bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diacetylene‐containing polymers, II. Polyesters and polyurethanes containing m,m′‐butadiynylenedibenzyl groups
Authors: Estrada Mirna R. , Burillo Guillermina , Ogawa Takeshi 
Published: April 2003

AbstractDiacetylene‐containing polyesters and polyurethanes were prepared by the reaction of m,m‐butadiynylenedibenzyl alcohol with isophthaloyl chloride, sebacoyl chloride, hexamethylene diisocyanate and 2,4‐tolylene diisocyanate. Their thermal behavior was studied by optical microscope and differential scanning calorimetry (DSC). The polyesters were crystalline. The polyurethane prepared from hexamethylene diisocyanate and polyphthalates crystallized on cooling from their melts. All turned a reddish brown color on heating at temperatures above 200°C, and prolonged heating led to a black resin, but thermal decomposition could not be avoided. Irradiation by γ‐ray and UV light at room temperature deepened the color of the films, but the polymerization of the diacetylene groups was not appreciable. Simultaneous heating and irradiation was necessary to obtain transparent, amorphous, wine red colored films.
Plasma‐polymerized carbon disulfide films as a hole transport layer in organic electroluminescent devices
Authors: Kido Junji , Guo Yaohua , McBreen James , Nagai Katsutoshi , Okamoto Yoshiyuki 
Published: April 2003

AbstractElectroluminescent devices were fabricated using plasma‐polymerized carbon disulfide films, poly(CS2), and tris(8‐quinolinolato)aluminum(III) complex, Alq, as the hole transport layer and the emitting layer, respectively. A cell structure of glass substrate/indium–tin–oxide/poly(CS2/Alq/Mg/Ag) was employed. Smooth hole injection from the electrode through the poly(CS2) layer and concomitant electroluminescence from the Alq layer were observed. Green emission with a luminance of 250 cd/m2 was achieved at a drive voltage of 14 V.
Modulation of oxygen‐carrying capacity of artificial red cells
Authors: Wang Lin , Morizawa Kazuya , Tokuyama Satoru , Satoh Tadashi , Tsuchida Eishun 
Published: April 2003

AbstractThe oxygen‐carrying capacity of artificial red cells (ARC), which were prepared by encapsulating hemoglobin (Hb) into polymerized lipid vesicles, has been investigated in detail. It was found that the effects of inositol hexaphosphate (IHP) on the oxygen affinity of stromafree Hb and ARC are quite different. By co‐encapsulating IHP at a IHP:Hb molar ratio of 1.0, the oxygen affinity of the encapsulated Hb in ARC was decreased to such an extent that P50 was about 60–65 mmHg, and only about 70–80% of the encapsulated Hb could be oxygenated at an oxygen partial pressure (Po2) of about 100 mmHg. As pyridoxal 5‐phosphate (PLP) and chloride ions were coencapsulated instead of IHP, P50 and the Hill coefficient of the obtained ARC were adjusted to 25–30 mmHg and 2.5–2.8 respectively. The oxygen‐transporting efficiency of PLP‐modulated ARC was similar to or better than that of red blood cells.
Poly(styrene) coating of monodispersed colloidal metal oxides by grafting to hydrophilic macromer adsorbed on the surface
Authors: Yoshinaga Kohji , Yokoyama Takafumi , Kito Taketoshi 
Published: April 2003

AbstractPoly(styrene) (PST) coatings of monodispersed colloidal metal oxide particles by surface grafting to poly(N‐vinyl‐2‐pyrrolidone) (ST–PVP) or quaternized poly(4‐vinylpyridine) (ST‐PVPy(Me)) macromer, having a vinylphenylene end group, were investigated. Radical polymerization of styrene (ST) in ethanolic silica colloid in the presence of ST‐PVP successfully led to the formation of monodispersed PST/PVP copolymer/SiO2composites. The addition of divinylbenzene (DVB) to the reaction system gave SiO2 composites coated with crosslinked PST. Graft‐polymerization of ST to ST‐PVP also took place on TiO2, CeO2 and Al(OH)3 colloidal particles in ethanolic solution. However, ST‐PVPy(Me) adsorbed on colloidal silica did not effectively graft PST.
Synthesis of polymer electrolytes based on poly[2‐(2‐methoxyethoxy)ethyl glycidyl ether] and their high ionic conductivity
Authors: Kono Michiyuki , Furuta Katsuji , Mori Shigeo , Watanabe Masayoshi , Ogata Naoya 
Published: April 2003

AbstractNetwork polymer electrolytes based on poly[2‐(2‐methoxyethoxy)ethyl glycidyl ether] (PME2GE) were synthesized and characterized. The effects of crosslinking density, the introduction of ethylene oxide (EO) unit into the main chain by copolymerization, and the electrolyte (LiClO4) concentration on the ionic conductivity were explored. The random copolymer system improved the conductivity considerably compared with the polymer electrolytes previously obtained for network polymer systems and exhibited a high ionic conductivity of 10−4 S/cm at 40°C and 10−5 S/cm at 10°C, and even 3 X 10−7 S/cm at −20°C with optimization of the copolymer composition, the crosslinking density and the amount of LiClO4. The optimum composition was EO/ME2GE = 70/30 in molar ratio. The most preferable ratio of LiClO4 to etheric oxygen was in the range of 0.02–0.03.
Polymer networks for ionic conduction: a new family based on polysaccharide precursors
Authors: LeNest Jean‐François , Gandini Alessandro , Xu Lina , Schoenenberger Catherine 
Published: April 2003

AbstractA brief review is given of the fundamental features determining the behavior of amorphous polyethylene oxide‐based networks as polymer electrolytes containing ionic moieties in terms of two basic issues affecting the ultimate optimum ionic conductivity, viz. the factors determining the extent of ionic dissociation and those influencing the ionic mobility. These generalizations deduced from previous studies on a variety of systems allowed the elaboration of a new family of structures based on polysaccharides crosslinked with polyethylene oxide and grafted with polyether chains. The preliminary results dscribed in this paper are promising in view of the application of these materials in solid‐state batteries because of their good electrochemical properties combined with mechanical strength and film‐forming aptitude.
Effect of supporting electrolytes on the redox response of poly(xylyl viologen) and its polymer complex with poly(styrene sulfonate) in poly(ethylene oxide) oligomers
Authors: Ohno Hiroyuki , Ishikura Kenji 
Published: April 2003

AbstractRedox‐active poly(xylyl viologen) (PXV) was cast on a glassy carbon electrode and soaked into poly(ethylene oxide) (PEO) oligomers containing different supporting electrolytes. The obtained peak current was the function of the anion radius of the supporting electrolytes in PEO No cation dependence was observed. Anions migrated in the PXV matrix during the redox reaction and smaller anions gave a larger peak current, reflecting faster migration in the PXV matrix. However, when PXV was mixed with poly(styrene sulfonate) (PSS) on the carbon electrode to form a PXV–PSS complex, a similar voltammetric study revealed that only cations migrated in the PXV–PSS matrix during the redox reaction. Smaller cations gave larger peak currents for the PXV–PSS complex‐coated electrode in PEO oligomers. The ion radius dependence of the peak current in the PXV–PSS complex was smaller than that in the PXV system. This suggested that the PXV–PSS complex domain was polar but considerably smaller in the PEO oligomer.
Chemical preparation of conductive polypyrrole–polytetrafluoroethene composites
Authors: Lei Junting , Menon Vinod P. , Martin Charles R. 
Published: April 2003

AbstractA process for depositing a uniform, smooth and coherent film of conductive polypyrrole onto and into commercially available polytetrafluorethene (PTFE) tape is described. Adhesion is promoted by using Nafion (a perfluorosulfonate ionomer marketed by Du Pont) to create an interface between the polytetrafluoroethene and the polypyrrole. The composite shows low surface resistivity. Furthermore, the Teflon substrate can be oriented, and growth of polypyrrole on this oriented surface yields an oriented conductive polymer film.
Electron transfer reaction of poly(ethylene oxide)‐modified hemoglobin on the ITO electrode in solid polymer electrolytes
Authors: Ohno Hiroyuki , Yamaguchi Natsue , Watanabe Mika 
Published: April 2003

AbstractHemoglobin (Hb) was chemically modified with poly(ethylene oxide) (PEO) to prepare PEO‐Hb. This PEO‐Hb was cast onto the ITO (Indium Tin Oxide) electrode, and the modified electrode was then soaked in PEO oligomer solution containing 0.2 m KCI. PEO‐Hb was electrochemically reduced by applying a negative potential (ranging from −0.5 to −1.2 V vs. Ag). Electron transfer between adjacent PEO‐Hbs in the cast layer was considered to be slow. Higher salt concentration and more negative potential gave an effective reduction of PEO‐Hb in PEO oligomers. Re‐oxidation of the reduced PEO‐Hb was also carried out by giving positive potential. This redox reaction was confirmed as reversible by potential polarity charge. A similar redox reaction was carried out in dry poly(oligo(oxyethylene) methacrylate) containing KCl. Polymer electrolytes were revealed to be effective polymer solvents for the redox reaction of PEO‐modified hemoglobin cast on the ITO electrode.
Ionic conductivity and side chain relaxation in polyglutamates having oligo(ethylene oxide) chains
Authors: Watanabe Masayoshi , Aoki Sei , Sanui Kohei , Ogata Naoya 
Published: April 2003

AbstractNew polymer hosts to form polymer electrolytes, poly[methoxy‐oligo(ethylene oxide)‐L‐glutamate] (PMnEOG, n = 1, 2, 3 and 7, n stands for the number of ethylene oxide units), have been prepared in order to study the correlation between the side chain relaxation and the ionic conductivity of PMnEOG/LiClO4 complexes. The main chains of PMnEOGs form a rigid rod‐like structure (α‐helix structure) in the solid state both in the absence and the presence of LiClO4. The oligo(ethylene oxide) side chains begin to be mobile at temperatures lower than 0°C, while the rigid main chains do not move up to 100°C. The side chains show a preferential solvation of incorporated LiClO4. The ionic conductivity of 10−7−10−6S/cm is attained in PM3EOG/LiClO4 and PM7EOG/LiClO4 complexes at room temperature, where only the short side chain motion contributes to the ionic transport. The temperature dependencies of the side chain relaxation time and ionic conductivity increase with increasing the side chain length when the temperature dependencies are normalized by the temperatures based on the glass transition temperatures of the side chains, which indicates strong cooperation between the side chain motion and the ion transport. The possibility of fast ion transport by short side chain relaxation is discussed.
Ionically conductive thin polymer films prepared by plasma polymerization, part 9: Vapor‐phase preparation of solid polymer electrolytes composed of plasma polymer and lithium trifluoromethanesulfonate
Authors: Ogumi Zempachi , Uchimoto Yoshiharu , Endo Eishi , Yasuda Kazuaki , Takehara Zen‐ichiro 
Published: April 2003

AbstractSolid polymer electrolytes composed of plasma‐polymerized dimethyl‐2‐[(2‐ethoxy‐ethoxy)ethoxy]vinylsilane and thermal vapor‐deposited lithium trifluoromethanesulfonate have been prepared, and characterized using electron spectroscopy for chemical analysis (ESCA), Fourier transform/infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and electrochemical techniques. The obtained solid polymer electrolyte films of about 1 μm thickness were uniform and pinhole‐free. Room temperature conductivity of 8 × 10−6S/cm has been observed. This value depends on the substrate temperature during the plasma polymerization, and the variation of the ionic conductivity with temperature can be described by using a Williams–Landel–Ferry equation.
Poly(ethylene oxide)‐grafted polymers as materices for all‐solid batteries
Authors: Matsuda Yoshiharu , Morita Masayuki , Tsutsumi Hiromori 
Published: April 2003

AbstractTwo approaches for the preparation of highly ionconductive polymeric solid electrolytes have been followed: one was to add crown ether to cross‐linked poly(ethylene oxide) grafted methacrylate polymer swollen by lithium salt/propylene carbonate solution; and the other was to select crosslinked poly(dimethylsiloxane) with a low glass transition temperature for the matrix material. The conductivity of the former electrolyte was 3.2 × 10−3 S/cm even in the absence of crown ether at 20°C and increased to 4.0 × 10−3 S/cm by the addition of 15‐Crown‐5. The addition of crown ether in the electrolyte also affected the plating and stripping processes of Lion Ni substrate. The latter electrolyte was prepared as a single ion type polymeric solid electrolyte. The conductivity of the electrolyte was ca 10−5 S/cm at room temperature. The polarization curves of Li in the electrolyte were symmetric for O V vs. Li/Li+, therefore the plating and stripping of Li electrode in the electrolyte were reversible. The behavior of the latter electrolyte is preferable for rechargeable lithium battery use.
Polycaprolactone–poly(ethylene glycol) block copolymer, I: synthesis and degradability in vitro
Authors: Shen‐Guo Wang , Bo Qiu 
Published: April 2003

AbstractA new type of biodegradable polymer material, poly(caprolactone)–poly(ethylene glycol) block copolymer (PCL‐b‐PEG), was synthesized by means of direct copolycondensation of ε‐caprolactone with poly(ethylene glycol) in the presence of a Ti(OBu)4 catalyst. The degradability of the polycaprolactone was improved by introducing a PEG component into it. The degradation of PCL‐b‐PEG copolymer increase with a decreasing crystallinity of the copolymer, and can be controlled by adjusting the component ratio of the copolymer.
New materials from new catalysts
Authors: Sasaki Toshio , Ebara Takeshi , Johoji Hirofumi 
Published: April 2003

AbstractThe polyolefins, especially polypropylene and polyethylene, industry of today is very different from that of 10 years ago. The development of highly active and stereospecific catalysts, represented by Ti/Mg supported catalysts, have made the gas‐phase polymerization process practical.The trend in catalyst development is shifting from an emphasis on improving the stereospecificity and activity toward improving the polymer physical properties, processability and morphology.Many hybrid thermoplastic olefins, such as high‐impact copolymers, propylene–ethylene–butene terpolymers, and very low density polyethylene, have already been developed by utilizing the features of the gas‐phase polymerization process.These hybrid thermoplastic olefins cover a very broad range of products. They cannot be clearly identified as polyethylenes, polypropylenes or elastomers.Incidentally, metallocene catalysts for polyolefins have been under development for the past 15 years, and are now in the early stage of commercialization. These catalysts differ significantly from the conventional heterogeneous catalysts.They can polymerize not only ethylene, propylene and other linear α‐olefins, but also styrene, cycloolefins and functional monomers In addition, they can control the microstructure of polymer molecules by varying the transition metals and the cyclopentadienyl ligands.Because of these features, we have to be confident that the development of metallocene catalysts, or more widely homogeneous catalysts, may be a dominant force throughout the 1990s in the polyolefin industries.
Synthesis of polyolefin composition in the presence of supported catalysts
Authors: Dyachkovskii Fridrikh 
Published: April 2003

AbstractPolyolefins are basic materials in the plastics. Their application is limited by their low thermostability, adhesion, hardness and other physico‐mechanical properties. The following treatments are known to improve and modify polyolefin properties: the incorporation of inorganic or organic fillers with a greater hardness and rigidity into the polyolefin matrix, the grafting of functional groups to polyolefins, and crosslinking with the formation of a network structure in the polyolefin matrix. In the case of polymers and inorganic materials, the activation of their surface by the functionalizing and fixing of transition metals allows one to perform polymerization of monomers on a surface to obtain a polymer–polymer composites and a highly filled polymer–inorganic composites.
Novel polypropene materials derived from vinylidene‐terminated oligopropenes
Authors: Mülhaupt Rolf , Duschek Thomas , Fischer David , Setz Stefan 
Published: April 2003

AbstractMetallocene‐based homogeneous Ziegler–Natta catalysts produce mono‐olefin‐terminated oligopropenes with narrow molecular weight distributions, controlled stereoregularities, and molecular weights ranging from 100 to 30,000 g/mole in high yield slurry and solution processes. Steric and molecular weight control are influenced by metallocene structures, and by polymerization conditions such as temperature and propene concentration. Predominantly mono‐vinylidene‐terminated oligopropenes are attractive intermediates, and feedstock for the synthesis of a variety of polypropylene materials, including blends, block and graft copolymers. The key step is the chain end functionalization of the vinylideneterminated oligopropenes via double bond conversion reactions, followed by the controlled synthesis of polypropylene block and graft copolymers. In melt and solution processes the olefinic end groups have been converted into a variety of polar functional groups, e.g. hydroxy, carboxy, succinic anhydride, thiol and acrylic groups. The thiol‐terminated oligopropenes are chain transfer agents in radical methylmethacrylate polymerization with chain transfer constant measured to be 0.2. Acrylic monomers and styrene are grown onto the thiol end group via a chain transfer reaction, thus producing a family of block copolymers, e.g. poly(propene‐b‐methylmethacrylate) and poly(propene‐b‐styrene). As demonstrated by SEM fracture surface analysis, the poly(propene‐b‐styrene) block copolymers are efficient dispersing agents for compatibilizing polystyrene/polypropene (70/30) blends. Homo‐ and copolymerization of acrylic oligopropene macromonomers yield novel classes of graft copolymers with pendant isotactic or atactic oligopropene chains. Hydroxy‐terminated oligopropenes are useful initiators in caprolactone polymerization to form poly(propene‐b‐caprolactone) block copolymers. IR spectroscopic studies demonstrate that succinic anhydride‐terminated oligopropenes, obtained by ene‐type addition of maleic anhydride to the olefinic oligopropene end group, react with oligomeric diamine‐terminated polyamide‐6,6 in the melt to yield polypropene‐b‐polyamide‐6,6‐b‐polypropene triblock copolymers.
Synthesis of aramides in solutions of poly(vinylpyrrolidone)
Authors: Henze Andree , Berger Werner , Kummerlöwe Claudia , Kammer Hans‐Werner 
Published: April 2003

AbstractResults on polycondensation of poly(1.4 benzamide) (PBA) and 2.5.DCIPDAcoTPA in solutions of poly(vinylpyrrolidone) (PVP) will be presented. For polycondensation, the method of OGATA, using triphenylphosphine and hexachloroethane, and the low‐temperature solution polycondensation of dicarboxylic acid dichlorides and diamines, were applied. It is shown that the molar mass of PBA depends strongly on the PVP:PBA ratio. To explain this dependence, one has to take into account the phase behavior of the ternary rigid rod polymer/flexible coil polymer/solvent system and the influence of the matrix polymer. An enhancement of the molar mass of the PBA produced can be observed when the PVP:PBA is high enough to prevent an association of the PBA, i.e. when one stays in the isotropic one‐phase area of the phase diagram. Under these circumstances, it is possible to obtain one‐phase systems in nonsolvents for the aramides.
Core–shell morphology as a model for the study of gas permeation in composite systems
Authors: Correa C. Rodrigo , Klein Andrew 
Published: April 2003

AbstractStructured latex particles prepared by emulsion polymerization were used as a model to simulate the interphase region between two phases. Multiphase polymer films comprised of high and low permeability polymers of various compositions were used. The model system consisted of a poly(n‐butyl methacrylate) (PBMA) matrix and a discontinuous phase with core and shell morphology. The structured particle had a PBMA core and a vinylidene chloride – n‐butyl methacrylate (VDC–BMA) copolymer shell. The shell transport characteristics wer altered by changing the (VDC–BMA) copolymer molar ratio. The physical and transport properties for each individual component were measured. Nitrogen was the probe gas. Films used for permeation experiments were prepared by latex casting. The results showed that the morphology of a heterogeneous polymeric system and the transport characteristics of their components had a considerable effect on the magnitude of the transport properties. Experimental data also showed the dependence of the gas global permeability coefficient on the nature of the simulated interphase region, the shell, and the weight percentage of such interphase in the heterogeneous polymeric films. Upon increasing the VDC content in the VDC–BMA copolymer, the gas permeability decreased. The data were fitted to the electrical analogs of conductivity in composite systems. For the matrix filled with structured particles the overall permeability coefficient could best be described when the individual permeabilities were considered as the inverse resistances in parallel.
The structure of latex polystyrenes blends: dynamic properties of PS/XPS systems
Authors: Nemirovski N. , Narkis M. , Salovey R. 
Published: April 2003

AbstractThe dynamic behavior of latex polystyrene/crosslinked polystyrene (PS/XPS) systems has been studied. PS and XPS lattices were either physically blended, or used as seeds in semi‐continuous sequential two‐stage polymerizations. The Cox–Merz equation is not met by any PS/XPS system. Power‐law relaxation has been observed for the physically blended PS–b–XPS system in the terminal region. A two‐parameter equation suggested for polymers at the critical gel point fits the experimental data for XPS contents beyond 60%. This has been attributed to the formation of a “continuous” XPS network. This network is able to disrupt upon flow, due to the unique morphology of the XPS phase. It is possible that, for the sequential system with XPS seed particles, such a network may appear at a lower XPS content, due to a PS occlusion effect. A qualitative model is presented for these PS/XPS systems.
Photochemical generation of cationic lewis acids via deligation of metal‐sandwich complexes
Authors: Gamble Gary , Kutal Charles 
Published: April 2003

AbstractPhotoinduced loss of one or both ligands from bis(arene) metal complexes provides an attractive route to cationic Lewis acids that can function as initiators for polymerization and crosslinking reactions. In this article, we examine the spectroscopy, photochemistry and photoinitiation activity of two such complexes: Fe(mes)22+ (mes is mesitylene) and Cr(tol)2+ (tol is toluene). Acetonitrile solutions of Fe(mes)22+ undergo photochemical loss of both mesitylene rings to yield solvated Fe2+. The quantum efficiency of deligation ranges from 0.6 to 1.0 depending upon excitation wavelength, but is independent of complex concentration, solvent, oxygen concentration and excess counter‐ion. Reaction appears to occur from both ligand field and ligand‐to‐metal charge transfer excited states. Low thermal stability, however, limits the use of Fe(mes)22+ as a practical photoinitiator. Deligation of both arene rings also occurs upon 366 nm irradiation of Cr(tol)2+ in acetonitrile. The quantum efficiency for this process is 0.04 and is independent of oxygen concentration. Photoinitiated crosslinking and insolubilization occur in a thin film of COP (copolymer of glycidyl methacrylate and ethyl acrylate) containing Cr(tol)2+.