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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. 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

    2016-06-01

    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. PMID:27175794

  4. 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.

  5. 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 PAGESBeta

    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 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

  6. 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.

  7. 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.

  8. Effect of Nanotube Type on the Enhancement of Mechanical Properties of Free-Standing Polymer/Nanotube Composite Films

    NASA Astrophysics Data System (ADS)

    Cadek, M.; Coleman, J. N.; Blond, D.; Fonseca, A.; Nagy, J. B.; Szostak, K.; Béguin, F.; Blau, W. J.

    2003-10-01

    In this work it will be shown that the mechanical reinforcement of polymer composites using carbon nanotubes is dependant on the total surface area of carbon nanotubes dispersed into the polymer matrix. Furthermore, it will be shown that the total length of carbon nanotubes dispersed in the polymer matrix does not have any influence on the mechanical properties. Four differently produced carbon nanotube samples were introduced into a polyvinyl alcohol matrix and it can be reported that the sample with the smallest diameter, thus the nanotube sample with the highest surface area, increased mechanical properties such as tensile modulus by 120% while adding less than 1wt% of carbon nanotubes. Measurements were accomplished on bulk free standing polymer films by tensile testing.

  9. 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

  10. 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.

  11. Directed Assembly of Nanofilled Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Karim, Alamgir

    Facile directed self-assembly (DSA) of multicomponent thin films is important for potential technological applications. This requires a fine control of a complex interplay of processing parameters that need to be properly optimized for different organized structures. This talk will discuss some of our recent success towards realizing tunable DSA of soft matter multicomponent systems involving a dispersion of polymer-grafted nanoparticles in block copolymer or homopolymer matrices. DSA methods for such multicomponent films will be discussed. These include the use of zone-annealing with soft-shear to create highly anisotropic nanoparticle arrays, while direct immersion annealing (DIA) has been used to order nanoparticle filled films by dipping the films into controlled solvent quality solvent mixtures. A recently observed phenomena of confinement driven entropic order and phase segregation of polymer grafted nanoparticles in similar and dissimilar polymer matrices in melt state will be discussed. A high density of nano particles of different types ranging from metallic to inorganic to organic were patterned almost exclusively into channels via topographical soft confinement using entropic forces. Enthalpic interactions between the nanoparticle grafted layer and the polymer matrix could be used as a further handle to tune the directed assembly of the nanoparticles. The phenomena will be discussed in terms of confinement parameters, partition coefficient, free energy gain and entropic versus enthalpic interactions.

  12. n-Type transparent conducting films of small molecule and polymer amine doped single-walled carbon nanotubes.

    PubMed

    Mistry, Kevin S; Larsen, Brian A; Bergeson, Jeremy D; Barnes, Teresa M; Teeter, Glenn; Engtrakul, Chaiwat; Blackburn, Jeffrey L

    2011-05-24

    In this report, we investigate the electrical and optical properties of thin conducting films of SWNTs after treatment with small molecule and polymeric amines. Among those tested, we find hydrazine to be the most effective n-type dopant. We use absorbance, Raman, X-ray photoelectron, and nuclear magnetic resonance spectroscopies on thin conducting films and opaque buckypapers treated with hydrazine to study fundamental properties and spectroscopic signatures of n-type SWNTs and compare them to SWNTs treated with nitric acid, a well-characterized p-type dopant. We find that hydrazine physisorbs to the surface of semiconducting and metallic SWNTs and injects large electron concentrations, raising the Fermi level as much as 0.7 eV above that of intrinsic SWNTs. Hydrazine-treated transparent SWNT films display sheet resistances nearly as low as p-type nitric-acid-treated films at similar optical transmittances, demonstrating their potential for use in photovoltaic devices as low work function transparent electron-collecting electrodes. PMID:21388221

  13. Acid diffusion through polymer films

    NASA Astrophysics Data System (ADS)

    Zhang, P. Linda; Eckert, Andrew R.; Willson, C. Grant; Webber, Stephen E.; Byers, Jeffrey D.

    1997-07-01

    In order to perform 0.2 micrometer processes, one needs to study the diffusion of photoacid generators within the photoresist system, since diffusion during post exposure bake time has an influence on the critical dimension (CD). We have developed a new method to study the diffusion of photoacid generators within a polymer film. This new method is based on monitoring the change of the fluorescence intensity of a pH- sensitive fluorescent dye caused by the reaction with photoacid. A simplified version of this experiment has been conducted by introducing acid vapor to quench the fluorescence intensity of this pH sensor. A thin polymer film is spin cast onto the sensor to create a barrier to the acid diffusion process. During the acid diffusion process, the fluorescence intensity of this pH sensor is measured in situ, using excitation and emission wavelengths at 466 nm and 516 nm, respectively. Fluoresceinamine, the pH sensitive fluorescent dye, is covalently bonded onto the treated quartz substrate to form a single dye layer. Poly(hydroxystyrene) (Mn equals 13k, Tg equals 180 degrees Celsius) in PGMEA (5% - 18% by weight) is spin cast onto this quartz substrate to form films with varying thickness. The soft bake time is 60 seconds at 90 degrees Celsius and a typical film has a thickness of 1.4 micrometers. Trifluoroacetic acid is introduced into a small chamber while the fluorescence from this quartz window is observed. Our study focuses on finding the diffusion constant of the vaporized acid (trifluoroacetic acid) in the poly(hydroxystyrene) polymer film. By applying the Fick's second law, (It - Io)/(I(infinity ) - Io) equals erfc [L/(Dt)1/2] is obtained. The change of fluorescence intensity with respect to the diffusion time is monitored. The above equation is used for the data analysis, where L represents the film thickness and t represents the average time for the acid to diffuse through the film. The diffusion constant is calculated to be at the order of 10

  14. 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. PMID:25066958

  15. Dynamics of polymer thin films and surfaces

    NASA Astrophysics Data System (ADS)

    Fakhraai, Zahra

    2007-12-01

    The dynamics of thin polymer films display many differences from the bulk dynamics. Different modes of motions in polymers are affected by confinement in different ways. The enhancement in the dynamics of some modes of motion can cause anomalies in the glass transition temperature (Tg) of thin films, while other modes of motion such as diffusion can be substantially slowed down due to the confinement effects. In this thesis, different modes of dynamics are probed using different techniques. The interface healing of two identical polymer surfaces is used as a probe of segmental motion in the direction normal to the plane of the films and it is shown that this mode of motion is slowed down at temperatures above bulk glass transition, while the glass transition itself is decreased indicating that the type of motion responsible for the glass transition is enhanced. The glass transition measurements at different cooling rates indicate that this enhancement only happens at temperatures close to or below bulk glass transition temperature and it is not expected to be detected at higher temperatures where the system is in the melt state. It is shown that the sample preparation technique is not a factor in observing this enhanced dynamics, while the existence of the free surface can be important in observed reductions in the glass transition temperature. The dynamics near the free surface is further studied using a novel nano-deformation technique, and it is shown that the dynamics near the free surface is in fact enhanced compared to the bulk dynamics and this enhancement is increased as the temperature is decreased further below Tg. It is also shown that this mode of relaxation is much different from the bulk modes of relaxations, and a direct relationship between this enhanced motion and Tg reduction in thin films can be established. The results presented in this thesis can lead to a possible universal picture that can resolve the behavior of different modes of motions in

  16. 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.

  17. 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.

  18. Fabrication and characterization of p+-i-p+ type organic thin film transistors with electrodes of highly doped polymer

    NASA Astrophysics Data System (ADS)

    Tadaki, Daisuke; Ma, Teng; Zhang, Jinyu; Iino, Shohei; Hirano-Iwata, Ayumi; Kimura, Yasuo; Rosenberg, Richard A.; Niwano, Michio

    2016-04-01

    Organic thin film transistors (OTFTs) have been explored because of their advantageous features such as light-weight, flexible, and large-area. For more practical application of organic electronic devices, it is very important to realize OTFTs that are composed only of organic materials. In this paper, we have fabricated p+-i-p+ type of OTFTs in which an intrinsic (i) regioregular poly (3-hexylthiophene) (P3HT) layer is used as the active layer and highly doped p-type (p+) P3HT is used as the source and drain electrodes. The 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) was used as the p-type dopant. A fabricating method of p+-i-p+ OTFTs has been developed by using SiO2 and aluminum films as capping layers for micro-scaled patterning of the p+-P3HT electrodes. The characteristics of the OTFTs were examined using the photoelectron spectroscopy and electrical measurements. We demonstrated that the fabricated p+-i-p+ OTFTs work with carrier injection through a built-in potential at p+/i interfaces. We found that the p+-i-p+ OTFTs exhibit better FET characteristics than the conventional P3HT-OTFT with metal (Au) electrodes, indicating that the influence of a carrier injection barrier at the interface between the electrode and the active layer was suppressed by replacing the metal electrodes with p+-P3HT layers.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Structures and Elastic Moduli of Polymer Nanocomposite Thin Films

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  4. Polymer-assisted deposition of films

    DOEpatents

    McCleskey, Thomas M.; Burrell; Anthony K.; Jia; Quanxi; Lin; Yuan

    2009-10-20

    A polymer assisted deposition process for deposition of metal oxide films and the like is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films and the like. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  5. Polymer-assisted deposition of films

    DOEpatents

    McCleskey, Thomas M.; Burrell, Anthony K.; Jia, Quanxi; Lin, Yuan

    2008-04-29

    A polymer assisted deposition process for deposition of metal oxide films is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  6. Polymer-assisted deposition of films

    DOEpatents

    McCleskey,Thomas M.; Burrell,Anthony K.; Jia,Quanxi; Lin,Yuan

    2012-02-28

    A polymer assisted deposition process for deposition of metal nitride films and the like is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures under a suitable atmosphere to yield metal nitride films and the like. Such films can be conformal on a variety of substrates including non-planar substrates. In some instances, the films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  7. Supramolecular structure of electroactive polymer thin films

    NASA Astrophysics Data System (ADS)

    Kornilov, V. M.; Lachinov, A. N.; Karamov, D. D.; Nabiullin, I. R.; Kul'velis, Yu. V.

    2016-05-01

    This paper presents the results of an experimental investigation of the supramolecular structure of polydiphenylenephthalide thin films that exhibit effects of resistive switching. The supramolecular structure of the polymer has been investigated using small-angle neutron scattering in conjunction with atomic force microscopy. It has been found that the internal structure of polymer films consists of structural elements in the form of spheroids. The sizes of the structural elements, which were obtained from the neutron scattering data and analysis of the atomic force microscopy images, correlate well with each other. A model of the formation of polymer layers has been proposed. The observed structural elements in polymer films are formed due to the association of macromolecules in the initial polymer solution.

  8. Effect of absorbents on water vapor transmission of free and applied polymer films.

    PubMed

    Amann, A H

    1976-04-01

    The influence of different types of absorbents on moisture transmission through free (cast films) and applied (coated tablets) polymer films was investigated. In free film studies, lubricated granulations were considered to be the absorbent. The compressed tablet was considered to be the absorbent in applied film studies. The results suggested that, using the same film formulation and film thickness in all cases, the polymer film reduced moisture absorption to the same degree, independent of the absorbent used, suggesting a constant moisture permeation. The results of the free film studies also simulated those of the applied films, allowing the correlation of the data. PMID:1271250

  9. 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.

  10. 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.

  11. Contact cleaning of polymer film solar reflectors

    NASA Astrophysics Data System (ADS)

    Sansom, Christopher; Fernández-García, Aránzazu; Sutter, Florian; Almond, Heather; King, Peter

    2016-05-01

    This paper describes the accelerated ageing of polymer film reflecting surfaces under the conditions to be found during contact cleaning of Concentrating Solar Power (CSP) collectors in the presence of dust and sand particles. In these situations, contact cleaning using brushes and water is required to clean the reflecting surfaces. Whilst suitable for glass reflectors, this paper discusses the effects of existing cleaning processes on the optical and visual properties of polymer film surfaces, and then describes the development of a more benign but effective contact cleaning process for cleaning polymer reflectors. The effects of a range of cleaning brushes are discussed, with and without the presence of water, in the presence of sand and dust particles from selected representative locations. Reflectance measurements and visual inspection shows that a soft cleaning brush with a small amount of water can clean polymer film reflecting surfaces without inflicting surface damage or reducing specular reflectance.

  12. Influence of the linkage type between the polymer backbone and side groups on the surface segregation of methyl groups during film formation.

    PubMed

    Zhang, Yizhi; Fan, Hao; Wang, Yuping; Zuo, Biao; Zhang, Wei; Wang, Shunli; Wang, Xinping

    2015-12-21

    Although poly(vinyl acetate) (PVAc) differs from poly(methyl acrylate) (PMA) only in the reversed position of the ester group, a large difference in the concentration dependence of the casting solution on the corresponding surface structure of the cast films of PVAc, PMA and poly(methyl methacrylate) (PMMA) was observed. The hydrophobicity of both PMA and PMMA films increased with increasing concentration of the corresponding polymer solution, whereas cast PVAc films showed the reverse trend. The surface structure of the cast films prepared with different concentrations of the casting solution, characterized by sum frequency generation (SFG) vibrational spectra, showed that the order of the methylene groups increased while that of the acetyl methyl group decreased on the surface of cast PVAc film with increasing concentration of casting solution. However, the order of the ester methyl group increased and that of methylene groups did not change for cast PMA films with increasing concentration of casting solution. The cast PMMA film showed a reverse trend compared with the corresponding PMA film. It is apparent that well-ordered ester or acetyl methyl groups on the surface, which are oriented away from the polymer film, rather than methylene groups, play an important role in determining surface hydrophobicity, as the latter shield the OC[double bond, length as m-dash]O groups of PVAc, PMA and PMMA film surfaces from being exposed, resulting in low surface free energy. The reason for this difference is attributed to the relatively low energy for ester methyl group reorientation, an ester group structure nearer to the trans state and more regular local configuration of segments in concentrated solutions of PMA and PMMA compared to that of PVAc. PMID:26415634

  13. 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

  14. 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

  15. 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.

  16. Electrochemical formation of a composite polymer-aluminum oxide film

    NASA Astrophysics Data System (ADS)

    Runge-Marchese, Jude Mary

    1997-10-01

    The formation of polymer films through electrochemical techniques utilizing electrolytes which include conductive polymer is of great interest to the coatings and electronics industries as a means for creating electrically conductive and corrosion resistant finishes. One of these polymers, polyamino-benzene (polyaniline), has been studied for this purpose for over ten years. This material undergoes an insulator-to-metal transition upon doping with protonic acids in an acid/base type reaction. Review of prior studies dealing with polyaniline and working knowledge of aluminum anodization has led to the development of a unique process whereby composite polymer-aluminum oxide films are formed. The basis for the process is a modification of the anodizing electrolyte which results in the codeposition of polyaniline during aluminum anodization. A second process, which incorporates electrochemical sealing of the anodic layer with polyaniline was also developed. The formation of these composite films is documented through experimental processing, and characterized by way of scientific analysis and engineering tests. Analysis results revealed the formation of unique dual phase anodic films with fine microstructures which exhibited full intrusion of the columnar aluminum oxide structure with polyaniline, indicating the polymer was deposited as the metal oxidation proceeded. An aromatic amine derivative of polyaniline with aluminum sulfate was determined to be the reaction product within the aluminum oxide phase of the codeposited films. Scientific characterization determined the codeposition process yields completely chemically and metallurgically bound composite films. Engineering studies determined the films, obtained through a single step, exhibited superior wear and corrosion resistance to conventionally anodized and sealed films processed through two steps, demonstrating the increased manufacturing process efficiency that can be realized with the modification of the

  17. Electrically conducting novel polymer films containing pi-stacks

    NASA Astrophysics Data System (ADS)

    Duan, Robert Gang

    1997-12-01

    The primary focus of this thesis is to expand our knowledge of ion radicals of π-dimers and π- stacks in solutions and apply these insights in the development and understanding of new electrically conducting polymers. Two types of the conducting polymers were investigated. The first is the conducting polymer composites embedded with π-stacks of ion radicals. Flexible and air stable n-typed conducting thin films were prepared from imide/poly(vinyl alcohol) aqueous solutions. Conducting thin films of terthiophene/poly(methyl methacrylate) were cast from hexafluoro-2-propanol. Effects of casting conditions on the morphology and conductivity of the films were investigated. These films were fully characterized by UV- vis, NIR, IR, XRD, SEM and ESR. In the second type of conducting polymer system, PAMAM dendrimers generation 1 through 5 were peripherally modified with cationically substituted naphthalene diimide anion radicals. NMR, UV, IR, CV and Elemental Analysis were used to characterize modified dendrimers. Reduction with sodium dithionite in solution showed anion radicals were aggregated into π-dimers and π- stacks. Formamide was used to cast conducting dendrimer films. ESCA, SEM and optical microscope were used to study the composition and the morphology of the films. XRD showed complete amorphous nature of these films. NIR revealed that the π-stack aggregation depend strongly on the casting temperature and the degree of reduction. Four- probe co-liner conductivity of the films is on the order of 10-2 to 10-1/ S/ cm-1. ESR and conductivity measurements also revealed the isotropic nature of the conductivity. Conductivity/humidity relationship was discovered by accidental breathing over the films. Using a home-made controlled humidity device and PACERTM hygrometer, the conductivity of the films can be varied quickly and reversibly within two orders of a magnitude. This phenomenon was probed with NIR, XRD and quartz crystal microbalance techniques. These

  18. Patterned cholesteric liquid crystal polymer film.

    PubMed

    Hsu, Wei-Liang; Ma, Ji; Myhre, Graham; Balakrishnan, Kaushik; Pau, Stanley

    2013-02-01

    Herein, the ability to create arbitrarily patterned circular polarized optical devices is demonstrated by using cholesteric liquid crystal polymer. Photoalignment with polarized ultraviolet light is utilized to create aligned cholesteric liquid crystal films. Two different methods, thermal annealing and solvent rinse, are utilized for patterning cholesteric liquid crystal films over large areas. The patterned cholesteric liquid crystal films are measured using a Mueller matrix imaging polarimeter, and the polarization properties, including depolarization index, circular diattenuation (CD), and circular retardance are derived. Patterned nonlinearly polarized optical devices can be fabricated with feature sizes as small as 20 μm with a CD of 0.812±0.015. Circular polarizing filters based on polymer cholesteric liquid crystal films have applications in three-dimensional displays, medical imaging, polarimetry, and interferometry. PMID:23456060

  19. 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.

  20. Oriented thin films of perylenetetracarboxylic diimide on frictiontransferred polymer films

    NASA Astrophysics Data System (ADS)

    Tanigaki, Nobutaka; Heck, Claire; Mizokuro, Toshiko

    Perylenetetracarboxylic diimide (PTCDI) is a promising material for application in organic electronics. In this study we report on the preparation of oriented thin films of PTCDI on the surface of oriented polymer substrates, which were prepared by friction transfer method. Two polymers, poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene) (PPP) were used as the orienting substrate for PTCDI for comparison studies. Characterization by polarized UV-vis absorption shows that the orienting ability of PPP is larger than that of PTFE substrate. Furthermore, polarization-sensitive photoelectric conversion devices were fabricated by using the oriented PTCDI thin film on the PPP substrate.

  1. 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

  2. Deformation propagation in responsive polymer network films

    NASA Astrophysics Data System (ADS)

    Ghosh, Surya K.; Cherstvy, Andrey G.; Metzler, Ralf

    2014-08-01

    We study the elastic deformations in a cross-linked polymer network film triggered by the binding of submicron particles with a sticky surface, mimicking the interactions of viral pathogens with thin films of stimulus-responsive polymeric materials such as hydrogels. From extensive Langevin Dynamics simulations we quantify how far the network deformations propagate depending on the elasticity parameters of the network and the adhesion strength of the particles. We examine the dynamics of the collective area shrinkage of the network and obtain some simple relations for the associated characteristic decay lengths. A detailed analysis elucidates how the elastic energy of the network is distributed between stretching and compression modes in response to the particle binding. We also examine the force-distance curves of the repulsion or attraction interactions for a pair of sticky particles in the polymer network film as a function of the particle-particle separation. The results of this computational study provide new insight into collective phenomena in soft polymer network films and may, in particular, be applied to applications for visual detection of pathogens such as viruses via a macroscopic response of thin films of cross-linked hydrogels.

  3. 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).

  4. 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.

  5. 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)

  6. Simultaneous Vapor Deposition and Phase Separation of Polymer Films

    NASA Astrophysics Data System (ADS)

    Tao, Ran; Anthamatten, Mitchell

    2012-02-01

    Initiated chemical vapor deposition (iCVD) is a solventless, free radical technique used predominately to deposit homogeneous films of linear and crosslinked polymers directly from gas phase feeds. The major goal of this research is to force and arrest phase separation of deposited species by co-depositing non-reactive molecules (porogens) with reactive monomers and crosslinkers. We introduce these species during iCVD to force and quench polymer induced phase separation (PIPS) during film growth as a step toward tunable pore-size, density, and morphology. Polymerization, crosslinking and PIPS are intended to occur simultaneously on the substrate, resulting in a vitrified microstructure. Cahn-Hilliard theory predicts that the length scale of phase separation depends on the polymer-porogen interaction energy, the polymerization rate and the species' mobility. A series of films were grown by varying deposition rate, porogen type, and reagent flowrates. Crosslinkers were introduced to limit the growth of phase separated domains and to provide mechanical support during porogen removal. To elucidate how phase separation competes with polymerization and film growth, deposited films were studied using a combination of electron microscopy, profilometry and spectroscopic techniques.

  7. 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.

  8. Drying of polymer films: study of demixing phenomena

    NASA Astrophysics Data System (ADS)

    Fichot, Julie; Heyd, Rodolphe; Saboungi, Marie-Louise; Josserend, Christophe; Combard, Emilie; Tranchant, Jean Francois

    2011-03-01

    Understanding the mechanisms that control the stability of polymeric films is important in beauty care. We have prepared films starting from a water-soluble organic polymer, a preservative and water. We study the drying of these films as a function of several physicochemical parameters that control their interfaces such as temperature, humidity and the nature of the support. The viscoelastic properties of the solutions before spreading out are analyzed with a rheometer in order to adjust the temperature. The topography of the films is observed by optical microscopy and the evolution of the drying is determined with a precision gravimetric balance. The behavior of the films on a nanometric scale is followed by AFM. During the drying process, droplets appear on the surface of the film, made up of water surrounded by a shell of preservative. As the films dries, the water evaporates from the droplets and the preservative spreads on the surface of the film, leading to the formation of craters on the surface of the dried film. The dimensions and numbers of the craters depend strongly on the type and concentration of the preservative employed.

  9. Nanoscale lubricating film formation by linear polymer in aqueous solution

    NASA Astrophysics Data System (ADS)

    Liu, Shuhai; Guo, Dan; Xie, Guoxin

    2012-11-01

    Film-forming properties of polymer in aqueous solution flowing through a nanogap have been investigated by using a thin film interferometry. The film properties of linear polymer in aqueous solution flowing through a confined nanogap depend on the ratio of water film thickness to averaged radius of polymer chains H0/RPolymer. It was found that the lubrication film thickness of linear polymer in aqueous solution decreases as the polymer molecular weight increasing when H0/RPolymer < 2 ˜ 3. A new lubrication map was proposed, which includes the lubrication regime of weak confinement influence, the lubrication regime of strong confinement influence (LRSCI), and the transition regime of confinement influence. It is very difficult to increase the lubrication film thickness using the higher molecule weight in the LRSCI regime. The lubrication mechanism inferred from our experimental results may help to better understand the dynamic film properties of linear polymer in aqueous solution flowing through a nanogap.

  10. 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.

  11. Germanium films by polymer-assisted deposition

    SciTech Connect

    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.

  12. 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)

  13. Fluorescence Recovery after Photobleaching in Confined Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Gray, Laura A. G.; Brangwynne, Clifford P.; Priestley, Rodney D.

    Over the past twenty years many studies have shown a reduction in the glass transition temperature (Tg) of thin polymer films confined on the nanoscale when supported on non-attractive substrates or free-standing. The depth dependence of Tg has been measured using thin layers of fluorescently tagged polymer to localize the dye within a larger polymer film stack, revealing a decrease in local Tg tens of nanometers into the film. These results have been explained by the propagation of enhanced mobility from the free-surface into the polymer film. Fewer direct measurements of molecular mobility have been made in confined polymer systems. Here, we present the results of fluorescence recovery after photobleaching (FRAP) experiments investigating the mobility of fluorescently doped and labeled methacrylate-based polymers confined in thin film geometries. Bleaching and recovery was monitored using a laser-scanning confocal microscope that enabled us to bleach arbitrary micron-sized shapes to monitor diffusion in polymer melts.

  14. Nanomechanical study of thin film nanocomposite and PVD thin films on polymer substrates for optical applications

    NASA Astrophysics Data System (ADS)

    Moghal, Jonathan; Bird, Andrew; Harris, Adrian H.; Beake, Ben D.; Gardener, Martin; Wakefield, Gareth

    2013-12-01

    The mechanical properties of ultrathin (<120 nm) films differ substantially from the bulk properties of the material and are also strongly substrate dependent. We compare the properties of two differing film systems; a high particle loading nanocomposite of silica and a multiple layer physical vapour deposition (PVD) coating by nanoindentation, nano-scratch and nano-impact followed by structural analysis. The work is undertaken on hardcoated polymer substrates and uses two types of anti-reflection coatings as test systems. The nanocomposite film comprises of a high (>50%) loading of silica nanoparticles in an inorganic binder, which demonstrates significant flex and elastic recovery whereas PVD films are subject to brittle failure even at low applied loads. Failure of the nanocomposite film, with the exception of minor plastic deformation, does not occur until the underlying substrate fails. Although the PVD film has a greater hardness than the nanocomposite, failure occurs at lower loads due to a number of toughness reducing factors including reduced modulus, modulus mismatch with the substrate and film thickness. The resistance of ultrathin films to external mechanical stresses is therefore related to a number of factors and not simply to film hardness, the most important of which are film structure and film mechanical matching to the substrate.

  15. 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

    2015-06-01

    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. PMID:25900070

  16. 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.

  17. 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.

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

    DOEpatents

    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.

  19. Main chain type benzoxaine polymers for high performance applications

    NASA Astrophysics Data System (ADS)

    Chernykh, Andrey

    A new polymer with benzoxazine group in the main chain has been synthesized through the Mannich condensation of a difunctional phenol, formaldehyde and a diamine. Obtained polymer has weight average molecular weight of approximately 10,000 Da and a moderately broad polydispersity index. The new polymer is used to manufacturer self-supporting film of thermosetting resins. Aiming to obtain higher molecular weight, click chemistry approach has been applied to synthesize linear benzoxazine polymers. Three types of polymers have been prepared from dipropargyl- and novel diazide-functionalized benzoxazine monomers, showing a tremendous flexibility for applying click reaction to obtain various polymer architectures. The weight average molecular weight is estimated to be in the range from 50,000 to 100,000 Da which is significantly higher than the benzoxazine polymers which have been chain extended via Mannich reaction. Further developing approach of polycondensation of the monomers containing ozaxine rings, the oxidative coupling approach has been utilized in order to couple benzoxazines with terminal acetylene groups. A model benzoxazine compound containing diacetylene linkage exhibits unexpectedly low exothermic peak with the onset around 140°C, which is significantly lower than the temperature of conventional benzoxazine polymerization. The initial model studies have been made in order to understand this phenomenon and preliminary explanation is given. Extending this pathway to the difunctional propargyl- and ethynyl-functionalized benzoxazine monomers, a series of novel benzoxazine polymers containing diacetylene groups in the main chain have been synthesized. The weight average molecular weight of the polymers is achieved to be up to 50,000 Da. The effect of diacetylene moiety on the benzoxazine crosslinking behavior is even more pronounced for the obtained linear polymers showing exothermic peak with the onset at around 125°C and its maximum at 185°C. Upon

  20. Slow-Positron Generator For Studying Polymer Films

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; St. Clair, Terry L.; Eftekhari, Abe

    1992-01-01

    Aspects of molecular structures probed by positron-annihilation spectroscopy (PAS). Slow-positron-beam generator suitable for PAS measurements in thin polymer films. Includes Na22 source of positrons and two moderators made of well-annealed tungsten foil. With proper choice of voltage, positrons emitted by inward-facing surfaces of moderators made to stop in polymer films tested.

  1. 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.

  2. Selective Template Wetting Routes to Hierarchical Polymer Films: Polymer Nanotubes from Phase-Separated Films via Solvent Annealing.

    PubMed

    Ko, Hao-Wen; Cheng, Ming-Hsiang; Chi, Mu-Huan; Chang, Chun-Wei; Chen, Jiun-Tai

    2016-03-01

    We demonstrate a novel wetting method to prepare hierarchical polymer films with polymer nanotubes on selective regions. This strategy is based on the selective wetting abilities of polymer chains, annealed in different solvent vapors, into the nanopores of porous templates. Phase-separated films of polystyrene (PS) and poly(methyl methacrylate) (PMMA), two commonly used polymers, are prepared as a model system. After anodic aluminum oxide (AAO) templates are placed on the films, the samples are annealed in vapors of acetic acid, in which the PMMA chains are swollen and wet the nanopores of the AAO templates selectively. As a result, hierarchical polymer films containing PMMA nanotubes can be obtained after the AAO templates are removed. The distribution of the PMMA nanotubes of the hierarchical polymer films can also be controlled by changing the compositions of the polymer blends. This work not only presents a novel method to fabricate hierarchical polymer films with polymer nanotubes on selective regions, but also gives a deeper understanding in the selective wetting ability of polymer chains in solvent vapors. PMID:26831764

  3. Nanoparticles for suppression of dewetting of thin polymer films for use in chemical sensors.

    SciTech Connect

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

    2004-08-01

    Addition of fullerenes (C60 or buckyballs) to a linear polymer has been found to eliminate dewetting when a thin (?50 nm) film is exposed to solvent vapor. Based on neutron reflectivity measurements, it is found that the fullerenes form a coherent layer approximately 2 nm thick at the substrate--polymer film interface during the spin-coating process. The thickness and relative fullerene concentration (?29 vol%) is not altered during solvent vapor annealing and it is thought this layer forms a solid-like buffer shielding the adverse van der Waals forces promoted by the underlying substrate. Several polymer films produced by spin- or spray-coating were tested on both silicon wafers and live surface acoustic wave sensors demonstrating fullerenes stabilize many different polymer types, prepared by different procedures and on various surfaces. Further, the fullerenes drastically improve sensor performance since dewetted films produce a sensor that is effectively inoperable.

  4. Precursors for the polymer-assisted deposition of films

    DOEpatents

    McCleskey, Thomas M.; Burrell, Anthony K.; Jia, Quanxi; Lin, Yuan

    2013-09-10

    A polymer assisted deposition process for deposition of metal oxide films is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  5. 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.

  6. Metalizable Polymer Thin Films in Supercritical Carbon Dioxide

    SciTech Connect

    Koga,T.; Jerome, J.; Rafailovich, M.; Sokolov, J.; Gordon, C.

    2005-01-01

    We report an environmentally 'green' method to improve adhesion at a polymer/metal interface by using supercritical carbon dioxide (scCO 2 ). Spun-cast polystyrene (PS) and poly(methyl methacrylate) (PMMA) thin films on cleaned Si wafers were used for this study. Film thicknesses of both polymer films were prepared in the range of 100 Angstroms to 1600 Angstroms. We exposed the films to scCO 2 in the pressure-temperature (P-T) range corresponding to the density-fluctuation ridge, where the excess swelling of both polymer films occurred, and then froze the swollen structures by quick evaporation of CO2. A chromium (Cr) layer with film thickness of 300-400 Angstroms was deposited onto the exposed film by using an E-beam evaporator. X-ray reflectivity (XR) measurements showed that the interfacial width between the Cr and exposed polymer layers increased by a factor of about two compared with that without exposure to scCO 2. In addition, the large interfacial broadening was found to occur irrespective of the thickness of both polymer films. After the XR measurements, the dewetting structures of the PS/Cr films induced by additional annealing were characterized by using atomic force microscopy, showing improved surface morphology in the exposed films. Contact angle measurements showed that a decrease in interfacial tension with exposure to scCO 2 accompanied the increase in interfacial width.

  7. 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.

  8. Slip effects in polymer thin films.

    PubMed

    Bäumchen, O; Jacobs, K

    2010-01-27

    Probing the fluid dynamics of thin films is an excellent tool for studying the solid/liquid boundary condition. There is no need for external stimulation or pumping of the liquid, due to the fact that the dewetting process, an internal mechanism, acts as a driving force for liquid flow. Viscous dissipation, within the liquid, and slippage balance interfacial forces. Thus, friction at the solid/liquid interface plays a key role towards the flow dynamics of the liquid. Probing the temporal and spatial evolution of growing holes or retracting straight fronts gives, in combination with theoretical models, information on the liquid flow field and, especially, the boundary condition at the interface. We review the basic models and experimental results obtained during the last several years with exclusive regard to polymers as ideal model liquids for fluid flow. Moreover, concepts that aim to explain slippage on the molecular scale are summarized and discussed. PMID:21386275

  9. New paradigm for stabilization of liquid polymer films on solids

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Jiang, Naisheng; Wang, Jiaxun; di, Xiaoyu; Cheung, Justin; Endoh, Maya

    2015-03-01

    We report that wetting/dewetting behavior of liquid polymer films on solids can be controlled by nanoscale architectures of polymer chains irreversibly adsorbed on the impenetrable surfaces. Monodisperse polystyrene (PS) ultrathin films (20 nm in thickness) with different molecular weights on silicon (Si) substrates with a natural amorphous Si dioxide layer were used as models. The PS thin films were annealed at high temperatures at T>Tg (Tg is the bulk glass transition temperature) for several days, and the surface structures were studied by using optical and atomic force microscopes. At the same time, the annealed PS films were further leached with a good solvent and the residue films (i.e., irreversibly adsorbed layers) were characterized by x-ray reflectivity. The experimental data reveals a strong correlation between the conformations of the adsorbed polymer chains and the stability of the liquid films on top. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  10. 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.

  11. Nonfouling tunable βCD dextran polymer films for protein applications.

    PubMed

    Städe, Lars W; Nielsen, Thorbjørn T; Duroux, Laurent; Hinge, Mogens; Shimizu, Kyoko; Gurevich, Leonid; Kristensen, Peter K; Wingren, Christer; Larsen, Kim L

    2015-02-25

    Polymeric β-cyclodextrin (βCD) films tunable with respect to thickness and βCD content were prepared in order to develop a suitable platform, allowing for inclusion of nonpolar guest molecules in the βCD cavity, while suppressing nonspecific protein adsorption. The βCD films were synthesized from linear βCD dextran polymers, and grafted onto silicon oxide surfaces by "click" chemistry. Topographic and morphological characteristics are controllable by reaction conditions and polymer type, with average film heights from 2.5 to 12.5 nm. Reversible introduction of electrostatic charges in the βCD dextran by complex formation with 1-adamantanecarboxylic acid prior to surface grafting resulted in a thinner and denser film, presumably by decompaction of the polymers. Total internal reflection fluorescence spectroscopy (TIRF) was employed to evaluate the accessibility of βCD cavities to the fluorescent probe 2-anilinonaphthalene-6-sulfonic acid. Only a minor fraction of the βCD cavities was accessible in the thicker and less dense films; however, accessibility was largely improved with increased ionic strength using NaCl up to 1 M. Antifouling properties of the βCD dextran polymer films were assessed by TIRF real-time monitoring, using bovine serum albumin as a model protein, and showed a 5- to 10-fold reduction in nonspecific adsorption as compared to a bare quartz surface with the degree of reduction reflecting film thickness and interfacial polymer density. PMID:25639169

  12. Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

    PubMed

    Cao, Zi-Quan; Wang, Guo-Jie

    2016-06-01

    Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here. PMID:27153184

  13. Dispersing nanoparticles in a polymer film via solvent evaporation

    DOE PAGESBeta

    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

  14. 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.

  15. 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.

  16. 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.

  17. Atomic-force microscopy of submicron films of electroactive polymer

    NASA Astrophysics Data System (ADS)

    Karamov, D. D.; Kornilov, V. M.; Lachinov, A. N.; Kraikin, V. A.; Ionova, I. A.

    2016-07-01

    Atomic-force microscopy is used to study the supramolecular structure of submicron films of electroactive thermally stable polymer (polydiphenylenephthalide (PDP)). It has been demonstrated that PDP films produced using centrifuging are solid homogeneous films with thicknesses down to several nanometers, which correspond to two or three monomolecular layers. The film volume is structurized at thicknesses greater than 100 nm. The study of the rheological properties of solutions used for film production yields a crossover point that separates the domains of strongly diluted and semidiluted solutions. A transition from the globular structure to the associate structure is observed in films that are produced using solutions with a boundary concentration. A model of the formation of polymer film that involves the presence of associates in the original solution is discussed.

  18. 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.

  19. In situ polarization of polymer films in microsensors

    NASA Astrophysics Data System (ADS)

    Kranz, M.; Allen, M. G.; Hudson, T.

    2012-04-01

    Electret and polymer piezoelectric films have been previously integrated into Micro Electro Mechanical System (MEMS) acoustic sensors and energy harvesters. Common techniques employed in MEMS polymer integration include corona discharge [1] and backlighted thyratron [2], followed by macro-scale assembly of the polymer into the micro device. In contrast, this paper reports a method for post-fabrication in-situ polarization of polymer films embedded within the MEMS device itself. The method utilizes microplasma discharges with self-aligned charging grids integrated within the device to charge fluoropolymer films in a fashion similar to the common corona discharge technique. This in-situ approach enables the integration of uncharged polymer films into MEMS and subsequent post-fabrication and post-packaging polarization, simultaneously enabling the formation of buried or encapsulated electrets as well as eliminating the need to restrict fabrication and packaging processes that might otherwise discharge pre-charged materials. Using the in situ approach, a microscale charging grid structure is fabricated and suspended a short distance above the polymer film. After fabrication of the charging grid, standard microfabrication steps are performed to build MEMS sensors. After completing the entire fabrication and packaging flow, the polarization process is performed. When energized by a high voltage, the sharp metal edges of the charging grid lead to high dielectric fields that ionize the air in the gap and force electric charge onto the polymer surface. This paper presents modeling and results for this in situ polarization process.

  20. 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.

  1. Rapid synthesis of flexible conductive polymer nanocomposite films.

    PubMed

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

    2015-03-27

    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  × 10(4) S cm(-1)), even during repetitive bending. PMID:25736387

  2. Stability of Grafted Polymer Nanoscale Films toward Gamma Irradiation.

    PubMed

    Borodinov, Nikolay; Giammarco, James; Patel, Neil; Agarwal, Anuradha; O'Donnell, Katie R; Kucera, Courtney J; Jacobsohn, Luiz G; Luzinov, Igor

    2015-09-01

    The present article focuses on the influence of gamma irradiation on nanoscale polymer grafted films and explores avenues for improvements in their stability toward the ionizing radiation. In terms of applications, we concentrate on enrichment polymer layers (EPLs), which are polymer thin films employed in sensor devices for the detection of chemical and biological substances. Specifically, we have studied the influence of gamma irradiation on nanoscale poly(glycidyl methacrylate) (PGMA) grafted EPL films. First, it was determined that a significant level of cross-linking was caused by irradiation in pure PGMA films. The cross-linking is accompanied by the formation of conjugated ester, carbon double bonds, hydroxyl groups, ketone carbonyls, and the elimination of epoxy groups as determined by FTIR. Polystyrene, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, dimethylphenylsilanol, BaF2, and gold nanoparticles were incorporated into the films and were found to mitigate different aspects of the radiation damage. PMID:26259102

  3. The total chemical synthesis of polymer/graphene nanocomposite films.

    PubMed

    Salvatierra, Rodrigo V; Cava, Carlos E; Roman, Lucimara S; Oliveira, Marcela M; Zarbin, Aldo J G

    2016-01-28

    A versatile and room temperature synthesis of thin films of polymer/graphene is reported. Drastically differing from other methods, not only the polymer but also the graphene are completely built from their simplest monomers (thiophene and benzene) in a one-pot polymerization reaction at a liquid-liquid interface. The materials were characterized and electronic properties are presented. PMID:26658554

  4. 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.

  5. 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

  6. New interpenetrating network type siloxane polymer electrolyte.

    SciTech Connect

    Oh, B.; Hyung, Y.-E.; Vissers, D. R.; Amine, K.; Chemical Engineering

    2002-11-01

    An interpenetrating network (IPN), comb-type, siloxane-based solid polymer electrolyte solid polymer electrolyte was prepared and its electrochemical properties were evaluated. The cross-linking reaction conditions were established from accelerated rate calorimetry studies. An IPN solid ploymer electrolyte with 60 wt % of the comb-shaped siloxane showed an ionic conductivity of greater than 5x10{sup -4} S/cm at 37 C, with a wide electrochemical stability window of up to 4.5 V vs. lithium. A Li metal/solid polymer electrolyte/LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cell showed promising discharge capacities above 130 mAh/g and good cycling performance.

  7. 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.

  8. Improved morphology in electrochemically grown conducting polymer films

    SciTech Connect

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

    1990-12-31

    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.

  9. Oriented Liquid Crystalline Polymer Semiconductor Films with Large Ordered Domains.

    PubMed

    Xue, Xiao; Chandler, George; Zhang, Xinran; Kline, R Joseph; Fei, Zhuping; Heeney, Martin; Diemer, Peter J; Jurchescu, Oana D; O'Connor, Brendan T

    2015-12-01

    Large strains are applied to liquid crystalline poly(2,5-bis(3-tetradecylthiophen-2yl)thieno(3,2-b)thiophene) (pBTTT) films when held at elevated temperatures resulting in in-plane polymer alignment. We find that the polymer backbone aligns significantly in the direction of strain, and that the films maintain large quasi-domains similar to that found in spun-cast films on hydrophobic surfaces, highlighted by dark-field transmission electron microscopy imaging. The highly strained films also have nanoscale holes consistent with dewetting. Charge transport in the films is then characterized in a transistor configuration, where the field effect mobility is shown to increase in the direction of polymer backbone alignment, and decrease in the transverse direction. The highest saturated field-effect mobility was found to be 1.67 cm(2) V(-1) s(-1), representing one of the highest reported mobilities for this material system. The morphology of the oriented films demonstrated here contrast significantly with previous demonstrations of oriented pBTTT films that form a ribbon-like morphology, opening up opportunities to explore how differences in molecular packing features of oriented films impact charge transport. Results highlight the role of grain boundaries, differences in charge transport along the polymer backbone and π-stacking direction, and structural features that impact the field dependence of charge transport. PMID:26552721

  10. Polymer-assisted aqueous deposition of metal oxide films

    DOEpatents

    Li, DeQuan; Jia, Quanxi

    2003-07-08

    An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

  11. 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.

  12. Deviations from Liquidlike Behavior in Molten Polymer Films at Interfaces

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    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 (Rg) 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, ql,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.

  13. Composite membranes from photochemical synthesis of ultrathin polymer films

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Martin, Charles R.

    1991-07-01

    THERE has recently been a resurgence of interest in synthetic membranes and membrane-based processes1-12. This is motivated by a wide variety of technological applications, such as chemical separations1-7, bioreactors and sensors8,9, energy conversion10,11 and drug-delivery systems12. Many of these technologies require the ability to prepare extremely thin, defect-free synthetic (generally polymeric) films, which are supported on microporous supports to form composite membranes. Here we describe a method for producing composite membranes of this sort that incorporate high-quality polymer films less than 50-nm thick. The method involves interfacial photopolymerization of a thin polymer film on the surface of the microporous substrate. We have been able to use this technique to synthesize a variety of functionalized ultrathin films based on electroactive, photoactive and ion-exchange polymers. We demonstrate the method here with composite membranes that show exceptional gas-transport properties.

  14. Ion-Conducting Polymer Films as Chemical Sensors

    SciTech Connect

    Hughes, R.C.; Patel, S.V.; Pfeifer, K.B.; Yelton, W.G.

    1999-05-03

    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 work on using these films as chemical sensors. We have found that thin films of polymers like polyethyleneoxide (PEO) are very sensitive to low concentrations of volatile organic compounds (VOCS) like common solvents. We will present impedance spectroscopy of PEO films in the frequency range 0.01 Hz to 1 MHz for different concentrations of VOCS. We find that the measurement frequency is important for distinguishing ionic conductivity from the double layer capacitance and parasitic capacitances.

  15. Vacuum deposited polymer/metal films for optical applications

    SciTech Connect

    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.

  16. 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. PMID:23639183

  17. 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.

  18. Patterning Thin Polymer Films by Photodirecting the Marangoni Effect

    NASA Astrophysics Data System (ADS)

    Ellison, Christopher; Kim, Chae Bin; Janes, Dustin; Katzenstein, Joshua

    2014-03-01

    New methodologies for patterning micro- and nano- scale features in polymer thin films are desired because of their high technological relevance to a range of applications, including microelectronics fabrication. A new non-contact strategy for high-speed patterning of arbitrary shapes in polymer films that involves photochemically directing the Marangoni effect will be described. The Marangoni effect drives the formation of thin film topography by causing liquid flow in response to surface energy gradients. In this approach, a topographical pattern can be preprogrammed and stored in a smooth glassy film using light activated chemistry to pattern surface energy gradients. The topography can be later revealed by heating the film to the liquid state without use of a wet or dry etch step, unlike traditional photoresist methods. The use of grafting reactions from small molecule photosensitizers to change the surface energy locally in polymers that do not intrinsically undergo photochemical reactions will also be discussed. Judicious selection of the photosensitizing compound in an otherwise transparent polymer expands the use of this method to more readily available light sources. We believe this methodology will be potentially useful as a facile and ubiquitous patterning technique for many polymers.

  19. Lattice cluster theory for dense, thin polymer films

    NASA Astrophysics Data System (ADS)

    Freed, Karl F.

    2015-04-01

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

  20. 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.

  1. 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

  2. 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).

  3. 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

  4. Polymer crystallization in thin films: morphology and physical properties

    NASA Astrophysics Data System (ADS)

    Kelly, Giovanni; Albert, Julie

    Polymer crystallization has been studied both computationally and experimentally for decades, elucidating many of the mysteries surrounding crystallization kinetics and thermodynamics. However, many unanswered questions remain pertaining to the relationships between crystallization phenomena and material properties needed for specific applications that range from drug delivery and tissue engineering to optical devices and mechanically robust membranes. One of the especially interesting facets of polymer crystallization is the behavior observed when these long chain molecules are spatially confined in thin and ultrathin films. Confined geometry leads to chain configurations, and therefore thermal, mechanical, and optical properties, sometimes far removed from reported bulk values. This project aims to study the phenomena exhibited by linear semi-crystalline polymers in thin films as well as the way in which blending with homopolymers, block copolymers, and novel polymer chain architectures affect morphology, biodegradation, optical, thermal, and mechanical properties.

  5. Sensors employing Functionalized Conducting Polymer Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Tanese, M. C.; Torsi, L.; Cioffi, N.; Sabbatini, L.; Zambonin, P. G.

    2003-12-01

    Functionalized conducting polymers are employed as active layers in sensors with a thin film transistor (TFT) device structure. Such devices can work as multi-parameter sensors with responses that are fast, repeatable and reversible at room temperature. In this work, a strategy is proposed to enhance the chemical selectivity of organic TFT sensors, by selecting active layers that are made of conducting polymers bearing chemically different substituents. A modulation of the devices sensitivity towards analytes such as alcohols and ketones is demonstrated.

  6. Spatial confinement effects on ultrathin semiconducting polymer heterojunction thin films

    SciTech Connect

    Xuejun Zhang; Jenekhe, S.A.

    1996-12-31

    Thin and ultrathin films of electroactive and photoactive polymers are of growing interest for applications in electronic and optoelectronic devices such as thin film transistors, light emitting diodes, solar cells, and xerographic photoreceptors. Although spatial confinement effects on the electronic, optical, optoelectronic, magnetic, and mechanical properties of inorganic semiconductors, metals, oxides, and ceramics are well known and understood, very little is currently known about nanoscale size effects in electroactive and photoactive polymers. Therefore, we recently initiated studies aimed at the understanding of spatial confinement effects on electroactive and photoactive nanostructured polymers and related thin film devices. We have extensively investigated layered nanoscale semiconducting polymer heterojunctions by applying several experimental techniques including photoluminescence, optical absorption, transient absorption, electroluminescence, cyclic voltammetry, and current-voltage measurements. Our findings reveal clear evidence of spatial confinement effects, including: dramatic enhancement of photoconductivity in ultrathin films; enhancement of electroluminescence efficiency and performance characteristics in nanoscale heterojunction devices; observation of novel phenomena in nanoscale devices. These spatial confinement effects in nanostructured semiconducting polymers can be understood in terms of classical charge transport and interfacial processes without invoking quantum size effects.

  7. Air shear driven flow of thin perfluoropolyether polymer films

    NASA Astrophysics Data System (ADS)

    Scarpulla, Michael A.; Mate, C. Mathew; Carter, Malika D.

    2003-02-01

    We have studied the wind driven movement of thin perfluoropolyether (PFPE) polymer films on silicon wafers and CNx overcoats using the blow-off technique. The ease with which a liquid polymer film moves across a surface when sheared is described by a shear mobility χS, which can be interpreted both in terms of continuum flow and in terms of wind driven diffusion. Generally, we find that the movement of PFPE films can be described as a flow process with an effective viscosity, even when the film thickness is smaller than the polymer's diameter of gyration. Only in the special case of sparse coverage of a polymer with neutral end groups is the motion better described by a wind driven diffusion process. The addition of alcohol end groups to the PFPE polymer chain results in strong interactions with the substrate, creating a restricted layer having an effective viscosity an order of magnitude larger than the mobile layer that sits on top of the restricted layer.

  8. Simulation of conductivity of polymer films on metal surface

    NASA Astrophysics Data System (ADS)

    Maksimova, O. G.; Maksimov, A. V.; Baidganov, A. R.

    2015-09-01

    In this paper, protective properties of polymer films are analyzed. The simulation is performed by means of the Monte-Carlo method on the basis of three-dimensional lattice model of polymer system with orientational interactions [1]. Initially, configuration of polymer system is calculated by the Metropolis algorithm taking into account the characteristics of the internal structure (constants of intermolecular interactions etc.), temperature regime and metal quality. Further, for the study of conductivity, the motion of charged particles within the proposed lattice model is investigated on the basis of the calculated configuration. The interaction energy of the oxygen atom with eight neighboring links of polymer chains and electric double layer on the metallic surface is accounted. The direction of movement of charged particles is calculated by the Monte-Carlo method according to the energy advantage of its position. This method allows to calculate the number of charged particles passing through the polymer film and reaching the metal sheet surface. The dependences of conductivity on temperature, film thickness, and distance between molecular layers are obtained. It is shown that there is an optimum density for the given film thickness at which it possesses protective properties. The adequacy of the developed mathematical models and calculated dependences are verified by comparison with laboratory data and production testing.

  9. Swelling Behavior of Ultrathin Polymer Films in Supercritical Ethane

    NASA Astrophysics Data System (ADS)

    Ji, Yuan; Koga, Tadanori; Seo, Young-Soo; Rafailovich, Miriam; Sokolov, Jonathan; Satija, Sushil

    2003-03-01

    Swelling behavior of ultrathin polymer films in supercritical ethane (T_c=32^oC, P_c=4.86MPa) was investigated by using in situ neutron reflectivity (NR). The polymers used in this study were deuterated polystyrene(dPS), deuterated styrene-butadiene copolymer(dSBR), deuterated polymethylmethacrylate(dPMMA), deuterated polybutadiene(dPB) and the films were spun cast on the HF etched cleaned silicon wafers. NR experiments were conducted with the pressure range of 0.1-15 MPa at T=37^oC by using NG7 reflectometer at NIST. As a result, we found that all the polymers used showed anomalous peak in the linear dilation (S_f) curve at P=5.5MPa, i.e., the density fluctuation ridge of ethane while the Sf values for the rubbery polymers were significantly larger (0.8) than those of glassy polymers (0.3). In this presentation, we will also discuss about the universality in the swelling behavior of the polymer thin films in the presence of the supercritical fluids.

  10. New Molecular Theory for Dense, Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Freed, Karl

    2015-03-01

    The development of a molecular theory for dense polymer systems ranks among the most challenging problems in the statistical mechanics of complex matter. These difficulties become compounded when considering the influence of molecular details on thermodynamic properties of thin polymer films, properties deviating from those of the bulk phases. A new theory of dense polymer films is developed as a significant generalization of methods used to devise the lattice cluster theory, an extension of Flory-Huggins theory that include details of monomer structure and short range correlations (neglected in FH theory) and that has successfully been applied to a wide range of polymer systems. 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 implemented in self-consistent theories of polymer adsorption at interfaces. The theory is illustrated by presenting examples of the computed density and chain end profiles for free standing films as a function of bulk density, chain length, temperature, and chain semi-flexibility.

  11. 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. PMID:25340308

  12. Polymer thin film instability from a patterned edge

    NASA Astrophysics Data System (ADS)

    Guo, Yunlong; Zhang, Chuan; Priestley, Rodney D.

    2014-07-01

    Patterning of polymer thin films with nanoscale features is a critical step in nanoscale technologies. Here, we investigate the dewetting process from both a mechanically patterned edge (ME) and a hole edge of a thin polymer film, as a means to assess the influence of residual stresses induced during patterning on stability. At low temperature in which hole nucleation is not observed dewetting can still proceed from the ME. Under conditions in which dewetting proceeded from both edges that from the ME exhibited a crossover to a dramatically reduced dewetting velocity. These results suggest mechanical stress concentrated along the ME remarkably depresses the dewetting process by decreasing the rim growth rate.

  13. 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.

  14. Patterning dewetting in thin polymer films by spatially directed photocrosslinking.

    PubMed

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

    2010-11-15

    In this report we examine the dewetting of spin-cast poly (styrene) films in a confined geometry. We designed a platform for laterally confining PS by photo-patterning crosslinks in spin-coated thin films. Heating the patterned film above the glass transition temperature of PS results in localized dewetting patterns in regions that were not crosslinked, while the crosslinked pattern serves as a rigid barrier that confines the retraction of the uncrosslinked polymer in micron-sized domains. The barriers also provide a favorable surface that the liquid PS wets onto, forming a rim at the boundary of crosslinked and uncrosslinked polymer. The resulting patterns are shown to be dependent on the irradiation and annealing time, the dimensions of the uncrosslinked region and the thickness of the film. PMID:20728089

  15. 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.

  16. Nanowear on polymer films of different architecture.

    PubMed

    Berger, R; Cheng, Y; Förch, R; Gotsmann, B; Gutmann, J S; Pakula, T; Rietzler, U; Schärtl, W; Schmidt, M; Strack, A; Windeln, J; Butt, H-J

    2007-03-13

    In this paper, we describe atomic force microscope (AFM) friction experiments on different polymers. The aim was to analyze the influence of the physical architecture of the polymer on the degree and mode of wear and on the wear mode. Experiments were carried out with (1) linear polystyrene (PS) and cycloolefinic copolymers of ethylene and norbornene, which are stabilized by entanglements, (2) mechanically stretched PS, (3) polyisoprene-b-polystyrene diblock copolymers, with varying composition, (4) brush polymers consisting of a poly(methyl methacrylate) (PMMA) backbone and PS side chains, (5) PMMA and PS brushes grafted from a silicon wafer, (6) plasma-polymerized PS, and (7) chemically cross-linked polycarbonate. For linear polymers, wear depends critically on the orientation of the chains with respect to the scan direction. With increasing cross-link density, wear was reduced and ripple formation was suppressed. The cross-linking density was the dominating material parameter characterizing wear. PMID:17279781

  17. Consequences of Residual Stresses in Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Reiter, Guenter

    2010-03-01

    In our quest for making functional devices smaller, the thickness of polymer films has reached values even smaller than the diameter of the unperturbed molecule. However, despite enormous efforts over the last decade, our understanding of the origin of some puzzling properties of such thin films is still not satisfactory and several peculiar observations remain rather mysterious. In this context, we explore the consequences of the transition from a dilute polymer solution to the glassy state with respect to the properties of polymers in thin films. This transition is likely to result in residual stresses, arising from out-of-equilibrium chain conformations due to rapid solvent loss. Consequently, depending on thermal history and ageing time, such films exhibit significant changes even in the glassy state ^ which we quantify by performing detailed studies of viscoelastic dewetting of thin polystyrene films on solid substrates. We explored relaxation times, residual stresses, and temporal changes of the stability of non-equilibrated thin films as they progress toward stable equilibrium behaviors. To do so, we have focused primarily on times shorter than the reptation time of the polymer. The number of spontaneously nucleated holes per unit area is seen to decrease as the films were aged below the glass transition, showing the meta-stability of the system. The ratio of stress over elastic modulus was found to increase strongly with decreasing film thickness and increasing chain length. Full equilibration of chain conformations required long times comparable to bulk reptation times. However, for chains longer than about 3000 monomers, the residual stress relaxed faster, at a rate independent of chain length. We present some tentative ideas on the relation between these observed atypical mechanical and relaxational behaviors and meta-stable states introduced by sample preparation.

  18. Acoustic resonant spectroscopy for characterization of thin polymer films

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Imaizumi, Takuya; Saka, Masumi

    2006-10-01

    An acoustic resonant spectroscopy technique for measuring the acoustic impedance, ultrasonic velocity, and density of micron-scale polymer films is developed. The method, which is based on spectral analysis, observes the acoustic resonance between water, the film, and a tungsten plate with high acoustic impedance in the frequency range of 20-70MHz. The interface between the film being examined and the plate is vacuum sealed, enabling us to characterize the low-density polyethylene film with acoustic impedances as low as about 1.9MNm-3s and the poly(vinyl chloride) film as thin as about 8μm. The error in the film density measurements is found to be less than 1%, and the validity of the technique is verified.

  19. Simple push coating of polymer thin-film transistors.

    PubMed

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

    2012-01-01

    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. PMID:23132026

  20. 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.

  1. Process optimization of ultrasonic spray coating of polymer films.

    PubMed

    Bose, Sanjukta; Keller, Stephan S; Alstrøm, Tommy S; Boisen, Anja; Almdal, Kristoffer

    2013-06-11

    In this work we have performed a detailed study of the influence of various parameters on spray coating of polymer films. Our aim is to produce polymer films of uniform thickness (500 nm to 1 μm) and low roughness compared to the film thickness. The coatings are characterized with respect to thickness, roughness (profilometer), and morphology (optical microscopy). Polyvinylpyrrolidone (PVP) is used to do a full factorial design of experiments with selected process parameters such as temperature, distance between spray nozzle and substrate, and speed of the spray nozzle. A mathematical model is developed for statistical analysis which identifies the distance between nozzle and substrate as the most significant parameter. Depending on the drying of the sprayed droplets on the substrate, we define two broad regimes, "dry" and "wet". The optimum condition of spraying lies in a narrow window between these two regimes, where we obtain a film of desired quality. Both with increasing nozzle-substrate distance and temperature, the deposition moves from a wet state to a dry regime. Similar results are also achieved for solvents with low boiling points. Finally, we study film formation during spray coating with poly (D,L-lactide) (PDLLA). The results confirm the processing knowledge obtained with PVP and indicate that the observed trends are identical for spraying of other polymer films. PMID:23631433

  2. 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.

  3. Self-assembled multilayers of electroactive polymers: From highly conducting transparent thin films to light emitting diodes

    SciTech Connect

    Fou, A.; Onitsuka, O.; Ferreira, M.

    1995-12-01

    Layer-by-layer self-assembly has recently emerged as a most versatile means of processing conjugated polymers into ultrathin films with unprecedented control over thicknesses and molecular architectures. Multilayer heterostructures have been designed and fabricated from various combinations of conjugated polyions, p-type conducting polymers, sulfonated fullerenes, conjugated polymer precursors, molecular dyes, and a variety of nonconjugated polyions to study properties unique to the supramolecular organizations created. In this paper, we use layer-by-layer self-assembly to fabricate extremely thin, highly conductive films of p-doped conjugated polymers such as polypyrrole and polyaniline. Also complex multilayer heterostructures based on polyphenylene vinylene (PPV) are fabricated to study the intermolecular interactions between the PPV and other components of the film which give rise to {open_quotes}tunable{close_quotes} photoluminescence behavior. Finally, thin film light-emitting devices based on self-assembled PPV active layers are presented.

  4. Development of orodispersible polymer films containing poorly water soluble active pharmaceutical ingredients with focus on different drug loadings and storage stability.

    PubMed

    Woertz, Christina; Kleinebudde, Peter

    2015-09-30

    The aim of this work was the development of orodispersible films containing different film forming polymers with focus on different drug loadings of two poorly water soluble APIs. Furthermore, physical stability of films was examined at two different storage conditions. Loperamide hydrochloride (LPH) and ibuprofen (IBU) were used as model drugs. Hydroxypropyl methylcellulose (HPMC) and three different types of hydroxypropyl cellulose (HPC) were used as film forming polymers. Suspensions were characterized with respect to their viscosity and particle sedimentation and films regarding their content uniformity, thickness, mass and stability. Principal component analysis (PCA) was used to evaluate the correlation between the wet film thickness, dry film thickness, mass of the films, API fraction in the suspension and the viscosity of the suspensions. The viscosity of the suspensions was dependent on the drug load and the polymer fraction but less so on the type of the utilized polymer. A correlation between the wet film thickness, the solid fraction and the mass of the films was established with an increase in mass by increasing the wet film thickness or the solid fraction. Films containing 50 mg IBU/6 cm(2) film led to acceptable films. Storage experiments did not lead to an AV below 15 in all cases after storage for three and six months, attributed to the storage conditions and the quality of the films. Nevertheless, the development and production of flexible and homogeneous films of LPH and IBU was successfully achieved. PMID:26216415

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Lwoya, Baraka; Albert, Julie

    2015-03-01

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

  7. Static properties of equilibrium polymers confined in ultrathin films

    NASA Astrophysics Data System (ADS)

    Cavallo, Anna; Wittmer, Joachim P.; Johner, Albert; Baschnagel, Joerg

    2008-03-01

    The static properties of equilibrium polymer melts confined in ultrathin films are studied by means of Monte Carlo simulations of a lattice model: the bond fluctuation model. In this work we focus on the effects of ultrathin film confinement between two parallel and neutral walls on chain size and molecular weight distribution. We compare our numerical results to analytical calculations by Semenov and Johner [Eur. Phy. J. E, 12, 469 (2003)] who predicted for ultrathin films, logarithmic corrections to the leading mean-field behavior. Our simulation data are compatible with the theoretical results.

  8. 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.

  9. 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.

  10. Naphthalene Tetracarboxydiimide-Based n-Type Polymers with Removable Solubility via Thermally Cleavable Side Chains.

    PubMed

    Hillebrandt, Sabina; Adermann, Torben; Alt, Milan; Schinke, Janusz; Glaser, Tobias; Mankel, Eric; Hernandez-Sosa, Gerardo; Jaegermann, Wolfram; Lemmer, Uli; Pucci, Annemarie; Kowalsky, Wolfgang; Müllen, Klaus; Lovrincic, Robert; Hamburger, Manuel

    2016-02-01

    Multilayer solution-processed devices in organic electronics show the tendency of intermixing of subsequently deposited layers. Here, we synthesize naphthalene tetracarboxydiimide (NDI)-based n-type semiconducting polymers with thermally cleavable side chains which upon removal render the polymer insoluble. Infrared and photoelectron spectroscopy were performed to investigate the pyrolysis process. Characterization of organic field-effect transistors provides insight into charge transport. After the pyrolysis homogeneous films could be produced which are insoluble in the primary solvent. By varying curing temperature and time we show that these process parameters govern the amount of side chains in the film and influence the device performance. PMID:26829619

  11. 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.

  12. Nanomolding the Surface of Polymer Films.

    PubMed

    Foschini, Mauricio; Da Silva, Silésia Fátima Curcino; Tozoni, José Roberto; Zadra-Armond, Raigna Augusta Da Silva; Oliveira, Osvaldo N; Marletta, Alexandre

    2015-08-01

    Slight changes in the experimental procedures of the micro contact printing (ACP) technique are introduced here, which allow for using polymers soluble in distinct solvents to fabricate submicrometric 2D periodic structures. Highly reproducible secondary and tertiary poly(dimethylsiloxane) (PDMS) molds could be produced, as demonstrated in atomic force microscopy images and light diffraction experiments. The replication of tertiary molds with no residues of PDMS demonstrates the feasibility of large-scale production with distinct polymers. The plane wave propagation along the tertiary poly(3,4-ethylenedioxythiophene) with poly(hydrogen 4-styrene sulfonate) molds was simulated with a finite-difference time-domain algorithm. A strong wave propagation was observed in the region containing the structures acting as a wave guide, in agreement with the results from the experimental absorption measurements. Furthermore, we show that the optical properties of the molds and their roughness can be tuned by choosing the polymers (including biopolymers) for printing pillars and tracks, thus bringing new possibilities for nanomolding of polymer surfaces for photonics, organic electronics and bioelectronics. PMID:26369185

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    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.

  15. A Conducting Polymer Film Stronger Than Aluminum

    NASA Astrophysics Data System (ADS)

    Shi, Gaoquan; Jin, Shi; Xue, Gi; Li, Cun

    1995-02-01

    Polythiophene (Pth) was electrochemically deposited onto stainless steel substrate from freshly distilled boron fluoride-ethyl ether containing 10 millimoles of thiophene per liter. The free-standing Pth film obtained at an applied potential of 1.3 volts (versus Ag/AgCl) had a conductivity of 48.7 siemens per centimeter. Its tensile strength (1200 to 1300 kilograms per square centimeter) was greater than that of aluminium (1000 to 1100 kilograms per square centimeter). This Pth film behaves like a metal sheet and can be easily cut into various structures with a knife or a pair of scissors.

  16. A soluble and fluorescent new type thienylpyrrole based conjugated polymer: optical, electrical and electrochemical properties.

    PubMed

    Soganci, Tugba; Soyleyici, Hakan Can; Ak, Metin

    2016-06-01

    Recently, increased attention has been focused on the synthesis of soluble and processable conducting polymers due to interest in their potential application. For this purpose a new type electroactive 2,5-di(2-thienyl)pyrrole derivative was synthesized and its novel solution-processable and fluorescent polymer, namely poly(N-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)-3,4,5-tris(dodecyloxy)benzamide) (P(TPDOB)), was electrochemically synthesized. Characterization of the monomer and the polymer was performed by (1)H-NMR, (13)C-NMR, cyclic voltammetry, and UV-vis and fluorescence spectroscopy. This soluble polymer has very well-defined and reversible redox processes in the acetonitrile-lithium perchlorate (ACN/LiClO4) couple. Moreover, P(TPDOB) shows multielectrochromic behavior: blue in the oxidized state, caesious in the intermediate state and greenish in the neutral state. Also the copolymer consists of EDOT and TPDOB was synthesized by cyclic voltammetry. A copolymer film has superior electrochromic and electrical properties when compared with a homopolymer. Furthermore, the fluorescence features of the monomer and the polymer were investigated. Although the monomer is a violet light emitter, its polymer is a yellow light emitter. Synthesis of this new type solution-processable and fluorescent conducting polymer is an alternative to the conventional synthesis of soluble conducting polymers which allows the direct application of the conductive polymer to any desired surface for potential technological applications. PMID:27171850

  17. 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. PMID:27326791

  18. 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.

  19. 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.

  20. Interactions H.I.F.U. / polymer films

    NASA Astrophysics Data System (ADS)

    Hallez, L.; Touyeras, F.; Hihn, J.-Y.; Bailly, Y.

    2010-01-01

    In order to obtain the modification of a defined volume of a polymer layer, preliminary tests of sonication (HIFU 0.75 and 3 MHz) were carried out to obtain an accurate characterization of the acoustic fields as well as convective flow velocities measured close to the surface by Particle Image Velocimetry and luminol mapping. Then, sonication of a delimited zone of an acrylic resin deposited upon a stainless steel thin substrate highlighted a strong dependence of the polymerization or reticulation degree, with different exposure times and different power thresholds for the same final modification. The point was to examine the ability of the thin polymer film to absorb ultrasonic energy or to act as a perfect reflector which induces asymmetric cavitation and therefore violent collapses to take place close to the surface. In the first case, the wave absorption by the film is converted into heat and then acts for the polymer alteration under the high convective flow velocities. For the highest acoustic intensities and for the hardest films, cavitation occurs and the produced microbubbles oscillated and grow close to the surface. Then, the shocks resulting of the bubble collapse eroded mechanically the film.

  1. 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.

  2. Droplet manipulation on a liquid crystal and polymer composite film

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Tsou, Yu-Shih; Chu, Ting-Yu; Chen, Jun-Lin

    2010-08-01

    A droplet manipulation on a switchable surface using a liquid crystal and polymer composite film (LCPCF) based on phase separation is developed recently. The wettability of LCPCF is electrically tunable because of the orientation of liquid crystal directors anchored among the polymer grains. A droplet on LCPCF can be manipulated owning to the wettability gradient induced by spatially orientation of LC directors. We discuss the droplet manipulation on LCPCF and demonstrate several applications of LCPCF, such as polarizer-free displays, and human semen sensing.

  3. 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.

  4. Phase Separation Dynamics of Polymer Blend Films Containing Polymer-Grafted Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chung, H.-J.; Ohno, K.

    2005-03-01

    Polymer blends containing nanoparticles (NP) are important in advanced technologies including opto-electronic and biosensor devices. Upon adding methyl-terminated silica NP's [22nm (NPA)] at dilute concentrations, PMMA:SAN (50:50) films (650nm) undergo early, intermediate and late stages of morphology development, similar to a PMMA:SAN film (Wang & Composto, JCP (2000)). NP's partition into the PMMA-rich phase, and slow down the kinetics of domain growth. This result is consistent with a coalescence model that predicts ξ˜ (1 / η)^1/3 t^1/3, where ξ and η are the correlation length and PMMA viscosity, respectively (Chung et al., EPL (2004)). Although the bulk η agrees with this model, a microscopic understanding of the phase separation mechanism requires knowledge of polymer-NP and NP-NP interactions. To address this issue, well-characterized silica NP's (15 nm) with densely grafted PMMA [Mw = 1.8K (NPB) and 21K (NPC)] are employed as non-interacting fillers in the PMMA-rich phase. The impact of PMMA-grafted NP on the phase separation dynamics in films, as well as the rheology of PMMA/NP composites, is investigated. Specifically, phase separation was slowest for NPB relative to films containing NPA and NPC. These studies show that wetting and domain coarsening in polymer blend films can be controlled by the judicial addition of surface modified NP.

  5. Excitation energy migration in uniaxially oriented polymer films: A comparison between strongly and weakly organized systems

    NASA Astrophysics Data System (ADS)

    Bojarski, P.; Synak, A.; Kułak, L.; Baszanowska, E.; Kubicki, A.; Grajek, H.; Szabelski, M.

    2006-04-01

    The mechanism of multistep excitation energy migration in uniaxially oriented polymer films is discussed for strongly and weakly orientating dyes in poly(vinyl alcohol) matrix. The comparison between both types of systems is based on concentration depolarization of fluorescence, Monte-Carlo simulations and linear dichroism data. It is found that the alignment of transition dipole moments of fluorophores in the ordered matrix relative to the direction of polymer stretching exhibits strong effect on the concentration depolarization of fluorescence. In ordered matrices of flavomononucleotide and rhodamine 6G concentration depolarization of fluorescence remains quite strong, whereas for linear carbocyanines it is very weak despite effective energy migration.

  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. Dewetting dynamics of stressed viscoelastic thin polymer films.

    PubMed

    Ziebert, Falko; Raphaël, Elie

    2009-03-01

    Ultrathin polymer films that are produced, e.g., by spin coating are believed to be stressed since polymers are "frozen in" into out-of-equilibrium configurations during this process. In the framework of a viscoelastic thin-film model, we study the effects of lateral residual stresses on the dewetting dynamics of the film. The temporal evolution of the height profiles and the velocity profiles inside the film as well as the dissipation mechanisms are investigated in detail. Both the shape of the profiles and the importance of frictional dissipation vs viscous dissipation inside the film are found to change in the course of dewetting. The interplay of the nonstationary profiles, the relaxing initial stress, and the changes in the dominance of the two dissipation mechanisms caused by nonlinear friction with the substrate is responsible for the rich behavior of the system. In particular, our analysis sheds a different light on the occurrence of the unexpected maximum in the rim width obtained recently in experiments on polystyrene-polydimethylsiloxane systems. PMID:19391952

  8. 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.

  9. Study of ordered macroporous polymer films by templating breath figures

    NASA Astrophysics Data System (ADS)

    Song, Lulu

    2005-11-01

    Macroporous films with highly ordered pore patterns have many potential applications. Some examples include microstructured electrode surfaces, photonic band gap materials and filters for cell sorting and bio-interfaces. In this dissertation we discuss a "moist-casting" method to prepare hexagonally-ordered macroporous films with pore sizes in the range of sub-micron to several microns, where condensed water droplets ("breath figures") work as templates. Compared with other templating methods, this one is fast and simple. Well-ordered porous films can be obtained in tens of seconds and the pore size can be easily tailored and dynamically controlled by adjusting the casting conditions. More importantly, there is no need to remove the templates; water droplets just evaporate when the casting processes are finished. This study was carried out with the intention of characterizing the structures, understanding film-formation processes and exploring special properties and possible applications. For the structural characterization, film morphology was studied in detail by normal optical microscopy and laser scanning confocal microscopy (LSCM). Several interesting features have been revealed. Meanwhile, the degree of the order of the porous structures were characterized both in real space via Voronoi diagram and bond-orientational correlation function, and in reciprocal space via Fraunhofer diffraction pattern. To further understand the mechanism, the evaporation of the polymer solutions during the film formation was studied by monitoring their mass over time. Besides, the evolution of breath figures formed on the evaporating polymer solutions was in-situ recorded via a high-speed camera coupled to an optical microscope. Combined with the information on the film structures obtained via LSCM, explanations for some detailed features have been attempted. Wetting property of these films was studied in some detail. The films exhibited "lotus effect", mimicking natural non

  10. Thin Films Formed from Conjugated Polymers with Ionic, Water-Soluble Backbones.

    PubMed

    Voortman, Thomas P; Chiechi, Ryan C

    2015-12-30

    This paper compares the morphologies of films of conjugated polymers in which the backbone (main chain) and pendant groups are varied between ionic/hydrophilic and aliphatic/hydrophobic. We observe that conjugated polymers in which the pendant groups and backbone are matched, either ionic-ionic or hydrophobic-hydrophobic, form smooth, structured, homogeneous films from water (ionic) or tetrahydrofuran (hydrophobic). Mismatched conjugated polymers, by contrast, form inhomogeneous films with rough topologies. The polymers with ionic backbone chains are conjugated polyions (conjugated polymers with closed-shell charges in the backbone), which are semiconducting materials with tunable bad-gaps, not unlike uncharged conjugated polymers. PMID:25723354

  11. 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.

  12. 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.

  13. Electrooptic Kerr effect of porphyrin H-aggregates in polymer films: Polymer specific spectral blue shift

    NASA Astrophysics Data System (ADS)

    Suzuki, Masaya; Nakata, Kazuaki; Kuroda, Reiko; Kobayashi, Takayoshi; Tokunaga, Eiji

    2016-05-01

    J- and H-aggregates of porphyrin molecules (TPPS4) in spin-coated polymer films have been studied by electroabsorption and circular dichroism (CD) spectroscopy. A spectral blue shift of the H-band due to the electrooptic Kerr effect was observed for the first time. This occurs only for a polyvinylpyrrolidone (PVP) film, with negligibly small spectral shift observed in polyvinyl alcohol (PVA), polyvinyl sulfate (PVS), and polyacrylic acid (PAA) films, in contrast to the red shift of the J-band which is commonly observed for any host polymers. Accordingly, the CD activity in both of J- and H-bands is more enhanced in PVP films than in PVA films. The mechanism of the blue and red shifts of the respective H- and J-bands is discussed by invoking a helical structure in micro-aggregates, which is compatible with the CD spectra, based on the molecular rearrangement model. It is proved that blue- and red-shifts occur evenly to cancel each other in the H-band if a simple helical structure is assumed, in good agreement with no spectral shifts in the H-band in PVA, PVS, and PAA films.

  14. 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).

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

    SciTech Connect

    Green, Peter F.

    2015-01-13

    Executive Summary 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. Accomplishments: We developed: (1) fundamental principles that enabled the creation of thin film PNCs possessing more complex morphologies of homopolymers and block copolymer micellar systems [1-6]; (2) a new

  16. Localized entrapment of green fluorescent protein within nanostructured polymer films

    NASA Astrophysics Data System (ADS)

    Ankner, John; Kozlovskaya, Veronika; O'Neill, Hugh; Zhang, Qiu; Kharlampieva, Eugenia

    2012-02-01

    Protein entrapment within ultrathin polymer films is of interest for applications in biosensing, drug delivery, and bioconversion, but controlling protein distribution within the films is difficult. We report on nanostructured protein/polyelectrolyte (PE) materials obtained through incorporation of green fluorescent protein (GFP) within poly(styrene sulfonate)/poly(allylamine hydrochloride) multilayer films assembled via the spin-assisted layer-by-layer method. By using deuterated GFP as a marker for neutron scattering contrast we have inferred the architecture of the films in both normal and lateral directions. We find that films assembled with a single GFP layer exhibit a strong localization of the GFP without intermixing into the PE matrix. The GFP volume fraction approaches the monolayer density of close-packed randomly oriented GFP molecules. However, intermixing of the GFP with the PE matrix occurs in multiple-GFP layer films. Our results yield new insight into the organization of immobilized proteins within polyelectrolyte matrices and open opportunities for fabrication of protein-containing films with well-organized structure and controllable function, a crucial requirement for advanced sensing applications.

  17. 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.

  18. 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.

  19. Photonic multilayer sensors from photo-crosslinkable polymer films

    NASA Astrophysics Data System (ADS)

    Chiappelli, Maria; Hayward, Ryan C.

    2012-02-01

    Photo-crosslinkable copolymers containing pendent benzophenone (BP) groups provide a convenient means to fabricate multilayer polymer films. We describe the preparation of alternating multilayers of photo-crosslinkable poly(N-isopropylacrylamide) (PNIPAM), a water-swellable, temperature sensitive polymer, and poly(para-methylstyrene) (PpMS), a non-swellable polymer, by sequential spin-coating and photo-crosslinking. This route provides well-defined layered structures with minimal interfacial broadening between layers and uniformity of thickness from layer to layer as determined by dynamic secondary ion mass spectrometry (d-SIMS). Appropriate choices of layer thicknesses yield 1-D photonic gel sensors. The reflectance peak is shifted through the visible spectrum upon swelling or de-swelling of the PNIPAM layers in water, providing an accessible means for colorimetric temperature sensing.

  20. 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.

  1. 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. PMID:20544886

  2. Recent Advances in the Improvement of Polymer Electret Films

    NASA Astrophysics Data System (ADS)

    Erhard, Dominik P.; Lovera, Deliani; von Salis-Soglio, Cosima; Giesa, Reiner; Altstädt, Volker; Schmidt, Hans-Werner

    Polymer electret materials are electrically charged dielectric polymers capable of quasi-permanently retaining their electric field. However, environmental influences such as temperature and humidity reduce their charge stability and restrict applications. Therefore it is of great importance to provide a broad pool of polymer electret materials and to enhance further the charge storage behavior. In this context we report on concepts, measures, and solutions to improve the electret performance of commodity and high performance thermoplastic polymers, which was carried out at the University of Bayreuth in recent years. It is demonstrated that the commodity polymer polypropylene can be manufactured into excellent electret films when certain trisamide additives are incorporated in very low concentrations. Polypropylene can be employed at temperatures up to its continuous service temperature of 70 ∘C. To achieve higher temperature windows we investigated the commodity blend system of poly(phenylene ether) (PPE) and polystyrene (PS). We demonstrate that especially PPE/PS blend films with a composition of 75/25 exhibit remarkably good charge storage retention during the isothermal surface decay (ITPD) tests at 120 ∘C. In addition, the commercially available high performance thermoplastic polyetherimide (PEI) resin containing special phosphorus(III) additives shows very good electret properties at elevated temperatures. These properties can be further enhanced by physical aging; resulting in a charge retention after 24 h at 120 ∘C as high as 95%. The same beneficial effect of physical aging can be used to advance PPE and PPE/PS blends. Polymer electret materials with such charge storage properties have the potential to be employed in microphones, sensor devices, and electret filters.

  3. 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.

  4. 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. PMID:27019963

  5. Graphene film formation on insulating substrates using polymer films as carbon source

    NASA Astrophysics Data System (ADS)

    Takami, T.; Seino, R.; Yamazaki, K.; Ogino, T.

    2014-03-01

    Graphene films were formed on sapphire surfaces using polymethylmethacrylate (PMMA) polymer films as a carbon source and characterized by Raman spectroscopy. For large-scale, uniform growth, a spin-on-glass (SOG)/Cu-catalyst/PMMA/sapphire layered structure was annealed in Ar-H2 flow at atmospheric pressure. We found that the SOG cover layer is effective to suppress evaporation and agglomeration of the Cu film. We also confirmed that morphology and quality of grown graphene films are dramatically improved by hydrogen etching of buried bulky carbon produced by the polymer pyrolysis at the Cu/sapphire interfaces. Quality of graphene films grown at the catalyst-layer/sapphire interface was compared with that on the catalyst surface using Ni/PMMA, PMMA/Ni and Ni/PMMA/Ni layered structures. Quality of graphene films grown at the Ni/sapphire interfaces was found to be lower than that on the Ni surfaces, suggesting that strain engineering at the buried Ni/graphene/sapphire interfaces and/or etching technique to remove the wastes of polymer pyrolysis should be improved.

  6. Characterization of polymer films retrieved from LDEF

    NASA Technical Reports Server (NTRS)

    Letton, Alan; Rock, Neil I.; Williams, Kevin D.; Strganac, Thomas W.; Farrow, Allan

    1992-01-01

    One of the trays aboard LDEF was an experiment having the objective of assessing the effects of long term exposure of candidate balloon films, tapes, and lines to the hostile environment of space. The fortuitous location of these materials on LDEF minimized direct impact by atomic oxygen thus providing an opportunity to study the effects of low earth orbit environments on polymeric materials without the worry of atomic oxygen abrasion. The resulting chemical, morphological, and thermomechanical changes for polyethylene specimens are reviewed. In addition, preliminary data for fluorinated ethylene/propylene copolymers used for thermal blankets is presented. Polyethylene is observed to crosslink and branch from exposure to atomic oxygen and/or ultraviolet with a decrease in crystallinity.

  7. Viscoelastic dewetting of a polymer film on a liquid substrate.

    PubMed

    Bodiguel, H; Fretigny, C

    2006-02-01

    The Dewetting of thin polymer films (60-300 nm) on a non-wettable liquid substrate has been studied in the vicinity of their glass transition temperature. In our experiment, we observe a global contraction of the film while its thickness remains uniform. We show that, in this case, the strain corresponds to simple extension, and we verify that it is linear with the stress applied by the surface tension. This allows direct measurement of the stress/strain response as a function of time, and thus permits the measurement of an effective compliance of the thin films. It is, however, difficult to obtain a complete viscoelastic characterization, as the short time response is highly dependant on the physical age of the sample. Experimental results underline the effects of residual stress and friction when dewetting is analyzed on rigid substrates. PMID:16491310

  8. Reduced Viscosity of Free Surface in Entangled Polymer Melt Films

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Li, C.; Endoh, M.; Koo, J.; Rafailovich, M.; Narayanan, S.; Lee, D.; Lurio, L.; Sinha, S.

    2010-03-01

    The dynamics of polymer chains near the surface of a melt and within thin films remains a subject of inquiry along with the nature of the glass transition in these systems. By embedding ``dilute'' gold nanoparticles in single polystyrene thin films as ``markers'', we could probe the local viscosity of the free surface at temperatures far above the glass transition temperature (Tg). The technique used was X-ray photon correlation spectroscopy with resonance-enhanced X-ray scattering. The results clearly showed the viscosity was about 30 % lower than the rest of the film. We found that this reduction is strongly associated with chain entanglements at the free surface rather than the reduction in Tg.

  9. Simple push coating of polymer thin-film transistors

    PubMed Central

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

    2012-01-01

    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. PMID:23132026

  10. 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.

  11. 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.

  12. Characterization of Local Mechanical Properties of Polymer Thin Films and Polymer Nanocomposites via AFM indentations

    NASA Astrophysics Data System (ADS)

    Cheng, Xu

    AFM indentation has become a tool with great potential in the characterization of nano-mechanical properties of materials. Thanks to the nanometer sized probes, AFM indentation is capable of capturing the changes of multiple properties within the range of tens of nanometers, such task would otherwise be difficult by using other experiment instruments. Despite the great potentials of AFM indentation, it operates based on a simple mechanism: driving the delicate AFM probe to indent the sample surface, and recording the force-displacement response. With limited information provided by AFM indentation, efforts are still required for any practice to successfully extract the desired nano-scale properties from specific materials. In this thesis, we focus on the mechanical properties of interphase between polymer and inorganic materials. It is known that in nanocomposites, a region of polymer exist around nanoparticles with altered molecular structures and improved properties, which is named as interphase polymer. The system with polymer thin films and inorganic material substrates is widely used to simulate the interphase effect in nanocomposites. In this thesis, we developed an efficient and reliable method to process film/substrate samples and characterize the changes of local mechanical properties inside the interphase region with ultra-high resolution AFM mechanical mapping technique. Applying this newly developed method, the interphase of several film/substrate pairs were examined and compared. The local mechanical properties on the other side of the polymer thin film, the free surface side, was also investigated using AFM indentation equipped with surface modified probes. In order to extract the full spectrum of local elastic modulus inside the surface region in the range of only tens of nanometers, the different contact mechanics models were studied and compared, and a Finite Element model was also established. Though the film/substrate system has been wide used as

  13. Application of Commercially Available Liquid Crystal Polymer Films for the Improvement of Color and Viewing Angle Performance of Twisted Nematic Devices

    NASA Astrophysics Data System (ADS)

    Tatiana A. Sergan,; Marina D. Lavrentovich,; Jack R. Kelly,; Tadayuki Kameyama,

    2010-06-01

    In our work we analyzed the optical performance of liquid crystal polymer films by Nippon Mitsubishi Oil and by Fuji Film. We applied the films for twisted nematic (TN) display compensation and found several non-traditional display configurations. One display configuration employs flipped Nippon Mitsubishi Oil films mounted on polarizers, the second one, a combination of both types of films on one TN side and two crossed uniaxial films on the other. The compensated devices demonstrate greatly improved optical characteristics that surpass all those previously known, utilize the commercially available films, and are experimentally verified.

  14. Evolution of non-equilibrium entanglement networks in spincast thin polymer films

    NASA Astrophysics Data System (ADS)

    Dalnoki-Veress, Kari; McGraw, Joshua; Fowler, Paul

    2012-02-01

    Measuring the rheology of non-equilibrium thin polymer films has received significant attention recently. Experiments are typically performed on thin polymer films that inherit their structure from spin coating. While the results of several rheological experiments paint a clear picture, details of molecular configurations in spincast polymer films are still unknown. Here we present the results of crazing measurements which demonstrate that the effective entanglement density of thin polymer films changes as a function of annealing toward a stable equilibrium value. The effective entanglement density plateaus with a time scale on the same order as the bulk reptation time.

  15. Laser-induced porous graphene films from commercial polymers

    PubMed Central

    Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

    2014-01-01

    Synthesis and patterning of carbon nanomaterials cost effectively is a challenge in electronic and energy storage devices. Here report a one-step, scalable approach for producing and patterning porous graphene films with 3-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF·cm−2 and power densities of ~9 mW·cm−2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices. PMID:25493446

  16. Reversible structuring of azobenzene polymer films by surface plasmons

    NASA Astrophysics Data System (ADS)

    Koenig, Tobias; Santer, Svetlana

    2010-03-01

    It should be possible to move adsorbed nano-objects with relative ease, in large number and simultaneously. The essential idea is not to put more effort in fighting against the prevailing surface forces but rather to utilize them - in clear contrast to current techniques of nano-manipulation with atomic force microscopy [Santer, Adv Mat 2006]. For this, the topography should be reversible switching between different states by changing the morphology at the scale of objects to be moved. In this work, we choose light for changing the polymer topography. Here we present azo thin films [Seki, Chem Soc Jpn 2007] with integrated optically active elements supposed to support and steer the response of polymer films to external illumination by acting as nano-scale antennas. During irradiation surface plasmon (SP) waves are generated on a metallic mask. The interaction of the SP waves with azo polymers results in printing of near field intensity distributions into topography with the pattern size below the diffraction limit. We found that the topography can be driven reversible by changing polarization or wavelength. We also examine how the structuring process depends on the size of the metallic patterns. The results are confirmed by FTDT simulations and compared with imprints of photolithographic mask.

  17. 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

  18. Laser-induced porous graphene films from commercial polymers.

    PubMed

    Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L G; Yacaman, Miguel Jose; Yakobson, Boris I; Tour, James M

    2014-01-01

    The cost effective synthesis and patterning of carbon nanomaterials is a challenge in electronic and energy storage devices. Here we report a one-step, scalable approach for producing and patterning porous graphene films with three-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp(3)-carbon atoms are photothermally converted to sp(2)-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF cm(-2) and power densities of ~9 mW cm(-2). Theoretical calculations partially suggest that enhanced capacitance may result from LIG's unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices. PMID:25493446

  19. Development of orodispersible polymer films with focus on the solid state characterization of crystalline loperamide.

    PubMed

    Woertz, Christina; Kleinebudde, Peter

    2015-08-01

    The formulation of active pharmaceutical ingredients (API) as orodispersible films is gaining interest among novel oral drug delivery systems due to their small size, enhanced flexibility and improved patient compliance. The aim of this work was the preparation and characterization of orodispersible films containing loperamide hydrochloride (LPH) as model drug. As loperamide hydrochloride is poorly soluble in water it was used in crystalline form with a loading of 2mg/6cm(2) film. Hydroxypropyl methylcellulose (HPMC) and different types of hydroxypropyl cellulose (HPC) in different concentrations were used as film forming polymers whereas arabic gum, xanthan gum and tragacanth served as thickening agents. Films were characterized with respect to the content uniformity, morphology, thermal behavior and crystallinity. Suspensions were investigated regarding their viscosity using a rotational rheometer and the crystal structure of the Active Pharmaceutical Ingredient (API) was analyzed using polarized light microscopy. The development of flexible, non-brittle and homogeneous films of LPH was feasible. Two polymorphic forms of LPH appeared in the film formulations dependent on the utilized polymer. While in presence of HPMC the original polymorphic form I remained stable in suspension and films, the polymorphic form II occurred in presence of HPC. Both polymorphic forms were prepared separately and a solid state characterization was performed. Polymorph I showed isometric crystals whereas polymorph II showed needle shaped crystals. Tragacanth was able to prevent the transformation to polymorph II, if it was dissolved first before HPC. When HPC was added first to the suspension, the conversion to form II occurred irreversibly also after further addition of tragacanth. PMID:25976316

  20. Piezoelectric characteristics of PZT thin films on polymer substrate

    NASA Astrophysics Data System (ADS)

    Kang, Min-Gyu; Do, Younh-Ho; Oh, Seung-Min; Rahayu, Rheza; Kim, Yiyein; Kang, Chong-Yun; Nahm, Sahn; Yoon, Seok-Jin

    2012-02-01

    The goal of piezoelectric energy harvesting is to improve the power efficiency of devices. One of the approaches for the improvement of power efficiency is to apply the large strain on the piezoelectric materials and then many scientists approached using thin films or nano-structured piezoelectric materials to obtain flexibility. However, the conventional thin film processes available for the fabrication of piezoelectric materials as PbZr0.52Ti0.48O3 (PZT) are not compatible with flexible electronics because they require high processing temperatures (>700^oC) to obtain piezoelectricity. Excimer laser annealing (ELA) is attractive heat process for the low-temperature crystallization, because of its material selectivity and short heating time. In this study, the amorphous PZT thin films were deposited on polymer substrate by rf-sputtering. To crystallize the amorphous films, the ELA was carried out with various conditions as function of the applied laser energy density, the number of pulse, and the repetition rate. To evaluate the piezoelectric characteristics, piezoelectric force microscopy (PFM) and electrometer are used. As a result, we obtained the crystallized PZT thin film on flexible substrate and obtained flexible piezoelectric energy harvester.

  1. Dynamics of polymer film formation during spin coating

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  2. Electrodeposited polymer encapsulated nickel sulphide thin films: frequency switching material

    NASA Astrophysics Data System (ADS)

    Jana, Sumanta; Mukherjee, Nillohit; Chakraborty, Biswajit; Mitra, Bibhas Chandra; Mondal, Anup

    2014-05-01

    Polyvinylpyrrolidone (PVP) encapsulated nickel sulfide (NiS) thin films have been synthesized electrochemically from aqueous solution of hydrated nickel chloride (NiCl2, 6H2O), thioacetamide (CH3C(S) NH2) (TAA) and polyvinylpyrrolidone (PVP). Surface modification of nickel sulfide (NiS) thin films was achieved by this polymer encapsulation. X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), field emission scanning electron microscopy (FESEM) and Energy dispersive X-radiation (EDAX) techniques were used for the characterization of thin films. Infrared spectroscopy (IR) confirmed the formation of polymer encapsulated semiconductor. Frequency switching generation study shows that the encapsulated material could be used as a frequency switching device that generates a frequency ∼ 50 Hz under 1 Sun illumination. Encapsulation with PVP causes surface modification that reduces the surface states and barrier height. As a result, the width of the depletion region decreases. So the number of electron-hole pairs increases. Consequently, the number of excitons and exciton related emission increases and this leads to reduction of recombination process and shows photo induced frequency switching phenomenon.

  3. Nanostructuring thin polymer films with optical near fields.

    PubMed

    Martín-Fabiani, Ignacio; Siegel, Jan; Riedel, Stephen; Boneberg, Johannes; Ezquerra, Tiberio A; Nogales, Aurora

    2013-11-13

    In the present work, we report on the application of optical near fields to nanostructuring of poly(trimethylene terephthalate) (PTT) thin films. By exposure to a single ultraviolet nanosecond laser pulse, the spatial intensity modulation of the near-field distribution created by a silica microsphere is imprinted into the films. Setting different angles of incidence of the laser, elliptical or circular periodic ring patterns can be produced with periods as small as half the laser wavelength used. These highly complex patterns show optical and topographical contrast and can be characterized by optical microscopy (OM) and atomic force microscopy (AFM). We demonstrate the key role of the laser wavelength and coherence length in achieving smooth, extended patterns in PTT by using excimer laser (193 nm) and Nd:YAG laser (266 nm) pulses. Reference experiments performed in Ge2Sb2Te5 (GST) demonstrate that nanopatterning in PTT is triggered by ablation as opposed to GST, in which nanopatterning originates from laser-induced phase change, accompanied by a small topographical contrast. The experiments presented in this work demonstrate the suitability of optical near fields for structuring polymer films, opening up new possibilities for nanopatterning and paving the way for potential applications where optical near fields and polymer nanostructures are involved. PMID:24127989

  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. Deformation in Thin Glassy Polymer Films from Surface towards Interior

    NASA Astrophysics Data System (ADS)

    Chowdhury, Mithun; de Silva, Johann P.; Cross, Graham L. W.

    Polymer thin glassy films occupy an important place in last two decades of condensed matter research, concerning its surprising surface mobility and spatially dependent structural relaxation. However, ranges of cleverly designed indirect measurements on confined polymer glassy films already probed its mechanical properties; it is still a challenging task to directly probe such small confined volume through conventional mechanical testing. We have designed confined layer compression testing with a precisely designed and aligned flat probe during nanoindentation, which was further accompanied with atomic force microscopy. Due to natural confinement from the surrounding material, we show that a state of `uniaxial strain' is created beneath the probe under small axial strains. By this methodology we are able to directly probe uniaxial flows under both anelastic and plastic conditions while doing controlled creep studies at different positions in the film starting from surface towards interior. Depending on the extent of deformation, we found ranges of effects, such as densification, anelastic yield, and plastic yield. Enhanced creep rate upon deformation supports the idea of `deformation induced mobility'. Work performed at Trinity College Dublin.

  6. Entanglement Density Changes in Free-Standing Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Stanzione, Joseph; Wool, Richard

    2013-03-01

    The entanglement molecular weight Me is obtained when a random walk chain crosses a plane three times to form a loop (R.P. Wool '83) such that for polymers with structure -CH2-CHX- where X is the side group, it is found that Me = 31 C∞ Mo/j, where C∞ is the characteristic ratio, Mo is the monomer mol weight and j =2 is the number of bonds per monomer. In thin films of thickness d < 2Rg, Me behaves as Me ~ d and this behavior is confirmed by computer simulation of random walks in thin films with reflecting boundary conditions. Thus, the entanglement density v ~ 1/Me increases as d decreases and rheological properties such as plateau modulus change as GNo ~ 1/d and plateau creep compliance Jo ~ d. The mechanical stiffening of thin films is in accord with recent experiments of McKenna et al (2012). The results are also in accord with the Packing model (Lin, Kavassil, Fetters 1983) where Me = 354 p3 in which p = Mo j/[C∞ bo2].The packing model is exactly derived from the Wool entanglement model for these polymers since C∞ = 1.36 [Mo/j]1/2. The empirical packing model with its excellent data correlation Me ~ p3 has been misinterpreted by many and such suggestions that v decreases due to nanoconfinement and GNo ~ d are incorrect.

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

    PubMed

    Yabu, Hiroshi; Hirai, Yuji; Shimomura, Masatsugu

    2006-11-01

    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. PMID:17073508

  8. 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.

  9. Reactions of atomic oxygen /O(3P)/ with polymer films

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.

    1992-01-01

    The reactions of polymer films with oxygen atoms are reviewed focusing on laboratory tests on polybutadienes with different amount of 1,4 or 1,2 double bonds and their polyalkenamer homologues, polyimide (Kapton), and a series of polyolefines with increasing fluorine content. It is found that etch rates increase with decrease in -CH=CH- unsaturation, starting with 1,4 -polybutadiene and reaching the maximum rate with polyethylene or ethylene-propylene rubber. IN polybutadienes with both 1,4 and 1,2 double bonds, the rate of O(3P)-induced etching is lower the higher the 1,2 content. The reactions are confined to the polymer surface.

  10. 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.

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

    PubMed Central

    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. PMID:26076355

  12. 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

  13. Photoluminescence quenching in films of conjugated polymers by electrochemical doping

    NASA Astrophysics Data System (ADS)

    van Reenen, S.; Vitorino, M. V.; Meskers, S. C. J.; Janssen, R. A. J.; Kemerink, M.

    2014-05-01

    An important loss mechanism in organic electroluminescent devices is exciton quenching by polarons. Gradual electrochemical doping of various conjugated polymer films enabled the determination of the doping density dependence of photoluminescence quenching. Electrochemical doping was achieved by contacting the film with a solid electrochemical gate and an injecting contact. A sharp reduction in photoluminescence was observed for doping densities between 1018 and 1019 cm-3. The doping density dependence is quantitatively modeled by exciton diffusion in a homogeneous density of polarons followed by either Förster resonance energy transfer or charge transfer. Both mechanisms need to be considered to describe polaron-induced exciton quenching. Thus, to reduce exciton-polaron quenching in organic optoelectronic devices, both mechanisms must be prevented by reducing the exciton diffusion, the spectral overlap, the doping density, or a combination thereof.

  14. 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

  15. Wrinkling, folding, and snapping instabilities in polymer films

    NASA Astrophysics Data System (ADS)

    Holmes, Douglas Peter

    This work focuses on understanding deformation mechanisms and responsiveness associated with the wrinkling, folding, and snapping of thin polymer films. We demonstrated the use of elastic instabilities in confined regimes, such as the crumpling and snapping of surface attached sheets. We gained fundatmental insight into a thin film's ability to localize strain. By taking advantage of geometric strain localization we were able to develop new strategies for responsive surfaces that will have a broad impact on adhesive, optical, and patterning applications. Using the rapid closure of the Venus flytrap's leaflets as dictated by the onset of a snap instability as motivation, we created surfaces with patterned structures to transition through a snap instability at a prescribed stress state. This mechanism causes surface topography to change over large lateral length scales and very short timescales. Changes in the stress state can be related to triggers such as chemical swelling, light-induced architecture transitions, mechanical pressure, or voltage. The primary advantages of the snap transition are that the magnitude of change, the rate of change, and the sensitivity to change can be dictated by a balance of materials properties and geometry. The patterned structures that exhibit these dynamics are elastomeric shells that geometrically localize strain and can snap between concave and convex curvatures. We have demonstrated the control of the microlens shell geometry and that the transition time follows scaling relationships presented for the Venus flytrap. Furthermore, the microlens arrays have been demonstrated as surfaces that can alter wettability. Using a similar novel processing technique, microarrays of freestanding elastomeric plates were placed in equibiaxial compression to fabricate crumpled morphologies with strain localized regions that are difficult to attain through traditional patterning techniques. The microstructures that form can be initially described

  16. π-Conjugated Microporous Polymer Films: Designed Synthesis, Conducting Properties, and Photoenergy Conversions

    PubMed Central

    Gu, Cheng; Huang, Ning; Chen, Youchun; Qin, Leiqiang; Xu, Hong; Zhang, Shitong; Li, Fenghong; Ma, Yuguang; Jiang, Donglin

    2015-01-01

    Conjugated microporous polymers are a unique class of polymers that combine extended π-conjugation with inherent porosity. However, these polymers are synthesized through solution-phase reactions to yield insoluble and unprocessable solids, which preclude not only the evaluation of their conducting properties but also the fabrication of thin films for device implementation. Here, we report a strategy for the synthesis of thin films of π-conjugated microporous polymers by designing thiophene-based electropolymerization at the solution–electrode interface. High-quality films are prepared on a large area of various electrodes, the film thickness is controllable, and the films are used for device fabrication. These films are outstanding hole conductors and, upon incorporation of fullerenes into the pores, function as highly efficient photoactive layers for energy conversions. Our film strategy may boost the applications in photocatalysis, energy storage, and optoelectronics. PMID:26418672

  17. 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.

  18. 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.

  19. Fabrication and mechanical characterization of semi-free-standing (conjugated) polymer thin films.

    PubMed

    Martín, Jaime; Muñoz, Miguel; Encinar, Mario; Calleja, Montserrat; Martín-González, Marisol

    2014-05-13

    Polymers undergo severe low-dimensionality effects when they are confined to ultrathin films since most of the structural and dynamical processes involving polymer molecules are correlated to length scales of the order of nanometers. However, the real influence of the size limitation over such processes is often hard to identify as it is masked by interfacial effects. We present the fabrication of a new type of nanostructure consisting of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) thin film that is held up exclusively over tips of poly(ether-ether-ketone) (PEEK) nanopillars. The fabrication method exploits the nonwetting behavior of PCDTBT onto an ordered PEEK nanopillar array when the mobility of the PCDTBT molecules is enhanced by a solvent annealing process. We use this new configuration to characterize the mechanical behavior of free-standing thin film regions, thus in the absence of underlaying substrate, by means of an atomic force microscope (AFM) setup. First, we study how the finite thickness and/or the presence of the underlying substrate influences the mechanical modulus of the material in the linear elastic regime. Moreover, we analyze deep indentations up to the rupture of the thin film, which allow for the measurement of important mechanical features of the nanoconfined polymer, such as its yield strain, the rupture strain, the bending rigidity, etc., which are impossible to investigate in thin films deposited on substrates. PMID:24111564

  20. 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. PMID:25127447

  1. Effect of crystalline microstructure on the photophysical performance of polymer/perylene composite films

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Xu, You-Long; Yi, Wen-Hui; Zhou, Feng; Wang, Xiao-Gong; Katsumi, Yoshino

    2003-04-01

    To obtain high carrier mobility, better charge injection capability and high photovoltaic device conversion efficiency, a powerful strategy is to improve the morphology of the polymer/dye composite films. Conjugated conducting polymer (CP) thin films doped with perylene derivative (PV) of various concentrations were prepared by spin-casting method and their morphology and photovoltaic characteristics were examined. The change in morphology and molecular reorientation occurring in CP-PV composite films upon annealing at different temperatures was investigated using scanning electron microscopy, x-ray diffraction, Fourier transform infrared and UV-vis absorption. By changing the annealing temperature, PV microcrystallines of 8-10µm in size lying parallel to the substrate surface can be obtained. Annealing effect improved the photovoltaic performance of ITO/CP-PV/Al Schottky-type solar cells, which can be attributed to the formation of an electron conducting PV crystal network. Preliminary studies indicate that the morphological structure in CP-PV composite films has an important influence to their photovoltaic properties.

  2. 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.

  3. 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

  4. Thin polymer films of block copolymers and blend/nanoparticle composites

    NASA Astrophysics Data System (ADS)

    Kalloudis, Michail

    In this thesis, atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical microscopy techniques were used to investigate systematically the self-assembled nanostructure behaviour of two different types of spin-cast polymer thin films: poly(isoprene-b-ethylene oxide), PI-b-PEO diblock copolymers and [poly(9,9-dioctylfluorene-co-benzothiadiazole)]:poly[9,9- dioctyfluorene-co-N-(4-butylphenyl)-diphenylamine], F8BT:TFB conjugated polymer blends. In the particular case of the polymer blend thin films, the morphology of their composites with cadmium selenide (CdSe) quantum dot (QD) nanoparticles was also investigated. For the diblock copolymer thin films, the behaviour of the nanostructures formed and the wetting behaviour on mica, varying the volume fraction of the PEO block (fPEO) and the average film thickness was explored. For the polymer blend films, the effect of the F8BT/TFB blend ratio (per weight), spin-coating parameters and solution concentration on the phase-separated nanodomains was investigated. The influence of the quantum dots on the phase separation when these were embedded in the F8BT:TFB thin films was also examined. It was found that in the case of PI-b-PEO copolymer thin films, robust nanostructures, which remained unchanged after heating/annealing and/or ageing, were obtained immediately after spin coating on hydrophilic mica substrates from aqueous solutions. The competition and coupling of the PEO crystallisation and the phase separation between the PEO and PI blocks determined the ultimate morphology of the thin films. Due to the great biocompatible properties of the PEO block (protein resistance), robust PEO-based nanostructures find important applications in the development of micro/nano patterns for biological and biomedical applications. It was also found that sub-micrometre length-scale phase-separated domains were formed in F8BT:TFB spin cast thin films. The nanophase-separated domains of F8BT-rich and TFB-rich areas

  5. 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

  6. 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.

  7. An electrochromic film device to teach polymer electrochemical physics

    NASA Astrophysics Data System (ADS)

    Huang, Mei-Rong; Tao, Tao; Li, Xin-Gui; Gong, Qian-Cheng

    2007-09-01

    We discuss the background associated with an electrochromic device that can reversibly change its color and optical density at a specific potential. We discuss the underlying science needed to make a new polyaniline (PAN)/polyvinyl alcohol(PVA) electrochromic composite film on an indium-tin oxide (ITO) conducting glass by electropolymerization and describe a reversible redox transition of the PAN. The experiment gives students an opportunity to fabricate an electrochromic device containing PAN, one of the most important conducting polymers. The experimental conditions are flexible so that each group of students can construct their own electrochromic device with particular behavior. Two techniques for polymerizing the PAN and three methods of demonstrating the electrochromism are given, depending on the available apparatus. A sophisticated three-electrode potentiostat or a crude apparatus containing a battery, wire, a variable resistor, and a voltage meter is used to synthesize the PAN deposit. The electrochromic property is repetitively observed by reversibly changing the applied potentials on the device. A potentiostatic apparatus, a single flashlight battery, or a flashlight battery accompanied by a variable resistor allows students to observe multicolor electrochromism. The experiments significantly enhance students' understanding of polymer chemicophysics principles and their appreciation of novel variable colorful films. The experiments are safe and easy to perform, provided that appropriate precautions are taken.

  8. Irradiation resistant Carbon nanotube/polymer nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Najafi, Ebrahim; Shin, Kwanwoo; Kim, Jae-Yong

    2004-03-01

    Degradation of Poly (methyl methacrylate)-multi-walled carbon nanotube (MWNT) nanocomposite thin films, using a UV-ozone and an e-beam radiation as a function of MWNT concentration was studied. We have shown that the addition of MWNT fillers can have a dramatic reinforcement effect on the nature of degradation by both high-energy radiations, where polymer free radicals are mainly responsible for the proliferation of degradation. In addition, MWNT networks can effectively disperse the radiation. The saturation in the reinforcement effect was observed when a concentration of MWNT was approximately 0.5 wt interpreted in terms of a critical concentration for percolation of the MWNT network, and the result was consistent with the sheet resistivity measurement for which physical contact between MWNT fibers was evident. Thermal stability of these films was also studied and higher activation energies for thermal degradation of the polymer matrix were observed as a function of MWNT concentration. Part of this work was supported by the Ministry of Science and Technology of Korea through Proton Accelerator User Program (No. M102KS010001-02K1901-01810).

  9. Slippage and nanorheology of thin liquid polymer films.

    PubMed

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

    2012-08-15

    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. PMID:22647885

  10. 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.

  11. Dynamic hairspray analysis. II. Effect of polymer, hair type, and solvent composition.

    PubMed

    Jachowicz, J; Yao, K

    2001-01-01

    A texture analyzer was employed to study the properties of hairspray resins by measuring a number of mechanical parameters of hair modified by them. Hairset stiffness, stiffness retention at high humidity, and duration and magnitude of polymer film tackiness during drying were the properties employed to characterize fixative-treated hair. They were investigated for formulations containing ethyl ester of PVM/MA copolymer, butyl ester of PVM/MA copolymer, vinyl caprolactam/PVP/dimethylaminoethyl methacrylate copolymer, VA/butyl maleate/isobornyl acrylate copolymer, and polymer blends such as poly(methylvinylether) (PMVE) - ethyl ester of PVM/MA copolymer. It was demonstrated that the properties of hair treated with a fixative are affected by the concentration and molecular weight of a polymer, low-molecularweight additives that can modify the mechanical, surface, or interfacial properties of a polymer film, and the presence of water in the formulation. It was also shown, that the type of hair employed, such as virgin, untreated hair or hair damaged by bleaching, can also have an effect on the performance of a given hairspray formulation. For compositions based on blends of PMVE and ethyl ester of PVM/MA copolymer, the employed method demonstrated the sensitivity of the properties of polymer blends to the presence of a hydrophilic component such as PMVE. PMID:11567208

  12. 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.

  13. 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. PMID:25430142

  14. 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. PMID:22619031

  15. Polymer film deposition on agar using a dielectric barrier discharge jet and its bacterial growth inhibition

    NASA Astrophysics Data System (ADS)

    Tsai, T.-C.; Cho, J.; Mcintyre, K.; Jo, Y.-K.; Staack, D.

    2012-08-01

    Polymer film deposition on agar in ambient air was achieved using the helium dielectric barrier discharge jet (DBD jet) fed with polymer precursors, and the bacterial growth inhibition due to the deposited film was observed. The DBD jet with precursor addition was more efficient at sterilization than a helium-only DBD jet. On the areas where polymer films cover the agar the bacterial growth was significantly inhibited. The inhibition efficacy showed dependence on the film thickness. The DBD jet without precursor also created a modified agar layer, which may slow the growth of some bacterial strains.

  16. Polarization and piezoelectricity in polymer films with artificial void structure

    NASA Astrophysics Data System (ADS)

    Sun, Zhuanlan; Zhang, Xiaoqing; Xia, Zhongfu; Qiu, Xunlin; Wirges, Werner; Gerhard, Reimund; Zeng, Changchun; Zhang, Chuck; Wang, Ben

    2011-10-01

    Laminated polymer-film systems with well-defined void structures were prepared from fluoroethylenepropylene (FEP) and polytetrafluoroethylene (PTFE) layers. First the PTFE films were patterned and then fusion-bonded with the FEP films. The laminates were subjected to either corona or contact charging in order to obtain the desired piezoelectricity. The build-up of the "macro-dipoles" in the laminated films was studied by recording the electric hysteresis loops. The resulting electro-mechanical properties were investigated by means of dielectric resonance spectroscopy (DRS) and direct measurements of the stress-strain relationship. Moreover, the thermal stability of the piezoelectric d 33 coefficient was investigated at elevated temperatures and via thermally stimulated discharge (TSD) current measurements in short circuit. For 150 μm thick laminated films, consisting of one 25 μm thick PTFE layer, two 12.5 μm thick FEP layers, and a void of 100 μm height, the critical voltage necessary for the build-up of the "macro-dipoles" in the inner voids was approximately 1400 V, which agrees with the value calculated from the Paschen Law. A quasi-static piezoelectric d 33 coefficient up to 300 pC/N was observed after corona charging. The mechanical properties of the film systems are highly anisotropic. At room temperature, the Young's moduli of the laminated film system are around 0.37 MPa in the thickness direction and 274 MPa in the lateral direction, respectively. Using these values, the theoretical shape anisotropy ratio of the void was calculated, which agrees well with experimental observation. Compared with films that do not exhibit structural regularity, the laminates showed improved thermal stability of the d 33 coefficients. The thermal stability of d 33 can be further improved by pre-aging. E.g., the reduction of the d 33 value in the sample pre-aged at 150°C for 5 h was less than 5% after annealing for 30 h at a temperature of 90°C.

  17. 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

  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. p-Type polymer-hybridized high-performance piezoelectric nanogenerators.

    PubMed

    Lee, Keun Young; Kumar, Brijesh; Seo, Ju-Seok; Kim, Kwon-Ho; Sohn, Jung Inn; Cha, Seung Nam; Choi, Dukhyun; Wang, Zhong Lin; Kim, Sang-Woo

    2012-04-11

    Enhancing the output power of a nanogenerator is essential in applications as a sustainable power source for wireless sensors and microelectronics. We report here a novel approach that greatly enhances piezoelectric power generation by introducing a p-type polymer layer on a piezoelectric semiconducting thin film. Holes at the film surface greatly reduce the piezoelectric potential screening effect caused by free electrons in a piezoelectric semiconducting material. Furthermore, additional carriers from a conducting polymer and a shift in the Fermi level help in increasing the power output. Poly(3-hexylthiophene) (P3HT) was used as a p-type polymer on piezoelectric semiconducting zinc oxide (ZnO) thin film, and phenyl-C(61)-butyric acid methyl ester (PCBM) was added to P3HT to improve carrier transport. The ZnO/P3HT:PCBM-assembled piezoelectric power generator demonstrated 18-fold enhancement in the output voltage and tripled the current, relative to a power generator with ZnO only at a strain of 0.068%. The overall output power density exceeded 0.88 W/cm(3), and the average power conversion efficiency was up to 18%. This high power generation enabled red, green, and blue light-emitting diodes to turn on after only tens of times bending the generator. This approach offers a breakthrough in realizing a high-performance flexible piezoelectric energy harvester for self-powered electronics. PMID:22409420

  20. Polymer films as planarization and sacrificial layers for uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Liu, Weiguo; Cai, Changlong; Zhou, Shun

    2010-10-01

    This paper presents a planarization procedure using polymer films to achieve a flat CMOS surface of Readout Integrated Circuit (ROIC) for the integration between uncooled infrared focal plane arrays and ROIC. At the same time, the polymer film is also used as the sacrificial layers. After amorphous Silicon (a-Si) film was deposited using plasma enhanced chemical vapor deposition (PECVD), and patterned using inductively coupled plasma (ICP), the polymer sacrificial layer should be removed to form a-Si self-supporting micro-bridge structure. So the thickness of polymer film determine the height of the micro-bridge; the soft curing temperature determines if the contact hole can be etched by developer during the first photolithography; and the rate of dry etching determines whether the sacrificial layers of the structure can be released successfully. In this paper, the curing temperature, surface roughness, etching process of polymer films are systematically researched. On this basis, polymer film as planarization successfully reduces the 2μm height of the bumps on ROIC to less than 83 nm, over the planarized polymer mesas, bolometer arrays are fabricated. Then the polymer film as sacrificial are removed by ICP and 160x120 self-supporting micro-bridge structure arrays are successfully fabricated.

  1. Polymer films as planarization and sacrificial layers for uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Liu, Weiguo; Cai, Changlong; Zhou, Shun

    2011-02-01

    This paper presents a planarization procedure using polymer films to achieve a flat CMOS surface of Readout Integrated Circuit (ROIC) for the integration between uncooled infrared focal plane arrays and ROIC. At the same time, the polymer film is also used as the sacrificial layers. After amorphous Silicon (a-Si) film was deposited using plasma enhanced chemical vapor deposition (PECVD), and patterned using inductively coupled plasma (ICP), the polymer sacrificial layer should be removed to form a-Si self-supporting micro-bridge structure. So the thickness of polymer film determine the height of the micro-bridge; the soft curing temperature determines if the contact hole can be etched by developer during the first photolithography; and the rate of dry etching determines whether the sacrificial layers of the structure can be released successfully. In this paper, the curing temperature, surface roughness, etching process of polymer films are systematically researched. On this basis, polymer film as planarization successfully reduces the 2μm height of the bumps on ROIC to less than 83 nm, over the planarized polymer mesas, bolometer arrays are fabricated. Then the polymer film as sacrificial are removed by ICP and 160x120 self-supporting micro-bridge structure arrays are successfully fabricated.

  2. 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.

  3. Controlling the adhesion of conducting polymer films with patterned self-assembled monolayers

    SciTech Connect

    Rozsnyai, L.F.; Wrighton, M.S.

    1996-02-01

    A photosensitive self-assembled monolayer (SAM) is selectively irradiated to fabricate a pattern on an Au electrode, and a thin film of aniline or 3-methylthiophene is deposited on it by electopolymerization. Adhesion of the polymer films can be controlled by the monolayer terminal group. Applying tape to the sample and peeling it away selectively removes the conducting polymer film to the tape in a near-micron resolution pattern. 14 refs., 1 fig.

  4. Buckling instabilities of nanoscale polymer films and colloidal particle layers

    NASA Astrophysics Data System (ADS)

    Gurmessa, Bekele Jemama

    Nanoscale polymer films have numerous potential applications such as protective coatings, flexible electronics, energy harvesting devices, and drug delivery systems. For realization of these potential applications, the mechanical properties of these materials and the underlying physics need to be understood. This dissertation focuses on understanding the responses of nanoscale films to mechanical deformations. In this regard, an elastic instability was exploited to locally bend and impart a local tensile stress in a nanoscale polystyrene film, and directly measure the resulting residual stress caused by the bending. Our results indicate that the onset of permanent deformation for thin polystyrene films is an order of magnitude smaller than what has been reported for the bulk value. In addition, not only is the onset of failure strain found to be small but also it increases with increased confinement. Using similar processing techniques, the yield strain of a more complex material---poly(styrene-b-divinylpyridine)---was studied. Similar to the polystyrene films, failure in polystyrene-b-poly(2-vinylpyridine) is also initiated at extremely low strain and is influenced by thin film confinement effects. In addition, we have demonstrated that internal nanostructure of self-assembled polystyrene-b-poly(2-vinylpyridine) affects the onset of failure strain. Having introduced an idealized heterogeneity to a sample through ultraviolet/ozone treatment, we have created samples ranging from continuous thin films to sets of isolated plates. We demonstrated that, when subjected to mechanical deformation, the unbounded plates form isotropic undulations that persist even beyond high strain. In contrast, isolated plates undergo non-isotropic undulations in the range of high strains. The non-isotropic undulation shape has been described through a simple numerical modeling subjected to controlled boundary conditions. The agreement between experiment and numerical modeling is

  5. 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

  6. Processing of functional polymers and organic thin films by the matrix-assisted pulsed laser evaporation (MAPLE) technique

    NASA Astrophysics Data System (ADS)

    Piqué, A.; Wu, P.; Ringeisen, B. R.; Bubb, D. M.; Melinger, J. S.; McGill, R. A.; Chrisey, D. B.

    2002-01-01

    The matrix-assisted pulsed laser evaporation (MAPLE) technique has been successfully used to deposit highly uniform thin films of various functional materials such as non-linear optical (NLO) organic materials, conductive polymers, luminescent organic molecules and several types of proteinaceous compounds. MAPLE is a laser evaporation technique for growing thin films of organic and polymeric materials which involves directing a pulsed laser beam (λ=193 nm; fluence=0.01-0.5 J cm -2) onto a frozen target (-40 to -160 °C) consisting of a solute polymeric or organic compound dissolved in a solvent matrix. Using MAPLE, thin films of N-(4-nitrophenyl)-( L)-prolinol or NPP, an NLO material; polypyrrole, a conductive polymer; and tris-(8-hydroxyquinoline) aluminum or Alq3, a luminescent organic compound, have been separately deposited with minor (in the case of Alq3) or no degradation (for the NPP and polypyrrole) to their optical and electrical properties. The MAPLE process has also been used to deposit discrete thin film micro-arrays of biotinylated bovine serum albumin (BSA). The deposited BSA films, after washing with a blocking protein and fluorescently tagged streptavidin, fluoresce when exposed to UV. This fluorescence indicates that the biochemical specificity of the transferred biotinylated protein is unaffected by the MAPLE process. These results demonstrate that the MAPLE technique can be used for growing thin films of functional polymer and active biomaterials.

  7. 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.

  8. Effect of Polymer Deposition Method on Thermoresponsive Polymer Films and Resulting Cellular Behavior

    PubMed Central

    Reed, JA; Love, SA; Lucero, AE; Haynes, CL; Canavan, HE

    2013-01-01

    Poly(N-isopropyl acrylamide) or pNIPAM is a thermoresponsive polymer that is widely studied for use in bioengineering applications. The interest in this polymer lies in the polymer’s unique capability to undergo a sharp property change near physiological temperatures, which aids in the spontaneous release of biological cells from substrates. Currently, there are many methods to deposit pNIPAM onto substrates, including atom transfer radical polymerization (ATRP) and electron beam ionization. Each method yields pNIPAM coated substrates with different surface characteristics which can influence cell behavior. In this work, we compare two methods of pNIPAM deposition: plasma deposition and co-deposition with a sol gel. The resulting pNIPAM films were analyzed for use as substrates for mammalian cell culture based on surface characterization (XPS, ToF-SIMS, AFM, contact angles), cell attachment/detachment studies, and an analysis of exocytosis function using carbon-fiber microelectrode amperometry (CFMA). We find that, although both methods are useful for the deposition of functional pNIPAM films, plasma deposition is much preferred for cell-sheet engineering applications due to the films’ thermoresponse, minimal change in cell density, and maintenance of supported cell exocytosis function. PMID:21506526

  9. Fluorescent cross-linked supramolecular polymers constructed from a novel self-complementary AABB-type heteromultitopic monomer.

    PubMed

    Fang, Le; Hu, Yuanli; Li, Qiang; Xu, Shutao; Dhinakarank, Manivannan Kalavathi; Gong, Weitao; Ning, Guiling

    2016-04-26

    A novel AABB-type heteromultitopic monomer (), having a self-complementary perpendicular structure, could solely self-assemble to fluorescent cross-linked supramolecular polymers. Interestingly, the supramolecular gel film shows a sensitive fluorescence change on exposure to acid and base vapor, endowing this system with a potential application in gas detection. PMID:27005489

  10. The Impact of Polymer Dynamics on Photoinduced Carrier Formation in Films of Semiconducting Polymers.

    PubMed

    Ogata, Yudai; Kawaguchi, Daisuke; Tanaka, Keiji

    2015-12-01

    A better understanding of the carrier formation process in photosemiconducting polymers is crucial to design and construct highly functionalized thin film organic photodevices. Almost all studies published focus on the effect of structure on the photoinduced carrier formation process. Here, we study the dynamics of polymer chain impacts on the carrier formation process for a series of poly(3-alkylthiophene)s (P3ATs) with different alkyl side-chain lengths. The formation of polarons (P) from polaron pairs (PP) was accelerated at a temperature at which the twisting motion of thiophene rings occurs. Among all P3ATs employed, in P3AT with hexyl groups, or poly(3-hexylthiophene) (P3HT), it was easiest to twist the thiophene rings and generate P from PP. The activation energy for P formation was proportional to that of thiophene ring motion. This makes it clear that chain dynamics, in addition to the crystalline structure, is a controlling factor for the carrier formation process in photosemiconducting polymers. PMID:26574654

  11. Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

    SciTech Connect

    Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A.; Orler, E. Bruce; Kortright, Jeffrey B

    2008-04-04

    We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends on both the real and imaginary parts of the atomic scattering factors. Using a model polymer film of poly(styrene-b-methyl methacrylate), we show that the soft x-ray reflectivity data is much more sensitive to these atomic scattering factors than the soft x-ray scattering data. Nevertheless, fits to both types of data yield useful morphological details on the polymer?slamellar structure that are consistent with each other and with literature values.

  12. The viscoelastic properties of ultrathin polymer films as measured with a novel nanobubble inflation technique.

    NASA Astrophysics Data System (ADS)

    Oconnell, Paul; McKenna, Gregory

    2008-03-01

    Using a nano-bubble inflation technique developed within our laboratory, we have measured the absolute biaxial compliance of polymer films as thin as 11.3 nm. Previous results have shown that the degree of reduction in Tg with film thickness is not universal viz., PVAc shows no reduction even for the thinnest films while the PS shows a significant reduction at a thickness below approximately 80nm. In addition the rubbery plateau region for both materials shows dramatic stiffening as the thickness is reduced (>300 times) and scales as approximately the square of film thickness. We have extended the analysis of the data to directly determine the creep compliance function from the measured data rather than the minimization routine used previously. Creep compliance master curves constructed from data at varying thicknesses show that time-temperature superposition is valid even at the thinnest film thickness. The time-temperature shift factors are consistent with a WLF-type dependence and indicate a reduction in Tg for PS at 11.3nm of 53K while no significant reduction (< 3K) is seen for PVAc.

  13. Formation of polymer thin films and interface control by physical vapor deposition

    NASA Astrophysics Data System (ADS)

    Usui, Hiroaki

    2009-08-01

    Some strategies of physical vapor deposition (PVD) of polymer thin films have been proposed. Direct vapor deposition can be applied for simple polymers like polyethylene and Teflon. Coevaporation of bifunctional monomers can be achieved to deposit polyimide, polyurea etc., while chain polymerization assisted by ultraviolet or electron irradiation can be used to form vinyl or acryl polymers from single evaporation source. Surface-initiated deposition polymerization, which combines the self-assembled monolayer and vapor deposition, is another unique method to grow polymer thin films that are chemically bound to the substrate surface. The last method is also effective in controlling the interface between polymer films and inorganic substrates. The solvent-free nature of PVD is convenient for the formation of nanometer-thick films and especially multilayers that are required for device fabrication. Application of vapor deposition polymerization for fabrication of organic light-emitting diode is also described.

  14. 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.

  15. 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. PMID:26953514

  16. Microcontact printing for patterning carbon nanotube/polymer composite films with electrical conductivity.

    PubMed

    Ogihara, Hitoshi; Kibayashi, Hiro; Saji, Tetsuo

    2012-09-26

    Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (μCP). To prepare ink for μCP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during μCP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites. PMID:22900673

  17. 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.

  18. Electronic durability of flexible transparent films from type-specific single-wall carbon nanotubes.

    PubMed

    Harris, John M; Iyer, Ganjigunte R Swathi; Bernhardt, Anna K; Huh, Ji Yeon; Hudson, Steven D; Fagan, Jeffrey A; Hobbie, Erik K

    2012-01-24

    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. PMID:22148890

  19. Pushing the boundaries of spatial resolution in dosimetry using polymer gels and radiochromic films

    NASA Astrophysics Data System (ADS)

    Heilemann, G.; Georg, D.; Berg, A.

    2015-01-01

    Advanced radiotherapy and brachytherapy techniques are raising the bar for detectors with respect to high spatial resolution. Dosimetry based on most point-like dosimeters, e.g. diamond detectors or small volume ionization chambers cannot be used efficiently and accurately for detecting 2 or 3D-dose variations at millimeter scale. Hence radiochromic films and polymer gels with high two/three-dimensional resolution provide a good verification tool for measuring dose distributions of very small collimated beams. In this study the performance of film and gel detectors in detecting the very fine dose distributions generated from collimation holes of four different sizes is investigated. Pencil beams with diameters down to 0.455 mm could be resolved by both detector types comparably.

  20. 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.

  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. Nanometer voids prevent crack growth in polymer thin films

    NASA Astrophysics Data System (ADS)

    Yokoyama, Hideaki; Dutriez, Cedric; Satoh, Kotaro; Kamigaito, Masami

    2007-03-01

    Macroscopic voids initiate cracks and cause catastrophic failure in brittle materials. The effect of micrometer voids in the mechanical properties of polymeric materials was studied in 1980's and 90's with the expectation that such small voids may initiate crazing, the toughening mechanism in polymer solids, similar to dispersed rubber particles widely used in industry. However, the micrometer voids showed only limited resistance against crack growth, and it was concluded that much smaller voids are necessary for the drastic change in mechanical properties. We have recently succeeded the nondestructive introduction of nanometer voids (30--70 nm) in polymeric materials using block copolymer template and carbon dioxide (CO2) by partitioning CO2 in CO2-philic nanodomains of block copolymers. The reduction of Young's modulus with such nanometer voids was minimal (2 to 1 GPa) due to the (short-range) ordered spherical voids. While the unprocessed copolymer films failed in brittle manner at around 2 % of tensile strain, the processed copolymer films with nanometer voids did not break up to at least 60 %. A microscopic observation under strain of the crack tip revealed that the nanometer voids were deformed under strain and directly converted into the networked fibrils near the crack tip similar to crazing and thus prevented the crack growth.

  3. Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.

    PubMed

    Wang, Junjie; Wang, Meng; Xu, Jian; Peng, Li; Yang, Minghong; Xia, Minghe; Jiang, Desheng

    2014-10-01

    This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55 MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767 μs. Finally, three aspects that need further study for practical use are pointed out. PMID:25322237

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    N,N'-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN2 film is much lower than the value of PDIF-CN2 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-CN2 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-CN2 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 cm2/V s has been achieved from OTFTs based on the PDIF-CN2 film with the pre-deposition of PαMS polymer.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Schmitt, T.; Guttmann, P.; Schmidt, O.; Müller-Buschbaum, P.; Stamm, M.; Schönhense, G.; Schmahl, G.

    2000-05-01

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

  7. Fabry Perot polymer film fibre-optic hydrophones and arrays for ultrasound field characterisation

    NASA Astrophysics Data System (ADS)

    Cox, B. T.; Zhang, E. Z.; Laufer, J. G.; Beard, P. C.

    2004-01-01

    An optical ultrasound sensing method based upon the detection of acoustically-induced changes in the optical thickness of a Fabry Perot (FP) polymer film sensing interferometer has been developed as an alternative to piezoelectric based detection methods for ultrasound measurement applications. The technique provides an inherently broadband (~30 MHz) response and excellent detection sensitivities (<10 kPa), comparable to those of piezoelectric PVDF transducers. An important distinguishing feature however is that the sensing geometry is defined by the area of the polymer sensing film that is optically addressed. As a result, very small element sizes can be obtained to provide low directional sensitivity without compromising detection sensitivity—a key advantage over piezoelectric transducers. It also means that, by spatially sampling over a relatively large aperture, a high density ultrasound array can readily be configured. Other advantages are that, the sensing element can be inexpensively batch fabricated using polymer film deposition techniques, has the ability to self-calibrate, is electrically passive and immune to EMI. A range of measurement devices using this type of sensor have now been developed. These include a miniature (0.25 mm o.d.) optical fibre hydrophone for in situ measurements of diagnostic and therapeutic medical ultrasound exposure. By rapidly scanning a focused laser beam over a planar FP sensor, a notional array of 3 cm aperture, 50 µm element size and 200 µm interelement spacing has also been demonstrated for rapid transducer field mapping applications. It is considered that this ability to fabricate acoustically small, highly sensitive receivers in a variety of configurations offers the prospect of developing a valuable new set of ultrasound measurement tools.

  8. Rewritable Optical Storage with a Spiropyran Doped Liquid Crystal Polymer Film.

    PubMed

    Petriashvili, Gia; De Santo, Maria Penelope; Devadze, Lali; Zurabishvili, Tsisana; Sepashvili, Nino; Gary, Ramla; Barberi, Riccardo

    2016-03-01

    Rewritable optical storage has been obtained in a spiropyran doped liquid crystal polymer films. Pictures can be recorded on films upon irradiation with UV light passing through a grayscale mask and they can be rapidly erased using visible light. Films present improved photosensitivity and optical contrast, good resistance to photofatigue, and high spatial resolution. These photochromic films work as a multifunctional, dynamic photosensitive material with a real-time image recording feature. PMID:26864876

  9. 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.

  10. Development of environmentally friendly piezoelectric polymer film actuator having multilayer structure

    NASA Astrophysics Data System (ADS)

    Tajitsu, Yoshiro

    2016-04-01

    We designed a new soft piezoelectric polymer actuator with a multilayer structure using the environmentally friendly polymer poly(lactic acid) (PLA). PLA is a chiral polymer having two isomers. One is poly(l-lactide) (PLLA) and the other is poly(d-lactide) (PDLA). PLLA and PDLA exhibit piezoelectric constants with opposite signs owing to their chirality. On the basis of their piezoelectric characteristics, we were able to realize a PDLA and PLLA multilayer film (PDLA/PLLA multilayer) with a simple structure. The PDLA/PLLA multilayer film of centimeter-order size exhibited a large piezoelectric resonance and its piezoelectric performance was equivalent to that of a practical piezoelectric ceramic. In this paper, as a first step toward realizing a new film actuator using the PDLA/PLLA multilayer film, we introduce the piezoelectric characteristics of a PLLA film and the concept of an actuation system using a PLLA film. Next, the fabrication process of the PDLA/PLLA multilayer film and its piezoelectric characteristics are summarized. Finally, typical examples of developed piezoelectric polymer actuation systems using a PDLA/PLLA multilayer film are described to demonstrate the potential application of piezoelectric polymer actuation systems.

  11. 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. PMID:11640959

  12. 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).

  13. 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.

  14. Mechanothermally induced conformational switch of a porphyrin dimer in a polymer film.

    PubMed

    Doan, Hung; Raut, Sangram L; Yale, David; Balaz, Milan; Dzyuba, Sergei V; Gryczynski, Zygmunt

    2016-07-21

    Stretching a polymer film induces a conformational change (from the twisted to planar state) in the embedded porphyrin dimer, as evidenced by steady-state and time-resolved emission spectra. PMID:27294828

  15. 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

  16. 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).

  17. 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. PMID:18642154

  18. 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.

  19. Photoluminescence quenching in a polymer thin-film field-effect luministor

    NASA Astrophysics Data System (ADS)

    Dyreklev, P.; Inganas, O.; Paloheimo, J.; Stubb, H.

    1992-03-01

    Photoluminescence quenching is observed in thin films of poly(3-hexylthiophene) and Langmuir-Blodgett films of poly(3-hexylthiophene)/arachidic acid due to the injection of positive charges in the polymer. Charge injection was made in a polymer field-effect transistor. The quenching is discussed in terms of polarons/bipolarons acting as recombination centra for the excitons and suppress the photoluminescence. The inverse phenomenon, luminescence enhancement by depletion of charges, is also achieved.

  20. Soft-shear induced phase-separated nanoparticle string-structures in polymer thin films.

    PubMed

    Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Al-Enizi, Abdullah M; Elzatahry, Ahmed; Berry, Brian C; Karim, Alamgir

    2016-04-12

    Application of shear stress has been shown to unidirectionally orient the microstructures of block copolymers and polymer blends. In the present work, we study the phase separation of a novel nanoparticle (NP)-polymer blend thin film system under shear using a soft-shear dynamic zone annealing (DZA-SS) method. The nanoparticles are densely grafted with polymer chains of chemically dissimilar composition from the matrix polymer, which induces phase separation upon thermal annealing into concentrated nanoparticle domains. We systematically examine the influence of DZA-SS translation speed and thus the effective shear rate on nanoparticle domain elongation and compare this with the counterpart binary polymer blend behavior. Unidirectionally aligned nanoparticle string-domains are fabricated in the presence of soft-shear in confined thin film geometry. We expect this DZA-SS method to be applicable to various NP-polymer blends towards unidirectionally aligned nanoparticle structures, which are important to functional nanoparticle structure fabrication. PMID:26814827

  1. 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.

  2. Fabrication of water-stable organic transistors using crystalline rubrene thin-film and polymer-treated dielectric (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kim, Jaejoon; Lee, Hyoek Moo; Cho, Sung Oh

    2015-10-01

    For the real application of organic electronics, stable operation of electronic devices in humid or aqueous condition is essential and desirable. However, most of organic semiconductors were very weak to the oxygen or water and especially, cannot be operated well in aqueous condition without an encapsulation. Here, we present water-stable organic thin-film transistors with highly crystallized rubrene and polymer-treated dielectrics. These high water-stability could be achieved by two factors. First, rubrene, a well-known p-type semiconducting material, showed high air and water stability after the crystallization of `abrupt heating'. By the fabrication and aqueous operation of rubrene thin film transistor, we could show the water stability of crystallized thin-film rubrene. Such high environmental stability is attributed to the fact that rubrene has comparatively low HOMO level of -5.4 eV and large bandgap energy of 3.2 eV and that the rubrene thin-film is composed of well-interconnected orthorhombic rubrene crystals. Second, the polymer-treatment of dielectrics can enhance long-term water stability of fabricated rubrene thin-film transistor. By the complete immersion test of transistors, we could characterize the increase of water-stability after the treatment of dielectrics with cross-linked polymer. For this purpose, polystyrene is cross-linked by electron irradiation and the water penetration into semiconductor/dielectric interface was decreased due to the decreased surface energy of polymer dielectric compared to the SiO₂. The fabricated rubrene thin-film transistors showed a field-effect mobility of ~0.5 cm2V-1s-1 and long-term stability under ambient and aqueous conditions. Also, we investigated their potential applications in chemical or bio sensors.

  3. 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

  4. Impact of molecular orientation on thermal conduction in linear-chain polymer films

    SciTech Connect

    Kurabayashi, K.; Goodson, K.E.

    1999-07-01

    Polymer films are serving as passive regions in fast logic circuits and as active regions in organic optoelectronic devices, such as light-emitting diodes. Recent data illustrated the strong anisotropy in the thermal conductivity of polyimide films of thickness near one micrometer, with the in-plane value larger by a factor of approximately five. This manuscript extends previous theoretical work on heat conduction in stretched bulk polymers to model the conductivity anisotropy in linear-chain polymer films. Predictions are based on the standard deviation of the angle of molecular orientation with respect to the film in-plane direction, which can be investigated using birefringence data, and the expected conductivity anisotropy in a material with perfectly-aligned strands. The modeling and previous data indicate that the anisotropy factor could increase to a value larger than 10 for polyimide films much thinner than 1 micrometer.

  5. Nanoporous thin-film membranes from block-polymers : using self-consistent field theory calculations to guide polymer synthesis.

    SciTech Connect

    Cordaro, Joseph Gabriel

    2010-12-01

    The controlled self-assembly of polymer thin-films into ordered domains has attracted significant academic and industrial interest. Most work has focused on controlling domain size and morphology through modification of the polymer block-lengths, n, and the Flory-Huggins interaction parameter, {chi}. Models, such as Self-Consistent Field Theory (SCFT), have been successful in describing the experimentally observed morphology of phase-separated polymers. We have developed a computational method which uses SCFT calculations as a predictive tool in order to guide our polymer synthesis. Armed with this capability, we have the ability to select {chi} and then search for an ideal value of n such that a desired morphology is the most thermodynamically favorable. This approach enables us to synthesize new block-polymers with the exactly segment lengths that will undergo self-assembly to the desired morphology. As proof-of-principle we have used our model to predict the gyroidal domain for various block lengths using a fixed {chi} value. To validate our computational model, we have synthesized a series of block-copolymers in which only the total molecular length changes. All of these materials have a predicted thermodynamically favorable gyroidal morphology based on the results of our SCFT calculations. Thin-films of these polymers are cast and annealed in order to equilibrate the structure. Final characterization of the polymer thin-film morphology has been performed. The accuracy of our calculations compared to experimental results is discussed. Extension of this predictive ability to tri-block polymer systems and the implications to making functionalizable nanoporous membranes will be discussed.

  6. 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).

  7. 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.

  8. Interfacial interactions of poly(ether ketone ketone) polymer coatings onto oxide-free phosphate films on an aluminum surface

    SciTech Connect

    Asunskis, A. L.; Sherwood, P. M. A.

    2007-07-15

    This article continues a series of papers that shows how thin (10 nm or less) oxide-free phosphate films can be formed on a number of metals. The films formed have potential as corrosion resistant films. Previous papers have shown that it is possible to extend the range of the surface coatings that can be formed by placing a thin polymer layer over the phosphate layer. In this work it is shown how the water insoluble polymer poly(ether ketone ketone) (PEKK) can be placed over a thin oxide-free phosphate film on aluminum metal. The surface and the interfaces involved were studied by valence band and core level x-ray photoelectron spectroscopy. Difference spectra in the valence band region were used to show that there is a chemical interaction between the PEKK and phosphate thin films on the aluminum metal. Three different phosphate film compositions were studied using different phosphorous containing acids, H{sub 3}PO{sub 4}, H{sub 3}PO{sub 3}, and H{sub 3}PO{sub 2}. This type of interaction illustrates the potential of phosphates to act as adhesion promoters. The valence band spectra are interpreted by calculations.

  9. 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.

  10. 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.

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

    PubMed

    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

  12. 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

  13. Conformation-triggered flow instability in monolayer thick polymer films

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Beers, Kathryn; Matyjaszewski, Krzysztof; Rubinstein, Michael; Dobrynin, Andrey

    2005-03-01

    Here we have report on a new type of flow instability triggered by conformational changes of brush-like macromolecules as they spread on a solid substrate. By tracing the movement of individual molecules by atomic force microscopy, we were able to follow the evolution of the instability pattern on the molecular level enabling a microscopic understanding of the underlying physical mechanism. The instability is an analog of the Saffman-Taylor instability in thin films. However, the instability is driven by a variation in flow velocity controlled by molecular conformation instead of a viscosity gradient.

  14. Gain properties of dye-doped polymer thin films

    NASA Astrophysics Data System (ADS)

    Gozhyk, I.; Boudreau, M.; Haghighi, H. Rabbani; Djellali, N.; Forget, S.; Chénais, S.; Ulysse, C.; Brosseau, A.; Pansu, R.; Audibert, J.-F.; Gauvin, S.; Zyss, J.; Lebental, M.

    2015-12-01

    Hybrid pumping appears as a promising compromise in order to reach the much coveted goal of an electrically pumped organic laser. In such configuration the organic material is optically pumped by an electrically pumped inorganic device on a chip. This engineering solution requires therefore an optimization of the organic gain medium under optical pumping. Here, we report a detailed study of the gain features of dye-doped polymer thin films. In particular we introduce the gain efficiency K , in order to facilitate comparison between different materials and experimental conditions. The gain efficiency was measured with a variety of experimental methods (pump-probe amplification, variable stripe length method, laser thresholds) in order to study several factors which modify the actual gain of a layer, namely the confinement factor, the pump polarization, the molecular anisotropy, and the re-absorption. For instance, for a 600-nm-thick 5-wt % DCM doped poly(methyl methacrylate) (PMMA) layer, the different experimental approaches give a consistent value of K ≃ 80 -cm MW-1 . On the contrary, the usual model predicting the gain from the characteristics of the material leads to an overestimation by two orders of magnitude, which raises a serious problem in the design of actual devices. In this context, we demonstrate the feasibility to infer the gain efficiency from the laser threshold of well-calibrated devices. Temporal measurements at the picosecond scale were carried out to support the analysis.

  15. Subdiffraction-Resolution Optical Measurements of Molecular Transport in Thin Polymer Films.

    PubMed

    Pahal, Suman; Raichur, Ashok M; Varma, Manoj M

    2016-06-01

    The measurement of molecular transport within polymer films yields information about the internal structural organization of the films and is useful in applications such as the design of polymeric capsules for drug delivery. Layer-by-layer assembly of polyelectrolyte multilayer films has been widely used in such applications where the multilayer structure often exhibits anisotropic transport resulting in different diffusivities in the lateral (parallel to the film) and transverse (normal to the film) directions. Although lateral transport can be probed using techniques such as fluorescence recovery after photobleaching (FRAP), it cannot be applied to probing transverse diffusivity in polymer films smaller than the diffraction limit of light. Here we present a technique to probe the transport of molecules tagged with fluorphores in polymer films thinner than the optical diffraction limit using the modulation of fluorescence emission depending on the distance of the tagged molecules from a metal surface. We have used this technique to probe the diffusion of proteins biotin and bovine serum albumin (BSA) in polyelectrolyte multilayer films. We also studied the interdiffusion of chains in multilayer films using this technique. We observed a 3 order of magnitude increase in interdiffusion as a function of the ionic strength of the medium. This technique, along with FRAP, will be useful in studying anisotropic transport in polymer films, even those thinner than the diffraction limit, because the signal in this technique arises only from transverse and not lateral transport. Finally, this technique is also applicable to studying the diffusion of chromophore-labeled species within a polymer film. We demonstrate this aspect by measuring the transverse diffusion of methylene blue in the PAH-PAA multilayer system. PMID:27175850

  16. Gelatin/hydroxypropyl methylcellulose matrices - Polymer interactions approach for oral disintegrating films.

    PubMed

    Tedesco, Marcela P; Monaco-Lourenço, Carla A; Carvalho, Rosemary A

    2016-12-01

    Oral disintegrating film represents an optimal alternative for delivery system of active compounds. The choice of film-forming polymer is the first step in the development of oral disintegrating films and the knowledge of molecular interactions in this matrix is fundamental to advance in this area. Therefore, this study aimed to characterize gelatin and hydroxypropyl methylcellulose (HPMC) films and their blends as matrices of oral disintegrating films. The films were produced by casting technique and were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, mechanical properties, contact angle, time disintegration and bioadhesive strength. Differential scanning calorimetry showed that enthalpy of fusion and melting temperatures of the blends films were lower than those of the gelatin film, which may be associated with the lack of intra-chain interactions also observed in the Fourier transform infrared spectra. In blends, a less compact cross-section structure was observed in scanning electron microscopy images compared with isolated polymer films. The addition of HPMC increased the elongation, hydrophilicity and in vitro bioadhesive force and decreased in vitro disintegration time, important properties in the development of oral disintegrating films. Although the mixture of the polymers showed no synergistic behavior, this study may contribute to the development of new applications for polymeric matrices in the pharmaceutical industry. PMID:27612760

  17. The Film Formation of Polymer Particles in Drying Thin Films of Aqueous Acrylic Latices.

    PubMed

    van Tent A; te Nijenhuis K

    2000-12-15

    The aim of this study is to determine the factors that contribute to the process of film formation of binder particles in drying aqueous dispersion coatings, based on acrylic polymers. It is known that concentrated latices of uniform size show iridescent, colored light patterns. These colors are caused by interparticle interference, and they are only present when the latex particles are ordered in a regular structure. The interparticle interference can be characterized by measuring the transmission as a function of wavelength of the incident light. It appeared that the changes of the interparticle interference of a drying latex film can be related to changes in the interparticle distance and displacement. It was also found that the interparticle distance becomes "negative" upon coalescence of the latex particles. This means that from this point on, the change in interparticle interference is directly related to the indentation or deformation of the latex particles. It became clear that the coalescence process differs from deformation mechanisms accepted in the literature. It seems that the deformation of the particles follows a biaxial mechanism. This means that the particles deform only in one direction, perpendicular to the film surface. Copyright 2000 Academic Press. PMID:11097771

  18. Mechanical testing and characterization of PVDF, a thin film piezoelectric polymer

    SciTech Connect

    Vinogradov, A.M.; Holloway, F.

    1997-10-01

    Mechanical properties of the thin film piezoelectric polymer PVDF are examined experimentally. The developed program comprising static, creep and dynamic (oscillatory) tests provides a consistent empirical data base for material characterization of the polymer: The results of the study indicate that PVDF thin films are orthotropic materials. The constitutive equations of linear hereditary viscoelasticity are shown to accurately represent the time-dependent response of PVDF over a wide range of stresses, temperatures and frequencies. The experiments indicate that the polymer exhibits thermorheologically simple behavior governed by the temperature-frequency correspondence principle.

  19. POLYMER FILM STANDARDS FOR X-RAY FLUORESCENCE SPECTROMETERS (JOURNAL VERSION)

    EPA Science Inventory

    Sets of thin polymer films were developed to serve as standards for XRF analysis of the following 18 elements in aerosol particle samples: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Rb, Sr, Zr, Cd, Sb, Ba, and Pb. Each film contains a pair of elements having non-interfering x-ray...

  20. 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. PMID:27254136

  1. Microstructural and electrical properties of CoCl2 doped HPMC/PVP polymer blend films

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    Solid polymer electrolyte (SPE) based on Hydroxypropylemethylcellulose (HPMC) and Polyvinylpyrrolidone (PVP) polymer blend films complexed with different weight ratio of CoCl2 were prepared using solution casting method and investigated using X-ray line profile analysis. An attempt has been made to study the changes in crystal imperfection parameters in HPMC/PVP blend films with the increase in concentration of CoCl2. 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 conductivity measurements in these films show that the conductivity increases as the concentration of CoCl2 increases. These films were suitable for electro chemical applications.

  2. 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.

  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%. PMID:24734656

  4. p-type conduction in sputtered indium oxide films

    SciTech Connect

    Stankiewicz, Jolanta; Alcala, Rafael; Villuendas, Francisco

    2010-05-10

    We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.

  5. Co-assembly of polymer covered cyclic peptide nanotubes and block copolymer in thin films

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Lazzara, Thomas; Li, Changyi; Helmes, Brett; Xu, Ting

    2013-03-01

    Nanotubular structures have gained prevalent interest for their unique hollow structures and high aspect ratio and their potential applications ranging from molecular separation to nanocomposite membranes. We used nanotube forming cyclic peptide (CP) as the structural motif and studied the self-assembly of polymer conjugated CPs in block copolymer (BCP) matrix in thin films. The co-assembly process is mainly driven by thermodynamic quantities, namely Flory-Huggins polymer-polymer interactions that governs the interaction between CP and BCP, interfacial interactions that affects polymer chain orientation, and thin film commensurability. In addition, due to the dynamic nature of the nanotube formation, the co-assembly process is also pathway-dependent. Thus, processing conditions are critical in co-assembling CP nanotubes and BCP in thin films. Our result shows that the initial aggregation state of polymer covered CP nanotubes determines the pathway the system takes and hence the final morphology of the films. The co-assembly of polymer-conjugated CPs and BCPs demonstrates the feasibility of assembling 1D nanotubes in supramolecular thin films and opens up a new avenue for the generation of novel nanotubular structures.

  6. Stability of ultrathin nanocomposite polymer films controlled by the embedding of gold nanoparticles.

    PubMed

    Amarandei, George; Clancy, Ian; O'Dwyer, Colm; Arshak, Arousian; Corcoran, David

    2014-12-10

    Thin and ultrathin polymer films combined with nanoparticles (NPs) are of significant interest as they are used in a host of industrial applications. In this paper we describe the stability of such films (hpoly ≤ 30 nm) to dewetting, specifically, how the development of a spinodal instability in a composite NP-polymer layer is controlled by the embedding of Au NPs. At working temperatures (T = 170 °C) above the polymer glass transition temperature (Tg ≈ 100 °C) the absence of Au NPs leads to film rupture by nucleation dewetting, while their presence over a large surface area enhances the development of a spinodal instability without destroying the film continuity. When the NPs embed, the surface undulations are suppressed. The dynamics change from an unstable to a stable state, and the thin composite NP-polymer layer returns to a flat configuration, while the wavelength of the pattern remains constant. Moreover, we demonstrate from a thermodynamic perspective that NPs will remain on the surface or embed in the polymer film depending on their free energy, which is determined by the NP interactions with the underlying polymer, the native SiOx layer, and the Si substrate. PMID:25491070

  7. Spreading of Polymer Films at the Molecular Scale: Conformation, Orientation, and Fractionation.

    NASA Astrophysics Data System (ADS)

    Barrett, Michael; Nese, Alper; Matyjaszewski, Krzysztof; Sheiko, Sergei

    2009-03-01

    Previously, we have reported that comb-like polymer macromolecules undergo a plug-flow with an insignificant contribution of molecular diffusion (Phys. Rev. Lett. 93, 206103, 2004). It was also suggested that the composition of the flowing polymer melt was the same both inside the fluid reservoir (drop) and in the precursor film. This work called into question the macroscopic picture of polymer spreading. Through molecular imaging by AFM, we observe that macromolecules spread at different velocities depending on their size. We show that flow causes the molecules to align perpendicular to the flow direction We have also identified specific molecular conformations, such as hairpins, that become more abundant in spreading films. Lastly, we demonstrate that chain entanglements hinder permeation of long macromolecules from the drop to precursor film. These findings shed light on the molecular mechanism of spreading of polymer melts on natural, i.e. heterogeneous, substrates.

  8. 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

  9. Super gas barrier of transparent polymer-clay multilayer ultrathin films.

    PubMed

    Priolo, Morgan A; Gamboa, Daniel; Holder, Kevin M; Grunlan, Jaime C

    2010-12-01

    Flexible and transparent polymeric "superbarrier" packaging materials have become increasingly important in recent years. Layer-by-layer assembly offers a facile technique for the fabrication of layered, polymer-clay superbarrier thin films. At only 51 nm thick, these nanocomposite thin films, comprised of 12 polymer and 4 clay layers, exhibit an oxygen permeability orders of magnitude lower than EVOH and SiOx. Coupling high flexibility, transparency, and barrier protection, these films are good candidates for a variety packaging applications. PMID:21047123

  10. Change in the waveform of broadband ultrasound reflected back from a sample via a polymer film

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Mukaimine, Shota

    2016-07-01

    This paper deals with the changes in the reflected waveform obtained from a sample after covering the sample with a polymer film. First, a theoretical model to predict the waveform obtained from the sample via the film was developed and the validity of the model was verified by experiments in which the ultrasound was transmitted from water into steel samples via a polymer film. Although the present model is based on plane wave theory, it was confirmed experimentally that the model is applicable for focused ultrasonic transducers.

  11. 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. PMID:26905980

  12. 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)

  13. Stabilization of metal-metal oxide surfaces using electroactive polymer films

    SciTech Connect

    Deng, Z.; Smyrl, W.H.; White, H.S. . Corrosion Research Center)

    1989-08-01

    Charge coupling of the catalyzed reduction of O/sub 2/ on platinized poly(3-methylthiophene) (P(3-MT)) films to the anodic dissolution of Ti is reported. Specifically, the redox polymer with Pt catalyst is used in these studies to mediate electrons generated by Ti dissolution and consumed by O/sub 2/ reduction. Due to the large redox polymer capacity ({ge}55 F/cm/sup 3/) of P(3-MT), these reactions occur at a stable potential approximately equal to the reversible oxidation potential of the polymer. Data presented support the conclusion that O/sub 2/ reduction on the polymer film can replenish polymer charge consumed by metal dissolution, thereby stabilizing the potential of Ti within the passive potential range and minimizing the rate of metal dissolution.

  14. Microstructured Films Formed on Liquid Substrates via Initiated Chemical Vapor Deposition of Cross-Linked Polymers.

    PubMed

    Bradley, Laura C; Gupta, Malancha

    2015-07-28

    We studied the formation of microstructured films at liquid surfaces via vapor phase polymerization of cross-linked polymers. The films were composed of micron-sized coral-like structures that originate at the liquid-vapor interface and extend vertically. The growth mechanism of the microstructures was determined to be simultaneous aggregation of the polymer on the liquid surface and wetting of the liquid on the growing aggregates. We demonstrated that we can increase the height of the microstructures and increase the surface roughness of the films by either decreasing the liquid viscosity or decreasing the polymer deposition rate. Our vapor phase method can be extended to synthesize functional, free-standing copolymer microstructured thin films for potential applications in tissue engineering, electrolyte membranes, and separations. PMID:26176742

  15. Metal-Enhanced Fluorescence: Ultrafast Energy Transfer from Dyes in a Polymer Film to Metal Nanoparticles.

    PubMed

    Lee, Jaebeom; Pang, Yoonsoo

    2016-02-01

    Fluorescence from dye molecules dispersed in thin polymer layers increases by 20-25 times when a silver island film exists beneath the layer. Polymer layers of <100 nm thick cover the silver island film to minimize emission quenching from direct contact and also keep the dye molecules in close proximity to the metal nanosurface for possible fluorescence enhancements by silver island film. We report an ultrafast radiation process of ~400 ps lifetime from the surface plasmons of silver nanoparticles observed in time-resolved fluorescence of rhodamine 6G and DCM in thin polymer films coated on silver island surface. The ultrafast energy transfer and fluorescence from metal nanoparticles might be strongly related to the efficiency of metal-enhanced fluorescence. PMID:27433635

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

    PubMed

    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 (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. PMID:27086735

  17. 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.

  18. Photophysics and photochemistry of xanthene dyes in polymer solutions and films

    SciTech Connect

    Kamat, P.V.; Fox, M.A.

    1984-05-24

    The singlet and triplet lifetimes of erythrosin B and rose bengal, two representative xanthene dyes, are significantly increased by enclosing the dye in a cage of poly(4-vinylpyridine) (PVP). The fluorescence yield, controlled by the rate of intersystem crossing, is also increased by such encapsulation. Parallel effects are observed upon adding the polymer to an ethanolic solution of the xanthene or upon loading the dye into a polymer matrix dispersed on a metal oxide surface. The effect of the polymer on static quenching of the excited dye and the implications of dye-loaded polymer films in solar energy conversion are discussed.

  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. Design of molecularly imprinted conducting polymer protein-sensing films via substrate-dopant binding.

    PubMed

    Komarova, Elena; Aldissi, Matt; Bogomolova, Anastasia

    2015-02-21

    Addressing the challenge of protein biosensing using molecularly imprinted polymers (MIP), we have developed and tested a novel approach to creating sensing conducive polymer films imprinted with a protein substrate, ricin toxin chain A (RTA). Our approach for creating MIP protein sensing films is based on a concept of substrate-guided dopant immobilization with subsequent conducting polymer film formation. In this proof-of-concept work we have tested three macromolecular dopants with strong protein affinity, Ponceau S, Coomassie BB R250 and ι-Carrageenan. The films were formed using sequential interactions of the substrate, dopant and pyrrole, followed by electrochemical polymerization. The films were formed on gold array electrodes allowing for extensive data acquisition. The thickness of the films was optimized to allow for efficient substrate extraction, which was removed by a combination of protease and detergent treatment. The MIP films were tested for substrate rebinding using electrochemical impedance spectroscopy (EIS). The presence of macromolecular dopants was essential for MIP film specificity. Out of three dopants tested, RTA-imprinted polypyrrole films doped with Coomassie BB performed with highest specificity towards detection of RTA with a level of detection (LOD) of 0.1 ng ml(-1). PMID:25574520

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Boundary-induced segregation in nanoscale thin films of athermal polymer blends.

    PubMed

    Teng, Chih-Yu; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2016-05-18

    The surface segregation of binary athermal polymer blends confined in a nanoscale thin film was investigated by dissipative particle dynamics. The polymer blend included linear/linear, star/linear, bottlebrush/linear, and rod-like/linear polymer systems. The segregation was driven by purely entropic effects and two different mechanisms were found. For the linear/linear and star/linear polymer blends, the smaller sized polymers were preferentially segregated to the boundary because their excluded volumes were smaller than those of the matrix polymers. For the bottlebrush/linear and rod-like/linear polymer blends, the polymers with a larger persistent length were preferentially segregated to the boundary because they favored staying in the depletion zone by alignment with the wall. Our simulation outcome was consistent with experimental results and also agreed with theoretical predictions - that is, a surface excess dictated by the chain ends for the branch/linear system. These consequences are of great importance in controlling the homogeneity and surface properties of polymer blend thin films. PMID:27108653

  6. Development of polymer optical waveguide-type alcohol sensor

    NASA Astrophysics Data System (ADS)

    Nagata, Junichi; Honma, Satoshi; Morisawa, Masayuki; Muto, Shinzo

    2008-03-01

    Recently, alcohols such as methanol and ethanol have a wide attention as important fuel in next generation. However, As is known, many alcohols have a toxic and explosive nature. To prevent accidents caused by alcohol, development of a safety and highly sensitive sensor is required strongly. In addition, it is desired to be simple and low-cost. So, in this paper, polymer waveguide-type optical alcohol sensors such as fiber-type and channel waveguide-type have been studied. In these sensor head, refractive index n II of cladding layer was set at slightly larger value than that of core (n I). Therefore, in the state without alcohol, the sensor head operate as a leaky waveguide. On the other hand in the state with alcohol, cladding polymer causes swelling and its refractive index becomes lower than n I in core. Based on this principle, large change in output light intensity occurs and detection of alcohol concentration becomes possible even for vapor phase alcohol. In the experiment using a fiber-type sensor with a core size of 0.25 mm, detection of 1% methanol vapor could easily be obtained. Furthermore, using a channel waveguide-type sensor head with a core size of about 50μm×40μm, large increase in sensitivity was observed.

  7. 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.

  8. A study on the stability of n-type conductive polymer

    NASA Astrophysics Data System (ADS)

    Onoda, M.

    2016-04-01

    Novel n-type conducting polymer, poly (p-methylpyridinium vinylene), PMePyV were synthesized by using the quaternization of poly (p-pyridyl vinylene), PPyV and several regiochemical consequences in this polymer were proposed. The electrical, optical, and electrochemical properties of n-type conductive polymer were observed. In addition, a possibility of a variety of functional applications of n-type conductive polymer was indicated.

  9. 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.

  10. 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.

  11. 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.

  12. 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. PMID

  13. Fundamental Study on Vibration in Edge Face of Piezoelectric Chiral Polymer Film

    NASA Astrophysics Data System (ADS)

    Takarada, Jun; Kataoka, Takuya; Yamamoto, Ken; Nakiri, Takuo; Kato, Atsuko; Yoshida, Tetsuo; Tajitsu, Yoshiro

    2013-09-01

    We evaluate the vibration in the edge face of a poly(L-lactic acid) (PLLA) film from the propagated signal of an ultrasonic wave generated by the excitation force of the edge. Although the excitation area is too small to drive the edge face, the vibration can be measured only using the fixing method that does not suppress the resonance and the equipment with a high signal-to-noise ratio. This is considered to be due to the fact that the theoretically calculated force of the PLLA film is more than 10 times larger than that of a well-known ferroelectric polymer film, poly(vinylidene fluoride). We confirm that the film functions as a resonator and can be applied to a resonated transducer. In spite of the vibration in the edge face of the polymer film, we observe compliant responses to excitations by burst or rectangular waves. The practicality of a resonator can be suggested.

  14. 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. PMID:26087914

  15. The Parametric Study of Focused Laser-Induced Marangoni Dewetting for Patterning Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Singer, Jonathan; Ma, Tianxing; Kooi, Steven; Thomas, Edwin

    Highly-localized focused laser spike (FLaSk) heating of polymer thin films is a resist- and developer-free alternative to 2D laser direct write for creating patterns on the single micron or, by exploiting overlap effects, submicron scale. The massive temporal and spatial thermal gradients and resulting thermal Marangoni stresses generated by FLaSk are an effective means for the directed dewetting and patterning of such films. Here, the general applicability of this technique to glassy amorphous polymer thin film systems is investigated through systematic investigation of film thickness, glass transition temperature, and polymer mobility. The results reveal that the important parameters are the film thickness (coupled to the optical heating effects through anti-reflection coating effects) and the high-temperature polymer melt mobility, allowing for generation of single features with linewidths of down to 1 μm. Further, the introduction of spatial mobility variations by using polymer brushes, bilayers, and microphase separated block copolymers leads to additional profile manipulation effects (i . e . spontaneous 2D pattern generation and flattened top profiles).

  16. Local, real-time measurement of drying films of aqueous polymer solutions using active microrheology.

    PubMed

    Komoda, Yoshiyuki; Leal, L Gary; Squires, Todd M

    2014-05-13

    Oscillatory microdisk rheometry was applied to evaluate the evolution of the viscoelastic properties at the surface of a film of an aqueous solution of poly(vinyl alcohol) (PVA) during drying. The drying rate was measured concurrently, based upon measurements of the variation of film thickness. A fully hydrolyzed PVA solution shows a constant drying rate, while a less hydrolyzed PVA solution exhibits a decreased drying rate in the latter part of the drying process, which occurred at the same time as an increase of the elastic modulus. We suggest that this difference in behavior is a consequence of the fact that both the configuration of the PVA molecule and the strength of interaction with water depend on the degree to which the PVA is hydrolyzed. The polymer concentration at the film surface can be estimated from the measured viscosity at the surface for the fully hydrolyzed PVA solution, and this result then can be compared with two theoretical calculations: one in which the polymer concentration is assumed to remain uniform throughout the film, and the other in which the polymer concentration distribution is determined via a one-dimensional diffusion model. This comparison suggests that the polymer is first concentrated locally near the surface but later in the drying process the distribution of polymer becomes increasingly uniform, possibly due to a spontaneously generated convective flow inside the film. PMID:24725080

  17. Engineering the Crystalline Morphology of Polymer Thin Films at a Molecular Level via Matrix Assisted Pulsed Laser Evaporation

    NASA Astrophysics Data System (ADS)

    Jeong, Hyuncheol; Arnold, Craig; Priestley, Rodney

    2015-03-01

    Controlling the crystalline morphology of polymeric thin films at a molecular level has been increasingly important due to their potential as the active layer in organic electronics. Typically, the crystalline morphology in films is achieved via thermal annealing or melt-crystallization of spin-cast polymers. This approach often leads to a spherulitic morphology where the crystalline lamellae grow in all directions. Here, we introduce an alternative approach to make crystalline polymer films via Matrix Assisted Pulsed Laser Evaporation (MAPLE). Using polyethylene oxide (PEO) as a model polymer, we show that the preferential orientation of polymer crystals can be controlled during the film growth. By laser-ablating a frozen dilute solution of the desired polymer, MAPLE provides a non-destructive means for the deposition of polymer films. Due to the liquid nature of as-deposited polymers confined in nanodroplets, this technique can exploit the substrate effect on the crystal nucleation and growth of nano-confined polymers during the film growth. Mimicking the epitaxial growth of metallic films, this novel polymer deposition technique may enable the engineering of film properties in a way not achievable in bulk.

  18. 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. PMID:26942835

  19. Microstructured polymer films by X-ray lithographic exposure and grafting

    NASA Astrophysics Data System (ADS)

    Gürsel, Selmiye A.; Padeste, Celestino; Solak, Harun H.; Scherer, Günther G.

    2005-07-01

    Recently we reported on a new technique to generate micro- and nanostructured polymer materials by the combination of selective irradiation of polymer substrates with X-rays and subsequent grafting of a second polymer. Here we focus on the spatially defined grafting throughout the thickness of poly(ethylene-alt-tetrafluoroethylene) (ETFE) and poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) films using X-ray irradiation through a metal mask, followed by grafting with styrene. Calculations of the transmission of X-rays through the polymer as a function of the wavelength have revealed that energy deposition within the substrate material, which should control the density of created radicals, can be selected in a wide range. Depending on the used wavelength the radicals are created either near the surface or in the bulk of the sample. First experiments demonstrated spatially defined grafting through a 100 μm thick ETFE film and 25 μm thick FEP film. The achieved graft level depends on the irradiation dose as well as on the grafting parameters such as concentration, temperature and time. The precision of structure definition within the film depends on the properties of the X-ray source, the metal mask and the grafting process. The presented process allows controlled grafting through fluoropolymer films with micrometer resolution and local modification of the properties of the films, such as ion conductivity, diffusion of specific molecules or optical properties.

  20. Tackiness of acrylic and cellulosic polymer films used in the coating of solid dosage forms.

    PubMed

    Wesseling, M; Kuppler, F; Bodmeier, R

    1999-01-01

    The objective was to determine the tackiness of acrylic and cellulosic polymer films in order to make predictions on the tackiness (agglomeration) of coated dosage forms during coating and curing. Force-displacement curves of the detachment process of two polymeric films were used as a measure of tackiness. Various polymers (cellulosic (Aquacoat and acrylics (Eudragit RS 30D, L 30D, NE 30D)), plasticizers (triacetin, triethyl citrate, tributyl citrate, acetyltributyl citrate) and anti-tacking agents (talc and glyceryl monostearate) were investigated. The order of tackiness for films prepared from the different aqueous polymer dispersions was in order of Eudragit NE 30D > RS 30D > RL 30D > Aquacoat. The tackiness increased with increasing plasticizer concentration due to the softening of the polymer. A correlation between the minimum film formation temperature and the tackiness was observed, however, no correlation between the tackiness and the lipophilicity of the plasticizer was seen. Talc and glyceryl monostearate (GMS) reduced the tackiness of the films significantly, with GMS being effective at much lower concentrations. Curing of Eudragit RS 30D-coated theophylline beads at temperatures higher than 40 degrees C in an irreversible agglomeration of the beads and damage of the coating upon separation of the beads. This resulted in a faster release than with uncured beads. Blending the beads with talc just prior to the curing step eliminated the agglomeration and therefore film damage, even at a curing temperature of 60 degrees C. PMID:10234529

  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. 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.

  3. 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. PMID:26928813

  4. Langmuir-Schaefer films of a poly(o-anisidine) conducting polymer for sensors and displays

    NASA Astrophysics Data System (ADS)

    Paddeu, Sergio; Ram, Manoj Kumar; Carrara, Sandro; Nicolini, Claudio

    1998-09-01

    Langmuir-Schaefer (LS) films of poly(o-anisidine) (POAS) were fabricated and characterized by means of Brewster-angle microscopy, ellipsometry and electrochemical techniques. The studied optical, cyclic voltammetric and ellipsometric properties of films underlined a regular deposition up to at least 40 monolayers of POAS conducting polymer. The development of surface irregularities beyond 40 monolayers in LS films showed an electrochemical kinetic similar to electrodeposited films. More importantly, the electrochemical kinetic in a small number of monolayers was indicative of the fast transfer process of the electrons. The nature of anions caused meaningful changes in the redox properties of POAS LS films. The electrochromic switching response time and diffusion coefficient of the LS films were estimated through electrochemical surveying. Later, POAS LS films were used as a sensing element for a survey of 0.1 ppm of acid in water through conductimetric measurement.

  5. Pulsed light sintering characteristics of inkjet-printed nanosilver films on a polymer substrate

    NASA Astrophysics Data System (ADS)

    Lee, Dong Jun; Park, Sung Hyeon; Jang, Shin; Kim, Hak Sung; Oh, Je Hoon; Song, Yong Won

    2011-12-01

    In this work, the microstructures of inkjet-printed nanosilver films sintered by intense pulsed light (IPL) were systematically analyzed and correlated with the electrical properties. Nanosilver films with various dimensions were inkjet-printed and sintered at different light intensities to investigate the effects of the film dimension and light intensity on the sintering characteristics. For comparison purposes, the same inkjet-printed films were also thermally sintered at 210 °C for 1 h. Consecutive light pulses from a xenon lamp induced film swelling and the corresponding hollow microstructures of the inkjet nanosilver films. The resistance of IPL-sintered films was inversely proportional to the light intensity, and the resultant conductivity comparable to the thermally sintered one was achieved within just a few tens of ms, without damaging a polymer substrate. While all the thermally sintered patterns experienced shrinkage during the sintering process, the IPL-sintered ones could keep their initial dimension at a certain light intensity.

  6. 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.

  7. Novel nanobubble inflation method for determining the viscoelastic properties of ultrathin polymer films.

    PubMed

    O'Connell, P A; McKenna, G B

    2007-01-01

    We describe a novel experimental technique for measuring the viscoelastic properties of ultrathin polymer films. The method is based on the classic bubble inflation technique for measuring the biaxial creep compliance of films, reduced in size to measure films with thicknesses down to at least 13 nm. The method uses the imaging capabilities of the atomic force microscope to determine the time evolution of the geometry of nanobubbles. Using these data, along with the applied pressure, the absolute creep compliance of the films can be determined. PMID:17503927

  8. Acoustic properties of alumina colloidal/polymer nano-composite film on silicon.

    PubMed

    Zhang, Rui; Cao, Wenwu; Zhou, Qifa; Cha, Jung Hyui; Shung, K Kirk; Huang, Yuhong

    2007-03-01

    Alumina colloidal/polymer composite films on silicon substrates have been successfully fabricated using the sol-gel method, in which the crystallite sizes of alumina are between 20 and 50 nm. The density and ultrasonic phase velocities in these films with different alumina ratios from 14% to 32% were measured at the desired operating frequency. We have proved that the density, acoustic phase velocities, and hence the acoustic impedance of the nano-composite films increase with the alumina content, which gives us another option of tailoring the acoustic impedance of the nano-composite film for making the matching layer of high-frequency medical ultrasonic transducers. PMID:17375816

  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. Low switching voltage ZnO quantum dots doped polymer-dispersed liquid crystal film.

    PubMed

    Hsu, Chuan-Chun; Chen, Yi-Xuan; Li, Hui-Wen; Hsu, Jy-Shan

    2016-04-01

    This paper investigates the effects of ZnO nanoparticles (NPs) on the switching voltages of polymer dispersed liquid crystal (PDLC) films. The threshold and driving electric fields of PDLC film doped with 2.44 wt% ZnO NPs were 0.13 and 0.31 V/μm, respectively, with a contrast ratio of 26. The results of field emission scanning electron microscopy show that the size of the droplets in doped PDLC films increases with the doping concentration. The development of ZnO-doped PDLC films with low driving voltages greatly broadens the applicability of these devices. PMID:27137000

  11. Mechanical Properties of Thin Polymer Films Studied by Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Jerome, Blandine; Vialleton, Christian; Chazeau, Laurent; Charlaix, Elisabeth

    2008-03-01

    Introducing inorganic nanoparticles into a polymer is known to modify the macroscopic mechanical properties of the material. This is often interpreted by assuming the presence of a polymer layer with different properties at the interface with the particles. There is however little direct information available on the mechanical properties of such an interfacial layer. We have used an Atomic Force Microscope (AFM) as a nano-indenter to probe the mechanical response of thin poly(styrene butadiene) random copolymers deposited on oxidized silicon wafers (model silica surface). Indentations were performed at different approach and retraction speeds at room temperature (polymer in the rubbery state) on films with thicknesses ranging from 40nm to 500nm. Approach and retraction curves obtained at high speeds are characteristic of the indentation of an elastic material with an adhesive tip/polymer contact. At low speeds, the adhesion forces dominate for low applied forces, while the elasticity of the polymer dominates the behaviour at high applied load. This allows us to separate the mechanical response of the polymer film from the tip-polymer adhesion that involves some dissipation taking place close to the contact line between the polymer free surface and the tip.

  12. 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.

  13. Confinement Effect on the Effective Viscosity of Plasticized Polymer Films

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Peng, D.; Ogata, Y.; Tanaka, K.; Yang, Z.; Fujii, Y.; Yamada, N. L.; Lam, C. H.; Tsui, Ophelia K. C.

    We have measured the effective viscosity of polystyrene films with a small (4 wt%) added amount of dioctyl phthalate (DOP) deposited on silica. A broad range of molecular weights, Mw, from 13.7 to 2,100 kg/mol was investigated. Our result shows that for the thin films with Mw <~100 kg/mol, the addition of DOP causes the effective viscosity to decrease by a factor of ~4, independent of Mw. But for the higher Mw films, the effective viscosity of the DOP added films creeps towards that of the neat films with increasing Mw. A model assuming the effective viscosity to be dominated by enhanced surface mobility for the lower Mw films, but surface-promoted interfacial slippage for the higher Mw films is able to account for the experimental observations. We are grateful to the support of National Science Foundation through the project DMR-1310536.

  14. High performance NH 3 gas sensor based on ordered conducting polymer ultrathin film

    NASA Astrophysics Data System (ADS)

    Xu, Jianhua; Jiang, Yadong; Yu, Junsheng; Yang, Yajie; Ying, Zhihua

    2008-02-01

    Conducting polymer ultrathin film shows promising future for gas sensor application due to their high conductivity and excellent doping/dedoping performance. In this work, based on an modified Langmuir-Blodgett film method, ultrathin conducting poly(3,4-ethylene dioxythiophene) (PEDOT) film was fabricated. The PEDOT ultathin film was characterized by UV-Vis absorption spectrum, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The results showed small PEDOT grains distributed in polymer LB films after the polymerization of monomer. This ultrathin film exhibited an electrical conductivity about 1.2 Scm -1, and the conductivity increased and decreased to 16.8 and 0.03 Scm -1 after doping and dedoping treatment. The interaction or response of films coated QCM to NH 3 have been tested and it has been found that sensitivity of the composite films on QCM showed better sensitivity than bulk material. To the same analyte concentration, it increased with the increasing number of LB layers coated onto QCMS before 80 layers, and then a decrease of sensitivity of QCM was observed after the layer number exceeded 80 layers. The interaction mechanisms between the ultrathin film and analyte vapor were also included.

  15. 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.

  16. 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. PMID:24370473

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

    NASA Astrophysics Data System (ADS)

    Rebollar, Esther; Vázquez de Aldana, Javier R.; Pérez-Hernández, José A.; Ezquerra, Tiberio A.; Moreno, Pablo; Castillejo, Marta

    2012-01-01

    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.

  18. Precisely Controlled Ultrathin Conjugated Polymer Films for Large Area Transparent Transistors and Highly Sensitive Chemical Sensors.

    PubMed

    Khim, Dongyoon; Ryu, Gi-Seong; Park, Won-Tae; Kim, Hyunchul; Lee, Myungwon; Noh, Yong-Young

    2016-04-01

    A uniform ultrathin polymer film is deposited over a large area with molecularlevel precision by the simple wire-wound bar-coating method. The bar-coated ultrathin films not only exhibit high transparency of up to 90% in the visible wavelength range but also high charge carrier mobility with a high degree of percolation through the uniformly covered polymer nanofibrils. They are capable of realizing highly sensitive multigas sensors and represent the first successful report of ethylene detection using a sensor based on organic field-effect transistors. PMID:26849096

  19. 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.

  20. 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)

  1. 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)

  2. 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.

  3. Self-organization of thin polymer films guided by electrostatic charges on the substrate.

    PubMed

    Zhao, Dan; Martinez, Aaron D; Xi, Xiaolei; Ma, Xinlei; Wu, Ning; Cao, Tingbing

    2011-08-22

    The self-organization of thin polymer films into functional patterns is important both scientifically and technologically. Electric fields have been exploited as an efficient and powerful means to induce the destabilization and self-organization of soft materials. Previous attention, however, has mainly focused on externally applied electric fields. It is shown herein that the internal electric field is strong enough to guide the self-organization of thin polymer films as well. Patterns of electrostatic charges with micrometer resolution are first introduced on a dielectric substrate. A thin polymer film is then spin-coated onto the topographically flat substrate. Upon thermal annealing, the thin polymer film destabilizes due to a lateral gradient of electrostatic stress and flows away from the electroneutral regime to the charged area, resembling the patterns of charges on the substrate. Theoretical and numerical modeling based on the electrohydrodynamic instability shows excellent agreement with experimental observations both qualitatively and quantitatively. It is also demonstrated that the interplay between charge-driven instability with spinodal dewetting and Rayleigh instabilities can generate finer and hierarchical polymeric patterns that are completely different from the charge patterns preintroduced on the substrate. This study provides direct evidence that the internal electric field caused by charges on the substrate is strong enough to destabilize thin polymeric films and generate patterns. This study also demonstrates new strategies for bottom-up fabrication of structured functional materials. PMID:21638784

  4. 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

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

    PubMed

    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

  6. 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.

  7. 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.

  8. Ultrafast large-area micropattern generation in nonabsorbing polymer thin films by pulsed laser diffraction.

    PubMed

    Verma, Ankur; Sharma, Ashutosh; Kulkarni, Giridhar U

    2011-03-21

    An ultrafast, parallel, and beyond-the-master micropatterning technique for ultrathin (30-400 nm) nonabsorbing polymer films by diffraction of laser light through a 2D periodic aperture is reported. The redistribution of laser energy absorbed by the substrate causes self-organization of polymer thin films in the form of wrinklelike surface relief structures caused by localized melting and freezing of the thin film. Unlike conventional laser ablation and laser writing processes, low laser fluence is employed to only passively swell the polymer as a pre-ablative process without loss of material, and without absorption/reaction with incident radiation. Self-organization in the thin polymer film, aided by the diffraction pattern, produces microstructures made up of thin raised lines. These regular microstructures have far more complex morphologies than the mask geometry and very narrow line widths that can be an order of magnitude smaller than the openings in the mask. The microstructure morphology is easily modulated by changing the film thickness, aperture size, and geometry, and by changing the diffraction pattern. PMID:21290600

  9. A bifractal nature of reticular patterns induced by oxygen plasma on polymer films

    NASA Astrophysics Data System (ADS)

    Bae, Junwan; Lee, I. J.

    2015-05-01

    Plasma etching was demonstrated to be a promising tool for generating self-organized nano-patterns on various commercial films. Unfortunately, dynamic scaling approach toward fundamental understanding of the formation and growth of the plasma-induced nano-structure has not always been straightforward. The temporal evolution of self-aligned nano-patterns may often evolve with an additional scale-invariance, which leads to breakdown of the well-established dynamic scaling law. The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films. The reticular pattern, composed of nano-size self-aligned protuberances and underlying structure, develops two types of anomalous dynamic scaling characterized by super-roughening and intrinsic anomalous scaling, respectively. The diffusion and aggregation of short-cleaved chains under the plasma environment are responsible for the regular distribution of the nano-size protuberances. Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise. The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago.

  10. A bifractal nature of reticular patterns induced by oxygen plasma on polymer films

    PubMed Central

    Bae, Junwan; Lee, I. J.

    2015-01-01

    Plasma etching was demonstrated to be a promising tool for generating self-organized nano-patterns on various commercial films. Unfortunately, dynamic scaling approach toward fundamental understanding of the formation and growth of the plasma-induced nano-structure has not always been straightforward. The temporal evolution of self-aligned nano-patterns may often evolve with an additional scale-invariance, which leads to breakdown of the well-established dynamic scaling law. The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films. The reticular pattern, composed of nano-size self-aligned protuberances and underlying structure, develops two types of anomalous dynamic scaling characterized by super-roughening and intrinsic anomalous scaling, respectively. The diffusion and aggregation of short-cleaved chains under the plasma environment are responsible for the regular distribution of the nano-size protuberances. Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise. The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago. PMID:25997075

  11. Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity.

    PubMed

    Gu, Cheng; Huang, Ning; Wu, Yang; Xu, Hong; Jiang, Donglin

    2015-09-21

    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

  12. 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.

  13. 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. PMID:23205620

  14. Measuring spatially distributed rheology of thin polymer films by non-contact shearing

    NASA Astrophysics Data System (ADS)

    Chowdhury, Mithun; Guo, Yunlong; Priestley, Rodney D.

    For nearly two decades, a great detail of research has been devoted to understand the impact of nanoscale confinement on the glassy and viscoelastic properties of thin polymer films. Prior works in supported films mostly used indirect mechano-rhelogical means, due to the complexity associated to probe such small volume. Here we present a non-contact shearing method `blow-off', induced by the laminar flow of an inert gas through a narrow channel in order to generate a well-defined shear stress on a rectangular edge of a properly placed polymer thin film on a solid substrate. By appropriate control of temperature/ time during shearing, we explored effective viscosity and shear mobility, spatially from free surface to the material interior. In general, we found film surface has higher shear mobility and lower effective viscosity in comparison to its interior.

  15. Effects of the Adsorbed Polymer Nanolayers on the Dewetting of Polystyrene Thin Films

    NASA Astrophysics Data System (ADS)

    Cheung, Justin; Wang, Jiaxun; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori

    2015-03-01

    It was previously reported that irreversibly adsorbed polymer nanolayers can be produced on solid substrates by thermal annealing. This study sought to determine the impact of the adsorbed nanolayers on film stability of ultrathin polystyrene (PS) films. A series of bilayers composed of the bottom PS adsorbed nanolayers and PS overlayers with different molecular weights were prepared as model systems. The surface structures of the bilayer films annealed above the bulk glass transition temperature were analyzed by using optical and atomic force microscopes. We will discuss the unique roles of the adsorbed polymer chains in the stability of the liquid thin films. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  16. 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

  17. Direct electrochemical measurements inside a 2000 angstrom thick polymer film by scanning electrochemical microscopy.

    PubMed

    Mirkin, M V; Fan, F R; Bard, A J

    1992-07-17

    An extremely small, conically shaped Pt microelectrode tip (with a radius of 30 nanometers) and the precise positioning capabilities of the scanning electrochemical microscope were used to penetrate a thin (200 nanometers) polymer film and obtain directly the standard potential and kinetic parameters of an electrode reaction within the film. The thickness of the film was determined while it was immersed in and swollen by an electrolyte solution. The film studied was the perfluorosulfonate Nafion containing Os(bpy)(3)(2+) (bpy, 2,2'-bipyridine) cast on an indium tin oxide surface. The steady-state response at the ultramicroelectrode allowed direct determination of the rate constant for heterogeneous electron transfer K(o) and the diffusion coefficient D without complications caused by transport in the liquid phase, charge exchange at the liquid-polymer interface, and resistive drop. PMID:17832832

  18. Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis.

    PubMed

    Bhunia, Susanta Kumar; Nandi, Sukhendu; Shikler, Rafi; Jelinek, Raz

    2016-02-14

    Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e."warm" white light with a high colour rendering index) - a highly sought after goal in optical technologies. PMID:26791813

  19. 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.

  20. Soluble porous coordination polymers by mechanochemistry: from metal-containing films/membranes to active catalysts for aerobic oxidation.

    PubMed

    Zhang, Pengfei; Li, Haiying; Veith, Gabriel M; Dai, Sheng

    2015-01-14

    Soluble porous coordination polymers from mechanochemical synthesis are presented through a coordination polymerization between highly contorted, rigid tetraphenol and a broad variety of transition metal ions. These polymers can be easily cast as metal-containing films or freestanding membranes. Importantly, as-made coordination polymers are highly active and stable in the aerobic oxidation of allylic C-H bonds. PMID:25389070

  1. Capillary levelling in thin polymer films as a nano-rheological tool to probe interface dynamics

    NASA Astrophysics Data System (ADS)

    McGraw, Joshua; Baeumchen, Oliver; Ferrari, Melissa; Fowler, Paul; Dalnoki-Veress, Kari

    2012-02-01

    Entanglement of polymer chains in confinement is modified as a result of altered chain conformations. According to Silberberg's principle, chain segments are reflected at an interface causing a reduction of the inter-chain entanglement density. If the interface is transient, local polymer conformation changes can be inferred from a temporal change in flow properties: over time polymer chains become more entangled, thus there is more resistance to flow. Here, we measure the gradual disappearance of an entropic interface between two melts of identical polymer chains during the flow of stepped bilayer polymer films. Samples are prepared in the glassy state and, when in the melt, flow to relieve the Laplace pressure gradient induced by a step in the topography (McGraw et al., Soft Matter, 2011). Our results reveal the dynamics of re-entanglement across the transient entropic interface.

  2. Physical structure characterization of theophylline in some acidic film-forming polymers.

    PubMed

    Sarisuta, N; Kumpugdee, M; Lawanprasert, P

    2000-06-01

    The physical structure and drug-polymer interactions of theophylline in Eudragit L100, shellac, polyvinyl acetate phthalate (PVAP), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose acetate phthalate (HPMCP), and hydroxypropylmethylcellulose (HPMC) were studied. The drug-polymer films were prepared by casting and were characterized using powder X-ray diffractometry (PXRD), nuclear magnetic resonance (NMR) spectroscopy, and thin-layer chromatography (TLC). Theophylline was found to recrystallize in the modification II form in all kinds of polymers, which was the same as that recrystallized solely from the solvent system and the original powder. The PXRD and NMR results indicated a superficial drug-polymer interaction between theophylline and Eudragit L100, while there was no evidence of interaction for the others. No drug decomposition was observed by TLC for all drug-polymer mixtures. PMID:10826118

  3. Evaluating the effects of plasticizer interactions with HPMC on the tack-behavior of polymer film-forming coating solutions.

    PubMed

    Saringat, Haji Baie; Sheikh, Khalid Ahmad; Khan, Gul Majid

    2004-07-01

    Tack is a concept that is widely used to describe the forces or energies involved in the separation of two parallel surfaces initially in contact through an intervening thin liquid film. The tackiness may cause tablets to stick with each other or to the walls of the coating apparatus. In this study, the HPMC coating solutions were evaluated for their tackiness and the effects of interactions between the polymer and plasticizers on the tack behavior of HPMC film-forming coating solutions were investigated, using type TA-XT2 texture analyzer. It was found that experimental factors such as the contact time, rate of separation and volume of the film-forming test solution could effectively influence the magnitude of tack behavior. Moreover, up to certain levels, the addition of plasticizers such as PEG 400 & 1000 and of triacetin caused a reduction in the tack value of the polymer solutions. It was concluded that in general, the tackiness depended upon the molecular weight and/or type and concentration of a plasticizer. The efficiency of plasticizers used to reduce the tackiness of HPMC solutions ranked as PEG1000 > triacetin > PEG400. PMID:16414595

  4. 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.

  5. 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.

  6. Interaction of Nano-Sized Materials With Polymer Chains in Polymer-Nanocomposite Thin Films-An AFM Perspective

    SciTech Connect

    Verma, Gaurav; Kaushik, Anupama; Ghosh, Anup K.

    2011-12-12

    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.

  7. Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis

    NASA Astrophysics Data System (ADS)

    Bhunia, Susanta Kumar; Nandi, Sukhendu; Shikler, Rafi; Jelinek, Raz

    2016-02-01

    Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e. ``warm'' white light with a high colour rendering index) - a highly sought after goal in optical technologies.Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e. ``warm'' white light with a high colour rendering index) - a highly sought after goal in optical technologies. Electronic supplementary information (ESI

  8. Surface characteristics of a self-polymerized dopamine coating deposited on hydrophobic polymer films.

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhu, Baoku; Xu, Youyi

    2011-12-01

    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. PMID:22011109

  9. Faraday rotation of cobalt ferrite nanoparticle polymer composite films at cryogenic temperatures.

    PubMed

    Demir, Veysi; Gangopadhyay, Palash; Norwood, Robert A; Peyghambarian, Nasser

    2014-04-01

    This paper investigates the behavior of the Verdet constant for cobalt ferrite (CoFe₂O₄) nanoparticles polymer composite films at low temperatures using a 532 nm laser source. An experimental setup for Faraday rotation (FR) at low temperatures is introduced and FRs were measured at various temperatures. Verdet constants were deduced from the paramagnetic model for terbium gallium garnet glass where ~4× improvement was observed at 40° K for CoFe₂O₄ composite film. PMID:24787165

  10. Quantifying residual stress in nanoscale thin polymer films via surface wrinkling.

    PubMed

    Chung, Jun Young; Chastek, Thomas Q; Fasolka, Michael J; Ro, Hyun Wook; Stafford, Christopher M

    2009-04-28

    Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and then trap polymer chains into nonequilibrium stressed conformations. In solvent-cast films, which are central to a wide range of technologies, residual stress can cause detrimental effects, including microscopic defect formation and macroscopic dimensional changes. Since residual stress is difficult to measure accurately, particularly in nanoscale thin polymer films, it remains a challenge to understand and control. We present here a quantitative method of assessing residual stress in polymer thin films by monitoring the onset of strain-induced wrinkling instabilities. Using this approach, we show that thin (>100 nm) polystyrene films prepared via spin-coating possess residual stresses of approximately 30 MPa, close to the crazing and yield stress. In contrast to conventional stress measurement techniques such as wafer curvature, our technique has the resolution to measure residual stress in films as thin as 25 nm. Furthermore, we measure the dissipation of residual stress through two relaxation mechanisms: thermal annealing and plasticizer addition. In quantifying the amount of residual stress in these films, we find that the residual stress gradually decreases with increasing annealing time and plasticizer amounts. Our robust and simple route to measure residual stress adds a key component to the understanding of polymer thin film behavior and will enable identification of more effective processing routes that mitigate the detrimental effects of residual stress. PMID:19298053

  11. Structural and morphological modifications of polymer thin film in the presence of nonsolvent

    NASA Astrophysics Data System (ADS)

    Talukdar, Hrishikesh; Kundu, Sarathi

    2016-05-01

    Thin films of sodium poly(acrylic acid) salt (Na-PAA) have been investigated to obtain the modification of the out-of-plane structure and surface morphology in the presence of toluene which is considered as nonsolvent for Na-PAA. X-ray reflectivity analysis show that the out-of-plane thickness of the Na-PAA film increases if the film is kept for longer time inside the toluene. For the thicker film the effect of toluene is more pronounced than the thinner one. Surface morphology obtained from the atomic force microscopy shows that the top surface becomes relatively rough after the dipping of the Na-PAA film inside toluene. Although toluene is nonsolvent for Na-PAA molecules, however, the effect of restructuring of the nanometer-thick polymer film cannot be ignored. The reason for such structural modification has been proposed.

  12. 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.

  13. 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. PMID:26706528

  14. 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

  15. 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.

  16. 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.

  17. 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. PMID:24771514

  18. Effect of Polymer Confinement on the Film Drainage Behavior- An RICM Study

    NASA Astrophysics Data System (ADS)

    Borkar, Suraj; Ramchandran, Arun

    2015-11-01

    We consider the dynamic effects of confinement of macromolecular liquids on the film drainage process between a drop and a flat surface. Under confinement of the order of few molecular length scales, layering and adsorption of long chains of polymers can cause entropic repulsion due to a reduced configurational freedom. This repulsive force can prevent film rupture and lead to the formation of an equilibrium film. In the current work, experiments were conducted with deformable droplets settling under gravity in a suspending liquid for Bond numbers of O(10-4) . The film drainage was studied using a microinterferometric technique namely, Reflection Interference Contrast Microscopy (RICM) for two different systems: a) silicone oil drops in paraffin oil, b) glycerol drops in silicone oil. The RICM analysis for obtaining the film drainage profiles, was done using a combination of simple cosine theory and ray tracing algorithm. For the silicone oil-paraffin oil system, the film drainage behavior observed was as expected from simulations based on thin film drainage equations. On the other hand, glycerol drops of radii smaller than 130 μm, resulted in the formation of an equilibrium film of silicone oil with an approximate thickness of 10 nm. The origin of this repulsive force is attributed to the presence of an immobilized layer of adsorbed polymer chains. Film drainage observed in glycerol drops of radii larger than 130 μm, was found to destabilize in a non-axisymmetric mode. The rapid growth of this asymmetric instability can lead to stresses (O(100 Pa)) higher than the yield stress of the adsorbed polymer layer.

  19. Influence of selected surfactants on the tackiness of acrylic polymer films.

    PubMed

    Nimkulrat, Sathaporn; Suchiva, Krisda; Phinyocheep, Pranee; Puttipipatkhachorn, Satit

    2004-12-01

    Anti-tacking agents are always necessary in polymeric film coating formulations in order to prevent substrate agglomeration. The objective of this study was to investigate the abilities of certain nonionic surfactants in a group of sorbitan ester in reducing the tackiness of the films obtained from aqueous acrylic polymer dispersions (Eudragit), compared with those of talc and glyceryl monostearate (GMS). The results from the peel tests demonstrated that GMS, Span 60 and Span 40 could significantly reduce the tackiness of both Eudragit NE 30D and Eudragit RS 30D films. The mechanisms in reducing the film tackiness were investigated by analyzing the film compositions, using attenuated total internal reflectance infrared spectroscopy (ATR-IR) and optical microscopy. The storage modulus of the films was also examined. The results indicated that GMS, Span 60, and Span 40 could reduce the film tackiness by decreasing the polymer contents at the film surfaces, resulting in a notable reduction in the contact area of the polymers between the surfaces. The use of only 5% (w/w) of either GMS, Span 60 or Span 40 in the coating formulations is enough to prevent pellet agglomeration without adverse effects on film flexibility. The pellets coated with Eudragit RS 30D/RL 30D (9:1, w/w) did not exhibit any difference in the drug release profiles when either 100% (w/w) talc or 5% (w/w) GMS was used, whereas the formulations containing Span 60 or Span 40 gave a slightly faster release rate. PMID:15541909

  20. High transmittance optical films based on quantum dot doped nanoscale polymer dispersed liquid crystals

    NASA Astrophysics Data System (ADS)

    Gandhi, Sahil Sandesh; Chien, Liang-Chy

    2016-04-01

    We propose a simple way to fabricate highly transparent nanoscale polymer dispersed liquid crystal (nano-PDLC) films between glass substrates and investigate their incident angle dependent optical transmittance properties with both collimated and Lambertian intensity distribution light sources. We also demonstrate that doping nano-PDLC films with 0.1% InP/ZnS core/shell quantum dots (QD) results in a higher optical transmittance. This work lays the foundation for such nanostructured composites to potentially serve as roll-to-roll coatable light extraction or brightness enhancement films in emissive display applications, superior to complex nanocorrugation techniques proposed in the past.

  1. Theoretical considerations of the influence of polymer film coatings on the mechanical strength of tablets.

    PubMed

    Stanley, P; Rowe, R C; Newton, J M

    1981-09-01

    A theoretical analysis of the influence of polymer film coatings on the mechanical strength of tablets has been undertaken. Making some basic assumptions, the theory predicts that neither the thickness of the substrate nor that of the coating has any influence on which fractures first, this being solely determined by the ratio of the tensile fracture strength to the Young's modulus for the two materials. Such a finding suggests that in practice for film-coated tablets the substrate will usually fracture before the coating. Simple measurements of maximum failure loads are of little value in assessing the influence of film coating on the mechanical strength of tablets. PMID:6117631

  2. 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.

  3. 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.

  4. 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.

  5. 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. PMID:26457810

  6. Creating Opal Templated Continuous Conducting Polymer Films with Ultralow Percolation Thresholds Using Thermally Stable Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, D. J.; Kwon, T.; Kim, M. P.; Kim, B. J.; Jung, H.; Bang, J.

    2012-02-01

    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 crosslinked polystyrene (PS) colloidal particles as template. Polymer-coated 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 was found to be 0.20. In contrast, with the addition of an extremely low volume fraction 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.

  7. 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.

  8. Vacuum ellipsometry as a method for probing glass transition in thin polymer films

    NASA Astrophysics Data System (ADS)

    Efremov, Mikhail Yu.; Soofi, Shauheen S.; Kiyanova, Anna V.; Munoz, Claudio J.; Burgardt, Peter; Cerrina, Franco; Nealey, Paul F.

    2008-04-01

    A vacuum ellipsometer has been designed for probing the glass transition in thin supported polymer films. The device is based on the optics of a commercial spectroscopic phase-modulated ellipsometer. A custom-made vacuum chamber evacuated by oil-free pumps, variable temperature optical table, and computer-based data acquisition system was described. The performance of the tool has been demonstrated using 20-200nm thick poly(methyl methacrylate) and polystyrene films coated on silicon substrates at 10-6-10-8torr residual gas pressure. Both polymers show pronounced glass transitions. The difficulties in assigning in the glass transition temperature are discussed with respect to the experimental challenges of the measurements in thin polymer films. It is found that the experimental curves can be significantly affected by a residual gas. This effect manifests itself at lower temperatures as a decreased or even negative apparent thermal coefficient of expansion, and is related to the uptake and desorption of water by the samples during temperature scans. It is also found that an ionization gauge—the standard accessory of any high vacuum system—can cause a number of spurious phenomena including drift in the experimental data, roughening of the polymer surface, and film dewetting.

  9. 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.

  10. 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...

  11. Liposome-containing polymer films and colloidal assemblies towards biomedical applications

    NASA Astrophysics Data System (ADS)

    Teo, Boon M.; Hosta-Rigau, Leticia; Lynge, Martin E.; Städler, Brigitte

    2014-05-01

    Liposomes are important components for biomedical applications. Their unique architecture and versatile nature have made them useful carriers for the delivery of therapeutic cargo. The scope of this minireview is to highlight recent developments of biomimetic liposome-based multicompartmentalized assemblies of polymer thin films and colloidal carriers, and to outline a selection of recent applications of these materials in bionanotechnology.

  12. 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.

  13. 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.

  14. Flexible OLED fabrication with ITO thin film on polymer substrate

    NASA Astrophysics Data System (ADS)

    Kim, Sung Il; Lee, Kyo Woong; Bhusan Sahu, Bibhuti; Geon Han, Jeon

    2015-09-01

    This paper reports the synthesis of flexible indium tin oxide (ITO) films in a dual pulse magnetron sputtering (DPMS) system at low temperature (<100 °C) deposition condition. This study also presents experimental demonstration of the ITO films for their possible use in the fabrication of organic light emitting diode (OLED) device, and the device performance on the super polycarbonate substrates. The presented data reveals the feasibility of ITO films, with a very low sheet resistance of ∼30 Ω/□ and high transmittance of ∼88% at 550 nm, simply by the magnetron pulse mode operations with increasing pulse frequency from 0 to 50 kHz.

  15. Formation of metal nano-particles on and in polymer films investigated by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Rozas, Roberto; Kraska, Thomas

    2007-04-01

    The formation of platinum nano-particles on a polyethylene substrate is investigated by molecular dynamics simulation. As initial configuration, a polymer film is put in contact with a supersaturated platinum vapour. Argon is added in the vapour phase as carrier gas that transfers heat from the vapour phase to the polymer surface. The simulations provide a deep insight into cluster formation at the atomic level. The presence of the polymer affects cluster growth significantly. Surface growth and agglomeration are limited by the polymer matrix. The influence of supersaturation on the cluster size distribution is also different to the particle formation in the gas phase. In addition, the structure of the polymer substrate is modified during the embedding of platinum. These effects are analysed and compared to experimental investigations of the formation of metal-polymer composites. The resulting distribution of metal clusters on the surface and inside the polymer is in general agreement with available experimental results of similar polymer-metal systems.

  16. Characterization of local elastic modulus in confined polymer films via AFM indentation.

    PubMed

    Cheng, Xu; Putz, Karl W; Wood, Charles D; Brinson, L Catherine

    2015-02-01

    The properties of polymers near an interface are altered relative to their bulk value due both to chemical interaction and geometric confinement effects. For the past two decades, the dynamics of polymers in confined geometries (thin polymer film or nanocomposites with high-surface area particles) has been studied in detail, allowing progress to be made toward understanding the origin of the dynamic effects near interfaces. Observations of mechanical property enhancements in polymer nanocomposites have been attributed to similar origins. However, the existing measurement methods of these local mechanical properties have resulted in a variety of conflicting results on the change of mechanical properties of confined polymers. Here, an atomic force microscopy (AFM)-based method is demonstrated that directly measures the mechanical properties of polymers adjacent to a substrate with nanometer resolution. This method allows us to consistently observe the gradient in mechanical properties away from a substrate in various materials systems, and paves the way for a unified understanding of thermodynamic and mechanical response of polymers. This gradient is both longer (up to 170 nm) and of higher magnitude (50% increase) than expected from prior results. Through the use of this technique, we will be better able to understand how to design polymer nanocomposites and polymeric structures at the smallest length scale, which affects the fields of structures, electronics, and healthcare. PMID:25537230

  17. 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.

  18. Three-dimensionally ordered array of air bubbles in a polymer film

    NASA Technical Reports Server (NTRS)

    Srinivasarao, M.; Collings, D.; Philips, A.; Patel, S.; Brown, C. S. (Principal Investigator)

    2001-01-01

    We report the formation of a three-dimensionally ordered array of air bubbles of monodisperse pore size in a polymer film through a templating mechanism based on thermocapillary convection. Dilute solutions of a simple, coil-like polymer in a volatile solvent are cast on a glass slide in the presence of moist air flowing across the surface. Evaporative cooling and the generation of an ordered array of breath figures leads to the formation of multilayers of hexagonally packed water droplets that are preserved in the final, solid polymer film as spherical air bubbles. The dimensions of these bubbles can be controlled simply by changing the velocity of the airflow across the surface. When these three-dimensionally ordered macroporous materials have pore dimensions comparable to the wavelength of visible light, they are of interest as photonic band gaps and optical stop-bands.

  19. Nanoscale structural and mechanical characterization of bamboo-like polymer/silicon nanocomposite films

    NASA Astrophysics Data System (ADS)

    Ni, Hai; Li, Xiaodong; Gao, Hongsheng; Nguyen, Thien-Phap

    2005-09-01

    In an attempt to mimic the bamboo's architecture, bamboo-like polymer/silicon nanocomposites were synthesized by filling silicon nanopores with two conjugated polymers, namely poly(p-phenylene vinylene) (PPV) and its derivative poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene) (MEHPPV). The microstructure, elastic modulus, hardness, nanoscratch resistance, and fracture toughness of the bamboo-like polymer/nanoporous silicon (PS) films were investigated using different functions of an atomic force microscope and nanoindentation techniques. The fracture toughness of MEHPPV- and PPV-filled PS films is 2 and 1.6 times higher than that of PS, respectively, although their elastic modulus and hardness decrease compared to PS. Strengthening and deformation mechanisms are discussed in conjunction with nanocomposite structure, hardness, elastic modulus and nanoscratch resistance.

  20. 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)

  1. Phase Separation of Silicon-Containing Polymer/Polystyrene Blends in Spin-Coated Films.

    PubMed

    Li, Yang; Hu, Kai; Han, Xiao; Yang, Qinyu; Xiong, Yifeng; Bai, Yuhang; Guo, Xu; Cui, Yushuang; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

    2016-04-19

    In this Article, two readily available polymers that contain silicon and have different surface tensions, polydimethylsiloxane (PDMS) and polyphenylsilsequioxane (PPSQ), were used to produce polymer blends with polystyrene (PS). Spin-coated thin films of the polymer blends were treated by O2 reactive-ion etching (RIE). The PS constituent was selectively removed by O2 RIE, whereas the silicon-containing phase remained because of the high etching resistance of silicon. This selective removal of PS substantially enhanced the contrast of the phase separation morphologies for better scanning electron microscope (SEM) and atomic force microscope (AFM) measurements. We investigated the effects of the silicon-containing constituents, polymer blend composition, concentration of the polymer blend solution, surface tension of the substrate, and the spin-coating speed on the ultimate morphologies of phase separation. The average domain size, ranging from 100 nm to 10 μm, was tuned through an interplay of these factors. In addition, the polymer blend film was formed on a pure organic layer, through which the aspect ratio of the phase separation morphologies was further amplified by a selective etching process. The formed nanostructures are compatible with existing nanofabrication techniques for pattern transfer onto substrates. PMID:27052643

  2. 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.

  3. Relaxation of non-equilibrium entanglement networks in thin polymer films

    NASA Astrophysics Data System (ADS)

    Fowler, Paul; McGraw, Joshua; Ferrari, Melissa; Dalnoki-Veress, Kari

    2013-03-01

    It is well established that polymer films, prepared by spincoating, inherit non-equilibrium chain conformations which can affect macroscopic film properties. Here we present the results of crazing measurements that elucidate the non-equilibirum chain configurations in spin-cast films. Furthermore, we find that the entanglement network equilibrates on a time scale comparable to one reptation time. In a second set of experiments, we confine polymers to films with thickness comparable to the molecular size. By stacking two such films at room temperature, a glassy bilayer film with a buried entropic interface is created. According to Silberberg's reflection principle, such an interface has an entropic cost associated with the restricted configurations of molecules that cannot cross the mid-plane of the bilayer. In the melt, the interface heals as chains from the two layers mix and entangle with one another. Crazing measurements reveal that it takes less than one bulk reptation time for a bilayer to become indistinguishable from a single film.

  4. Mechanisms of liquid crystal and biopolymer alignment on highly-oriented polymer thin films

    NASA Astrophysics Data System (ADS)

    Dennis, John Raymond

    1998-12-01

    Molecular order can strongly enhance material properties, or produce materials which perform advanced functions. Many materials, from small crystals to large macromolecules, may be aligned on highly-oriented poly(tetrafluoroethylene) (PTFE) or high-density polyethylene (HDPE) thin films, prepared by a simple shear deposition procedure. Here, processes by which these films produce order are examined, first in a well- characterized liquid crystal, then in two more complex polymer liquid crystals, and finally in an adsorbed motor protein system. Optical second harmonic generation (SHG) was used to study surface molecular order in the liquid crystal 4'-n-octyl-4-cyano-biphenyl (8CB) on PTFE and HDPE films. In nematic 8CB cells with bulk alignment along the polymer orientation axis, the surface monolayers of 8CB were also aligned, and showed C2ν symmetry. In the isotropic phase, the surface monolayer alignment was lost. Monolayers of 8CB evaporated onto either polymer showed little or no alignment. The bulk 8CB alignment appears to be primarily caused by surface ridges through an elastic, bulk- mediated mechanism, unlike the epitaxy-like alignment found on some cloth-rubbed polymer surfaces. For the polymer liquid crystal poly-γ-benzyl- glutamate (PBG), uniform homogeneous surface alignment was observed on PTFE films; this is the first report of PBG surface alignment. However, liquid crystalline samples of microtubules were not aligned. PTFE films show promise for aligning some other polymer liquid crystals via elastic interactions. The motor protein kinesin, adsorbed to PTFE films, transported fluorescently labeled microtubules predominantly in straight lines along the films' orientation axis, not in random directions as observed on glass surfaces. As the kinesin surface density was increased, the degree of alignment peaked and then declined. The results indicate that directed motion occurs because active kinesin preferentially adsorbs to surface sites along linear

  5. Effects of ultra-fast solvent evaporation in solvent vapor annealed cylinder-forming block polymer thin films

    NASA Astrophysics Data System (ADS)

    Baruth, A.; Nelson, G.; Drapes, C.; Wong, J.; Grant, M.

    Despite continued advances in directed self-assembly of block polymer thin films viasolvent vapor annealing, a standardized process remains absent. There remain several complicating factors, notably solvent evaporation rate. Recent theoretical models point to this rate dominating the propagation of a given morphology into the bulk of a thin film following nucleation from the free surface. During this drying process, the film undergoes a competition between thermodynamically driven phase separation and kinetically controlled chain mobility. We, among others, have demonstrated that faster solvent removal can enhance propagation down to the substrate. Perpendicularly aligned cylinders are one illustrative example. To further quantify this effect, and look at ultra-fast time scales, we have constructed a solvent vapor annealing chamber that computer-controls evaporation times down to 15 ms. In situ spectral reflectance, with 10 ms temporal resolution, monitors the swelling and evaporation. We will present results on cylinder-forming polystyrene-block-polylactide thin films swollen to near disorder with tetrahydrofuran, followed by immediate solvent evaporation. Our data reveals control over evaporation times, ranging from 15 ms to several seconds, and the discovery of various evaporation types, previously undetected, including linear, exponential and combinations. Furthermore, atomic force micrographs correlate surface morphologies (both free and substrate) of the resultant films with each evaporation condition. Funded by Nebraska EPSCoR.

  6. 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. PMID:25607497

  7. Polymer Thin Films and Surface Modification by Chemical Vapor Deposition: Recent Progress.

    PubMed

    Chen, Nan; Kim, Do Han; Kovacik, Peter; Sojoudi, Hossein; Wang, Minghui; Gleason, Karen K

    2016-06-01

    Chemical vapor deposition (CVD) polymerization uses vapor phase monomeric reactants to synthesize organic thin films directly on substrates. These thin films are desirable as conformal surface engineering materials and functional layers. The facile tunability of the films and their surface properties allow successful integration of CVD thin films into prototypes for applications in surface modification, device fabrication, and protective films. CVD polymers also bridge microfabrication technology with chemical and biological systems. Robust coatings can be achieved via CVD methods as antifouling, anti-icing, and antihydrate surfaces, as well as stimuli-responsive or biocompatible polymers and novel nanostructures. Use of low-energy input, modest vacuum, and room-temperature substrates renders CVD polymerization compatible with thermally sensitive substrates and devices. Compared with solution-based methods, CVD is particularly useful for insoluble materials, such as electrically conductive polymers and controllably crosslinked networks, and has the potential to reduce environmental, health, and safety impacts associated with solvents. This review discusses the relevant background and selected applications of recent advances by two methods that display and use the high retention of the organic functional groups from their respective monomers, initiated CVD (iCVD) and oxidative CVD (oCVD) polymerization. PMID:27276550

  8. Glass Transition in Thin Supported Polymer Films Probed by Temperature-Modulated Ellipsometry in Vacuum

    NASA Astrophysics Data System (ADS)

    Efremov, Mikhail; Nealey, Paul

    2010-03-01

    Glass transition in model glass-forming polymer coatings is probed by ellipsometry in vacuum. Novel temperature-modulated modification of the technique is used alongside with traditional linear temperature program [1]. Spin-cast 2 - 200 nm thick polystyrene (PS) and 10 - 200 nm thick poly(methyl methacrylate) (PMMA) films on silicon are studied. Measurements are performed at 10-6 - 10-8 torr residual gas pressure. Temperature modulation allows effective separation of reversible glass transition from accompanying irreversible processes. It is found that glass transition in both polymers demonstrates no appreciable dependence on film thickness for more than 20 nm thick coatings. The temperature of the transition (Tg) in thinnest PS films does depend on film thickness, but does not follow often accepted Tg(h)=Tg(∞)[1-(Ah)^δ] function (where h is film thickness, A and δ are constants). Effects of polymer molecular weight and substrate surface pre-treatment on glass transition will be discussed also.[4pt] [1]. M. Yu. Efremov, A. V. Kiyanova, and P. F. Nealey, Macromolecules, 41, 5978 (2008).

  9. Effect of Cooling Rate on Microstructure and Charge Transport in Semiconducting Polymer Thin Films

    NASA Astrophysics Data System (ADS)

    Kang, Evan; Kim, Eunseong; CenterSupersolid; Quantum Matter Research Team

    2011-03-01

    Thermal annealing of polymer thin films often enhances charge carrier mobility which can be attributed to self-healing of the film morphology. We have investigated the effect of cooling rate following the annealing treatment on the thin film microstructure and the charge transport properties using a high performance semiconducting polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). The cooling rate plays a key role in determining the microstructure and performance of polymer thin films. Differential scanning calorimeter measurement shows that fast cooling suppresses the crystallization process. The microstructure of thin films is investigated by using 2D X-ray diffraction and atomic force microscopy. Slow cooling results in well-connected large domains with enhanced three dimensional ordering whereas fast cooling leads to misalignment of small domains with relatively rough surface. Transport characteristics at various temperatures show increase in the charge carrier mobility and decrease in the activation energy when the cooling rate is slowed. This change in the mobility and activation energy becomes saturated with cooling rate below 15 °C/min. E. S. H. K. and E. K. gratefully acknowledge financial support from the National Research Foundation of Korea through the Creative Research Initiatives (CSQR).

  10. 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.

  11. 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.

  12. Versatile Method for Coating Surfaces with Functional and Responsive Polymer-Based Films.

    PubMed

    Zhang, Qiang Matthew; Serpe, Michael J

    2015-12-16

    A versatile surface modification technique was developed to yield poly(N-isopropylacrylamide) (pNIPAm) microgel-based thin films on a variety of substrates, e.g., metals, nonmetals, and polymers. Because the chemistry, and hence functionality and responsivity, of the pNIPAm-based microgels is easily tuned, multifunctional and responsive thin films could be generated on many different surfaces without varying the coating conditions. In one case, we showed that fluorescent/light emitting thin films could be generated using crystal violet-modified microgels. Antibacterial films could be obtained using silver nanoparticle-modified pNIPAm-based microgels. Finally, we show that thin films fabricated via the methods here could be used as a component in optical sensors. Although we show only a few examples of the utility of this approach, we feel that the apparent universality of the technique can be extended to countless other applications. PMID:26640982

  13. Electrochemical quartz crystal microbalance study of redox active C60/Pd polymer films

    NASA Astrophysics Data System (ADS)

    Winkler, K.; Noworyta, K.; Kutner, W.; Balch, A. L.

    2000-11-01

    Properties of conductive C60/Pd polymer films were investigated by simultaneous cyclic voltammetry and piezoelectric microgravimetry at an electrochemical quartz crystal microbalance (EQCM). The films were deposited onto Au electrodes of the EQCM quartz vibrators by concomitant electroreduction of C60 and [PdII(CH3COO)2]3 from a 0.1 M tetra(n-alkyl)ammonium perchlorate [alkyl=ethyl (TEA+), butyl (TBA+) or hexyl (THxA+)], acetonitrile/toluene (1:4, v/v) solution. The composition of this solution significantly influenced the pattern of the film growth. The size of the counter cation is a major factor determining both the electrochemical properties of the C60/Pd films and their stability with respect to dissolution. The fraction of the film reversibly reduced depends mainly on size of the supporting electrolyte cation and increases in the order: THxA+

  14. Multi-length scale porous polymer films from hypercrosslinked breath figure arrays.

    PubMed

    Ding, Lei; Zhang, Aijuan; Li, Wenqing; Bai, Hua; Li, Lei

    2016-01-01

    Multi-length scale porous polymer (MLSPP) films were fabricated using commercially available polystyrene (PS) via static breath figure (BF) process and sequent hypercrosslinking reaction. One level of ordered pores in microscale were introduced using static BF process, and the other level in nanoscale were produced by the sequent Friedel-Crafts hypercrosslinking reaction. The chemical structure of the PS MLSPP film was investigated by Fourier transformation infrared spectrometry and solid state nuclear magnetic resonance, and the morphology of the film was observed with electron microscopes. The MLSPP films showed large specific surface areas and excellent chemical and thermal stabilities, owing to the micropores and the crosslinked chemical structure produced by the Friedel-Crafts reaction. The methodology reported in this paper is a template-free, low cost and general strategy for the preparation of MLSPP films, which has potential applications in the areas of environment and energy. PMID:26397926

  15. The influence of the solid/liquid interface on the dewetting of ultra thin polymer films

    NASA Astrophysics Data System (ADS)

    Lessel, Matthias; Klos, Mischa; Baeumchen, Oliver; Jacobs, Karin

    2012-02-01

    In recent years, many studies showed that a thin liquid film on a solid surface in air bears more complexity than expected from a simple three-layer-system: e.g. a highly mobile surface layer in case the liquid is an unentangled polystyrene (PS) melt (Yang et al., Science 2010; Seemann et al., J. of Polym. Sci. 2006) or the PS melt can slip over the solid substrate (Baeumchen et al., PRL 2009). Our study focuses on such phenomena and explores their influence on dewetting (speed, morphology, etc.). We use hydrophilic and -phobic Si wafer (either covered by a highly ordered silane layer or by a thin layer of an amorphous fluoropolymer, AF 1600). On each of the substrates, one expects for a certain set of parameters spinodal dewetting for the PS melt. Yet experimentally, a much higher hole density is observed for both types of hydrophobic wafers than is theoretically expected. Moreover, the two hydrophobic coatings induce different dewetting speeds: the PS melt dewets faster on the silane covered Si wafer. The difference is attributed to slip (silane) or to no slip (AF 1600) conditions at the PS/substrate interface, which is also observable in the type of liquid front profile, which in turn changes the dewetting morphology.

  16. Electric-field-driven alignment of chiral conductive polymer thin films.

    PubMed

    Tassinari, Francesco; Mathew, Shinto P; Fontanesi, Claudio; Schenetti, Luisa; Naaman, Ron

    2014-04-29

    We investigated the effect of an electric field on the alignment and structural properties of thin films of a chiral polybithiophene-based conductive polymer, functionalized with a protected l-cysteine amino acid. Thin films were obtained by exploiting both drop-casting and spin-coating procedures. The electric properties, the polarized Raman spectrum, the UV-vis spectrum, and the CD spectra were measured as a function of the electric field intensity applied during film formation. It was found that beyond the enhancement of the conductivity observed when the electric field aligns the polymer, the electric field significantly affects the chiral properties and the effect depends on the method of deposition. PMID:24731141

  17. MeV ion beam interaction with polymer films containing cross-linking agents

    SciTech Connect

    Evelyn, A. L.

    1999-06-10

    Polymer films containing cross linking enhancers were irradiated with MeV alpha particles to determine the effects of MeV ion beam interaction on these materials. The contributed effects from the electronic and nuclear stopping powers were separated by irradiating stacked thin films of polyvinyl chloride (PVC), polystyrene (PS) and polyethersulfone (PES). This layered system allowed most of the effects of the electronic energy deposited to be experienced by the first layers and the last layers to receive most of the effects of the nuclear stopping power. RGA, Raman microprobe analysis, RBS and FTIR measured changes in the chemical structures of the irradiated films. The characterization resolved the effects of the stopping powers on the PVC, PS and PES and the results were compared with those from previously studied polymers that did not contain any cross linking agents.

  18. 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.

  19. Ultraviolet irradiation induced polarization restoration in electrically fatigued ferroelectric polymer films

    SciTech Connect

    Fu Shaosong; Hu Jinghang; Zhu Guodong; Yu Hao; Ding Shijin; Jiang Yulong; Cheng Qian

    2013-03-21

    Polarization fatigue is a kind of phenomenon usually observed in most ferroelectric films, which severely degrades the electrical performance of ferroelectric devices. How to restore those degraded polarization as well as how to improve fatigue endurance has been attracting much attention. Here, we report the observation of ultraviolet (UV) irradiation induced polarization restoration in ferroelectric polymer films. Large numbers of experiments indicate that the simultaneous application of UV irradiation and DC bias voltage will result in polarization restoration, which is dependent on both electrical polarity of DC bias and the UV intensity. Repeated fatigue and restoration measurements are also conducted. Based on fatigue mechanism in ferroelectric polymer films, UV-induced restoration is discussed.

  20. Translational Diffusion in Supported Rubberly Polymer Films at Different Layer Thicknesses

    NASA Astrophysics Data System (ADS)

    Pak, Hunkyun; Ellingson, Peter Christopher; Yu, Hyuk

    2002-03-01

    Translational diffusion of an organic dye with C18 hydrocarbon tail (4-octadecylamino-NBD) is examined in thin films of poly(isoprene) and poly(dimethylsiloxane) spincast on substrates. Surface functionalized silicon wafers were used as the substrates. Two kinds of surface functionalized wafers, one with predominantly methyl group and the other with primary amine group, were examined with respect to the diffusion as a function of film thickness over a range of 10-2000 nm. The diffusion coefficient was determined by the technique of fluorescence recovery after photobleaching and the film thickness by ellipsometry. The diffusion coefficient is found to reduce substantially from that in bulk polymers, vary by an order of magnitude over the thickness range, and its dependence is analyzed in terms of a simple model that takes into account of polymer interactions with the functionalized surfaces.

  1. Causes of enhanced boiling heat transfer on surfaces covered with perforated polymer film

    SciTech Connect

    Antonenko, V.A.

    1988-10-01

    Experiments were conducted to determine the causes of enhanced heat transfer on surfaces covered with perforated polymer film and to test a hypothesis for earlier boiling onset on surfaces thus covered. Two experiments were conducted. In the first the heat transfer rates were compared for a paraffin-impregnated Lavsan mesh and the same mesh thinly coated with silver. In the second experiment the comparison was made for a perforated Teflon film and for the same film chemically treated with a sodium-naphthalene complex to improve its wettability. The results show that the main factor leading to enhanced heat transfer on polymer-covered surfaces is the concentration of the heat flux in the perforations. This factor leads to the onset of stable vacuum nucleate boiling at lower heat loads and, hence, lower temperature heads than on bare surfaces. The earlier boiling leads to enhanced heat transfer. Wettability was found to play only a minor part.

  2. 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. PMID:20843521

  3. Effect of an interactive surface on the equilibrium contact angles in bilayer polymer films

    SciTech Connect

    Slep, D.; Asselta, J.; Rafailovich, M.H.; Sokolov, J.; Winesett, D.A.; Smith, A.P.; Ade, H.; Anders, S.

    2000-03-07

    Scanning transmission X-ray microscopy (STXM), atomic force microscopy (AFM), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and photoemission electron microscopy (PEEM) were used to obtain the three-dimensional concentration profiles and the late-stage morphology of liquid bilayer thin films of the two immiscible polymers polystyrene (PS) and (polybromostyrene) (PBr{sub x=0.79}S), where x+ fraction of monomers brominated as a function of the lower PS film thickness. The results could not be explained with existing models developed for bulk viscoelastic fluids. The authors found that, for the case of entangled polymers, other factors such as the interfacial energy with the substrate, the film thickness, and the molecular weights must be considered. A model which includes a restoring force characterizing the change in stiffness of the substrate layer due to surface interactions provided good agreement with the experimental observations.

  4. 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.

  5. 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.

  6. Imaging the Effect of Electrical Breakdown in Multilayer Polymer Capacitor Films

    NASA Astrophysics Data System (ADS)

    Wolak, Mason

    2013-03-01

    Multilayer polymer films show great promise as the dielectric material in high energy density capacitors. Such films show enhancement in both dielectric strength (EB) and energy density (Ud) relative to monolithic films of either source polymer. Composites are typically comprised of alternating layers of a high EB polymer and a high permittivity polymer. Here, we discuss a multilayer system based on polycarbonate (PC) interleaved with polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The dielectric properties of the PC/PVDF-HFP films are influenced by both composition and individual layer thickness. Optimized films show EB = 750 kV/mm and Ud = 13 J/cm3. Further enhancements in EB and Ud are expected through optimization of the component polymers, composition, and layer structure. To guide next generation design, it is important to understand the breakdown mechanism, as it directly influences EB. To elucidate the role of the layer structure during electrical breakdown, we use a tandem focused ion beam (FIB) / scanning electron microscope (SEM) imaging technique. The technique allows us to image the internal layer structure of both `as fabricated' control films, and those subjected to high electric fields. It is therefore a powerful tool to assess film quality and analyze failure mechanisms. Specifically, the FIB is used to mill site-specific holes in a film and the resulting cross-sections are imaged via SEM. Individual layers are easily resolved down to 50 nm. For films subjected to electrical breakdown, the location and propagation of damage is tracked with sequential FIB milling and SEM imaging. Spatially resolved FIB/SEM imaging allows preparation of quasi-3D maps displaying the evolution of internal voids in areas adjacent to the breakdown location (pinhole of d = 30-80 microns). A majority of the voids are localized at the interfaces between layers and may propagate as far as 30-50 microns from the pinhole. The data suggest that the enhancement in

  7. Distance and molecular weight dependence of surface enhanced fluorescence in conjugated polymer thin films

    NASA Astrophysics Data System (ADS)

    Griffo, Michael S.; Carter, Sue A.

    2008-08-01

    Photoluminescence (PL) of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) in the presence of Silver nanoparticles (NP) is studied. The purpose of this research is to understand the PL distance dependence of plasmon-polymer separation and a correlation between the surface enhanced fluorescence (SEF) and polymer molecular weight. Distinct peaks in PL are found for plasmon-polymer separations ranging from near the far field to the near field, under 100 nm. Extinction of the devices shows that changes in absorption cannot explain all enhancement in PL and suggests that a modification of the radiative lifetime is modified. The dependence of the photoluminescence of MEH-PPV on molecular weight shows variation but overall suggests chain length does not affect film quenching. This is largely attributed to the large polydispersity of the polymer materials used.

  8. Electronic transport and Luttinger behavior in polymer thin films in the quasi-atomic limit

    NASA Astrophysics Data System (ADS)

    Szasz, Aaron; Ilan, Roni; Moore, Joel

    Recent experiments have shown two-dimensional polymer films to be promising materials for thermoelectric devices, but some of the observed properties are not well understood. To better understand these materials, we introduce a new model in which each polymer is a Luttinger liquid and the polymers are weakly coupled to each other. This approximation of strong interactions within each polymer and weak coupling between them is the ``quasi-atomic limit.'' We find integral expressions for transport coefficients, including the electrical and thermal conductivities and the thermopower, and we extract their power law dependencies on temperature. Luttinger liquid physics is manifested in a violation of the Wiedemann-Franz law. This research was supported by the AFOSR MURI program.

  9. In vitro study of drug loading on polymer-free oxide films of metallic implants.

    PubMed

    Shih, Chun-Ming; Shih, Chun-Che; Su, Yea-Yang; Chang, Nen-Chung; Lin, Shing-Jong

    2005-12-01

    Traditionally, a drug that is loaded onto a metallic surface has to use various polymer bondings as its platform. Unfortunately, polymer coatings on a metallic surface cause numerous problems after implantation, such as late thrombosis, inflammation, and restenosis. This research was conducted to investigate whether an oxide layer can be used as a polymer-free platform for drug loading, especially for cardiovascular stents. The interaction and loading of heparin onto different oxide films on 316LVM stainless steel wire was confirmed in vitro by experimental studies using linear voltammetry, electrochemical impedance spectroscopy, and electron spectroscopy for chemical analysis. The eluting of heparin from heparinized surface was studied by using high-performance liquid chromatography, and activated clotting time in addition to linear voltammetry and electron spectroscopy for chemical analysis analyses. Experimental results show that amorphous oxide could be a potential substitute for the polymer coating of drug-loaded stents for minimizing metallic corrosion, inflammation, late thrombosis, and restenosis. PMID:16082699

  10. 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.

  11. Polarization anisotropy dynamics for thin films of a conjugated polymer aligned by nanoimprinting

    NASA Astrophysics Data System (ADS)

    Schmid, S. A.; Yim, K. H.; Chang, M. H.; Zheng, Z.; Huck, W. T. S.; Friend, R. H.; Kim, J. S.; Herz, L. M.

    2008-03-01

    Time-integrated and femtosecond time-resolved photoluminescence spectroscopy has been used to study the dynamic emission polarization anisotropy for thin films of a conjugated polymer whose chains had been aligned through a nanoimprinting technique. The results indicate a high degree of chain alignment, with the presence of a small fraction of unaligned chain domains in film regions far from the imprinted surface. The time-averaged emission from aligned domains is found to be slightly shifted to higher photon energies compared to that from more disordered film regions. This effect is attributed to a subtly different chain packing geometry in the more aligned regions of the film, which leads to a reduced exciton diffusivity and inhibits energetic relaxation of the exciton in the inhomogeneously broadened density of states. While for an unaligned reference film, exciton migration results in a nearly complete depolarization of the emission over the first 300 ps, for the aligned films, interchain exciton hopping from unaligned to aligned domains is found to increase the anisotropy over the same time scale. In addition, excitons generated in aligned film domains were found to be slightly more susceptible to nonradiative quenching effects than those in disordered regions deeper inside the film, suggesting a marginally higher defect density near the nanoimprinted surface of the aligned film.

  12. Nanoscale investigation of viscoelasticity in thin polymer films using environmental scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Schmidt, Ronald Henry

    The tribological and rheological behavior of thin polymer films at the nanometer length scale has become a topic of extreme technological and scientific interest. The friction and wear characteristics of ultrathin organic coatings are critical in magnetic storage media devices, as well as emerging technologies such as microelectromechanical devices. In the microelectronics industry, the ability to produce ultrathin coatings of photoresists and electron resists that are free of scratches and thickness fluctuations is a crucial step in any lithography process. Fortunately the need to understand the behavior of ultrathin organic films has coincided with the development of the scanning probe microscope (SPM) which is able to impose shear and tensile forces, and image the resulting deformations, on the nanometer scale. In contrast to traditional scientific disciplines like condensed matter physics and physical chemistry, the "nanoscience" community has only recently begun to examine the role of temperature in material response. This is largely because piezoelectric transducers are incompatible with substantial temperature elevation. A recent advance in SPM design has isolated the transducer and accompanying electronics from the sample, enabling investigators to heat samples to temperatures as high as 170°C without affecting the performance of the instrument. Using an environmental SPM, we examined the temperature and rate dependence of tip-imposed plastic and viscoelastic deformations in thin polymer films. Viscous flow in defects in nonwetting films was investigated as well. Chapter 1 provides a brief review of viscoelastic and plastic deformations in bulk polymers, the glass transition temperature, and the effect of confining polymer molecules to an interface on the observed glass transition temperature. Chapter 2 discusses scanning probe microscopy instrumentation, techniques, and applications to polymer thin film tribology. In Chapters 3 and 4, results are

  13. Elastic properties of protein functionalized nanoporous polymer films

    DOE PAGESBeta

    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

  14. Elastic Properties of Protein Functionalized Nanoporous Polymer Films.

    PubMed

    Wang, Haoyu; Black, Charles T; Akcora, Pinar

    2016-01-12

    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. 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. PMID:26672623

  15. 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.

  16. 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. PMID:24055395

  17. 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.

  18. Peel resistance characterization of localized polymer film bonding via thin film adhesive thermally activated by scanned CO2 laser

    NASA Astrophysics Data System (ADS)

    Dowding, Colin; Dowding, Robert; Griffiths, Jonathan; Lawrence, Jonathan

    2013-06-01

    Thermal laser polymer bonding is a non-contact process for the joining of polymer laminates using thermally activated adhesives. Conventional, contact based bonding techniques suffer from mechanical wear, geometric inflexibility and poor energy efficiency. The application of lasers offers the potential for highly localized delivery of energy and increased process flexibility whilst achieving controlled and repeatable bonding of polymer laminates in a contact free process. Unlike previously reported techniques, here it is reported that laser based non-contact bonding is both viable and highly desirable due to the increased levels of control it affords the user. In this work, laser polymer bonding of 75 μm thick linear low density polyethylene (LLDPE) film backed with a thermally activated adhesive to a 640 μm thick polypropylene (PP) substrate was conducted using continuous wave 10.6 μm laser radiation and scanning galvanometric optics. The effect of laser power and scanning traverse speed on the peel resistance properties of the bonded polymer laminates is presented, with a threshold specific energy density for successful adhesive activation determined.

  19. Efficiency optimization in ionically self-assembled thin film polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Marciu, Daniela; Miller, M.; Ritter, A. L.; Murray, M. A.; Neyman, Patrick J.; Graupner, Wilhelm; Heflin, James R.; Wang, Hong; Gibson, Harry W.; Davis, Rick M.

    2000-04-01

    We present detailed studies of polymer light emitting diodes fabricated from ionically self-assembled monolayer thin films. The ionically self-assembled monolayer (ISAM) films are created with a new thin film fabrication technique that allows detailed structural and thickness control at the molecular level. The ISAM fabrication method simply involves the dipping of a charged substrate alternately into polycationic and polyanionic aqueous solutions at room temperature. Importantly, the ISAM technique yields exceptionally homogeneous, large area films with excellent control of total film thickness. Our studies concentrate on improving the performance of ISAM light emitting diodes that include poly(para-phenylene vinylene) (PPV). The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely manipulated through the parameters of the electrolyte solutions. The effects of the pH and ionic strength of the immersion solutions, the total film thickness, and the PPV thermal conversion parameters on the photoluminescence and electroluminescence yields have been systematically studied. Through the ISAM process we can also deposit well-defined thicknesses of different polymers at the indium tin oxide and aluminum electrode interfaces. The interface layers are found to affect the electroluminescence efficiency.

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

    PubMed

    Ao, Zhimin; Li, Sean

    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

  1. 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

  2. Electrochemical redox properties of polypyrrole/Nafion composite film in a solid polymer electrolyte battery

    SciTech Connect

    Momma, Toshiyuki; Kakuda, Satoko; Yarimizu, Hideki; Osaka, Tetsuya

    1995-06-01

    Nafion{reg_sign} was introduced into a polypyrrole (PPy) matrix, and the redox performance of the PPy/Nafion electrode was investigated in a polyethylene oxide (PEO)-LiClO{sub 4} electrolyte. A rougher interface between polymer cathode and polymer electrolyte is usually needed for an all-solid battery, however, the PPy/Nafion cathode works well regardless of the flat surface of the PPy/Nafion film. When compared to a PPy film doped with ClO{sub 4}{sup {minus}} anions with a similar morphology, the PPy/Nafion film showed better redox performance. The results of the impedance spectroscopy and potential-step chronoamperometry confirmed that the improvement in the redox reaction of the PPy/Nafion film was due to the enhancement of the ion diffusion rate in the film. Thus, the PPy/Nafion film showed good charging-discharging properties in a rechargeable Li/PEO-LiClO{sub 4}/(PPy/Nafion) battery.

  3. Relaxation of non-equilibrium entanglement networks in thin polymer films.

    PubMed

    McGraw, Joshua D; Fowler, Paul D; Ferrari, Melissa L; Dalnoki-Veress, Kari

    2013-01-01

    It is known that polymer films, prepared by spin coating, inherit non-equilibrium configurations which can affect macroscopic film properties. Here we present the results of crazing experiments that support this claim; our measurements indicate that the as-cast chain configurations are strongly stretched as compared to equilibrium Gaussian configurations. The results of our experiments also demonstrate that the entanglement network equilibrates on a time scale comparable to one reptation time. Having established that films can be prepared with an equilibrium entanglement network, we proceed by confining polymers to films in which the thickness is comparable to the molecular size. By stacking two such films, a bilayer is created with a buried entropic interface. Such an interface has no enthalpic cost, only an entropic penalty associated with the restricted configurations of molecules that cannot cross the mid-plane of the bilayer. In the melt, the entropic interface heals as chains from the two layers mix and entangle with one another; crazing measurements allow us to probe the dynamics of two films becoming one. Healing of the entropic interface is found to take less than one bulk reptation time. PMID:23355094

  4. Structure of confined polymer thin films subject to shear

    NASA Astrophysics Data System (ADS)

    Smith, G. S.; Kuhl, T. L.; Hamilton, W. A.; Mulder, D. J.; Satija, S.

    2006-11-01

    Using neutron reflectivity and the newly developed Shear Confinement Cell (SCC), we have directly quantified the density distribution of opposing neutral polymer brushes confined between parallel plates in good solvent conditions. With an average separation between the plates of approximately 1000 Å, our measurements show that the density profile in the overlap region between opposing polymer brushes flattens consistent with predictions from molecular dynamics simulations. A significant increase in density at the anchoring surfaces due to compression of the brush layers is observed. This compression or collapse of the brushes in restricted geometries strongly suggests that high-density brushes do not interpenetrate significantly in good solvent conditions. In addition, for the first time, we have measured the effects of an applied shear stress on the sample. We find that for neutral brushes, shear creates a totally new disentangled structure which surprisingly relaxes only after a time span of a few weeks.

  5. Optical properties of Ag nanoparticle-polymer composite film based on two-dimensional Au nanoparticle array film

    NASA Astrophysics Data System (ADS)

    Wang, Long-De; Zhang, Tong; Zhang, Xiao-Yang; Song, Yuan-Jun; Li, Ruo-Zhou; Zhu, Sheng-Qing

    2014-03-01

    The nanocomposite polyvinyl pyrrolidone (PVP) films containing Ag nanoparticles and Rhodamine 6G are prepared on the two-dimensional distinctive continuous ultrathin gold nanofilms. We investigate the optical properties and the fluorescence properties of silver nanoparticles-PVP polymer composite films influenced by Ag nanoparticles and Au nanoparticles. Absorption spectral analysis suggests that the prominently light absorption in Ag nanowire/PVP and Ag nanowire/PVP/Au film arises from the localized surface plasmon resonance of Ag nanowire and Au nanofilm. The enhanced fluorescence is observed in the presence of Ag nanowire and Au nanofilm, which is attributed to the excitation of surface plasmon polariton resonance of Ag nanowire and Au nanofilm. The gold nanofilm is proven to be very effective fluorescence resonance energy transfer donors. The fabricated novel structure, gold ultrathin continuous nanofilm, possesses high surface plasmon resonance properties and prominent fluorescence enhancement effect. Therefore, the ultrathin continuous gold nanofilm is an active substrate on nanoparticle-enhanced fluorescence.

  6. 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. PMID:20800735

  7. 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. PMID:27432518

  8. Measurement of the mechanical properties of thin film polymers at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Youngquist, R. C.; Gibson, T. L.; Jolley, S. T.; Williams, M. K.

    2014-01-01

    Many applications require specific knowledge of thin film polymeric properties at cryogenic temperatures. In particular, applications in pressure vessels and structural components require understanding of the mechanical properties of polymers. The use of polymeric and composite materials has a strong potential to replace metals and decrease the mass of spacecraft while providing lower thermal conductivity for future space exploration missions. There is limited mechanical property data of thin film polymers available at cryogenic temperatures to evaluate these materials for such applications. In order to quantify material properties such as Young's Modulus and ultimate strength at cryogenic temperatures, a new experimental device has been constructed. This test apparatus uses pressurized liquid nitrogen to deform a polymer film disk and a laser displacement sensor to measure the resulting deformation. In this method, the liquid nitrogen pressure is slowly increased to provide incremental loads for evaluation. Several materials with known bulk modulus at 77 K were tested along with novel materials that are on the cutting edge of polymer science. The test setup and test results are presented here for discussion and further study.

  9. Vitrification of thin polymer films: from linear chain to soft-colloid like behavior

    NASA Astrophysics Data System (ADS)

    Glynos, Emmanouil; Frieberg, Bradley; Sakellariou, Georgios; Chremos, Alexandros; Green, Peter

    2015-03-01

    The glass transition temperature Tg of sufficiently thin, supported, polymer films is dependent on the film thickness. Based on the nature of the polymer substrate interactions Tg may increase, ΔTg >0, or decrease, ΔTg <0, in relation to the bulk. We show that for star-shaped macromolecules the value of ΔTg depends on the functionality f of the molecule, for polymer films supported by the same substrate. Specifically in the case of polystyrene (PS) macromolecules, with arms of molecular weight Marm<10 kg./mol., supported by silicon oxide substrates, ΔTg <0, when f<4. For much higher functionalities, f >= 32, where the polymer exhibits soft-colloid like behavior ΔTg ~ 0. For values of 40. The transition from the linear-chain to the soft-colloid behavior is gradual and occurs with increasing f and/or decreasing Marm. With the help of molecular dynamics simulations we rationalize this behavior in terms of competing entropic effects, associated with changes in f and Marm, which drives the ability of these molecules to efficiently pack at interfaces.

  10. Predicting Themomechanical Responses of Polymer Thin Films and Nanocomposites via an Innovative Coarse-grained Approach

    NASA Astrophysics Data System (ADS)

    Xia, Wenjie; Hsu, David; Keten, Sinan

    Understanding and predicting the thermomechanical responses of nanoscale polymer systems are very challenging as their responses are greatly influenced by many factors, such as interfacial energy, filler volume fraction and molecule weight, giving rise to the presence of nanoscale interface and free surface. To overcome these issues, here we employ a novel atomistically informed coarse-grained computational technique, called thermomechanically consistent coarse graining (TCCG), to investigate how the nanoscale interface and free surface influence the elastic modulus (E) and glass transition temperature (Tg) of polymer films and nanocomposites. By performing tensile tests and nanoindentation simulations, we are able to predict the size dependent elastic properties of polymer films and quantify the length scale of the local mechanical interphase. Finally, taking cellulose nanocrystal (CNC) and poly(methyl-methacrylate) (PMMA) nanocomposites as a relevant model system, we present a multi-scale framework built upon our CG approach to allow the prediction of Tg of nanocomposite as a function of interfacial energy and filler volume fractions by drawing the analogy between thin film and nanocomposites. Our established multi-scale framework is validated by recent experiments and breaks new ground in predicting, without any empirical parameters, key structure-property relationships for polymer nanomaterials.

  11. 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.

  12. 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.

  13. Photo-generated Acid Diffusion in Polymer Photoresist Thin Films

    NASA Astrophysics Data System (ADS)

    Lin, Eric; Soles, Christopher; Wu, Wen-Li; Lin, Qinghuang

    2000-03-01

    Advanced photoresist formulations make use of photosensitive molecules, photoacid generators (PAGs), which decompose to form acids after illumination with UV radiation. The photo-generated acids then catalytically alter the solubility of the resist polymer during a post-exposure bake so that the exposed areas of an image can be removed with an appropriate solvent. One of the limitations in resist performance is the diffusion of small molecules such as the photoacid generators (PAG), photo-generated acids (PGAs), solvents, and performance enhancing additives, in the photoresist formulation. We utilize the high spatial resolution of neutron reflectometry over length scales relevant to line width broadening (10 nm to 20 nm) to measure the diffusion rates of PAGs, PGAs, and polymers in model resist materials. In this study, the model polymer matrix material is monodisperse poly(hydroxystyrene)(PHS) and the photoacid generator is bis(p-tert-butylphenyl) iodonium perfluorooctanesulfonate (PFOS). By measuring the profiles of the PGAs in the PHS layer and into an overlaying poly(methyl methacrylate) layer as a function of post-exposure bake temperature and time, the initial rates of diffusion may be determined.

  14. 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

    2008-12-01

    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. PMID:18991420

  15. 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.

  16. 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.

  17. Silver metal colloidal film on a flexible polymer substrate

    NASA Astrophysics Data System (ADS)

    del Rocío Balaguera Gelves, Marcia; El Burai-Félix, Alia; De La Cruz-Montoya, Edwin; Jeréz Rozo, Jaqueline I.; Hernández-Rivera, Samuel P.

    2006-05-01

    A method to prepare metallic nanoparticles films in the presence of a hydrophilic copolymer with the aim of inhibiting the formation of clusters in the nanoparticles has been developed. Thin films prepared could be used in applications such as sensors development and substrates for surface-enhanced Raman spectroscopy. The synthesis of colloidal solutions of silver nanoparticles was achieved by the reduction AgNO 3 using sodium citrate with thermal treatment which results in a robust fabrication of gold and silver films. The polymeric films were prepared by polymerization 2-hydroxyethyl methacrylate with methacrylic acid (method 1). The other procedure employed (method 2) incorporated the use of polyvinyl pyrrolidone and polyethylene glycol as copolymers. A scanning electron microscope was used to provide microstructural information of coverage achieved. The ability to tune the nanocoating structure and spectral and electronic properties can be used for applications such as sensors used in the detection of explosives. Silver nanoparticles were also characterized by surface-enhanced Raman scattering (SERS), which integrates high chemical sensitivity with spectroscopic identification and has enormous potential for applications involving ultra-sensitive chemical detection. Spectra were obtained using a Renishaw RM2000 Raman Microspectrometer system operating in the visible region excitation (532 nm).

  18. 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.

  19. Applications of Fourier Transform Raman spectroscopy to studies of thin polymer films

    SciTech Connect

    Zimba, C.G.; Hallmark, V.M.; Turrell, S.; Swalen, J.D.; Rabolt, J.F. )

    1990-01-25

    Raman spectroscopic studies of submicron-thick films have been accomplished through the use of integrated optical techniques. By using the film as an asymmetric slab waveguide for the laser excitation, and collecting the scattering emanating from the guided streak, the authors have obtained Raman spectra of organic films, polymer laminates, and molecular composites. The utility of the waveguide Raman spectroscopy technique has been limited by high levels of fluorescence when visible wavelength excitation is used. With the advent of FT-Raman spectroscopy, in which a near-infrared laser is used, Raman spectra of highly fluorescent and intensely colored materials could be easily obtained. In this study, waveguide Raman spectroscopic measurements using near-infrared excitation and a Michelson interferometer have been demonstrated. The use of a fiber optic bundle to collect the scattering and convert the image from a line to a circle has resulted in a 15-fold improvement over conventional lens collection. With the improved sensitivity, FT-Raman spectra of films containing small molecule chromophores imbedded in a polymer matrix have been obtained. In addition, extension of this method to polymers of low refractive index, by using a sublayer of very low refractive index material, such as MgF{sub 2}, has been outlined.

  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. 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

  2. Optimization of Ferroelectric Polymer ∖Graphene Films for Transparent and Flexible Electronics

    NASA Astrophysics Data System (ADS)

    Kahya, Orhan; Wu, Jing; Ni, Guang-Xin; Toh, Chee-Tat; Bae, Sang-Hoon; Ahn, Jong-Hyun; Oezyilmaz, Barbaros

    2013-03-01

    Nonvolatile, electrostatic doping of graphene-based devices with ferroelectric polymers such as Poly (vinylidene fluoride-trifluoroethylene) are promising for realizing ultra-fast, flexible memory devices, nanogenerators and actuators. More recently, the same approach has been shown to provide an alternative route in enabling graphene based transparent electrodes for touch screen applications. Here, we report a systematic study of optimizing the ferroelectric polymer-graphene heterostructure as a function of thickness, various copolymer blends and coating techniques. Optimized films show outstanding mechanical properties, low sheet resistance (~ 100 Ω/sq) and optical transparency levels as high as 96%.

  3. Flat polymer electrolytes promise thin-film power. Technical report, July 1988-June 1989

    SciTech Connect

    Zafar, M.; Munshi, A.; Owens, B.B.

    1989-06-15

    In laboratories all around the world, scientist and engineers are working on a new solid-state battery that could be fabricated much thinner than 100 micrometers. The battery uses a solid polymer electrolyte as the ionically conducting medium, instead of a liquid electrolyte. Flat cells have been available for several years and have been incorporated into devices such as the Polaroid instant-film pack. However, these have been modifications of conventional liquid-electrolyte cell designs. Recent innovations in solid-state batteries that use lithium anodes, solid cathodes, and a solid polymer electrolyte that both separates and provides the ionic pathway between the anode and cathode.

  4. 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

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

    NASA Astrophysics Data System (ADS)

    Hsu, Yu-Jen

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

  6. Broadband All-Polymer Phototransistors with Nanostructured Bulk Heterojunction Layers of NIR-Sensing n-Type and Visible Light-Sensing p-Type Polymers

    PubMed Central

    Han, Hyemi; Nam, Sungho; Seo, Jooyeok; Lee, Chulyeon; Kim, Hwajeong; Bradley, Donal D. C.; Ha, Chang-Sik; Kim, Youngkyoo

    2015-01-01

    We report ‘broadband light-sensing’ all-polymer phototransistors with the nanostructured bulk heterojunction (BHJ) layers of visible (VIS) light-sensing electron-donating (p-type) polymer and near infrared (NIR) light-sensing electron-accepting (n-type) polymer. Poly[{2,5-bis-(2-ethylhexyl)-3,6-bis-(thien-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-diyl}-co-{2,2′-(2,1,3-benzothiadiazole)]-5,5′-diyl}] (PEHTPPD-BT), which is synthesized via Suzuki coupling and employed as the n-type polymer, shows strong optical absorption in the NIR region (up to 1100 nm) in the presence of weak absorption in the VIS range (400 ~ 600 nm). To strengthen the VIS absorption, poly(3-hexylthiophene) (P3HT) is introduced as the p-type polymer. All-polymer phototransistors with the BHJ (P3HT:PEHTPPD-BT) layers, featuring a peculiar nano-domain morphology, exhibit typical p-type transistor characteristics and efficiently detect broadband (VIS ~ NIR) lights. The maximum corrected responsivity (without contribution of dark current) reaches up to 85 ~ 88% (VIS) and 26 ~ 40% (NIR) of theoretical responsivity. The charge separation process between P3HT and PEHTPPD-BT components in the highest occupied molecular orbital is proposed as a major working mechanism for the effective NIR sensing. PMID:26563576

  7. Effects of polymer side chains on the self-assembling of conjugated polymer in thin film

    NASA Astrophysics Data System (ADS)

    Jiang, Yunfei; Wang, Yiqing; Bunz, Uvw H. F.; Perahia, Dvora

    2006-03-01

    Conjugated polymers are inherently semi-conducting and optically active materials, with immense potential applications in organic electro-optical devices. The chemical structure of the polymer including the rigidity of the backbone and the nature of substituents affect their association as well as their electro-optical response. The following work reports the effects of different side chains on the structure and fluorescence of highly conjugated polymer, poly(para phenyleneethynylene) (PPE). When substituted by long polylactide side chains they self-assemble into wires with fingerprint-like arrangement, casting from chloroform solutions on oxidized silicon wafer. With increasing content of poor solvent, the dimension of the structures increased and then crystallized area appeared, as showed in AFM studies. The introducing of the long flexible polymer side chains has significantly reduced the stacking between rigid backbones. This in tern results in a frequency shift in their fluoresces response, indication changes in the electronic levels. Direct measurements of the electronic levels using ATM are currently in progress.

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

    PubMed

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

    2013-08-01

    The deviations of the glass transition temperature (T(g)) in thin films of an amorphous conjugated polymer poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) are reported. Monotonic and nonmonotonic T(g) 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 T(g) 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. PMID:24032856

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

    PubMed Central

    Moazzez, Behrang; O'Brien, Stacey M.; Merschrod S., Erika F.

    2013-01-01

    We present and analyze a method to improve the morphology and mechanical properties of gold thin films for use in optical sensors or other settings where good adhesion of gold to a substrate is of importance and where controlled topography/roughness is key. To improve the adhesion of thermally evaporated gold thin films, we introduce a gold deposition step on SU-8 photoresist prior to UV exposure but after the pre-bake step of SU-8 processing. Shrinkage and distribution of residual stresses, which occur during cross-linking of the SU-8 polymer layer in the post-exposure baking step, are responsible for the higher adhesion of the top gold film to the post-deposition cured SU-8 sublayer. The SU-8 underlayer can also be used to tune the resulting gold film morphology. Our promoter-free protocol is easily integrated with existing sensor microfabrication processes. PMID:23760086

  10. Evaluation of the film-coating properties of a hydroxyethyl cellulose/hydroxypropyl methylcellulose polymer system.

    PubMed

    Li, Shun Por; Martellucci, Stephen A; Bruce, Richard D; Kinyon, Adam C; Hay, Michael B; Higgins, John D

    2002-04-01

    The effect of different grades of hydroxyethyl cellulose (HEC) and hydroxypropyl methllcellulose (HPMC) on the film-formation and taste-masking ability for ibuprofen granules was evaluated. Three batches of coated ibuprofen granules were prepared using a roto-granulator, each with a different coating composition. Two grades of HEC [MW300,000 (H) and MW90,000 (L)] were combined with three different grades of HPMC [MW 11,000 (L), MW 25,000 (M) and MW 35,000 (H)] to prepare the coating solutions. Mechanical strength and physical properties of the polymer films were evaluated. Films made from HPMC (L)/HEC (H), HPMC (M)/HEC (H), and HPMC (H)/HEC (H) were stronger and more flexible than the HPMC (L) HEC (L) films. The assay, dissolution, particle size distribution, and environmental scanning electron microscopy (ESEM) data of the three batches of the coated ibuprofen granules were similar. PMID:12056532

  11. New transmission-type X-ray filters consisting of amorphous multilayer films.

    PubMed

    Takagi, Y; Imafuku, M

    1998-05-01

    New transmission-type X-ray filters have been developed. The filters consist of X-ray-amorphous metal (less than 30 A)/metalloid ( approximately 10 A) multilayer films sputter-deposited on X-ray-transparent polymer substrates. Such metal/metalloid multilayer films show only very broad diffraction peaks, since the metal and metalloid layers forming the multilayer films are usually X-ray amorphous if the layers are sufficiently thin. The filters use the wavelength-dependent absorption phenomena near absorption edges of elements to reduce the intensity of transmitted X-rays, without generating any crystalline sharp peaks which cause serious problems in experiments such as fluorescence XAFS measurements. The multilayer-film filters were prepared by a multi-target magnetron sputtering deposition technique, paying special attention to the homogeneity of the layer thickness by spinning substrates of the films. The filters are useful in reducing the intensity of undesirable fluorescence emissions and improving the signal-to-background ratios of data acquired in various measurements using a solid-state detector. PMID:15263592

  12. Effect of gaseous void on bipolar charge transport in layered polymer film

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    This paper describes a hybrid algorithm to study the effect of a gaseous void on bipolar charge transport in layered polymer film. This hybrid algorithm uses a source distribution technique based on an axisymmetric boundary integral equation method to solve the Poisson equation and a fourth order Runge-Kutta (RK4) method with an upwind scheme for time integration. Iterative stability is assured by satisfying the Courant-Friedrichs-Levy stability criterion. Dynamic charge mapping is achieved by allowing conducting and insulating boundaries and material interfaces to be represented by equivalent free and bound charge distributions that collectively satisfy all local and far-field conditions. This hybrid technique caters to bipolar charge injection, field-dependent mobility transport, recombination, and trapping/de-trapping in the bulk and at material and physical interfaces. The resulting charge map is the taxonomy of the different charge types and their abundance, and presents a dynamic view of the temporal and spatial distributions. The paper is motivated by images of breakdown experiments that point to the role of gaseous void in delamination growth. For the test configuration, the high field at the edge of the gaseous void act as a sink first for positive and then negative charge. The net effect is to increase delamination stress at the edge leading to further growth of the defect and increasing the potential for partial discharge within the void.

  13. Structure and interaction of polymer thin films with supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Sirard, Stephen Michael

    2003-06-01

    An understanding of colloid stability in CO2 as well as the interaction of CO2 with polymer thin films is necessary for the intelligent design of CO2-based processes for future materials applications. In-situ spectroscopic ellipsometry (SE) was used to measure the thickness and optical properties of nanoscale poly(dimethylsiloxane) (PDMS) and poly(methyl methacrylate) films exposed to compressed CO2 . Both the sorption and CO2-induced dilation of the thin films were measured simultaneously with SE and deviations between the thin films and the corresponding bulk films may be attributed to excess CO 2 at the free interface as well as the influence of film confinement and the compressible nature of CO2 on the orientation and mobility of the polymers. SE was also used to measure sorption equilibrium and kinetics and CO2-induced dilation of polyimide (6FDA-DAM:DABA 2:1) thin films to determine how a gas separation membrane's structure affects its susceptibility to CO2-induced plasticization. Both thermal annealing and chemical crosslinking reduced the polymer dilation to prevent large increases in the CO2 diffusion coefficient at high CO2 pressures. The CO2 permeability and polymer free volume strongly depend on the annealing temperature, and different effects are observed for the crosslinked and uncrosslinked membranes and for the thick and thin membranes. Neutron reflectivity (NR) and SE were used to characterize the structure of end-grafted d-PDMS brushes on SiOx wafers exposed to compressed CO2. NR revealed two distinct regions in the segment density profile as a function of distance from the surface. The thickness and volume fraction profiles for the brush change much more with solvent quality than has been seen in previous studies with incompressible solvents, due to the high asymmetry in the intermolecular interactions, as well as the large compressibility and free volume differences between the polymer segments and the solvent. Turbidity versus time measurements

  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

    2016-03-01

    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. Photorefractivity in polymer-stabilized liquid crystals films.

    SciTech Connect

    Wasielewski, M. R.

    1998-05-08

    We have shown that PSLCs are capable of forming photorefractive gratings that operate in the thick grating regime. Polymer stabilization alters the charge transport and trapping characteristics of LCs, resulting in longer lived gratings, while maintaining the advantages of high orientational birefringence within LCs. Furthermore, very low applied electric fields (800 V/cm) and low optical intensities (100 mW/cm{sup 2}) are required to create large photorefractive effects in these materials. It is expected that optimization of the redox potentials of the chromophores within the PSLCs will continue to improve the performance of these materials.

  16. Diffracting holographic lenses created on azo-polymer films

    NASA Astrophysics Data System (ADS)

    Sabat, Ribal Georges

    2014-02-01

    Various superimposed chirped relief gratings, acting as diffracting holographic lenses, were photo-inscribed on azopolymer films upon exposure to the interference pattern of a plane and a curved laser light wavefronts. Depending on the configuration used, this resulted in incident light being focused independently of polarization along the 0th or 1st diffracted order of the grating. The focal point and focalization angle of the resulting holographic lenses were easily tuned during the fabrication process.

  17. Capillary Wave Dynamics of Thin Polymer Films over Submerged Nanostructures

    SciTech Connect

    Alvine, Kyle J.; Dai, Yeling; Ro, Hyun W.; Narayanan, Suresh; Sandy, Alec; Soles, Christopher L.; Shpyrko, Oleg G.

    2012-11-13

    The surface dynamics of thin molten polystyrene films supported by nanoscale periodic silicon line-space gratings were investigated with x-ray photon correlation spectroscopy. Surface dynamics over these nanostructures exhibit high directional anisotropy above certain length scales, as compared to surface dynamics over flat substrates. A cutoff length scale in the dynamics perpendicular to the grooves is observed. This marks a transition from standard over-damped capillary wave behavior to suppressed dynamics due to substrate interactions.

  18. 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.

  19. 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.

  20. Photoembossing of surface relief structures in polymer films for biomedical applications.

    PubMed

    Hughes-Brittain, Nanayaa F; Qiu, Lin; Wang, Wen; Peijs, Ton; Bastiaansen, Cees W M

    2014-02-01

    Photoembossing is a technique used to create relief structures using a patterned contact photo-mask exposure and a thermal development step. Typically, the photopolymer consists of a polymer binder and a monomer in a 1/1 ratio together with a photo-initiator, which results in a solid and non-tacky material at room temperature. Here, new mixtures for photoembossing are presented which are potentially biocompatible. Poly(methyl methacrylate) is used as a polymer binder and two different acrylate monomers trimethylolpropane ethoxylate triacrylate (TPETA) and dipentaerythritol penta-/hexa-acrylate (DPPHA) are tested. PMMA-TPETA had a higher surface relief features. Biocompatibility is evaluated by culturing human umbilical vein endothelial cells (HUVECs) on films of these photopolymer blends. PMMA with TPETA and PMMA-DPPHA films showed enhanced cell adhesion compared to PMMA. The cells also showed alignment on surface textured films with the highest degree of alignment on films with 20 μm pitch and 2 μm height. This study shows that photoembossing is a feasible method to produce surface textures on films that can be adopted in the field of tissue engineering to promote cell adhesion and alignment. PMID:23908051

  1. 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. PMID:26491321

  2. 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

  3. A double-sided electret polymer film-based electrostatic actuator

    NASA Astrophysics Data System (ADS)

    Ko, Wen-Ching; Chen, Jia-Lun; Wu, Wen-Jong; Lee, Chih-Kung

    2008-03-01

    A solution made from blending cycloolefin copolymer (COC) and polystyrene (PS) was proposed to create a double-sided electret polymer film. This electret polymer was then sandwiched to form an electret-metal-electret structure by using the MEMS processes. The upper and lower polymer layers were found to both enhance charge storage capacity significantly and to improve the machining property. It was identified that lower concentration of PS led to sphere-like morphology distributed uniformly within the COC/PS blends, which created better electret properties than that of pure COC or pure PS polymers. In addition, it was also found that these COC/PS blends have better adhesion to both metal and polymers. A series of processes developed to optimize this line of new electret polymers for actuator development are detailed. The recipe of this new material and the associated fabricating process to develop an electret loudspeaker are also detailed. In comparison, the pros and cons of this speaker system versus a typical electrostatic loudspeaker or a headphone, which require both bulky and expensive DC-to-DC converters, are detailed as well.

  4. A Novel Mechanochromic and Photochromic Polymer Film: When Rhodamine Joins Polyurethane.

    PubMed

    Wang, Zhijian; Ma, Zhiyong; Wang, Yao; Xu, Zejun; Luo, Yiyang; Wei, Yen; Jia, Xinru

    2015-11-01

    A rhodamine-based molecule, Rh-OH, is synthesized. Rh-OH exhibits a reversible mechanochromic luminescent character but a passivating response to UV light. An elastomeric polymer film based on polyurethane with embedded Rh-OH is prepared via a polycondensation reaction. The film shows mechanochromic and photochromic properties with reversible color change, which originates from the isomerization of the Rh-OH molecule from a twisted spirolactam in the ring-closed form to a planarized zwitterionic structure in the ring-open state. PMID:26402516

  5. 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.

  6. Nonlinear photoinduced anisotropy and modifiable optical image display in a bacteriorhodopsin/polymer composite film

    NASA Astrophysics Data System (ADS)

    Wei, Lai; Luo, Jia; Zhu, Jiang; Lu, Ming; Zhao, You-yuan; Ma, De-wang; Ding, Jian-dong

    2007-04-01

    The nonlinear photoinduced anisotropy with large birefringence in a bacteriorhodopsin/polymer composite (bR/PC) film was observed. The contrast ratio, a ratio of the maximum to the minimum intensity of transmitted probe light through the bR/PC film within the linear gray scale range could reach ˜350:1. An all-optical image display in different colors was performed. The intensity of the transmitted signal could be modulated by adjusting the multibeam polarization states and intensities. Therefore, the positive image, negative image, and image erasure in display were demonstrated.

  7. Fabrication of superhydrophobic polymer films with hierarchical silver microbowl array structures.

    PubMed

    Xu, Miaojun; Lu, Nan; Qi, Dianpeng; Xu, Hongbo; Wang, Yandong; Shi, Shoulei; Chi, Lifeng

    2011-08-01

    Flexible superhydrophobic polyvinyl alcohol (PVA) films with silver bowl-like array structure are fabricated based on the thermal evaporation with sphere monolayer as templates and the modification of 1H, 1H, 2H, 2H-perfluorodecanethiol on silver surface. The silver microbowl arrays were composed of silver nanoparticles with an average diameter size of ca. 10 nm. The polymer films exhibit excellent stability and remarkable superhydrophobicity with a high water contact angle (CA) of about 163° and a low sliding angle (SA) of less than 3°. PMID:21549389

  8. Structure dependence of lasing action in organic polymer films on DFB gratings for dinitrotoluene vapor detection.

    PubMed

    Liu, Qiufeng; Qiu, Keqiang; He, Shengnan; Liu, Honglin; Liu, Zhengkun; Hong, Yilin; Fu, Shaojun

    2016-06-20

    Structure effects of distributed feedback (DFB) gratings on lasing action have been investigated for detecting explosive vapors. For the first time, we have established the optimized profiles of the DFB grating, and given the theoretical path to design its structure for amplified spontaneous emission (ASE) of organic polymer films based on Bragg conditions. A poly(p-phenylene ethynylene) (PPE) film can realize detection of dinitrotoluene (DNT) vapors in 2 min with a reduced excitation threshold of 26 mJ cm(-2) by using a simple and common 405 nm laser. PMID:27277339

  9. Indigo Carmine Dye-Polymer Nanocomposite Films For Optical Limiting Applications

    NASA Astrophysics Data System (ADS)

    Sreeja, S.; Mayadevi, S.; Suresh, S. R.; Frobel, P. G. Louie; Smijesh, N.; Philip, Reji; Muneera, C. I.

    2011-10-01

    Nanocomposite films of an organic dye-polymer (Indigo Carmine-PVA) system were fabricated and their optical limiting behaviour was investigated under excitation with 532 nm laser pulses of 5 ns temporal width using the open aperture Z-scan technique. The samples displayed optical limiting behavior under the experimental conditions. The Atomic Force Microscopic (AFM) analysis of the surface topography revealed homogeneous distribution of nanoclustered aggregates grown within the polymer matrix and an average roughness of ˜2.02 nm for the surface. The estimated values of the effective nonlinear absorption coefficient, βeff (˜10-7-10-8 cm/W) marked up to the highest reported ones in literature in the nanosecond regime. The results indicate that these nanocomposite films are potential materials for optical limiting devices used for the protection of human eyes and other delicate optical sensors from laser induced optical damage.

  10. Exploiting cellular convection in a thick liquid layer to pattern a thin polymer film

    NASA Astrophysics Data System (ADS)

    Nejati, Iman; Dietzel, Mathias; Hardt, Steffen

    2016-02-01

    A method to shape thin polymer films into periodic array of lenses is presented. A liquid layer placed on top of a much thinner polymer film is exposed to a transverse temperature gradient. The upper liquid layer undergoes the short-wavelength Bénard-Marangoni instability, which leads to periodic shear stresses at the liquid-liquid interface and corresponding interfacial deformations. The structures formed are solidified by curing with ultraviolet light. In comparison to previously reported single-layer patterning techniques, the presented method achieves structures of very high horizontal planform symmetry (highly ordered structures). Furthermore, other shapes of technical interest can be easily fabricated by engineering the temperature distribution at the liquid-gas interface.

  11. Light induced conch-shaped relief in an azo-polymer film

    NASA Astrophysics Data System (ADS)

    Watabe, Mizuki; Juman, Guzhaliayi; Miyamoto, Katsuhiko; Omatsu, Takashige

    2014-03-01

    We have discovered that a novel chiral structured surface relief (termed `conch'-shaped surface relief) with a height of over 1 μm can be formed in an azo-polymer film merely by employing circularly polarized optical vortex irradiation with a total angular momentum of j = +/-2. The temporal evolution of the conch-shaped surface relief in the azo-polymer film was also observed. The results provide physical insight into how the angular momentum of light is transferred to a material through mass transport by cis-trans photo-isomerization. Such conch-shaped surface reliefs with chirality, in which functional chemical composites can be doped, enable new applications, such as planar chiral metamaterials, plasmonic holograms, and identification of chiral chemical composites.

  12. Light induced conch-shaped relief in an azo-polymer film.

    PubMed

    Watabe, Mizuki; Juman, Guzhaliayi; Miyamoto, Katsuhiko; Omatsu, Takashige

    2014-01-01

    We have discovered that a novel chiral structured surface relief (termed 'conch'-shaped surface relief) with a height of over 1 μm can be formed in an azo-polymer film merely by employing circularly polarized optical vortex irradiation with a total angular momentum of j = ±2. The temporal evolution of the conch-shaped surface relief in the azo-polymer film was also observed. The results provide physical insight into how the angular momentum of light is transferred to a material through mass transport by cis-trans photo-isomerization. Such conch-shaped surface reliefs with chirality, in which functional chemical composites can be doped, enable new applications, such as planar chiral metamaterials, plasmonic holograms, and identification of chiral chemical composites. PMID:24603295

  13. Light induced conch-shaped relief in an azo-polymer film

    PubMed Central

    Watabe, Mizuki; Juman, Guzhaliayi; Miyamoto, Katsuhiko; Omatsu, Takashige

    2014-01-01

    We have discovered that a novel chiral structured surface relief (termed ‘conch'-shaped surface relief) with a height of over 1 μm can be formed in an azo-polymer film merely by employing circularly polarized optical vortex irradiation with a total angular momentum of j = ±2. The temporal evolution of the conch-shaped surface relief in the azo-polymer film was also observed. The results provide physical insight into how the angular momentum of light is transferred to a material through mass transport by cis-trans photo-isomerization. Such conch-shaped surface reliefs with chirality, in which functional chemical composites can be doped, enable new applications, such as planar chiral metamaterials, plasmonic holograms, and identification of chiral chemical composites. PMID:24603295

  14. Linear dichroism and optical anisotropy of silver nanoprisms in polymer films

    NASA Astrophysics Data System (ADS)

    Requena, S.; Doan, H.; Raut, S.; D’Achille, A.; Gryczynski, Z.; Gryczynski, I.; Strzhemechny, Y. M.

    2016-08-01

    We present optical studies of two different size distributions of silver triangular nanoprisms, one with a dipole resonance at 520 nm and the other with a dipole resonance at 650 nm, placed in different media. Significant wavelength-dependent depolarization of scattered light from the silver nanoprisms suspended in water indicates strong interference of multiple surface plasmon resonant modes in the same particle. We use this depolarization as a probe of light scattering by the nanoprisms in a lipid solution due to the rejection of a polarized background scattering. Also, the silver nanoprisms were embedded in a polyvinyl alcohol polymer matrix and oriented by stretching the polymer/nanoprism nanocomposite films. We observe significantly increased linear dichroism in the region associated with the plasmonic in-plane dipole mode upon stretching. Additionally, there is a weaker linear dichroism in the region associated with out-of-plane modes, which vanish in the extinction spectrum of the stretched nanocomposite film.

  15. Direct immobilization of antibodies on a new polymer film for fabricating an electrochemical impedance immunosensor.

    PubMed

    Zhang, Xiangyang; Shen, Guangyu; Shen, Youming; Yin, Dan; Zhang, Chunxiang

    2015-09-15

    A new polymer bearing aldehyde groups was designed and synthesized by grafting 4-pyridinecarboxaldehyde onto poly(epichlorohydrin). Antibodies can be directly immobilized on the surface of the polymer film through the covalent bonding of aldehyde groups of the film with amino groups of antibodies. In this study, human immunoglobulin G (IgG) was used as a model analyte for the fabrication of an electrochemical impedance immunosensor. Using the proposed immunosensor, IgG in the range from 0.1 to 80 ng ml(-1) was detected with a detection limit of 0.07 ng ml(-1) (signal/noise [S/N]=3). In addition, the electrochemical impedance immunosensor displays good stability and reproducibility. PMID:26072006

  16. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    NASA Astrophysics Data System (ADS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-03-01

    This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films.

  17. The frequency-dependent directivity of a planar fabry-perot polymer film ultrasound sensor.

    PubMed

    Cox, Benjamin T; Beard, Paul C

    2007-02-01

    A model of the frequency-dependent directivity of a planar, optically-addressed, Fabry-Perot (FP), polymer film ultrasound sensor is described and validated against experimental directivity measurements made over a frequency range of 1 to 15 MHz and angles from normal incidence to 80 degrees. The model may be used, for example, as a predictive tool to improve sensor design, or to provide a noise-free response function that could be deconvolved from sound-field measurements in order to improve accuracy in high-frequency metrology and imaging applications. The specific question of whether effective element sizes as small as the optical-diffraction limit can be achieved was investigated. For a polymer film sensor with a FP cavity of thickness d, the minimum effective element radius was found to be about 0.9 d, and that an illumination spot radius of less than d/4 is required to achieve it. PMID:17328336

  18. Improving information density in ferroelectric polymer films by using nanoimprinted gratings

    NASA Astrophysics Data System (ADS)

    Martínez-Tong, Daniel E.; Soccio, Michela; Rueda, Daniel R.; Nogales, Aurora; García-Gutiérrez, Mari Cruz; Ezquerra, Tiberio A.

    2015-03-01

    The development of polymer non-volatile memories depends on the effective fabrication of devices with high density of information. Well-defined low aspect ratio nanogratings on thin films of poly(vinylidene fluoride-trifluoroethylene) copolymers can be fabricated by using Nanoimprint Lithography (NIL). By using these nanogratings, an improved management of writing and reading information can be reached as revealed by Piezoresponse Force Microscopy (PFM). Structural investigation by means of Grazing Incidence X-ray (GIX) scattering techniques indicates that the physical confinement generated by nanoimprint promotes the development of smaller and edge-on oriented crystals. Our results evidence that one-dimensional nanostructuring can be a straightforward approach to improve the control of the polarization in ferroelectric polymer thin films.

  19. Scanning probe microscopy for the analysis of composite Ti/hydrocarbon plasma polymer thin films

    NASA Astrophysics Data System (ADS)

    Choukourov, A.; Grinevich, A.; Slavinska, D.; Biederman, H.; Saito, N.; Takai, O.

    2008-03-01

    Composite Ti/hydrocarbon plasma polymer films with different Ti concentration were deposited on silicon by dc magnetron sputtering of titanium in an atmosphere of argon and hexane. As measured by Kelvin force microscopy and visco-elastic atomic force microscopy, respectively, surface potential and hardness increase with increasing Ti content. Adhesion force to silicon and to fibrinogen molecules was stronger for the Ti-rich films as evaluated from the AFM force-distance curves. Fibrinogen forms a very soft layer on these composites with part of the protein molecules embedded in the outermost region of the plasma polymer. An increase of the surface charge due to fibrinogen adsorption has been observed and attributed to positively charged αC domains of fibrinogen molecule.

  20. 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.