bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion dissociation and conduction of Nafion/modified oligo(oxyethylene) composite films
Authors: Wang Yun Pu , Feng Han Yu , Fu Zheng Sheng , Tsuchida Eishun , Takeoka Shinji , Ohta Tomoyuki
Published: April 2003

In order to improve the ionic conductivity of solid polymer electrolyte by controlling ion(alkali metal ion)–dipole(ether oxygen) interaction, two kinds of modification were adopted on oligo(oxyethylene) (OOE). One is the capping of terminal hydroxyl groups of OOE with methyl or acetyl groups. The other is the replacement of the center ethylene group of OOE with methylene or propylene group. Ion–dipole interaction was analyzed by measuring the ion dissociation, ion conduction and Tg of Nafion/modified OOE composite films. The modification of the end groups was more effective than that of the center group in increasing ionic conductivity. The methyl group is superior to the acetyl group as the end group of OOE for lithium ion conduction.
Preparation of dehydrated powder of hemoglobin vesicles
Authors: Wang Lin , Takeoka Shinji , Tsuchida Eishun , Tokuyama Satoru , Mashiko Takahiro , Satoh Tadashi
Published: April 2003

The carbonyl hemoglobin (CO‐Hb), which was used to prevent denaturation (metHb) during the preparation of samples, was encapsulated into lipid vesicles constituted from unsaturated phospholipid, cholesterol and unsaturated fatty acid. Unsaturated components were polymerized by γ‐irradiation to enhance the stability of bilayer membrane. An aqueous dispersion of resulting Hb vesicles was freeze‐dried in the presence of saccharides (50–200 mM) to obtain a dehydrated powder of Hb vesicles. Change in the vesicle size, the leakage of encapsulated Hb and the oxidation of Hb to metHb were not observed. Therefore, the long‐term storage of Hb vesicles can be realized as a dry powder.
Shear flow experiments in an assembly of gel beads and modelling of bingham behavior
Authors: Lequeux François , Grosshans Daniel , Hocquart Roger
Published: April 2003

In this paper, we present a rheological study of a compact layer of highly swollen gel beads. The flow regimes of these systems are modelled by an elastic sinusoid moving in a Newtonian fluid. This model predicts a yield stress varying with the square root of the elastic modulus of the gel bead. The slope at the origin (at zero velocity) of the flow curve is expected to depend only on geometrical parameters and on the solvent viscosity. The experimental data are in qualitative agreement with the theoretical predictions.
Positive working photoresists sensitive to visible light, II: poly{2‐arylpropyl‐2 and bis(p‐methoxyphenyl)methyl methacrylates}
Authors: Ohe Yasushi , Ichimura Kunihiro
Published: April 2003

Acid‐labile polymers of methacrylates of 2‐(p‐substituted phenyl)propanol‐2 and bis(p‐methoxyphenyl)methanol were evaluated as visible light sensitive positive‐type resists. The chemistry to form images is based on the cleavage of esters catalysed by an acid generated by photodecomposition of diphenyliodonium hexafluorophosphate sensitized by 2‐benzoyl‐3‐(p‐dimethylaminophenyl)‐2‐propenenitrile. A copolymer of bis(p‐methoxyphenyl)methyl methacrylate‐phenyl methacrylate exhibited a high photospeed upon exposure to 488 nm light when coupled with the iodonium salt and the dye, and was applicable to relief holography.
FT–IR microspectroscopy study of blends of ester functionalized ethylene–propylene copolymer with (vinylidene fluoride‐hexafluoropropene) elastomer
Authors: Benedetti E. , D'Alessio A. , Tong S. Y. , Ruggeri G. , Ciardelli F. , Moggi G. , Pianca M.
Published: April 2003

An ethylene—propylene (EPR) copolymer functionalized with (1,2‐dicarboethoxy)ethyl groups has been blended with a vinylidene fluoride—hexafluropropene elastomer (NML). The existence of intermolecular interactions involving mainly the carbonyl groups of the side chains of the functionalized copolymer and the methylene hydrogens of the fluoroelastomer through hydrogen bonding was shown by means of FT—IR spectroscopy. The structure and composition of some microdomains in the mixture was examined by means of FT—IR microspectroscopy.
Fast‐switching ferrolectric liquid crystalline polymers containing one or two centres of chirality in the side chain
Authors: Scherowsky Günter
Published: April 2003

In a liquid crystalline side chain polyacrylate containing one center of chirality in the terminal alkyl chain of the mesogenic part, switching times of 200–400 μs were measured in the SmC* phase. Below this phase an unidentified phase exists, which shows electroclinic‐like switching. The phase transition between those two phases can be shifted by applying an electric field.

At higher molecular weights three subphases emerge in the SmC* region. Variation of the spacer length revealed, for the first time, ferroelectric switching even at a spacer length of only two CH2 groups.

By shifting the centre of chirality into the spacer of the side group a polymer resulted, which shows electroclinic switching in the SmC* phase, changing to ferroelectric switching when the voltage is increased.

Incorporation of an oxirane ring as chiral building block into the spacer yielded a polymer that shows a sign inversion of the spontaneous polarization in the SmC* phase.

A polymer containing a dioxolane carbonic ester as chiral unit exhibits three switching states, with the third state existing at a low or zero electric field. This phenomenon is known for antiferroelectric liquid crystals.

By doping a racemic LC polymer with a chiral monomeric LC we induced a spontaneous polarization. Colored FLC polymers were obtained by two different approaches. In an FLC–dye copolymer, increasing switching speed in three different chiral smectic phases was observed when increasing the dye concentration.
Collective and molecular dynamics in ferroelectric liquid crystals: from low molar to polymeric and elastomeric systems
Authors: Kremer F. , Schönfeld A. , Hofmann A. , Zentel R. , Poths H.
Published: April 2003

Broadband dielectric spectroscopy delivers in the frequency range from 10 Hz to 1010 Hz two collective dielectric loss processes (soft and Goldstone modes) and one molecular relaxation (β‐relaxation). The soft mode and Goldstone mode are assigned to the fluctuation of the amplitude and the phase of the helical superstructure. The β‐relaxation corresponds to the libration (hindered rotation) of the mesogene around its long molecular axis. At the SmA–SmC* phase transition this process does not split or broaden, and the temperature dependence of its relaxation rate does not show any deviation from an Arrhenius‐like behavior. Its dielectric strength does not decline at the SmA–SmC* phase transition. These experimental findings are in contrast to the common explanation of the origin of the saturation polarization (“induced spontaneous polarization”), which is based on the existence of a “free” rotation inside the SmA phase and its strong hindrance in the ferroelectric SmC* phase. Furthermore, the high frequency results require a reformulation for the (generalized) Landau theory as applied to the SmA–SmC* phase transition. In comparing low molar mass and polymeric (elastomeric) FLC, the collective and molecular dynamics are qualitatively similar, independent of the molecular architecture (e.g. side‐chain, combined main‐ and side‐chain or crosslinked systems).
A novel method to determine the molecular weight of the oligomers of biodegradable polymer
Authors: Maniar Manoj L. , Advant Siddharth J. , Kalonia Devendra S. , Simonelli Anthony P.
Published: April 2003

The biodegradable polymers used in controlled release applications are primarily insoluble polymers which undergo chemical or enzymatic hydrolysis to form soluble monomeric or oligomeric units. To determine the endurance of the polymer after implantation or injection into the body it is important to determine the rate of elimination of the intermediates formed upon the hydrolysis of the polymer. It is essential to identify these intermediates before its elimination rate can be determined. Identification of these intermediates is a problem because they are difficult to isolate, and are thermally and hydrolytically unstable.

A new technique is proposed, taking advantage of the neighboring group effect on the hydrolysis of ionic and non‐ionic oligomers, to determine the molecular weight of unknown species that are formed upon hydrolysis of the polymer. The technique involves the determination of the specific acid and base catalytic rate constants. To demonstrate the technique, a time sequence synthesis was carried out to synthesize several oligomers that would be forming upon the hydrolysis of poly(butylene tartrate). Hydrolysis studies were conducted with these oligomers and the samples were analyzed by liquid chromtography. The observed rate constant for the hydrolysis under acidic and alkaline pH medium were calculated from the terminal slopes of the first order plot. The observed rate constants were further utilized to calculate the specific acid and base catalytic rate constants. These specific rate constants, along with the micro‐hydrogen and ‐hydroxyl ion catalytic rate constants, were used to determine the molecular weight of the intermediate species.

The molecular weight obtained from the kinetic parameters was in excellent agreement with the results obtained from fast atom bombardment mass spectrometry. The same type of analysis can be extended to any multifunctional group compound which has repeat units and can undergo a specific reaction which can be accurately measured.
Targeting polysaccharide–methotrexate conjugates to the rat brain
Authors: Sanzgiri Yeshwant D. , Blanton C. Dewitt , Gallo James M.
Published: April 2003

Delivery of drugs to brain tumors is difficult due to the impermeability, and variable nature of the blood/tumor barrier. Of the various strategies designed to improve drug uptake‐intracellularly and into the brain, cationic carriers seem to offer an advantage. In the current investigation cationic polysaccharide–methotrexate conjugates were examined in the rat. Conjugates were prepared from N,O‐carboxymethyl chitosan (NOCC) and 3H‐methotrexate (MTX) by two different synthetic schemes, resulting in NOCCMTX‐1 and NOCCMTX‐2. NOCCMTX‐1 appeared to have a higher degree of cross‐polymerization than NOCCMTX‐2. Each conjugate and free MTX were administered intra‐arterially in a retrograde manner in the external carotid artery at a MTX dose of 1 mg/kg as a constant rate infusion over 30 min. Animals were sacrificed at various times after administration, and blood and tissue samples collected, processed in a sample oxidizer, and then measured for radioactivity. Brain MTX concentrations were 18‐ and 12‐fold greater at 15 min and 3 hr, respectively, following NOCCMTX‐1 administration compared to free MTX treatment. However, NOCCMTX‐1 resulted in animal death at about 12 hr after administration. NOCMTX‐2 was found to be non‐toxic, yet did not increase brain MTX concentrations compared to free drug administrations after correction for MTX in residual blood. Further investigations are planned to combine the positive drug targeting effect of NOCCMTX‐1 with the safety of NOCCMTX‐2.
Stimulation of trigeminal motoneurons by in vivo implantation of glutamate‐impregnated microspheres
Authors: Byrd Kenneth E. , Domb Abraham J. , Sokoloff Alan J. , Hamilton‐Byrd Elizabeth L.
Published: April 2003

The objective of this study was to alter biomechanical forces generated by the muscles of mastication that affect the growth of the craniofacial skeleton through the implantation of neurotransmitter microspheres to stimulate trigeminal motoneurons (TMNe) in vivo. Polyanhydride microspheres containing L‐glutamate were stereotaxically implanted 170–920 μm rostral to the left‐side trigeminal motor nucleus (TMNu) in 17 Sprague–Dawley rats at 33–38 days old. Seven rats received blank‐microsphere implants and two rats had empty delivery system penetration as controls. All rats were killed 10–14 days postsurgical for dissection, brain histology, osteometric data, and SEM analyses. Dimensions of the facial skeletons of glutamate‐microsphere rats showed significant (P<0.01, P<0.05) differences when compared to control animals. Glutamate‐microsphere animals also demonstrated significant (P<0.01) differences between the dimensions of their implant‐and nonimplant‐side facial skeletons. SEM analyses indicated that glutamate‐microsphere rats had greater implant‐side wear of their mandibular incisors compared to blank‐microsphere or delivery system controls. The skeletal alterations in the glutamate‐microsphere rats are hypothesized to be due to increased implant‐side TMNe and masticatory muscle activity patterns.
The effect of fiber coating on the tensile properties of ionomer‐based composites
Authors: Papaspyrides Constantine D. , Poulakis John G.
Published: April 2003

Asbestos fibers, of the chrysotile variety, were coated with a thin polyamide film by an in situ polycondensation technique. Ionomer‐based composites were prepared containing the so‐modified asbestos fibers in a random in‐plane orientation; results of testing the tensile properties of these asbestos/polyamide/ionomer composites are presented. Parameters investigated comprise the asbestos content in the composite and the polyamide content deposited on asbestos. A significant improvement in the tensile performance was established, especially at the intermediate polyamide content of 3.4 phr. The behavior is discussed in terms of possible interactions between the phases present in the composite material.
A new approach to the design of surface treatments for reinforcing agents
Authors: Economy James , Jung Holger , Andreopoulos Andreas G.
Published: April 2003

A new approach for design of improved interfacial bonding between carbon fibers and polymeric matrices is described. In this method the affinity of surface‐treated carbon fibers to various polymer matrices is simulated by analyzing the adsorption characteristics of model compounds, typical of the polymer units, onto very high surface area carbon fibers. The affinity can be evaluated by the use of Thermogravimetric Analysis (TGA) to measure adsorption–desorption characteristics. Since high surface area, activated carbon fibers (ACF) can be chemically treated to obtain acidic, basic, nonpolar or highly polar surfaces, it should be possible to assess the interactions of chemically modified surfaces with model compounds such as methanol (MeOH), acetone, dimethylformamide (DMF), dimethylether, tetrahydrofuran (THF) and water. Some preliminary results are presented, indicating that surface treatments for carbon fibers other than oxidation may lead to enhanced bonding with polymeric matrices.
Diacetylene‐containing polymers, II. Polyesters and polyurethanes containing m,m′‐butadiynylenedibenzyl groups
Authors: Estrada Mirna R. , Burillo Guillermina , Ogawa Takeshi
Published: April 2003

Diacetylene‐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

Electroluminescent 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

The 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

Poly(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

Network 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

A 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

Redox‐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

A 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

Hemoglobin (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

New 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

Solid 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

Two 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

A 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

The 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

Polyolefins 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

Metallocene‐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

Results 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

Structured 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

The 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

Photoinduced 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+.
Sulfonated polypropylene ionomers
Authors: Dassaud J. P. , Gallot B. , Guyot A. , Spitz R. , Beautemps J. P. , Williams C. , Bourgaux C. , Eisenberg A.
Published: April 2003

Polypropylene ionomers have been prepared by sulfonation of copolymers of propene and 7 methyl, 1‐6 octadiene, followed by neutralization to cesium salts. Both WAXS and SAXS were used to study the morphology of the samples, while their thermal properties were studied by DSC and their mechanical properties by DMTA. The sulfonation process is shown to cause a further drop in crystallinity in addition to the effect of comonomer incorporation. Ion clustering is observed when the extent of sulfonation is high enough, the limit being dependent on the copolymer composition. The ion pairs which are not incorporated into the cluster cause a small‐angle upturn in the WAXS pattern. The mechanical properties are strongly affected by the drop in crystallinity, but may be partly recovered due to ion clustering. No disruption of the ion clusters is observed before thermal decomposition of the polymer.
Densely crosslinked liquid single‐crystal elastomers
Authors: Küpfer Jürgen , Nishikawa Etsushi , Finkelmann Heino
Published: April 2003

A series of liquid single‐crystal elastomers (LSCE) with different crosslinking densities were synthesized. The influence of the crosslinking density on the macroscopic properties (e.g. swelling, thermoelastic behavior and birefringence) and the phase behavior was studied. It is shown that densely crosslinked duromers are available which possess no clearing temperature and exhibit relatively high birefringence at high temperature.
Recent developments in polymeric charge transfer complexes
Authors: Natansohn Almeria
Published: April 2003

The recent literature on polymeric charge transfer complexes is reviewed with emphasis on the author's own work. After a definition of the area and a survey of investigations on the spatial arrangement of donor and acceptor sites in the solid state, a variety of applications of these complexes is presented. Electrically conductive polymers are excluded. These applications are: compatibilization of polymer blends, liquid crystalline supramolecular organization, new developments in photo‐conductivity, electroluminescence, nonlinear optical properties, photorefractivity and reversible optical storage.
Crosslinked poly(N‐isopropylacrylamide) gel for electrophoretic separation and recovery of substances
Authors: Yoshioka Hiroshi , Mori Yuichi , Tsuchida Eishun
Published: April 2003

Crosslinked poly(N‐isopropylacrylamide) gel was tested on the feasibility for a preparative electrophoretic matrix. Horse heart myoglobin and bovine hemoglobin were well separated on the gel matrix electrophoretically by molecular sieving effect of the gel network. Relative mobilities of those proteins in the gel were larger than those in a crosslinked polyacrylamide gel of the same polymer concentration. After the separation, the protein‐containing portion of the gel underwent swelling at 4°C and deswelling at 37°C, alternatively. As a result of the deswelling, each protein was recovered in a discharged solution out of the gel at almost 100% yield.
Orientation of a chiral smectic C elastomer by mechanical fields
Authors: Semmler Klaus , Finkelmann Heino
Published: April 2003

It is well known that, with respect to the director, nematic elastomers can be macroscopically aligned by uniaxial mechanical fields. Extending this method to a chiral smectic C elastomer, depending on the experimental set‐up either smectic layer orientation or director orientation parallel to the stress axis occurs. In order to align the director and the smectic layers a biaxial mechanical field (e.g. shear field) consistent with the phase symmetry has to be used to achieve a macroscopically uniform orientation of the untwisted smectic C* structure.
Photoelectrical properties of Langmuir–Blodgett films of poly(methyl phenylsilane)s
Authors: Brynda E. , Koropecký I. , Kmínek I. , Nes̆pu̇rek S. , Schnabel W.
Published: April 2003

Langmuir–Blodgett (LB) films were prepared from poly(methylphenylsilane) bearing electron acceptor π‐conjugated substituents. The small limiting area (0.078 nm2) per one repeating unit of polysilane (PSi) in monomolecular film and the large thickness of the film (6 nm) suggest that the polymer chains are not fully spread on water surface. The electrical and photoelectrical properties of Al/LB film/Au sandwich cells containing various numbers of the polysilane layers were studied. Holes were transported from the Al electrode through the LB film to the Au electrode when the light was absorbed by the polysilane. The highest photovoltaic effect occurred in the first monolayer of polysilane at the Al contact. The cell resistivity and the photovoltage were decreased by parallel conductance of defects in the films consisting of small numbers of PSi layers.
Cure behavior and thermal stability of an epoxy: new bismaleimide blends for composite matrices
Authors: Kim Dae Su , Han Mi Jung , Lee Jae Rock , Chang Ji Young
Published: April 2003

A new bismaleimide (BMI) resin was synthesized to formulate epoxy(tetraglycidyl diaminodiphenyl methane; TGDDM) – bismaleimide thermoset blends for composite matrix applications. 4,4′‐diaminodiphenyl methane (DDM) was used as an amine curing agent for the TGDDM. A Fourier transform infrared (FTIR) spectroscopy was employed to characterize the new BMI resin. Cure behavior of the epoxy–BMI blends was studied using a differential scanning calorimeter (DSC). DSC thermograms of the thermoset blends indicated two exothermic peaks. The glass transition temperature of the thermoset blends decreased with BMI content. Thermogravimetric analysis (TGA) was carried out to investigate thermal degradation behavior of the cured epoxy–BMI thermoset blends. The new BMI resin reacted partially with the DDM and weak intercrosslinking polymer networks were formed during cure of the thermoset blends.
Use of functional microgels with vinyl groups to accelerate photopolymerization reaction
Authors: Sasa Nobumasa , Sato Akira , Yamaoka Tsuguo
Published: April 2003

Three types of functional microgels with vinyl groups on their surface were prepared. For the first type, the counter anion from clorin was exchanged with β‐methacryloylethyl sulfonic acid, styrene sulfonic acid or allyl sulfonic acid in a microgel with ammonium anions. For the second and third types, a quaternization with N,N‐dimethylaminoethyl methacrylate of 3‐chloro‐2‐hydroxypropyl methacrylate in the presence of microgel particles was prepared by emulsion copolymerization of styrene, chloromethylstyrene or N,N‐dimethylamino‐methylbenzene, and divinylbenzene. The resulting samples show good dispersibility in organic solvents without an emulsifier.

A functional microgel‐based photopolymer combined with an acrylate monomer and ultraviolet (UV) or visible (VIS) light‐absorbing photoinitiators provides oleophilic images when exposed to UV or VIS light and developed in tap water. This photopolymer has a higher sensitivity than those of photopolymers based on microgels with an analogous composition but without vinyl groups. Photopolymers pepared by using functional microgels with a methacryloyl group exhibited a higher rate of polymerization (Rp) than that of photopolymers based on microgels without a vinyl group. The Rp of photopolymers prepared by using a functional microgel with either an allyl group or vinylphenyl group was nearly equal to that of photopolymers based on microgels with ammonium ions. Their high sensitivities are attributed to the rapid photopolymerization in the methacryloyl group.

To determine how the photoreaction mechanism enhances sensitivity, the photoreaction products were investigated using a model photopolymerization system. It was found that the gelation reactions enhancing sensitivity are predominantly the polymerization and crosslinking ones when a microgel with the methacryloyl group is used, and the graft copolymerization with acrylate monomers when a microgel with either the allyl group or vinylphenyl group is used.
High‐performances membranes for pervaporation I. Poly(vinyl alcohol)–poly(N‐vinyl pyrrolidone) blends
Authors: Nguyen Quang‐Trong , Ping Zhenghua , Néel Jean
Published: April 2003

Dense membranes were prepared from poly(vinyl alcohol)–poly(N‐vinyl pyrrolidone) (PVA–PVP) blends of different compositions and studied in swelling and dehydration by pervaporation of three organic solvents contaminated by 5 wt% water. The swelling generally increases with the PVP content. No extraction occurs in water–tetrahydrofuran (THF) and water–methyl ethyl ketone (MEK) mixtures. In ethanol containing 10 wt% of water, there is no extraction for blends containing less than 40 wt% PVP and an increasing extraction beyond this PVP content. The pervaporation flux of the water–ethanol mixture increases drastically at the same threshold whereas the water permselectivity falls to a low level. The values of the diffusion and permeability coefficients determined from transient permeation of the test water–ethanol mixture exhibit a similar sudden increase at the same PVP content threshold. This singular behavior of the blend membranes is interpreted by a strong affinity of the PVP component to ethanol, combined with a disappearance of crystallites in the blend at this threshold. Consequently the amorphous membrane can swell freely according to the affinity of the PVP component, leading to the observed behavior.