bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spontaneous copolymerization of 4‐methylene‐1,3‐dioxolanes with maleic anhydride
Authors: Fukuda Hiroyuki , Hirota Masahiro , Nakashima Yoshihiro 
Published: April 2003

AbstractThe copolymerization of methylenedioxolanes, such as 4‐methylene‐1,3‐dioxolane (I) and 2,2‐dimethyl‐4‐methylene‐1,3‐dioxolane (II), with maleic anhydride (Manh) gives rise spontaneously to the alternating copolymers by the participation of charge‐transfer (CT) complexes. The formation of CT complexes I‐Manh and II‐Manh was ascertained by UV and NMR spectroscopies. The equilibrium constants (K) could not be determined but were assumed to be small (K ≪ 1). For comparison with these systems an investigation of I‐dimethyl maleate (DMM) and II‐DMM systems was carried out to estimate K values 0.115 and 0.157 L/mol, respectively. To clarify the copolymerization mechanism I‐Manh‐acryronitrile was terpolymerized. Consequently it was concluded that the spontaneous copolymerization of I‐Manh and II‐Manh systems is effected by the CT complex monomer mechanism.
Synthesis of azido‐polymers of butadiene
Authors: Lillya C. Peter , Juang Rong‐Hwei , Chien James C. W. , Miller R. S. 
Published: April 2003

AbstractIodine azide adds to cyclohexene in acetonitrile or 4:1 methylene chloride/acetonitrile to give trans‐1‐azido‐2‐iodocyclohexane. In methylene chloride this reaction gives a mixture of the cis‐and trans‐iodoazides owing to competing radical addition. Iodine azide adds to 1‐hexene in acetonitrile by an ionic mechanism to give a 3:1 mixture of the 2‐azido‐1‐azido‐ and 1‐azido‐2‐iodohexanes. Dehydroiodination of the model iodoazides proceeds smoothly with potassium t‐butoxide in diethyl ether or THF in the presence of 5 mol % 18‐crown‐6 at room temperature, giving in the previous example a mixture of 2‐azido‐ and trans‐1‐azidohexenes. Polybutadiene, carboxyterminated poly(acrylonitrile‐co‐butadiene), and hydroxy‐terminated polybutadiene gave iodoazide derivatives with up to 96% of the theoretical maximum nitrogen content and strong azide IR absorption. High azidoiodination gave polymer with N3/I ratios slightly higher than unity while low percent azidoiodination led to polymer with N3/I ratios of as low as 2:3. All of the nitrogen introduced was in the form of azide function. Dehydroiodination gave polymers with vinyl azide functionality and caused loss of some of the azide groups. All the azidoiodinated polymers decomposed between 120 and 160°C. The dehydroiodinated materials were less stable, decomposing between 100 and 150°C. The temperature of initial decomposition decreased as azide content increased. Polymers with >55–60% of the theoretical maximum azide content were shock sensitive.
Copolymerization of isobutene and α‐methylstyrene as a function of reaction conditions
Authors: Wondraczek Reinhard H. , Müller Winfried , Schütz Heidrun , Heublein Günther 
Published: April 2003

AbstractThe influence of reaction conditions (solvent, Lewis acid, temperature) on the cationic copolymerization of isobutene and α‐methylstyrene was investigated. The crude product consists of low molecular nonprecipitable oligomers, polyisobutene, and poly(isobutene‐co‐α‐methylstyrene). The amount of poly(α‐methylstyrene) formed under the reaction conditions used was negligible. The degree of charge separation in the propagating cationic intermediate determines the selectivity of the reaction; that is, incorporation of monomer units into the polymer, ratio of different product fractions, and microstructure. Molecular weight distribution, copolymerization parameters, and sequence‐length distribution functions were determined. The softening range of the copolymers depended on their isobutene content but appeared to be constant up to 15% isobutene in copolymers. The degradation temperature of the copolymers was between 340 and 390°C.
Piezoelectric polymer films. I. Synthesis and properties
Authors: Liepins R. , Timmons M. L. , Morosoff N. , Surles J. 
Published: April 2003

AbstractThe synthesis of a new class of piezoelectrically active materials comprised of various co‐ and ter‐polymers of tributyltin methacrylate (TBTM) and trimethyltin methacrylate (TMTM) are described. In this article films of the various polymer compositions were evaluated for tin content, glass transition temperature (Tg), and crystallinity or “ordering” of the amorphous phase. A brief theory of piezoelectricity in polymers will be given in Part II with a description of sample preparation, poling techniques, and the measurement system, as well as piezoelectric evaluation results.
Investigations of stabilizing additives. I. A model system for studying radical scavenging activity in solution
Authors: Dunn T. S. , Williams E. E. , Williams J. L. 
Published: April 2003

AbstractIn the current study an electron spin resonance model system was developed to compare the thermal stability and radical scavenging activity of stabilizers in solution. High‐resolution spectra and the influence of molecular structure on radical stability provided a basis for the interpretation of spin concentration data in the model system. A correlation was established between the radical scavenging activity measured in the model system and actual behavior in irradiated polypropylene formulations measured by radiation‐induced degradation of mechanical properties.
Studies on stable free radicals. XIX. Copolymerization of N‐oxyl biradical with α‐chloro‐p‐xylylene
Authors: Fujita Takashi , Yoshioka Takao 
Published: April 2003

AbstractCopolymerization of N‐oxyl biradical with α‐chloro‐p‐xylylene was carried out by varying the feed ratio of α,α′‐dichloro‐p‐xylene which was the precursor of α‐chloro‐p‐xylylene. The structures of the obtained copolymers were determined spectroscopically. The results that the N‐oxyl attacked the carbon‐bearing chlorine atom of α‐chloro‐p‐xylylene suggest a nucleophilic reactivity of N‐oxyl radical. The copolymerization process was also discussed.
Mass spectral characterization of polymers. Primary thermal fragmentation processes in polyureas
Authors: Caruso S. , Foti S. , Maravigna P. , Montaudo G. 
Published: April 2003

AbstractThe primary fragmentation processes in the thermal decomposition of polymers were studied in detail on a series of structurally related polyureas by direct pyrolysis with a mass spectrometer. Our results indicate that polyureas I–III undergo a quantitative depolycondensation process analogous to that observed for N‐monosubstituted polyurethanes. The thermal decomposition of polyureas IV–VI proceeds by intramolecular hydrogen transfer processes that occur at higher temperatures with respect to depolycondensation. Polycarboxypiperazine VI is decomposed by a single‐stage decomposition mechanism that leads to fragments with amino end groups and carbon oxide.
Effects of triphenylsulfonium hexafluorophosphate in the radiation‐induced cationic polymerization of styrene
Authors: Mah Soukil , Yamamoto Yukio , Hayashi Koichiro 
Published: April 2003

AbstractRadiation‐induced cationic polymerization of styrene was studied in methylene chloride in the presence of triphenylsulfonium hexafluorophosphate. Acceleration in polymerization and an increase in molecular weight at a low temperature (−78°C) were observed in the presence of triphenylsulfonium salt. A study of pulse radiolysis revealed that both effects are due mainly to PF−6, which forms ion pairs with the cationic species involved in the polymerization.
Plasma polymerization. VII. An esca investigation of the RF plasma polymerization of perfluorobenzene and perfluorobenzene/hydrogen mixtures
Authors: Clark D. T. , Abrahman M. Z. 
Published: April 2003

AbstractThe composition and gross structural features of plasma polymers formed in the glow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorobenzene/hydrogen mixtures were investigated by ESCA as a function of the operating parameters. The carbon‐to‐fluorine stoichiometries of the perfluorobenzene polymers are similar and close to those of the starting material but not of the polymers derived from perfluorobenzene/hydrogen mixtures. The rate of film deposition is dependent on the W/FM parameter. Angular and photon energy‐dependent studies confirm the vertical homogeneity of the plasma polymer films investigated.
Calculation of Alfrey–Price Q–e Values from 13C‐NMR Data
Authors: Borchardt John K. , Dalrymple E. Dwyann 
Published: April 2003

AbstractA multiple‐correlation analysis program was used to generate equations relating the Alfrey–Price Q and e values of vinyl monomers to the 13C‐NMR absorption frequencies of the α‐ and β‐carbon atoms of the monomers. Separate equations for the calculation of Q and e values of styrenes, chlorinated olefins, acrylates, methacrylates, vinyl ethers, and esters, nitrogen containing monomers, allyl compounds, and miscellaneous olefins were developed. The correlation coefficients of most of these equations were greater than 0.99 and permit accurate calculation of the Q and e values. The Q and e values so calculated may then be used to obtain estimates of the reactivity ratios in copolymerizations prior to actually performing the experiments. Attempts to develop a single Q value equation and a single e value equation for 63 vinyl monomers of the above classes resulted in relations having correlation coefficients of 0.63 and 0.81, respectively, too low to permit sufficiently accurate calculation of the Q and e values.
An ESCA study of the surface ozonation of polystyrene film
Authors: Peeling James , Jazzar Mohammad S. , Clark David T. 
Published: April 2003

AbstractPolystyrene film was treated with 0.27 mol % ozone in oxygen at room temperature. Changes in the surface were monitored by ESCA. Reaction occurred uniformly in at least the outermost 60 Å of the film. Reaction was rapid, giving a surface composition that corresponded to C1.8O after about 8 h, with no apparent yellowing or embrittlement of the polymer. Ether, ketone, and carboxyl groups were formed at uniform, but not equal, rates in the outer 60 Å of the polymer. With short reaction times the less highly oxidized groups were the main oxidation product, but after about 4 h the highly oxidized groups predominated. The aromatic rings underwent reaction as indicated by the rapid disappearance of the C1s shake‐up satellites on ozonation.
Alternating copolymerization of N‐benzylidine aniline (NBA) with α‐haloacrylic acids (XAA). IV. Synthesis, characterization, and kinetics
Authors: Balakrishnan Thayikkannu , Periyasamy Mookkan 
Published: April 2003

AbstractThis article describes a new, spontaneous, 1:1 alternating copolymerization between a Schiff base, N‐benzylidine aniline (NBA), and α‐haloacrylic acids (XAA) such as α‐chloroacrylic acid (ClAA) and α‐bromoacrylic acid (BrAA). The structure of the copolymers was identified by nuclear magnetic resonance (NMR) and infrared (IR) spectra. By using the isolation method we determined the order of each monomer. On the basis of kinetic studies, a mechanism that involves initiation, propagation, and termination by zwitterion is proposed. The effects of copolymerization under various conditions were studied and the intrinsic viscosity and number‐average molecular weight were measured. The overall energy of activation, ERp, for the copolymerization was determined and thermal degradation studies were made.
Complex formation of amphiphilic polymers with azo dyes and their photoviscosity behavior
Authors: Negishi Naoki , Ishihara Kazuhiko , Shinohara Isao 
Published: April 2003

AbstractThe hydrophobic interaction of amphiphilic copolymers, which contain 2‐hydroxyethyl methacrylate(HEMA) and 1vinyl‐2‐pyrrolidone (VPy), with Methyl Orange (MO) was compared with that of HEMA‐acrylamide (AAm) copolymers to deduce the correlation between their complexation ability in a photochromic azo dye and the photoviscosity effect in aqueous copolymer/dye complex solution. On the basis of the dialysis data and fluorometric analysis it appeared that the complexation dependence on HEMA content in the copolymers was due to the hydrophobic interaction between the polymer and the dye. For a comparable HEMA content AAm copolymers bound less MO than VPy copolymers. It was confiied by photoviscosity measurements that the conformation of the complex composed of photochromic azo dye and HEMA copolymer changed reversibly in response to the photo‐ and thermal isomerization of the dye. In HEMA‐AAm copolymer systems the photoviscosity effect was small compared with that of HEMA‐VPy copolymer systems. From these results it was concluded that the complexation ability of polymers due to the hydrophobic interaction was an important factor in producing a large photoinduced conformational change in water.
Phthalocyanine polymers. III. Poly(nickel phthalocyanine)benzimidazole as a novel high‐temperature‐resistant polymer
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractA new type of poly(nickel phthalocyanine)benzimidazole was prepared by the condensation reaction between nickel (11) 4,4′,4″,4″′‐phthalocyanine tetracarboxylic acid dihydrate and 3, 3′‐diaminobenzidine. The reaction was investigated by both the melt and solution condensation methods. This polymer showed good thermal and thermo‐oxidative stability. Also noteworthy is its high thermal stability with a char yield of 88% at 800°C in nitrogen. No catastrophic decomposition was observed up to 1100°C. A qualitative study of decomposition in both air and nitrogen is presented. Elemental analyses agreed well with the proposed structure. Infrared (IR) and thermogravimetric analysis (TGA) studies were performed to characterize this polymer, and isothermal gravimetric analysis was done to determine its long‐term thermal stability. The apparent activation energies for the thermal degradation in air and nitrogen are given.
Vinyl polymerization. 410. Polymerizations of vinyl monomers initiated by poly(styrene‐co‐sodium acrylate) or poly(methyl methacrylate‐co‐sodium methacrylate). A verification of the concept of hard and soft hydrophobic areas and monomers
Authors: Ouchi Tatsuro , Inaba Masaya , Tadano Kohei , Imoto Minoru 
Published: April 2003

AbstractIt was found that the copolymers of sodium acrylate (AA‐Na) with styrene (St) and of sodium methacrylate (MAA‐Na) with methyl methacrylate (MMA) could polymerize vinyl monomers in an aqueous phase without the usual initiator. Interestingly, there was a definite composition of the copolymer for the polymerization of a given monomer; for example, when poly(St‐co‐AA‐Na) was used, St, MMA, vinyl acetate, ethyl acrylate, methyl acrylate, and acrylonitrile were polymerized by the copolymer having mole ratios of AA‐Na:St of 0.61:0.29, 0.47:0.53, 0.38:0.62, 0.30:0.70, 0.24:0.76, and 1.00:0, respectively. The copolymers of various compositions can form hydrophobic areas (HAs) in the water phase. As has been repeatedly reported, the polymerization proceeds in the HAs, and the following new hypothesis was recently proposed that the hard (the less hydrophilic) HA prefers to incorporate the hard monomer and the soft (the less hydrophobic or the more hydrophilic) HA prefers to incorporate the soft monomer. The results mentioned above support this hypothesis.
The base‐catalyzed transformation of polyacrylonitrile
Authors: Endrey A. L. 
Published: April 2003

AbstractIn an effort to produce high‐molecular‐weight, linear ladder polymer by linking the nitrile groups within the molecule of polyacrylonitrile, polyacrylonitrile homopolymers were heat treated in N,N‐dimethylformamide and N,N‐dimethylacetamide solutions, in the presence of tertiary alkylamine catalysts. The products were soluble in formic acid, had relatively low molecular weight, and could be cast into brittle films. The infrared spectra indicated that the polymerization of the nitrile groups is initiated by a self‐initiation mechanism based on the active methine groups in polyacrylonitrile, as proposed by Grassie and Hay, and that the reaction is complicated by molecular weight degradation via reverse Michael addition, as proposed by Hamada and Takahashi. The inherent viscosities of the products increase with increasing catalyst concentration, and further increases can be achieved by the addition of anionic chain coinitiators of phenolic nature. Density measurements indicated that the ladder structures undergo rearrangement into a more stereoregular form after formation, and that some aromatization occurs when the reaction is carried out in the presence of air.
Evolution of HCN during high‐temperature thermal degradation of polyurethanes
Authors: Jellinek H. H. G. , Dunkle S. R. 
Published: April 2003

AbstractThe thermal degradation of an aliphatic, aromatic, and secondary polyurethane has been studied over a range of temperatures from 500 to 1000°C with respect to the kinetics and mechanism of HCN evolution. This evolution shows a rapid linear increase of evolved HCN with time, passing into a plateau when the polymer has been consumed. In high temperature ranges, thermal decomposition of the evolved HCN also takes place, and in some temperature regions the degradation is diffusion controlled. Overall, the process is governed by a depolycondensation reaction which is the slowest step in a sequence of reactions. The reaction sequence is kinetically evaluated and the respective rate constants, diffusion constants, and energies of activation are presented. The reaction mechanism accounts well for the experimental results in spite of some simplifications which had necessarily to be applied.
Head‐to‐head vinyl polymers. VII. Hydrolysis of head‐to‐head poly(methyl acrylate)
Authors: Quach Loc , Otsu Takayuki 
Published: April 2003

AbstractHead‐to‐head (H–H) and head‐to‐tail (H–T) poly(methyl acrylate)s (PMAs) were hydrolyzed in a mixture of acetone and water (4:1 by volume) at 30°C by using various alkali hydroxides as catalysts. For comparison, the H–T copolymer with 26% H–H units, dimethyl succinate (DMS), dimethyl glutarate (DMG), and dimethyl adipate (DMA) as model compounds were also hydrolyzed. It was found that the hydrolyses of all PMAs proceeded autocatalytically; i.e., the rates increased as a function of the reaction time. Both the initial rate constant k0 and the autoaccelerating effect observed markedly depended on the structures of polymer chains and they decreased with increasing of the H–H sequences. The molecular weights of either H—H or H—T PMA did not show remarkable changes in either k0 value or accelerating effect. The k0 values were almost independent of the kinds of bases and were calculated to be 0.06 and 0.18 L mol−1 min−1 for H–H and H–T PMA, respectively. On the other hand, the autoaccelerating effect decreased in the order NaOH ⋍ KOH > LiOH > CsOH for H–H PMA and NaOH > LiOH > KOH > CsOH for H–T polymer. When the ratio of acetone to water increased, the k0 value was found to decrease, whereas the accelerating effect increased. The results obtained are described and discussed.
Stereocontrol in the cationic polymerization of N‐vinylcarbazole
Authors: Terrell David R. , Evers Fritjof 
Published: April 2003

AbstractThe dependence of the steric microstructure of cationically polymerized poly(N‐vinylcarbazole) (PVK) upon catalyst, polymerization temperature, and polymerization solvent has been investigated. The effect of polymerization temperature variation was found to be small, whereas the choice of catalyst and polymerization solvent was found to have a strong influence upon the PVK steric microstructure. A correlation was found between the syndiotacticities Xs and the π* solvent polarities of the polymerization solvents for a given catalyst. A decrease in Xs with increasing π* solvent polarity was observed using BF3OEt2 and AlEt2Cl catalysts and has been interpreted in terms of propagation via contact ion‐pair ring structures reversibly formed between the active end group and a preceding repeating unit. The increase in Xs with increasing π* solvent polarity observed with several of the catalysts investigated has been interpreted in terms of chain ion pairs whose separation increases with increasing π* solvent polarity. The influence of the various Lewis acid catalysts upon the steric microstructures of cationically polymerized PVK allowed the following order of nucleophilicity to be established:
Reaction rate of crosslinkings by using metallated polymer. I. Grafting and intramolecular crosslinkings at the first stage
Authors: Ishizu Koji , Ino Kazuhide , Koshiro Yoshitaka , Fukutomi Takashi , Kakurai Toshio 
Published: April 2003

AbstractLithium‐metallated styrene–p‐benzylstyrene copolymer was reacted with chlorine‐terminated polystyrene as a crosslinker polymer in tetrahydrofuran (THF) at 25°C. The rate constant was estimated from the changes in the concentration of metallated polymer by using photometrical measurements. The various reaction conditions were chosen and it became clear that the rate constants of grafting (k1) and intramolecular crosslinkings (k2intra) were gotten separately at the first stage. As a result, k2intra showed larger values than k1 and decreased with increasing degree of polymerization of crosslinker polymers.
Metal‐acetylacetonate chelate crosslinked gels
Authors: Yeh Horng Chin , Eichinger B. E. , Andersen N. H. 
Published: April 2003

AbstractPolymers containing pendant acetylacetonate (acac) groups suitable for crosslinking through metal complex formation are described. Diene‐based copolymers, polystyrene, and polydimethylsiloxane, each containing a measurable number of acac groups distributed along the chains, were synthesized. The polymers were studied both for the amount of acac ligand and for their crosslinking reactions with selected transition metals by ultraviolet (UV) second‐derivative spectroscopy. The UV analyses of the polymer systems were compared with their monomer analogs, and the results confirm that the crosslinking chelation reactions of polymer compounds are similar to those of model compounds. Homogeneous chelate crosslinking conditions were developed by using transition‐metal salts such as Cu(laurate)2, Fe(laurate)3, and Cr(laurate)3 in solvents such as chloroform and benzene. Polymeric ligands containing 1–5% acac in solution at various concentrations were reacted to form both inter‐ and intramolecular crosslinkages. The kinetic stability of the chelate crosslinks has been studied by a unique ligand exchange–gel solubility relationship.
Polymerization of phenylacetylene by WCl6·Ph4Sn: Synthesis of high polymer achieved by selection of solvents
Authors: Masuda Toshio , Takahashi Toru , Yamamoto Kaoru , Higashimura Toshinobu 
Published: April 2003

AbstractPhenylacetylene was polymerized by WCl6·Ph4Sn (1:1) in 1,4‐dioxane to provide in high yield a polymer whose molecular weight reached 1 × 105. The polymerization also proceeded in other oxygen‐containing solvents (ethers, esters, and ketones) but the polymer molecular weights were lower than 1 × 104. Certain hydrocarbon solvents such as cyclohexene, tetralin, and indan also afforded high‐molecular‐weight polyphenylacetylene [Mn = (5–8) × 104], as compared with those (Mn ≤ 1.5 × 104) obtained in conventional aromatic hydrocarbons like benzene. A high polymer (Mn = 1.6 × 105) was also formed from β‐naphthylacetylene in 1,4‐dioxane. It was inferred that the active hydrogens of these solvents prevent the formed polymer from being decomposed by a radical mechanism and/or modify the nature of active species.