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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
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


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.

834 citations


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.

715 citations


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.

702 citations


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.

699 citations


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 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 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: 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.

Journal ArticleDOI
TL;DR: The role of crystal plasticity in achieving high toughness is addressed in this article, where two possibilities of the modification of crystal thickness are described: increase in the crystal thickness and a reduction in the number of mobile dislocations in polymer crystals, and two examples of efficient toughening in multicomponent polypropylene systems connected with cavitation are described.

Journal ArticleDOI
TL;DR: In this paper, the effects of the composition, such as the amounts of clay, polymer, and water content in DMAA-NC gels, on the tensile mechanical properties were investigated in detail.
Abstract: Nanocomposite type hydrogels (DMAA-NC gels) consisting of organic (polymer)/inorganic (clay) networks were prepared by in-situ free-radical polymerization of N,N-dimethylacrylamide (DMAA) in the presence of inorganic clay in aqueous solution. The composition of the NC gels could be controlled directly by altering the composition of the initial reaction mixture. The resulting DMAA-NC gels were mostly uniform and transparent, irrespective of their clay and polymer contents. From DSC, X-ray, TEM, and tensile mechanical measurements, the network structure was established. Contrary to conventional chemically cross-linked hydrogels (DMAA-OR gels) prepared by chemical cross-linking with a difunctional monomer, DMAA-NC gels exhibit superb mechanical properties with astonishingly large elongations at break, near to or greater than 1500%. The effects of the composition, such as the amounts of clay, polymer, and water content in DMAA-NC gels, on the tensile mechanical properties were investigated in detail. With inc...

Journal ArticleDOI
TL;DR: Chiral aluminum isopropoxides based on enantiopure or racemic cyclohexylsalen ligand (Jacobsen ligand) have been prepared and employed for stereoelective/stereoselective ring-opening polymerization of lactide in toluene at 70 degrees C.
Abstract: Chiral aluminum isopropoxides based on enantiopure or racemic cyclohexylsalen ligand (Jacobsen ligand) have been prepared and employed for stereoelective/stereoselective ring-opening polymerization of lactide in toluene at 70 °C. The kinetics, selectivity of the catalysts, and microstructure of the obtained polylactides, using different combinations of lactide enantiomers and catalysts, were determined. In all cases, polylactides of controlled molecular weight, low polydispersity, and defined end groups were obtained. The polymerizations are first-order in both monomer(s) and catalyst. (R,R)-CyclohexylsalenAlOiPr [(R,R)-1] polymerizes l-lactide significantly faster than d-lactide with a rate constant ratio kl/kd of ∼14. The polymerization of rac-lactide using (R,R)-1 yields crystalline polymers, for which a selectivity factor of ∼5.5 could be calculated up to 50% conversion based on the optical purity of the isolated polymers. The polymerization of a l-lactide/d-lactide (molar ratio: 80/20) mixture by (R...

Journal ArticleDOI
TL;DR: In this paper, the use of binary solvent mixtures in which one of the components is a ligand for the nanocrystals is effective in controlling the dispersion of nanocrystal in a polymer.
Abstract: We have shown recently that the use of high-aspect-ratio inorganic nanorods in conjunction with conjugated polymers is a route to obtaining efficient solar cells processed from solution. Here, we demonstrate that the use of binary solvent mixtures in which one of the components is a ligand for the nanocrystals is effective in controlling the dispersion of nanocrystals in a polymer. By varying the concentration of the solvent mixture, phase separation between the nanocrystal and polymer could be tuned from micrometer scale to nanometer scale. In addition, we can achieve nanocrystal surfaces that are free of surfactant through the use of weak binding ligands that can be removed through heating. When combined, the control of film morphology together with surfactant removal result in nanorod–polymer blend photovoltaic cells with a high external quantum efficiency of 59 % under 0.1 mW cm–2 illumination at 450 nm.

Journal ArticleDOI
TL;DR: The mesoporous titania films were chosen because they have pores with a diameter slightly less than 10 nm, which is the exciton diffusion length in many conjugated polymers, and because they provided continuous pathways for electrons to travel to an electrode after electron transfer has occurred as mentioned in this paper.
Abstract: We have made photovoltaic cells by infiltrating the conjugated polymer regioregular poly(3-hexylthiophene) into films of mesoporous titania, which are self-assembled using a structure directing block copolymer. The mesoporous titania films were chosen because they have pores with a diameter slightly less than 10 nm, which is the exciton diffusion length in many conjugated polymers, and because they provide continuous pathways for electrons to travel to an electrode after electron transfer has occurred. The photovoltaic cells have an external quantum efficiency of 10% and a 1.5% power conversion efficiency under monochromatic 514 nm light. Experiments that vary the amount of polymer in the titania films suggest that the performance of the cells is limited by poor hole transport in the polymer.

Journal ArticleDOI
01 Dec 2003-Polymer
TL;DR: In this article, the CNT-polymer interfacial shear stress (at 0 K) of about 138 and 186 MPa, respectively, for CNT/polystyrene (PS), was calculated.

Journal ArticleDOI
TL;DR: Compared with commonly used porosifying methods such as sintering, compression moulding combined with salt leaching, and freeze-drying, this process allows excellent control over pore size and porosity and yields scaffolds with a much more homogeneous pore morphology.

Journal ArticleDOI
TL;DR: The academic and industrial aspects of the preparation, characterization, mechanical and materials properties, crystallization behavior, melt rheology, and foam processing of pure polylactide (PLA) and PLA/layered silicate nanocomposites are described in this article.
Abstract: The academic and industrial aspects of the preparation, characterization, mechanical and materials properties, crystallization behavior, melt rheology, and foam processing of pure polylactide (PLA) and PLA/layered silicate nanocomposites are described in this feature article. Recently, these materials have attracted considerable interest in polymer science research. PLA is linear aliphatic thermoplastic polyester and is made from agricultural products. Hectorite and montmorillonite are among the most commonly used smectite-type layered silicates for the preparation of nanocomposites. Smectites are a valuable mineral class for industrial applications because of their high cation exchange capacities, surface area, surface reactivity, adsorptive properties, and, in the case of hectorite, high viscosity, and transparency in solution. In their pristine form, they are hydrophilic in nature, and this property makes them very difficult ot disperse into a polymer matrix. The most common way to overcome this difficulty is to replace interlayer cations with quaternized ammonium or phosphonium cations, preferably with long alkyl chains. In general, polymer/layered silicate nanocomposites are of three different types: (1) intercalated nanocomposites, in which insertion of polymer chains into the layered silicate structure occurs in a crystallographically regular fashion, regardless of polymer to layered silicate ratio, with a repeat distance of few nanometer; (2) flocculated nanocomposites, in which intercalated and stacked silicate layers are sometimes flocculated due to the hydroxylated edge-edge interactions between the silicate layers; (3) exfoliated nanocomposites, in which individual silicate layers are uniformly distributed in the polymer matrix by average distances that totally depend on the layered silicate loading. This new family of composite materials frequently exhibits remarkable improvements in its material properties when compared with those of virgin PLA. Improved properties can include a high storage modulus both in the solid and melt states, increased flexural properties, a decrease in gas permeability, increased heat distortion temperature, an increase in the rate of biodegradability of pure PLA, and so forth.

Journal ArticleDOI
TL;DR: Single-walled carbon nanotubes were functionalized along their sidewalls with phenol groups using the 1,3-dipolar cycloaddition reaction, leading to the production of high molecular weight polymers with relatively large polydispersities.
Abstract: Single-walled carbon nanotubes were functionalized along their sidewalls with phenol groups using the 1,3-dipolar cycloaddition reaction. These phenols could be further derivatized with 2-bromoisobutyryl bromide, resulting in the attachment of atom transfer radical polymerization initiators to the sidewalls of the nanotubes. These initiators were found to be active in the polymerization of methyl methacrylate and tert-butyl acrylate from the surface of the nanotubes. However, the polymerizations were not controlled, leading to the production of high molecular weight polymers with relatively large polydispersities. The resulting polymerized nanotubes were analyzed by IR, Raman spectroscopy, DSC, TEM, and AFM. The nanotubes functionalized with poly(methyl methacrylate) were found to be insoluble, while those functionalized with poly(tert-butyl acrylate) were soluble in a variety of organic solvents. The tert-butyl groups of these appended polymers could also be removed to produce nanotubes functionalized wi...

Journal ArticleDOI
13 Sep 2003-Langmuir
TL;DR: In this article, a set of poly(l-lysine) grafted with poly(ethylene glycol) (PLL-g-PEG), a polycationic copolymer that is positively charged at neutral pH, spontaneously adsorbs from aqueous solution onto negatively charged surfaces.
Abstract: Poly(l-lysine) grafted with poly(ethylene glycol) (PLL-g-PEG), a polycationic copolymer that is positively charged at neutral pH, spontaneously adsorbs from aqueous solution onto negatively charged surfaces, resulting in the formation of stable polymeric monolayers and rendering the surfaces protein-resistant to a degree related to the PEG surface density. A set of PLL-g-PEG polymers with different architectures was synthesized. The grafting ratio, g, of the polymer, defined as the ratio of the number of lysine monomers to the number of PEG side chains, was systematically varied between 2 and 23, and PEG molecular weights of 1, 2, and 5 kDa were used. The polymers were adsorbed onto niobium oxide-coated substrates, leading to highly different but well-controlled PEG surface densities with maximal values of 0.9, 0.5, and 0.3 chains/nm2 for the three PEG molecular weights, respectively. Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) was used in conjunction with the in situ optical waveguide light...

Journal ArticleDOI
TL;DR: In this article, the authors provide a general coverage of various scientific aspects of the WSP-metal ion interactions in aqueous solution and their applications, including fundamental aspects on synthesis of water-soluble polymers.

Journal ArticleDOI
TL;DR: In this article, the reaction of PF 5 and EC/linear carbonates to carbonate solvents and how these reactions lead to the formation of products that impact the performance of Li-ion batteries is investigated.