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Thin Polymer Films (thin + polymer_film)
Selected AbstractsNanopatterning via Pressure-Induced Instabilities in Thin Polymer FilmsADVANCED MATERIALS, Issue 20 2009Ximin He The residual stresses in spin-coated films can be exploited to produce highly controlled nanoscale patterns via pressure-induced local rupturing and dewetting of thin films. Residue-free holes as small as 28,nm in diameter formed over large areas by pressing sharp stamps into polymer films at temperatures well below the glass transition temperature. [source] Two Coexisting Modes in Field-Assisted AFM Nanopatterning of Thin Polymer FilmsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2008Xian Ning Xie Abstract Two coexisting mechanisms, i.e., electrohydrodynamic destabilization and electrostatic detachment, for polymer nanostructuring in field-assisted atomic force microscope nanolithography are presented. The electrohydrodynamic destabilization mechanism is based on the surface instability of molten polymer film in the form of surface waves, and it leads to the formation of well defined polymeric wave patterns. The electrostatic detachment mechanism is associated with nano-blister formation caused by pre-existing defects, such as buried cavities in the polymer, and is responsible for the creation of hollow pillar-like structures. Here, the coexistence and pattern formation probability of the two polymer patterning modes under similar nanolithographic conditions are discussed. It was found that the field strength and the efficiency of probe-induced joule heating can significantly change the flow property of the polymer, which eventually leads to the occurrence of the two modes. The results presented here are useful in obtaining a complete picture of the diverse behaviors of polymers in AFM nanolithographic operations. [source] Plasma polymerization and deposition of glycidyl methacrylate on Si(100) surface for adhesion improvement with polyimidePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2001X. P. Zou Abstract Thin polymer films were deposited on Si(100) surfaces by plasma polymerization of glycidyl methacrylate (GMA) under different glow discharge conditions. The FT-IR, X-ray photoelectron spectroscopy (XPS), and amine treatment results suggested that the epoxide functional groups of the deposited films had been preserved to various extents, depending on the plasma deposition conditions. The use of a low radio frequency power (, 5 W) and a relatively high system pressure (100,400 Pa) readily resulted in the deposition of thin films having nearly the same composition of the epoxide functional groups as that of the GMA homopolymer. The plasma-polymerized GMA (PP-GMA) thin films deposited on the Ar plasma-pretreated Si(100) surfaces were retained to a large extent after acetone extraction, suggesting the presence of covalent bonding between the PP-GMA layer and the Si surface. Thermal imidization of the poly(amic acid) precursor of polyimide on the GMA plasma-polymerized Si(100) surface resulted in a strongly adhered polyimide film. The adhesion results further suggested that the GMA polymer had been grafted on the Si(100) surface and the epoxide functional groups had undergone reactive interaction (curing) with the carboxylic and amine groups of the poly(amic acid) during thermal imidization. Copyright © 2001 John Wiley & Sons, Ltd. [source] Polydivinylbenzene/Ethylvinylbenzene Composite Membranes for the Optimization of a Whole Blood Glucose SensorELECTROANALYSIS, Issue 1 2006Kerry Bridge Abstract A novel ultra thin polydivinylbenzene/ethylvinylbenzene composite membrane has been developed for use as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The composite membrane was formed via the cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of gold sputter coated host alumina membranes, (serving solely as a mechanical support for the thin polymer film). Permeability coefficients were determined for the enzyme substrates, O2 and glucose, across composite membranes formed with a range of polymer thicknesses. Due to the highly substrate diffusion limiting nature of the composite membrane, it was found that anionic interferents present in blood (such as ascorbate), were effectively screened from the working electrode via a charge exclusion mechanism, in a manner similar to previous findings within our laboratory. The enzyme electrode showed an initial 32% signal drift when first exposed to whole human blood over a period of 2 hours, after which time enzyme electrode responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r2=0.97 in comparison to standard hospital analyses. [source] Nanopatterning by an Integrated Process Combining Capillary Force Lithography and Microcontact PrintingADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Xuexin Duan Abstract A novel nanopatterning process was developed by combining capillary force lithography (CFL) and microcontact printing (µCP). Flat polydimethylsiloxane (PDMS) was used as the substrate in CFL, and after chemical functionalization, as the stamp in µCP, which increased the resolution of both methods. The polymer patterns, produced by CFL on a thin polymer film on the flat PDMS substrate, acted as a mask to oxidize the uncovered regions of the PDMS. The chemical patterns were subsequently formed by gas phase evaporation of a fluorinated silane. After removal of the polymer, these stamps were used to transfer thiol inks to a gold substrate by µCP. Gold patterns at a scale of less than 100,nm were successfully replicated by these chemically patterned flat PDMS stamps. [source] Modelling of thin polymer filmsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Michael Johlitz If we bond substrates like metal sheets by a thin polymer film we know about the existence of a boundary layer between the polymer and the substrate. The properties of this boundary layer differ from the bulk properties and influence the overall behavior of the bond. Here we present a mechanical theory based on a scalar-valued order parameter that allows us to describe these effects. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of deposition temperature on the properties of thin polymer films deposited by plasma-enhanced CVD using cyclo-hexa-hydrocarbons as monomersELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 4 2010Kazunori Moriki Abstract Plasma CVD is a candidate technology for the fabrication of optical polymer waveguides. It can deposit a film on any surface geometry and any substrate material at a temperature under 200 °C in a vacuum process. It also provides good thickness controllability and uniformity of the deposition film. In the present study, the effects of the deposition temperature on film properties, specifically the refractive index, deposition rate, and molecular structure, are discussed. The refractive index decreases as the deposition temperature rises. The logarithm of the deposition rate increases with the reciprocal of the temperature and the gradient of the deposition rate depends on the relative abundance of double bonds in the monomer source. The gradient does not change when CF4 is used instead of Ar as the gas mixed into the plasma, although the deposition rate increases by a factor of about five. We speculate that the deposition rate increases due to the increase in the abundance precursors produced by the presence of CF4 in the plasma and due to an increased abundance of dangling bonds on the surface of the deposition film caused by F radicals. We further speculate that the precursors incorporated into the polymer are selected on the substrate by the density of adsorption sites and the adsorption energy. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(4): 27,35, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10171 [source] Capillary Force Lithography: A Versatile Tool for Structured Biomaterials Interface Towards Cell and Tissue Engineering,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Kahp-Yang Suh Abstract This Feature Article aims to provide an in-depth overview of the recently developed molding technologies termed capillary force lithography (CFL) that can be used to control the cellular microenvironment towards cell and tissue engineering. Patterned polymer films provide a fertile ground for controlling various aspects of the cellular microenvironment such as cell,substrate and cell,cell interactions at the micro- and nanoscale. Patterning thin polymer films by molding typically involves several physical forces such as capillary, hydrostatic, and dispersion forces. If these forces are precisely controlled, the polymer films can be molded into the features of a polymeric mold with high pattern fidelity and physical integrity. The patterns can be made either with the substrate surface clearly exposed or unexposed depending on the pattern size and material properties used in the patterning. The former (exposed substrate) can be used to adhere proteins or cells on pre-defined locations of a substrate or within a microfluidic channel using an adhesion-repelling polymer such as poly(ethylene glycol) (PEG)-based polymer and hyaluronic acid (HA). Also, the patterns can be used to co-culture different cells types with molding-assisted layer-by-layer deposition. In comparison, the latter (unexposed substrate) can be used to control the biophysical surrounding of a cell with tailored mechanical properties of the material. The surface micropatterns can be used to engineer cellular and multi-cellular architecture, resulting in changes of the cell shape and the cytoskeletal structures. Also, the nanoscale patterns can be used to affect various aspects of the cellular behavior, such as adhesion, proliferation, migration, and differentiation. [source] Organic Thin Film Transistors with Polymer Brush Gate Dielectrics Synthesized by Atom Transfer Radical PolymerizationADVANCED FUNCTIONAL MATERIALS, Issue 1 2008C. Pinto Abstract Low operating voltage is an important requirement that must be met for industrial adoption of organic field-effect transistors (OFETs). We report here solution fabricated polymer brush gate insulators with good uniformity, low surface roughness and high capacitance. These ultra thin polymer films, synthesized by atom transfer radical polymerization (ATRP), were used to fabricate low voltage OFETs with both evaporated pentacene and solution deposited poly(3-hexylthiophene). The semiconductor-dielectric interfaces in these systems were studied with a variety of methods including scanning force microscopy, grazing incidence X-ray diffraction and neutron reflectometry. These studies highlighted key differences between the surfaces of brush and spun cast polymethyl methacrylate (PMMA) films. [source] Organic LEDs: The Simple Way to Solution-Processed Multilayer OLEDs , Layered Block-Copolymer Networks by Living Cationic Polymerization (Adv. Mater.ADVANCED MATERIALS, Issue 8 20098/2009) A novel strategy for simple, intelligent, and cost-effective fabrication of multilayer OLEDs by solution-processing is demonstrated by Klaus Meerholz and co-workers on p. 879. The cover shows the self-smoothing of thin polymer films using this method, termed "layer-by-layer crosslinking" (LBLX). LBLX enables the crosslinking and smoothing of several polymer layers on top of each other simply by using a heat and wash procedure. [source] Synthesis of polymeric 1-iminopyridinium ylides as photoreactive polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010Daniel Klinger Abstract Two synthetic routes to polymeric 1-imino pyridinium ylides as new photoreactive polymeric architectures were investigated. In the first approach, polymerization of newly synthesized 1-imino pyridinium ylide containing monomers yielding their polymeric analogues was achieved by free radical polymerization. Alternatively, reactive precursor polymers were synthesized and converted into the respective 1-imino pyridinium ylide polymers by polymer analogous reactions on reactive precursor polymers. Quantitative conversion of the reactive groups was achieved with pentafluorophenyl ester containing polymers and newly synthesized photoreactive amines as well as by the reaction of poly(4-vinylbenzoyl azide) with a photoreactive alcohol. The polymers obtained by both routes were examined regarding their photoreaction products and kinetics in solution as well as in thin polymer films. Contact angle measurements of water on the polymer films before and after irradiation showed dramatic changes in the hydrophilicity of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 832,844, 2010 [source] Response Characteristics of Thermoresponsive Polymers Using Nanomechanical Cantilever SensorsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2009Calvin Bradley Abstract We investigated coatings of thermally responsive thin polymer films prepared on nanomechanical cantilever sensor (NCS): (i) a PNIPAM brush, and (ii) an interlinked ppDEA polymer. Upon heating from 22 to 50,°C in water, a minimum in the differential deflection between 31.9,±,1.7,°C (PNIPAM) and 47.7,±,1.9,°C (ppDEA) was measured. The minimum in differential deflection can be associated with the lower critical solution temperature (LCST) of the films. Below the LCST the NCS deflection corresponds to a bending toward the thermally responsive polymer film side, associated to dehydration. At higher temperature, the deflection was reversed, i.e., away from the polymer coating. This response is mainly attributed to a bimaterial effect between the collapsed polymer and the NCS material. The LCST of the PNIPAM brush layer and the ppDEA film were close to that reported for the bulk polymers. [source] Anomalous current,voltage characteristics of thin polymer filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2003V. A. Kolesnikov Abstract In this paper we have investigated organic light emitting diodes with such electroluminescent materials as aromatic polyimide, poly,N-vinylcarbazole (PVK) and dye doped PVK. N-type current,voltage characteristics with negative differential resistance for the thin polymeric and organic films are analyzed. No reasonable explanation has been provided for this phenomenon until now. Here we suggest that a polymer(organic)/metal interface containing various inhomogeneities and metal spikes is responsible for this effect. We detect also the black-body radiation, whose temperature exceeds both the melting point and the sublimation temperature of the metal of the electrode. We suppose that the current density through the spike in any cases is large enough to cause the explosion of the tip of the spike and the detected radiation has the hot plasma origin. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modelling of thin polymer filmsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Michael Johlitz If we bond substrates like metal sheets by a thin polymer film we know about the existence of a boundary layer between the polymer and the substrate. The properties of this boundary layer differ from the bulk properties and influence the overall behavior of the bond. Here we present a mechanical theory based on a scalar-valued order parameter that allows us to describe these effects. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||