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Composite Films (composite + film)
Selected AbstractsA Novel Polycatechol/Ordered Mesoporous Carbon Composite Film Modified Electrode and Its Electrocatalytic ApplicationELECTROANALYSIS, Issue 15 2010Jing Bai Abstract Polycatechol (PCC) was prepared by electropolymerizing catechol (CC) on the surface of an ordered mesoporous carbon (OMC) modified electrode for the first time. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) were used to characterize the structure and electrochemical behaviors of PCC/OMC nanocomposite film. Compared with the bare GC and OMC/GC electrodes, the PCC/OMC/GC electrode exhibits a good electrocatalysis toward the oxidation of NADH at 0.0,V with a high sensitivity (8.7 mA/mM). These make PCC/OMC/GC electrode a promising candidate for stable and efficient electrochemical sensors for the detection of NADH. [source] Properties of Poly(sodium 4-styrenesulfonate)-Ionic Liquid Composite Film and Its Application in the Determination of Trace Metals Combined with Bismuth Film ElectrodeELECTROANALYSIS, Issue 5 2008Jianbo Jia Abstract A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4-styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)64,/Fe(CN)63, can be effectively improved at the PSS-BMIMPF6 modified GC. The bismuth modified PSS-BMIMPF6 composite film electrodes (GC/PSS-BMIMPF6/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS-BMIMPF6/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50,,g L,1. And the detection limits were 0.07,,g L,1 for Cd(II) and 0.09,,g L,1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120,s, respectively. Finally, the GC/PSS-BMIMPF6/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy. [source] Reversible Luminescent Switching in a [Eu(SiW10MoO39)2]13, -Agarose Composite Film by Photosensitive Intramolecular Energy TransferADVANCED MATERIALS, Issue 17 2009Zhongliang Wang Transparent, flexible, self-supporting EuSiWMo/agarose composite films are fabricated by a combination of hydrogel chemistry and a casting technique, and present reversible, high-contrast luminescence photoswitching modulated by inorganic photochromic components through intramolecular resonance-energy transfer. Two-dimensional recording employing the luminescence as read-out signals is accomplished in this novel recording medium. [source] Electrically Controllable Omnidirectional Laser Emission from a Helical-Polymer Network Composite FilmADVANCED MATERIALS, Issue 7 2009Byoungchoo Park A liquid-crystal/polymer composite is used to produce a photonic bandgap system. Films of the composite show a large field-induced reversible color shift of the reflection band of over 150 nm. Intensity-controllable laser emission at relatively low lasing thresholds is generated from composite films doped with dye. Moreover, the laser exhibits omnidirectional emission propagation on application of an electric field. [source] Preparation and Electrical Properties of an Anodized Al2O3,BaTiO3 Composite FilmJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Xianfeng Du A highly stable, water-based barium titanate BaTiO3, BT, sol was synthesized using a sol,gel route through a chelate lactate technique. Dried BT precursor powders were measured by thermal gravimetry,differential thermal analysis and X-ray diffraction. It was found that BT powders first converted into barium carbonate BaCO3, Ti complex, and intermediate phase Ba2Ti2O5CO3, and then transformed into perovskite phase BaTiO3. The crystallization temperature was about 550°C. The low-voltage etched aluminum foils were covered with BT sol by dip coating, and then annealed at 600°C for 30 min in air. After that, the samples were anodized in a 15 wt% aqueous solution of ammonium adipate. The voltage,time variations during anodizing were monitored, and the electrical properties of the anodic oxide film were examined. It was shown that the specific capacitance, the product of specific capacitance and withstanding voltage, and leakage current of samples with a BT coating were about 48.93%, 38.50%, and 167% larger than that without a BT coating, respectively. [source] Preparation of Nano-Structured Polyaniline Composite Film via "Carbon Nanotubes Seeding" Approach and its Gas-Response StudiesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2006Xingfa Ma Abstract Summary: Polyaniline composite film with nano-structure was prepared through a chemical oxidation method by adding carbon nanotubes (CNTs) as nano-fiber seeds. Spin-coating or casting method was employed on the interdigital electrodes of carbon and the composite film was formed with an in-situ polymerization approach. The gas-response to trimethylamine was also examined at room temperature. It was found that the difference was not only in the morphology, but also in the value of gas-sensitivity. Comparing with films without the CNTs, the value of gas-sensitivity decreased dramatically, while the baseline current of the sensor increased remarkably. This method can be an effective way to adjust the gas-sensitivity of sensors made from polyaniline composite film by adding a small amount of carbon nanotube. XRD data showed that the degree of orientation of polyaniline was increased greatly with the addition of CNTs. Morphology and reproducibility (inset) of polyaniline composite film containing carbon nanotubes. [source] Tris(2,2,-bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Platinized Carbon Nanotube,Zirconia,Nafion Composite FilmsELECTROANALYSIS, Issue 12 2010Hyun Yoon Abstract Mesoporous films of platinized carbon nanotube,zirconia,Nafion composite have been used for the immobilization of tris(2,2,-bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt,CNT,zirconia,Nafion exhibit much larger pore diameter (3.55,nm) than that of Nafion (2.82,nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia,Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt,CNT,zirconia,Nafion gave a linear response (R2=0.999) for TPA concentration from 3.0,nM to 1.0,mM with a remarkable detection limit (S/N=3) of 1.0,nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol-gel ceramic,Nafion composite films such as silica,Nafion and titania,Nafion. [source] Fabrication and Properties of Conducting Polypyrrole/SWNT-PABS Composite Films and NanotubesELECTROANALYSIS, Issue 11 2006Abstract We report the electropolymerization and characterization of polypyrrole films doped with poly(m-aminobenzene sulfonic acid (PABS) functionalized single-walled nanotubes (SWNT) (PPy/SWNT-PABS). The negatively charged water-soluble SWNT-PABS served as anionic dopant during the electropolymerization to synthesize PPy/SWNT-PABS composite films. The synthetic, morphological and electrical properties of PPy/SWNT-PABS films and chloride doped polypyrrole (PPy/Cl) films were compared. Characterization was performed by cyclic voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. SEM and AFM images revealed that the incorporation of SWNT-PABS significantly altered the morphology of the PPy. Cyclic voltammetry showed improved electrochemical properties of PPy/SWNT-PABS films as compared to PPy/Cl films. Raman Spectroscopy confirmed the presence of SWNT-PABS within composite films. Field effect transistor (FET) and electrical characterization studies show that the incorporation of the SWNT-PABS increased the electronic performance of PPy/SWNT-PABS films when compared to PPy/Cl films. Finally, we fabricated PPy/SWNT-PABS nanotubes which may lead to potential applications to sensors and other electronic devices. [source] One-Pot Preparation of Polymer,Enzyme,Metallic Nanoparticle Composite Films for High-Performance Biosensing of Glucose and GalactoseADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Yingchun Fu Abstract New polymer,enzyme,metallic nanoparticle composite films with a high-load and a high-activity of immobilized enzymes and obvious electrocatalysis/nano-enhancement effects for biosensing of glucose and galactose are designed and prepared by a one-pot chemical pre-synthesis/electropolymerization (CPSE) protocol. Dopamine (DA) as a reductant and a monomer, glucose oxidase (GOx) or galactose oxidase (GaOx) as the enzyme, and HAuCl4 or H2PtCl6 as an oxidant to trigger DA polymerization and the source of metallic nanoparticles, are mixed to yield polymeric bionanocomposites (PBNCs), which are then anchored on the electrode by electropolymerization of the remaining DA monomer. The prepared PBNC material has good biocompatibility, a highly uniform dispersion of the nanoparticles with a narrow size distribution, and high load/activity of the immobilized enzymes, as verified by transmission/scanning electron microscopy and electrochemical quartz crystal microbalance. The thus-prepared enzyme electrodes show a largely improved amperometric biosensing performance, e.g., a very high detection sensitivity (99 or 129,µA cm,2 mM,1 for glucose for Pt PBNCs on bare or platinized Au), a sub-micromolar limit of detection for glucose, and an excellent durability, in comparison with those based on conventional procedures. Also, the PBNC-based enzyme electrodes work well in the second-generation biosensing mode. The proposed one-pot CPSE protocol may be extended to the preparation of many other functionalized PBNCs for wide applications. [source] Intact Pattern Transfer of Conductive Exfoliated Graphite Nanoplatelet Composite Films to Polyelectrolyte Multilayer Platforms,ADVANCED MATERIALS, Issue 10 2008Troy R. Hendricks A simple method for creating patterned conductive multilayered polymer/exfoliated graphite nanoplatelet (xGnP) nanocomposite films is presented, by using the LBL assembly of xGnP and the intact pattern transfer of these films to a substrate. After four bilayers are deposited onto the stamp, conductive patterns can be created on virtually any substrate. [source] Nanomechanical Properties of Bioinspired Organic,Inorganic Composite Films,ADVANCED MATERIALS, Issue 7 2007Z. Burghard Nacre-like thin films are fabricated via a bioinspired route combining chemical bath deposition of the inorganic component (TiO2) and layer-by-layer alternate adsorption of oppositely charged polyelectrolytes for the organic component (see figure). Nanoindentation testing revealed an increase in hardness and Young's modulus imparted by the alternate-layer architecture of the composite films. [source] Functional Properties of Antimicrobial Lysozyme-Chitosan Composite FilmsJOURNAL OF FOOD SCIENCE, Issue 8 2004S.-I. Park ABSTRACT: Lysozyme-chitosan composite films were developed for enhancing the antimicrobial properties of chitosan films. A 10% lysozyme solution was incorporated into 2% chitosan film-forming solution (FFS) at a ratio of 0%, 20%, 60%, and 100% (w lysozyme/w chitosan). Films were prepared by solvent evaporation. Lysozyme release from the film matrix, the antimicrobial activity of films against Escherichia coli and Streptococcus faecalis, and basic film properties were investigated. The lysozyme release proportionally increased with increasing initial concentration of lysozyme in the film matrix, and the amount of released lysozyme was in natural log relationship with time. The films with 60% lysozyme incorporation enhanced the inhibition efficacy of chitosan films against both S. faecalis and E. coli, where 3.8 log cycles reduction in S. faecalis and 2.7 log cycles reduction in E. coli were achieved. Water vapor permeability of the chitosan films was not affected by lysozyme incorporation, whereas the tensile strength and percent elongation values decreased with increased lysozyme concentration. Scanning electron microscopy images revealed that lysozyme was homogeneously distributed throughout the film matrix. This study demonstrated that enhanced antimicrobial activity of lysozyme-chitosan composite films can be achieved by incorporating lysozyme into chitosan, thus broadening their applications in ensuring food quality and safety. [source] Fabrication of Patterned Polydiacetylene Composite Films Using a Replica-Molding (REM) TechniqueMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2010Oktay Yarimaga Abstract Functional three-dimensional (3D) micropatterns of diacetylene supramolecules embedded in a host polymer have been successfully fabricated by a replica-molding (REM) technique. Dimensional reduction as a result of liquid evaporation during the curing process does not affect the conformational features of the transferred patterns. Polymerization of the diacetylene vesicles using 254,nm UV-light irradiation from the back-side of the transparent substrate induces blue colored polydiacetylene (PDA) micro-images. Interestingly, the polymerization selectively occurs in the molded areas because of the sub-300,nm light blocking property of SU-8. 3D fluorescence patterns are readily obtained by heat treatment of the blue images on the film. [source] Advances in solid lubrication with MoS2 multilayered coatingsLUBRICATION SCIENCE, Issue 2 2001P. Voumard Abstract The general classification of solid lubricant types is reviewed, along with the reasons for choosing and methods of depositing solid lubricants, in particular MoS2. The best-performing and most flexible technique for making MoS2 films is by physical vapour deposition (PVD), and the variants of that technology are considered. The intrinsically-lubricating, lamellar structure of pure MoS2 is described, along with a brief summary of the wear and failure modes. Present applications for lubrication by MoS2 in spacecraft and dry machining are described. Anti-adhesion uses in extruding and moulding are also mentioned. The current modification of MoS2 films is by addition of dopants (co-sputtering), by multilayering as a series of films each fulfilling a specific task, or by stacking repeating nanometre-scale films. Composite films of MoS2 islands in a hard film matrix are also being developed. [source] Poly(3,4-ethylenedioxythiophene) (PEDOT)-Coated MWCNTs Tethered to Conducting Substrates: Facile Electrochemistry and Enhanced Coloring EfficiencyMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2008Shweta Bhandari Abstract Composite films of poly(3,4-ethylenedioxythiophene) (PEDOT)-coated over functionalized multiwalled coiled and linear carbon nanotubes (CNTs) have been fabricated by a simple oxidative electropolymerization route. The nanotubular morphology of the polymer,CNT composite is responsible for the lower charge transfer impedance, lower internal resistance, and superior capacitive response in comparison to that shown by the control PEDOT film doped by trifluoromethanesulfonate ions. This facile electrochemistry exhibited by the PEDOT,CNT composite film ensues in a remarkably high coloration efficiency of 367 cm2,·,C,1 at 550 nm, hitherto unrealized for PEDOT; thus demonstrating the huge potential the PEDOT,CNT composite film has as cathode for the entire spectrum of electrochromic devices. [source] Properties and interfacial bonding for regenerated cellulose,polyurethane/amylose acetate sipn composite filmsPOLYMER COMPOSITES, Issue 6 2000Jiahui Yu Composite films were obtained by placing a polyurethane/amylose acetate semi-interpenetrating polymer network (SIPN) coating onto the surfaces of regenerated cellulose (RC) film. The properties of the composite film, such as tensile strength, 79.9 MPa (in dry state), 49.5 MPa (in wet state), water resistance (R), 0.62, dimensional stability (Sc), 3.0%, and water vapor permeability (P), 5.96 × 10,5 Kgm,2h,1, are better than those of the uncoated RC film or RC film with PU coating. The interfacial strength was characterized with infrared spectroscopy (IR), ultraviolet spectroscopy (UV), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA). The results showed the existence of covalent and hydrogen bonds between the SIPN coat layer and the RC layer. It was also found that the PU prepolymer in the coating layer penetrated into the cellulose bulk, and reacted with the cellulose molecules, which formed another SIPN. [source] Composite Platinum/Silicon Dioxide Films Deposited using CVDCHEMICAL VAPOR DEPOSITION, Issue 3 2005P. Martin Abstract We report the low temperature deposition of platinum/silicon dioxide composite films from tetraethylorthosilicate (TEOS) and platinum acetylacetonate (Pt(acac)2). The simultaneous CVD of TEOS and Pt(acac)2, in the presence of oxygen, has been shown to reduce the decomposition temperature of TEOS to as low as 320,°C (from 600,°C without Pt(acac)2). Composite films were grown at temperatures ranging from 300,°C to 440,°C, using an estimated 5:1 flow rate of TEOS to Pt(acac)2 and in 0,70% oxygen atmosphere. The overall growth rate was maximized at 400,°C and the overall activation energy of the thin film formation was ,80 kJ mol,1. The SiO2 phase was amorphous and the platinum phase crystalline with an average grain size of 9 nm as determined by X-ray diffraction (XRD). An in-situ Fourier-transform infrared (FTIR) spectroscopy study of the gas phase was undertaken to provide confirmation of the low temperature decomposition of TEOS promoted by Pt(acac)2. Despite the high Si/Pt ratio in the feed, the maximum observed Si/Pt ratio in the film was 1:1, suggesting a cooperative TEOS-Pt(acac)2 decomposition mechanism. [source] Direct Electrochemistry and Electrocatalysis of Hemoglobin in Lipid Film Incorporated with Room-Temperature Ionic LiquidELECTROANALYSIS, Issue 20 2008Gaiping Li Abstract A facile phospholipid/room-temperature ionic liquid (RTIL) composite material based on dimyristoylphosphatidylcholine (DMPC) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) was exploited as a new matrix for immobilizing protein. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were adopted to characterize this composite film. Hemoglobin (Hb) was chosen as a model protein to investigate the composite system. UV-vis absorbance spectra showed that Hb still maintained its heme crevice integrity in this composite film. By virtue of the Hb/DMPC/[bmim]PF6 composite film-modified glassy carbon electrode (GCE), a pair of well-defined redox peaks of Hb was obtained through the direct electron transfer between protein and underlying GCE. Moreover, the reduction of O2 and H2O2 at the Hb/DMPC/[bmim]PF6 composite film-modified GCE was dramatically enhanced. [source] Direct Electron Transfer and Electrocatalysis of Hemoglobin on Chitosan-TiO2 Nanorods-Glass Carbon ElectrodeELECTROANALYSIS, Issue 20 2008Xiaoling Xiao Abstract The direct electron transfer between hemoglobin (Hb) and the glassy carbon electrode (GC) can be readily achieved via a high biocompatible composite system based on biopolymer chitosan (CHT) and TiO2 nanorods (TiO2 -NRs). TiO2 -NRs greatly promote the electron transfer between Hb and GC, which contribute to the higher redox peaks. UV-vis spectra result indicated the Hb entrapped in the composite film well keep its native structure. The immobilized Hb remains its bioelectrocatalytical activity to the reduction of H2O2 with a lower detection limit. A novel, sensitive, reproducible and stable electrochemical biosensing platform of H2O2 based on Hb-TiO2 -CHT electrode is explored. [source] Direct Electrochemistry and Electrocatalysis of Myoglobin Immobilized on Gold Nanoparticles/Carbon Nanotubes Nanohybrid FilmELECTROANALYSIS, Issue 17 2008Wei Cao Abstract A novel nanohybrid material, constructed by gold nanoparticles (GNPs) and multiwalled carbon nanotubes (MWNTs), was designed for immobilization and biosensing of myoglobin (Mb). Morphology of the nanohybrid film was characterized by SEM. UV-vis spectroscopy demonstrated that Mb on the composite film could retain its native structure. Direct electrochemistry of Mb immobilized on the GNPs/MWNTs film was investigated. The immobilized Mb showed a couple of quasireversible and well-defined cyclic voltammetry peaks with a formal potential of about ,0.35,V (vs. Ag/AgCl) in pH,6.0 phosphate buffer solution (PBS) solution. Furthermore, the modified electrode also displayed good sensitivity, wide linear range and long-term stability to the detection of hydrogen peroxide. The experiment results demonstrated that the hybrid matrix provided a biocompatible microenvironment for protein and supplied a necessary pathway for its direct electron transfer. [source] Synthesis and Characterization of MWNTs/Au NPs/HS(CH2)6Fc Nanocomposite: Application to Electrochemical Determination of Ascorbic AcidELECTROANALYSIS, Issue 16 2008Jian-Ding Qiu Abstract In this article, a detailed electrochemical study of a novel 6-ferrocenylhexanethiol (HS(CH2)6Fc) self-assembled multiwalled carbon nanotubes-Au nanoparticles (MWNTs/Au NPs) composite film was demonstrated. MWNTs/Au NPs were prepared by one-step in situ synthesis using linear polyethyleneimine (PEI) as bifunctionalizing agent. HS(CH2)6Fc, which acted as the redox mediator, was self-assembled to MWNTs/Au NPs via Au-S bond. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier transformed infrared absorption spectroscopy (FT-IR), UV-visible absorption spectroscopy, and cyclic voltammetry were used to characterize the properties of the MWNTs/Au NPs/HS(CH2)6Fc nanocomposite. The preparation of the nanocomposite was very simple and effectively prevented the leakage of the HS(CH2)6Fc mediator during measurements. The electrooxidation of AA could be catalyzed by Fc/Fc+ couple as a mediator and had a higher electrochemical response due to the unique performance of MWNTs/Au NPs. The nanocomposite modified electrode exhibited excellent catalytic efficiency, high sensitivity, good stability, fast response (within 3,s) and low detection limit toward the oxidation of AA at a lower potential. [source] Tuning and Transcription of the Supramolecular Organization of a Fluorescent Silsesquioxane Precursor into Silica-Based Materials through Direct Photochemical Hydrolysis,Polycondensation and MicropatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Xavier Sallenave Abstract A new fluorescent silsequioxane precursor with tuned optical properties and controlled aggregation properties is designed. The two cyclohexyl moieties introduced in the molecular structure allow the formation of very good quality films. The J-aggregated structure is transcribed into the solid by photoacid-catalyzed hydrolysis,polycondensation. Aggregation of the chromophores is reduced and highly fluorescent materials are obtained. The photoacid generator lies on the surface of the homogeneous layer of the sol,gel precursor. This phase separation presents several advantages, including UV protection of the chromophore and easy removal of the PAG. The first example of chemical amplification in the photolithography of the conjugated silsesquioxane precursor is demonstrated. As hydrolysis,polycondensation could be achieved in a controlled way by UV exposure, chemically amplified photolithography is achieved by irradiating a composite film (,110,nm thick) on silicon wafer by using a copper TEM grid as shadow mask. The pattern is produced uniformly on a miscroscopic scale of 3,mm, the photopatterned pixels remaining highly fluorescent. The sizes of the photolithographed pixels correspond to the sizes of the rectangular holes of the 300,×,75 mesh grid (hole: 63,<$>,<$>m,×,204,<$>,<$>m). [source] Preparation and characterization of PDLC films formed using a two-step procedureADVANCES IN POLYMER TECHNOLOGY, Issue 1 2007Yu-Che Hsiao Abstract A novel polymer-dispersed liquid crystal composite film was prepared using liquid crystal and dual resins, namely, UV-curable urethane diacrylate and thermo-curable epoxy, with a fixed LC content of 50 wt%. A combination treatment of UV irradiation and heat was performed in sequential steps. At first, the urethane diacrylate resin was cross-linked through UV irradiation and a pre-UV-cured film was formed. Then, the pre-UV-cured film was heat treated for curing the thermo-curable epoxy resin. As the thermal polymerization continued, LC droplets were formed and became embedded within the polymer matrix. PDLC films obtained from the polymer matrix with refractive indices in a range from 1.511 to 1.523 (1.517 ± 0.006) have optimal electro-optical properties. Films with a refractive index higher than 1.523 have high contrast ratio (CR), threshold voltage (Vth), and V90, whereas those with a low refractive index of 1.508 have low CR, Vth, and V90. In this study, we found that PDLC composite films with optimal compositions prepared by dual resins (UV/thermal) have good electro-optical properties. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:14,20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20087 [source] Enhanced photodegradation efficiency of polyethylene-TiO2 nanocomposite film with oxidized polyethylene waxJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Wenjun Fa Abstract A novel photodegradable polyethylene-oxidized polyethylene wax-TiO2 (PE-OPW-TiO2) nanocomposite film was prepared by embedding the organically modified TiO2 nanoparticles into commercial PE in the presence of OPW. The photocatalytic degradation behavior under ultraviolet light or solar light was investigated by examining the weight loss of the composite films, UV,vis transmittance spectrum, scanning electron microscope (SEM), and gel permeation chromatogram (GPC). The results show that OPW, as a dispersant and a compatibiliser, markedly improves the dispersion and compatibility of TiO2 nanoparticles in PE resins. The PE-OPW-TiO2 composite film demonstrates much higher photodegradation efficiency and much better mechanical property than either the PE-TiO2 composite film or the pure PE film. The weight-average molecular weight (Mw) of the PE-OPW-TiO2 composite film decreased 94.3% and the number-average molecular weight (Mn) decreased 84.5% after 38 days solar light irradiation. The photocatalytic degradation mechanism of the film is briefly discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Bioactive and mechanically strong Bioglass®-poly(D,L -lactic acid) composite coatings on surgical suturesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Q. Z. Chen Abstract New coating processes have been investigated for degradable (Vicryl®) and nondegradable (Mersilk®) sutures with the aim to develop Bioglass® coated polymer fibers for wound healing and tissue engineering scaffold applications. First, the aqueous phase of a Bioglass® particle slurry was replaced with a poly(D,L -lactic acid) (PDLLA) polymer dissolved in solvent dimethyle carbonate (DMC) to act as third phase. SEM observations indicated that this alteration significantly improved the homogeneity of the coatings. Second, a new coating strategy involving two steps was developed: the sutures were first coated with a Bioglass®,PDLLA composite film followed by a second PDLLA coating. This two-step process of coating has addressed the problem of poor adherence of Bioglass® particles on suture surfaces. The coated sutures were knotted to determine qualitatively the mechanical integrity of the coatings. The results indicated that adhesion strength of coatings obtained by the two-step method was remarkably enhanced. A comparative assessment of the bioactivity of one-step and two-step produced coatings was carried out in vitro using acellular simulated body fluid (SBF) for up to 28 days. Coatings produced by the two-step process were found to have similar bioactivity as the one-step produced coatings. The novel Bioglass®/PDLLA/Vicryl® and Bioglass®/PDLLA/Mersilk® composite sutures are promising bioactive materials for wound healing and tissue engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Ring-opening graft copolymerization of epoxide with polyaniline: Chemical properties and lithium ionic conductivity of the copolymerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2001Isao Yamaguchi The NaH-promoted deprotonation of leucoemeraldine base polyaniline (LEB) and its subsequent treatment with phenyl glycidyl ether (PGE) caused the ring-opening polymerization of PGE to give a graft copolymer (LEB- g -PGE). LEB- g -PGE was soluble in acetone and chloroform, which were poor solvents for LEB. An LEB- g -PGE/LiBF4 composite film was obtained through the evaporation of a dimethylformamide solution containing LEB- g -PGE and LiBF4; the film showed an electroconductivity of 1.0 × 10,6 S cm,1 at 295 K, as determined by complex impedance analysis. [source] Preparation of Nano-Structured Polyaniline Composite Film via "Carbon Nanotubes Seeding" Approach and its Gas-Response StudiesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2006Xingfa Ma Abstract Summary: Polyaniline composite film with nano-structure was prepared through a chemical oxidation method by adding carbon nanotubes (CNTs) as nano-fiber seeds. Spin-coating or casting method was employed on the interdigital electrodes of carbon and the composite film was formed with an in-situ polymerization approach. The gas-response to trimethylamine was also examined at room temperature. It was found that the difference was not only in the morphology, but also in the value of gas-sensitivity. Comparing with films without the CNTs, the value of gas-sensitivity decreased dramatically, while the baseline current of the sensor increased remarkably. This method can be an effective way to adjust the gas-sensitivity of sensors made from polyaniline composite film by adding a small amount of carbon nanotube. XRD data showed that the degree of orientation of polyaniline was increased greatly with the addition of CNTs. Morphology and reproducibility (inset) of polyaniline composite film containing carbon nanotubes. [source] Poly(3,4-ethylenedioxythiophene) (PEDOT)-Coated MWCNTs Tethered to Conducting Substrates: Facile Electrochemistry and Enhanced Coloring EfficiencyMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2008Shweta Bhandari Abstract Composite films of poly(3,4-ethylenedioxythiophene) (PEDOT)-coated over functionalized multiwalled coiled and linear carbon nanotubes (CNTs) have been fabricated by a simple oxidative electropolymerization route. The nanotubular morphology of the polymer,CNT composite is responsible for the lower charge transfer impedance, lower internal resistance, and superior capacitive response in comparison to that shown by the control PEDOT film doped by trifluoromethanesulfonate ions. This facile electrochemistry exhibited by the PEDOT,CNT composite film ensues in a remarkably high coloration efficiency of 367 cm2,·,C,1 at 550 nm, hitherto unrealized for PEDOT; thus demonstrating the huge potential the PEDOT,CNT composite film has as cathode for the entire spectrum of electrochromic devices. [source] Preparation and conversion electron Mössbauer study of Fe3O4/,-Fe2O3 composite filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2006Z. P. Niu Abstract Fe3O4 and Fe3O4/,-Fe2O3 composite films have been prepared from a sintered Fe2O3 target, using an rf magnetron sputtering apparatus with various argon pressures. The phase and magnetic properties of the samples have been characterized by X-ray-diffraction (XRD) measurements, conversion electron Mössbauer spectroscopy (CEMS), and a vibrating sample magnetometer (VSM). With the increasing argon pressure during sputtering, the increase of the average center shift of Mössbauer lines indicates the decreasing valency state of Fe ions induced by the enhancement of presumed oxygen loss. An enhanced magnetoresistance (MR) has been found in the Fe3O4/,-Fe2O3 composite film that was prepared under an Ar pressure of 1.0 Pa. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanoporous oxides of refractory metals: fabrication and propertiesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008S. K. Lazarouk Abstract A new approach to fabrication of nanoporous oxides of refractory metals is presented. It is based on the magnetron co-sputtering of aluminum and refractory metal (titanium, niobium or tungsten) followed by porous electrochemical anodization of the composite film and selective etching of alumina. The nanoporous oxide films with a thickness up to 5 µm were fabricated and studied. The porosity of the oxide films characterized by the surface area of 230 , 460 m2/cm3 can betuned by the aluminum content in the as-deposited composite films. The pore diameters are found to be varied in nanometer and subnanometer ranges. The parameters of porous titania within porous alumina matrix for different titanium concentrations are presented. The fabricated porous composite oxide films are characterized by the refractive index in the range from 1.45 to 1.77. The dielectric permeability for these films is found to be varied from 6.7 to 24. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||||||||