bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyelectrolytes containing dihyronicotiamide I. Electrostatic effect on the reduction in aqueous solution
Authors: Itoh Yoshihiro , Wakisaka Kazuyoshi , Matsuda Yutaka , Abe Koji , Senoh Saburo 
Published: April 2003

AbstractReduction of charged or uncharged substrates by a copolymer of N‐(p‐vinylbenzyl)‐1,4‐dihydronicotinamide and sodium styrene‐p‐sulfonate (PNAH) in aqueous solutions was investigated. Electrostatic interaction of PNAH with charged substrates led to a far more effective reduction of crystalviolet (CV) and a far less effective reduction of potassium ferricyanide (FeC) than the monomer model [N‐benzyl‐1,4‐dihydronicotinamide (BNAH)] system. In the PNAH‐CV system, in particular, a rapid reduction occurs by a first‐order process because of the remarkable concentration effect of the polymer. Furthermore, this reduction was not appreciably affected by an added salt, suggesting the presence of hydrophobic interaction between PNAH and CV.
Photopolymerization of cyclohexene oxide by use of o‐nitrobenzyl triphenylsilyl ether/aluminum compound catalyst. Dependence of catalyst activity on the structure of the silyl ether
Authors: Hayase Shuzi , Onishi Yasunobu , Suzuki Shuichi , Wada Moriyasu , Kurita Atushi 
Published: April 2003

Abstracto‐Nitrobenzyl triphenylsilyl ehther/aluminum compound has been previously shown by the authors to act as catalyst in the photopolymerization of epoxides. The dependence of the structure of the silyl ether on the catalyst activity was examined. There were two steps in the photopolymerization. The first step (“Step 1”) is photodecomposition of the silyl ether to silanol. The second step (“Step 2”) is the initiation of polymerization by silanol and the aluminum compound. The introduction of an electron withdrawing group, Cl, CF3, on the benzene ring bonded to Si made the quantum yield of Step 1 low, however, the rate of Step 2 was increased. The low quantum yield of Step 1 was explained in terms of the rate of electron transfer that is controlled by the relative electron density between the CH2 and NO2 in the o‐nitrobenzyl group. The acceleration of Step 2 was explained in terms of an increase in silanol acidity that was promoted by the introduction of an electron withdrawing group. The overall rate of the photopolymerizatiol depends to a greater degree on the rate of Step 2 than on that of Step 1.
The dependence of cyclopolymerizability of acrylic and methacrylic anhydrides on various conditions: New interpretation of temperature dependency of cyclization constant in radical cyclopolymerization of nonconjugated dienes
Authors: Matsumoto Akira , Terada Tsunehiko , Oiwa Masayoshi 
Published: April 2003

AbstractThe cyclization constant Kc in the radical cyclopolymerization of acrylic and methacrylic anhydrides was evaluated in detail under various conditions. No linear relationship between in Kc and 1/T was observed; cyclization was acceleratively enhanced at elevated temperatures. The Kc values also increased with decreased monomer concentration and increased solvent polarity. These increasing dependencies of Kc are ascribed to the increased significance of depropagation, demonstrating a new interpretation of the temperature dependence of the cyclization constant in the radical cyclopolymerization of nonconjugated dienes.
Functional polymers and sequential copolymers by phase transfer catalysis. XXII. Vinylidene fluoride–trifluoroethylene copolymers by surface modification of polyvinylidene fluoride
Authors: Hahn Bruce , Percec Virgil 
Published: April 2003

AbstractPolyvinylidene fluoride films and powders have been used to synthesize vinylidene fluoride‐trifluoroethylene copolymers. The synthetic procedure involves a phase transfer catalyzed heterogenous dehydrofluorination, followed by electrophilic chlorination or bromination. A phase transfer catalyzed displacement of bromine or chlorine by fluoride ion completes the synthesis. Dehydrofluorinations were up to 40% complete at room temperature and up to 100% complete at 90°C. Electrophilic chlorination of the resulting carbon–carbon double bonds were complete on both powder or films. The bromination of dehydrohalogenated polymers does not go to completion even when the reaction is carried out in solution. Displacement reactions were incomplete and resulted in further dehydrohalogenation when tetrabutylammonium hydrogen sulfate (TBAH) or 18‐crown‐6 and KF were used in organic solvents. Using TBAH, KHF2, and water, high degrees of displacement were achieved only on the brominated compounds. The chlorinated products gave both displacement and elimination.
Polymerization using palladium (II) salts. III. Polymerization of 4‐bromo‐4′‐ethynyl biphenyl
Authors: Trumbo D. L. , Marvel C. S. 
Published: April 2003

AbstractThe monomer 4‐bromo‐4′‐ethynyl biphenyl was synthesized and subsequently polymerized utilizing a bis (triphenylphosphine) palladium (II) chloride, copper (I) iodide, triphenylphosphine catalyst system in an organic amine solvent(s). The polymers produced were predominantly insoluble materials with reasonable thermal stability.
Synthesis of acetylene‐terminated polymers using supported palladium (II) catalysts
Authors: Trumbo D. L. , Marvel C. S. 
Published: April 2003

AbstractA polymer‐bound palladium catalyst was synthesized from palladium diacetate and a single crystal polyethylene having 2,2′‐bipyridyl moieties as pendant groups. The resulting material was used in place of a free palladium catalyst in the synthesis of acetylene‐terminated resins. Supports other than polyethylen were also tested for their ability to bind palladium and their subsequent activity as catalysts in the synthesis of acetylene‐terminated polymers.
13C‐NMR study of chlorinated ethylene–vinyl acetate copolymers
Authors: Willman J. R. Schneider , Peat I. R. 
Published: April 2003

Abstract13C‐NMR has been used to analyze the microstructures of a series of experimental chlorinated ethylene–vinyl acetate copolymers (15–56% CI). Previously established line assignments for EVA copolymers and substituent effect parameters for chlorine have enabled us to tentatively assign partial structures up to five carbon atoms in length. The 13C‐NMR analyses of a commercial vinyl chloride–vinyl acetate copolymer, a commercial vinyl chloride–vinyl acetate–ethylene terpolymer, and a commercial chlorinated polyethylene support the structural assignments. Data obtained for the experimental resins indicate that the acetate groups influence the way in which chlorine is added to the polymer chain. furthermore, the data indicate the acetate groups undergo little, if any, chlorination.
Secondary and tertiary oxonium ions in the polymerization of 1,3‐dioxolane initiated with HOSO2 CF3: 1H‐NMR studies
Authors: Kubisa Przemysław 
Published: April 2003

AbstractIn the polymerization of 1,3‐dioxolane (DXL) initiated with trifluoromethanesulfonic acid (TFAc) the proton originated from acid [underlined in the scheme (1)] may form either the hydroxy end‐group or the secondary oxonium ion:

equation image

where is a part of linear or cyclic macromolecule (or monomer). In 1H‐NMR spectra, due to the fast exchange, only one averaged signal of proton is observed, its chemical shift reflecting the relative concentration of both species. The chemical shift of proton, measured at different monomer and initiator concentrations changes, indicating that the proportion of macromolecules bearing OH end‐groups increases with increasing [monomer]o/[initiator]o ratio. This observation is fully consistent with a mechanism, according to which secondary oxonium ions are formed by inter‐or intramolecular reaction between growing species and OH end‐groups of linear macromolecules.
Proton, phosphorus and carbon nuclear magnetic relaxation studies on the interaction of poly(riboadenylic acid) with Cu2+
Authors: Enmanji Koe 
Published: April 2003

AbstractInteraction between poly(riboadenylic acid) (poly(A)) and Cu2+ in neutral aqueous (D2O) solution has been studied by 1H, 31P, and 13C nuclear magnetic resonance. electron‐nuclear hyperfine coupling constant and apparent electron‐nuclear distances were determined by measurement of T1 and T2 values as a function of temperature. The apparent distance from Cu2+ to H(2), H(8), H(1′), and phosphorus nuclei were estimated to be 4.1, 3.7, 5.1, and 3.1 Å from these results. Cu2+ was found to coordinate directly to the phosphate groups of poly(A) (Type I complex). Simultaneously there are bindings of Cu2+ directly to one of the nitrogen atoms of adenine ring, mainly to N(7) (Type II complex) and either N(1) or N(3) (Type III complex).
Assignment of proton NMR spectrum of triglycidylether of para‐aminophenol (TGPAP), using two‐dimensional techniques: SUPERCOSY and J‐resolved
Authors: Jagannathan N. R. , Herring F. G. 
Published: April 2003

AbstractOne‐ and two‐dimensional 400‐MHz proton NMR experiments are reported for the epoxy resin monomer, triglycidylether of para‐aminophenol (TGPAP). Assignment of the epoxy protons becomes difficult due to many overlapping signals from the glycidylamine and glycidylether regions. To solve this problem we employed the homonuclear proton shift‐correlated (SUPERCOSY) and J‐resolved two‐dimensional techniques. The combination of these methods permits the complete elucidation of the complex spectrum.
Preparation of poly(fumaric acid) from poly(di‐t‐butyl fumarate) and poly(di‐trimethylsilyl fumarate)
Authors: Kitano Toshiaki , Ishigaki Akemitsu , Uematsu Gen‐Ichi , Kawaguchi Seigou , Ito Koichi 
Published: April 2003

AbstractPolymerization conditions of di‐t‐butyl fumarate and di‐trimethylsilyl fumarate were studied in detail. They cannot be polymerized by either anionic or coordination initiators, but radical and radiation polymerizations are successful. Characterization of poly(di‐t‐butyl fumarate), obtained thereby, with 1H‐NMR spectrum suggests that the backbone of the chain is stiff. From analysis of thermal properties of poly(di‐t‐butyl fumarate), it is found to be completely converted to poly(fumaric acid) by pyrolysis around 200°C. Poly(di‐trimethylsilyl fumarate), on the other hand, can be quantitatively hydrolyzed with acid to the same polyacid, too. The preliminary measurement of the dissociation behaviors of poly(fumaric acid) was done by potentiometric titration, which shows that the titration curves of poly(fumaric acid) are different from those of poly(acrylic acid) and poly(maleic acid).
Relationship between distribution of substituents and water solubility of O‐methyl cellulose
Authors: Takahashi Shin‐Ichi , Fujimoto Tetsuya , Miyamoto Takeaki , Inagaki Hiroshi 
Published: April 2003

AbstractThe solubility behavior of O‐methyl cellulose (MC) in water was investigated in terms of the distribution of substituents along the cellulose chain as well as in the anhydroglucose (AHG) units. For this purpose, three different types of MC samples were prepared by respective homogeneous reaction, i.e.. (i) methylation of cellulose acetate (CA) prepared from cellulose triacetate (CTA), followed by deacetylation, (ii) methylation of CA prepared by direct acetylation of cellulose in a 10% LiCl–dimethylacetamide (DMAc) solution, followed by deacetylation, and (iii) methylation of cellulose with dimethyl sulfate in a 10% LiCl–DMAc solution. Their water solubility was compared with that of MC samples prepared by the alkali cellulose process, i.e., by the heterogeneous reaction, including commercial products. It was found that water‐soluble MC samples prepared by the alkali cellulose process exhibit a thermally‐reversible sol‐gel transition in aqueous solution, but all of the MC samples preapred homogeneous reactions show a normal phase separation in aqueous solution. This result gives a direct support for the consideration that the highly substituted glucose sequences present in the commercial MC act as “crosslinking loci” on warming. The distribution of substituents in the AHG units was estimated by 13C‐NMR method. The results on the water solubility of MC were also discussed in terms of the distribution of substituents in the AHG units.
Catalysis of copper(II) chelate‐amine complexes in the oxidative coupling of 2,6‐dialkylphenols
Authors: Tsuruya Shigeru , Nakagawa Katsutoshi , Masai Mitsuo 
Published: April 2003

AbstractThe oxidative coupling reaction of 2,6‐dimethylphenol and 2,6‐di‐tert‐butylphenol with molecular oxygen was performed by using a series of copper(II) chelate complexes as a catalyst, derived from copper(II), β‐diketone, and some Shiff bases. Under the applied reaction conditions, the reaction products of 2,6‐dimethylphenol were poly(2,6‐dimethyl‐1,4‐phenylene oxide) (CO coupling product) and 3,3′,5‐5′‐tetramethyl‐4,4′‐diphenoquinone (CC coupling product), and that of 2,6‐di‐tert‐butylphenol oxidation was only 3,3′,5‐5′‐tetra‐tert‐butyl‐4,4′‐diphenoquinone (CC coupling product). The catalytic activity has been shown to be dependent on the properties of the copper(II) chelates used as catalysts and the mole ratios of amine ligand to copper(II) chelate (ligand ratio). The basicity and the steric bulkiness of the amine used as a ligand for copper(II) β‐diketonato catalysts were found to be two of the main factors that govern the oxidative coupling mode (CO and/or CC coupling) of 2,6‐dimethylphenol. The oxidative coupling activity of 2,6‐dialkylphenol is discussed in terms of both the stabilities of the copper(II) chelates and of the copper(II) chelate‐amine adducts. The rate of oxygen absorption for 2,6‐dimethylphenol catalyzed by the copper(II) acetylacetonato‐piperidine system is first order in oxygen partial pressure and zero order in 2,6‐dimethylphenol concentration, respectively. A Cu(II)‐oxygen, as an intermediate is suggested on the basis of the results obtained.
Magnesium chloride supported high mileage catalysts for olefin (decene‐1) polymerization XV. Termination and energetics
Authors: Chien James C. W. , Ang Tsunle 
Published: April 2003

AbstractPolymerizations of decene‐1 were carried out from 0° to 70° at A/T = 167 and [M] = 0.75 M initiated by 0.17, 0.34, and 0.69 mM of Ti contained in the MgCl2/ethylbenzoate/p‐cresol/AlEt3/TiCl4‐AlEt3/methyl‐p‐toluate catalyst. The rate of polymerization is directly proportional to the catalyst concentration. About 12% of the Ti in the catalyst is initially active at 50°; they are 1.4%, 8.8%, and 9.4% at 0°, 25°, and 70°, respectively. The changes of Rp with temperature parallels the variations in the active site concentration. The decline of Rp with time has second‐order plots with slopes which are inversely proportional to the catalyst concentration, but the rate constants for these deactivations are nearly the same for decene and propylene polymerizations. These results strongly support a mechanism of deactivation involving two adjacent sites in the catalyst particle surfaces. The rate constants of propagation and of chain transfer to AlEt3, the energetics for these processes, and MW and MW distribution data have been obtained.
Photoelectrochemistry in particulate systems. 5. Visible light‐induced polymerization of 1‐vinylpyrene in semiconductor suspensions
Authors: Kamat Prashant V. , Todesco R. V. 
Published: April 2003

AbstractPhotoelectrochemical polymerization of 1‐vinylpyrene has been achieved in a semiconductor photocatalyst suspension under visible light irradiation (λ > 480 nm). Bandgap excitation of CdS, CdSe or Fe2O3 led to the oxidation of 1‐vinylpyrene, which initiated the polymerization process. A 25–47% yield of poly(1‐vinylpyrene) could be obtained upon irradiation of these semiconductor photocatalyst suspensions with 1‐vinylpyrene in acetonitrile. Dependence of the polymer yield on various experimental conditions is described.
ESCA and optical emission study of the inductively coupled RF plasma copolymerization of naphthalene and octafluoronaphthalene mixtures
Authors: Munro H. S. , Till C. 
Published: April 2003

AbstractPlasma polymerization of octafluoronaphthalene, naphthalene, and 1 : 1 mixtures of the two yielded thin films which were then analyzed by ESCA. Optical emission was recorded during deposition and the resultant spectra are shown. Deposition of the copolymer at 150°C resulted in a film whose composition was different from that deposited at room temperature and from the single plasma polymers. Copolymerization resulted in a lowering of CF2 functionalities and an increased retention of the aromatic nature of the monomers. Optical emission of CF2 during copolymerization was greatly reduced as was a peak at about 510 nm.
Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. I. p‐isopropenylphenyl glycidyl ether: An epoxy‐functionalized α‐methylstyrene
Authors: Hashimoto Tamotsu , Sawamoto Mitsuo , Higashimura Toshinobu , Saito Noriaki 
Published: April 2003

Abstractp‐Isopropenylphenyl glycidyl ether (IPGE), a monomer of dual cationic functionality (isopropenyl and epoxy), was polymerized by a variety of initiators, and optimum conditions were established for its selective vinyl cationic polymerization. The hydrogen iodide/iodine (HI/I2) initiating system or iodine polymerized selectively the isopropenyl group in CH2Cl2 at a low temperature (−78°C), to produce soluble poly(IPGE) with epoxy pendants. Under these conditions, the number‐average molecular weight of the polymers was inversely proportional to the initial initiator concentration, indicating the formation of long‐lived propagating species. Soluble poly(IPGE) was also obtained at −15 and −40°C by HI/I2 or iodine. However, at these higher temperatures, transfer and/or termination reactions took place to give olefin‐terminated polymers, in which some of the pendant epoxy groups were consumed. BF3OEt2 (a metal halide) and CF3SO3H (a strong protonic acid) polymerized both epoxy and isopropenyl groups of IPGE and yielded crosslinked insoluble polymers.
Polyimides containing carbonyl and ether connecting groups
Authors: Hergenrother P. M. , Wakelyn N. T. , Havens S. J. 
Published: April 2003

AbstractGeveral new polyimides were prepared from the reaction of four aromatic dianhydrides with four new diamines containing carbonyl and ether connecting groups between the aromatic rings. The diamines were prepared from the reaction of 4‐aminophenol with activated aromatic difluoro compounds in the presence of potassium carbonate. Several of these polyimides were shown to be semicrystalline as evidenced by wide angle x‐ray diffraction and differential scanning calorimetry. Glass transition temperatures ranged between 192 and 247°C and crystalline melt temperatures were observed between 350 and 442°C. The polyimide from the reaction of 3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride and 1,3‐bis(4‐aminophenoxy‐4′‐benzoyl)benzene provided a semicrystalline solvent resistant transparent film with high tensile properties and compression molded compact tension specimens with high fracture toughness.
Inverse emulsion polymerization of acrylamide. II. Synthesis and characterization of copolymers with methacrylic acid
Authors: Glukhikh V. , Graillat C. , Pichot C. 
Published: April 2003

AbstractInverse emulsion copolymerization studies of acrylamide (Am) with methacrylic acid (MAA) are reported. Aqueous monomer solutions were emulsified in toluene with a blend of two surfactants (sorbitan sesquioleate and C18‐terminated acrylamide oligomers). Polymerization kinetics in presence of an oil‐soluble initiator (AIBN) were determined at 40°C as a function of methacrylic acid content and aqueous‐phase pH. Polymerization rates were found to be faster at basic pH than at acidic pH, which appeared to be related to the actual concentration of methacrylic acid in the aqueous phase. Monomer reactivity ratios have been derived as rA‐M = 0.58 ± 0.02 and rM‐A = 4.0 ± 0.10 at pH 4, rA‐M = 0.56 ± 0.005 and rM‐A = 0.15 ± 0.03 at pH 10. These differences were found to have an effect on the molecular characteristics of the copolymers. Initial emulsions and final inverse latexes displayed the same broad size distribution; under basic pH the particle size is relatively insensitive to the ionic comonomer concentration. Poor latex stability is characteristic of copolymer latexes prepared under acidic conditions. Based on these experimental results, some aspects of the polymerization mechanism are discussed.
Morphology and grafting reactions in core/shell latexes
Authors: Merkel M. P. , Dimonie V. L. , El‐Aasser M. S. , Vanderhoff J. W. 
Published: April 2003

AbstractThe particle morphology and percent grafting were investigated as a function of the crosslink density of the seed latex in two systems of core/shell latexes of polybutadiene/polymethyl methacrylate (PB/PMMA) and styrene–butadiene rubber/polymethyl methacrylate (SBR/PMMA) prepared by seeded emulsion polymerization at 50°C. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to characterize the grafting efficiency of the core/shell latexes. The percent grafting of the shell polymer was found to decrease with increasing the crosslink density of the core material. The particle morphology and precent grafting were also investigated as a function of composition and structure of the core material in four core/shell latex systems: polybutadiene/styrene–acrylonitrile copolymer (PB/SAN), (styrene‐butadiene) random copolymer/styrene acrylonitrile copolymer (S:B/SAN), polystyrene : polybutadiene/styrene‐acrylonitrile copolymer (PS:PB/SAN) and Kraton/styrene‐acrylonitrile copolymer (Kraton/SAN), which were prepared by direct emulsification for the seed followed by emulsion polymerization at 70°C for the shell polymer. Grafting and crosslinking of the core material were found to be competitive reactions depending on the microstructure of the seed latex.
Product analyses and crosslink mechanism of plasma‐polymerized methyl methacrylate
Authors: Ohno Mikio , Ohno Keiichi , Sohma Junkichi 
Published: April 2003

AbstractPlasma‐polymerized methyl methacrylate (PPMMA) film was produced by a radio‐frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol‐PPMMA) and an insoluble matrix (insol‐PPMMA), which is highly crosslinked, by solvent‐extraction and filtration. The chemical structure of the sol‐PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, 1H‐NMR, 13C‐NMR, and elemental analysis techniques. On the other hand, the structure of the insol‐PPMMA was examined with IR spectroscopy, 13C‐NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol‐PPMMA and the insol‐PPMMA.
Structural changes in glassy polymers studied by thermal analysis and dynamic mechanical tests
Authors: Spathis G. , Kontou E. , Theocaris P. S. 
Published: April 2003

AbstractStructural changes which take place in many amorphous polymers, when they are annealed at temperatures near the glass transition temperature, have important theoretical, physical, and mechanical consequences. In this paper the possible existence of some local ordering in highlycrosslinked epoxy resins is studied. Three kinds of tests—TMA, DSC, and dynamic experiments—are used for a type of epoxy resin, cured with six different amounts of curing agent. In order to study the effect of the thermal history on the behavior of the polymer at its transition region, as well as the morphology of the materials tested, three different thermal treatments have been followed. Interesting results were derived concerning the influence of these parameters to these parameters to the mechanical characterization of the polymer.