of genes that determine osteoblast phenotype, such as alkaline phosphatase, type I collagen, and osteocalcin, was accelerated on carbon nanotube embedded polymer matrix after 14 days. In conclusion, the ultrathin nanocomposite film generated various orders of nanoscale topography that triggered processes related to osteoblast bone formation.

  13. A study of the initial film growth of PEG-like plasma polymer films via XPS and NEXAFS

    NASA Astrophysics Data System (ADS)

    Li, Yali; Muir, Benjamin W.; Easton, Christopher D.; Thomsen, Lars; Nisbet, David R.; Forsythe, John S.

    2014-01-01

    The chemistry of substrate-film interface (underside) of di(ethylene glycol) dimethyl ether plasma polymer (DGpp) films has been studied directly and compared to the top layer of the film (topside). By depositing the plasma polymer films onto indium tin oxide (ITO) glass, the films were easily delaminated from the substrate. The top- and underside of the films were examined by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was found that a rapid increase in pressure during plasma polymerization results in steep chemical gradients in the films, while small pressure changes do not lead to chemical gradient formation. These observations validate the findings of previous neutron reflectometry modeling studies of this class of plasma polymer thin film. In addition, subtle variations in plasma polymer film chemistry were observed between different substrates they were deposited onto. This approach will allow additional studies on the mechanisms of early plasma polymer thin film formation with various monomers.

  14. Fiber-Optic Sensor Would Monitor Growth of Polymer Film

    NASA Technical Reports Server (NTRS)

    Beamesderfer, Michael

    2005-01-01

    A proposed optoelectronic sensor system would measure the increase in thickness of a film of parylene (a thermoplastic polymer made from para-xylene) during growth of the film in a vapor deposition process. By enabling real-time monitoring of film thickness, the system would make it possible to identify process conditions favorable for growth and to tailor the final thickness of the film with greater precision than is now possible. The heart of the sensor would be a pair of fiber-optic Fabry-Perot interferometers, depicted schematically in the figure. (In principle, a single such interferometer would suffice. The proposal calls for the use of two interferometers for protective redundancy and increased accuracy.) Each interferometer would include a light source, a fiber-optic coupler, and photodetectors in a control box outside the deposition chamber. A single-mode optical fiber for each interferometer would run from inside the control box to a fused-silica faceplate in a sensor head. The sensory tips of the optical fibers would be polished flush with the free surface of the faceplate. In preparation for use, the sensor head would be mounted with a hermetic seal in a feed-through port in the deposition chamber, such that free face of the faceplate and the sensory tips of the optical fibers would be exposed to the deposition environment. During operation, light would travel along each optical fiber from the control box to the sensor head. A small portion of the light would be reflected toward the control box from the end face of each fiber. Once growth of the parylene film started, a small portion of the light would also be reflected toward the control box from the outer surface of the film. In the control box, the two reflected portions of the light beam would interfere in one of the photodetectors. The difference between the phases of the interfering reflected portions of the light beam would vary in proportion to the increasing thickness of the film and the known

  15. High temperature polymer dielectric film-wire insulation

    NASA Technical Reports Server (NTRS)

    Nairus, John G.

    1994-01-01

    The highlights of the program are outlined including two major accomplishments. TRW identified and demonstrated the potential of two aromatic/heterocyclic polymers to have an outstanding and superior combination of electrical, thermal, and chemical resistance properties versus state-of-the-art Kapton for spacecraft and/or aircraft dielectric insulation applications. (Supporting data is provided in tables.) Feasibility was demonstrated for supporting/enabling technologies such as ceramic coatings, continuous film casting, and conductor wire wrapping, which are designed to accelerate qualification and deployment of the new wire insulation materials for USAF systems applications during the mid- to late-1990's.

  16. Probing opto-mechanical stresses within azobenzene-containing photosensitive polymer films by a thin metal film placed above.

    PubMed

    Yadavalli, Nataraja Sekhar; Korolkov, Denis; Moulin, Jean-François; Krutyeva, Margarita; Santer, Svetlana

    2014-07-23

    Azo-modified photosensitive polymers offer the interesting possibility to reshape bulk polymers and thin films by UV-irradiation while being in the solid glassy state. The polymer undergoes considerable mass transport under irradiation with a light interference pattern resulting in the formation of surface relief grating (SRG). The forces inscribing this SRG pattern into a thin film are hard to assess experimentally directly. In the current study, we are proposing a method to probe opto-mechanical stresses within polymer films by characterizing the mechanical response of thin metal films (10 nm) deposited on the photosensitive polymer. During irradiation, the metal film not only deforms along with the SRG formation but ruptures in a regular and complex manner. The morphology of the cracks differs strongly depending on the electrical field distribution in the interference pattern, even when the magnitude and the kinetics of the strain are kept constant. This implies a complex local distribution of the opto-mechanical stress along the topography grating. In addition, the neutron reflectivity measurements of the metal/polymer interface indicate the penetration of a metal layer within the polymer, resulting in a formation of a bonding layer that confirms the transduction of light-induced stresses in the polymer layer to a metal film.

  17. Photochromism and diffraction grating in cyanoazobenzene polymer films

    NASA Astrophysics Data System (ADS)

    Serwadczak, M.; Wübbenhorst, M.; Kucharski, S.

    2006-08-01

    Two series of photochromic copolymathacrylates containing cyanoazobenzene chromophores as side chains were described. The series with shorter ethylene spacer between mesogen and main polymethacrylate chain was amorphous, whereas the second one with longer ethoxyethylene spacer was liquid crystalline forming smectic C mesophase above Tg. The materials were deposited on glass substrates via spin coating and casting technique to provide thin transparent films. The reversible change of refractive index of the films on illumination with white light was determined by ellipsometry. The difference of real part of the refractive index of the sample was in the range 0.0067-0.0210 depending on the polymer. Formation of diffraction grating was achieved by two beam coupling arrangement using a 532 nm laser diode . The diffraction efficiency for the first order diffraction was in the range of 1.5-2.1% for the homopolymers.

  18. Soap opera : polymer-surfactant interactions on thin film surfaces /

    SciTech Connect

    Ozer, B. H.; Johal, M. S.; Wang, H. L.; Robinson, J. M.

    2001-01-01

    Surfactants are macromolecules with unique properties. They commonly contain a polar head group with a nonpolar hydrocarbon chain. These properties allow surfactants to solubilize greases and other nonpolar molecules. One particular way that this is accomplished is through the formation of micelles. Micelles are formed at the critical micelle concentration (cmc), which varies depending upon the nature of the surfactant and also the media in which the surfactant resides. These micelles can take a variety of shapes, but are generally characterized by surrounding the grease with the nonpolar hydrocarbon chains, exposing only the polarized head groups to the media, usually water. This property of easy solubilization has made surfactants a very attractive industrial agent, They are used most conventionally as industrial cleaning agents and detergents. However, they also have lesser-known applications in conjunction with polymers and other macromolecular mixtures, often creating a system with novel properties, such as increased solubilization and smoother mixture consistency. A recently developed field has investigated the self-assembly of polymers and polyelectrolytes onto thin film surfaces. There are many reasons for studying this process, such as for second harmonic generation purposes and bioassays. In this study, the interaction between the anionic polyelectrolyte poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and two surfactants of opposite charge, Sodium Dodecyl Sulfate (SDS) and Dodecyl Trimethyl Ammonium Bromide (DTAB), in their assembly onto thin film surfaces was investigated. The kinetics of adsorbance onto the thin films was examined, followed by construction of 10-bilayer films using an alternating layer of the cationic polyelectrolyte poly(ethylenimine) (PEI) to provide the electrostatic means for the PAZO/surfactant combination to assemble onto the thin film. The kinetics of adsorption is being

  19. Adhesion between polymers and evaporated gold and nickel films

    NASA Technical Reports Server (NTRS)

    Yamada, Y.; Wheeler, D. R.; Buckley, D. H.

    1984-01-01

    To obtain information on the adhesion between metal films and polymeric solids, the adhesion force was measured by means of a tensile pull test. It was found that the adhesion strengths between polymeric solids and gold films evaporated on polymer substrates were (1.11 + or - 0.53) multiplied by 10(6) N/M(2) on PTFE, about 5.49 multiplied by 10(6) N/m(2) on UHMWPE, and 6.54x10(6) on 6/6 nylon. The adhesion strengths for nickel films evaporated on PTFE, UHMWPE, and 6/6 nylon were found to be a factor of 1.7 higher than those for the gold coated PTFE, UHMWPE, and 6/6 nylon. To confirm quantitatively the effect of electron irradiation on the adhesion strength between a PTFE solid and metal films, a tensile pull test was performed on the irradiated PTFE specimens, which were prepared by evaporating nickel or gold on PTFE surfaces irradiated by 2-keV electrons for various times. After irradiation, the adhesion strength increased to (4.92 + or - 0.92)x10(6) N/m(2) for nickel coated PTFE and (1.82 + or - 0.48)x10(6) N/m(2) for gold coated PTFE. The improvement in adhesion for nickel is higher than that for gold.

  20. Hybrid Thin Films Based Upon Polyoxometalates-Polymer Assembly

    NASA Astrophysics Data System (ADS)

    Qi, Na; Jing, Benxin; Zhu, Yingxi

    2014-03-01

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

  1. Numerical simulations of electrohydrodynamic evolution of thin polymer films

    NASA Astrophysics Data System (ADS)

    Borglum, Joshua Christopher

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

  2. Solid mesostructured polymer-surfactant films at the air-liquid interface.

    PubMed

    Pegg, Jonathan C; Eastoe, Julian

    2015-08-01

    Pioneering work by Edler et al. has spawned a new sub-set of mesostructured materials. These are solid, self-supporting films comprising surfactant micelles encased within polymer hydrogel; composite polymer-surfactant films can be grown spontaneously at the air-liquid interface and have defined and controllable mesostructures. Addition of siliconalkoxide to polymer-surfactant mixtures allows for the growth of mesostructured hybrid polymer-surfactant silica films that retain film geometry after calcinations and exhibit superior mechanical properties to typically brittle inorganic films. Growing films at the air-liquid interface provides a rapid and simple means to prepare ordered solid inorganic films, and to date the only method for generating mesostructured films thick enough (up to several hundred microns) to be removed from the interface. Applications of these films could range from catalysis to encapsulation of hydrophobic species and drug delivery. Film properties and mesostructures are sensitive to surfactant structure, polymer properties and polymer-surfactant phase behaviour: herein it will be shown how film mesostructure can be tailored by directing these parameters, and some interesting analogies will be drawn with more familiar mesostructured silica materials.

  3. Film type SO-168 radiation study

    NASA Technical Reports Server (NTRS)

    Pierce, W. N.

    1972-01-01

    Investigations were performed to determine optimum exposure and processing procedures necessary to partially offset the effect of radiation to which film type SO-168 will be exposed during the Skylab Mission. This task became necessary when it was determined that original predictions of 2 to 3 RADS of radiation to which the film will be exposed were too low, and that levels as high as 3.5 to 4.0 RADS may be incurred, thus reducing image quality below an acceptable level. Tests results show that forced processing of type SO-168 film tended to reduce the density range to an unusable level, and that processing to a lower ASA value would provide greater image quality for the user.

  4. Effect of polymer/clay composition on processability of polylactide nanocomposites by film blowing

    NASA Astrophysics Data System (ADS)

    Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Di Maio, L.; Incarnato, L.

    2015-12-01

    The blown extrusion of poly(lactic acid) presents several challenges mainly due to its poor elongation properties. This work deals on the possibility to enhance the processabiliy of PLA by film blowing by functionalizing the polymer with nanosilicates. In particular, two types of polylactic acid (PLA 4032D and PLA 4042D) and different types of filler, selected from montmorillonites (Cloisite 30B) and bentonites (Nanofil SE3010) families, were used to prepare the hybrid systems by using a twin-screw extruder. The interaction between the polymer and the clay was evaluated by FTIR analysis and correlated to the structure of the obtained nanocomposites in terms of clay dispersion. All the samples were then submitted to rheological measurements both in shear and elongational mode.

  5. High Temperature Polymer Film Dielectrics for Aerospace Power Conditioning Capacitor Applications

    DTIC Science & Technology

    2008-10-01

    AFRL-RZ-WP-TP-2010-2128 HIGH TEMPERATURE POLYMER FILM DIELECTRICS FOR AEROSPACE POWER CONDITIONING CAPACITOR APPLICATIONS (Postprint...AND SUBTITLE HIGH TEMPERATURE POLYMER FILM DIELECTRICS FOR AEROSPACE POWER CONDITIONING CAPACITOR APPLICATIONS (Postprint) 5a. CONTRACT NUMBER...development of compact capacitors which are thermally robust for operation in a variety of aerospace power conditioning applications. While such applications

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

    PubMed

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

    2015-02-11

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

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

    SciTech Connect

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

    1995-09-06

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

  8. The relationship between film formation and anti-corrosive properties of latex polymers

    SciTech Connect

    Satguru, R.; Padget, J.C.

    1995-12-31

    The emphasis of the paper would be to demonstrate the importance of coherent film formation to derive superior anti-corrosive coatings. The principles of film formation of solvent borne polymer in comparison with waterborne dispersed polymer will be discussed. Two examples of latex polymers will then be presented highlighting the influence of additives such as surfactant and coalescing agent on the film formation process. The examples will include a chloropolymer latex and a styrene-acrylic polymer latex. Results from Electron Microscopy, Atomic Force Microscopy, Moisture Vapour Transmission Measurement, A/C Impedance Measurement, Hot Salt Spray Performance, etc. will be presented.

  9. Laser Ablative Deposition of Polymer Films: A Promise for Sensor Fabrication

    NASA Astrophysics Data System (ADS)

    Blazevska-Gilev, Jadranka; Kupčík, Jaroslav; Šubrt, Jan; Pola, Josef

    There is a continuing interest in the use of polymer films as insulating components of sensors; a number of such films have been prepared by polymer sputtering or vacuum deposition processes involving gas phase pyrolysis/photolysis and by plasma decomposition of monomers. An attractive and rather new technique for the deposition of novel polymer films is IR laser ablation of polymers containing polar groups. We have recently studied this process with poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and poly(vinyl chloride-co-vinyl acetate) P(VC/VAc) to establish its specific features and differences to conventional pyrolysis.

  10. Slippage and nanorheology of thin liquid polymer films

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  11. Impact of polymer film thickness and cavity size on polymer flow during embossing : towards process design rules for nanoimprint lithography.

    SciTech Connect

    Schunk, Peter Randall; King, William P. (Georgia Institute of Technology, Atlanta, GA); Sun, Amy Cha-Tien; Rowland, Harry D.

    2006-08-01

    This paper presents continuum simulations of polymer flow during nanoimprint lithography (NIL). The simulations capture the underlying physics of polymer flow from the nanometer to millimeter length scale and examine geometry and thermophysical process quantities affecting cavity filling. Variations in embossing tool geometry and polymer film thickness during viscous flow distinguish different flow driving mechanisms. Three parameters can predict polymer deformation mode: cavity width to polymer thickness ratio, polymer supply ratio, and Capillary number. The ratio of cavity width to initial polymer film thickness determines vertically or laterally dominant deformation. The ratio of indenter width to residual film thickness measures polymer supply beneath the indenter which determines Stokes or squeeze flow. The local geometry ratios can predict a fill time based on laminar flow between plates, Stokes flow, or squeeze flow. Characteristic NIL capillary number based on geometry-dependent fill time distinguishes between capillary or viscous driven flows. The three parameters predict filling modes observed in published studies of NIL deformation over nanometer to millimeter length scales. The work seeks to establish process design rules for NIL and to provide tools for the rational design of NIL master templates, resist polymers, and process parameters.

  12. Coupled effects of substrate adhesion and intermolecular forces on polymer thin film glass-transition behavior.

    PubMed

    Xia, Wenjie; Keten, Sinan

    2013-10-15

    Intermolecular noncovalent forces between polymer chains influence the mobility and glass-transition temperature (Tg), where weaker interchain interactions, all else being the same, typically results in lower bulk polymer Tg. Using molecular dynamics simulations, here we show that this relation can become invalid for supported ultrathin films when the substrate-polymer interaction is extremely strong and the polymer-polymer interactions are much weaker. This contrasting trend is found to be due to a more pronounced substrate-induced appreciation of the film Tg for polymers with weaker intermolecular interactions and low bulk Tg. We show that optimizing this coupling between substrate adhesion and bulk Tg maximizes thin film Tg, paving the way for tuning film properties through interface nanoengineering.

  13. Simulation of bipolar charge transport in nanocomposite polymer films

    NASA Astrophysics Data System (ADS)

    Lean, Meng H.; Chu, Wei-Ping L.

    2015-03-01

    This paper describes 3D particle-in-cell simulation of bipolar charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix. The classical electrical double layer (EDL) model for a monopolar core is extended (eEDL) to represent the nanofiller by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles migrate via field-dependent Poole-Frenkel mobility and recombine with Monte Carlo selection. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. The model is capable of simulating a wide dynamic range spanning leakage current to pre-breakdown. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix indicate that charge transport behavior depend on nanoparticle polarization with anti-parallel orientation showing the highest leakage conduction and therefore lowest level of charge trapping in the interaction zone. Charge recombination is also highest, at the cost of reduced leakage conduction charge. The eEDL model predicts the meandering pathways of charge particle trajectories.

  14. Modeling thin-film piezoelectric polymer ultrasonic sensors.

    PubMed

    González, M G; Sorichetti, P A; Santiago, G D

    2014-11-01

    This paper presents a model suitable to design and characterize broadband thin film sensors based on piezoelectric polymers. The aim is to describe adequately the sensor behavior, with a reasonable number of parameters and based on well-known physical equations. The mechanical variables are described by an acoustic transmission line. The electrical behavior is described by the quasi-static approximation, given the large difference between the velocities of propagation of the electrical and mechanical disturbances. The line parameters include the effects of the elastic and electrical properties of the material. The model was validated with measurements of a poly(vinylidene flouride) sensor designed for short-pulse detection. The model variables were calculated from the properties of the polymer at frequencies between 100 Hz and 30 MHz and at temperatures between 283 K and 313 K, a relevant range for applications in biology and medicine. The simulations agree very well with the experimental data, predicting satisfactorily the influence of temperature and the dielectric properties of the polymer on the behavior of the sensor. Conversely, the model allowed the calculation of the material dielectric properties from the measured response of the sensor, with good agreement with the published values.

  15. IR laser welding of thin polymer films as a fabrication method for polymer MEMS

    NASA Astrophysics Data System (ADS)

    Beck, William A.; Huang, Michelle; Ketterl, Joe; Hughes, Thayer

    2003-09-01

    MEMS (Micro Electro-Mechanical Systems) continue to be something of a solution looking for a problem. Even as the glamour has moved on to the smaller realm of nano technologies and devices, progress continues towards making micro-scale devices more useful and manufacturable. One avenue this work is taking is into the realm of polymer MEMS, shifting from the expensive, complicated methods of semiconductor processing to the much simpler methods of plastics processing. Polymeric materials are rugged, lightweight and low cost, and their use in manufacturing has a long history. While many bulk polymer manufacturing processes such as molding, machining and adhesive bonding are adaptable to the micro realm, their use in MEMS devices often requires development of specialized processing methods. Here we report on development of laser welding as a bonding method for thin polymer films, including automation of the welding process, steps towards standardization of that process, preparation of standardized test samples, and development of specialized test methods used to evaluate the strength of polymer welds. Our initial results show a direct correlation between welding parameters and weld strengths.

  16. Electrochemical route to fabricate film-like conjugated microporous polymers and application for organic electronics.

    PubMed

    Gu, Cheng; Chen, Youchun; Zhang, Zhongbo; Xue, Shanfeng; Sun, Shuheng; Zhang, Kai; Zhong, Chengmei; Zhang, Huanhuan; Pan, Yuyu; Lv, Ying; Yang, Yanqin; Li, Fenghong; Zhang, Suobo; Huang, Fei; Ma, Yuguang

    2013-07-05

    Film-like conjugated microporous polymers (CMPs) are fabricated by the novel strategy of carbazole-based electropolymerization. The CMP film storing a mass of counterions acting as an anode interlayer provides a significant power-conversion efficiency of 7.56% in polymer solar cells and 20.7 cd A(-1) in polymer light-emitting diodes, demonstrating its universality and potential as an electrode interlayer in organic electronics.

  17. Tracking polymer diffusion in a wet latex film with fluorescence resonance energy transfer.

    PubMed

    Haley, Jeffrey C; Liu, Yuanqin; Winnik, Mitchell A; Demmer, David; Haslett, Tom; Lau, Willie

    2007-08-01

    We describe an instrument to measure the polymer interdiffusion between donor-labeled and acceptor-labeled latex polymers in a partially wet latex film with fluorescence resonance energy transfer (FRET). It is possible to temporarily arrest the drying process of a wet latex film by sealing the film in an airtight chamber. In our approach, we measure donor fluorescence decays from 0.5 mm diameter spots at various positions across an arrested latex film with time-correlated single photon counting. We interpret the resulting decays with a Monte Carlo simulation of the FRET process and extract information about the extent of polymer diffusion as a function of position on the film. These results enable us to determine the extent of polymer interdiffusion as a function of distance from the wet-dry edge in the latex film. To highlight this device's ability to capture the rapid early stages of latex interdiffusion, we report results from an acrylate copolymer latex.

  18. Formation and performance of polymer dispersed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Chan, Philip Kwok-Kiou

    Polymer dispersed liquid crystals (PDLC's) are novel composite materials consisting of micron-size liquid crystalline droplets dispersed uniformly in a solid polymer matrix. PDLC's are formed by spinodal decomposition induced by thermal quenching or polymerization. These materials have excellent magneto-optical properties, and have great potential in applications that require efficient light scattering. Present commercial applications include switchable windows for privacy control and large-scale billboards. The optical properties depend on the droplet size, shape and positional order, which are determined during the formation stage, and reorientation dynamics of the liquid crystalline molecules confined within the droplets which occurs during product use. In this thesis, new complex mathematical models that describe the formation and performance of PDLC's are successfully developed, implemented, solved and validated. The nonequilibrium thermodynamic formation model takes into account initial thermal fluctuations computed using Monte Carlo simulations and realistic arbitrary boundary conditions. The performance model is based on classical nematic liquid crystalline magneto-viscoelastic theories, and incorporates transient viscoelastic boundary conditions. The simulations are able to reproduce successfully all the experimentally observed significant dynamical and morphological features of film formation as well as all the dynamical stages observed during the use of these thin optical films. In addition, the sensitivity of the phase separating morphology to processing conditions and material parameters is elucidated. Furthermore, a new scaling method is introduced to describe the phase separation phenomena during the early and intermediate stages of spinodal decomposition induced by thermal quenching. The droplet size selection mechanism for the polymerization-induced phase separation method of forming PDLC films is identified and explained for the first time. Lastly

  19. Experimental study of the polymer powder film thickness uniformity produced by the corona discharge

    NASA Astrophysics Data System (ADS)

    Fazlyyyakhmatov, Marsel

    2017-01-01

    The results of an experimental study of the polymer powder film thickness uniformity are presented. Polymer powder films are produced by the electrostatic field of corona discharge. Epoxy and epoxy-polyester powder films with thickness in the range of 30-120 microns are studied. Experimentally confirmed possibility of using these coatings as protective matching layer of piezoceramic transducers at frequencies of 0.5-15 MHz.

  20. Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors

    DTIC Science & Technology

    2009-07-01

    Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors by Janet Ho and Richard Jow ARL-TR-4880 July...TR-4880 July 2009 Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors Janet Ho and Richard Jow...Films for Power Conditioning Capacitors 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 6. AUTHOR(S) Janet Ho and Richard Jow 5f

  1. Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films

    NASA Astrophysics Data System (ADS)

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

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

  2. Prism coupling technique investigation of elasto-optical properties of thin polymer films

    NASA Astrophysics Data System (ADS)

    Ay, Feridun; Kocabas, Askin; Kocabas, Coskun; Aydinli, Atilla; Agan, Sedat

    2004-12-01

    The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three different polymers; polystyrene, polymethyl-methacrylate, and benzocyclobutane. The out-of-plane elastic modulus, refractive index, film thickness, and birefringence of thin polymer films were determined by means of the prism coupling technique. The effect of the applied stress on the refractive index and birefringence of the films was investigated. Three-dimensional finite element method analysis was used so as to obtain the principal stresses for each polymer system, and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined. It was found that the applied stress in the out-of-plane direction of the thin films investigated leads to negative elasto-optic coefficients, as observed for all the three thin polymer films.

  3. ITO-MgF2 Film Development for PowerSphere Polymer Surface Protection

    NASA Technical Reports Server (NTRS)

    Hambourger, Paul D.; Kerslake, Thomas W.; Waters, Deborah L.

    2004-01-01

    Multi-kilogram class microsatellites with a PowerSphere electric power system are attractive for fulfilling a variety of potential NASA missions. However, PowerSphere polymer surfaces must be coated with a film that has suitable electrical sheet resistivity for electrostatic discharge control, be resistant to atomic oxygen attack, be transparent to ultraviolet light for composite structure curing and resist ultraviolet light induced darkening for efficient photovoltaic cell operation. In addition, the film must be tolerant of polymer layer folding associated with launch stowage of PowerSphere inflatable structures. An excellent film material candidate to meet these requirements is co-sputtered, indium oxide (In2O3) - tin oxide (SnO2), known as 'ITO', and magnesium fluoride (MgF2). While basic ITO-MgF2 film properties have been the subject of research over the last decade, further research is required in the areas of film durability for space-inflatable applications and precise film property control for large scale commercial production. In this paper, the authors present film durability results for a folded polymer substrate and film resistance to vacuum UV darkening. The authors discuss methods and results in the area of film sheet resistivity measurement and active control, particularly dual-channel, plasma emission line measurement of ITO and MgF2 plasma sources. ITO-MgF2 film polymer coupon preparation is described as well as film deposition equipment, procedures and film characterization. Durability testing methods are also described. The pre- and post-test condition of the films is assessed microscopically and electrically. Results show that an approx. 500A ITO-18vol% MgF2 film is a promising candidate to protect PowerSphere polymer surfaces for Earth orbit missions. Preliminary data also indicate that in situ film measurement methods are promising for active film resistivity control in future large scale production. Future film research plans are also

  4. High Seebeck effects from conducting polymer: Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) based thin-film device with hybrid metal/polymer/metal architecture

    SciTech Connect

    Stanford, Michael G; Wang, Hsin; Ivanov, Ilia N; Hu, Bin

    2012-01-01

    Conductive polymers are of particular interest for thermoelectric applications due to their low thermal conductivity and relatively high electrical conductivity. In this study, commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used in a hybrid metal/polymer/metal thin film design in order to achieve a high Seebeck coefficient with the value of 252lV/k on a relatively low temperature scale. Polymer film thickness was varied in order to investigate its influence on the Seebeck effect. The high Seebeck coefficient indicates that the metal/polymer/metal design can develop a large entropy difference in internal energy of charge carriers between high and low-temperature metal electrodes to develop electrical potential due to charge transport in conducting polymer film through metal/polymer interface. Therefore, the metal/polymer/metal structure presents a new design to combine inorganic metals and organic polymers in thin-film form to develop Seebeck devices

  5. Optimization of VO2 nanowire polymer composite thermochromic films by optical simulation

    NASA Astrophysics Data System (ADS)

    Naoi, Yuki; Amano, Jun

    2016-12-01

    Thermochromic films with high efficiency, transparency, and flexibility are highly desirable for energy-efficient smart window films. Vanadium oxide (VO2)-nanoparticle-embedded flexible polymer composite films are the most promising thermochromic films because of the sharp phase transition of insulating to metallic phases of VO2 at 68 °C with visible transparency and a large change in transmittance at near-infrared wavelengths before and after the metal-insulator phase transition. This paper describes the simulation of high-efficiency thermochromic polymer composite films embedded with VO2 nanoparticles of various sizes to investigate the optimum VO2 nanowire size and length.

  6. Layered conductive polymer on nylon membrane templates for high performance, thin-film supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Shi, HaoTian Harvey; Naguib, Hani E.

    2016-04-01

    Flexible Thin-film Electrochemical Capacitors (ECs) are emerging technology that plays an important role as energy supply for various electronics system for both present era and the future. Intrinsically conductive polymers (ICPs) are promising pseudo-capacitive materials as they feature both good electrical conductivity and high specific capacitance. This study focuses on the construction and characterization of ultra-high surface area porous electrodes based on coating of nano-sized conductive polymer materials on nylon membrane templates. Herein, a novel nano-engineered electrode material based on nylon membranes was presented, which allows the creation of super-capacitor devices that is capable of delivering competitive performance, while maintaining desirable mechanical characteristics. With the formation of a highly conductive network with the polyaniline nano-layer, the electrical conductivity was also increased dramatically to facilitate the charge transfer process. Cyclic voltammetry and specific capacitance results showed promising application of this type of composite materials for future smart textile applications.

  7. 3D tissue culture substrates produced by microthermoforming of pre-processed polymer films.

    PubMed

    Giselbrecht, S; Gietzelt, T; Gottwald, E; Trautmann, C; Truckenmüller, R; Weibezahn, K F; Welle, A

    2006-09-01

    We describe a new technology based on thermoforming as a microfabrication process. It significantly enhances the tailoring of polymers for three dimensional tissue engineering purposes since for the first time highly resolved surface and bulk modifications prior to a microstructuring process can be realised. In contrast to typical micro moulding techniques, the melting phase is avoided and thus allows the forming of pre-processed polymer films. The polymer is formed in a thermoelastic state without loss of material coherence. Therefore, previously generated modifications can be preserved. To prove the feasibility of our newly developed technique, so called SMART = Substrate Modification And Replication by Thermoforming, polymer films treated by various polymer modification methods, like UV-based patterned films, and films modified by the bombardment with energetic heavy ions, were post-processed by microthermoforming. The preservation of locally applied specific surface and bulk features was demonstrated e.g. by the selective adhesion of cells to patterned microcavity walls.

  8. Mass spectra of neutral particles released during electrical breakdown of thin polymer films

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1985-01-01

    A special type of time-of-flight mass spectrometer triggered from the breakdown event was developed to study the composition of the neutral particle flux released during the electrical breakdown of polymer films problem. Charge is fed onto a metal-backed polymer surface by a movable smooth platinum contact. A slowly increasing potential from a high-impedance source is applied to the contact until breakdown occurs. The breakdown characteristics is made similar to those produced by an electron beam charging system operating at similar potentials. The apparatus showed that intense instantaneous fluxes of neutral particles are released from the sites of breakdown events. For Teflon FEP films of 50 and 75 microns thickness the material released consists almost entirely of fluorocarbon fragments, some of them having masses greater than 350 atomic mass units amu, while the material released from a 50 micron Kapton film consists mainly of light hydrocarbons with masses at or below 44 amu, with additional carbon monoxide and carbon dioxide. The apparatus is modified to allow electron beam charging of the samples.

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

    PubMed

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

    2016-03-23

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

  10. Properties of solid polymer electrolyte fluorocarbon film. [used in hydrogen/oxygen fuel cells

    NASA Technical Reports Server (NTRS)

    Alston, W. B.

    1973-01-01

    The ionic fluorocarbon film used as the solid polymer electrolyte in hydrogen/oxygen fuel cells was found to exhibit delamination failures. Polarized light microscopy of as-received film showed a lined region at the center of the film thickness. It is shown that these lines were not caused by incomplete saponification but probably resulted from the film extrusion process. The film lines could be removed by an annealing process. Chemical, physical, and tensile tests showed that annealing improved or sustained the water contents, spectral properties, thermo-oxidative stability, and tensile properties of the film. The resistivity of the film was significantly decreased by the annealing process.

  11. Two-dimensional electron beam charging model for polymer films

    NASA Technical Reports Server (NTRS)

    Reeves, R. D.; Balmain, K. G.

    1981-01-01

    A two-dimensional model is developed to describe the charging of strips of thin polymer films above a grounded substrate exposed to a uniform mono-energetic electron beam. The study is motivated by the observed anomalous behavior of geosynchronous satellites, which has been attributed to differential charging of the satellite surfaces exposed to magnetospheric electrons. Surface and bulk electric fields are calcuated at steady state in order to identify regions of high electrical stress, with emphasis on behavior near the material's edge. The model is used to study the effects of some of the experimental parameters, notably beam energy, beam angle of incidence, beam current density, material thickness and material width. Also examined are the consequences of a central gap in the material and a discontinuity in the material thickness.

  12. Photoassisted Holography in Azo Dye Doped Polymer Films.

    PubMed

    Rahmouni, Anouar; Bougdid, Yahya; Moujdi, Sara; Nesterenko, Dmitry V; Sekkat, Zouheir

    2016-11-03

    Holographic storage is one of the most important applications in the field of optics, especially for recording and retrieving data, and information storage by interference patterns in photosensitive materials are no exception in this regard. In this work, we give evidence that holograms recorded by interference of two coherent laser beams in azo dye doped polymer films can be controlled by a third incoherent assisting laser beam. We show that light diffraction can be increased or decreased by an assisting beam depending on the respective orientation of the polarizations of the recording and the assisting beams. We also found that photomanipulation of polarization holograms, prepared by polarization modulation, does not depend on the polarization of the assisting beam, whereas, photomanipulation of holograms prepared by intensity modulation strongly depends on the polarization of the assisting beam. Photoselection is shown to play a major role in the photoassisted diffraction process.

  13. Conductivity of oriented bis-azo polymer films.

    PubMed

    Apitz, Dirk; Bertram, Ralph Peter; Benter, Nils; Sommer-Larsen, Peter; Johansen, Per Michael; Buse, Karsten

    2006-02-13

    The conductivity properties of electro-optic, photoaddressable, dense bis-azo chromophore polymer films are investigated by using samples corona poled at various temperatures. A dielectric spectrometer is applied to measure the frequency dependence of the conductivity at different temperatures before and after heating the material to above the glass transition temperature. The results show that the orientation of the chromophores changes the charge-carrier mobility. Ionic conductivity dominates in a more disordered configuration of the material, while the competing process of hole hopping takes over as a transition to a liquid-crystalline phase occurs when the material is heated to much higher than the glass transition temperature. Such microcrystallization strongly enhances the conductivity.

  14. Bioinspired design and assembly of platelet reinforced polymer films.

    PubMed

    Bonderer, Lorenz J; Studart, André R; Gauckler, Ludwig J

    2008-02-22

    Although strong and stiff human-made composites have long been developed, the microstructure of today's most advanced composites has yet to achieve the order and sophisticated hierarchy of hybrid materials built up by living organisms in nature. Clay-based nanocomposites with layered structure can reach notable stiffness and strength, but these properties are usually not accompanied by the ductility and flaw tolerance found in the structures generated by natural hybrid materials. By using principles found in natural composites, we showed that layered hybrid films combining high tensile strength and ductile behavior can be obtained through the bottom-up colloidal assembly of strong submicrometer-thick ceramic platelets within a ductile polymer matrix.

  15. Influence of temperature on the drainage of thermoresponsive polymer thin film

    NASA Astrophysics Data System (ADS)

    Bussonniere, Adrien; Jackman, Matthew; Leung, Hin Long; Liu, Bo; Liu, Qingxia; Tsai, Peichun Amy

    2016-11-01

    Due to their switchable stability under external excitation, responsive aqueous foams have recently raised interests in various applications, such as washing, cleaning and mineral recovery, where stable foam and controlled destabilization are required. In this work, we investigate the influence of the temperature and polymer concentration on gravitational thin film drainage using a thermoresponsive polymer. The dynamics of film thinning was recorded on the thin film using a thickness measurement method. We successively illuminate the film with three LEDs of different wavelengths. The absolute thickness was accurately deduced using the three interference patterns. The results show an increase of drainage rates with increasing temperature but insignificant influence of polymer concentration (in the range between 50 and 300 mg/L). The thinning process was twice faster above the LCST (lower critical solution temperature) than that at room temperature. Our results of the temperate-dependent drainage show that the thermoresponsive solubility of polymer plays a key role in thin film stability.

  16. 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

  17. Formation of high mass carbon cluster ions from laser ablation of polymers and thin carbon films

    NASA Astrophysics Data System (ADS)

    Creasy, William R.; Brenna, J. T.

    1990-02-01

    Three materials were studied by laser ablation/Fourier transform mass spectrometry, using 266 nm laser radiation: a copolymer of ethylene and tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), and a diamond-like carbon film (DLC). In each case, positive ion mass spectra exhibit primarily even-numbered, high mass carbon clusters (``fullerenes'') of the type previously reported for graphite ablation. In the case of ETFE, a large C+60 peak (``buckminsterfullerene'') was observed. The polymer spectra showed a strong dependence on the number of laser pulses on one spot and the laser power density. For ETFE, the fullerene ion relative intensity first increases and then decreases as a function of the number of laser pulses. For the DLC film, fullerenes are observed with a single laser pulse on a fresh spot of the sample. The results are interpreted in terms of a gas phase growth model for the fullerene ion formation.

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

    SciTech Connect

    Green, Peter F.

    2014-08-15

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

  19. Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes

    SciTech Connect

    Harris, J; Iyer, S; Bernhardt, A; Huh, JY; Hudson, S; Fagan, J; Hobbie, E.

    2011-12-11

    The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assembled as thin conducting coatings on elastic polymer substrates, and the sheet resistance is measured as a function of compression and cyclic strain through impedance spectroscopy. The wrinkling topography, microstructure and transparency of the films are independently characterized using optical microscopy, electron microscopy, and optical absorption spectroscopy. Thin films made from metallic SWCNTs show better durability as flexible transparent conductive coatings, which we attribute to a combination of superior mechanical performance and higher interfacial conductivity.

  20. Preparation of properties of SWNT/graphene oxide type flexible transparent conductive films.

    PubMed

    Kim, Jin Ho; Jung, Jae Mok; Kwak, Jun Young; Jeong, Jung Hyun; Choi, Byung Chun; Lim, Kwon Taek

    2011-08-01

    Single walled carbon nanotube (SWNT)/graphene oxide (GO) hybrid films were prepared by a facile bar coating method on a polyethylene terephthalate substrate using a mixed solution of SWCNTs and GO. An acryl type polymer was employed as a dispersion agent to obtain SWCNT and GO suspension in ethyl alcohol. The SWCNT/GO hybrid films were highly transparent and electrically conductive, showing 80% transmittance and 1.8 x 10(3) ohm/sq surface resistance. The surface resistance of the SWCNT/GO film could be further improved to 750 ohm/sq by hydrazine vapor reduction.

  1. Absorption modulation enhancement of Azo-polymer film induced by plasmonic field

    NASA Astrophysics Data System (ADS)

    Wang, Xiangxian; Zhang, Douguo; Fu, Qiang; Ming, Hai; Wu, Wenxuan; Zhang, Qijin

    2012-11-01

    A thin photochromic film on top of the resist layer can be used as a virtual mask to fabricate super-resolution lithography patterns. In this letter, based on the azobenzene polymer, the absorption intensity of the 365nm LED is effectively modulated by 532nm laser, the modulation degree reaches to 87%.When the silver nanocubes are dropped onto the surface of the polymer film, the modulation degree is significantly higher than that without the nanoparticles in the same intensity of 532nm laser due to the field enhancement of excitation of surface plasmons. The absorption modulation features of the polymer film are favorable for the further smaller line width nanolithography.

  2. Mechanism and Model of Laser-Driven Mass Transport in Thin Films of Azo Polymers

    DTIC Science & Technology

    2007-11-02

    and Model of Laser-Driven Mass Transport in Thin Films of Azo Polymers by C. J. Barrett, A. Natansohn, and P. Rochon Submitted for publication in...DATE June 23, 1998 Tprhnjr.fil P^nnr I’: 4. TITLE AHO SU3TITLE Mechanism and Model of Laser-Driven Mass Transport in Thin Films of Azo Polymers...TRANSPORT IN THIN FILMS OF AZO POLYMERS Christopher J. Barrett’, Almeria L. Natansohn1, and Paul L. Rochon2. ’Dept. of Chemistry. Queen’s

  3. Cellulose nanofibril based graft conjugated polymer films act as a chemosensor for nitroaromatic.

    PubMed

    Niu, Qingyuan; Gao, Kezheng; Wu, Wenhui

    2014-09-22

    A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensor's out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility.

  4. Optoelectronic properties of dicyanofluorene-based n-type polymers.

    PubMed

    Vijayakumar, Chakkooth; Saeki, Akinori; Seki, Shu

    2012-08-01

    Three new donor-acceptor-type copolymers (P1-P3) consisting of dicyanofluorene as acceptor and various donor moieties were designed and synthesized. Optoelectronic properties were studied in detail by means of UV-visible absorption and fluorescence spectroscopy, cyclic voltammetry, space-charge-limited current (SCLC), flash-photolysis time-resolved microwave conductivity (FP-TRMC), and density functional theory (DFT). All polymers showed strong absorption in the UV-visible region and the absorption maximum undergoes redshift with an increasing number of thiophene units in the polymer backbone. SCLC analysis showed that the electron mobilities of the polymers in the bulk state were 1 to 2 orders higher than that of the corresponding hole mobilities, which indicated the n-type nature of the materials. By using FP-TRMC, the intrapolymer charge-carrier mobility was assessed and compared with the interpolymer mobility obtained by SCLC. The polymers exhibited good electron-accepting properties sufficiently high enough to oxidize the excited states of regioregular poly(3-hexylthiophene) (P3HT (donor)), as evident from the FP-TRMC analysis. The P3 polymer exhibited the highest FP-TRMC transients in the pristine form as well as when blended with P3HT. Use of these polymers as n-type materials in all-polymer organic solar cells was also explored in combination with P3HT. In accordance with the TRMC results, P3 exhibited superior electron-transport and photovoltaic properties to the other two polymers, which is explained by the distribution of the energy levels of the polymers by using DFT calculations.

  5. Nanostructured thin film polymer devices for constant-rate protein delivery.

    PubMed

    Bernards, Daniel A; Lance, Kevin D; Ciaccio, Natalie A; Desai, Tejal A

    2012-10-10

    Herein long-term delivery of proteins from biodegradable thin film devices is demonstrated, where a nanostructured polymer membrane controls release. Protein was sealed between two poly(caprolactone) films, which generated the thin film devices. Protein release for 210 days was shown in vitro, and stable activity was established through 70 days with a model protein. These thin film devices present a promising delivery platform for biologic therapeutics, particularly for application in constrained spaces.

  6. Air-stable solution-processed n-channel organic thin film transistors with polymer-enhanced morphology

    SciTech Connect

    He, Zhengran; Shaik, Shoieb; Bi, Sheng; Li, Dawen; Chen, Jihua

    2015-05-04

    N,N′-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN{sub 2}) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN{sub 2} film is much lower than the value of PDIF-CN{sub 2} single crystals made from vapor phase deposition, indicating significant room for mobility enhancement. In this study, various insulating polymers, including poly(vinyl alcohol), poly(methyl methacrylate) (PMMA), and poly(alpha-methylstyrene) (PαMS), are pre-coated on silicon substrate aiming to enhance the morphology of the PDIF-CN{sub 2} thin film, thereby improving the charge transport and air stability. Atomic force microscopy images reveal that with the pre-deposition of PαMS or PMMA polymers, the morphology of the PDIF-CN{sub 2} polycrystalline films is optimized in semiconducting crystal connectivity, domain size, and surface roughness, which leads to significant improvement of organic thin-film transistor (OTFT) performance. Particularly, an electron mobility of up to 0.55 cm{sup 2}/V s has been achieved from OTFTs based on the PDIF-CN{sub 2} film with the pre-deposition of PαMS polymer.

  7. Polymer-metal nanocomposite thin films: In situ fabrication and applications

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, T. P.

    2012-06-01

    Polymer - metal nanocomposites are versatile materials which combine the unique characteristics of the components as well as manifest mutualistic effects. In situ generation of the nanoparticles inside a solid polymer film is a convenient and attractive route to the fabrication of metal nanoparticle - embedded polymer thin films. This presentation will provide an overview of the methodology involved in a simple protocol that we have developed for the fabrication of noble metal nanostructures inside polymer thin films, using aqueous medium for the synthesis and deploying the polymer itself as the reducing as well as stabilizing agent. The in situ growth of metal nanoparticles inside polymer films provides a unique opportunity to generate novel nanomaterials as well as to monitor the growth process in real time. A variety of techniques that have been exploited to characterize the precursor to product transformation inside the polymer film will be reviewed. The control provided by the in situ fabrication route on the size, shape and distribution of the nanostructures, and application of the nanocomposite thin films in a wide range of areas including nonlinear optics, catalysis, sensing and biology, illustrate the versatility of these materials.

  8. Ladderphanes: a new type of duplex polymers.

    PubMed

    Luh, Tien-Yau

    2013-02-19

    A polymeric ladderphane is a step-like structure comprising multiple layers of linkers covalently connected to two or more polymeric backbones. The linkers can be planar aromatic, macrocyclic metal complexes, or three-dimensional organic or organometallic moieties. Structurally, a DNA molecule is a special kind of ladderphane, where the cofacially aligned base-pair pendants are linked through hydrogen bonding. A greater understanding of this class of molecules could help researchers develop new synthetic molecules capable of a similar transfer of chemical information. In this Account, we summarize our studies of the strategy, design, synthesis, characterization, replications, chemical and photophysical properties, and assembly of a range of double-stranded ladderphanes with many fascinating structures. We employed two norbornene moieties fused with N-arylpyrrolidine to connect covalently with a range of relatively rigid linkers. Ring opening metathesis polymerizations (ROMP) of these bis-norbornenes using the first-generation Grubbs ruthenium-benzylidene catalyst produced the corresponding symmetrical double-stranded ladderphanes. The N-arylpyrrolidene moiety in the linker controls the isotactic selectivity and the trans configuration for all double bonds in both single- and double-stranded polynorbornenes. The π-π interactions between these aryl pendants may contribute to the high stereoselectivity in the ROMP of these substrates. We synthesized chiral helical ladderphanes by incorporating asymmetric center(s) in the linkers. Replication protocols and sequential polymerization of a monomer that includes two different polymerizable groups offer methods for producing unsymmetical ladderphanes. These routes furnish template synthesis of daughter polymers with well-controlled chain lengths and polydispersities. The linkers in these ladderphanes are well aligned in the center along the longitudinal axis of the polymer. Fluorescence quenching, excimer formation, or

  9. Polymer dielectric materials for organic thin-film transistors: Interfacial control and development for printable electronics

    NASA Astrophysics Data System (ADS)

    Kim, Choongik

    Organic thin-film transistors (OTFTs) have been extensively studied for organic electronics. In these devices, organic semiconductor-dielectric interface characteristics play a critical role in influencing OTFT operation and performance. This study begins with exploring how the physicochemical characteristics of the polymer gate dielectric affects the thin-film growth mode, microstructure, and OTFT performance parameters of pentacene films deposited on bilayer polymer (top)-SiO2 (bottom) dielectrics. Pentacene growth mode varies considerably with dielectric substrate, and correlations are established between pentacene film deposition temperature, the thin-film to bulk microstructural phase transition, and OTFT device performance. Furthermore, the primary influence of the polymer dielectric layer glass transition temperature on pentacene film microstructure and OTFT response is shown for the first time. Following the first study, the influence of the polymer gate dielectric viscoelastic properties on overlying organic semiconductor film growth, film microstructure, and TFT response are investigated in detail. From the knowledge that nanoscopically-confined thin polymer films exhibit glass transition temperatures that deviate substantially from those of the corresponding bulk materials, pentacene (p-channel) and cyanoperylene (n-channel) films grown on polymer gate dielectrics at temperatures well-below their bulk glass transition temperatures (Tg(b)) have been shown to exhibit morphological/microstructural transitions and dramatic OTFT performance discontinuities at well-defined temperatures (defined as the polymer "surface glass transition temperature," or Tg(s)). These transitions are characteristic of the particular polymer architecture and independent of film thickness or overall film cooperative chain dynamics. Furthermore, by analyzing the pentacene films grown on UV-curable polymer dielectrics with different curing times (hence, different degrees of

  10. Morphological changes of gel-type functional polymers after intermatrix synthesis of polymer stabilized silver nanoparticles.

    PubMed

    Bastos-Arrieta, Julio; Muñoz, Maria; Ruiz, Patricia; Muraviev, Dmitri N

    2013-05-29

    This paper reports the results of intermatrix synthesis (IMS) of silver metal nanoparticles (Ag-MNPs) in Purolite C100E sulfonic ion exchange polymer of the gel-type structure. It has been shown that the surface morphology of the initial MNP-free polymer is absolutely smooth, but it dramatically changes after the kinetic loading of Ag on the polymer and then IMS of Ag-MNPs. These morphological changes can be explained by the interaction of Ag-NPs with the polymer chains, leading to a sort of additional cross-linking of the polymer. As a result, the modification of the gel-type matrix with Ag-MNPs leads to the increase of the matrix cross-linking, which results in the increase of its surface area and the appearance of nanoporosity in the polymer gel. Ag-MNPs are located near the polymer surface and do not form any visible agglomerations. All these features of the nanocomposites obtained are important for their practical applications in catalysis, sensor applications, and bactericide water treatment.

  11. Two-Dimensional Dynamics of Metal Nanoparticles on the Surface of Thin Polymer Films Studied with Coherent X Rays

    SciTech Connect

    Streit, S.; Gutt, C.; Sternemann, H.; Tolan, M.; Chamard, V.; Robert, A.; Sprung, M.

    2007-01-26

    X-ray photon-correlation spectroscopy is used to measure the dynamic structure factor f(q,{tau}) of gold particles moving on the surface of thin polymer films. Above the glass transition of the polymer the peculiar form f(q,{tau}){approx}exp[-({gamma}{tau}){sup {alpha}}] is found with 0.7<{alpha}<1.5, depending on sample age and temperature. The relaxation rates {gamma} scale linearly with q, excluding a simple Brownian diffusive motion. This type of behavior, already observed in aging bulk soft matter systems, is explained by a power law distribution of particle velocities due to ballistic motion.

  12. Promotion of neural cell adhesion by electrochemically generated and functionalized polymer films.

    PubMed

    Blau, A; Weinl, C; Mack, J; Kienle, S; Jung, G; Ziegler, C

    2001-11-15

    New strategies for spatially controllable cell adhesion have been developed for brain cells from embryonic chicken. They are based on electrochemically active phenol and pyrrole derivatives, and can be used for the selective coverage of electroconductive substrates. Besides mimicking standard laminin-related adhesion promoting mechanisms by means of an electroactive monomer-linked 18-peptide segment from laminin (SRARKQAASIKVAVSADR), electrochemically generated thin (6-30 nm) polymer films of 3-hydroxybenzyl-hydrazine (3HBH) and 2-(3-hydroxyphenyl)-ethanol (2(3HP)E) with and without mechanically entrapped or covalently linked D-lysine have proved to promote cell adhesion in serum-free medium on indium-doped tin oxide (ITO) substrates during the first 6 culturing days in vitro. The effectiveness of the peptide was strongly density-dependent. Unexpectedly, laminin itself or a combination of laminin and poly-D-lysine (PDL) did not promote cell adhesion and neuron differentiation in serum-free cultures on ITO. However, they worked perfectly well on regular polystyrene substrates in serum-free medium or on ITO when medium with serum was used. This finding might suggest that the adhesion efficiency of laminin does not depend only on the kind of medium supplement but also on the type of substrate. In contrast, the adhesion-promoting properties of "artificial" polymeric films seemed to be based on a more direct cell-film interaction, with the film masking the substrate properties.

  13. Measuring the Thickness and Elastic Properties of Electroactive Thin-film Polymers Using Platewave Dispersion Data

    NASA Technical Reports Server (NTRS)

    El-Azab, A.; Mal, A. K.; Bar-Cohen, Y.; Lih, S.

    1996-01-01

    Electroactive thin-film polymers are candidate sensors and actuators materials [1,2]. They are also finding a significant potential for applications in muscle mechanisms and micro-electro-mechanical systems (MEMS).

  14. Characteristics and Mechanisms in Ion-Conducting Polymer Films as Chemical Sensors

    SciTech Connect

    HUGHES,ROBERT C.; YELTON,WILLIAM G.; PFEIFER,KENT B.; PATEL,SANJAY V.

    2000-07-12

    Solid Polymer Electrolytes (SPE) are widely used in batteries and fuel cells because of the high ionic conductivity that can be achieved at room temperature. The ions are usually Li or protons, although other ions can be shown to conduct in these polymer films. There has been very little published work on SPE films used as chemical sensors. The authors have found that thin films of polymers like polyethylene oxide (PEO) are very sensitive to low concentrations of volatile organic compounds (VOCs) such as common solvents. Evidence of a new sensing mechanism involving the percolation of ions through narrow channels of amorphous polymer is presented. They present impedance spectroscopy of PEO films in the frequency range 0.0001 Hz to 1 MHz for different concentrations of VOCs and relative humidity. They find that the measurement frequency is important for distinguishing ionic conductivity from the double layer capacitance and the parasitic capacitance.

  15. Anchoring Strength of Thin Aligned-Polymer Films Formed by Liquid Crystalline Monomer

    NASA Astrophysics Data System (ADS)

    Murashige, Takeshi; Fujikake, Hideo; Ikehata, Seiichiro; Sato, Fumio

    2003-04-01

    We have evaluated the polar anchoring strength of a thin molecule-aligned polymer film formed by a liquid crystalline monomer. The polymer film was obtained by photopolymerization of the monomer oriented by a rubbed polyimide alignment layer in a chamber filled with N2 gas. We fabricated a nematic liquid crystal cell using the thin aligned-polymer films as alignment layers, and then evaluated the anchoring strength of the polymer by measuring the optical retardation curve of the cell driven by voltages. The experimental result showed that the anchoring strength was one order of magnitude lower than that of a conventional rubbed polyimide alignment layer, and decreased with increasing the cure temperature of the monomer film.

  16. Thin polymer film collectors as a contribution to the solar industry

    SciTech Connect

    Wilhelm, W.G.

    1984-06-01

    Achievements made in research on thin polymer film solar flat-plate collectors using monocoque construction techniques are briefly discussed. The significance of these achievements for cost reduction of flat-plate collectors without compromising performance is briefly discussed.

  17. Preparation and characterization of lanthanide-azo-dye coordination polymers and polymer thin films via layer-by-layer depositions.

    PubMed

    Han, Li-Wei; Lü, Jian; Liu, Tian-Fu; Gao, Shui-Ying; Cao, Rong

    2010-12-07

    A series of tartrazine-lanthanide dye compounds has been synthesized and characterized. Structural studies reveal that the light rare-earth elements La, Ce, Pr and Nd form coordination compounds with tartrazine ligands in a 1:1 ratio and result in 1-D 'fish-bone' chain-like structures having uncoordinated organosulfonate groups on each side of the chain. However, reactions of tartrazine and heavy rare-earth elements Ho, Er, Tm and Yb, in the presence of auxiliary 1,10-phenanthroline, give new 1-D coordination polymers in which uncoordinated organosulfonate groups are located on the same side of the chains. The tartrazine ligands display similar but slightly different coordination modes in both types of structures and the 1,10-phenanthroline plays a vital role in the formation of heavy rare-earth dye compounds. Based on the knowledge of their structures, the light rare-earth dye compounds were utilized to assemble with positively-charged PEI into multilayer thin films by means of layer-by-layer depositions. The as-synthesized thin films showed enhanced stability and consistency on solid surfaces.

  18. Facility and Methods Developed for Simulated Space Vacuum Ultraviolet Exposure Testing of Polymer Films

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

    2002-01-01

    Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the Sun in the space environment can degrade polymer films, producing changes in their optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultralightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. The NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of combined or sequential simulated space environmental exposures to determine combined damaging effects with other aspects of the space environment, which include solar ultraviolet radiation, solar flare x-rays, electron and proton radiation, atomic oxygen (for low-Earth-orbit missions), and temperature effects. Because the wavelength sensitivity of VUV damage is not well known for most materials, Glenn's VUV facility uses a broad-spectrum deuterium lamp with a magnesium fluoride window that provides output between 115 and 200 nm. Deuterium lamps of this type were characterized by the National Institute of Standards and Technology and through measurements at Glenn. Spectral irradiance measurements show that from approximately 115 to 160 nm, deuterium lamp irradiance can be many times that of air mass zero solar irradiance, and as wavelength increases above approximately 160 nm, deuterium lamp irradiance decreases in comparison to the Sun. The facility is a cryopumped vacuum chamber that achieves a system pressure of approximately 5310(exp -6) torr. It contains four individual VUV-exposure compartments in vacuum, separated by water-cooled copper walls to minimize VUV radiation and any sample contamination cross interactions between compartments. Each VUV-exposure compartment contains a VUV deuterium lamp, a motor-controlled sample stage coupled with a

  19. Molecular depth profiling of multilayer polymer films using time-of-flight secondary ion mass spectrometry.

    PubMed

    Wagner, M S

    2005-02-01

    The low penetration depth and high sputter rates obtained using polyatomic primary ions have facilitated their use for the molecular depth profiling of some spin-cast polymer films by secondary ion mass spectrometry (SIMS). In this study, dual-beam time-of-flight (TOF) SIMS (sputter ion, 5 keV SF(5)(+); analysis ion, 10 keV Ar(+)) was used to depth profile spin-cast multilayers of poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate) (PHEMA), and trifluoroacetic anhydride-derivatized poly(2-hydroxyethyl methacrylate) (TFAA-PHEMA) on silicon substrates. Characteristic positive and negative secondary ions were monitored as a function of depth using SF(5)(+) primary ion doses necessary to sputter through the polymer layer and uncover the silicon substrate (>5 x10(14) ions/cm(2)). The sputter rates of the polymers in the multilayers were typically less than for corresponding single-layer films, and the order of the polymers in the multilayer affected the sputter rates of the polymers. Multilayer samples with PHEMA as the outermost layer resulted in lowered sputter rates for the underlying polymer layer due to increased ion-induced damage accumulation rates in PHEMA. Additionally, the presence of a PMMA or PHEMA overlayer significantly decreased the sputter rate of TFAA-PHEMA underlayers due to ion-induced damage accumulation in the overlayer. Typical interface widths between adjacent polymer layers were 10-15 nm for bilayer films and increased with depth to approximately 35 nm for the trilayer films. The increase in interface width and observations using optical microscopy showed the formation of sputter-induced surface roughness during the depth profiles of the trilayer polymer films. This study shows that polyatomic primary ions can be used for the molecular depth profiling of some multilayer polymer films and presents new opportunities for the analysis of thin organic films using TOF-SIMS.

  20. Auger analysis of films formed on metals in sliding contact with halogenated polymers

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The use of Auger electron spectroscopy (AES) to search for transferred polymer must contend with the fact that there has been no published work on Auger analysis of polymers. Since this is a new area for AES, the Auger spectra of polymers and of halogenated polymers in particular is discussed. It is shown that the Auger spectra of halogenated polymers have certain characteristics that permit an assessment of whether a polymeric transfer film has been established by sliding contact. The discussion is general and the concepts should be useful in considering the Auger analysis of any polymer. The polymers chosen for this study are the halogenated polymers polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polychlorotrifluorethylene (PCTFE).

  1. Polymer Nanocomposite Films: Dispersion of Polymer Grafted Nanorods and Optical Properties

    NASA Astrophysics Data System (ADS)

    Composto, Russell

    2013-03-01

    The thermodynamic factors that affect the dispersion of polymer-brush grafted gold nanorods (NR) in polymer matrix films have been studied by experiment and theory. When brush and matrix have a favorable interaction, such as poly(ethylene oxide) (PEO)-NR/ poly(methyl methacrylate) (PMMA) and polystyrene (PS)-NR / poly(2,6-dimethyl-p-phenylene oxide) (PPO), nanorods are uniformly dispersed. For PEO-NRs in PMMA, the NRs are regularly spaced and well dispersed, independent of the ratio of the degree of polymerization of the matrix (P) to that of the brush (N), namely P/N. As the NR volume fraction increases, the local orientation of the nanorods increases, whereas the macroscopic orientation remains isotropic. When the brush and matrix are similar (i.e., PS-NR / PS and PEO-NR / PEO), the nanorods randomly disperse for P/N < 2 (i.e., wet brush), but align side-by-side in aggregates for P/N > 2. UV-visible spectroscopy and discrete dipole approximation (DDA) calculations demonstrate that surface plasmon coupling leads to a blue shift in the longitudinal surface plasmon resonance (LSPR) as P/N increases. For P/N > 2, self-consistent field theory (SCFT) calculations and Monte Carlo (MC) simulations indicate that nanorod aggregation is caused by depletion-attraction forces. Starting with a dry brush system, namely, a PS matrix where P/N = 30, these attractive forces can be mediated by adding a compatibilizing agent (e.g., PPO) that drives the NRs to disperse. Finally, dry and wet brush behavior is observed for NR aspect ratios varying from 2.5 to 7. However, compared at the same volume fraction, long rods for the dry case exhibit much better local order than lower aspect ratio nanorods, suggesting that long rods may exhibit nematic-like ordering at higher loadings. NSF Polymer and CEMRI Programs.

  2. Measurement of desorbed products during organic polymer thin film etching by plasma beam irradiation

    SciTech Connect

    Kurihara, Kazuaki; Karahashi, Kazuhiro; Egami, Akihiro; Nakamura, Moritaka

    2006-11-15

    The authors investigated the etching characteristics of three kinds of methacrylate polymer films, which have the same main chain but with different side chains, using a plasma beam irradiation apparatus. The polymers are polytbutylmethacrylate, polybenzylmethacrylate, and polycyclohexylmethacrylate. The major desorbed products during nitrogen plasma beam etching were found to be HCN and C{sub 2}N{sub 2} for all methacrylate polymer films. The desorbed products originating from the polymer structure, namely, the main chain and the side chain, were hardly observed. The energy distributions of desorbed products were mainly composed of Maxwell-Boltzmann distribution with a small component of collision cascade distribution for all three polymers and were slightly dependent on the ion energy. It is concluded that chemical sputtering, which can be defined as the production of weakly bound species by ion bombardment, followed by thermal desorption, is the significant ion induced mechanism of organic polymer etching.

  3. Gold-on-Polymer-Based Sensing Films for Detection of Organic and Inorganic Analytes in the Air

    NASA Technical Reports Server (NTRS)

    Manatt, Kenneth; Homer, Margie; Ryan, Margaret; Kisor, Adam; Shevade, Abhijit; Jewell, April; Zhou, Hanying

    2008-01-01

    A document discusses gold-on-polymer as one of the novel sensor types developed for part of the sensor development task. Standard polymer-carbon composite sensors used in the JPL Electronic Nose (ENose) have been modified by evaporating 15 nm of metallic gold on the surface. These sensors have been shown to respond to alcohols, aromatics, ammonia, sulfur dioxide, and elemental mercury in the parts-per-million and parts-per-billion concentration ranges in humidified air. The results have shown good sensitivity of these films operating under mild conditions (operating temperatures 23-28 C and regeneration temperature up to 40 C). This unique sensor combines the diversity of polymer sensors for chemical sensing with their response to a wide variety of analytes with the specificity of a gold sensor that shows strong reaction/binding with selected analyte types, such as mercury or sulfur.

  4. Alignment mechanism of liquid crystal in a stretched porous polymer film

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Kuboki, Masashi; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-09-01

    This article discusses the mechanism of nematic liquid crystal alignment in stretched porous polymer films. The polymer films were formed by extreme stretching of an isotropic porous polyolefin, such that the draw ratio was 12:1. A 6-μm-thick porous film with a high porosity coefficient of 92% revealed fine string-shaped areas that exhibited optical anisotropy due to their possessing a high degree of molecular alignment. The porous film was filled with nematic liquid crystal and then the composite film was sandwiched between transparent electrodes coated onto glass substrates, without the use of conventional alignment layers. From polarizing microscopy observations it was found that the string-like polymer areas induce liquid crystal molecular alignment. The liquid crystal cells can exhibit an electrically controlled birefringence effect. This alignment technique enables us to realize three-dimensional control of liquid crystal alignment.

  5. A multifunctional polymer-graphene thin-film transistor with tunable transport regimes.

    PubMed

    Mosciatti, Thomas; Haar, Sébastien; Liscio, Fabiola; Ciesielski, Artur; Orgiu, Emanuele; Samorì, Paolo

    2015-03-24

    Here we describe a strategy to fabricate multifunctional graphene-polymer hybrid thin-film transistors (PG-TFT) whose transport properties are tunable by varying the deposition conditions of liquid-phase exfoliated graphene (LPE-G) dispersions onto a dielectric surface and via thermal annealing post-treatments. In particular, the ionization energy (IE) of the LPE-G drop-cast on SiO2 can be finely adjusted prior to polymer deposition via thermal annealing in air environment, exhibiting values gradually changing from 4.8 eV up to 5.7 eV. Such a tunable graphene's IE determines dramatically different electronic interactions between the LPE-G and the semiconducting polymer (p- or n-type) sitting on its top, leading to devices where the output current of the PG-TFT can be operated from being completely turned off up to modulable. In fact upon increasing the surface coverage of graphene nanoflakes on the SiO2 the charge transport properties within the top polymer layer are modified from being semiconducting up to truly conductive (graphite-like). Significantly, when the IE of LPE-G is outside the polymer band gap, the PG-TFT can operate as a multifunctional three terminal switch (transistor) and/or memory device featuring high number of erase-write cycles. Our PG-TFT, based on a fine energy level engineering, represents a memory device operating without the need of a dielectric layer separating a floating gate from the active channel.

  6. Modeling the mechanics of graphene-based polymer composite film measured by the bulge test

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Jun; Sun, You-yi; Li, Dian-sen; Cao, Yang; Wang, Zuo; Ma, Jing; Zhao, Gui-Zhe

    2015-10-01

    Graphene-based polymer composite films have wide-ranging potential applications, such as in sensors, electromagnetic shielding, absorbing materials, corrosion resistance and so on. In addition, the practical applications of graphene-based polymer composite films are closely related to their mechanical properties. However, the mechanical properties of graphene-based polymer composite films are difficult to characterize with tensile tests. In this paper, the bugle test was used to investigate the mechanical properties of graphene-based polymer composite films. The experimental results show that the Young’s modulus of polymer composite films increases non-linearly with an increase in the doping content of graphene, and viscoelastic deformation is induced under cyclic loading conditions. Moreover, in order to describe their mechanical behavior, an ‘Arruda-Boyce’ finite-strain constitutive model (modified BPA model), based on the strain amplification hypothesis, and a traditional ‘Arruda-Boyce’ model was proposed, which incorporated many of the features of previous theories. The numerical treatment of the modified BPA model associated with finite element analysis is also discussed. This new model is shown to be able to predict the experimentally observed mechanical behavior of graphene based polymer composite films measured by the bugle test effectively.

  7. Chain conformation near the substrate interface in nanoparticle stabilized polymer thin films

    NASA Astrophysics Data System (ADS)

    Barkley, Deborah; Sen, Mani; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori; Yuan, Guangcui; Satija, Sushil; Zhang, Yugang; Gang, Oleg; Karim, Alamgir

    When nanoparticles (NPs) are added to polymer thin films, they often migrate to the film-substrate interface and form a ``diffused immobile interfacial layer'', which serves to screen the polymer-substrate interaction and suppress dewetting. The fundamental, but unsolved question is how the conformations of the polymer chains in the layer are affected by the NPs and how that impacts the enhancement of film stability. To address the question, we used dodecane thiol-functionalized gold NPs (2.4 nm diameter) and polystyrene (PS, Mw =30kDa). We found that the critical concentration of the Au NPs to induce complete dewetting suppression of 20 nm-thick PS/Au thin films on cleaned Si substrates is 5 wt% (wt of particle/wt of polymer). To investigate the interfacial structures at the polymer-solid interface, we rinsed the annealed PS/Au thin films with toluene and characterized the residual interfacial layers by using various x-ray and neutron scattering techniques. The results indicate that the conformation of the polymer chains closer to the substrate becomes less flattened with the addition of gold NPs, allowing chains at the substrate to entangle more effectively with free chains comprising the bulk film. The detailed mechanism will be discussed. T.K. acknowledges funding from NSF Grant (CMMI-1332499).

  8. Polymer-grafted gold nanorods in polymer thin films: Dispersion and plasmonic coupling

    NASA Astrophysics Data System (ADS)

    Hore, Michael-Jon Ainsley

    This dissertation describes complementary experimental and theoretical studies to deter- mine the thermodynamic factors that affect the dispersion of polymer-grafted Au nanorods within polymer thin films. Au nanorods exhibit a uniform dispersion with a regular spacing for favorable brush / matrix interactions, such as poly(ethylene glycol) (PEG)-Au / poly(methyl methacrylate) (PMMA) and polystyrene (PS)-Au / poly(2,6-dimethyl-p-phenylene oxide) (PPO). For PEG-Au / PMMA, the nanorods are locally oriented and their dispersion is independent of the ratio of the degree of polymerization of the matrix (P) to that of the brush (N), α = P/N, whereas for chemically similar brush / matrix combinations, such as PS-Au / PS and PEG-Au / poly(ethylene oxide) (PEO), nanorods are randomly dispersed for α 2. For aggregated systems (α > 2), nanorods are found primarily within aggregates containing side-by-side aligned nanorods with a spacing that scales with N. UV-visible spectroscopy and discrete dipole approximation (DDA) calculations demonstrate that coupling between surface plasmons within the aggregates leads to a blue shift in the optical absorption as α increases, indicating the sensitivity of spectroscopy for determining nanorod dispersion in polymer nanocomposite films. Self-consistent field theory (SCFT) calculations and Monte Carlo (MC) simulations show that the aggregation of nanorods for α > 2 can be attributed to depletion-attraction forces caused by autophobic dewetting of the brush and matrix. Finally, miscible blends of PS and PPO are investigated as a route to control depletion-attraction interactions between PS-Au nanorods. Initially, nanorods aggregate in matrices having 50 vol. % PPO and then gradually disperse as PPO becomes the majority component. The brush and matrix density profiles, determined by SCFT, show that PPO segregates into the PS brush, and acts as a compatibilizer, which improves dispersion. As dispersion improves, coupling between surface

  9. A novel mucoadhesive polymer film composed of carbopol, poloxamer and hydroxypropylmethylcellulose.

    PubMed

    Kim, Tae Hee; Ahn, Jae Soon; Choi, Hoo Kyun; Choi, Yun Jaie; Cho, Chong Su

    2007-03-01

    Using the casting method novel mucoadhesive polymer blend film consisting of Carbopol, poloxamer, and hydroxypropylmethylcellulose (HPMC) was prepared and characterized. Triamcinolone acetonide (TAA) was loaded into Carbopol/poloxamer/HPMC polymer blend film. Carbonyl band of Carbopol in Carbopol/poloxamer/HPMC shifted to longer wavenumber than that of Carbopol in Carbopol/poloxamer due to the hydrogen bonding among Carbopol, poloxamer, and HPMC. Tan delta peak assigned to glass transition temperature (Tg) of HPMC shifted to low temperature due to increased flexibility caused by increased poloxamer content in polymer blend films. Swelling ratio of Carbopol/poloxamer/HPMC films was lowest in Carbopoll poloxamer/HPMC at mixing ratio of 35/30/35 (wt/wt/wt). Adhesive force of Carbopol/poloxamer/HPMC films increased with increasing HPMC content in Carbopol/poloxamer/HPMC polymer blend film and increasing hydroxypropyl group content in HPMC due to hydrophobic property of HPMC although bioadhesive force was highest at mixing ratio of 35/30/35 (wt/wt/ wt). Release of TAA from TAA-loaded Carbopol/poloxamer/HPMC polymer blend film in vitro increased with increasing loading content of drug.

  10. Layer-by-layer assembly of clay-filled polymer nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Jang, Woo-Sik

    2008-10-01

    A variety of functional thin films can be produced using the layer-by-layer assembly technique. In this work, assemblies of anionic clay and cationic polymer were studied with regard to film growth and gas barrier properties. A simple, yet flexible robotic dipping system, for the preparation of these thin films, was built. The robot alternately dips a substrate into aqueous mixtures with rinsing and drying in between. Thin films of sodium montmorillonite clay and cationic polymer were grown and studied on poly(ethylene terephthalate) film or a silicon wafer. After 30 clay polymer bilayers were deposited, the resulting transparent film had an oxygen transmission rate (OTR) below 0.005 cm3/m2/day/atm. This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a "brick wall" nanostructure comprised of completely exfoliated clay bricks in polymeric "mortar". The growth of polymer and clay assemblies is then shown to be controlled by altering the pH of polyethylenimine (PEI). Growth, oxygen permeability, and mechanical behavior of clay-PEI assemblies were studied as a function of pH in an effort to tailor the behavior of these thin films. Thicker deposition at high pH resulted in reduced oxygen permeability and lower modulus, which highlights the tailorability of this system.

  11. Room-temperature preparation of trisilver-copper-sulfide/polymer based heterojunction thin film for solar cell application

    NASA Astrophysics Data System (ADS)

    Lei, Yan; Yang, Xiaogang; Gu, Longyan; Jia, Huimin; Ge, Suxiang; Xiao, Pin; Fan, Xiaoli; Zheng, Zhi

    2015-04-01

    Solar cells devices based on inorganic/polymer heterojunction can be a possible solution to harvest solar energy and convert to electric energy with high efficiency through a cost-effective fabrication. The solution-process method can be easily used to produce large area devices. Moreover, due to the intrinsic different charge separation, diffusion or recombination in various semiconductors, the interfaces between each component may strongly influence the inorganic/polymer heterojunction performance. Here we prepared a n-type Ag3CuS2 (Eg = 1.25 eV) nanostructured film through a room-temperature element reaction process, which was confirmed as direct bandgap semiconductor through density function theory simulation. This Ag3CuS2 film was spin-coated with an organic semiconducting poly(3-hexythiophene) (P3HT) or polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) film, which formed an inorganic/polymer heterojunction. After constructing it to a solar cell device, the power conversion efficiencies of 0.79% and 0.31% were achieved with simulated solar illumination on Ag3CuS2/P3HT and Ag3CuS2/PTB7, respectively. A possible mechanism was discussed and we showed the charge separation at interface of inorganic and polymer semiconductors played an important role.

  12. High-mobility and air-stable organic thin-film transistors with highly ordered semiconducting polymer films

    NASA Astrophysics Data System (ADS)

    Umeda, Tokiyoshi; Tokito, Shizuo; Kumaki, Daisuke

    2007-03-01

    We report on high crystalline thin films of liquid-crystalline polythiophene derivative, poly(2,5-bis(3-hexadecylthiophene-2-yl)thieno[3,2-b]thiophene) (PB16TTT) that exhibit terrace structures and molecular steps of its polymer chains by annealing in its liquid-crystalline phase. The crystallinity of the PB16TTT polymer films formed on SiO2 gate insulating layers with smooth self-assembled monolayer was improved by changing the octyltrichlorosilane treatment time for the SiO2, which led to reproducible high field-effect mobilities of the polymer thin-film transistors up to 0.44cm2/Vs. High stability of the transistor for repeated stressing in ambient air was also demonstrated.

  13. Stress Induced Mechano-electrical Writing-Reading of Polymer Film Powered by Contact Electrification Mechanism

    NASA Astrophysics Data System (ADS)

    Goswami, Sumita; Nandy, Suman; Calmeiro, Tomás R.; Igreja, Rui; Martins, Rodrigo; Fortunato, Elvira

    2016-01-01

    Mechano-electrical writing and reading in polyaniline (PANI) thin film are demonstrated via metal-polymer contact electrification mechanism (CEM). An innovative conception for a non-destructive self-powered writable-readable data sheet is presented which can pave the way towards new type of stress induced current harvesting devices. A localized forced deformation of the interface has been enacted by pressing the atomic force microscopic probe against the polymer surface, allowing charge transfer between materials interfaces. The process yields a well-defined charge pattern by transmuting mechanical stress in to readable information. The average of output current increment has been influenced from 0.5 nA to 15 nA for the applied force of 2 nN to 14 nN instead of electrical bias. These results underscore the importance of stress-induced current harvesting mechanism and could be scaled up for charge patterning of polymer surface to writable-readable data sheet. Time evolutional current distribution (TECD) study of the stress-induced patterned PANI surface shows the response of readability of the recorded data with time.

  14. Stress Induced Mechano-electrical Writing-Reading of Polymer Film Powered by Contact Electrification Mechanism

    PubMed Central

    Goswami, Sumita; Nandy, Suman; Calmeiro, Tomás R.; Igreja, Rui; Martins, Rodrigo; Fortunato, Elvira

    2016-01-01

    Mechano-electrical writing and reading in polyaniline (PANI) thin film are demonstrated via metal-polymer contact electrification mechanism (CEM). An innovative conception for a non-destructive self-powered writable-readable data sheet is presented which can pave the way towards new type of stress induced current harvesting devices. A localized forced deformation of the interface has been enacted by pressing the atomic force microscopic probe against the polymer surface, allowing charge transfer between materials interfaces. The process yields a well-defined charge pattern by transmuting mechanical stress in to readable information. The average of output current increment has been influenced from 0.5 nA to 15 nA for the applied force of 2 nN to 14 nN instead of electrical bias. These results underscore the importance of stress-induced current harvesting mechanism and could be scaled up for charge patterning of polymer surface to writable-readable data sheet. Time evolutional current distribution (TECD) study of the stress-induced patterned PANI surface shows the response of readability of the recorded data with time. PMID:26786701

  15. Equilibrium and Dynamical Behavior of Slip in Polymer Films

    NASA Astrophysics Data System (ADS)

    Priezjev, Nikolai; Troian, Sandra

    2003-11-01

    Slip behavior in small fluidic devices can strongly modify predictions of the flow rates. In an effort to understand the fundamental basis for slip, we have conducted MD simulations of liquid films modeled as N-mer polymer chains (1≤N≤16) in steady Couette flow. The results are consistent with a slip length response of the form L_s=L^os lF(dotγ), where L^os denotes the asymptotic value of the slip length as dotγarrow 0 and lF(dotγ) is a function describing the dynamic response. We discuss the dependence of the slip length on molecular weight and show that the results for L^os agree extremely well with predictions based on a Green-Kubo analysis of the friction imposed by the wall on the first fluid layer [1]. The dynamic response lF(dotγ) is well represented by (1-dotγ/dotγ_c)-0.50 ± 0.05 even for the longest chains [2]. These findings offer an encouraging start for understanding which mechanisms contribute to large slip lengths. [1] J.L. Barrat and L. Bocquet, Phys. Rev. Lett. 82, 4671 (1999) [2] P. A. Thompson and S. M. Troian, Nature, 389, 360 (1997).

  16. Stretchability of freestanding and polymer-supported serpentine thin films

    NASA Astrophysics Data System (ADS)

    Lu, Nanshu; Yang, Shixuan

    2015-03-01

    High-performance stretchable electronics integrate high-quality inorganic electronic materials such as metal, semiconductor and oxide with deformable polymer substrates. To minimize strains in inorganic materials under large deformation, metal and ceramic thin films can both be patterned into meandering serpentine ribbons which can rotate and twist to accommodate the applied strain. We have systematically investigated the effects of geometry and substrate stiffness on the stretchability of serpentines through both theoretically and experimental means. For freestanding serpentines, closed-form analytical results are obtained and validated by experiments. To investigate the effect of substrates, indium tin oxide (ITO) serpentines are patterned on both polyimide and elastomeric substrates with systematically changing geometries. While stiff substrates such as polyimide almost completely prevents the rotation or twist of the serpentines, soft substrates can provide serpentines with reasonable freedom of rotation and twisting, which yields stretchability of ITO ribbons beyond 100%. But new failure mechanisms have been found on soft substrates. This work is supported by the NSF NERC - NASCENT under Grant No. 1160494.

  17. Water Soluble Polymer Films for Intravascular Drug Delivery of Antithrombotic Biomolecules

    PubMed Central

    Scott, Rebecca A.; Park, Kinam; Panitch, Alyssa

    2012-01-01

    Over the past 10 years, the number of percutaneous coronary intervention (PCI) procedures performed in the United States has increased by 33%; however, restenosis, which inhibits complete functional recovery of the vessel wall, remains a complication of this procedure. To traverse the complications associated with PCI, the investigation of therapeutic delivery has become an integral topic in modern research. One such therapeutic, a mimic of the proteoglycan decorin, termed DS-SILY, can mask exposed collagen and thereby effectively decrease platelet activation, has recently been developed by our lab. Drawing inspiration from coating technologies developed by the pharmaceutical industry, a fast-dissolving polymer film has been developed to deliver active therapeutic agents from a balloon catheter during PCI. This research investigates the release of DS-SILY from fast-dissolving polymer films composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG). Thin, uniform polymer films were produced via spin coating technique. The dissolution speed of the polymer films was found to be dependent on the concentration of polymer solution, where at least 65% of the films were shown to dissolve into nanometer sized polymer fragments within two minutes. DS-SILY, up to 6.26 μg/cm2, was loaded into the films and functional release of the mimic was demonstrated by its successful binding to collagen upon release. Furthermore, DS-SILY released from films resulted in increased platelet inhibition. These results indicate that use of fast-dissolving polymer films allow for the successful release of biomolecules and further investigation of their use for localized drug delivery during PCI procedures is warranted. PMID:23262161

  18. Water soluble polymer films for intravascular drug delivery of antithrombotic biomolecules.

    PubMed

    Scott, Rebecca A; Park, Kinam; Panitch, Alyssa

    2013-05-01

    Over the past 10 years, the number of percutaneous coronary intervention (PCI) procedures performed in the United States has increased by 33%; however, restenosis, which inhibits complete functional recovery of the vessel wall, remains a complication of this procedure. To traverse the complications associated with PCI, the investigation of therapeutic delivery has become an integral topic in modern research. One such therapeutic, a mimic of the proteoglycan decorin, termed DS-SILY, can mask exposed collagen and thereby effectively decrease platelet activation, has recently been developed by our lab. Drawing inspiration from coating technologies developed by the pharmaceutical industry, a fast-dissolving polymer film has been developed to deliver active therapeutic agents from a balloon catheter during PCI. This research investigates the release of DS-SILY from fast-dissolving polymer films composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG). Thin, uniform polymer films were produced via spin coating technique. The dissolution speed of the polymer films was found to be dependent on the concentration of polymer solution, where at least 65% of the films were shown to dissolve into nanometer sized polymer fragments within 2 min. DS-SILY, up to 6.26 μg/cm(2), was loaded into the films and functional release of the mimic was demonstrated by its successful binding to collagen upon release. Furthermore, DS-SILY released from films resulted in increased platelet inhibition. These results indicate that use of fast-dissolving polymer films allow for the successful release of biomolecules and further investigation of their use for localized drug delivery during PCI procedures is warranted.

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

    PubMed

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

    2016-06-28

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

  20. 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.

  1. Characteristics and cytocompatibility of biodegradable polymer film on magnesium by spin coating.

    PubMed

    Xu, Liping; Yamamoto, Akiko

    2012-05-01

    In recent years, magnesium and its alloys have been investigated as biodegradable metallic materials in cardiovascular stents and bone implants. However, rapid corrosion rate in the early stage of the degradation process greatly influences the cytocompatibility and hinters their application. In this research, biodegradable polymer films are prepared under same coating condition by spin coating in order to improve the early corrosion resistance and cytocompatibility of Mg. The results present that uniform, nonporous, amorphous PLLA and semi-crystalline PCL films are coated on Mg. PLLA film shows better adhesion strength to Mg substrate than that of PCL film. For both PLLA and PCL, low molecular weight (LMW) film is thinner and exhibits better adhesion strength than high molecular weight (HMW) one. SaOS-2 cells show significantly good attachment and high growth on the polymer-coated Mg, demonstrating that all the polymer films can significantly improve the cytocompatibility in the 7-day incubation. The pH measurement of the immersion medium and the quantification of released Mg(2+) during the cell culture clearly indicate that the corrosion resistance of Mg substrate is improved by the polymer films to different extents. It can be concluded that both PLLA and PCL films are promising protective coatings for improving the initial corrosion resistance and cytocompatibility.

  2. Low temperature deposition of polycrystalline silicon thin films on a flexible polymer substrate by hot wire chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Sang-hoon; Jung, Jae-soo; Lee, Sung-soo; Lee, Sung-bo; Hwang, Nong-moon

    2016-11-01

    For the applications such as flexible displays and solar cells, the direct deposition of crystalline silicon films on a flexible polymer substrate has been a great issue. Here, we investigated the direct deposition of polycrystalline silicon films on a polyimide film at the substrate temperature of 200 °C. The low temperature deposition of crystalline silicon on a flexible substrate has been successfully made based on two ideas. One is that the Si-Cl-H system has a retrograde solubility of silicon in the gas phase near the substrate temperature. The other is the new concept of non-classical crystallization, where films grow by the building block of nanoparticles formed in the gas phase during hot-wire chemical vapor deposition (HWCVD). The total amount of precipitation of silicon nanoparticles decreased with increasing HCl concentration. By adding HCl, the amount and the size of silicon nanoparticles were reduced remarkably, which is related with the low temperature deposition of silicon films of highly crystalline fraction with a very thin amorphous incubation layer. The dark conductivity of the intrinsic film prepared at the flow rate ratio of RHCl=[HCl]/[SiH4]=3.61 was 1.84×10-6 Scm-1 at room temperature. The Hall mobility of the n-type silicon film prepared at RHCl=3.61 was 5.72 cm2 V-1s-1. These electrical properties of silicon films are high enough and could be used in flexible electric devices.

  3. Growth and characterization of CdS thin films on polymer substrates for photovoltaic applications.

    PubMed

    Park, Yongseob; Kim, Eung Kwon; Lee, Suho; Lee, Jaehyeong

    2014-05-01

    In this work, cadmium sulfide (CdS) films were deposited on flexible polymer substrates such as polycarbonate (PC) and polyethylene terephthalate (PET). The r.f. magnetron sputtering, which is cost-effective scalable technique, was used for the film deposition. The structural and optical properties of the films grown at different sputtering pressures were investigated. When the CdS film was deposited at lower pressure, the crystallinity and the preferred orientation toward c-axis in hexagonal phase was improved. However, the optical transmittance was reduced as the sputtering pressure was decreased. Compared with the glass substrate, CdS films grown on polymer substrates were exhibited some wore structural and optical characteristics. CdTe thin film solar cell applied to sputtered CdS as a window layer showed a maximum efficiency of 11.6%.

  4. Durability of ITO-MgF2 Films for Space-Inflatable Polymer Structures

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.; Waters, Deborah L.; Schieman, David A.; Hambourger, Paul D.

    2003-01-01

    This paper presents results from ITO-MgF2 film durability evaluations that included tape peel, fold, thermal cycle, and AO exposure testing. Polymer coupon preparation is described as well as ITO-MgF2 film deposition equipment, procedures and film characterization. Durability testing methods are also described. The pre- and post-test condition of the films is assessed visually, microscopically, and electrically. Results show that at 500 ITO - 9 vol% MgF2 film is suitable to protect polymer surfaces, such as those used in space-inflatable structures of the PowerSphere microsatellite concept, during a 1-year Earth orbiting mission. Future plans for ground-based and orbital testing of this film are also discussed.

  5. Selective scattering polymer dispersed liquid crystal film for light enhancement of organic light emitting diode.

    PubMed

    Jiang, Jinghua; McGraw, Greg; Ma, Ruiqing; Brown, Julie; Yang, Deng-Ke

    2017-02-20

    We developed a novel light enhancing film for an organic light emitting diode (OLED) based on polymer dispersed liquid crystal (PDLC). In the film, the liquid crystal droplets are unidirectionally aligned along the film normal direction and exhibit selective scattering. The film scatters light emitted only in directions with large incident angles but not light emitted in directions with small incident angles. When the light is scattered, it changes propagation direction and exits the OLED. The PDLC film reduces the total internal reflection and thus can significantly increase the light efficiency of the OLED.

  6. Nano-organized collagen layers obtained by adsorption on phase-separated polymer thin films.

    PubMed

    Zuyderhoff, Emilienne M; Dupont-Gillain, Christine C

    2012-01-31

    The organization of adsorbed type I collagen layers was examined on a series of polystyrene (PS)/poly(methyl methacrylate) (PMMA) heterogeneous surfaces obtained by phase separation in thin films. These thin films were prepared by spin coating from solutions in either dioxane or toluene of PS and PMMA in different proportions. Their morphology was unraveled combining the information coming from X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle measurements. Substrates with PMMA inclusions in a PS matrix and, conversely, substrates with PS inclusions in a PMMA matrix were prepared, the inclusions being either under the form of pits or islands, with diameters in the submicrometer range. The organization of collagen layers obtained by adsorption on these surfaces was then investigated. On pure PMMA, the layer was quite smooth with assemblies of a few collagen molecules, while bigger assemblies were found on pure PS. On the heterogeneous surfaces, it appeared clearly that the diameter and length of collagen assemblies was modulated by the size and surface coverage of the PS domains. If the PS domains, either surrounding or surrounded by the PMMA phase, were above 600 nm wide, a heterogeneous distribution of collagen was found, in agreement with observations made on pure polymers. Otherwise, fibrils could be formed, that were longer compared to those observed on pure polymers. Additionally, the surface nitrogen content determined by XPS, which is linked to the protein adsorbed amount, increased roughly linearly with the PS surface fraction, whatever the size of PS domains, suggesting that adsorbed collagen amount on heterogeneous PS/PMMA surfaces is a combination of that observed on the pure polymers. This work thus shows that PS/PMMA surface heterogeneities can govern collagen organization. This opens the way to a better control of collagen supramolecular organization at interfaces, which could in turn allow cell

  7. Radiation tolerant polymeric films through the incorporation of small molecule dopants in the polymer matrix

    SciTech Connect

    Lenhart, Joseph L.; Cole, Phillip J.; Cole, Shannon M.; Schroeder, John L.; Belcher, Michael E.

    2008-01-15

    Radiation induced conductivity (RIC) in semicrystalline polyethylene terephthalate (PET) films can be reduced by incorporating small molecule electron traps into the polymer. The electron traps contained an aromatic core with strong electron withdrawing functionality pendant to the core and were incorporated into the PET film by immersing the polymer in a solution of dopant and solvent at elevated temperatures. The chemical functionality of the electron trapping molecule and the number of pendant functional groups had a strong impact on the equilibrium doping level and the most effective doping solvent. In addition, all of the electron traps exhibited effectiveness at reducing the RIC. The technique of incorporating small molecule dopants into the polymer matrix in order to reduce the RIC can potentially be exploited with other polymers films and coatings utilized in electronics devices such as encapsulants, conformal coatings, and polymeric underfills.

  8. 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.

  9. 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.

  10. Synthesis and characterization of nanoscale polymer films grafted to metal surfaces

    NASA Astrophysics Data System (ADS)

    Galabura, Yuriy

    Anchoring thin polymer films to metal surfaces allows us to alter, tune, and control their biocompatibility, lubrication, friction, wettability, and adhesion, while the unique properties of the underlying metallic substrates, such as magnetism and electrical conductivity, remain unaltered. This polymer/metal synergy creates significant opportunities to develop new hybrid platforms for a number of devices, actuators, and sensors. This present work focused on the synthesis and characterization of polymer layers grafted to the surface of metal objects. We report the development of a novel method for surface functionalization of arrays of high aspect ratio nickel nanowires/micronails. The polymer "grafting to" technique offers the possibility to functionalize different segments of the nickel nanowires/micronails with polymer layers that possess antagonistic (hydrophobic/hydrophilic) properties. This method results in the synthesis of arrays of Ni nanowires and micronails, where the tips modified with hydrophobic layer (polystyrene) and the bottom portions with a hydrophilic layer (polyacrylic acid). The developed modification platform will enable the fabrication of switchable field-controlled devices (actuators). Specifically, the application of an external magnetic field and the bending deformation of the nickel nanowires and micronails will make initially hydrophobic surface more hydrophilic by exposing different segments of the bent nanowires/micronails. We also investigate the grafting of thin polymer films to gold objects. The developed grafting technique is employed for the surface modification of Si/SiO2/Au microprinted electrodes. When electronic devices are scaled down to submicron sizes, it becomes critical to obtain uniform and robust insulating nanoscale polymer films. Therefore, we address the electrical properties of polymer layers of poly(glycidyl methacrylate) (PGMA), polyacrylic acid (PAA), poly(2-vinylpyridine) (P2VP), and polystyrene (PS) grafted to

  11. Influence of macromolecular architecture on necking in polymer extrusion film casting process

    SciTech Connect

    Pol, Harshawardhan; Banik, Sourya; Azad, Lal Busher; Doshi, Pankaj; Lele, Ashish; Thete, Sumeet

    2015-05-22

    Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al{sup 1} wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking.{sup 1}D. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996)

  12. Structural, Thermal, Electrical and Magnetic Properties of PVA: Mn2+ and PVA: Ni2+ Polymer Films

    NASA Astrophysics Data System (ADS)

    Reddy, M. Obula; Buddhudu, S.

    2011-11-01

    Polymer films of PVA:Mn2+ and PVA: Ni2+ have been synthesized by a solution casting method in order to study their structural, thermal, dielectric, electrical and magnetic properties. The semi-crystalline nature of the polymer films has been confirmed from XRD analysis. The FTIR analysis confirms the complex formation of the polymer with the metal ions. Thermal stability of these films has been investigated based on the measurement of TG-DTA profiles. Dielectric studies of these films have also been carried out at various set temperatures in the frequency from 100 Hz to 1 MHz for carrying out impedance spectroscopy analysis to evaluate the electrical conductivity which arises due to a single conduction mechanism and thus and thus to have a single semicircle pattern from these polymer films. The direct current (dc) electrical conductivity increases with an increase in the temperature and it could be due to high mobility of free charges (polarons and free-ions) at higher temperatures. The conductivity trend follows the Arrhenius equation and the activation energy for PVA: Mn2+ has been found to be at 0.83 eV and 2.193eV and for PVA: Ni2+ has been found to be 0.71 eV. Both the polymer films that are investigated here have revealed paramagnetic nature based on the trends noticed in the magnetic characteristic profiles.

  13. Influence of macromolecular architecture on necking in polymer extrusion film casting process

    NASA Astrophysics Data System (ADS)

    Pol, Harshawardhan; Banik, Sourya; Azad, Lal Busher; Thete, Sumeet; Doshi, Pankaj; Lele, Ashish

    2015-05-01

    Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al1 wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking.1D. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996).

  14. Spin-Casting Polymer Brush Films for Stimuli-Responsive and Anti-Fouling Surfaces.

    PubMed

    Xu, Binbin; Feng, Chun; Hu, Jianhua; Shi, Ping; Gu, Guangxin; Wang, Lei; Huang, Xiaoyu

    2016-03-01

    Surfaces modified with amphiphilic polymers can dynamically alter their physicochemical properties in response to changes of their environmental conditions; meanwhile, amphiphilic polymer coatings with molecular hydrophilic and hydrophobic patches, which can mitigate biofouling effectively, are being actively explored as advanced coatings for antifouling materials. Herein, a series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was employed to prepare uniform thin films by spin-casting. The properties of these films were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quartz crystal microbalance (QCM). AFM showed smooth surfaces for all films with the roughness less than 2 nm. The changes in water contact angle and C/O ratio (XPS) evidenced the enrichment of PEG or PS chains at film surface after exposed to selective solvents, indicative of stimuli- responsiveness. The adsorption of proteins on PEG functionalized surface was quantified by QCM and the results verified that amphiphilic polymer brush films bearing PEG chains could lower or eliminate protein-material interactions and resist to protein adsorption. Cell adhesion experiments were performed by using HaCaT cells and it was found that polymer brush films possess good antifouling ability.

  15. Direct Synthesis of Crystalline MoS2 Thin Films on Large Area, Stretchable Polymer Surfaces (Preprint)

    DTIC Science & Technology

    2015-05-15

    AFRL-RX-WP-JA-2016-0239 DIRECT SYNTHESIS OF CRYSTALLINE MoS2 THIN FILMS ON LARGE AREA, STRETCHABLE POLYMER SURFACES (PREPRINT...AREA, STRETCHABLE POLYMER SURFACES (PREPRINT) 5a. CONTRACT NUMBER FA8650-11-D-5800-0005 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F...devices on flexible polymer substrates. 15. SUBJECT TERMS MoS2 films, PDMS substrates, photothermal, amorphous material, polymer substrate 16

  16. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films

    NASA Astrophysics Data System (ADS)

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-04-01

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu3+ and Tb3+) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

  17. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

    PubMed

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-04-18

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu(3+) and Tb(3+)) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

  18. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films

    PubMed Central

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-01-01

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu3+ and Tb3+) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces. PMID:27086735

  19. Thin metal film-polymer composite for efficient optoacoustic generation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lee, Taehwa; Guo, L. Jay

    2016-03-01

    Photoacoustic (PA) conversion of metal film absorbers is known to be inefficient because of their low thermal expansion and high light reflectance, as compared to polymeric materials containing light absorbing fillers. Specifically, the PA signal for metal films is typically an order of magnitude lower than those for PDMS-based composites consisting of carbon materials such as carbon blacks, carbon nanotubes, and carbon fibers. However, the carbon-PDMS composites have several disadvantages, e.g., difficulty in controlling film thickness, aggregation of the carbon fillers, and poor patternablility. To overcome these issues and achieve comparable PA amplitudes, a polymer-metal film composite was developed consisting of a thin metal absorber and adjacent transparent polymer layers. The proposed structure shows efficient PA conversion. The measured PA amplitude of the metal film composite is an order of magnitude higher than that of metal-only samples, and comparable to those of the carbon-PDMS composites. The enhanced PA conversion is accomplished by using metal film of a few tens of nanometers, which greatly facilitates heat transfer from the metal film to the surrounding polymers. Moreover, integrating the metal film composite with a photonic cavity can compensate light absorption loss of the thinner metal film. Theoretical and experimental analysis is conducted for understanding the mechanism behind such improvement. This strategy could be implemented for spatial PA signal patterns, especially for deep tissue PA imaging of implants or image-guiding tools. Furthermore, this approach also provides a guideline for designing photoacoustic transmitters and contrast agents.

  20. Engineering the Crystalline Morphology of Polymer Thin Films via Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Jeong, Hyuncheol; Arnold, Craig; Priestley, Rodney

    Thin-film growth via physical vapor deposition (PVD) has been successfully exploited for the delicate control of film structure for molecular and atomic systems. The application of such a high-energetic process to polymeric film growth has been challenged by chemical degradation. However, recent development of Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique opened up a way to deposit a variety of macromolecules in a PVD manner. Here, employing MAPLE technique to the growth of semicrystalline polymer thin films, we show the engineering of crystalline film morphology can be achieved via manipulation of substrate temperature. This is accomplished by exploiting temperature effect on crystallization kinetics of polymers. During the slow film growth crystallization can either be permitted or suppressed, and crystal thickness can be tuned via temperature modulation. In addition, we report that the crystallinity of polymer thin films may be significantly altered with deposition temperature in MAPLE processing. We expect that this ability to manipulate crystallization kinetics during polymeric film growth will open the possibility to engineer structure in thin film polymeric-based devices in ways that are difficult by other means.

  1. Surface plasmon resonance image sensor module of spin-coated silver film with polymer layer.

    PubMed

    Son, Jung-Han; Lee, Dong Hun; Cho, Yong-Jin; Lee, Myung-Hyun

    2013-11-01

    Prism modules of 20 nm-, 40 nm-, and 60 nm-thick spin-coated silver films both without and with an upper 100 nm-thick spin-coated polymer layer were fabricated for surface plasmon resonance (SPR) image sensor applications. The prism modules were applied to an SPR image sensor system. The coefficients of determination (R2s) for the 20 nm-, 40 nm- and 60 nm-thick silver films without the polymer layer were 0.9231, 0.9901, and 0.9889, respectively, and with the polymer layer 0.9228, 0.9951, and 0.9880, respectively when standard ethanol solutions with 0.1% intervals in the range of 20.0% to 20.5% were applied. The upper polymer layer has no effect on the R2. The prism modules of the 40-nm-thick spin-coated silver films had the highest R2 value of approximately 0.99. The durability of the 40 nm-thick spin-coated silver film with the 100 nm-thick polymer layer is much better than that without the upper low-loss polymer layer. The developed SPR image sensor module of the 40 nm-thick spin-coated silver film with the upper 100 nm-thick low-loss polymer film is expected to be a very cost-effective and robust solution because the films are formed at low temperatures in a short period of time without requiring a vacuum system and are very durable.

  2. Electron-beam-deposited thin polymer films - Electrical properties vs bombarding current.

    NASA Technical Reports Server (NTRS)

    Babcock, L. E.; Christy, R. W.

    1972-01-01

    Polymer films about 150 A thick, deposited on glass substrates by electron bombardment of tetramethyltetraphenyltrisiloxane, were studied, after being sandwiched between evaporated aluminum electrodes, the top one semitransparent. The capacitance, conductance, and photoconductance of the sandwiches were measured at room temperature as a function of the electron bombarding current which formed the polymer. The polymer thickness was obtained independently from Christy's (1960) empirical formula for the rate of formation. The obtained results indicate that, with increasing bombarding current, the polymer undergoes an increase in both crosslinking bonds and dangling bonds. Exposure to air drastically reduces the density of dangling bonds, but does not affect the crosslinking.

  3. Measuring Exciton Diffusion in Conjugated Polymer Films with Super-resolution Microscopy

    NASA Astrophysics Data System (ADS)

    Penwell, Samuel; Ginsberg, Lucas; Noriega Manez, Rodrigo; Ginsberg, Naomi

    2015-03-01

    Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion microscopy. STED is typically used in biology with well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated STED in conjugated polymer films of MEH-PPV and CN-PPV by taking care to first understand the film's photophysical properties. This new approach provides a way to study exciton diffusion by utilizing subdiffraction optical excitation volumes. In this way, we will obtain a spatiotemporal map of exciton distributions that will help to correlate the energetic landscape to film morphology at the nanoscale. This research is supported in part by the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF), made possible in part by the American Recovery and Reinvestment Act of 2009, administered by ORISE-ORAU under Contract No. DE-AC05-06.

  4. Deposition of Tungsten Thin Films on Flexible Polymer Substrates by Direct-Current Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Huo, Zhenxuan; Jiao, Xiangquan; Zhong, Hui; Shi, Yu

    2015-11-01

    We have investigated thin tungsten films deposited on polymer substrates by direct-current magnetron sputtering under different conditions. Unlike tungsten films deposited on rigid substrates, films on polymer substrates grew at appropriate sputtering power, low sputtering pressure, and low substrate temperature. High sputtering power results in tungsten films with good crystal orientation, compact microstructure, and low electrical resistivity. However, high-power sputtering damages the polymer substrates. Enhancing sputtering pressure substantially degrades tungsten orientation and increases electrical resistivity. Furthermore, a slight increase in substrate temperature results in tungsten films with good crystal orientation, a dense microstructure, and low electrical resistivity. Nonetheless, a high substrate temperature results in soft and deformed polymer substrates; this degrades tungsten crystal orientation and substantially roughens tungsten films. On the basis of this study, compact and flat tungsten films with low electrical resistivity can be obtained at a sputtering power of 69 W, a sputtering pressure of 1 Pa, a substrate temperature of 100°C, and a distance between target and substrate of 60 mm.

  5. Heat transport in polymer thin films for micro/nano-manufacturing

    NASA Astrophysics Data System (ADS)

    Hung, Ming-Tsung

    The rapid growth in micro/nanotechnology has opened a great opportunity for polymer thin films and polymer nanocomposites. Thermal management or thermal effects in those applications need to be carefully examined. For example, the local heating in electron-beam lithography, emersion lithography, and scanning near field optical lithography may cause the degradation of photoresists and reduce the resolution. The development of many organic electronics, polymer micro-electro-mechanical-systems (MEMS) devices, and polymer nanocomposites may require the knowledge of heat transport in micro/nano-sized polymers. Thermolithography, a novel lithography, uses controlled localized heating to transfer patterns and requires the thermal conductivity data to control. It is of considerable scientific and technological interests for study heat transport in polymer thin films. Unlike bulk polymers that can be measured using commercially available instruments, polymer thin films are difficult to measure. In this manuscript, we develop the measurement techniques suitable for measuring thermal conductivity of polymer thin films and polymer nanocomposites. Using a microfabricated membrane-based device, we study the heat conduction in photoresists at difference process stages. This data is used in our thermolithography study, where we use microheater to study the kinetic of crosslinking reaction of photoresist. The feasibility of thermolithography and potential three dimensional micro/nano-fabrication is presented. The uniqueness of thermolithography is also demonstrated by patterning amorphous fluoropolymers. A modified hot-wire technique is used to measure the thermal conductivity of graphite nanoplatelet (GNP) reinforced nanocomposites, one of the promising candidates for multifunctional materials. Thermal interface resistance in GNP nanocomposites is investigated, which shows a strong effect on energy transport in the nanocomposites and can be diminished through surface treatment.

  6. Identification of different type of polymers in plastics waste.

    PubMed

    Siddiqui, Mohammad N; Gondal, Mohammad A; Redhwi, Halim H

    2008-09-01

    The main goal of this work was to develop and test advanced techniques for the instant identification of different type of polymers in post-consumer plastics. In order to accomplish this task, infrared (IR), X-ray diffraction (XRD), differential scanning calorimetric (DSC) and laser induced breakdown spectroscopic (LIBS) techniques were applied. The following six model plastics were identified in this study. Low-density polyethylene (LDPE), High-density polyethylene (HDPE), Polypropylenes (PP), Polystyrene (PS), Polyethylene terephthalate (PET) and Polyvinyl chloride (PVC) along with few randomly selected plastics waste such as water bottle and cap, water cups, yogurt container and coke bottle were studied. IR has shown the fingerprinting of polymer types present in plastics waste. The XRD analysis helps to provide characteristic spectral lines whose intensities vary with the type of each constituent polymer. The DSC method provided the different crystalline melting temperature, glass transition, and onset temperature for the peaks and the percent crystallinity data single out different polymers. The ratio of LIBS signals intensities of carbon and hydrogen atoms were employed for the finger printing of the different family of plastics. The combined use of IR, XRD, DSC and LIBS techniques yielded very useful and effective results for plastic waste management.

  7. Fabrication of Dye-Dispersed Optical-Quality Polymer Films by Coprecipitation of Cyanine Dye with Polymers

    NASA Astrophysics Data System (ADS)

    Hiraga, Takashi; Takarada, Shigeru; Tanaka, Norio; Hayamizu, Kikuko; Moriya, Tetsuo

    1994-09-01

    3,3'-Diethyloxadicarbocyanine iodide (DODCI)-dissolved polymer powders were formed by coprecipitation of DODCI with polymers [poly(methyl methacrylate) (PMMA), poly(2-hydroxypropyl methacrylate) (PHPMA), etc.]. An acetone solution of DODCI in which a purified polymer was also dissolved was injected into a large amount of n-hexane. The precipitated powder in n-hexane was filtered and then dried under ultrahigh vacuum (UHV), and formed into a thin film by a hot-press method [Hiraga et al.: Chem. Lett. (1990) 2255]. Another method for preparing a powder by coprecipitation has successfully been developed using a vacuum process. The acetone solution of DODCI and polymer was directly injected into UHV from the liquid phase through a modified needle valve. Deposits were formed on a heat-controlled substrate through quick evaporation of a carrier solvent and they were hot-pressed to produce a thin transparent film. Condensed states of DODCI associates in these films have been analyzed by optical absorption and emission, small-angle X-ray scattering (SAXS), and NMR spectroscopy. A new technique to control the arrangement of dye associates in three-dimensional space has been proposed.

  8. Polarized absorption spectra of aromatic radicals in stretched polymer film. 3. Radical ions of acridine and phenazine

    SciTech Connect

    Sekigucki, K.; Hiratsuka, H.; Tanizaki, Y.; Hatano, Y.

    1980-02-21

    Radical anions and cations of acridine and phenazine have been prepared in polymer film by ..gamma..-ray irradiation at 77 K. For the preparation of radical anions the sample was incorporated into polyethylene film by sec-butylamine, while for radical cations poly(vinyl chloride) film and sec-butyl chloride were used. Polarized absorption spectra of these radical ions have been measured in stretched polymer film and analyzed qualitatively in terms of molecular orbital calculations.

  9. Interfacial structure and electrical properties of transparent conducting ZnO thin films on polymer substrates.

    PubMed

    Lim, Young Soo; Kim, Dae Wook; Kang, Jong-Ho; Seo, Seul Gi; Kim, Bo Bae; Choi, Hyoung-Seuk; Seo, Won-Seon; Cho, Yong Soo; Park, Hyung-Ho

    2013-08-01

    The effects of polymer substrates on the interfacial structure and the thermal stability of Ga-doped ZnO (GZO) thin films were investigated. The GZO thin films were deposited on polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates by rf-magnetron sputtering at room temperature, and thermal stability tests of the GZO thin films on the polymer substrates were performed at 150°C up to 8 h in air. Electrical and structural characterizations of the GZO thin films on the PET and the PEN substrates were carried out, and the origins of the stable interfacial structure and the improved thermal stability of the GZO thin film on the PEN substrate were discussed.

  10. Anomalous Drag Reduction and Hydrodynamic Interactions of Nanoparticles in Polymer Nanocomposite Thin Films

    NASA Astrophysics Data System (ADS)

    Basu, Jaydeep; Begam, Nafisa; Chandran, Sivasurender; Sprung, Michael

    2015-03-01

    One of the central dogma of fluid physics is the no-slip boundary condition whose validity has come under intense scrutiny, especially in the fields of micro and nanofluidics. Although various studies show the violation of the no-slip condition its effect on flow of colloidal particles in viscous media has been rarely explored. Here we report unusually large reduction of effective drag experienced by polymer grafted nanoparticles moving through a highly viscous film of polymer, well above its glass transition temperature. The extent of drag reduction increases with decreasing temperature and polymer film thickness. We also observe apparent divergence of the wave vector dependent hydrodynamic interaction function of these nanoparticles with an anomalous power law exponent of ~ 2 at the lowest temperatures and film thickness. Such strong hydrodynamic interactions are not expected in polymer melts where these interactions are known to be screened to molecular dimensions. We provide evidence for the presence of large hydrodynamic slip at the nanoparticle-polymer interface and demonstrate its tunability with temperature and confinement. Our study suggests novel physics emerging in dynamics nanoparticles due to confinement and interface wettability in thin films of polymer nanocomposites.

  11. Experimental evidence of ultrathin polymer film stratification by AFM force spectroscopy.

    PubMed

    Delorme, Nicolas; Chebil, Mohamed Souheib; Vignaud, Guillaume; Le Houerou, Vincent; Bardeau, Jean-François; Busselez, Rémi; Gibaud, Alain; Grohens, Yves

    2015-06-01

    By performing Atomic Force Microscopy measurements of pull-off force as a function of the temperature, we were able to probe the dynamic of supported thin polystyrene (PS) films. Thermal transitions induce modifications in the surface energy, roughness and surface modulus that are clearly detected by AFM and related to PS chain relaxation mechanisms. We demonstrated the existence of three transition temperatures that can be associated to the relaxation of polymer chains located at different depth regions within the polymer film. Independently of the film thickness, we have confirmed the presence of a region of high mobility for the polymer chains at the free interface. The thickness of this region is estimated to be above 7nm. The detection of a transition only present for film thicker than the gyration radius Rg is linked to the dynamics of polymer chains in a bulk conformation (i.e. not in contact with the free interface). We claim here that our results demonstrate, in agreement with other techniques, the stratification of thin polymer film depth profile in terms of relaxation behavior.

  12. A laminated polymer film formulation for enteric delivery of live vaccine and probiotic bacteria.

    PubMed

    de Barros, João M S; Scherer, Timothy; Charalampopoulos, Dimitrios; Khutoryanskiy, Vitaliy V; Edwards, Alexander D

    2014-07-01

    Live bacterial cells (LBCs) are administered orally as attenuated vaccines to deliver biopharmaceutical agents and as probiotics to improve gastrointestinal (GI) health. However, LBCs present unique formulation challenges and must survive GI antimicrobial defenses including gastric acid after administration. We present a simple new formulation concept, termed polymer film laminate (PFL). LBCs are ambient dried onto cast acid-resistant enteric polymer films that are then laminated together to produce a solid oral dosage form. LBC of a model live bacterial vaccine and a probiotic were dried directly onto a cast film of enteric polymer. The effectiveness at protecting dried cells in a simulated gastric fluid (SGF, pH 2.0) depended on the composition of enteric polymer film used, with a blend of ethylcellulose plus Eudragit L100 55 providing greater protection from acid than Eudragit alone. However, although PFL made from blended polymer films completely released low-molecular-weight dye into intestinal conditions (pH 7.0), they failed to release LBCs. In contrast, PFL made from Eudragit alone successfully protected dried probiotic or vaccine LBC from SGF for 2 h, and subsequently released all viable cells within 60 min of transfer into simulated intestinal fluid. Release kinetics could be controlled by modifying the lamination method.

  13. Hydrothermal Synthesis and Processing of Barium Titanate Nanoparticles Embedded in Polymer Films.

    PubMed

    Toomey, Michael D; Gao, Kai; Mendis, Gamini P; Slamovich, Elliott B; Howarter, John A

    2015-12-30

    Barium titanate nanoparticles embedded in flexible polymer films were synthesized using hydrothermal processing methods. The resulting films were characterized with respect to material composition, size distribution of nanoparticles, and spatial location of particles within the polymer film. Synthesis conditions were varied based on the mechanical properties of the polymer films, ratio of polymer to barium titanate precursors, and length of aging time between initial formulations of the solution to final processing of nanoparticles. Block copolymers of poly(styrene-co-maleic anhydride) (SMAh) were used to spatially separate titanium precursors based on specific chemical interactions with the maleic anhydride moiety. However, the glassy nature of this copolymer restricted mobility of the titanium precursors during hydrothermal processing. The addition of rubbery butadiene moieties, through mixing of the SMAh with poly(styrene-butadiene-styrene) (SBS) copolymer, increased the nanoparticle dispersion as a result of greater diffusivity of the titanium precursor via higher mobility of the polymer matrix. Additionally, an aminosilane was used as a means to retard cross-linking in polymer-metalorganic solutions, as the titanium precursor molecules were shown to react and form networks prior to hydrothermal processing. By adding small amounts of competing aminosilane, excessive cross-linking was prevented without significantly impacting the quality and composition of the final barium titanate nanoparticles. X-ray diffraction and X-ray photoelectron spectroscopy were used to verify nanoparticle compositions. Particle sizes within the polymer films were measured to be 108 ± 5 nm, 100 ± 6 nm, and 60 ± 5 nm under different synthetic conditions using electron microscopy. Flexibility of the films was assessed through measurement of the glass transition temperature using dynamic mechanical analysis. Dielectric permittivity was measured using an impedance analyzer.

  14. Engineering polymer-fullerene thin films and solar cells with external fields

    NASA Astrophysics Data System (ADS)

    Cabral, Joao

    2014-03-01

    Trace amounts of nanoparticles, including fullerenes, can impart stability to thin polymer films against dewetting by the combined effects of pinning the contact lines of dewetting holes and by effectively altering the polymer-substrate interaction. Polymer nanocomposite (meta)stable thin films can yield well-defined morphologies from uniform to spinodal-like, via spontaneous polymer-nanoparticle phase separation and crystallization. Confinement breaks the structural isotropy and generally causes (partial) segregation of components orthogonally to the film surface. Surface energy patterning can thus modulate composition and morphology, both in plane and normal to the surface. Further, UV-visible, and even background, light exposure, in both solutions and melts, is shown to tune the solution stucture and morphology of dewetting and phase separating polymer-fullerene thin films. Neutron reflectivity allows us to locate the various constituents within the film. We find a coupling of fullerene photo-sensitivity and both self-assembly processes which results in controlled pattern formation, and we illustrate the potential with a model polymer-fullerene circuit pattern. We then translate this approach into the directed assembly of energy harvesting bulk heterojunctions thin films. Indeed, a key challenge to the commercialization of organic solar cells remains the achievement of morphological stability, particularly under thermal stress conditions. The directed assembly a blend polymer:PC60BM solar cells via a simple light processing step results in a 10-100 fold increase in device thermal stability and, under certain conditions, enhanced device performance. The enhanced stability is linked to the light-induced oligomerisation of PC60BM that effectively hinders diffusion and crystallization in blends. This effect appears to be general and promises to be an effective and cost-effective strategy to optimize fullerene-based solar cell performance.

  15. Formation of hybrid films from perylenediimide-labeled core-shell silica-polymer nanoparticles.

    PubMed

    Ribeiro, Tânia; Fedorov, Aleksander; Baleizão, Carlos; Farinha, José Paulo S

    2013-07-01

    We prepared water-dispersible core-shell nanoparticles with a perylenediimide-labeled silica core and a poly(butyl methacrylate) shell, for application in photoactive high performance coatings. Films cast from water dispersions of the core-shell nanoparticles are flexible and transparent, featuring homogeneously dispersed silica nanoparticles, and exhibiting fluorescence under appropriate excitation. We characterized the film formation process using nanoparticles where the polymer shell has been labeled with either a non-fluorescent N-benzophenone derivative (NBen) or a fluorescent phenanthrene derivative (PheBMA). We used Förster resonance energy transfer (FRET) from PheBMA to NBen to follow the interparticle interdiffusion of the polymer anchored to the silica surface that occurs after the dried dispersions are annealing above the glass transition temperature of the polymer. By calculating the evolution of the FRET quantum efficiency with annealing time, we could estimate the approximate fraction of mixing (fm) between polymer from neighbor particles, and from this, the apparent diffusion coefficients (Dapp) for this process. For long annealing times, the limiting values of fm are slightly lower than for films of pure PBMA particles at similar temperatures (go up to 80% of total possible mixing). The corresponding diffusion coefficients are also very similar to those reported for films of pure PBMA, indicating that the fact that the polymer chains are anchored to the silica particles does not significantly hinder the diffusion process during the initial part of the mixing process. From the temperature dependence of the diffusion coefficients, we found an effective activation energy for diffusion of Ea=38 kcal/mol, very similar to the value obtained for particles of the same polymer without the silica core. With these results, we show that, although the polymer is grafted to the silica surface, polymer interdiffusion during film formation is not significantly

  16. Elastic Properties of Lysozyme Confined in Nanoporous Polymer Films

    NASA Astrophysics Data System (ADS)

    Wang, Haoyu; Akcora, Pinar

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. It is known that confined media provide a protective environment to the encapsulated proteins and prevent diffusion of the denaturant. In this study, different types of proteins (streptavidin, lysozyme and fibrinogen) were chemically attached into the nanopores of poly(methyl methacrylate) thin films. Heterogeneous flat surfaces with varying cylinder pore sizes (10-50 nm) were used to confine proteins of different sizes and shapes. Stiffness of protein functionalized nanopores was measured in nanoindentation experiments. Our results showed that streptavidin behaved more stiffly when pore dimension changed from micron to nanosize. Further, it was found that lysozyme confined within nanopores showed higher specific bioactivity than proteins on flat surfaces. These results on surface elasticity and protein activity may help in understanding protein interactions with surfaces of different topologies and chemistry.

  17. Synthesis of novel electrically conducting polymers: Potential conducting Langmuir-Blodgett films and conducting polymers on defined surfaces

    NASA Technical Reports Server (NTRS)

    Zimmer, Hans

    1993-01-01

    Based on previous results involving thiophene derived electrically conducting polymers in which it was shown that thiophene, 3-substituted thiophenes, furans, and certain oligomers of these compounds showed electrical conductivity after polymerization. The conductivity was in the order of up to 500 S/cm. In addition, these polymers showed conductivity without being doped and most of all they were practically inert toward ambient conditions. They even could be used in aqueous media. With these findings as a guide, a number of 3-long-chain-substituted thiophenes and 1-substituted-3-long-chain substituted pyrrols were synthesized as monomers for potential polymeric electrically conducting Langmuir-Blodgett films.

  18. Directed self-assembly of block copolymers for high breakdown strength polymer film capacitors

    SciTech Connect

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

    2016-03-04

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

  19. Directed self-assembly of block copolymers for high breakdown strength polymer film capacitors

    DOE PAGES

    Samant, Saumil P.; Grabowski, Christopher A.; Kisslinger, Kim; ...

    2016-03-04

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

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

    PubMed

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

    2016-03-01

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

  1. Quantitative Assessment of Coumarin-Containing Polymer Film's Capability for Photoalignment of Liquid Crystals

    SciTech Connect

    Kim, C.; Wallace, J.U.; Trajkovska, A.; Ou, J.J.; Chen, S.H.

    2007-12-12

    The photoalignment of a nematic fluid, E-7, and a glassy-nematic oligofluorene, F(MB)5, was investigated on films of Polymers 1 and 2 in the parallel regime. Polarized absorption spectroscopy and computational chemistry were employed to characterize coumarin monomer's and dimer's molar extinction coefficients and to locate absorption dipoles as parallel to their long molecular axes. Moreover, their orientational order parameters, S_m and S_d, were experimentally determined as functions of the extent of dimerization. Higher S_d and Y_d, coumarin dimer's mole fraction, were achieved in films of Polymer 1 than in Polymer 2 because of the greater coumarin mobility of the former. The ability of a coumarin-containing photoalignment film to orient a spin-cast F(MB)5 film was found to improve with increasing Y_d S_d to an extent comparable to that of a rubbed polyimide film. Because of the relatively short lengths of its constituent molecules, E-7 was oriented equally well on both polymer films regardless of the Y_d S_d values.

  2. Graphene Oxide-Polymer Composite Langmuir Films Constructed by Interfacial Thiol-Ene Photopolymerization

    NASA Astrophysics Data System (ADS)

    Luo, Xiaona; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Zhang, Lexin; Zhou, Jingxin; Li, Bingbing

    2017-02-01

    The effective synthesis and self-assembly of graphene oxide (GO) nanocomposites are of key importance for a broad range of nanomaterial applications. In this work, a one-step chemical strategy is presented to synthesize stable GO-polymer Langmuir composite films by interfacial thiol-ene photopolymerization at room temperature, without use of any crosslinking agents and stabilizing agents. It is discovered that photopolymerization reaction between thiol groups modified GO sheets and ene in polymer molecules is critically responsible for the formation of the composite Langmuir films. The film formed by Langmuir assembly of such GO-polymer composite films shows potential to improve the mechanical and chemical properties and promotes the design of various GO-based nanocomposites. Thus, the GO-polymer composite Langmuir films synthesized by interfacial thiol-ene photopolymerization with such a straightforward and clean manner, provide new alternatives for developing chemically modified GO-based hybrid self-assembled films and nanomaterials towards a range of soft matter and graphene applications.

  3. Graphene Oxide-Polymer Composite Langmuir Films Constructed by Interfacial Thiol-Ene Photopolymerization.

    PubMed

    Luo, Xiaona; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Zhang, Lexin; Zhou, Jingxin; Li, Bingbing

    2017-12-01

    The effective synthesis and self-assembly of graphene oxide (GO) nanocomposites are of key importance for a broad range of nanomaterial applications. In this work, a one-step chemical strategy is presented to synthesize stable GO-polymer Langmuir composite films by interfacial thiol-ene photopolymerization at room temperature, without use of any crosslinking agents and stabilizing agents. It is discovered that photopolymerization reaction between thiol groups modified GO sheets and ene in polymer molecules is critically responsible for the formation of the composite Langmuir films. The film formed by Langmuir assembly of such GO-polymer composite films shows potential to improve the mechanical and chemical properties and promotes the design of various GO-based nanocomposites. Thus, the GO-polymer composite Langmuir films synthesized by interfacial thiol-ene photopolymerization with such a straightforward and clean manner, provide new alternatives for developing chemically modified GO-based hybrid self-assembled films and nanomaterials towards a range of soft matter and graphene applications.

  4. Porous structures of polymer films prepared by spin coating with mixed solvents under humid condition.

    PubMed

    Park, Min Soo; Joo, Wonchul; Kim, Jin Kon

    2006-05-09

    We investigate the effects of interfacial energy between water and solvent as well as polymer concentration on the formation of porous structures of polymer films prepared by spin coating of cellulose acetate butyrate (CAB) in mixed solvent of tetrahydrofuran (THF) and chloroform under humid condition. The interfacial energy between water and the solvent was gradually changed by the addition of chloroform to the solvent. At a high polymer concentration (0.15 g/cm3 in THF), porous structures were limited only at the top surfaces of CAB films, regardless of interfacial energies, due to the high viscosity of the solution. At a medium concentration (approximately 0.08 g/cm3 in THF), CAB film had relatively uniform pores at the top surface and very small pores inside the film because of the mixing of the water droplets with THF solution. When chloroform was added to THF, pores at the inner CAB film had a comparable size with those at the top surface because of the reduced degree of the mixing between the water droplets and the mixed solvent. A further decrease in polymer concentration (0.05 g/cm3 in THF) caused the final films to have a two-layer porous structure, and the size of pores at each layer was almost the same.

  5. Optical field-induced surface relief formation on chalcogenide and azo-benzene polymer films

    NASA Astrophysics Data System (ADS)

    Teteris, J.; Gertners, U.

    2012-08-01

    The dependence of the surface relief formation in amorphous As2S3 and Disperse Red 1dye grafted polyurethane polymer films on the polarization state of recording light was studied. It is shown that the direction of mass transport on the film surface is determined by the direction of light electric vector and photoinduced anisotropy in the film. We propose a photoinduced dielectropfhoretic model to explain the photoinduced mass transport in amorphous films. Model is based on the photoinduced softening of the matrix, formation of defects with enhanced or decreased polarizability, and their drift under the electrical field gradient of light.

  6. Preparation of [100] oriented SrTiO3 thin films on flexible polymer sheets

    NASA Astrophysics Data System (ADS)

    Nishikawa, Hiroaki; Morita, Yusuke; Kusunoki, Masanobu; Hontsu, Shigeki; Tanaka, Hidekazu; Endo, Tamio

    2014-01-01

    In this study, we prepared a uniaxially oriented oxide on a flexible polymer substrate. We first grew [100] oriented SrTiO3 (STO) on a MgO(100) substrate. After bonding the STO film to a poly(ethylene naphthalete) (PEN) sheet with a photoresist, we etched the MgO substrate with a phosphoric acid solution to transfer the oxide film to the PEN sheet. The thin (300 nm) STO films did not crack after release, even after bending the sheet around a rod with a 1 cm radius, while the thicker (800 nm) films did. Ultimately, this process could be adapted to prepare a flexible epitaxial oxide.

  7. Structure-property relation in HPMC polymer films plasticized with Sorbitol

    NASA Astrophysics Data System (ADS)

    Prakash, Y.; Somashekarappa, H.; Mahadevaiah, Somashekar, R.

    2013-06-01

    A correlation study on physical and mechanical properties of Hydroxy propyl-methylcellulose (HPMC) polymer films plasticized with different weight ratio of Sorbitol, prepared using solution casting method, was carried out using wide angle X-ray technique and universal testing machine. It is found that the crystallanity decreases as the concentration of Sorbitol increases up to a certain concentration and there afterwards increases. Measured Physical Properties like tensile strength decreases and elongation (%) increases indicating increase in the flexibility of the films. These observations confirm the correlation between microstructal parameters and mechanical properties of films. These films are suitable for packaging food products.

  8. Deviations of the glass transition temperature in amorphous conjugated polymer thin films

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Osuna Orozco, Rodrigo; Wang, Tao

    2013-08-01

    The deviations of the glass transition temperature (Tg) in thin films of an amorphous conjugated polymer poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) are reported. Monotonic and nonmonotonic Tg deviations are observed in TFB thin films supported on Si-SiOx and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), respectively. A three-layer model is developed to fit both monotonic and nonmonotonic Tg deviations in these films. A 5-nm PEDOT:PSS capping layer was not found to be effective to remove the free-surface effect in Si-SiOx supported TFB films.

  9. A new generation of electrochemical supercapacitors based on layer-by-layer polymer films

    NASA Astrophysics Data System (ADS)

    Christinelli, Wania Ap.; Gonçalves, Roger; Pereira, Ernesto C.

    2016-01-01

    Here we report supercapacitors fabricated with the layer-by-layer (LBL) technique using two polymers, namely poly(o-methoxyaniline) (POMA) and poly(3-thiophene acetic acid) (PTAA). The electrochemical performances of POMA/PTAA supercapacitors were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results were compared with POMA casting film. The specific capacitance of LBL films increases almost linearly with a number of bilayers which were not observed for POMA casting films. The results of this investigation demonstrate that the self-doping effect between POMA and PTAA can change the properties on films and can be successfully used as a supercapacitor technology.

  10. Controlling self-assembly and ordering of block polymer nanostructures in thin films

    NASA Astrophysics Data System (ADS)

    Luo, Ming

    Block polymers have garnered significant attention in the past few decades due to their ability to self-assemble into a boundless array of structures such as spheres, cylinders, gyroid, and lamellae. The sizes of the periodical structures typically are 5 - 100 nm, making them ideal for emerging nanotechnologies, such as nanolithography, nanotemplating, nanoporous membranes, and photonics devices. Many of these applications require thin film geometries, in which the block polymers form well-ordered nanostructures and precisely controlled domain orientations. Understanding the factors that affect thin film phase behavior and being able to control the nanostructures, domain orientation, and domain ordering in thin film is essential to realizing the full potential of these unique materials. In this dissertation, I describe significant efforts to manipulate the block polymer thin film structures, direct the nanostructure ordering, and understand the connection between the macromolecular molecular structures and the block polymer properties. First, substrate surface modification with chlorosilane was employed to manipulate the nanostructure of poly(styrene- b-isoprene-b-styrene) (SIS) thin films. A morphological transformation from parallel cylinders to hexagonally perforated lamellae (HPL) was identified, in a high-throughput fashion, using gradient methods. The gradient methods are highly adaptable for the possible universal manipulation of thin film nanostructures. Second, rastering solvent vapor annealing - soft shear method was developed and demonstrated as a simple, yet highly effective method to achieve macroscopic alignment of SIS cylinders. This method substantially improves on previous approaches by using simple instrumentation to unlock an array of alignment patterns with a variety of self-assembling polymers and provides feasibility and flexibility for practical industrial production. Next, the interfacial mixing characteristics of tapered block polymer were

  11. Critical Material Attributes of Strip Films Loaded With Poorly Water-Soluble Drug Nanoparticles: II. Impact of Polymer Molecular Weight.

    PubMed

    Krull, Scott M; Ammirata, Jennifer; Bawa, Sonia; Li, Meng; Bilgili, Ecevit; Davé, Rajesh N

    2017-02-01

    Recent work established polymer strip films as a robust platform for delivery of poorly water-soluble drug particles. However, a simple means of manipulating rate of drug release from films with minimal impact on film mechanical properties has yet to be demonstrated. This study explores the impact of film-forming polymer molecular weight (MW) and concentration on properties of polymer films loaded with poorly water-soluble drug nanoparticles. Nanoparticles of griseofulvin, a model Biopharmaceutics Classification System class II drug, were prepared in aqueous suspension via wet stirred media milling. Aqueous solutions of 3 viscosity grades of hydroxypropyl methylcellulose (14, 21, and 88 kDa) at 3 viscosity levels (∼9500, ∼12,000, and ∼22,000 cP) were mixed with drug suspension, cast, and dried to produce films containing griseofulvin nanoparticles. Few differences in film tensile strength or elongation at break were observed between films within each viscosity level regardless of polymer MW despite requiring up to double the time to achieve 100% drug release. This suggests film-forming polymer MW can be used to manipulate drug release with little impact on film mechanical properties by matching polymer solution viscosity. In addition, changing polymer MW and concentration had no negative impact on drug content uniformity or nanoparticle redispersibility.

  12. Styrene-Butadiene Co-Polymer Based Highly Conducting and Flexible Polymer Composite Film with Low Percolation Threshold

    NASA Astrophysics Data System (ADS)

    Mathew, Anisha Mary; Neena, P.

    2011-10-01

    Conducting polymer composites are finding novel applications in various fields especially in device technology. In this work an effort has been made to synthesize polyaniline-synthetic rubber (Styrene-butadiene rubber) composite via ex-situ technique and its electrochemical properties are investigated. Highly conducting emeraldine form of polyaniline (20 S/cm) is prepared by the oxidative polymerization of aniline in aqueous acidic (CSA) media using ammonium peroxydisulfate as oxidizing agent. These composite films are characterized by UV-Visible spectroscopy to investigate their optical properties. The dc conductivity studies indicate that these composite films show extremely low percolation threshold.

  13. Positron Annihilation Spectroscopy Of High Performance Polymer Films Under CO{sub 2} Pressure

    SciTech Connect

    Quarles, C. A.; Klaehn, John R.; Peterson, Eric S.; Urban-Klaehn, Jagoda M.

    2011-06-01

    Positron annihilation Lifetime and Doppler broadening measurements are reported for six polymer films as a function of carbon dioxide (CO{sub 2}) absolute pressure ranging from 0 to 45 psi. Since the polymer films were thin and did not absorb all positrons, corrections were made in the lifetime analysis for the absorption of positrons in the positron source and sample holder using the Monte Carlo transport code MCNP. The studied polymers are found to behave differently from each other. Some polymers form positronium and others, such as the polyimide structures, do not. For those polymers that form positronium an interpretation in terms of free volume is possible; for those that don't form positronium, further work is needed to determine how best to describe the behavior in terms of the bulk positron annihilation parameters. A few of the studied polymers exhibit changes in positron lifetime and intensity under CO{sub 2} pressure which may be described by the Henry or Langmuir sorption models, while the positron response of other polymers is rather insensitive to the CO{sub 2} pressure. The results demonstrate the usefulness of positron annihilation spectroscopy in investigating the sorption of CO{sub 2} into various polymers at pressures up to about 3 atm (45psi).

  14. Photochemical Immobilization of Polymers on a Surface: Controlling Film Thickness and Wettability.

    PubMed

    Carroll, Gregory T; Turro, Nicholas J; Mammana, Angela; Koberstein, Jeffrey T

    2017-03-15

    In this manuscript we demonstrate the control of film thickness and surface wettability in the photochemical immobilization of poly (vinyl alcohol) (PVA) to a self-assembled monolayer (SAM) containing a phthalimide chromophore. Surface attachment is characterized by ellipsometry and contact angle measurements. The wettability of the resulting films is shown to depend on the chemical composition of the polymer. The film thickness is shown to depend on the irradiation time and molecular weight of the polymer. Using a photo-mask, micro-patterns of polymers can be grafted to the SAM. The photo-patterned surface can be "developed" by coating with a thin layer of a mixture containing poly (styrene) (PS) and triphenylsulfonium triflate. This article is protected by copyright. All rights reserved.

  15. Time-dependent charge distributions in polymer films under electron beam irradiation

    SciTech Connect

    Yasuda, Masaaki; Kainuma, Yasuaki; Kawata, Hiroaki; Hirai, Yoshihiko; Tanaka, Yasuhiro; Watanabe, Rikio; Kotera, Masatoshi

    2008-12-15

    The time-dependent charge distribution in polymer film under electron beam irradiation is studied by both experiment and numerical simulation. In the experiment, the distribution is measured with the piezoinduced pressure wave propagation method. In the simulation, the initial charge distribution is obtained by the Monte Carlo method of electron scattering, and the charge drift in the specimen is simulated by taking into account the Poisson equation, the charge continuity equation, Ohm's law, and the radiation-induced conductivity. The results obtained show that the negative charge deposited in the polymer film, whose top and bottom surfaces are grounded, drifts toward both grounded electrodes and that twin peaks appear in the charge distribution. The radiation-induced conductivity plays an important role in determining the charge distribution in the polymer films under electron beam irradiation.

  16. Suppression of quantum dot blinking in DTT-doped polymer films

    PubMed Central

    Antelman, Josh; Ebenstein, Yuval; Dertinger, Thomas; Michalet, Xavier; Weiss, Shimon

    2009-01-01

    In this report we evaluate the emission properties of single quantum dots embedded in a thin, thiol containing polymer film. We report the suppression of quantum dot blinking leading to a continuous photon flux from both organic and water soluble quantum dots and demonstrate their application as robust fluorescent point sources for ultrahigh resolution localization. In addition, we apply the polymer coating to cell samples immunostained with antibody conjugated QDs and show that fluorescence intensity from the polymer embedded cells shows no sign of degradation after 67 hours of continuous excitation. The reported thin polymer film coating may prove advantageous for immuno-cyto/histo-chemistry as well as for the fabrication of quantum dot containing devices requiring a reliable and stable photon source (including a single photon source) or stable charge characteristics while maintaining intimate contact between the quantum dot and the surrounding matrix. PMID:20161096

  17. Porous polymer films templated by marangoni flow-induced water droplet arrays.

    PubMed

    Cai, Yangjun; Zhang Newby, Bi-min

    2009-07-07

    In this article, we report the development of a novel, simple, and cost-effective method for fabricating porous polymer films with controllable interpore distances, pore sizes, and arrangements using water droplets induced by Marangoni flow as templates. First, a spread-thin ethanol film on a partially water-wettable substrate is exposed to a humid airflow, facilitating the evaporation and recession of the ethanol film. Meanwhile, water in the airflow condenses on the ethanol film and accumulates near the receding contact line, which induces the formation of water fingers at the receding contact line and, finally, ordered arrays of water droplets after detachment. The formation of the hexagonal and square arrays of water droplets is due to the pinning and sliding of the water fingers on the silicone oxide (SiOx) and silicon (Si) substrates, respectively. By varying the thickness of the ethanol film spread on the Si substrate, the sliding velocity of water fingers can be tuned, subsequently leading to the fabrication of other arrangements. The interdroplet distance and droplet size can be dependently controlled by tuning the humidity of the airflow. The ordered arrays of water droplets on the substrate are then utilized to fabricate porous polymer films by dip-coating the substrate with a polystyrene solution. Films with hexagonal and square (and other arrangements) arrays of pores are fabricated on the silicon oxide (SiOx) and silicon (Si) substrates, respectively. The pore size can also be independently tuned by further condensation or evaporation of formed water droplets, leading to porous polymer films with both close- and non-close-packed arrays of pores. The ordered porous polymer films can be further used as templates for fabricating metal post patterns.

  18. Flexible n-Type High-Performance Thermoelectric Thin Films of Poly(nickel-ethylenetetrathiolate) Prepared by an Electrochemical Method.

    PubMed

    Sun, Yuanhui; Qiu, Lin; Tang, Liangpo; Geng, Hua; Wang, Hanfu; Zhang, Fengjiao; Huang, Dazhen; Xu, Wei; Yue, Peng; Guan, Ying-Shi; Jiao, Fei; Sun, Yimeng; Tang, Dawei; Di, Chong-An; Yi, Yuanping; Zhu, Daoben

    2016-05-01

    Flexible thin films of poly(nickel-ethylenetetrathiolate) prepared by an electrochemical method display promising n-type thermoelectric properties with the highest ZT value up to 0.3 at room temperature. Coexistence of high electrical conductivity and high Seebeck coefficient in this coordination polymer is attributed to its degenerate narrow-bandgap semiconductor behavior.

  19. Polyelectrolyte multilayer film coating and stability at the surfaces of oral prosthesis base polymers: an in vitro and in vivo study.

    PubMed

    Etienne, O; Picart, C; Taddei, C; Keller, P; Hubsch, E; Schaaf, P; Voegel, J C; Haikel, Y; Ogier, J A; Egles, C

    2006-01-01

    A new type of coating involving a layer-by-layer technique has been recently reported. This coating is composed of a polyelectrolyte multilayer film that confers specific properties on surfaces to which it is applied. Here, we studied the applicability of such a technique to the coating of oral prostheses, by first testing the construction of polyelectrolyte multilayer films on several polymers used in oral prosthesis bases, and, subsequently, by studying the stability of these coatings in vitro, in human saliva, and in vivo in a rat model. We demonstrated that the multilayered films are able to coat the surfaces of all tested polymers completely, thus increasing their wettability. We also showed that saliva does not degrade the film after 7 days in vitro and after 4 days in vivo. Taken together, our results establish that the layer-by-layer technique is suitable for the coating of oral devices.

  20. The structure and charge-storage capacitance of carbonized films based on silicon-polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Zavyalov, S. A.; Kulova, T. L.; Kupriyanov, L. Yu.; Roginskaya, Yu. E.; Skundin, A. M.

    2008-12-01

    New film materials for electrodes of lithium batteries were synthesized and studied. Thin-film silicon-polymer composites were prepared by vacuum cocondensation of silicon and the monomer onto a substrate cooled with liquid nitrogen; the polymerization and formation of the nanostructured composite were performed at room temperature. The films were carbonized by vacuum annealing. The film composition and microstructure were studied by AFM, SEM, Raman spectroscopy, and X-ray spectral microanalysis. It was shown that the polymer matrix became almost fully carbonized because of pyrolysis. The silicon concentration in the films varied from 2 to 5 at %. The concentration of silicon nanoparticles on carbonized film surfaces was ˜106 cm-2. Electrochemical experiments with lithium insertion into the composite films were performed in standard three-electrode cells under galvanostatic conditions. The specific capacitance of the films was measured. It was shown that the samples were capable of long-term cycling; the capacitance decreased by only 6% during the first 200 cycles; after 250 cycles, the capacitance still exceeded 80% of its initial value. The mechanism of lithium insertion into the films was discussed. It was concluded that long-term stability during cycling was caused by the presence of silicon both as nanoparticles and in the atomically dispersed form.

  1. Metal-loaded polymer films for chemical sensing of ES&H-related pollutants

    SciTech Connect

    Martin, S.J.; Frye, G.C.

    1997-03-01

    This report summarizes the results of a Laboratory Directed Research and Development (LDRD) effort to study and model surface acoustic wave (SAW) devices for environmental applications. The response of polymer-coated SAW devices to temperature changes and polymer vapor absorption is examined. A perturbational approach is used to relate velocity and attenuation responses to film translational and strain modes generated by the SAW. Two distinct regimes of film behavior arise, causing different SAW responses. For glassy films, displacement is nearly uniform across the film thickness, varying only in the direction of propagation. A model developed to predict velocity and attenuation in this regime, reduces to the familiar Tiersten (Wohltjen) equation for purely elastic films. For elastomeric (rubbery) films, inertial effects cause a phase lag to occur across the film for shear displacements. A model to account for these cross-film displacement gradients predicts a characteristic resonant response when the film phase shift reaches np/2, where n is an odd integer. These model predictions are compared with measured responses from polyisobutylene-coated SAW devices as temperature is varied and during exposure to high vapor concentrations.

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

    PubMed

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

    2008-12-02

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

  3. Polymer Thin Film Transistors: High Electron Mobility and Ambipolar Charge Transport

    NASA Astrophysics Data System (ADS)

    Jenekhe, Samson; Babel, Amit

    2004-03-01

    Along with high performance unipolar FETs, knowledge of ambipolar charge transport in conjugated polymers and organic semiconductors is important to realize the ultimate vision of all-plastic complementary integrated circuits for logic and memory applications. We present herein studies of electron transport in n-type conjugated ladder polymer, poly(benzobisimidazobenzophenanthroline) (BBL) in which we observed field-effect electron mobilities as high as 0.05-0.1 cm^2/Vs.^[1] We have also developed new ambipolar thin film transistors based on blends of BBL and copper phthalocyanine (CuPc). Ambipolar hole mobilities were as high as 2.0 × 10-4 cm^2/Vs while electron mobilities were up to 3.0 × 10-5 cm^2/Vs. Transmission electron microscopy showed crystallization of CuPc in the α -crystal form within the semicrystalline BBL matrix. On prolonged treatment of the blend FETs in methanol, unipolar hole mobilities as high as 2.0 × 10-3 cm^2/Vs were observed, comparable to hole mobilities in thermally evaporated CuPc FETs. [1] Babel, A.; Jenekhe, S. A. J. Am. Chem. Soc. 2003, 125, 13656.

  4. Radiation damage in polymer films from grazing-incidence X-ray scattering measurements

    SciTech Connect

    Vaselabadi, Saeed Ahmadi; Shakarisaz, David; Ruchhoeft, Paul; Strzalka, Joseph; Stein, Gila E.

    2016-02-16

    Grazing-incidence X-ray scattering (GIXS) is widely used to analyze the crystallinity and nanoscale structure in thin polymer films. However, ionizing radiation will generate free radicals that initiate cross-linking and/or chain scission, and structural damage will impact the ordering kinetics, thermodynamics, and crystallinity in many polymers. We report a simple methodology to screen for beam damage that is based on lithographic principles: films are exposed to patterns of x-ray radiation, and changes in polymer structure are revealed by immersing the film in a solvent that dissolves the shortest chains. The experiments are implemented with high throughput using the standard beam line instrumentation and a typical GIXS configuration. The extent of damage (at a fixed radiation dose) depends on a range of intrinsic material properties and experimental variables, including the polymer chemistry and molecular weight, exposure environment, film thickness, and angle of incidence. The solubility switch for common polymers is detected within 10-60 sec at ambient temperature, and we verified that this first indication of damage corresponds with the onset of network formation in glassy polystyrene and a loss of crystallinity in polyalkylthiophenes. Therefore, grazing-incidence x-ray patterning offers an efficient approach to determine the appropriate data acquisition times for any GIXS experiment.

  5. Radiation damage in polymer films from grazing-incidence X-ray scattering measurements

    DOE PAGES

    Vaselabadi, Saeed Ahmadi; Shakarisaz, David; Ruchhoeft, Paul; ...

    2016-02-16

    Grazing-incidence X-ray scattering (GIXS) is widely used to analyze the crystallinity and nanoscale structure in thin polymer films. However, ionizing radiation will generate free radicals that initiate cross-linking and/or chain scission, and structural damage will impact the ordering kinetics, thermodynamics, and crystallinity in many polymers. We report a simple methodology to screen for beam damage that is based on lithographic principles: films are exposed to patterns of x-ray radiation, and changes in polymer structure are revealed by immersing the film in a solvent that dissolves the shortest chains. The experiments are implemented with high throughput using the standard beam linemore » instrumentation and a typical GIXS configuration. The extent of damage (at a fixed radiation dose) depends on a range of intrinsic material properties and experimental variables, including the polymer chemistry and molecular weight, exposure environment, film thickness, and angle of incidence. The solubility switch for common polymers is detected within 10-60 sec at ambient temperature, and we verified that this first indication of damage corresponds with the onset of network formation in glassy polystyrene and a loss of crystallinity in polyalkylthiophenes. Therefore, grazing-incidence x-ray patterning offers an efficient approach to determine the appropriate data acquisition times for any GIXS experiment.« less

  6. Ultraviolet and infrared femtosecond laser induced periodic surface structures on thin polymer films

    SciTech Connect

    Rebollar, Esther; Castillejo, Marta; Vazquez de Aldana, Javier R.; Moreno, Pablo

    2012-01-23

    This work demonstrates the formation of femtosecond laser induced periodic surface structures (LIPSS) by multipulse irradiation with the fundamental and 3rd harmonic of a linearly polarized Ti:sapphire laser (795 and 265 nm) on thin films of the polymers poly (ethylene terephthalate), poly (trimethylene terephthalate), and poly (carbonate bisphenol A) prepared by spin-coating. LIPSS, inspected by atomic force microscopy, are formed upon multiple pulse UV and IR irradiation with wavelength-sized period in a narrow range of fluences below the ablation threshold. Control and tunability of the size and morphology of the periodic structures become thus possible ensuring photochemical integrity of polymer films.

  7. Luminescent guest-host composite films based on an azomethine dye in different matrix polymers

    NASA Astrophysics Data System (ADS)

    Marin, Luminita; Zabulica, Andrei; Moleavin, Ioana-Andreea

    2014-12-01

    New hybrid guest/host composite films obtained by dispersing a light-emitting azomethine dimer into three different matrix polymers have been studied. Poly(methyl methacrylate) (PMMA), UDEL polysulfone (PSU) and chitosan were chosen as host matrix. Differential scanning calorimetry, polarized light microscopy, scanning electron microscopy and atomic force microscopy measurements revealed the composite morphology and their thermal properties. UV-vis and fluorescence spectroscopy indicated the influence of polymer matrix on the azomethine dye optical properties. The composite films exhibited strong photoluminescence emission when excited with maximum absorption wavelength. It was concluded that polysulfone is a good candidate in guest/host composite obtaining.

  8. Photoreversible optical data recording in films of amorphous azo dye-containing polymers

    SciTech Connect

    Simonov, A N; Uraev, D V; Shibaev, Valerii P; Kostromin, S G

    2002-02-28

    The photoreversible properties of films of amorphous azo-containing polymers (AAPs) are studied theoretically and experimentally. The control of the sign of a photoinduced addition {Delta}n{sup ind} to the refractive index of the polymer by changing polarisation of the incident light is demonstrated. A theoretical model of photoinduced processes in AAP films is proposed, which takes into account the orientation diffusion of trans-isomers of azo dyes, and simplified analytic approaches describing the photoorientation dynamics in AAPs are considered. The theoretical results are in good agreement with our experimental data. (laser applications and other topics in quantum electronics)

  9. Transient self-interaction of light in a liquid-crystal polymer film containing azodye molecules

    SciTech Connect

    Simonov, A N

    1999-07-31

    Transient self-interaction of low-power He - Ne laser radiation (1 < 50 mW cm{sup -2} ) in a liquid-crystal polymer film containing chemically bound azodye molecules was observed experimentally. The self-interaction occurred in the region of a temperature-induced phase transition in the polymer film and was accompanied by the formation of quasi-periodic ring-shaped structures in the distribution of the transmitted light intensity. (this issue is dedicated to the memory of s a akhmanov)

  10. Spontaneous photoinduced patterning of azo-dye polymer films: the facts

    SciTech Connect

    Hubert, Christophe

    2007-08-15

    We describe the spontaneous photoinduced patterning of azo-dye polymer films. We have observed that the illumination of an azo-dye polymer film by a uniform single laser beam with normal incidence leads to a self-structurization process that results in the formation of well-ordered submicrometer-sized structures whose organization depends on the light polarization direction. A modulation depth as high as 100 nm can be achieved. The influence of several experimental parameters on the structure formation is studied. Results are discussed and confronted to different models and phenomena already investigated in the literature. A physical origin to this peculiar photopatterning process is proposed.

  11. Ultrafast formation of air-processable and high-quality polymer films on an aqueous substrate

    NASA Astrophysics Data System (ADS)

    Noh, Jonghyeon; Jeong, Seonju; Lee, Jung-Yong

    2016-08-01

    Polymer solar cells are attracting attention as next-generation energy sources. Scalable deposition techniques of high-quality organic films should be guaranteed to realize highly efficient polymer solar cells in large areas for commercial viability. Herein, we introduce an ultrafast, scalable, and versatile process for forming high-quality organic films on an aqueous substrate by utilizing the spontaneous spreading phenomenon. This approach provides easy control over the thickness of the films by tuning the spreading conditions, and the films can be transferred to a variety of secondary substrates. Moreover, the controlled Marangoni flow and ultrafast removal of solvent during the process cause the films to have a uniform, high-quality nanomorphology with finely separated phase domains. Polymer solar cells were fabricated from a mixture of polymer and fullerene derivatives on an aqueous substrate by using the proposed technique, and the device exhibited an excellent power conversion efficiency of 8.44 %. Furthermore, a roll-to-roll production system was proposed as an air-processable and scalable commercial process for fabricating organic devices.

  12. Ultrafast formation of air-processable and high-quality polymer films on an aqueous substrate

    PubMed Central

    Noh, Jonghyeon; Jeong, Seonju; Lee, Jung-Yong

    2016-01-01

    Polymer solar cells are attracting attention as next-generation energy sources. Scalable deposition techniques of high-quality organic films should be guaranteed to realize highly efficient polymer solar cells in large areas for commercial viability. Herein, we introduce an ultrafast, scalable, and versatile process for forming high-quality organic films on an aqueous substrate by utilizing the spontaneous spreading phenomenon. This approach provides easy control over the thickness of the films by tuning the spreading conditions, and the films can be transferred to a variety of secondary substrates. Moreover, the controlled Marangoni flow and ultrafast removal of solvent during the process cause the films to have a uniform, high-quality nanomorphology with finely separated phase domains. Polymer solar cells were fabricated from a mixture of polymer and fullerene derivatives on an aqueous substrate by using the proposed technique, and the device exhibited an excellent power conversion efficiency of 8.44 %. Furthermore, a roll-to-roll production system was proposed as an air-processable and scalable commercial process for fabricating organic devices. PMID:27507624

  13. A flexible tactile-feedback touch screen using transparent ferroelectric polymer film vibrators

    NASA Astrophysics Data System (ADS)

    Ju, Woo-Eon; Moon, Yong-Ju; Park, Cheon-Ho; Choi, Seung Tae

    2014-07-01

    To provide tactile feedback on flexible touch screens, transparent relaxor ferroelectric polymer film vibrators were designed and fabricated in this study. The film vibrator can be integrated underneath a transparent cover film or glass, and can also produce acoustic waves that cause a tactile sensation on human fingertips. Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] polymer was used as the relaxor ferroelectric polymer because it produces a large strain under applied electric fields, shows a fast response, and has excellent optical transparency. The natural frequency of this tactile-feedback touch screen was designed to be around 200-240 Hz, at which the haptic perception of human fingertips is the most sensitive; therefore, the resonance of the touch screen at its natural frequency provides maximum haptic sensation. A multilayered relaxor ferroelectric polymer film vibrator was also demonstrated to provide the same vibration power at reduced voltage. The flexible P(VDF-TrFE-CTFE) film vibrators developed in this study are expected to provide tactile sensation not only in large-area flat panel displays, but also in flexible displays and touch screens.

  14. The theory and design of piezoelectric/pyroelectric polymer film sensors for biomedical engineering applications.

    PubMed

    Brown, L F

    1989-01-01

    The unique properties of piezoelectric/pyroelectric polymers offer many new opportunities for biomedical engineering sensor applications. Since their discovery nearly 20 years ago, the polymer films have been used for many novel switching and sensor applications. Despite the prodigious exposure from many recent publications describing piezo film applications, methods of sensor fabrication and circuit interfacing still elude most engineers. This paper is presented as a tutorial guide to applying piezo polymers to biomedical engineering applications. A review of the fundamentals of piezoelectricity/pyroelectricity in piezo polymers is first presented. Their material properties are contrasted with piezoelectric ceramic materials. Some advantages and disadvantages of the films for biomedical sensors are discussed. Specific details on the fabrication of piezo film sensors are presented. Methods are described for forming, cutting, and mounting film sensors, and making lead connections. A brief discussion of equivalent circuit models for the design and simulation of piezoelectric/pyroelectric sensors is included, as well as common circuit interface techniques. Finally, several sources are recommended for further information on a variety of biomedical sensor applications.

  15. Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity

    PubMed Central

    Gu, Cheng; Huang, Ning; Wu, Yang; Xu, Hong; Jiang, Donglin

    2015-01-01

    Porous organic polymers allow the integration of various π-units into robust porous π-networks, but they are usually synthesized as unprocessable solids with poor light-emitting performance as a result of aggregation-related excitation dissipation. Herein, we report a general strategy for the synthesis of highly emissive photofunctional porous polymer films on the basis of a complementary scheme for the structural design of aggregation-induced-emissive π-systems. We developed a high-throughput and facile method for the direct synthesis of large-area porous thin films at the liquid–electrode interface. The approach enables the preparation of microporous films within only a few seconds or minutes and allows precise control over their thickness with sub-nanometer precision. By virtue of rapid photoinduced electron transfer, the thin films can detect explosives with enhanced sensitivity to low parts-per-million levels in a selective manner. PMID:26234636

  16. Assembly of poly(dopamine) films mixed with a nonionic polymer.

    PubMed

    Zhang, Yan; Thingholm, Bo; Goldie, Kenneth N; Ogaki, Ryosuke; Städler, Brigitte

    2012-12-21

    Poly(dopamine) (PDA) coatings have recently attracted considerable interest for a variety of applications. Here, we investigate the film deposition of dopamine mixed with a nonionic polymer (i.e., poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), and poly(N-vinyl pyrrolidone) (PVP)) onto silica substrates using X-ray photoelectron spectroscopy and quartz crystal microbalance. Furthermore, we assess the possibility of coating silica colloids to yield polymer capsules and liposomes with these mixtures. We found that mixed PDA/PEG and PDA/PVA films are deposited without the need for a covalent linker such as an amine or thiol. We also discovered the first material, namely, PVP, that can suppress PDA film assembly. These fundamental findings give further insight into PDA film properties and contribute to establish PDA as a widely applicable coating.

  17. Amphiphilic Fluorinated Polymer Nanoparticle Film Formation and Dissolved Oxygen Sensing Application

    NASA Astrophysics Data System (ADS)

    Gao, Yu; Zhu, Huie; Yamamoto, Shunsuke; Miyashita, Tokuji; Mitsuishi, Masaya

    2016-04-01

    Fluorinated polymer nanoparticle films were prepared by dissolving amphiphilic fluorinated polymer, poly (N-1H, 1H-pentadecafluorooctylmethacrylamide) (pC7F15MAA) in two miscible solvents (AK-225 and acetic acid). A superhydrophobic and porous film was obtained by dropcasting the solution on substrates. With higher ratios of AK-225 to acetic acid, pC7F15MAA was densified around acetic acid droplets, leading to the formation of pC7F15MAA nanoparticles. The condition of the nanoparticle film preparation was investigated by varying the mixing ratio or total concentration. A highly sensitive dissolved oxygen sensor system was successfully prepared utilizing a smart surface of superhydrophobic and porous pC7F15MAA nanoparticle film. The sensitivity showed I0/I40 = 126 in the range of dissolved oxygen concentration of 0 ~ 40 mg L-1. The oxygen sensitivity was compared with that of previous reports.

  18. Characterization of electrophoretic suspension for thin polymer film deposition

    NASA Astrophysics Data System (ADS)

    Mladenova, D.; Weiter, M.; Stepanek, P.; Ouzzane, I.; Vala, M.; Sinigersky, V.; Zhivkov, I.

    2012-03-01

    The optical absorption and fluorescence spectra of poly [2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] toluene solutions and 50:50% toluene/acetonitrile suspensions show clearly distinguishable differences (e.g., peak broadening and shifting), which could be used for characterization of suspensions with different acetonitrile content. The dynamic light scattering (DLS) measurement of the suspensions prepared showed a particle size of 90 nm. Thin films with thicknesses of about 400 nm were prepared by electrophoretic deposition (EPD) and spin coating. As the films are very soft, a contactless optical profilometry techique based on chromatic aberration was used to measure their thickness. AFM imaging of spin coated and EPD films revealed film roughness of 20÷40 nm and 40÷80 nm, respectively. The EPD film roughness seems to be less than the suspension particle size obtained by DLS, probably due to the partial film dissolving by the toluene present in the suspension.

  19. Linearly and circularly polarized laser photoinduced molecular order in azo dye doped polymer films

    NASA Astrophysics Data System (ADS)

    Saad, Bendaoud

    2017-03-01

    Photo-induced behavior of Azo Disperse one (AZD1) doped Poly(Methyl MethAcrylate) (PMMA) using both linear and circular polarized light is studied. The anisotropy is not erased by the circular polarization light. The circular polarization light combined with relatively long lifetime of the cis state in azo dye doped polymers activate all transverse directions of the angular hole burning through the spot in the film inducing anisotropy. Under circular polarized light, there is no orientation perpendicularly to the helex described by the rotating electric field vector, trans molecules reorients in the propagation direction of the pump beam. The polarization state of the probe beam after propagation through the pumped spot depends strongly on the angle of incidence of both pump and probe beams on the input face. In the case where circular polarized pump and probe beams are under the same angle of incidence, the probe beam "sees" anisotropic film as if it is isotropic. Results of this work shows the possibility to reorient azobenzene-type molecules in two orthogonal directions using alternately linearly and circularly polarized beams.

  20. Tough, high performance, addition-type thermoplastic polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a high linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

  1. Hydrophobic but hygroscopic polymer films--identifying interfacial species and understanding water ingress behavior.

    PubMed

    Hsiao, Erik; Barnette, Anna L; Bradley, Laura C; Kim, Seong H

    2011-11-01

    The hydrophobic but hygroscopic nature of polydimethylsiloxane (PDMS) with quaternary ammonium cationic side chains adsorbed on a SiO(2) surface was investigated with sum frequency generation vibration spectroscopy (SFG) and attenuated total reflectance infrared spectroscopy (ATR-IR). PDMS with cationic side chains, named cationic polymer lubricant (CPL), forms a self-healing boundary lubrication film on SiO(2). It is interesting that CPL films are externally hydrophobic but internally hydrophilic. The comparison of SFG and ATR-IR data revealed that the methyl groups of the PDMS backbone are exposed at the film/air interface and the cationic side groups and counterions are embedded within the film. The hydrophobicity must originate from the surface CH(3) groups, while the ionic groups inside the film must be responsible for water uptake. The surface hydrophobicity can alleviate the capillary adhesion while the hygroscopic property enhances the mobility and self-healing capability of the CPL boundary lubrication film.

  2. Unfolding type gastroretentive film of Cinnarizine based on ethyl cellulose and hydroxypropylmethyl cellulose.

    PubMed

    Verma, Shakuntla; Nagpal, Kalpana; Singh, S K; Mishra, D N

    2014-03-01

    The present work was based on the development and characterization of unfolding type gastro retentive dosage form appropriate for controlled release of Cinnarizine (CNZ), a drug with narrow therapeutic window. The drug loaded polymer film of biological macromolecules, i.e., ethyl cellulose (EC) and hydroxypropylmethyl cellulose (HPMC K15) was folded into hard gelatin capsules. The film was folded in different patterns for characterizing their unfolding behavior. The polymeric film revealed a fast release during the first hour followed by a more gradual drug release during a 12-h period following a non-Fickian diffusion process. Tensile strength of polymeric film was optimized using different amount (0.2-0.7 ml) of polyethylene glycol (PEG 400). Various physical parameters were studied for evaluating their performance as a gastroretentive dosage form. Drug and polymers were found to be compatible as revealed by differential scanning calorimetry (DSC) study and scanning electron micrograph (SEM) study revealed uniform dispersion of CNZ in polymeric matrices. The results indicate that unfolding type gastro retentive drug delivery system holds lots of potential for drug having stability problems in alkaline pH or are which mainly absorbed in acidic pH.

  3. Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers

    DTIC Science & Technology

    1994-05-31

    NLO Polymers 6. AUTHOm(m) R&T Code: 4132016 W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.Kumar,S.K. Dr. JoAnn MilUiken Tripathy. 7. PERFORMING...Polymers by W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.Kumar,S.K. Tripathy. Submitted to Macromolecules University of Massachusetts Lowell Department...FILMS OF A NOVEL POLYDIACETYLENE AS SECOND ORDER NLO POLYMERS W. H. Kim, B. Bihari+, R. Moody+, N. B. Kodali , J. Kumar+, and S. K. Tripathy, University

  4. Effect of Polymer Film Permeability on Retarding or Preventing Corrosion

    DTIC Science & Technology

    2010-02-01

    AGENCY NAME(S) AND ADDRESS(ES) 10 . SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved...Test: Experimental set up 2/19/2010 10 Experimental: test films Resin WVTR, g-25um/m2day PE (control): 20 Med. Perm film 1300 High perm film 4300...films 2/19/2010 18 Results: Effect of WVTR on Corrosion Corroded area vs WVTR y = -1.0694Ln(x) + 8.9058 R 2 = 0.98280 1 2 3 4 5 6 7 1 10 100 1000 10000

  5. Employment of the Rheological Characteristics of Polymer Solutions in Modeling Film Production

    NASA Astrophysics Data System (ADS)

    Al Joda, H. N. A.; Pyshnograi, G. V.; Shipovskaya, A. B.; Tregubova, Yu. B.; Zinovich, S. A.

    2016-11-01

    A mathematical model of the process of film formation from a polymer solution is proposed. The rheological parameters of the model were determined by comparing theoretical curves and experimental data for chitosan solutions measured in their simple shear flow. Dimensionless similarity criteria were found for the rheological characteristics of the process. The effect of these criteria on the velocity, concentration, and width of the film in relation to the distance from the die exit is estimated.

  6. Surface characteristics of a self-polymerized dopamine coating deposited on hydrophobic polymer films.

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhu, Baoku; Xu, Youyi

    2011-12-06

    This study aims to explore the fundamental surface characteristics of polydopamine (pDA)-coated hydrophobic polymer films. A poly(vinylidene fluoride) (PVDF) film was surface modified by dip coating in an aqueous solution of dopamine on the basis of its self-polymerization and strong adhesion feature. The self-polymerization and deposition rates of dopamine on film surfaces increased with increasing temperature as evaluated by both spectroscopic ellipsometry and scanning electronic microscopy (SEM). Changes in the surface morphologies of pDA-coated films as well as the size and shape of pDA particles in the solution were also investigated by SEM, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The surface roughness and surface free energy of pDA-modified films were mainly affected by the reaction temperature and showed only a slight dependence on the reaction time and concentration of the dopamine solution. Additionally, three other typical hydrophobic polymer films of polytetrafluoroethylene (PTFE), poly(ethylene terephthalate) (PET), and polyimide (PI) were also modified by the same procedure. The lyophilicity (liquid affinity) and surface free energy of these polymer films were enhanced significantly after being coated with pDA, as were those of PVDF films. It is indicated that the deposition behavior of pDA is not strongly dependent on the nature of the substrates. This information provides us with not only a better understanding of biologically inspired surface chemistry for pDA coatings but also effective strategies for exploiting the properties of dopamine to create novel functional polymer materials.

  7. Improved optical and electrical properties of rf sputtered Al doped ZnO films on polymer substrates by low-damage processes

    SciTech Connect

    Min, Hyung Seob; Yang, Min Kyu; Lee, Jeon-Kook

    2009-03-15

    Three types of low-damage radio-frequency (rf) magnetron sputtering processes--an interruptive process, a rotating cylindrical holder method, and an off-axis sputtering method--were designed and studied to reduce the film surface temperature during deposition. Low-damage sputtering processes were investigated to improve the resistivity and optical transmittance in the visible range of Al doped ZnO (AZO) thin films deposited on polymer substrates. In the case of the polyethersulfone substrate, AZO films with a resistivity of 1.0x10{sup -3} {omega} cm and an optical transmittance of 75% were obtained by the rotating repeat holder method during rf sputtering.

  8. Positron Annihilation Spectroscopy of High Performance Polymer Films under CO2 Pressure

    SciTech Connect

    C.A. Quarles; John R. Klaehn; Eric S. Peterson; Jagoda M. Urban-Klaehn

    2010-08-01

    Positron annihilation Lifetime and Doppler broadening measurements are reported for six polymer films as a function of carbon dioxide absolute pressure ranging from 0 to 45 psi. Since the polymer films were thin and did not absorb all positrons, corrections were made in the lifetime analysis for the absorption of positrons in the positron source and sample holder using the Monte Carlo transport code MCNP. Different polymers are found to behave differently. Some polymers studied form positronium and some, such as the polyimide structures, do not. For those samples that form positronium an interpretation in terms of free volume is possible; for those that don’t form positronium, further work is needed to determine how best to describe the behavior in terms of the bulk positron annihilation parameters. Some polymers exhibit changes in positron lifetime and intensity under CO2 pressure which may be described by the Henry or Langmuir sorption models, while the positron response of other polymers is rather insensitive to the CO2 pressure. The results demonstrate the usefulness of positron annihilation spectroscopy in investigating the sorption of CO2 into various polymers at pressures up to about 3 atm.

  9. Design and characterization of chitosan/zeolite composite films--Effect of zeolite type and zeolite dose on the film properties.

    PubMed

    Barbosa, Gustavo P; Debone, Henrique S; Severino, Patrícia; Souto, Eliana B; da Silva, Classius F

    2016-03-01

    Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance.

  10. Measuring electro-mechanical properties of thin films on polymer substrates

    PubMed Central

    Cordill, Megan J.; Glushko, O.; Kreith, J.; Marx, V.M.; Kirchlechner, C.

    2015-01-01

    In order to advance flexible electronic technologies it is important to study the electrical properties of thin metal films on polymer substrates under mechanical load. At the same time, the observation of film deformation and fracture as well as the stresses that are present in the films during straining are also crucial to investigate. To address both the electromechanical and deformation behavior of metal films supported by polymer substrates, in-situ 4 point probe resistance measurements were performed with in-situ atomic force microscopy imaging of the film surface during straining. The 4 point probe resistance measurements allow for the examination of the changes in resistance with strain, while the surface imaging permits the visualization of localized thinning and crack formation. Furthermore, in-situ synchrotron tensile tests provide information about the stresses in the film and show the yield stress where the deformation initiates and the relaxation of the film during imaging. A thin 200 nm Cu film on 23 μm thick PET substrate will be used to illustrate the combined techniques. The combination of electrical measurements, surface imaging, and stress measurements allow for a better understanding of electromechanical behavior needed for the improvement and future success of flexible electronic devices. PMID:26082564

  11. Bending and Fracture in Thin Polymer Films during Capillary Origami Assembly

    NASA Astrophysics Data System (ADS)

    Twohig, Timothy; Croll, Andrew

    Capillary origami uses liquid tension to bend thin films into useful shapes and structures. The ability to scale this process to the microscopic range has led to growing interest in capillary origami and many potential applications. Clearly, the creation of three dimensional structures from flat sheets depends deeply on a combination of properties: fluid tensions, film thickness, film modulus and importantly the film's fracture properties. Fractures in a film are a critical component of macroscopic origami but macroscopic methods for creating these fractures are not possible at the microscopic scale. We present an experimental investigation of the interplay of capillary forces and material properties in the creation of controlled fractures in thin polymer films. Specifically, we use capillary forces to lift and bend a thin polymer film to the point of fracture using a variety of film thicknesses and material properties and attempt to model the basic underlying physics. We observe the creation of delaminations and fractures at pre-determined sites that can be tailored to specific shapes to be utilized in capillary origami.

  12. Measuring electro-mechanical properties of thin films on polymer substrates.

    PubMed

    Cordill, Megan J; Glushko, O; Kreith, J; Marx, V M; Kirchlechner, C

    2015-04-02

    In order to advance flexible electronic technologies it is important to study the electrical properties of thin metal films on polymer substrates under mechanical load. At the same time, the observation of film deformation and fracture as well as the stresses that are present in the films during straining are also crucial to investigate. To address both the electromechanical and deformation behavior of metal films supported by polymer substrates, in-situ 4 point probe resistance measurements were performed with in-situ atomic force microscopy imaging of the film surface during straining. The 4 point probe resistance measurements allow for the examination of the changes in resistance with strain, while the surface imaging permits the visualization of localized thinning and crack formation. Furthermore, in-situ synchrotron tensile tests provide information about the stresses in the film and show the yield stress where the deformation initiates and the relaxation of the film during imaging. A thin 200 nm Cu film on 23 μm thick PET substrate will be used to illustrate the combined techniques. The combination of electrical measurements, surface imaging, and stress measurements allow for a better understanding of electromechanical behavior needed for the improvement and future success of flexible electronic devices.

  13. Flexible fluidic microchips based on thermoformed and locally modified thin polymer films.

    PubMed

    Truckenmüller, R; Giselbrecht, S; van Blitterswijk, C; Dambrowsky, N; Gottwald, E; Mappes, T; Rolletschek, A; Saile, V; Trautmann, C; Weibezahn, K-F; Welle, A

    2008-09-01

    This paper presents a fundamentally new approach for the manufacturing and the possible applications of lab on a chip devices, mainly in the form of disposable fluidic microchips for life sciences applications. The new technology approach is based on a novel microscale thermoforming of thin polymer films as core process. The flexibility not only of the semi-finished but partly also of the finished products in the form of film chips could enable future reel to reel processes in production but also in application. The central so-called 'microthermoforming' process can be surrounded by pairs of associated pre- and postprocesses for micro- and nanopatterned surface and bulk modification or functionalisation of the formed films. This new approach of microscale thermoforming of thin polymer film substrates overlaid with a split local modification of the films is called 'SMART', which stands for 'substrate modification and replication by thermoforming'. In the process, still on the unformed, plane film, the material modifications of the preprocess define the locations where later, then on the spatially formed film, the postprocess generates the final local modifications. So, one can obtain highly resolved modification patterns also on hardly accessible side walls and even behind undercuts. As a first application of the new technology, we present a flexible chip-sized scaffold for three dimensional cell cultivation in the form of a microcontainer array. The spatially warped container walls have been provided with micropores, cell adhesion micropatterns and thin film microelectrodes.

  14. Plasma surface modification of polymers

    NASA Technical Reports Server (NTRS)

    Hirotsu, T.

    1980-01-01

    Thin plasma polymerization films are discussed from the viewpoint of simplicity in production stages. The application of selective, absorbent films and films used in selective permeability was tested. The types of surface modification of polymers discussed are: (1) plasma etching, (2) surface coating by plasma polymerized thin films, and (3) plasma activation surface graft polymerization.

  15. Interaction of Nano-Sized Materials With Polymer Chains in Polymer-Nanocomposite Thin Films-An AFM Perspective

    NASA Astrophysics Data System (ADS)

    Verma, Gaurav; Kaushik, Anupama; Ghosh, Anup K.

    2011-12-01

    Nanocomposite thin films were prepared with polyurethane as a matrix and organically modified clay as a filler. The interfacial interaction between the exfoliated clay nanoplatelets and the polymeric chains has been investigated by using Atomic Force Microscopy (AFM). The nanoclay platelets show a preferential association with the hard domains of polyurethane matrix on the surface of the thin films. The pendant hydroxyl group on the nanoplatelets attract the isocyanate of the polyisocyanate and a urethane group is formed. This leads to the `clouding' and `entwining' of the nanoplatelets by the hard segmental chains. This is the first visual evidence of nanomaterial filler and polymer matrix interaction and it could open up a spectrum of novel property achievements in nanocomposite thin films. Also the understanding of this interaction can lead to more controlled architecture of nanocomposites.

  16. Multiscale Modeling at Nanointerfaces: Polymer Thin Film Materials Discovery via Thermomechanically Consistent Coarse Graining

    NASA Astrophysics Data System (ADS)

    Hsu, David D.

    Due to high nanointerfacial area to volume ratio, the properties of "nanoconfined" polymer thin films, blends, and composites become highly altered compared to their bulk homopolymer analogues. Understanding the structure-property mechanisms underlying this effect is an active area of research. However, despite extensive work, a fundamental framework for predicting the local and system-averaged thermomechanical properties as a function of configuration and polymer species has yet to be established. Towards bridging this gap, here, we present a novel, systematic coarse-graining (CG) method which is able to capture quantitatively, the thermomechanical properties of real polymer systems in bulk and in nanoconfined geometries. This method, which we call thermomechanically consistent coarse-graining (TCCG), is a two-bead-per-monomer CG hybrid approach through which bonded interactions are optimized to match the atomistic structure via the Iterative Boltzmann Inversion method (IBI), and nonbonded interactions are tuned to macroscopic targets through parametric studies. We validate the TCCG method by systematically developing coarse-grain models for a group of five specialized methacrylate-based polymers including poly(methyl methacrylate) (PMMA). Good correlation with bulk all-atom (AA) simulations and experiments is found for the temperature-dependent glass transition temperature (Tg) Flory-Fox scaling relationships, self-diffusion coefficients of liquid monomers, and modulus of elasticity. We apply this TCCG method also to bulk polystyrene (PS) using a comparable coarse-grain CG bead mapping strategy. The model demonstrates chain stiffness commensurate with experiments, and we utilize a density-correction term to improve the transferability of the elastic modulus over a 500 K range. Additionally, PS and PMMA models capture the unexplained, characteristically dissimilar scaling of Tg with the thickness of free-standing films as seen in experiments. Using vibrational

  17. Langmuir Films of Flexible Polymers Transferred to Aqueous/Liquid Crystal Interfaces Induce Uniform Azimuthal Alignment of the Liquid Crystal

    PubMed Central

    Kinsinger, Michael I.; Buck, Maren E.; Meli, Maria-Victoria; Abbott, Nicholas L.; Lynn, David M.

    2009-01-01

    We reported recently that amphiphilic polymers can be assembled at interfaces created between aqueous phases and thermotropic liquid crystals (LCs) in ways that (i) couple the organization of the polymer to the order of the LC and (ii) respond to changes in the properties of aqueous phases that can be characterized as changes in the optical appearance of the LC. This investigation sought to characterize the behavior of aqueous-LC interfaces decorated with uniaxially compressed thin films of polymers transferred by Langmuir-Schaefer (LS) transfer. Here, we report physicochemical characterization of interfaces created between aqueous phases and the thermotropic LC 4-cyano-4’-pentylbiphenyl (5CB) decorated with Langmuir films of a novel amphiphilic polymer (polymer 1), synthesized by the addition of hydrophobic and hydrophilic side chains to poly(2-vinyl-4,4’-dimethylazlactone). Initial characterization of this system resulted in the unexpected observation of uniform azimuthal alignment of 5CB after LS transfer of the polymer films to aqueous-5CB interfaces. This paper describes characterization of Langmuir films of polymer 1 hosted at aqueous-5CB interfaces as well as the results of our investigations into the origins of the uniform ordering of the LC observed upon LS transfer. Our results, when combined, support the conclusion that uniform azimuthal alignment of 5CB is the result of long-range ordering of polymer chains in the Langmuir films (in a preferred direction orthogonal to the direction of compression) that is generated during uniaxial compression of the films prior to LS transfer. Although past studies of Langmuir films of polymers at aqueous-air interfaces have demonstrated that in-plane alignment of polymer backbones can be induced by uniaxial compression, these past reports have generally made use of polymers with rigid backbones. One important outcome of this current study is thus the observation of anisotropy and long-range order in Langmuir films

  18. Enhanced dielectric performance in polymer composite films with carbon nanotube-reduced graphene oxide hybrid filler.

    PubMed

    Kim, Jin-Young; Kim, TaeYoung; Suk, Ji Won; Chou, Harry; Jang, Ji-Hoon; Lee, Jong Ho; Kholmanov, Iskandar N; Akinwande, Deji; Ruoff, Rodney S

    2014-08-27

    The electrical conductivity and the specific surface area of conductive fillers in conductor-insulator composite films can drastically improve the dielectric performance of those films through changing their polarization density by interfacial polarization. We have made a polymer composite film with a hybrid conductive filler material made of carbon nanotubes grown onto reduced graphene oxide platelets (rG-O/CNT). We report the effect of the rG-O/CNT hybrid filler on the dielectric performance of the composite film. The composite film had a dielectric constant of 32 with a dielectric loss of 0.051 at 0.062 wt% rG-O/CNT filler and 100 Hz, while the neat polymer film gave a dielectric constant of 15 with a dielectric loss of 0.036. This is attributed to the increased electrical conductivity and specific surface area of the rG-O/CNT hybrid filler, which results in an increase in interfacial polarization density between the hybrid filler and the polymer.

  19. Sorting ring polymers by knot type with modulated nanochannels.

    PubMed

    Marenda, Mattia; Orlandini, Enzo; Micheletti, Cristian

    2017-01-25

    In this theoretical study we discuss a novel method for sorting ring polymers according to their topological, knotted state. The proposed approach harnesses the rich dynamical behaviour of polymers confined inside spatially-modulated nanochannels. The longitudinal mobility of the rings is shown to have two key properties that are ideally suited for knot sorting. First, at fixed topology, the mobility has an intriguing oscillatory dependence on chain length. Second, the mobility ranking of different knot types is inverted upon increasing the chain length. We show that this complex interplay of channel geometry, chain length and topology can be rationalised within a simple theoretical framework based on Fick-Jacobs's diffusive theory. The results and the interpretative scheme ought to be useful for designing microfluidic devices with optimal topological sorting capabilities.

  20. Photoinduced bending behavior of cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone.

    PubMed

    Lv, Jiu-an; Wang, Weiru; Xu, Jixiang; Ikeda, Tomiki; Yu, Yanlei

    2014-07-01

    Cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation.

  1. Fabrication of a three-dimensional nanoporous polymer film as a diffuser for microcavity OLEDs

    NASA Astrophysics Data System (ADS)

    Pyo, Beom; Cho, Ye Ram; Suh, Min Chul

    2015-09-01

    We used a nanoporous polymer film prepared by cellulose acetate butyrate with ~40% of optical haze value as a diffuser. It was fabricated by a simple spin-coating process during continuous water mist supply by a humidifier. The pores were created by the elastic bouncing mechanism (rather than the thermocapillary convection mechanism) of the supplied water droplets. The shapes and sizes of the caves formed near the polymer surface are randomly distributed, with a relatively narrow pore size distribution (300-500 nm). Specifically, we focused on controlling the surface morphology to give a three-dimensional (3D) multi-stacked nanocave structure because we had already learnt that two-dimensional nanoporous structures showed serious loss of luminance in the forward direction. Using this approach, we found that the 3D nanoporous polymer film can effectively reduce the viewing angle dependency of strong microcavity OLEDs without any considerable decrease in the total intensity of the out-coupled light. We applied this nanoporous polymer film to microcavity OLEDs to investigate the possibility of using it as a diffuser layer. The resulting nanoporous polymer film effectively reduced the viewing angle dependency of the microcavity OLEDs, although a pixel blurring phenomenon occurred. Despite its negative effects, such as the drop in efficiency in the forward direction and the pixel blurring, the introduction of a nanoporous polymer film as a scattering medium on the back side of the glass substrate eliminated the viewing angle dependency. Thus, this approach is a promising method to overcome the serious drawbacks of microcavity OLEDs.

  2. 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.

  3. Effect of low-molecular-weight beta-cyclodextrin polymer on release of drugs from mucoadhesive buccal film dosage forms.

    PubMed

    Arakawa, Yotaro; Kawakami, Shigeru; Yamashita, Fumiyoshi; Hashida, Mitsuru

    2005-09-01

    We investigated the effect of low-molecular-weight beta-cyclodextrin (beta-CyD) polymer on in vitro release of two drugs with different lipophilicities (i.e., lidocaine and ketoprofen) from mucoadhesive buccal film dosage forms. When beta-CyD polymer was added to hydroxypropylcellulose (HPC) or polyvinylalcohol (PVA) film dosage forms, the release of lidocaine into artificial saliva (pH 5.7) was reduced by 40% of the control. In contrast, the release of ketoprofen from the polymer film was enhanced by addition of beta-CyD polymer to the vehicle. When lidocaine and ketoprofen was incubated with beta-CyD polymer in the artificial saliva, concentration of free lidocaine molecules decreased in a beta-CyD polymer concentration-dependent manner. The association constant with beta-CyD polymer was 6.9+/-0.6 and 520+/-90 M(-1) for lidocaine and ketoprofen, respectively. Retarded release of the hydrophilic lidocaine by beta-CyD polymer might be due to the decrease in thermodynamic activity by inclusion complex formation, whereas enhanced release of the lipophilic ketoprofen by the beta-CyD polymer might be due to prevention of recrystallization occurring after contacting the film with aqueous solution. Thus, effects of low-molecular-weight beta-CyD polymer to the drug release rate from film dosage forms would vary according to the strength of interaction with and the solubility of active ingredient.

  4. Polymer electrolytes with multiple conductive channels prepared from NBR/SBR latex films impregnated with lithium salt and plasticizer

    SciTech Connect

    Matsumoto, Morihiko; Rutt, J.S.; Nishi, Shiro

    1995-09-01

    Polymer electrolytes, composed of a polar polymer acting as a host matrix for lithium-salt solutions, have high ionic conductivity and have been studied for application in advanced electronic devices such as the rechargeable lithium battery. Polymer electrolytes with high ionic conductivity (> 10{sup {minus}3} S/cm) and good tensile strength were prepared by swelling poly(acrylonitrile-co-butadiene) (NBR)/poly(styrene-co-butadiene) (SBR)/LiClO{sub 4} latex films with {gamma}-butyrolactone ({gamma}-BL) or LiClO{sub 4}/{gamma}-BL plasticizer. Before swelling, the LiClO{sub 4} phase is formed at the particle interface. After politicization, two ion-conductive channels are present: the LiClO{sub 4} phase is present at the interface of the latex particles, and the NBR phase is formed from NBR latex particles. These regions are polar and impregnated selectively with polar {gamma}-BL solvent or LiClO{sub 4}/{gamma}-BL solution, building primary and secondary ion-conductive channels, respectively. The SBR phase (formed from SBR latex particles) is nonpolar and not impregnated, providing a mechanically supportive matrix. High ionic conductivity on the order of 10{sup {minus}3} S/cm is achieved when NBR/SBR(50/50)/LiClO{sub 4} latex film was saturated on 0.2 to 0.4M LiClO{sub 4}/{gamma}-BL solutions. Various microscopic and macroscopic analyses suggest that two types of ion-conductive channels exist in the polymer electrolyte film.

  5. A novel nano-bubble inflation method for determining the viscoelastic properties of ultrathin polymer films.

    PubMed

    O'Connell, P A; McKenna, G B

    2008-01-01

    We describe a novel experimental technique for measuring the absolute creep compliance of ultrathin polymer films. The method is based on the classical bubble inflation technique for measuring the biaxial creep compliance of films, reduced in size to measure films with thicknesses down to at least 11.3 nm. The method uses the imaging capabilities of the atomic force microscope (AFM) to determine the time evolution of the geometry of nano-bubbles and thus avoids the problems with data interpretation that can arise due to "contact mechanics" issues when the AFM is used as a direct mechanical testing device.

  6. Preparation of a Thermally Light-Transmittance-Controllable Film from a Coexistent System of Polymer-Dispersed and Polymer-Stabilized Liquid Crystals.

    PubMed

    Guo, Shu-Meng; Liang, Xiao; Zhang, Cui-Hong; Chen, Mei; Shen, Chen; Zhang, Lan-Ying; Yuan, Xiao; He, Bao-Feng; Yang, Huai

    2017-01-25

    Polymer-dispersed liquid crystal (PDLC) and polymer-stabilized liquid crystal (PSLC) systems are the two primary distinct systems in the field of liquid crystal (LC) technology, and they are differentiated by their unique microstructures. Here, we present a novel coexistent system of polymer-dispersed and polymer-stabilized liquid crystals (PD&SLCs), which forms a homeotropically aligned polymer network (HAPN) within the LC droplets after a microphase separation between the LC and polymer matrix and combines the advantages of both the PDLC and PSLC systems. Then, we prepare a novel thermally light-transmittance-controllable (TLTC) film from the PD&SLC system, where the transmittance can be reversibly changed through thermal control from a transparent to a light-scattering state. The film also combines the advantageous features of flexibility and a potential for large-scale manufacturing, and it shows significant promise in future applications from smart windows to temperature sensors.

  7. Robust Polymer Films: Nanoscale Stiffening as a Route to Strong Materials

    DTIC Science & Technology

    2011-10-20

    Thermodynamique et Mécanique," Institut Charles Sadron, Strasbourg, FR, May 2, 2011. **G.B. McKenna, "Rheological Response of Ultrathin Polymer Films...India, Jan. 4-20, 2010. **G.B. McKenna, "Comportement des Matériaux à l’Echelle Nanométrique: Mesures Thermodynamiques et Mécaniques," Michelin

  8. Complex Nanoscale-Ordered Liquid Crystal Polymer Film for High Transmittance Holographic Polarizer.

    PubMed

    Du, Tao; Fan, Fan; Tam, Alwin Ming Wai; Sun, Jiatong; Chigrinov, Vladimir G; Sing Kwok, Hoi

    2015-11-25

    A special design of a complex-ordered liquid crystal polymer film is developed into a holographic polarizer. The holographic polarizer shows over 90% transmittance, which provides a simple solution to make LEDs polarized. Furthermore, the holographic polarizer exhibits intensity and polarization maintenance properties, which could be further developed for photonics applications.

  9. Porous polymer film calcium ion chemical sensor and method of using the same

    DOEpatents

    Porter, M.D.; Chau, L.K.

    1991-02-12

    A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porous polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction. 1 figure.

  10. Porous polymer film calcium ion chemical sensor and method of using the same

    DOEpatents

    Porter, Marc D.; Chau, Lai-Kwan

    1991-02-12

    A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porour polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction.

  11. A study on the microstructural parameters of 550 keV electron irradiated Lexan polymer films

    SciTech Connect

    Hareesh, K.; Pramod, R.; Petwal, V. C.; Dwivedi, Jishnu; Sangappa; Sanjeev, Ganesh

    2012-06-05

    Lexan polymer films irradiated with 550 keV Electron Beam (EB) were characterized using Wide Angle Xray Scattering (WAXS) data to study the microstructural parameters. The crystal imperfection parameters like crystal size , lattice strain (g in %) and enthalpy ({alpha}) have been determined by Line Profile Analysis (LPA) using Fourier method of Warren.

  12. Thermal and mechanical properties of glycerol-based polymer films infused with plant cell wall polysaccharides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(glutaric acid-co-glycerol) films were produced by first synthesizing polymer gels from uncatalyzed polyesterification of glutaric acid to glycerol in toluene. Residual amounts of starting materials in the gel matrices were determined by gas chromatography (GC) to contain 15 percent glycerol and...

  13. Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

    SciTech Connect

    Jorgensen, G.; Gee, R.; DiGrazia, M.

    2010-10-01

    Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

  14. Research on the electronic and optical properties of polymer and other organic molecular thin films

    SciTech Connect

    1997-02-01

    The main goal of the work is to find materials and methods of optimization of organic layered electroluminescent cells and to study such properties of polymers and other organic materials that can be used in various opto-electronic devices. The summary of results obtained during the first year of work is presented. They are: (1) the possibility to produce electroluminescent cells using a vacuum deposition photoresist technology for commercial photoresists has been demonstrated; (2) the idea to replace the polyaryl polymers by other polymers with weaker hole conductivity for optimization of electroluminescent cells with ITO-Al electrodes has been suggested. The goal is to obtain amorphous processable thin films of radiative recombination layers in electroluminescent devices; (3) procedures of preparation of high-quality vacuum-deposited poly (p-phenylene) (PPP) films on various substrates have been developed; (4) it was found for the first time that the fluorescence intensity of PPP films depends on the degree of polymerization; (5) the role of interfaces between organic compounds, on one side, and metals or semiconductors, on the other side, has been studied and quenching of the fluorescence caused by semiconductor layer in thin sandwiches has been observed; (6) studies of the dynamics of photoexcitations revealed the exciton self-trapping in quasi-one-dimensional aggregates; and (7) conditions for preparation of highly crystalline fullerene C{sub 60} films by vacuum deposition have been found. Composites of C{sub 60} with conjugated polymers have been prepared.

  15. Extremely high rate deposition of polymer multilayer optical thin film materials

    SciTech Connect

    Affinito, J.D.

    1993-01-01

    This paper highlights a new technique for extremely high rate deposition of optical dielectric films (vacuum deposition of polymer multilayer thin films). This is a way to produce multilayer optical filters comprised of thousands of layers of either linear or nonlinear optical materials. The technique involves the flash evaporation of an acrylic monomer onto a moving substrate; the monomer is then cured. Acrylic polymers deposited to date are very clear for wavelengths between 0.35 and 2.5 [mu]m; they have extinction coefficients of k[approx]10[sup [minus]7]. Application of electric field during cross linking can polarize (''pole'') the film to greatly enhance the nonlinear optical properties. ''Poling'' films with the polymer multilayer technique offers advantages over conventional approaches, in that the polarization should not decay over time. Battelle's Pacific Northwest Laboratory is well suited for bringing linear and nonlinear polymer multilayer optical filter technology to manufacturing production status for batch and wide area web applications. 10 figs.

  16. Extremely high rate deposition of polymer multilayer optical thin film materials

    SciTech Connect

    Affinito, J.D.

    1993-03-01

    This paper highlights a new technique for extremely high rate deposition of optical dielectric films (vacuum deposition of polymer multilayer thin films). This is a way to produce multilayer optical filters comprised of thousands of layers of either linear or nonlinear optical materials. The technique involves the flash evaporation of an acrylic monomer onto a moving substrate; the monomer is then cured. Acrylic polymers deposited to date are very clear for wavelengths between 0.35 and 2.5 {mu}m; they have extinction coefficients of k{approx}10{sup {minus}7}. Application of electric field during cross linking can polarize (``pole``) the film to greatly enhance the nonlinear optical properties. ``Poling`` films with the polymer multilayer technique offers advantages over conventional approaches, in that the polarization should not decay over time. Battelle`s Pacific Northwest Laboratory is well suited for bringing linear and nonlinear polymer multilayer optical filter technology to manufacturing production status for batch and wide area web applications. 10 figs.

  17. Electrodeposition of nickel oxyhydroxide films through polymer masks

    SciTech Connect

    Yang, M.C.; Lin, C.K.; Su, C.L.

    1995-04-01

    Electrochromic materials have attracted much attention for devices including ``smart windows`` and displays. Nickel oxyhydroxide films were electrodeposited through gelatin masks, whose thicknesses may control the optical transmittances of the deposited electrochromic films. The difference of transmittance, {Delta}T{sub 540}, between bleaching and coloration states at wavelength of 540 nm has a linear relationship with the gelatin mask thickness. {Delta}T{sub 540} increased if nickel oxyhydroxide was prepared in agitated electrolyte. The electrodeposited films, prepared with gelatin masks, may have higher stability. These results showed the feasibility of fabricating an electrochromic device with a controlled image whose contrast and brightness are adjustable with potential or current.

  18. Growth and characterization of polymer thin films grown using molecular layer deposition with heterobifunctional precursors

    NASA Astrophysics Data System (ADS)

    Gibbs, Zachary Michael Conway

    In this work, growth of thin polymer films using molecular layer deposition with heterobifunctional precursors is investigated. Several growth phenomena are observed including: loss or gain of reactive sites as a result of precursor reactivity or vapor pressure; precursor diffusion and reaction within the porous polymer film; and crosslinking. Reactions were investigated using quartz crystal microbalance, Fourier transform infrared spectroscopy, and various ex situ techniques. Reactions involving 4-azidophenylisothiocyanate and 4-aminobenzonitrile were shown to stop growth after only a few cycles which is attributed to a loss in reactive sites which was modeled by an exponentially decaying growth rate. Growth of 4-carboxyphenylisothiocyanate with TMA and water was investigated as well. Active site multiplication as a result of the trifunctionality of the TMA molecule was proposed to explain the significantly higher growth rate for TMA/CI films. TMA/H2O/CI films showed the ability to crosslink through aluminum hydroxyl condensation reactions. Upon increasing the reaction temperature, reactant diffusion was observed in the form of mass removal upon TMA exposure. This same phenomena is thought to be occurring in films grown using Diels-Alder reactions in the third section of this thesis. These films showed a strong growth rate dependence upon reactant purge time and growth temperature. FTIR seems to weakly support Diels-Alder reaction, but it appears that the primary film growth mechanism is through CVD-like diffusion and condensation reactions.

  19. The role of polymer films on the oxidation of magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Letti, C. J.; Paterno, L. G.; Pereira-da-Silva, M. A.; Morais, P. C.; Soler, M. A. G.

    2017-02-01

    A detailed investigation about the role of polymer films on the oxidation process of magnetite nanoparticles (∼7 nm diameter), under laser irradiation is performed employing micro Raman spectroscopy. To support this investigation, Fe3O4-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe3O4-np/PSS)n with n=2,3,5,7,10 and 25 bilayers are employed as a model system to study the oxidation process under laser irradiation. Raman data are further processed by principal component analysis. Our findings suggest that PSS protects Fe3O4-np from oxidation when compared to powder samples, even for the sample with the greater number of bilayers. Further, the oxidation of magnetite to maghemite occurs preferably for thinner films up to 7 bilayers, while the onset for the formation of the hematite phase depends on the laser intensity for thicker films. Water takes part on the oxidation processes of magnetite, the oxidation/phase transformation of Fe3O4-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe3O4-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite.

  20. Combinatorial Synthesis of and high-throughput protein release from polymer film and nanoparticle libraries.

    PubMed

    Petersen, Latrisha K; Chavez-Santoscoy, Ana V; Narasimhan, Balaji

    2012-09-06

    Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with conventional one-sample-at-a-time synthesis techniques, a more recent high-throughput approach has been developed enabling the synthesis and testing of large libraries of polyanhydrides(1). This will facilitate more efficient optimization and design process of these biomaterials for drug and vaccine delivery applications. The method in this work describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries. In this robotically operated method (Figure 1), linear actuators and syringe pumps are controlled by LabVIEW, which enables a hands-free automated protocol, eliminating user error. Furthermore, this method enables the rapid fabrication of micro-scale polymer libraries, reducing the batch size while resulting in the creation of multivariant polymer systems. This combinatorial approach to polymer synthesis facilitates the synthesis of up to 15 different polymers in an equivalent amount of time it would take to synthesize one polymer conventionally. In addition, the combinatorial polymer library can be fabricated into blank or protein-loaded geometries including films or nanoparticles upon dissolution of the polymer library in a solvent and precipitation into a non-solvent (for nanoparticles) or by vacuum drying (for films). Upon loading a fluorochrome-conjugated protein into the polymer libraries, protein release kinetics can be assessed at high-throughput using a fluorescence-based detection method (Figures 2 and 3) as described previously(1). This combinatorial platform has been validated with conventional methods(2) and the polyanhydride film and nanoparticle libraries have been characterized with (1)H NMR and FTIR. The libraries have been screened for protein release kinetics, stability and

  1. Making Glasses Conduct: Electrochemical Doping of Redox-Active Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Boudouris, Bryan

    Optoelectronically-active macromolecules have been established as promising materials in myriad organic electronic applications (e.g., organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices). To date, however, the majority of the work surrounding these materials has focused on materials with a great deal of conjugation along their macromolecular backbones and with varying degrees of crystalline structure. Here, we describe an emerging class of macromolecular charge conductors, radical polymers, that: (1) do not contain conjugation and (2) are completely amorphous glasses. Radical polymers contain non-conjugated macromolecular backbones and stable radical sites along the side chains of the electronically-active materials. In contrast to conjugated polymer systems, these materials conduct charge in the solid state through oxidation-reduction (redox) reactions along these pendant groups. Specifically, we demonstrate that controlling the chemical functionality of the pendant groups and the molecular mobility of the macromolecular backbones significantly impacts the charge transport ability of the pristine (i.e., not doped) radical polymers species. Through proper control of these crucial parameters, we show that radical polymers can have electrical conductivity and charge mobility values on par with commonly-used conjugated polymers. Importantly, we also highlight the ability to dope radical polymers with redox-active small molecule species. This doping, in turn, increases the electrical conductivity of the glassy radical polymer thin films in a manner akin to what is observed in traditional conjugated polymer systems. In this way, we establish a means by which to fabricate optically-transparent and colorless thin film glasses capable of conducting charge in a rather rapid manner. We anticipate that these fundamental insights will prove crucial in developing new transparent conducting layers for future electronic applications.

  2. Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy

    SciTech Connect

    Himmelhuber, R. Mehravar, S. S.; Herrera, O. D.; Demir, V.; Kieu, K.; Norwood, R. A.; Peyghambarian, N.; Luo, J.; Jen, A. K.-Y.

    2014-04-21

    We imaged coplanar poled electro optic (EO) polymer films on transparent substrates with a multiple-photon microscope in reflection and correlated the second-harmonic light intensity with the results of Pockels coefficient (r{sub 33}) measurements. This allowed us to make quantitative measurements of poled polymer films on non-transparent substrates like silicon, which are not accessible with traditional Pockels coefficient measurement techniques. Phase modulators consisting of silicon waveguide devices with EO polymer claddings with a known Pockels coefficient (from V{sub π} measurements) were used to validate the correlation between the second-harmonic signal and r{sub 33}. This also allowed us to locally map the r{sub 33} coefficient in the poled area.

  3. Dynamics of photoinduced processes in liquid-crystal polymer films containing azo compounds

    SciTech Connect

    Simonov, A N; Larichev, A V

    1999-07-31

    The photoinduced processes in azo-compound-containing side-chain polymer films with liquid-crystal properties are examined theoretically. A model is proposed whereby it is possible to consider the dynamics of the optical response of a medium taking into account the anisotropic saturation in the angular distribution of the azo-dye isomers as well as the intermolecular interaction. The influence of the liquid-crystal ordering in the polymer is taken into account by introducing a phenomenological mean-field factor. Analytical solutions describing changes in the optical properties of a polymer film during the initial illumination stages are in good agreement with experimental data. (this issue is dedicated to the memory of s a akhmanov)

  4. Impact of systematic chain architecture changes on the glass transition and modulus of thin polymer films

    NASA Astrophysics Data System (ADS)

    Vogt, Bryan; Torres, Jessica; Stafford, Christopher; Register, Richard; Uhrig, David

    2012-02-01

    We will discuss two systems that significantly impact the thin film behavior with minor changes in chemistry and chain architecture. First, two polymers based on 5-(2-phenylethylnorbornene) are examined. Depending on the polymerization route chosen, the resulting polymer backbone is comprised of either bicyclic (norbornyl) units, which leads to a relatively rigid polymer with a high bulk Tg, or monocyclic (cyclopentyl) units, which leads to a more flexible structure with a lower bulk Tg. The modulus and Tg of the rigid bicyclic polymer is thickness independent down to <10 nm, whereas the modulus of the more flexible monocyclic polymer decreases with decreasing thickness. By hydrogenation of the pendant phenyl ring to the cyclohexyl counterpart, we illustrate that minor changes in the relative flexibility of the side chain do not impact the observed thin film behavior. Second, a series of polystyrene with controlled branching including linear, comb, 6-arm star and centipede. Based upon the molecular mass of the arms, the comb polymer has a significantly larger persistence length and interestingly exhibits only a modest decrease in Tg (9 K) at 5 nm, while the moduli is thickness independent.

  5. 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.

  6. The role of interdiffusion in the film formation of polymer latices

    SciTech Connect

    Zosel, A.; Ley, G.

    1995-12-31

    The mechanical strength of films from polymer lattices develops by the interdiffusion of chain segments and the formation of entanglements across particle boundaries during film formation. Measurements of the fracture energy of poly-n-butylmethacrylate films, tempered above the glass transition temperature for different times, show a transition from brittle to tough (yielding) behaviour with a strong increase of the fracture energy at short temper times, which is followed by an increase of the fracture energy proportional to the square root of the temper time until a constant fracture energy is reached after long times. The film strength is correlated to the interdiffusion length determined by small angle neutron scattering of deuterated films. The formation of interparticular entanglements is hindered in lattices with crosslinked particles, as has been studied with a series of lattices, crosslinked with various amounts of a bifunctional monomer.

  7. Topography-guided buckling of swollen polymer bilayer films into three-dimensional structures.

    PubMed

    Jeong, Joonwoo; Cho, Yigil; Lee, Su Yeon; Gong, Xingting; Kamien, Randall D; Yang, Shu; Yodh, A G

    2017-02-07

    Thin films that exhibit spatially heterogeneous swelling often buckle into the third dimension to minimize stress. These effects, in turn, offer a promising strategy to fabricate complex three-dimensional structures from two-dimensional sheets. Here we employ surface topography as a new means to guide buckling of swollen polymer bilayer films and thereby control the morphology of resulting three-dimensional objects. Topographic patterns are created on poly(dimethylsiloxane) (PDMS) films selectively coated with a thin layer of non-swelling parylene on different sides of the patterned films. After swelling in an organic solvent, various structures are formed, including half-pipes, helical tubules, and ribbons. We demonstrate these effects and introduce a simple geometric model that qualitatively captures the relationship between surface topography and the resulting swollen film morphologies. The model's limitations are also examined.

  8. Layer-by-layer assembly of ferrocene-modified linear polyethylenimine redox polymer films.

    PubMed

    DeLuca, Jared L; Hickey, David P; Bamper, Daniel A; Glatzhofer, Daniel T; Johnson, Matthew B; Schmidtke, David W

    2013-07-22

    Herein, both electrostatic and covalent layer-by-layer assembly were used for the construction of multicomposite thin films using a ferrocene-modified linear poly(ethylenimine) redox polymer (Fc-C6-LPEI) as the cationic polyelectrolye, and poly(acrylic acid) (PAA), poly(glutamic acid) (PGA), or glucose oxidase (GOX) as the negative polyelectrolyte. The assembly of the multilayer films was characterized by cyclic voltammetry (CV), UV/Vis spectroscopy, and ellipsometry with the enzymatic response of the films containing GOX being characterized via constant potential amperometry. CV measurements suggested that the successful buildup of multilayer films was dependent upon the nature of the anionic polyelectrolyte used. Electrostatic assembly of films composed of Fc-C6-LPEI and either PAA or PGA produced large oxidation peak current densities of 630 and 670 μA cm(-2), respectively, during cyclic voltammetry. Increased measured absorbance by UV/Vis spectroscopy and increased measured film thicknesses (400-600 nm) by ellipsometry provided additional evidence of successful film formation. In contrast, the films incorporating GOX that were electrostatically assembled surprisingly produced significantly lower electrochemical responses (12 μA cm(-2)), low absorbance values, and reduced film thicknesses (~15 nm), and glucose electro-oxidation current densities less than 1 μA cm(-2), which all suggested unstable or minimal film formation. Subsequently, we developed a covalent layer-by-layer approach to fabricate films of Fc-C6-LPEI/GOX by covalently linking the amine groups of Fc-C6-LPEI to the aldehyde groups of periodate-oxidized glucose oxidase. Covalent assembly of the Fc-C6-LPEI/GOX films produced oxidation peak current densities during cyclic voltammetry of 40 μA cm(-2) and glucose electro-oxidation current densities of 220 μA cm(-2). These films also showed an increase in their thicknesses (~140 nm) relative to the electrostatic GOX films. For the films containing

  9. Gate-voltage-dependent charge transport in multi-dispersed polymer thin films

    NASA Astrophysics Data System (ADS)

    Zhou, Ling; Bu, Laju; Li, Dongfan; Lu, Guanghao

    2017-02-01

    In semiconductor polymers, charge transport usually occurs via hopping between localized states, which are generally multi-dispersed due to multi-dispersed chemical structures, crystallinities, and phase segregations. We report a combined modeling and experimental study to investigate gate-voltage-dependent charge transport in field-effect transistors based on multi-dispersed polymers including semiconductor:semiconductor and semiconductor:insulator blends. Film-depth-dependent charge accumulation and transport are correlated with vertical composition profiles and film-depth-dependent energetic distribution of localized states. Even low gate-voltage could accumulate charges in any depth of the films, greatly increasing charge density in some (sub-) components for effective charge transport. Therefore, neither overall high crystallinity nor molecular ordering near the semiconductor-dielectric interface is necessarily required for high field-effect mobility (μFET). This study not only proposes a model for high effective μFET recently reported in some nearly amorphous polymer films and the "bislope feature" in their transfer characteristics but also helps improve transistor performances and exploit transistor operations via manipulating charge distribution in multi-dispersed films.

  10. Exploring the existence of two Tgs in thin, supported polymer films

    NASA Astrophysics Data System (ADS)

    Chen, Eric; Glor, Ethan; Angrand, Gabriel; Fakhraai, Zahra; Fakhraai Group Team

    Ellipsometry has commonly been used to characterize the glass transition temperature (Tg) and other properties of nanoscale thin films. In some ultra-thin films the glass transition broadens and even becomes two distinct transitions, as previously observed in free-standing polystyrene, thin films. However, for most polymers, the second, lower Tg is located below the condensation temperature of water, generating large errors in determining the lower Tg, which is associated with the layer close to the free interface. Here we designed a vacuum stage with a base pressure of <1E-4 torr, equipped with a Linkam temperature stage with a temperature range of 153 K-873 K to study the properties of thin polymer films, supported on a substrate, in a broad temperature range and explore the existence of two Tgs in these systems. The stage was machined from aluminum and used infrasil quartz windows to allow the transmission of polarized light without distortion. The vacuum allows for accurate ellipsometry measurements of the properties of thin polymer films, such as expansion coefficient and Tg, at temperatures well below room temperature, without artifacts due to water condensation. Mrsec (NSF-DMR-11- 20901).

  11. Roll-to-roll embossing of optical linear Fresnel lens polymer film for solar concentration.

    PubMed

    Zhang, XinQuan; Liu, Kui; Shan, Xuechuan; Liu, Yuchan

    2014-12-15

    Roll-to-roll manufacturing has been proven to be a high-throughput and low-cost technology for continuous fabrication of functional optical polymer films. In this paper, we have firstly studied a complete manufacturing cycle of linear Fresnel lens polymer film for solar concentration in the aspects of ultra-precision diamond machining of metal roller mold, roll-to-roll embossing, and measurement on film profile and functionality. A metal roller mold patterned with linear Fresnel lenses is obtained using single point diamond turning technique. The roller mold is installed onto a self-developed roll-to-roll UV embossing system to realize continuous manufacturing of linear Fresnel lens film. Profile measurement of the machined roller mold and the embossed polymer film, which is conducted using a stylus profilometer, shows good agreement between measured facet angles with designed ones. Functionality test is conducted on a solar simulation system with a reference solar cell, and results show that strong light concentration is realized.

  12. An Examination of Radiation Induced Tensile Failure of Stressed and Unstressed Polymer Films Flown on MISSE-6

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K.; Sechkar, Edward A.

    2012-01-01

    Thin film polymers are used in many spacecraft applications for thermal control (multilayer insulation and sunshields), as lightweight structural members (solar array blankets, inflatable/deployable structures) and have been proposed for propulsion (solar sails). Polymers in these applications are often under a tensile load and are directly exposed to the space environment, therefore it is important to understand the effect of stress in combination with the environment on the durability of these polymer films. The purpose of the Polymer Film Tensile Experiment, flown as part of Materials International Space Station Experiment 6 (MISSE 6), was to expose a variety of polymer films to the low Earth orbital environment under both relaxed and tension conditions. This paper describes the results of post flight tensile testing of these samples.

  13. Resonant Infrared Matrix Assisted Pulsed Laser Deposition of Polymers: Improving the Morphology of As-Deposited Films

    NASA Astrophysics Data System (ADS)

    Bubb, Daniel; Papantonakis, Michael; Collins, Brian; Brookes, Elijah; Wood, Joshua; Gurudas, Ullas

    2008-03-01

    Resonant infrared matrix assisted pulsed laser deposition has been used to deposit thin films of PMMA, a widely used industrial polymer. This technique is similar to conventional pulsed laser deposition, except that the polymer to be deposited is dissolved in a solvent and the solution is frozen before ablation in a vacuum chamber. The laser wavelength is absorbed by a vibrational band in the frozen matrix. The polymer lands on the substrate to form a film, while the solvent is pumped away. Our preliminary results show that the surface roughness of the as-deposited films depends strongly on the differential solubility radius, as defined by Hansen solubility parameters of the solvent and the solubility radius of the polymer. Our results will be compared with computational and experimental studies of the same polymer using a KrF (248 nm) laser. The ejection mechanism will be discussed as well as the implications of these results for the deposition of smooth high quality films.

  14. Electrochemical co-deposition of conductive polymer-silica hybrid thin films.

    PubMed

    Raveh, Moran; Liu, Liang; Mandler, Daniel

    2013-07-14

    Conductive polymers, such as polypyrrole (ppy), have been the subject of numerous studies due to their promising applications in organic solar cells, flexible electronics, electrochromic devices, super capacitors, etc. Yet, their application is still limited as a result of poor processability. Silica has been reported to improve the mechanical strength and adhesion of conductive polymer films. In this work, we propose a controllable electrochemical approach for preparing ppy-silica hybrid thin films from a solution containing both pyrrole and silane monomers. It is known that pyrrole can be electropolymerised using anodic potentials, while silica can be electrodeposited under cathodic potentials. Thus, we studied the formation of ppy-silica hybrid thin films on a stainless steel surface by applying alternating potentials, i.e. cathodic followed by anodic pulses (denoted C + A) or anodic followed by cathodic pulses (denoted A + C). We show that by controlling the deposition potential and time for the cathodic and anodic pulses, the film thickness and composition can be manipulated well as analysed using profilometry and EDX. The element depth profile of the films was characterized using secondary ion mass spectroscopy (SIMS). In essence, for the C + A process, pyrrole diffuses through the cathodically electrodeposited wet silica gel layer and undergoes anodic polymerisation on the substrate, while for the A + C process, silane can be electrodeposited both on top of the anodically electrodeposited conductive ppy films as well as on the stainless steel through the pinholes in the ppy film. This offers a simple approach for tuning the structure of conductive polymer-sol-gel composite films.

  15. New N-Type Polymers for Organic Photovoltaics: Cooperative Research and Development Final Report, CRADA Number CRD-06-177

    SciTech Connect

    Olson, D.

    2014-08-01

    This CRADA will develop improved thin film organic solar cells using a new n-type semiconducting polymer. High efficiency photovoltaics (PVs) based on inorganic semiconductors have good efficiencies (up to 30%) but are extremely expensive to manufacture. Organic PV technology has the potential to overcome this problem through the use of high-throughput production methods like reel-to-reel printing on flexible substrates. Unfortunately, today's best organic PVs have only a few percent efficiency, a number that is insufficient for virtually all commercial applications. The limited choice of stable n-type (acceptor) organic semiconductor materials is one of the key factors that prevent the further improvement of organic PVs. TDA Research, Inc. (TDA) previously developed a new class of electron-deficient (n-type) conjugated polymers for use in organic light emitting diodes (OLEDs). During this project TDA in collaboration with the National Renewable Energy Laboratory (NREL) will incorporate these electron-deficient polymers into organic photovoltaics and investigate their performance. TDA Research, Inc. (TDA) is developing new materials and polymers to improve the performance of organic solar cells. Materials being developed at TDA include spin coated transparent conductors, charge injection layers, fullerene derivatives, electron-deficient polymers, and three-phase (fullerene/polythiophene/dye) active layer inks.

  16. Highly efficient Cu(In,Ga)Se2 solar cells grown on flexible polymer films.

    PubMed

    Chirilă, Adrian; Buecheler, Stephan; Pianezzi, Fabian; Bloesch, Patrick; Gretener, Christina; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Perrenoud, Julian; Seyrling, Sieghard; Verma, Rajneesh; Nishiwaki, Shiro; Romanyuk, Yaroslav E; Bilger, Gerhard; Tiwari, Ayodhya N

    2011-09-18

    Solar cells based on polycrystalline Cu(In,Ga)Se(2) absorber layers have yielded the highest conversion efficiency among all thin-film technologies, and the use of flexible polymer films as substrates offers several advantages in lowering manufacturing costs. However, given that conversion efficiency is crucial for cost-competitiveness, it is necessary to develop devices on flexible substrates that perform as well as those obtained on rigid substrates. Such comparable performance has not previously been achieved, primarily because polymer films require much lower substrate temperatures during absorber deposition, generally resulting in much lower efficiencies. Here we identify a strong composition gradient in the absorber layer as the main reason for inferior performance and show that, by adjusting it appropriately, very high efficiencies can be obtained. This implies that future manufacturing of highly efficient flexible solar cells could lower the cost of solar electricity and thus become a significant branch of the photovoltaic industry.

  17. Closed-form Maker fringe formulas for poled polymer thin films in multilayer structures.

    PubMed

    Park, Dong Hun; Herman, Warren N

    2012-01-02

    We report new closed-form expressions for Maker fringes of anisotropic and absorbing poled polymer thin films in multilayer structures that include back reflections of both fundamental and second-harmonic waves. The expressions, based on boundary conditions at each interface, can be applied to multilayer structures containing a buffer and a transparent conducting oxide layer, which might enhance multiple reflections of fundamental and second-harmonic waves inside a nonlinear thin film layer. This formulation facilitates Maker fringe analysis for a sample containing additional multilayer structures on either side of a poled polymer thin film. Experimental data and numerical simulations are given to indicate the importance of inclusion of such a reflective layer in analyses for reliable characterization of second-harmonic tensor elements.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. Current-dependent anisotropic conductivity of locally assembled silver nanoparticles in hybrid polymer films.

    PubMed

    Goel, Pooja; Vinokur, Rostislav; Weichold, Oliver

    2010-12-15

    The electrical behaviour of hybrid poly(ethylene terephthalate) films containing localised, percolating networks of silver nanoparticles separated by pure polymer is studied. The films resemble an array of parallel wires in the submicron range and, thus, exhibit anisotropic conductivity. In the high-conductivity direction at low amplitudes, the films show Ohmic behaviour, while at moderate voltage, non-linearity and a decreasing resistance is observed. The samples were found to heat up during the measurements and the deviation from Ohm's law coincides with the Tg of the polymer. Microstructural analysis of the samples revealed an irreversible agglomeration of the particles at moderate voltages leading to the formation of filaments with higher metallic character than the random particle network.

  20. 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.

  1. Measuring Exciton Migration in Conjugated Polymer Films with Ultrafast Time Resolved Stimulated Emission Depletion Microscopy

    NASA Astrophysics Data System (ADS)

    Penwell, Samuel

    Conjugated polymers are highly tunable organic semiconductors, which can be solution processed to form thin films, making them prime candidates for organic photovoltaic devices. One of the most important parameters in a conjugated polymer solar cell is the exciton diffusion length, which depends on intermolecular couplings, and is typically on the order of 10 nm. This mean exciton migration can vary dramatically between films and within a single film due to heterogeneities in morphology on length scales of 10's to 100's nm. To study the variability of exciton diffusion and morphology within individual conjugated polymer films, we are adapting stimulated emission depletion (STED) microscopy. STED is typically used in biology with sparse well-engineered fluorescent labels or on NV-centers in diamond. I will, however, describe how we have demonstrated the extension of STED to conjugated polymer films and nanoparticles of MEH-PPV and CN-PPV, despite the presence of two photon absorption, by taking care to first understand the material's photophysical properties. We then further adapt this approach, by introducing a second ultrafast STED pulse at a variable delay. Excitons that migrate away from the initial subdiffraction excitation volume during the ps-ns time delay, are preferentially quenched by the second STED pulse, while those that remain in the initial volume survive. The resulting effect of the second STED pulse is modulated by the degree of migration over the ultrafast time delay, thus providing a new method to study exciton migration. Since this technique utilizes subdiffraction optical excitation and detection volumes with ultrafast time resolution, it provides a means of spatially and temporally resolving measurements of exciton migration on the native length and time scales. In this way, we will obtain a spatiotemporal map of exciton distributions and migration that will help to correlate the energetic landscape to film morphology at the nanoscale.

  2. Spectroelectrochemical Sensors: New Polymer Films for Improved Sensitivity

    SciTech Connect

    Morris, Laura K.; Seliskar, Carl J.; Bryan, Samuel A.; Heineman, William R.

    2014-10-31

    The selectivity of an optical sensor can be improved by combining optical detection with electrochemical oxidation or reduction of the target analyte to change its spectral properties. The changing signal can distinguish the analyte from interferences with similar spectral properties that would otherwise interfere. The analyte is detected by measuring the intensity of the electrochemically modulated signal. In one form this spectroelectrochemical sensor consists of an optically transparent electrode (OTE) coated with a film that preconcentrates the target analyte. The OTE functions as an optical waveguide for attenuated total reflectance (ATR) spectroscopy, which detects the analyte by absorption. Sensitivity relies in part on a large change in molar absorptivity between the two oxidation states used for electrochemical modulation of the optical signal. A critical part of the sensor is the ion selective film. It should preconcentrate the analyte and exclude some interferences. At the same time the film must not interfere with the electrochemistry or the optical detection. Therefore, since the debut of the sensor’s concept one major focus of our group has been developing appropriate films for different analytes. Here we report the development of a series of quaternized poly(vinylpyridine)-co-styrene (QPVP-co-S) anion exchange films for use in spectroelectrochemical sensors to enable sensitive detection of target anionic analytes in complex samples. The films were either 10% or 20% styrene and were prepared with varying degrees of quaternized pyridine groups, up to 70%. Films were characterized with respect to thickness with spectroscopic ellipsometry, degree of quaternization with FTIR, and electrochemically and spectroelectrochemically using the anions ferrocyanide and pertechnetate.

  3. Spectral studies of Donepezil release from streched PVA polymer films

    NASA Astrophysics Data System (ADS)

    Nechifor, Cristina-Delia; Zelinschi, Carmen-Beatrice; Stoica, Iuliana; Closca, Valentina; Dorohoi, Dana-Ortansa

    2013-07-01

    The focus of this research is to obtain poly vinyl alcohol (PVA) polymer foils containing Donepezil in different concentration, in order to be used in controlled drug release as a palliative treatment of mild to moderate Alzheimer's disease. The influence of polymeric foil stretching degree on drug release was analyzed using spectral measurements.

  4. Morphology-dependent optical anisotropies in the n -type polymer P(NDI2OD-T2)

    NASA Astrophysics Data System (ADS)

    Brown, Steven J.; Schlitz, Ruth A.; Chabinyc, Michael L.; Schuller, Jon A.

    2016-10-01

    Organic semiconductors tend to self-assemble into highly ordered and oriented morphologies with anisotropic optical properties. Studying these optical anisotropies provides insight into processing-dependent structural properties and informs the photonic design of organic photovoltaic and light-emitting devices. Here we measure the anisotropic optical properties of spin-cast films of the n -type polymer P(NDI2OD-T2) using momentum-resolved absorption and emission spectroscopies. We quantify differences in the optical anisotropies of films deposited with distinct face-on and edge-on morphologies. In particular, we infer a substantially larger out-of-plane tilt angle of the optical transition dipole moment in high temperature annealed, edge-on films. Measurements of spectral differences between in-plane and out-of-plane dipoles, further indicate regions of disordered polymers in low temperature annealed face-on films that are otherwise obscured in traditional x-ray and optical characterization techniques. The methods and analysis developed in this work provide a way to identify and quantify subtle optical and structural anisotropies in organic semiconductors that are important for understanding and designing highly efficient thin film devices.

  5. Radiochromic film dosimetry: considerations on precision and accuracy for EBT2 and EBT3 type films.

    PubMed

    Dreindl, Ralf; Georg, Dietmar; Stock, Markus

    2014-05-01

    Gafchromic® EBT2 film is a widely used dosimetric tool for quality assurance in radiation therapy. In 2012 EBT3 was presented as a replacement for EBT2 films. The symmetric structure of EBT3 films to reduce face-up/down dependency as well as the inclusion of a matte film surface to frustrate Newton Ring artifacts present the most prominent improvements of EBT3 films. The aim of this study was to investigate the characteristics of EBT3 films, to benchmark the films against the known EBT2-features and to evaluate the dosimetric behavior over a time period greater than 6 months. All films were irradiated to clinical photon beams (6 MV, 10 MV and 18 MV) on an Elekta Synergy Linac equipped with a Beam Modulator MLC in solid water phantom slabs. Film digitalization was done with a flatbed transparency scanner (Type Epson Expression 1680 Pro). MATLAB® was used for further statistical calculations and image processing. The investigations on post-irradiation darkening, film orientation, film uniformity and energy dependency resulted in negligible differences between EBT2 and EBT3 film. A minimal improvement in face-up/down dependence was found for EBT3. The matte film surface of EBT3 films turned out to be a practical feature as Newton rings could be eliminated completely. Considering long-term behavior (> 6 months) a shift of the calibration curve for EBT2 and EBT3 films due to changes in the dynamic response of the active component was observed. In conclusion, the new EBT3 film yields comparable results to its predecessor EBT2. The general advantages of radiochromic film dosimeters are completed by high film homogeneity, low energy dependence for the observed energy range and a minimized face-up/down dependence. EBT2 dosimetry-protocols can also be used for EBT3 films, but the inclusion of periodical recalibration-interval (e.g. once a quarter) is recommended for protocols of both film generations.

  6. Elastic properties of protein functionalized nanoporous polymer films

    DOE PAGES

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that proteinmore » functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.« less

  7. Elastic properties of protein functionalized nanoporous polymer films

    SciTech Connect

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that protein functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.

  8. Molecular interactions between proteins and synthetic membrane polymer films

    SciTech Connect

    Pincet, F.; Perez, E.; Belfort, G.

    1995-04-01

    To help understand the effects of protein adsorption on membrane filtration performance, we have measured the molecular interactions between cellulose acetate films and two proteins with different properties (ribonuclease A and human serum albumin) with a surface force apparatus. Comparison of forces between two protein layers with those between a protein layer and a cellulose acetate (CA) film shows that, at high pH, both proteins retained their native conformation on interacting with the CA film while at the isoelectric point (pI) or below the tertiary structure of proteins was disturbed. These measurements provide the first molecular evidence that disruption of protein tertiary structure could be responsible for the reduced permeation flows observed during membrane filtration of protein solutions and suggest that operating at high pH values away from the pI of proteins will reduce such fouling. 60 refs., 9 figs., 5 tabs.

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

    PubMed Central

    2011-01-01

    The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ. PMID:21711747

  10. Humidity versus photo-stability of metal halide perovskite films in a polymer matrix.

    PubMed

    Manshor, Nurul Ain; Wali, Qamar; Wong, Ka Kan; Muzakir, Saifful Kamaluddin; Fakharuddin, Azhar; Schmidt-Mende, Lukas; Jose, Rajan

    2016-08-21

    Despite the high efficiency of over 21% reported for emerging thin film perovskite solar cells, one of the key issues prior to their commercial deployment is to attain their long term stability under ambient and outdoor conditions. The instability in perovskite is widely conceived to be humidity induced due to the water solubility of its initial precursors, which leads to decomposition of the perovskite crystal structure; however, we note that humidity alone is not the major degradation factor and it is rather the photon dose in combination with humidity exposure that triggers the instability. In our experiment, which is designed to decouple the effect of humidity and light on perovskite degradation, we investigate the shelf-lifetime of CH3NH3PbI3 films in the dark and under illumination under high humidity conditions (Rel. H. > 70%). We note minor degradation in perovskite films stored in a humid dark environment whereas upon exposure to light, the films undergo drastic degradation, primarily owing to the reactive TiO2/perovskite interface and also the surface defects of TiO2. To enhance its air-stability, we incorporate CH3NH3PbI3 perovskite in a polymer (poly-vinylpyrrolidone, PVP) matrix which retained its optical and structural characteristics in the dark for ∼2000 h and ∼800 h in room light soaking, significantly higher than a pristine perovskite film, which degraded completely in 600 h in the dark and in less than 100 h when exposed to light. We attribute the superior stability of PVP incorporated perovskite films to the improved structural stability of CH3NH3PbI3 and also to the improved TiO2/perovskite interface upon incorporating a polymer matrix. Charge injection from the polymer embedded perovskite films has also been confirmed by fabricating solar cells using them, thereby providing a promising future research pathway for stable and efficient perovskite solar cells.

  11. Electrically Conducting Polymer-Copper Sulphide Composite Films, Preparation by Treatment of Polymer-Copper (2) Acetate Composites with Hydrogen Sulfide

    NASA Technical Reports Server (NTRS)

    Yamamoto, Takakazu; Kamigaki, Takahira; Kubota, Etsuo

    1988-01-01

    Polymer copper sulfide composite films were prepared by treatment of polymer poly(vinyl chloride), poly(acrylonitrile), copolymer of vinyl chloride and vinyl acetate (90:10), and ABS resin copper (2) acetate composites with hydrogen sulfide. The films showed electrical conductivity higher than 0.015 S/cm when they contained more than 20 wt percent of copper sulfide. A poly(acrylonitrile)-copper sulfide composite film containing 40 to 50 wt percent of copper sulfide showed electrical conductivity of 10 to 150.0 S/cm and had relatively high mechanical strength to be used in practical purposes.

  12. Polymer Stress-Gradient Induced Migration in Thin Film Flow Over Topography

    NASA Astrophysics Data System (ADS)

    Tsouka, Sophia; Dimakopoulos, Yiannis; Tsamopoulos, John

    2014-11-01

    We consider the 2D, steady film flow of a dilute polymer solution over a periodic topography. We examine how the distribution of polymer in the planarization of topographical features is affected by flow intensity and physical properties. The thermodynamically acceptable, Mavrantzas-Beris two-fluid Hamiltonian model is used for polymer migration. The resulting system of differential equations is solved via the mixed FE method combined with an elliptic grid generation scheme. We present numerical results for polymer concentration, stress, velocity and flux of components as a function of the non-dimensional parameters of the problem (Deborah, Peclet, Reynolds and Capillary numbers, ratio of solvent viscosity to total liquid viscosity and geometric features of the topography). Polymer migration to the free surface is enhanced when the cavity gets steeper and deeper. This increases the spatial extent of the polymer depletion layer and induces strong banding in the stresses away from the substrate wall, especially in low polymer concentration. Macromolecules with longer relaxation times are predicted to migrate towards the free surface more easily, while high surface tension combined with a certain range of Reynolds numbers affects the free surface deformations. Work supported by the General Secretariat of Research & Technology of Greece through the program ``Excellence'' (Grant No. 1918) in the framework ``Education and Lifelong Learning'' co-funded by the ESF.

  13. Reactive thin polymer films as platforms for the immobilization of biomolecules.

    PubMed

    Feng, Chuan Liang; Zhang, Zhihong; Förch, Renate; Knoll, Wolfgang; Vancso, G Julius; Schönherr, Holger

    2005-01-01

    Spin-coated thin films of poly(N-hydroxysuccinimidyl methacrylate) (PNHSMA) on oxidized silicon and gold surfaces were investigated as reactive layers for obtaining platforms for biomolecule immobilization with high molecular loading. The surface reactivity of PNHSMA films in coupling reactions with various primary amines, including amine-terminated poly(ethylene glycol) (PEG-NH2) and fluoresceinamine, was determined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence microscopy, and ellipsometry measurements, respectively. The rate constants of PEG-NH2 attachment on the PNHSMA films were found to be significantly increased compared to the coupling on self-assembled monolayers (SAMs) of 11,11'-dithiobis(N-hydroxysuccinimidylundecanoate) (NHS-C10) on gold under the same conditions. More significantly, the PEG loading observed was about 3 times higher for the polymer thin films. These data indicate that the coupling reactions are not limited to the very surface of the polymer films, but proceed into the near-surface regions of the films. PNHSMA films were shown to be stable in contact with aqueous buffer; the swelling analysis, as performed by atomic force microscopy (AFM), indicated a film thickness independent swelling of approximately 2 nm. An increased loading was also observed by surface plasmon resonance for the covalent immobilization of amino-functionalized probe DNA. Hybridization of fluorescently labeled target DNA was successfully detected by fluorescence microscopy and surface plasmon resonance enhanced fluorescence spectroscopy (SPFS), thereby demonstrating that thin films of PNHSMA comprise an attractive and simple platform for the immobilization of biomolecules with high densities.

  14. Hybrid polymer-lipid films as platforms for directed membrane protein insertion.

    PubMed

    Kowal, Justyna; Wu, Dalin; Mikhalevich, Viktoria; Palivan, Cornelia G; Meier, Wolfgang

    2015-05-05

    Hybrids composed of amphiphilic block copolymers and lipids constitute a new generation of biological membrane-inspired materials. Hybrid membranes resulting from self-assembly of lipids and polymers represent adjustable models for interactions between artificial and natural membranes, which are of key importance, e.g., when developing systems for drug delivery. By combining poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) amphiphilic copolymers (PDMS-b-PMOXA) with various phospholipids, we obtained hybrid films with modulated properties and topology, based on phase separation, and the formation of distinct domains. By understanding the factors driving the phase separation in these hybrid lipid-polymer films, we were able to use them as platforms for directed insertion of membrane proteins. Tuning the composition of the polymer-lipids mixtures favored successful insertion of membrane proteins with desired topological distributions (in polymer or/and lipid regions). Controlled insertion and location of membrane proteins in hybrid films make these hybrids ideal candidates for numerous applications where specific spatial functionality is required.

  15. 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.

  16. In situ prepared polymer films as alignment layers for nematic liquid crystals

    SciTech Connect

    Pires, David; Galerne, Yves

    2006-12-15

    By means of UV-visible irradiations and convenient photoinitiators, we realize the cross-linked polymerization of a triacrylate monomer in solution in a nematic liquid crystal (p-pentyl-p{sup '}-cyanobiphenyl) at low concentrations (a few wt %), i.e., under conditions opposite to the synthesis of polymer-dispersed liquid crystals. As atomic force microscope measurements show, when operating close to, but below, the percolation transition, a thin polymer layer is synthesized in situ, directly covering and coating all the substrate. These observations therefore confirm that the properties of anchoring and of alignment memory previously observed in such nematic cells effectively originate from the synthesized polymer film. According to the photoinitiator used, bulk or surface polymerizations dominate and respectively produce continuous or discontinuous films (i.e., with separate clusters). In the former case, polymer aggregates are first synthesized. They then diffuse in the volume until they meet a surface, where they definitely stick if they are large enough. An estimate of the entropy and interaction energy differences between the two states, stuck or free, shows that the aggregates stick on the substrates if their size exceeds the length of about three monomers, i.e., if they contain more than 20-30 monomers. Interestingly, these films may be used to replicate nonuniform alignment patterns that are difficult to realize otherwise. The method may be considered as an imprinting method.

  17. Polymer-assisted conformal coating of TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Gillman, E. S.; Costello, D.; Moreno, M.; Raspopin, A.; Kasica, R.; Chen, L.

    2010-08-01

    Conformal coating of nanofabricated structures with a high-index dielectric material is a common problem for a diverse set of integrated photonic and plasmonic devices such as planar waveguides, on-chip spectrometers, gratings, flat panel displays, optical sensors, and integrated optical devices. In this paper we were recently able to demonstrate an alternate method for conformally coating photonic nanostructures using a low cost, polymer-assisted deposition (PAD) process for the metal-oxide TiO2. In a PAD process a thermally curable, hybrid high refractive index polymer solution is spin-coated onto a substrate. The polymer controls the viscosity and binds the metal ions, resulting in a homogeneous distribution of the precursor in solution. When cured at elevated temperature, the hybrid polymer coating decomposes to form a metal oxide-rich film that has a high refractive index that conformally fills the voids in nanofabricated structures. The resulting films have refractive indices higher than 1.83 in the visible region and film thicknesses between 250-500 nm depending on the level of metal-oxide loading, cure temperature, and number of coatings.

  18. An electrodeposited redox polymer-laccase composite film for highly efficient four-electron oxygen reduction

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Deng, Huimin; Teo, Alan Kay Liang; Gao, Zhiqiang

    2013-03-01

    In this report, it is shown that novel thin films of Os(dcbpy)2 (dcbpy = 4,4‧-dicarboxylic acid-2,2‧-bipyridine)-based redox polymer-laccase composite can be electrodeposited onto carbon electrodes under mild conditions. In a nutshell, the exchange of the inner-sphere Cl- of the Os(dcbpy)2Cl+/2+ complex tethered to partially quaternized poly (4-vinylpyridine) (PVP) by a pyridine ligand of a second PVP chain leads to cross-linking and deposition of the redox polymer. Laccase, which has coordinatively linkable functions of amines and histidines, is readily incorporated in the electrodeposited redox polymer. Because the reaction centers of the co-deposited laccase are electrically connected to the electrode through the deposited redox polymer, the electrodeposited film can catalyze the electroreduction of O2 at 0.58 V (vs. Ag/AgCl) - the least reducing potential for highly efficient four-electron reduction of O2 in pH 5.5 0.10 M phosphate buffer solution. Furthermore, the electroreduction of O2 is found to be O2 transport-limited when the reduction potential is poised at ≥120 mV more reducing than that of the reversible O2/H2O couple. This composite film could be an excellent candidate for uses as cathode in enzymatic biofuel cells.

  19. Electrodeposition of PANi films on platinum needle type microelectrodes. Application to the oxidation of ascorbate in human plasma.

    PubMed

    Bonastre, A M; Bartlett, P N

    2010-08-31

    Needle type (165 microm(2)) and small Pt disc (3-11 microm(2)) microelectrodes were used for the electrodeposition of composite poly(aniline), PANi, films by cyclic voltammetry and chronoamperometry for the oxidation of ascorbate. PANi electroactivity at neutral pH was retained through polymer alkylation or by using large poly-anions, such as poly(vinylsulfonate), PVS, and poly(styrenesulfonate), PSS. Hence the growth of the composite films was studied in the presence of different counter ions such as SO(4)(2-), Cl(-), NaPVS and NaPSS. The morphology of the resulting films was examined by scanning electron microscopy. Results showed that flat PANi films with thicknesses much lower than the microelectrode radius were obtained by potentiodynamic electrodeposition. On the other hand films with mushroom shapes, with significant spill over, were obtained under constant potential. The resulting polymer modified microelectrodes films were shown to be suitable for the oxidation of ascorbate at 0.1 V vs. SCE and pH 7 with a detection limit of 1 microM for PANi/PSS composites. The current was independent of film thickness, mass transport controlled at low ascorbate concentrations and not affected by the presence of common interferences such as uric acid, glutathione or vitamin E. Due to their excellent properties the PANi-PSS film coated microelectrodes were used for the amperometric detection of ascorbate in human plasma. The results are encouraging for the use of small polymer modified Pt needle type microelectrodes for the detection of ascorbate in biological systems.

  20. Polymer-Carbon Nanotube Composite Films at the Oil/Water Interface: Assembly and Properties

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Feng, Tao; Russell, Thomas P.

    2015-03-01

    Efficient carbon nanotube assembly at the oil/water interface was achieved by dissolving cationic polymers in the oil phase and oxidized nanotubes in the water phase, the two components spontaneously forming salt bridges to produce a composite interfacial film of nanoscopic thickness. As seen by pendant drop tensiometry, parameters such as carbon nanotube and polymer concentration, pH, polymer molecular weight, and degree of nanotube oxidation all affect assembly strongly, with measured trends to be described and explained. The frequency-dependent elastic and viscous moduli of films in dilation were characterized by interfacial pendant drop rheology. Structural (fast, minutes) and adsorption/desorption (slow, tens of minutes) relaxations were both noted, and at frequencies intermediate to the two, almost insensitive to assembly parameters, the films displayed expected behaviors for 2D critical gels, i.e., at the crossover between fluid and solid. Tan(delta) was frequency-independent over one to two decades of frequency, and the modulus of linear stress relaxation was a power law in time. Films wrinkled by larger (nonlinear) strains recovered over the structural relaxation time. Support: NSF-sponsored UMass MRSEC and the US DoE Office of Basic Energy Science through Contract DE-FG02-04ER46126.

  1. Intrinsic bond strength of metal films on polymer substrates

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Osaki, Hiroyuki

    1990-01-01

    A semiquantitative method for the measurement of the intrinsic bond strength between elastic substrates and elastic films that fail by brittle fracture is described. Measurements on a polyethylene terephthalate (PET)-Ni couple were used to verify the essential features of the analysis. It was found that the interfacial shear strength of Ni on PET doubled after ion etching.

  2. Super stretchy polymer multilayer thin films with tunable gas barrier

    NASA Astrophysics Data System (ADS)

    Xiang, Fangming; Ward, Sarah; Givens, Tara; Grunlan, Jaime

    2015-03-01

    Super stretchy multilayer thin film assemblies with tunable gas barrier were fabricated using layer-by-layer (LbL) assembly. Unlike ionically-bonded gas barrier coatings that exhibit mud-cracking after 10% strain, hydrogen-bonded polyethylene oxide (PEO) and polyacrylic acid (PAA) multilayer thin films show no cracking after 100% strain due to low modulus. It is believed that the exceptional elasticity of this thin film originates from the intrinsic elasticity of PEO and the moderate hydrogen bond strength between PEO and PAA. The oxygen transmission rate (OTR) of a 1.58 mm thick natural rubber sheet can be reduced 10 times with a 367-nm-thick PAA/PEO nanocoating. This gas barrier improvement is largely retained after 100% strain. The modulus and oxygen permeability of PAA/PEO assembly can be tailored through altering the assembling pH. By setting the assembling pH to 2.75, a 50% reduction in permeability can be achieved, while maintaining the elasticity of the assembly. These findings mark the first super stretchy gas barrier thin film, which is useful for elastomeric substrates designed to hold air pressure.

  3. Dynamics of Polymer Blend Film Formation During Spin Coating

    NASA Astrophysics Data System (ADS)

    Mouhamad, Youmna; Clarke, Nigel; Jones, Richard A. L.; Geoghegan, Mark

    2012-02-01

    Spin casting is a process broadly used to obtain a uniform film on a flat substrate. A homogeneous film results from the balance between centrifugal and viscous forces. Here we revisit the Meyerhofer model of the spin casting process by taking in account the centrifugal forces, a uniform time dependent evaporation rate, and account for the changes in viscosity using the Huggins intrinsic viscosity. Time resolved light reflectometry is used to monitor the thickness changes of a polystyrene-poly(methyl methacrylate)(which we denote as PS and PMMA) film initially dissolved in toluene and spin cast for ten seconds at 1000 rpm. The experimental data are in good agreement with the model. We also investigate how the volume fraction of PS and PMMA influences the thinning of the film during spin casting. A distinct change in the temporal evolution of thickness as a function of time delimits the first phase of the spin casting process where centrifugal forces are dominant from a second phase dominated by the solvent evaporation. This hypothesis is supported by in-situ off specular scattering data. The time at which this change from centrifugal to evaporation-dominated behaviour is delayed as the volume fraction of PMMA increases.

  4. Formation and control of line defects caused by tectonics of water droplet arrays during self-organized honeycomb-patterned polymer film formation.

    PubMed

    Yamazaki, Hidekazu; Ito, Koju; Yabu, Hiroshi; Shimomura, Masatsugu

    2014-04-28

    This study describes the formation of macro-scale defects of the honeycomb-patterned polymer film and we discovered two types of new line defects which differ from the defects reported in the past studies. We examined the formation mechanisms of the line defects and clarified two types of formation mechanisms of the "Divergent" mode line defects and the "Convergent" mode line defects caused by the "tectonics" of water droplet arrays on polymer solutions. The regions causing the macro-scale line defects are made clear in the phase diagram represented by the radius and the density of the micro-scale water droplets. In addition, the results of our calculations made it possible to theoretically predict the water droplet growth time for the water droplets to grow to the ideal size for uniform packing that is necessary for fabrication of the defect-free honeycomb-patterned polymer film. With the use of these techniques, A4-sized, defect-free, honeycomb-patterned polymer films can be fabricated.

  5. Gate-induced superconductivity in a solution-processed organic polymer film

    NASA Astrophysics Data System (ADS)

    Schön, J. H.; Dodabalapur, A.; Bao, Z.; Kloc, Ch.; Schenker, O.; Batlogg, B.

    2001-03-01

    The electrical and optical properties of conjugated polymers have received considerable attention in the context of potentially low-cost replacements for conventional metals and inorganic semiconductors. Charge transport in these organic materials has been characterized in both the doped-metallic and the semiconducting state, but superconductivity has not hitherto been observed in these polymers. Here we report a distinct metal-insulator transition and metallic levels of conductivity in a polymer field-effect transistor. The active material is solution-cast regioregular poly(3-hexylthiophene), which forms relatively well ordered films owing to self-organization, and which yields a high charge carrier mobility (0.05-0.1cm2V-1s-1) at room temperature. At temperatures below ~2.35K with sheet carrier densities exceeding 2.5 × 1014cm-2, the polythiophene film becomes superconducting. The appearance of superconductivity seems to be closely related to the self-assembly properties of the polymer, as the introduction of additional disorder is found to suppress superconductivity. Our findings therefore demonstrate the feasibility of tuning the electrical properties of conjugated polymers over the largest range possible-from insulating to superconducting.

  6. Polymer multilayer films obtained by electrochemically catalyzed click chemistry.

    PubMed

    Rydzek, Gaulthier; Thomann, Jean-Sébastien; Ben Ameur, Nejla; Jierry, Loïc; Mésini, Philippe; Ponche, Arnaud; Contal, Christophe; El Haitami, Alae E; Voegel, Jean-Claude; Senger, Bernard; Schaaf, Pierre; Frisch, Benoît; Boulmedais, Fouzia

    2010-02-16

    We report the covalent layer-by-layer construction of polyelectrolyte multilayer (PEM) films by using an efficient electrochemically triggered Sharpless click reaction. The click reaction is catalyzed by Cu(I) which is generated in situ from Cu(II) (originating from the dissolution of CuSO(4)) at the electrode constituting the substrate of the film. The film buildup can be controlled by the application of a mild potential inducing the reduction of Cu(II) to Cu(I) in the absence of any reducing agent or any ligand. The experiments were carried out in an electrochemical quartz crystal microbalance cell which allows both to apply a controlled potential on a gold electrode and to follow the mass deposited on the electrode through the quartz crystal microbalance. Poly(acrylic acid) (PAA) modified with either alkyne (PAA(Alk)) or azide (PAA(Az)) functions grafted onto the PAA backbone through ethylene glycol arms were used to build the PEM films. Construction takes place on gold electrodes whose potentials are more negative than a critical value, which lies between -70 and -150 mV vs Ag/AgCl (KCl sat.) reference electrode. The film thickness increment per bilayer appears independent of the applied voltage as long as it is more negative than the critical potential, but it depends upon Cu(II) and polyelectrolyte concentrations in solution and upon the reduction time of Cu(II) during each deposition step. An increase of any of these latter parameters leads to an increase of the mass deposited per layer. For given buildup conditions, the construction levels off after a given number of deposition steps which increases with the Cu(II) concentration and/or the Cu(II) reduction time. A model based on the diffusion of Cu(II) and Cu(I) ions through the film and the dynamics of the polyelectrolyte anchoring on the film, during the reduction period of Cu(II), is proposed to explain the major buildup features.

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

    PubMed Central

    Buck, Maren E.; Schwartz, Sarina C.

    2010-01-01

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

  8. Nanoscale direct mapping of localized and induced noise sources on conducting polymer films

    NASA Astrophysics Data System (ADS)

    Shekhar, Shashank; Cho, Duckhyung; Lee, Hyungwoo; Cho, Dong-Guk; Hong, Seunghun

    2015-12-01

    The localized noise-sources and those induced by external-stimuli were directly mapped by using a conducting-AFM integrated with a custom-designed noise measurement set-up. In this method, current and noise images of a poly(9,9-dioctylfluorene)-polymer-film on a conducting-substrate were recorded simultaneously, enabling the mapping of the resistivity and noise source density (NT). The polymer-films exhibited separate regions with high or low resistivities, which were attributed to the ordered or disordered phases, respectively. A larger number of noise-sources were observed in the disordered-phase-regions than in the ordered-phase regions, due to structural disordering. Increased bias-voltages on the disordered-phase-regions resulted in increased NT, which is explained by the structural deformation at high bias-voltages. On photo-illumination, the ordered-phase-regions exhibited a rather large increase in the conductivity and NT. Presumably, the illumination released carriers from deep-traps which should work as additional noise-sources. These results show that our methods provide valuable insights into noise-sources and, thus, can be powerful tools for basic research and practical applications of conducting polymer films.The localized noise-sources and those induced by external-stimuli were directly mapped by using a conducting-AFM integrated with a custom-designed noise measurement set-up. In this method, current and noise images of a poly(9,9-dioctylfluorene)-polymer-film on a conducting-substrate were recorded simultaneously, enabling the mapping of the resistivity and noise source density (NT). The polymer-films exhibited separate regions with high or low resistivities, which were attributed to the ordered or disordered phases, respectively. A larger number of noise-sources were observed in the disordered-phase-regions than in the ordered-phase regions, due to structural disordering. Increased bias-voltages on the disordered-phase-regions resulted in

  9. Gamma Knife relative dosimetry using VIP polymer gel and EBT radiochromic films

    NASA Astrophysics Data System (ADS)

    Moutsatsos, A.; Petrokokkinos, L.; Zourari, K.; Papagiannis, P.; Karaiskos, P.; Dardoufas, K.; Damilakis, J.; Seimenis, I.; Georgiou, E.

    2009-05-01

    The VIP polymer gel-MRI method and EBT Gafchromic films were employed to obtain relative dosimetry results for the Gamma Knife (GK) radiation fields of 4 mm and 18 mm nominal diameter. Results are compared to the corresponding calculations of GammaPlan Treatment Planning System (TPS) in the form of 1D profiles and 2D distributions. Measured and planned relative dosimetry datasets are found in close agreement within experimental uncertainties. A corresponding agreement is shown for Dose Volume Histogram (DVH) results that are available only through the application of the polymer gel method.

  10. Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers

    DTIC Science & Technology

    1994-05-31

    T Code: 4132016 W.H. Kim, B. Bihari, R. Moody, N. B. Kodali , J.KumarS.K. Dr. JoAnn Milliken Tripathy. 7. PHI-OUHMING OFH-NIZATION NAMIE(S) AND...Self Assembled Spin Coated and Bulk Films of a Novel Polydiacetylene as Second Order NLO Polymers by W.H. Kim, B. Bihari, R. Moody, N. B. Kodali ...POLYMERS W. H. Kim, B. Bihari+, R. Moody+, N. B. Kodali , J. Kumar+, and S. K. Tripathy, University of Massachusetts-Lowell, Center for Advanced Materials

  11. The Role of Heat Transfer during Reactive-Ion Etching of Polymer Films

    DTIC Science & Technology

    1990-05-07

    necessary and identify by block numb r ) - ,. •~~ ~ - r - e A ,: "I j _ - , -, ., I " jO " A study of the kinetics of 02i andArieactive-ion etching (RE) of...organic polymer films and an analysis of substrate heat transfer was carried out. Radiative heat transfer played a signifiu.ant role in determining the...absolutely no effect on etch rates of cross-linking polymers. To confirm the role of radiative heat transfer during RIE, the underside of a silicon

  12. Comparitive Astrometry with Kodak Type 4415 Tech Pan Film

    NASA Astrophysics Data System (ADS)

    Ianna, P. A.; Martin, J. C.

    1994-12-01

    With the demise of many commonly used Kodak Spectroscopic Plates attention has been directed toward alternative Kodak photographic materials for astronomical applications. Estar-based Kodak Type 4415 Tech Pan film is an attractive product owing to its very fine grain, ease of hypersensitization, excellent storage potential after hypering, and cost one tenth that of plates. We have endeavored to compare the relative astrometric precision of 4415 film and IIIaF plates. As nearly identical conditions as possible were maintained at each stage of the comparisons. Both film and plate were exposed in contact with the same GG495 filter, alternating film/plate exposures to approximately same limiting magnitude, and minimizing hour angle differences. Exposures from each night were developed in one darkroom session. The photographs were measured with our PDS 1010GM, the film emulsion side up held flat by the plate emulsion side down. Three film/plate pairs from the McCormick refractor and five film/plate pairs with the Fan 1 m reflector were used with ten stars in each comparison. We found standard errors for a single position to be +/- 0.76 microns for the 4415 film and +/- 0.21 microns for the IIIa-F glass plates. Further long-term comparisons are planned. This work is supported by the National Science Foundation and the Estate of Leander J. McCormick

  13. Nucleation type instabilities in partially wetting nanoscale nematic liquid films

    NASA Astrophysics Data System (ADS)

    Lam, Michael; Cummings, Linda; Kondic, Lou

    2016-11-01

    Nucleation type instabilities are studied in nematic liquid crystal (NLC) films with thicknesses less than a micrometer. Within the framework of the long wave approximation, a 4th order nonlinear partial differential equation is proposed for the free surface height. Unlike simple fluids, NLC molecules have a dipole moment which induces an elastic response due to deformation in the bulk of the fluid. The model includes the balance between the bulk elasticity energy and the anchoring (boundary) energy at the substrate and free surface, and van der Waals' intermolecular forces, by means of a structural disjoining pressure. In this presentation, we focus on two-dimensional flow and present simulation results for a flat film with a localized perturbation. We are interested in the morphology of the dewetted film as a function of the initial film thickness. We will show that there exists a range of film thicknesses within the linearly unstable flat film regime where stability analysis does not explain the morphology of the dewetted film. Marginal stability criterion (MSC) is used to derive an analytical expression for the velocity at which a perturbation propagates into the unstable flat film. Finally, we discuss the degree to which MSC can be used to explain the observed morphology.

  14. A comparative study of photoinduced deformation in azobenzene containing polymer films.

    PubMed

    Yadavalli, Nataraja Sekhar; Loebner, Sarah; Papke, Thomas; Sava, Elena; Hurduc, Nicolae; Santer, Svetlana

    2016-03-07

    In this paper two groups supporting different views on the mechanism of light induced polymer deformation argue about the respective underlying theoretical conceptions, in order to bring this interesting debate to the attention of the scientific community. The group of Prof. Nicolae Hurduc supports the model claiming that the cyclic isomerization of azobenzenes may cause an athermal transition of the glassy azobenzene containing polymer into a fluid state, the so-called photo-fluidization concept. This concept is quite convenient for an intuitive understanding of the deformation process as an anisotropic flow of the polymer material. The group of Prof. Svetlana Santer supports the re-orientational model where the mass-transport of the polymer material accomplished during polymer deformation is stated to be generated by the light-induced re-orientation of the azobenzene side chains and as a consequence of the polymer backbone that in turn results in local mechanical stress, which is enough to irreversibly deform an azobenzene containing material even in the glassy state. For the debate we chose three polymers differing in the glass transition temperature, 32 °C, 87 °C and 95 °C, representing extreme cases of flexible and rigid materials. Polymer film deformation occurring during irradiation with different interference patterns is recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the kinetics of film deformation. We also demonstrated the unique behaviour of azobenzene containing polymeric films to switch the topography in situ and reversibly by changing the irradiation conditions. We discuss the results of reversible deformation of three polymers induced by irradiation with intensity (IIP) and polarization (PIP) interference patterns, and the light of homogeneous intensity in terms of two approaches: the re-orientational and the photo-fluidization concepts. Both agree

  15. Adhesion between Polymers and Evaporated Gold and Nickel Films.

    DTIC Science & Technology

    1984-08-01

    on PTFE, about 5.49x10(exp 6) N/sq m on UHMWPE , and 6.54 x 10(exp 6) N/sq m on 6/6 nylon. The adhesion strengths for nickel films evaporated on PTFE... UHMWPE , and 6/6 nylon were found to be a factor of 1.7 higher than those for the gold-coated PTFE, UHMWPE , and 6/6 nylon. To confirm quantitatively

  16. Development of polymer-bound fast-dissolving metformin buccal film with disintegrants.

    PubMed

    Haque, Shaikh Ershadul; Sheela, Angappan

    2015-01-01

    Fast-dissolving drug-delivery systems are considered advantageous over the existing conventional oral dosage forms like tablets, capsules, and syrups for being patient friendly. Buccal films are one such system responsible for systemic drug delivery at the desired site of action by avoiding hepatic first-pass metabolism. Metformin hydrochloride (Met), an antidiabetic drug, has poor bioavailability due to its high solubility and low permeability. The purpose of the study reported here was to develop a polymer-bound fast-dissolving buccal film of metformin to exploit these unique properties. In the study, metformin fast-dissolving films were prepared by the solvent-casting method using chitosan, a bioadhesive polymer. Further, starch, sodium starch glycolate, and microcrystalline cellulose were the disintegrants added to different ratios, forming various formulations (F1 to F7). The buccal films were evaluated for various parameters like weight variation, thickness, folding endurance, surface pH, content uniformity, tensile strength, and percentage of elongation. The films were also subjected to in vitro dissolution study, and the disintegration time was found to be less than 30 minutes for all formulations, which was attributed to the effect of disintegrants. Formulation F6 showed 92.2% drug release within 6 minutes due to the combined effect of sodium starch glycolate and microcrystalline cellulose.

  17. Development of polymer-bound fast-dissolving metformin buccal film with disintegrants

    PubMed Central

    Haque, Shaikh Ershadul; Sheela, Angappan

    2015-01-01

    Fast-dissolving drug-delivery systems are considered advantageous over the existing conventional oral dosage forms like tablets, capsules, and syrups for being patient friendly. Buccal films are one such system responsible for systemic drug delivery at the desired site of action by avoiding hepatic first-pass metabolism. Metformin hydrochloride (Met), an antidiabetic drug, has poor bioavailability due to its high solubility and low permeability. The purpose of the study reported here was to develop a polymer-bound fast-dissolving buccal film of metformin to exploit these unique properties. In the study, metformin fast-dissolving films were prepared by the solvent-casting method using chitosan, a bioadhesive polymer. Further, starch, sodium starch glycolate, and microcrystalline cellulose were the disintegrants added to different ratios, forming various formulations (F1 to F7). The buccal films were evaluated for various parameters like weight variation, thickness, folding endurance, surface pH, content uniformity, tensile strength, and percentage of elongation. The films were also subjected to in vitro dissolution study, and the disintegration time was found to be less than 30 minutes for all formulations, which was attributed to the effect of disintegrants. Formulation F6 showed 92.2% drug release within 6 minutes due to the combined effect of sodium starch glycolate and microcrystalline cellulose. PMID:26491321

  18. Temperature modeling of laser-irradiated azo-polymer thin films.

    PubMed

    Yager, Kevin G; Barrett, Christopher J

    2004-01-08

    Azobenzene polymer thin films exhibit reversible surface mass transport when irradiated with a light intensity and/or polarization gradient, although the exact mechanism remains unknown. In order to address the role of thermal effects in the surface relief grating formation process peculiar to azo polymers, a cellular automaton simulation was developed to model heat flow in thin films undergoing laser irradiation. Typical irradiation intensities of 50 mW/cm2 resulted in film temperature rises on the order of 5 K, confirmed experimentally. The temperature gradient between the light maxima and minima was found, however, to stabilize at only 10(-4) K within 2 micros. These results indicate that thermal effects play a negligible role during inscription, for films of any thickness. Experiments monitoring surface relief grating formation on substrates of different thermal conductivity confirm that inscription is insensitive to film temperature. Further simulations suggest that high-intensity pulsed irradiation leads to destructive temperatures and sample ablation, not to reversible optical mass transport.

  19. Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

    PubMed Central

    Qu, Jing; Ouyang, Liangqi; Kuo, Chin-chen; Martin, David C.

    2015-01-01

    Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this study the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7 ± 0.3 MPa was determined. The addition of 5 mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4 ± 0.6 MPa. PMID:26607768

  20. Synthesis of transparent BaTiO3 nanoparticle/polymer composite film using DC field

    NASA Astrophysics Data System (ADS)

    Kondo, Yusuke; Okumura, Yasuko; Oi, Chifumi; Sakamoto, Wataru; Yogo, Toshinobu

    2008-10-01

    Transparent BaTiO3 nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing. BaTiO3 nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as 40°C. The crystallite size of BaTiO3 increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO3 nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO3 nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min.

  1. Stabilizing Surfactant Templated Cylindrical Mesopores in Polymer and Carbon Films through Composite Formation with Silica Reinforcement

    SciTech Connect

    Song, Lingyan; Feng, Dan; Lee, Hae-Jeong; Wang, Chengqing; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-10-22

    A facile approach to maintain the periodic mesostructure of cylindrical pores in polymer-resin and carbon films after thermal template removal is explored through the reactive coassembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock copolymer Pluronic F127. Without silica, a low porosity, disordered film is formed after pyrolysis despite the presence of an ordered mesostructure prior to template removal. However for silica concentration greater than 25 wt %, pyrolysis at 350 C yields a mesoporous silica-polymer film with well-defined pore mesostructure. These films remain well ordered upon carbonization at 800 C. In addition to the mesostructural stability, the addition of silica to the matrix impacts other morphological characteristics. For example, the average pore size and porosity of the films increase from 3.2 to 7.5 nm and 12 to 45%, respectively, as the concentration of silica in the wall matrix increases from 0 to 32 wt %. The improved thermal stability of the ordered mesostructure with the addition of silica to the matrix is attributed to the reinforcement of the mechanical properties leading to resistance to stress induced collapse of the mesostructure during template removal.

  2. Novel Organic Polymer Films for Real-time Holographic Processing

    DTIC Science & Technology

    2007-11-02

    Because of the modelo In behavior of the arctangent function, the range is wrapped (ambiguous) beyond the so-called synthetic wavelength TB01JMF.DOC...photorefractive polymer with high optical gain and diffraction efficiency near 100%", Nature ’ill, pp . 497-500 (1994). 2 S. Ducharme, J.C. Scott, R.J. Tweig...W.E. Moerner, Phys. Rev. Lett., 66, pp . 1846-1849 (1991). 3 W.E. Moerner and S.M. Silence, "Polymeric Photorefractive Materials", Chem. Rev. 94, pp

  3. One-step synthesis of magnetic chitosan polymer composite films

    NASA Astrophysics Data System (ADS)

    Cesano, Federico; Fenoglio, Gaia; Carlos, Luciano; Nisticò, Roberto

    2015-08-01

    In this study, a magnetic iron oxide-chitosan composite film is synthesized by one-step method and thoroughly investigated in order to better understand its inorganic/organic properties. A deep physico-chemical characterization of the magnetic films has been performed. In particular, the material composition was evaluated by means of XRD and ATR-FTIR spectroscopy, whereas the thermal stability and the subsequent inorganic phase transitions involving iron oxide species were followed by TGA analyses carried out at different experimental conditions (i.e. inert and oxidative atmosphere). The magnetic properties of the films were tested at the bulk and at the surface level, performing respectively magnetization hysteresis curve and magnetic force microscopy (MFM) surface mapping. Results indicate that the synthesized material can be prepared through a very simple synthetic procedure and suggests that it can be successfully applied for instance to environmental applications, such as the adsorption of contaminants from solid and liquid media thanks to its pronounced magnetic properties, which favour its recover.

  4. Ultrathin polytyramine films by electropolymerisation on highly doped p-type silicon electrodes

    NASA Astrophysics Data System (ADS)

    Losic, Dusan; Cole, Martin; Thissen, Helmut; Voelcker, Nicolas H.

    2005-06-01

    In recent years, silicon-based materials have been used extensively in device fabrication for sensors, microfluidic and biomaterial applications. In order to enhance the performance of the material, a number of surface functionalisations are employed. However, until now, silicon has not been used as an electrode material for electrodeposition of functional polymers. Here, highly doped p-type silicon was used as an electrode facilitating the electropolymerisation of ultrathin polytyramine (PT) films by cyclic voltammetry. The influence of resistivity, pre-treatment of the silicon surface and electrochemical conditions on the electropolymerisation process was studied. The results show that ultrathin PT films with a controlled thickness from 2 to 15 nm exhibit good electrochemical stability in buffer solution (pH 6.8) over a large potential window (-1.5 V to 1.5 V) and passivating properties towards a redox probe. In terms of the film morphology, a pinhole-free smooth surface with a roughness below 0.5 nm and with dominantly globular features of 40-60 nm diameter was observed by AFM. XPS characterisation showed that PT films display amine functional groups at the coating surface. UV induced silicon oxidation was used to prepare patterned PT films.

  5. An all-optical poling investigation of low absorbing azobenzene side-chain polymer films

    NASA Astrophysics Data System (ADS)

    Jia, Yajie; Wang, Gongming; Guo, Bin; Su, Wei; Zhang, Qijin

    2004-09-01

    All optical poling (AOP) processes of both the typical AOP material disperse red 1 (DR1) copolymer and a low absorbing side-chain poly(2-[4-(4-cyanophenylazo)phenoxy] hexyl methacrylate), called PCN6, were examined and compared. The trade-off between the optical seeding efficiency and the transparency of the nonlinear polymer was considered. Quasi-phase matched (QPM) second harmonic generation (SHG) in PCN6 films was demonstrated. A relaxation retardation effect of the photo-induced khgr(2) was also observed in thick PCN6 films.

  6. Time-resolved ultrathin cobalt film growth on a colloidal polymer template.

    PubMed

    Buffet, Adeline; Abul Kashem, Mottakin M; Schlage, Kai; Couet, Sébastien; Röhlsberger, Ralph; Rothkirch, André; Herzog, Gerd; Metwalli, Ezzeldin; Meier, Robert; Kaune, Gunar; Rawolle, Monica; Müller-Buschbaum, Peter; Gehrke, Rainer; Roth, Stephan V

    2011-01-04

    Cobalt (Co) sputter deposition onto a colloidal polymer template is investigated using grazing incidence small-angle X-ray scattering (GISAXS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). SEM and AFM data picture the sample topography, GISAXS the surface and near-surface film structure. A two-phase model is proposed to describe the time evolution of the Co growth. The presence of the colloidal template results in the correlated deposition of an ultrathin Co film on the sample surface and thus in the creation of Co capped polystyrene (PS) colloids. Well below the percolation threshold, the radial growth is restricted and only height growth is observed.

  7. Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

    NASA Technical Reports Server (NTRS)

    Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

    2002-01-01

    Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

  8. X-ray scattering from freestanding polymer films with geometrically curved surfaces.

    PubMed

    Lee, D R; Shin, K; Seeck, O H; Kim, Hyunjung; Seo, Y-S; Tolan, M; Rafailovich, M H; Sokolov, J; Sinha, S K

    2003-05-09

    We show that the x-ray surface scattering from a freestanding polymer film exhibits features that cannot be explained by the usual stochastic formalism for surfaces with random height fluctuations. Instead, a geometric description of the film morphology assuming two curved surfaces characterized by a radius of curvature and a lateral cutoff length successfully accounts for the phase difference between the Kiessig fringes of the nominal "specular" and "off-specular" components of the scattering. The formalism allows one to distinguish unambiguously between conformal and anticonformal curvature morphologies at long length scales.

  9. Small-angle light scattering from polymer-dispersed liquid-crystal films

    SciTech Connect

    Loiko, V. A. Maschke, U.; Zyryanov, V. Ya.; Konkolovich, A. V.; Misckevich, A. A.

    2008-10-15

    A method is developed for modeling and computing the angular distribution of light scattered forward from a single-layer polymer-dispersed liquid-crystal (PDLC) film. The method is based on effective-medium approximation, anomalous diffraction approximation, and far-field single-scattering approximation. The angular distribution of forward-scattered light is analyzed for PDLC films with droplet size larger than the optical wavelength. The method can be used to study field-and temperature-induced phase transitions in LC droplets with cylindrical symmetry by measuring polarized scattered light intensity.

  10. Surface imprinted thin polymer film systems with selective recognition for bovine serum albumin.

    PubMed

    Kryscio, David R; Peppas, Nicholas A

    2012-03-09

    Molecularly imprinted polymers are synthetic antibody mimics formed by the crosslinking of organic or inorganic polymers in the presence of an analyte which yields recognitive polymer networks with specific binding pockets for that biomolecule. Surface imprinted polymers were synthesized via a novel technique for the specific recognition of bovine serum albumin (BSA). Thin films of recognitive networks based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) as the functional monomer and varying amounts of either N,N'-methylenebisacrylamide (MBA) or poly(ethylene glycol) (400) dimethacrylate (PEG400DMA) as the crosslinking agent were synthesized via UV free-radical polymerization and characterized. A clear and reproducible increase in recognition of the template BSA was demonstrated for these systems at 1.6-2.5 times more BSA recognized by the MIP sample relative to the control polymers. Additionally, these polymers exhibited selective recognition of the template relative to competing proteins with up to 2.9 times more BSA adsorbed than either glucose oxidase or bovine hemoglobin. These synthetic antibody mimics hold significant promise as the next generation of robust recognition elements in a wide range of bioassay and biosensor applications.

  11. Erasable thin-film optical diode based on a photoresponsive liquid crystal polymer

    NASA Astrophysics Data System (ADS)

    Zhang, Xinping; Zhang, Jian; Sun, Yujian; Yang, Huai; Yu, Haifeng

    2014-03-01

    We report a thin-film optical diode written into thin films of a liquid-crystalline polymer (LCP), which is based on the photoinduced LC-to-isotropic phase transition of LCPs. The interference pattern between a collimated and a focused UV laser beam is imprinted as chirped volume-phase gratings in photoresponsive LCP films and no further processing steps like development or liftoff are required for the fabrication. The resultant thin-film device not only possesses the fundamental functions of an optical lens for laser beam focusing, but also shows diode effects with the focusing/defocusing function dependent on the direction of light incidence and orientation of the device. Furthermore, this photonic thin-film lens exhibits a spatially tunable spectroscopic response, revealing a unique physics of secondary excitations of resonance modes of the single-layer LCP waveguide grating structures. This reveals the mechanisms for the focusing/defocusing of laser beams by chirped grating structures. Erasability and reconstructibility of the photoresponsive LCPs guarantee rewritability of the thin-film diode lens.We report a thin-film optical diode written into thin films of a liquid-crystalline polymer (LCP), which is based on the photoinduced LC-to-isotropic phase transition of LCPs. The interference pattern between a collimated and a focused UV laser beam is imprinted as chirped volume-phase gratings in photoresponsive LCP films and no further processing steps like development or liftoff are required for the fabrication. The resultant thin-film device not only possesses the fundamental functions of an optical lens for laser beam focusing, but also shows diode effects with the focusing/defocusing function dependent on the direction of light incidence and orientation of the device. Furthermore, this photonic thin-film lens exhibits a spatially tunable spectroscopic response, revealing a unique physics of secondary excitations of resonance modes of the single-layer LCP

  12. Electrocatalytic hydrogenation using precious metal microparticles in redox-active polymer films

    SciTech Connect

    Coche, L.; Ehui, B.; Limosin, D.; Moutet, J.C. )

    1990-11-09

    Glassy carbon felt electrodes have been modified by electrodeposition of poly(pyrrole-viologen) films (derived from N,N{prime}-dialkyl-4,4{prime}-bipyridinium salts), followed by electroprecipitation of precious metal (Pt, Pd, Rh, or Ru) microparticles. The resulting electrodes have been proved to be active for the electrocatalytic hydrogenation of conjugated enones (2-cyclohexen-1-one, cryptone, carvone, isophorone), styrene, and benzonitrile in aqueous media (pH 1). Despite low loadings of metal catalysts, high electric and products yields and a long term stability of these cathodes have been observed. The influence of the metal loading and the polymer structure on the catalytic efficiency as well as the selectivity obtained according to the metal catalyst used have been studied. Comparison with results previously reported for other catalytic cathodes like Pt/Pt, Pd/C, or Raney nickel electrodes proves the high efficiency of these metal microparticles within redox polymer film based electrodes.

  13. Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

    NASA Astrophysics Data System (ADS)

    Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

    2016-01-01

    In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

  14. Low bending loss metal waveguide embedded in a free-standing multilayered polymer film.

    PubMed

    Lee, Jong-Moo; Park, Suntak; Kim, Min-su; Park, Seung Koo; Kim, Jin Tae; Choe, Joong-Seon; Lee, Wook-Jae; Lee, Myung-Hyun; Ju, Jung Jin

    2009-01-05

    Very low vertical bending loss is demonstrated in a flexible metal waveguide. The waveguide consists of an 8 nm-thick and 68 mm-long Ag strip embedded in a free-standing multilayered low-loss polymer film. The polymer film is composed of a 10 microm-thick inner cladding with a refractive index of 1.524, and a pair of 20 microm-thick outer claddings which both have a refractive index of 1.514, resulting in a total thickness of 50 microm. The measured vertical bending loss is lower than 0.3 dB/180 masculine at a wavelength of 1310 nm for the bending radii down to 2 mm.

  15. Fabrication of microstructured polymer films using breath-figure-templated assembly

    NASA Astrophysics Data System (ADS)

    Srinivasarao, Mohan; Sharma, Vivek; Crne, Matija

    2010-03-01

    Breath figures formed on evaporating polymer solutions exposed to the blast of humid air involve growth and self-assembly of water drops that are non-coalescent. The ordered arrays of nearly monodisperse drops, eventually evaporate away, leaving a microstructured, porous polymer film. We elucidate the mechanism of this breath-figure-templated assembly, by accounting for various transport and thermodynamic processes that control the dynamics of drop nucleation, growth, noncoalescence and self-assembly. The theoretical framework developed in this study allows one to rationalize and predict the structure and size of pores. We provide an exemplary study where we use coat these films with inorganic oxides and mimic the structural color of Papilio palinurus butterfly.

  16. Thin liquid film in polymer tubing : dynamics and dewetting in partial wetting condition

    NASA Astrophysics Data System (ADS)

    Hayoun, Pascaline; Letailleur, Alban; Teisseire, Jérémie; Verneuil, Emilie; Lequeux, François; Barthel, Etienne

    2015-11-01

    Polymers such as PVC and Silicone are low cost materials widely used in industry to produce tubing for fluid transport. Most of these applications involve repeated, intermittent flow of liquids which can lead to unwanted contamination. This study aims at better understanding contamination mechanisms during intermittent flow in polymer tubing, and at elucidating the relation between flow, wetting and contamination. We experimentally and theoretically investigate, flow regimes as well as dewetting process at the triple line induced by gravity flow of a vertical liquid slug in a cylindrical geometry. Our results for Newtonian fluids evidence a succession of thick film formation, hydraulic jump creation in the thickness profile, oscillatory regime and destabilization leading to substrate contamination. In order to understand theoretically the flow, one crucial quantity to assess is the film thickness in the inside of the tube. Based on an absorption measurement method, we provide explanations for behaviors and flow regimes observed experimentally.

  17. Molecular Water Lilies: Orienting Single Molecules in a Polymer Film by Solvent Vapor Annealing.

    PubMed

    Würsch, Dominik; Hofmann, Felix J; Eder, Theresa; Aggarwal, A Vikas; Idelson, Alissa; Höger, Sigurd; Lupton, John M; Vogelsang, Jan

    2016-11-17

    The microscopic orientation and position of photoactive molecules is crucial to the operation of optoelectronic devices such as OLEDs and solar cells. Here, we introduce a shape-persistent macrocyclic molecule as an excellent fluorescent probe to simply measure (i) its orientation by rotating the excitation polarization and recording the strength of modulation in photoluminescence (PL) and (ii) its position in a film by analyzing the overall PL brightness at the molecular level. The unique shape, the absorption and the fluorescence properties of this probe yield information on molecular orientation and position. We control orientation and positioning of the probe in a polymer film by solvent vapor annealing (SVA). During the SVA process the molecules accumulate at the polymer/air interface, where they adopt a flat orientation, much like water lilies on the surface of a pond. The results are potentially significant for OLED fabrication and single-molecule spectroscopy (SMS) in general.

  18. Studying the Performance of Conductive Polymer Films as Textile Electrodes for Electrical Bioimpedance Measurements

    NASA Astrophysics Data System (ADS)

    Cunico, F. J.; Marquez, J. C.; Hilke, H.; Skrifvars, M.; Seoane, F.

    2013-04-01

    With the goal of finding novel biocompatible materials suitable to replace silver in the manufacturing of textile electrodes for medical applications of electrical bioimpedance spectroscopy, three different polymeric materials have been investigated. Films have been prepared from different polymeric materials and custom bracelets have been confectioned with them. Tetrapolar total right side electrical bioimpedance spectroscopy (EBIS) measurements have been performed with polymer and with standard gel electrodes. The performance of the polymer films was compared against the performance of the gel electrodes. The results indicated that only the polypropylene 1380 could produce EBIS measurements but remarkably tainted with high frequency artefacts. The influence of the electrode mismatch, stray capacitances and large electrode polarization impedance are unclear and they need to be clarified with further studies. If sensorized garments could be made with such biocompatible polymeric materials the burden of considering textrodes class III devices could be avoided.

  19. Photoconductivity of organic polymer films doped with porous silicon nanoparticles and ionic polymethine dyes

    SciTech Connect

    Davidenko, N. A. Skrichevsky, V. A.; Ishchenko, A. A.; Karlash, A. Yu.; Mokrinskaya, E. V.

    2009-05-15

    Features of electrical conductivity and photoconductivity of polyvinylbutyral films containing porous silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with different ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of porous silicon nanoparticles. It is assumed that the electronic conductivity in porous silicon nanoparticles is higher in comparison with p-type conductivity.

  20. Flexibility and color monitoring of cellulose nanocrystal iridescent solid films using anionic or neutral polymers.

    PubMed

    Bardet, Raphael; Belgacem, Naceur; Bras, Julien

    2015-02-25

    One property of sulfated cellulose nanocrystals (CNCs) is their ability to self-assemble from a concentrated suspension under specific drying conditions into an iridescent film. Such colored films are very brittle, which makes them difficult to handle or integrate within an industrial process. The goal of this study is (i) to produce flexible films using neutral poly(ethylene glycol) (PEG) and (ii) to modulate their coloration using an anionic polyacrylate (PAAS). The first part is dedicated to studying the physicochemical interactions of the two polymers with CNCs using techniques such as zeta potential measurements, dynamic light scattering (DLS), quartz crystal microbalance (QCM), and atomic force microscopy (AFM). Iridescent solid films were then produced and characterized using scanning electron microscopy (SEM) and UV-visible spectroscopy. The mechanical and thermal properties of films incorporating CNC were measured to evaluate improvements in flexibility. The addition of 10 wt % of PEG makes these films much more flexible (with a doubling of the elongation), with the coloration being preserved and the temperature of degradation increasing by almost 35 °C. Up to 160 μmol/gCNC PAAS can be added to tune the coloration of the CNC films by producing a more narrow, stronger coloration in the visible spectrum (higher absorption) with a well-pronounced fingerprint texture.

  1. Note: A single specimen channel crack growth technique applied to brittle thin films on polymer substrates

    NASA Astrophysics Data System (ADS)

    Kim, K.; Graham, S.; Pierron, O. N.

    2017-03-01

    We introduce an external-load-assisted thin film channel crack growth technique to measure the subcritical crack growth properties of thin films (i.e., crack velocity, v, versus the strain energy release rate, G), and demonstrate it using 250-nm-thick SiNx films on poly(ethylene terephthalate) substrates. The main particularity of this technique is that it requires a polymer substrate to allow loading to large strains (in order to induce channel cracking) without substrate fracture. Its main advantages are to provide a full v-G curve with a single specimen while relying on a simple specimen preparation and straightforward crack growth characterization. Importantly, the technique can be employed for a much larger range of thin films compared to the residual-stress-driven, thin film channel crack growth tests, including ultrathin films and thin film with residual compressive stresses. The restrictions to a proper use of this technique, related to the (visco)plastic deformation of the substrate, are discussed.

  2. Layer-by-layer structured polymer/TiO2 thin film and its gate dielectric application.

    PubMed

    Park, Bong Jun; Park, Jae Hoon; Choi, Jong Sun; Choi, Hyoung Jin

    2010-07-01

    Composite materials of the polymer and inorganic dielectric material have been investigated due to synergistic effect of both flexible properties of the polymer and dielectric properties of the inorganic material. In this study, poly(methyl methacrylate-co-methacrylic acid)/titanium dioxide (PMMA-co-MAA/TiO2) bilayer films were fabricated using a spin coating method followed by a self assembled sol-gel process and then examined for a gate dielectric application of the OTFT. Fracture and surface morphologies of the bilayer film on silicon wafer was observed via both SEM and AFM. Dielectric constant of the composite film synthesized was found to be larger than that of pure polymer film. In addition, with pentacene as a conducting layer, device performance of the composite film was characterized, and it was found that the threshold gate voltage was reduced while the field induced current was increased.

  3. Chemically modified carbon nanostructures for electrospun thin film polymer-nanocomposites

    NASA Astrophysics Data System (ADS)

    Behler, Kristopher

    Various nano-structured carbon materials, most notably carbon nanotubes (CNTs) and nanodiamonds (NDs), are used in preparing polymer-nanocomposites. Surface-modified NDs, multi-walled (MWCNT), double-walled (DWCNT) and triple-walled (TWCNT) have been incorporated into polymer matrix systems. Treatments include vacuum annealing, thermal oxidation in air and acid treatments (nitric and sulfuric acids for the CNTs and hydrochloric acid for NDs). Acid treatments have led to carboxylic group formation on the surface of CNTs and NDs, promoting improved dispersion. As-received, thermal and acid treated MWCNTs have been incorporated into polyvinylidene fluoride and polyamide-11 and -12 electrospun nanofibers with little improvements in the electrical conductivity. To improve the electrical properties of CNT-polyamide composites, negatively charged CNTs were self-assembled on the nanofiber's surface. At a 2 wt% loading, the electrical resistance of the nanofibers decreased two orders of magnitude (to 154 O/sq) by increasing the number of MWCNT self-assembly depositions and then another three orders of magnitude by using DWCNTs (700 O/sq). Further heat treatments were used to fuse (110°C) and completely remove the nanofibers (450°C) to produce ˜150 nm coatings with improved transparency, ˜96% transmission, in the visible spectrum. HCl-purified NDs have also been successfully incorporated in polyamide 11 and polyacrylonitrile nanofibers leading to improvements in the mechanical properties of the fibers. Extremely high loadings of up to 90 wt% ND in the polymer have also been achieved. The Young's modulus of the ND-polyamide-11 composites increased by a factor of four, the hardness doubled and the scratch resistance was improved such that a load three times larger than used on the pure polymer was required to generate a scratch of the identical depth in the composite material. The ND-polymer films have shown about a 50% decrease in transmission in the UV-range, making

  4. Out-of-plane orientation alignment and reorientation dynamics of gold nanorods in polymer nanocomposite films.

    PubMed

    Glor, Ethan C; Ferrier, Robert C; Li, Chen; Composto, Russell J; Fakhraai, Zahra

    2017-03-15

    In this work, we develop a novel, in situ characterization method to measure the orientation order parameter and investigate the reorientation and reshaping dynamics of polymer grafted gold nanorods (AuNRs) in polymer nanocomposite (PNC) thin films. The long aspect-ratio of AuNRs results in two well-defined plasmon resonance modes, allowing the optical properties of the PNC to be tuned over a wide spectral range. The alignment of the AuNRs in a particular direction can also be used to further tune these optical properties. We utilize variable angle spectroscopic ellipsometry as a unique technique to measure the optical properties of PNC films containing AuNRs at various angles of incidence, and use effective index of refraction analysis of the PNC to relate the birefringence in the film due to changes of the plasmon coupling to the orientation order parameter of AuNRs. Polymer thin films (ca. 70 nm) of either polystyrene (PS) or poly(methyl methacrylate) (PMMA) containing PS grafted AuNRs are probed with ellipsometry, and the resulting extinction coefficient spectra compare favorably with more traditional analytical techniques, electron microscopy (EM) and optical absorbance (vis-NIR) spectroscopy. Furthermore, variable angle spectroscopic ellipsometry measures optical birefringence, which allows us to determine the in- and out-of plane order of the AuNRs, a property that is not easily accessible using other measurement techniques. Additionally, this technique is applied in situ to demonstrate that AuNRs undergo a rapid (ca. 1-5 hours) reorientation before undergoing a slower (ca. 24 hours) rod to sphere shape transition. The reorientation behavior is different depending on the polymer matrix used. In the athermal case (i.e. PS matrix), the AuNRs reorient isotropically, while in PMMA the AuNRs do not become isotropic, which we hypothesize is due to PMMA preferentially wetting the silica substrate, leaving less vertical space for the AuNRs to reorient.

  5. Stochastic model for photoinduced surface relief grating formation through molecular transport in polymer films.

    SciTech Connect

    Juan, M.; Plain, J.; Bachelot, R.; Royer, P.; Gray, S. K.; Wiederrecht, G. P.; Univ. de Technologie de Troyes

    2008-09-01

    We use a stochastic model to study photoinduced surface relief grating (SRG) formation due to molecular transport in azobenzene polymer films. The model is shown to reproduce the essential experimental features of SRG formation. In particular, it predicts SRG formation under both p and s polarizations, and the double peaked topographies that can occur at early times of the process. The evolving molecular positions and orientations during exposure are also followed, providing a useful mechanistic picture of SRG dynamics.

  6. Stochastic model for photoinduced surface relief grating formation through molecular transport in polymer films

    SciTech Connect

    Juan, M. L.; Plain, J.; Bachelot, R.; Royer, P.; Gray, S. K.; Wiederrecht, G. P.

    2008-10-13

    We use a stochastic model to study photoinduced surface relief grating (SRG) formation due to molecular transport in azobenzene polymer films. The model is shown to reproduce the essential experimental features of SRG formation. In particular, it predicts SRG formation under both p and s polarizations, and the double peaked topographies that can occur at early times of the process. The evolving molecular positions and orientations during exposure are also followed, providing a useful mechanistic picture of SRG dynamics.

  7. Electrically switchable Fresnel lens using a polymer-separated composite film.

    PubMed

    Fan, Yun-Hsing; Ren, Hongwen; Wu, Shin-Tson

    2005-05-30

    A Fresnel lens with electrically-tunable diffraction efficiency while possessing high image quality is demonstrated using a phase-separated composite film (PSCOF). The light scattering-free PSCOF is obtained by anisotropic phase separation between liquid crystal and polymer. Such a lens can be operated below 12 volts and its switching time is reasonably fast (~10 ms). The maximum diffraction efficiency reaches ~35% for a linearly polarized light, which is close to the theoretical limit of 41%.

  8. Creating opal-templated continuous conducting polymer films with ultralow percolation thresholds using thermally stable nanoparticles.

    PubMed

    Kang, Dong Jin; Kwon, Taegyun; Kim, Minsoo P; Cho, Chul-Hee; Jung, Hyunjung; Bang, Joona; Kim, Bumjoon J

    2011-11-22

    We propose a novel and robust strategy for creating continuous conducting polymer films with ultralow percolation thresholds using polymer-coated gold nanoparticles (Au NPs) as surfactant. Continuous poly(triphenylamine) (PTPA) films of high internal phase polymeric emulsions were fabricated using an assembly of cross-linked polystyrene (PS) colloidal particles as template. Polymer-coated Au NPs were designed to be thermally stable even above 200 °C and neutral to both the PS and PTPA phases. Therefore, the Au NPs localize at the PS/PTPA interface and function as surfactant to efficiently produce a continuous conducting PTPA polymer film with very low percolation thresholds. The volume fraction threshold for percolation of the PTPA phase with insulating PS colloids (as measured by electron microscopy and conductivity measurements) was found to be 0.20. In contrast, with the addition of an extremely low volume fraction (φ(p) = 0.35 vol %) of surfactant Au NPs, the volume fraction threshold for percolation of the PTPA phase was dramatically reduced to 0.05. The SEM and TEM measurements clearly demonstrated the formation of a continuous PTPA phase within the polyhedral phase of PS colloids. To elucidate the influence of the nanoparticle surfactant on the blend films, the morphology and conductivity of the blends at different PS colloid/PTPA volume ratios were carefully characterized as a function of the Au NP concentration. Our approach provides a methodology for a variety of applications that require a continuous phase for the transport of molecular species, ions, or electrons at low concentrations and a second phase for mechanical support or the conduction of a separate species.

  9. DNA-SMART: Biopatterned Polymer Film Microchannels for Selective Immobilization of Proteins and Cells.

    PubMed

    Schneider, Ann-Kathrin; Nikolov, Pavel M; Giselbrecht, Stefan; Niemeyer, Christof M

    2017-02-22

    A novel SMART module, dubbed "DNA-SMART" (DNA substrate modification and replication by thermoforming) is reported, where polymer films are premodified with single-stranded DNA capture strands, microthermoformed into 3D structures, and postmodified with complementary DNA-protein conjugates to realize complex biologically active surfaces within microfluidic devices. As a proof of feasibility, it is demonstrated that microchannels presenting three different proteins on their inner curvilinear surface can be used for selective capture of cells under flow conditions.

  10. The change in dielectric constant, AC conductivity and optical band gaps of polymer electrolyte film: Gamma irradiation

    SciTech Connect

    Raghu, S. Subramanya, K. Sharanappa, C. Mini, V. Archana, K. Sanjeev, Ganesh Devendrappa, H.

    2014-04-24

    The effects of gamma (γ) irradiation on dielectric and optical properties of polymer electrolyte film were investigated. The dielectric constant and ac conductivity increases with γ dose. Also optical band gap decreased from 4.23 to 3.78ev after irradiation. A large dependence of the polymer properties on the irradiation dose was noticed. This suggests that there is a possibility of improving polymer electrolyte properties on gamma irradiation.

  11. 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.

  12. Static deflection measurements of cantilever arrays reveal polymer film expansion and contraction.

    PubMed

    Snow, David; Weeks, Brandon L; Kim, Dae Jung; Loui, Albert; Hart, Bradley R; Hope-Weeks, Louisa J

    2007-12-15

    An optical static method of detection is used to interpret surface stress induced bending related to cantilevers coated on one side with poly(vinyl alcohol), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), and poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), or respectively, PVA, PVB, and PVC, and exposed to various solvent vapors. Results indicate that the adsorption and surface interactions of the different solvent vapors that cause polymer swelling and shrinking lead to rearrangements, which have been shown to change the elastic properties of the polymer film, and subsequently, the spring constant of the polymer coated cantilever. Static deflection measurements allow the direction of cantilever bending to be determined, which adds a new dimension of usefulness for surface functionalized cantilevers as transducers in the development of novel microelectromechanical systems (MEMS).

  13. Optical properties of self-organized gold nanorod-polymer hybrid films.

    PubMed

    Tritschler, Ulrich; Zlotnikov, Igor; Keckeis, Philipp; Schlaad, Helmut; Cölfen, Helmut

    2014-11-25

    High fractions of gold nanorods were locally aligned by means of a polymeric liquid crystalline phase. The gold nanorods constituting >80 wt % of the thin organic-inorganic composite films form a network with side-by-side and end-to-end combinations. Organization into these network structures was induced by shearing gold nanorod-LC polymer dispersions via spin-coating. The LC polymer is a polyoxazoline functionalized with pendent cholesteryl and carboxyl side groups enabling the polymer to bind to the CTAB stabilizer layer of the gold nanorods via electrostatic interactions, thus forming the glue between organic and inorganic components, and to form a chiral nematic lyotropic phase. The self-assembled locally oriented gold nanorod structuring enables control over collective optical properties due to plasmon resonance coupling, reminiscent of enhanced optical properties of natural biomaterials.

  14. Methods and Materials for Selective Modification of Photopatterned Polymer Films.

    DTIC Science & Technology

    1999-06-28

    A Serial Number * Filing Date Inventor 09/339.917 28 June 1999 Susan L . Brandow Jeffrey M. Calvert Walter J. Dressick...bound in both the amine and silanol regions in a ratio of- 14:1, respectively ( L . A . Chrisey, P.M. Roberts, V.l. Benezra, W.J. Dressick, C.S. Dulcey...Beer’s law: b= A /(2ec), where A was the measured film absorbance, e (=55,000 L molc’cm𔃻) was the molar extinction coefficient measured for a known

  15. Interfacial design and structure of protein/polymer films on oxidized AlGaN surfaces

    NASA Astrophysics Data System (ADS)

    Gupta, Samit K.; Wu, Hao-Hsuan; Kwak, Kwang J.; Casal, Patricia; Nicholson, Theodore R., III; Wen, Xuejin; Anisha, R.; Bhushan, Bharat; Berger, Paul R.; Lu, Wu; Brillson, Leonard J.; Lee, Stephen Craig

    2011-01-01

    Protein detection using biologically or immunologically modified field-effect transistors (bio/immunoFETs) depends on the nanoscale structure of the polymer/protein film at sensor interfaces (Bhushan 2010 Springer Handbook of Nanotechnology 3rd edn (Heidelberg: Springer); Gupta et al 2010 The effect of interface modification on bioFET sensitivity, submitted). AlGaN-based HFETs (heterojunction FETs) are attractive platforms for many protein sensing applications due to their electrical stability in high osmolarity aqueous environments and favourable current drive capabilities. However, interfacial polymer/protein films on AlGaN, though critical to HFET protein sensor function, have not yet been fully characterized. These interfacial films are typically comprised of protein-polymer films, in which analyte-specific receptors are tethered to the sensing surface with a heterobifunctional linker molecule (often a silane molecule). Here we provide insight into the structure and tribology of silane interfaces composed of one of two different silane monomers deposited on oxidized AlGaN, and other metal oxide surfaces. We demonstrate distinct morphologies and wear properties for the interfacial films, attributable to the specific chemistries of the silane monomers used in the films. For each specific silane monomer, film morphologies and wear are broadly consistent on multiple oxide surfaces. Differences in interfacial film morphology also drive improvements in sensitivity of the underlying HFET (coincident with, though not necessarily caused by, differences in interfacial film thickness). We present a testable model of the hypothetical differential interfacial depth distribution of protein analytes on FET sensor interfaces with distinct morphologies. Empirical validation of this model may rationalize the actual behaviour of planar immunoFETs, which has been shown to be contrary to expectations of bio/immunoFET behaviour prevalent in the literature for the last 20 years

  16. Synthesis and characterization of polymer-silica hybrid latexes and sol-gel-derived films

    NASA Astrophysics Data System (ADS)

    Petcu, Cristian; Purcar, Violeta; Ianchiş, Raluca; Spătaru, Cătălin-Ilie; Ghiurea, Marius; Nicolae, Cristian Andi; Stroescu, Hermine; Atanase, Leonard-Ionuţ; Frone, Adriana Nicoleta; Trică, Bogdan; Donescu, Dan

    2016-12-01

    Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Sisbnd Osbnd Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

  17. Programming Surface Energy Driven Marangoni Convection in Polymer Thin Films to Generate Topographic Patterns

    NASA Astrophysics Data System (ADS)

    Kim, Chae Bin; Janes, Dustin; Arshad, Talha; Katzenstein, Joshua; Prisco, Nathan; McGuffin, Dana; Bonnecaze, Roger; Ellison, Christopher

    2015-03-01

    The Marangoni effect describes how fluid flows in response to gradients in surface energy. We recently developed a method for photochemically preprograming spatial surface energy patterns in glassy polystyrene (PS) thin films. UV irradiation through a mask selectively dehydrogenates the PS, thus increasing surface energy in the UV exposed regions compared to the unexposed regions. After heating the film to the liquid state, transport of polymer occurs from regions of low surface energy to regions of high surface energy. This method can be harnessed to rapidly manufacture polymer films possessing prescribed three-dimensional topographies reflective of the original light exposure pattern. To quantify and verify this phenomenon, a theoretical model that gives a more thorough understanding of the physics of this process, its limits and ways to apply it efficiently for various target metrics will also be presented along with comparisons between theoretical predictions and experimental observations. Finally, while PS dehydrogenation can be used to produce a variety of topographical patterns, judicious selection of the photosensitizing compounds in an otherwise transparent polymer expands the use of this method to more readily available light sources.

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

    SciTech Connect

    Michael E. Mackay

    2009-03-04

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

  19. Optical behavior of silver nanoparticles embedded in polymer thin film layers

    NASA Astrophysics Data System (ADS)

    Carlberg, M.; Pourcin, F.; Margeat, O.; Le Rouzo, J.; Berginc, G.; Sauvage, R.-M.; Ackermann, J.; Escoubas, L.

    2016-09-01

    The study of metal nanoparticles (NPs) is challenging for the control of the light matter interaction phenomena. In this context, our work is focused on optical characterization and modeling of polymer thin films layers with inclusions of previously chemically synthesized NPs. Through the presence of metallic NPs in polymer thin films, the optical properties are assumed to become tunable. Thin film layers with inclusions of differently shaped and sized silver NPs, such as nanospheres and nanoprisms, are optically characterized to get the scattering, the reflection and the absorption of the layers. One step and two step seed based methods of silver ions reduction are used for the chemical synthesis of nanospheres and nanoprisms. The plasmonic resonance peaks of these colloidal solutions range from 360 to 1300 nm. A poly vinyl pyrrolidone (PVP) polymer matrix is chosen for its light non-absorbing and NP-stabilizing properties. Knowledge on the shape and size of the NPs embedded in the spin coated layers is obtained by transmission electron microscopy (TEM) imaging. The optical properties include spectrophotometry and spectroscopic ellipsometry (SE) measurements to get the reflectance, the transmittance, the absorptance and the optical indices n and k of the heterogeneous layers. A redshift in absorption is measured between deposited nanospheres and other shaped NPs. FDTD simulations allow calculation of far and near field properties. The visualization of the NP interactions and the electric field enhancement, on and around the NPs, are studied to improve the understanding of the far field properties.

  20. Electrochemical properties of multilayer film assembled by layer-by-layer adsorption of redox polymer

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Zheng, Haitao; Liu, Shiyang; Liu, Pu; Zhou, Jingli; Suye, Shin-ichiro

    2009-07-01

    A redox polymer, poly(ethylenimine)ferrocene (PEI-Fc) was prepared by attaching electroactive ferrocene groups to the backbone of a water soluble, biocompatible polyelectrolyte, poly(ethylenimine), and multilayer film composed of polystyrenesulfonate sodium (PSS) and PEI-Fc was prepared by alternate layer-by-layer (LBL) self-assembly adsorption technique based on the electrostatic force between the opposite charges carried by these two polymers. UV-Vis spectra was used to monitor the LBL process, and the thickness and immobilization amount of each layer were characterized by quartz crystal microbalance (QCM), which showed the formation of nano-scale multilayer structure and linear mass increase dependent on the alternate adsorption cycles. The electrochemical properties of the PEI-Fc/PSS multilayer film modified gold electrode were investigated by cyclic voltammetry. It was observed clearly that the electrochemical properties of this multilayer film were strongly dependent on the layer number and the ferrocene content in PEI-Fc. The electrochemical kinetic was analyzed based on a general model for surface process, and the experimental data fitted well with that evaluated from the above model. This redox polymer showed potential for the construction of reagentless biosensor.