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Showing papers on "Polymer published in 2003"


Journal ArticleDOI
TL;DR: A review of the academic and industrial aspects of the preparation, characterization, materials properties, crystallization behavior, melt rheology, and processing of polymer/layered silicate nanocomposites is given in this article.

6,343 citations


Book
01 Jan 2003
TL;DR: In this article, the authors present a survey of the properties of polymers and their application in the field of chemical engineering, including the following: Coextrusion, Injection Molding, Flexible Packaging, Fibers, Polymer-Clay, and Plasticizers.
Abstract: VOLUME 1. Acetylenic Polymers, Substituted. Acrylamide Polymers. Acrylic (and Methacrylic) Acid Polymers. Acrylic Ester Polymers. Acrylonitrile and Acrylonitrile Polymers. Acrylonitrile-Butadiene-Styrene Polymers. Additives. Adhesion. Adhesive Compounds. Aging, Physical. Alkyd Resins. Am,ino Resins and Plastics. Antifoaming Agents. Atomic Force Microscopy. Biotechnology Applications. Bloack Copolymers. Bloack Copolymers, Ternary Triblock. Blow Molding. Chitin and Chitosan. Chromatography, Affinity. Chromatography, HPLC. Chromatography, Size Exclusion. Coating Methods, Survey. Coatings. VOLUME 2 Coextrusion. Colorants. Coloring Processes. Composites, Fabrication. Conformation and Configuration. Critical Phase Polymerizations. Cyclohexanedimethanol Polyesters. Dendronized Polymers. Dental Applications. Diacethylene and Triacethylene Polymers. Elasticity, Rubber-Like. Electronic Packaging. Electrooptical Applications. Engineering, Thermoplastics, Overview. Enzymatic Polymerization. Ethylene Polymers, Chlorosulfonated. Ethylene Polymers, HDPE. Ethylene Polymers, LDPE. Ehtylene Polymers, LLDPE. Ethylene-Acrylic Elastomers. Ethylene-Norbornene Copolymers. Extrusion. Films, Orientation. Fluorocarbon Elastomers. Fractography. Fracture. Glass Transition. Hardness. Hydrogels. Hyperbranched Polymers. VOLUME 3 Injection Molding. Inorganic Polymers. Laser Light Scattering. Light-Emiting Diodes. Lignin. Liquid Crystalline Polymers, Main-Chain. Liquid Crystalline Thermosets. Mass Spectrometry. Membrane Technology. Methacrylic Ester Polymers. Micromechanical Properties. Modeling of Polymer Processing and Properties. Nanocomposites, Polymer-Clay. Packaging, Flexible. Perfluorinated Polymers, Perfluorinated Ethylene-Propylene Copolymers. Perfluorinated Polymers Polytetrafluoroethylene. Perfluorinated Polymers Tetrafluoroethylene-Ethylene Copolymers. Perfluorinated Polymers, Tetrafluoroethylene-Perfluorinated Copolymers. Perfluorinated Polymers. Tetrafluoroethylene-Perfluorovinyl Ether Copolymers. Phosgene. Phosphorus-Containing Polymers and Oligomers. Piezoelectric Polymers. Plasticizers. Poly(3-Hydroxyalkanoates). Poly(Trimethylene Terephthalate). Polyamides, Atomatic. Polyamides, Fibers. Polyamides, Plastics. Polycyanoacrylates. Polyesters, Fibers. Polyketones. Polynucleotides. Polysulfides. VOLUME 4 Polysulfones. Polyurethanes. Pressure-Sensitive Adhesive. Reinforcement. Release Agents. Shape-Memory Polymers. Single-Site Catalysis. Stabilization. Styrene-Butadiene Rubber (SBR). Styrene Polymers. Sulfur-Containing Polymers. Surface Properties. Syndiotactic Polystyrene. Vinyl Fluoride Polymers (PVF). Vinylidene Chloride Polymers. Vinylidene Fluoride Polymers. Viscoelasticity. Weathering.

3,190 citations


Journal ArticleDOI
TL;DR: In this article, individual single-walled carbon nanotubes (SWNTs) have been suspended in aqueous media using various anionic, cationic, nonionic surfactants and polymers.
Abstract: Individual single-walled carbon nanotubes (SWNTs) have been suspended in aqueous media using various anionic, cationic, nonionic surfactants and polymers. The surfactants are compared with respect to their ability to suspend individual SWNTs and the quality of the absorption and fluorescence spectra. For the ionic surfactants, sodium dodecylbenzene sulfonate (SDBS) gives the most well resolved spectral features. For the nonionic systems, surfactants with higher molecular weight suspend more SWNT material and have more pronounced spectral features.

1,682 citations


Journal ArticleDOI
27 Jun 2003-Science
TL;DR: The use of a polymerizable ionic liquid as the gelling medium allows for the fabrication of a highly electroconductive polymer/nanotube composite material, which showed a substantial enhancement in dynamic hardness.
Abstract: When mixed with imidazolium ion-based room-temperature ionic liquid, pristine single-walled carbon nanotubes formed gels after being ground. The heavily entangled nanotube bundles were found to untangle within the gel to form much finer bundles. Phase transition and rheological properties suggest that the gels are formed by physical cross-linking of the nanotube bundles, mediated by local molecular ordering of the ionic liquids rather than by entanglement of the nanotubes. The gels were thermally stable and did not shrivel, even under reduced pressure resulting from the nonvolatility of the ionic liquids, but they would readily undergo a gel-to-solid transition on absorbent materials. The use of a polymerizable ionic liquid as the gelling medium allows for the fabrication of a highly electroconductive polymer/nanotube composite material, which showed a substantial enhancement in dynamic hardness.

1,258 citations


Journal ArticleDOI
TL;DR: The aim here is to discuss the usability of conducting polymers in both types of electronic applications in light of these two parameters: conductivity and work function.
Abstract: Conducting organic polymers have found two main kinds of application in electronics so far: as materials for construction of various devices and as selective layers in chemical sensors. In either case, interaction with ambient gases is critical. It may compromise the performance of a device based on conducting polymers, whereas it is beneficial in a sensor. Conductivity has been the primary property of interest. Work function--related to conductivity, but in principle a different property--has received only scant attention. Our aim here is to discuss the usability of conducting polymers in both types of electronic applications in light of these two parameters.

1,234 citations


Journal ArticleDOI
TL;DR: The quartz crystal microbalance technique is a simple, cost effective, high-resolution mass sensing technique, based upon the piezoelectric effect, which has witnessed an explosive growth in the application of the QCM technique to the study of a wide range of molecular systems at the solution-surface interface, in particular, biopolymer and biochemical systems.

1,077 citations


Journal ArticleDOI
20 Feb 2003-Nature
TL;DR: A class of electroluminescent polymers can be patterned in a way similar to standard photoresist materials—soluble polymers with oxetane sidegroups that can be crosslinked photochemically to produce insoluble polymer networks in desired areas.
Abstract: Organic light-emitting diodes (OLEDs) show promise for applications as high-quality self-emissive displays for portable devices such as cellular phones and personal organizers. Although monochrome operation is sufficient for some applications, the extension to multi-colour devices--such as RGB (red, green, blue) matrix displays--could greatly enhance their technological impact. Multi-colour OLEDs have been successfully fabricated by vacuum deposition of small electroluminescent molecules, but solution processing of larger molecules (electroluminescent polymers) would result in a cheaper and simpler manufacturing process. However, it has proved difficult to combine the solution processing approach with the high-resolution patterning techniques required to produce a pixelated display. Recent attempts have focused on the modification of standard printing techniques, such as screen printing and ink jetting, but those still have technical drawbacks. Here we report a class of electroluminescent polymers that can be patterned in a way similar to standard photoresist materials--soluble polymers with oxetane sidegroups that can be crosslinked photochemically to produce insoluble polymer networks in desired areas. The resolution of the process is sufficient to fabricate pixelated matrix displays. Consecutive deposition of polymers that are luminescent in each of the three RGB colours yielded a device with efficiencies comparable to state-of-the-art OLEDs and even slightly reduced onset voltages.

1,054 citations


Book
01 Jan 2003
TL;DR: In this paper, the authors present a review of the application of Nanocomposites in the following areas: 1.1 Encapsulated Composite Nanosystems, 2.2 Polyamide Matrices, 3.3 Polypropylene and Polyethylene Matrices and 4.4 Other Nanotubes.
Abstract: 1. Bulk Metal and Ceramics Nanocomposites (Pulickel M. Ajayan).1.1 Introduction.1.2 Ceramic/Metal Nanocomposites.1.2.1 Nanocomposites by Mechanical Alloying.1.2.2 Nanocomposites from SolGel Synthesis.1.2.3 Nanocomposites by Thermal Spray Synthesis.1.3 Metal Matrix Nanocomposites.1.4 Bulk Ceramic Nanocomposites for Desired Mechanical Properties.1.5 Thin-Film Nanocomposites: Multilayer and Granular Films.1.6 Nanocomposites for Hard Coatings.1.7 Carbon Nanotube-Based Nanocomposites.1.8 Functional Low-Dimensional Nanocomposites.1.8.1 Encapsulated Composite Nanosystems.1.8.2 Applications of Nanocomposite Wires.1.8.3 Applications of Nanocomposite Particles.1.9 Inorganic Nanocomposites for Optical Applications.1.10 Inorganic Nanocomposites for Electrical Applications.1.11 Nanoporous Structures and Membranes: Other Nanocomposites.1.12 Nanocomposites for Magnetic Applications.1.12.1 Particle-Dispersed Magnetic Nanocomposites.1.12.2 Magnetic Multilayer Nanocomposites.1.12.2.1 Microstructure and Thermal Stability of Layered Magnetic Nanocomposites.1.12.2.2 Media Materials.1.13 Nanocomposite Structures having Miscellaneous Properties.1.14 Concluding Remarks on Metal/Ceramic Nanocomposites.2. Polymer-based and Polymer-filled Nanocomposites (Linda S. Schadler).2.1 Introduction.2.2 Nanoscale Fillers.2.2.1 Nanofiber or Nanotube Fillers.2.2.1.1 Carbon Nanotubes.2.2.1.2 Nanotube Processing.2.2.1.3 Purity.2.2.1.4 Other Nanotubes.2.2.2 Plate-like Nanofillers.2.2.3 Equi-axed Nanoparticle Fillers.2.3 Inorganic FillerPolymer Interfaces.2.4 Processing of Polymer Nanocomposites.2.4.1 Nanotube/Polymer Composites.2.4.2 Layered FillerPolymer Composite Processing.2.4.2.1 Polyamide Matrices.2.4.2.2 Polyimide Matrices.2.4.2.3 Polypropylene and Polyethylene Matrices.2.4.2.4 Liquid-Crystal Matrices.2.4.2.5 Polymethylmethacrylate/Polystyrene Matrices.2.4.2.6 Epoxy and Polyurethane Matrices.2.4.2.7 Polyelectrolyte Matrices.2.4.2.8 Rubber Matrices.2.4.2.9 Others.2.4.3 Nanoparticle/Polymer Composite Processing.2.4.3.1 Direct Mixing.2.4.3.2 Solution Mixing.2.4.3.3 In-Situ Polymerization.2.4.3.4 In-Situ Particle Processing Ceramic/Polymer Composites.2.4.3.5 In-Situ Particle Processing Metal/Polymer Nanocomposites.2.4.4 Modification of Interfaces.2.4.4.1 Modification of Nanotubes.2.4.4.2 Modification of Equi-axed Nanoparticles.2.4.4.3 Small-Molecule Attachment.2.4.4.4 Polymer Coatings.2.4.4.5 Inorganic Coatings.2.5 Properties of Composites.2.5.1 Mechanical Properties.2.5.1.1 Modulus and the Load-Carrying Capability of Nanofillers.2.5.1.2 Failure Stress and Strain Toughness.2.5.1.3 Glass Transition and Relaxation Behavior.2.5.1.4 Abrasion and Wear Resistance.2.5.2 Permeability.2.5.3 Dimensional Stability.2.5.4 Thermal Stability and Flammability.2.5.5 Electrical and Optical Properties.2.5.5.1 Resistivity, Permittivity, and Breakdown Strength.2.5.5.2 Optical Clarity.2.5.5.3 Refractive Index Control.2.5.5.4 Light-Emitting Devices.2.5.5.5 Other Optical Activity.2.6 Summary.3. Natural Nanobiocomposites, Biomimetic Nanocomposites, and Biologically Inspired Nanocomposites (Paul V. Braun).3.1 Introduction.3.2 Natural Nanocomposite Materials.3.2.1 Biologically Synthesized Nanoparticles.3.2.2 Biologically Synthesized Nanostructures.3.3 Biologically Derived Synthetic Nanocomposites.3.3.1 Protein-Based Nanostructure Formation.3.3.2 DNA-Templated Nanostructure Formation.3.3.3 Protein Assembly.3.4 Biologically Inspired Nanocomposites.3.4.1 Lyotropic Liquid-Crystal Templating.3.4.2 Liquid-Crystal Templating of Thin Films.3.4.3 Block-Copolymer Templating.3.4.4 Colloidal Templating.3.5 Summary.4. Modeling of Nanocomposites (Catalin Picu and Pawel Keblinski).4.1 Introduction The Need For Modeling.4.2 Current Conceptual Frameworks.4.3 Multiscale Modeling.4.4 Multiphysics Aspects.4.5 Validation.Index.

910 citations


Journal ArticleDOI
TL;DR: Evidence that interchain electronic species do form in conjugated polymer films is reviewed and their number and chemical nature depend on processing conditions; the chain conformation, degree of interchain contact, and rate of energy transfer can be controlled by factors such as choice of solvent, polymer concentration, thermal annealing, presence of electrically charged side groups, and encapsulation of the polymer chains in mesoporous silica.
Abstract: The electronic structure of conjugated polymers is of current interest because of the wide range of potential applications for such materials in optoelectronic devices. It is increasingly clear that the electronic properties of conjugated polymers depend sensitively on the physical conformation of the polymer chains and the way the chains pack together in films. This article reviews the evidence that interchain electronic species do form in conjugated polymer films, and that their number and chemical nature depend on processing conditions; the chain conformation, degree of interchain contact, and rate of energy transfer can be controlled by factors such as choice of solvent, polymer concentration, thermal annealing, presence of electrically charged side groups, and encapsulation of the polymer chains in mesoporous silica. Taken together, the results reconcile many contradictions in the literature and provide a prescription for the optimization of conjugated polymer film morphology for device applications.

899 citations


Journal ArticleDOI
TL;DR: In this paper, a general overview of several aspects of the dissolution of amorphous polymers is provided, including experimentally observed dissolution phenomena and mechanisms reported to this date, solubility behavior of polymers and their solvents, models used to interpret and understand polymer dissolution, and techniques used to characterize the dissolution process.

885 citations


Journal ArticleDOI
01 Jun 2003-Polymer
TL;DR: In this paper, the authors investigated the crystallization behavior of nylon 6 nanocomposites formed by melt processing by extruding mixtures of organically modified montmorillonite and molten nylon 6 using a twin screw extruder.

Journal ArticleDOI
TL;DR: In this paper, the effect of fiber loading, frequency and temperature on the dynamic mechanical properties of a composite was analyzed with the consideration of the intrinsic properties of the components, morphology of the system and the nature of interface between the phases.

Journal ArticleDOI
TL;DR: In this article, the authors provide an overview of progress made in the development of proton-conducting hydrocarbon and heterocyclic-based polymers for direct methanol fuel cells and describe the various approaches made to polymer modification/synthesis and salient properties of the materials formed.
Abstract: ▪ Abstract The past 10 years have witnessed a tremendous acceleration in research devoted to non-fluorinated polymer membranes, both as competitive alternatives to commercial perfluorosulfonic acid membranes operating in the same temperature range and with the objective of extending the range of operation of polymer fuel cells toward those more generally occupied by phosphoric acid fuel cells. Important requirements are adequate membrane mechanical strength at levels of functionalization (generally sulfonation) and hydration allowing high proton conductivity, and stability in the aggressive environment of a working fuel cell, in particular thermohydrolytic and chemical stability. This review provides an overview of progress made in the development of proton-conducting hydrocarbon and heterocyclic-based polymers for proton exchange and direct methanol fuel cells and describes the various approaches made to polymer modification/synthesis and salient properties of the materials formed, including those relati...

Journal ArticleDOI
TL;DR: In this paper, the alternating copolymer with a C-60 derivative (PCBM) was used for solar cells with a power conversion efficiency of 2.2 % under simulated solar light.
Abstract: Solar cells prepared using the alternating copolymer shown in the Figure blended with a C-60 derivative (PCBM) are demonstrated to have a high performance, with a power conversion efficiency of 2.2 % under simulated solar light. The molecular weight of the polymer is low due to limited solubility, and films of the polymer exhibit red-shifted absorption.

Journal ArticleDOI
J. Lange1, Yves Wyser1
TL;DR: A comprehensive review of the different approaches, outlining the principle behind each barrier technology, its performance, its potential and the companies developing and producing the materials, can be found in this paper.
Abstract: The barrier solutions presently available on the market all have their drawbacks, e.g. cost, water-sensitivity, opacity or perceived environmental bad-will. At the same time there is a trend to use more plastic-based packaging materials for different applications, e.g. as replacements for metal and glass containers. This situation has stimulated the industry to provide new, more efficient barrier solutions. The innovations go along five major lines: (a) thin, transparent vacuum-deposited coatings; (b) new barrier polymers as discrete layers; (c) blends of barrier polymers and standard polymers; (d) organic barrier coatings; and (e) nanocomposite materials. This paper provides a comprehensive review of the different approaches, outlining the principle behind each barrier technology, its performance, its potential and the companies developing and producing the materials. Copyright © 2003 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: The synthesis and properties of carbazole-containing polymers are reviewed with 451 references in this paper, including polymers with pendant carbazolyl groups, polymers containing electronically isolated carbonazole moieties in the main chain, polymer with π-conjugated main chain and polymers as well as carbazoleside-containing molecular glasses.

Journal ArticleDOI
TL;DR: In this article, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT), where the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding.

Journal ArticleDOI
TL;DR: In this article, the general methodology for the synthesis of polymer brushes from flat surfaces, polymers and colloids is summarized focusing on reports using ATRP and the morphology of ultrathin films from polymer brushes is discussed using atomic force microscopy (AFM) and other techniques to confirm the formation of nanoscale structure and organization.
Abstract: Atom transfer radical polymerization (ATRP) is a robust method for the preparation of well-defined (co)polymers. This process has also enabled the preparation of a wide range of polymer brushes where (co)polymers are covalently attached to either curved or flat surfaces. In this review, the general methodology for the synthesis of polymer brushes from flat surfaces, polymers and colloids is summarized focusing on reports using ATRP. Additionally, the morphology of ultrathin films from polymer brushes is discussed using atomic force microscopy (AFM) and other techniques to confirm the formation of nanoscale structure and organization. Formation of polymer brushes by ATRP.

Journal ArticleDOI
TL;DR: In this article, the authors discuss concepts and features that are relevant to the adsorption of neutral and charged polymers at equilibrium, including the type of polymer/surface interaction, the solvent quality, the characteristics of the surface, and the polymer structure.

Journal ArticleDOI
TL;DR: In this paper, the authors show that photovoltaic devices fabricated from blends of branched CdSe nanoparticles and a conjugated polymer give improved performance compared with devices made from nanorod/polymer blends.
Abstract: We show that photovoltaic devices fabricated from blends of branched CdSe nanoparticles and a conjugated polymer give improved performance compared with devices made from nanorod/polymer blends. The improvement is consistent with improved electron transport perpendicular to the plane of the film. Solar power conversion efficiencies of 1.8% were achieved under AM1.5 illumination for a device containing 86 wt % of nanoparticles.

Journal ArticleDOI
TL;DR: In this article, the authors used noncovalently functionalized, soluble single-walled carbon nanotubes (SWNTs) to construct composites with very low percolation threshold (0.05 − 0.1 wt
Abstract: Homogeneous carbon nanotube/polymer composites were fabricated using noncovalently functionalized, soluble single-walled carbon nanotubes (SWNTs). These composites showed dramatic improvements in the electrical conductivity with very low percolation threshold (0.05–0.1 wt % of SWNT loading). By significantly improving the dispersion of SWNTs in commercial polymers, we show that only very low SWNT loading is needed to achieve the conductivity levels required for various electrical applications without compromising the host polymer’s other preferred physical properties and processability. In contrast to previous techniques, our method is applicable to various host polymers and does not require lengthy sonication.

Journal ArticleDOI
TL;DR: In this paper, a simple plasma treatment is demonstrated on PC and EPDM, respectively, to adjust the gas type and the plasma conditions on the polymer type to minimize degradation and aging effects.
Abstract: Different plasma treatments in a rf discharge of Ar, He, or N 2 are used to etch, cross-link, and activate polymers like PC, PP, EPDM, PE, PS, PET and PMMA. Due to the numerous ways a plasma interacts with the polymer surface, the gas type and the plasma conditions must be adjusted on the polymer type to minimize degradation and aging effects. Wetting and friction properties of polymers can be improved by a simple plasma treatment, demonstrated on PC and EPDM, respectively. However, the deposition of ultra-thin layers by plasma enables the adjustment of wetting properties, using siloxane-based or fluorocarbon films, and further reduction of the friction coefficient, applying siloxane or a-C:H coatings. Nevertheless, the adhesion of plasma-deposited coatings should be regarded, which can be enhanced by depositing a graded layer.

Journal ArticleDOI
TL;DR: In this paper, a series of poly(butylene succinate) (PBS)/organically modified layered silicate (OMLS) nanocomposites were prepared using a simple melt intercalation technique.
Abstract: Understanding the structure−property relationship in polymer/layered silicate nanocomposites is of fundamental importance in designing materials with desired properties. To understand these relations in the case of poly(butylene succinate) (PBS)/organically modified layered silicate (OMLS) nanocomposites, we studied the rheological properties of these materials in detail, because the rheological behavior of polymer/OMLS nanocomposites is strongly influenced by their nanostructure and the interfacial characteristics. For this reason, a series of PBS/OMLS nanocomposites were prepared using a simple melt intercalation technique. Two different types of OMLS, montmorillonite (mmt) modified with octadecylammonium chloride and saponite (sap) modified with quaternary hexadecyl tri-n-butylphosphonium bromide, were used for the nanocomposite preparations. The structure of nanocomposites in the nanometer scale was characterized using wide-angle X-ray diffraction (WAXD) analyses and transmission electron microscopy (...

Journal ArticleDOI
TL;DR: In this article, transmission electron microscopy (TEM) and wide-angle X-ray diffraction (XRD) were used to characterize the nanoscale dispersion of the layered silicate.
Abstract: Several polymer-layered silicate (clay) nano- composites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide-angle X-ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene-g-maleic anhydride). The re- sults of this study reveal that the overall nanoscale disper- sion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d-spacings in intercalated systems but cannot always observe low clay loadings (5%) or be used as a method to identify an exfoliated nanocom- posite where no XRD peaks are present (constituting a neg- ative result). Most importantly, the study showed that XRD is not a stand-alone technique, and it should be used in conjunction with TEM. Our studies suggest that new defi- nitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. © 2002 Wiley Periodicals, Inc.* J Appl Polym Sci 87: 1329 -1338, 2003

Journal ArticleDOI
TL;DR: In this paper, a direct mixing strategy has been demonstrated for the first time that allows fast (e.g., 0.5 h) synthesis of bulk quantity of thermally stable and highly porous metal-organic coordination polymers (MOCP) nanocrystals (30-150 nm diameter) at room temperature with high yield.

Journal ArticleDOI
TL;DR: In this paper, the authors reported the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L1ZnOEt)2 (L 1 = 2,4-di-tert-butyl-6-{[(2‘-dimethylaminoethyl)methylamin]methyl}phenolate).
Abstract: We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L1ZnOEt)2 (L1 = 2,4-di-tert-butyl-6-{[(2‘-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L1ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded Mn as high as 130 kg mol-1. The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L1ZnOEt to be distinguished and the empirical rate law to be elucidated, −d[LA]/dt = kp[L1ZnOEt][LA]. These studies also showed ...

Journal ArticleDOI
TL;DR: The temperature, pH, glucose concentration, NaCl concentration, and operating atmosphere dependence of the power output of a compartment-less miniature glucose-O(2) biofuel cell, comprised only of two bioelectrocatalyst-coated carbon fibers, is reported.
Abstract: We report the temperature, pH, glucose concentration, NaCl concentration, and operating atmosphere dependence of the power output of a compartment-less miniature glucose-O(2) biofuel cell, comprised only of two bioelectrocatalyst-coated carbon fibers, each of 7 micro m diameter and 2 cm length (Mano, N; Mao, F; Heller, A J Am Chem Soc 2002, 124, 12962) The bioelectrocatalyst of the anode consists of glucose oxidase from Aspergillus niger electrically "wired" by polymer I, having a redox potential of -019 V vs Ag/AgCl That of the cathode consists of bilirubin oxidase from Trachyderma tsunodae "wired" by polymer II having a redox potential of +036 V vs Ag/AgCl (Mano, N; Kim, H-H; Zhang, Y; Heller, A J Am Chem Soc 2002, 124, 6480 Mano, N; Kim, H-H; Heller, A J Phys Chem B 2002, 106, 8842) Implantation of the fibers in the grape leads to an operating biofuel cell producing 24 micro W at 052 V

Journal ArticleDOI
TL;DR: A new technique of combining the gel-casting and polymer sponge methods is introduced in this study to prepare macroporous hydroxyapatite scaffolds, which provides a better control over the microstructures of scaffolds and enhances their mechanical properties.

Journal ArticleDOI
TL;DR: In this article, the force required to separate a carbon nanotube from a solid polymer matrix was measured by performing reproducible nanopullout experiments using atomic force microscopy, and the results indicated that the polymer matrix in close vicinity of the carbon-nanotube is able to withstand stresses that would otherwise cause considerable yield in a bulk polymer specimen.
Abstract: The force required to separate a carbon nanotube from a solid polymer matrix has been measured by performing reproducible nanopullout experiments using atomic force microscopy. The separation stress is found to be remarkably high, indicating that carbon nanotubes are effective at reinforcing a polymer. These results imply that the polymer matrix in close vicinity of the carbon nanotube is able to withstand stresses that would otherwise cause considerable yield in a bulk polymer specimen.

Journal ArticleDOI
TL;DR: In this article, the interaction enthalpy between all components using special compatibilisation agents for the two intrinsically non-miscible materials is adjusted using a route block or graft copolymers, which leads to a separation of the mineral into single particles and a subsequent homogeneous incorporation of these particles into the polymer matrix material.