bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidized polyethylenimine
Authors: Haas Howard C. , Schuler Norman W. , Macdonald Ruby L. 
Published: April 2003

AbstractPolyethylenimine (PEI) has been oxidized with aqueous hydrogen peroxide to yield a hygroscopic, water‐soluble, slightly basic, yellow polymeric solid (OPEI) containing about 25% oxygen. Some chain degradation accompanies oxidation. The nature of the product varies somewhat with preparative conditions. OPEI, in the presence of strong alkali, reduces silver salts and peptizes a portion of the silver. By use of infrared, ultraviolet, and proton magnetic resonance spectroscopy together with qualitative testing, OPEI has been found to contain carboxyl groups, unoxidized primary amine groups, tertiary amine oxide, small amounts of aldehyde and nitrone groups, and a considerable amount of secondary amide. The probable reaction sequence is: PEI → dialkylhydroxylamine → nitrone → oxazirane → rearranged product. Oxazirane groups appear to be absent, as well as oxime, nitro, nitrite, and nitrate. The groups which reduce silver salts are not known with certainty but are probably of the hydroxylamine type. The carboxyl content of OPEI is associated with the lower molecular weight species which are present.
Effect of the excluded volume on specific rate of combination reactions between polymer radicals
Authors: Ito Katsukiyo 
Published: April 2003

AbstractThe specific rate kD for reaction between polymer radicals is formulated when the potential of average force on the basis of the excluded volume affects the motion of the polymer radicals. This rate is given by \documentclass{article}\pagestyle{empty}\begin{document}$ k_D = Fk_S \left( {{\rm with}\ {F} = \sum\limits_{s = 0}^\infty {{{[ &#x02010; 2(\alpha ^2 &#x02010; 1)]} \mathord{\left/ {\vphantom {{[ &#x02010; 2(\alpha ^2 &#x02010; 1)]} {(s + 1)^{{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern&#x02010;\nulldelimiterspace} 2}} }}} \right. \kern&#x02010;\nulldelimiterspace} {(s + 1)^{{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern&#x02010;\nulldelimiterspace} 2}} }}} } \right) $\end{document} where kS is specific rate of reaction between radical chain ends and α is the average expansion of the polymer arising from the long‐range effects. The effect of the excluded volume reduces kD. F depends on the degree of polymerization of the polymer radical when α ≠ 1. These results are discussed in terms of the experimental data for very low polymer concentrations.
Sulfur‐containing polymers. V. Preparation of polyoxycarbonylsulfenamides by polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines
Authors: Kobayashi Norio , Fujisawa Tamotsu 
Published: April 2003

AbstractPolyoxycarbonylsulfenamides (POSA) have been prepared by interfacial polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines. The polymers obtained ranged in physical form from crystalline solids to resinous materials depending on the kind of both bis(oxycarbonylsulfenyl chlorides) and diamines used. Some of the polymers gave transparent pliable films from chloroform solution. The polymer films decomposed with liberation of carbonyl sulfide on being subjected to ultraviolet radiation.
Benzophenone/triethylamine‐photoinitiated polymerization of methyl acrylate
Authors: Sandner M. R. , Osborn C. L. , Trecker D. J. 
Published: April 2003

AbstractBenzophenone‐sensitized photopolymerization of methyl acrylate was shown to be remarkably enhanced by the addition of small amounts of triethylamine. This was attributed to the efficient formation of an electron‐transfer complex between photoactivated benzophenone and ground‐state amine. Ketyl and amine free radicals derived from this complex were postulated to be the chain‐initiating species. Quantum yield experiments indicated that methyl acrylate itself was also a quencher of the benzophenone triplet state.
Polymerization of α‐methylstyrene by n‐butyllithium in tetrahydrofuran
Authors: Bitsenko M. I. , Podolsky A. F. , Khvostik G. M. , Sokolov V. N. 
Published: April 2003

AbstractThe kinetics of polymerization of α‐methylstyrene by n‐BuLi (labeled with C14 and unlabeled) has been studied in tetrahydrofuran at −78°C. The catalyst n‐BuLi was used as a complex of n‐BuLi in THF and a hexane solution of n‐BuLi. Contrary to expectations, the relative polymerization rate and the catalyst consumption were higher when a hexane solution of n‐BuLi was used. Experimental molecular weights of the polymers greatly exceeded those calculated for the case of complete catalyst consumption. The polymers exhibited low polydispersity, and when a hexane solution of n‐BuLi was used, the molecular weight distribution was bimodal. The rate of initiation for the case of polymerization α‐methylstyrene with a hexane solution of n‐BuLi as a catalyst was much higher than in the polymerization of α‐methylstyrene with the use of the complex of n‐BuLi in THF as in situ catalyst. Experimental data confirm the preferable interaction of α‐methylstyrene with associated n‐BuLi in the presence of THF. The complex which was formed as a result of such interaction is an active centers of polymerization.
Photoinduced ionic polymerization. II. Cationic polymerization of α‐methylstyrene in the presence of tetracyanobenzene
Authors: Irie Masahiro , Tomimoto Setsuko , Hayashi Koichiro 
Published: April 2003

AbstractThe dependence of the rate of polymerization on light intensity and the stereoregularity of the polymer was studied to elucidate the propagation and termination mechanisms of the photoinduced cationic polymerization of α‐methylstyrene in the presence of tetracyanobenzene in methylene chloride. The rate of polymerization was proportional to the light intensity. The polymer is highly syndiotactic, and the stereoregularity is similar to that of polymers obtained by radiation‐induced cationic polymerization. The initiation mechanism was also studied by electron spin resonance, by which the anion radical of tetracyanobenzene formed from a photoexcited complex between α‐methylstyrene and tetracyanobenzene was observed. The cation radical of α‐methylstyrene, counterpart of the anion radical, is believed to initiate the polymerization.
Copolymerization of styrene and diethyl fumarate with ZnBr2. IV. Comparison between photoinitiation and electroinitiation
Authors: Davies D. H. , Phillips D. C. , Smith J. D. B. 
Published: April 2003

AbstractA comparative analysis of photoinitiation and electroinitiation can help elucidate initiation processes in donor‐acceptor charge‐transfer copolymerization. The technique has been applied to the zinc bromide‐catalyzed copolymerization of styrene and diethyl fumarate in methanol. The photocopolymer product was analyzed by GPC, NMR, and elemental analysis. The results showed that 1:1 copolymers were formed initially, but changes occurred in both the kinetics and products after the early stages of the reaction. Significant correlations found between the two initiation methods included the initial kinetic order with respect to the initiating process and the effect on product yield of equivalent increases in total initiation energy. The limiting value of zinc bromide for both initiation methods was found to be the same. The data obtained support the contention that the copolymerization proceeds through a donor–acceptor process and that photoactivation of the preformed complex, inducing electron transfer, is a likely initiation process.
Copolymerization of styrene and diethyl fumarate with zinc bromide. III. Electroinitiation at low current densities
Authors: Phillips D. C. , Smith J. D. B. , Davies D. H. 
Published: April 2003

AbstractThe electroinitiated preparation of equimolar copolymers of styrene and diethyl fumarate is described. The reaction medium consisted of these monomers dissolved in a methanol–zinc bromide solution. Rates of polymerization increased with increasing applied current and the copolymer yield increased linearly with the total number of Faradays transferred. The copolymer composition is 1:1 and is essentially invariant with the degree of conversion (<15%), electroinitiation rate, and monomer feed ratios. A reaction mechanism involving donor–acceptor complexes and electroinitiated excitation of these complexes at the electrode is postulated.
Polypropylene oxidation kinetics
Authors: Goldfarb Louis , Foltz Carl R. , Messersmith David C. 
Published: April 2003

AbstractDifferential thermal analysis methods have been used to investigate the kinetics of oxidation of isotactic polypropylene. The interpretation of results is based on an oxidation mechanism that emphasizes the role of hydroperoxide production. The mechanism has been simulated by computer methods, and the rate constants for the abstraction of labile hydrogen atoms as well as an apparent energy of activation are obtained.
Preparation and polymerization of 3‐acrylamido‐3‐methylbutanoic acid
Authors: Hoke Donald I. , Robins Richard D. 
Published: April 2003

AbstractThe preparation of 3‐acrylamido‐3‐methylbutanoic acid by a haloform reaction on diacetone acrylamide and by a Ritter reaction between acrylonitrile and β,β‐dimethylacrylic acid is reported. The properties of this crystalline monomer and its homopolymer are also reported.
Sulfur‐containing polymers. VI. Preparation of poly[alkylene bis(oxycarbonyl) disulfides] and related polymers
Authors: Kobayashi Norio , Fujisawa Tamotsu 
Published: April 2003

AbstractPoly[alkylene bis(oxycarbonyl) disulfides] have been prepared for the first time by the reductive coupling of alkylene bis(oxycarbonylsulfenyl chlorides). Potassium iodide and a variety of transition metals or their salts were employed as reducing agents. Of these potassium iodide and cuprous chloride gave the best results. Pyrolysis, desulfurization. and thiol‐induced fragmentation of the polymers have been studied. Homologous polymers, i.e., monosulfide polymer, trisulfide polymer, and tetrasulfide polymer, have been also synthesized. Monosulfide and disulfide polymers were highly crystalline solids. Trisulfide polymer was a white solid with a low degree of crystallinity. These polymers were soluble in chloroform and dichloromethane. Tetrasulfide polymer was a crystalline yellow solid and was soluble only in HMPA.
Polymer effect on electron‐donating character of polymeric donor. I. Formation of charge‐transfer complex between polymers containing N,N‐dimethylaniline group and maleic anhydride
Authors: Iwatsuki Shouji , Arai Kiyotaka 
Published: April 2003

AbstractThe difference in electron‐donating character between polymeric and monomeric donors in their charge‐transfer‐complex formation reactions was studied to clarify the so‐called polymer effect in such reactions. Systems containing maleic anhydride and copolymers of N,N‐dimethyl‐p‐aminostyrene (ASt) with styrene, which were prepared by a conventional free‐radical polymerization technique, were found to be suitable for this purpose. In correlations between the mean sequence length μASt of the ASt units in the copolymers and the lowest energy of their charge‐transfer transition (λmax) or the association constant of their complex formation KCT, a bathochromic shift in λmax and an increase in KCT with increasing μASt of copolymers are found. Moreover, there is a difference in their modes of μASt dependence. It was concluded from these results that the electron‐donating character of the dimethylaniline group increases with increasing number of groups attached on one polymer chain. Also, there is an interaction among neighboring functional groups on one polymer chain. The interaction may be regarded as a kind of polymer effect. In addition, the difference in μASt dependence between λmax and KCT and also thermodynamics of the complex formation are discussed.
Side‐chain crystallinity. V. Heats of fusion and melting temperatures on monomers whose homopolymers have long side chains
Authors: Jordan Edmund F. 
Published: April 2003

AbstractHeats of fusion and melting temperatures were obtained for selected monomeric n‐alkyl acrylates, N‐n‐alkylacrylamides, and vinyl esters. The corresponding thermodynamic parameters for homopolymers, derived from these monomers, had been reported previously from this laboratory. The α‐hexagonal crystal modification was indicated near the melting point for the higher n‐alkyl acrylates, but a β form was stable at low temperatures for the entire series. The magnitude of the heats of fusion indicated β polymorphs for vinyl esters in support of x‐ray diffraction analysis from the literature. Because hexagonal crystal geometry prevailed in all reported homopolymers having long side chains, greater emphasis was placed on thermodynamic data for monomers exhibiting this crystal modification. Accordingly, a convergence temperature was estimated statistically for the α‐hexagonal crystal modification of these systems and appropriate literature values of the n‐alkanes and ethyl esters. The convergence temperature was computed to be 135°C, uncorrected for the entropy of disorientation. The anomalously large interfacial end‐packing‐defect energy of the poly(n‐alkyl acrylates) and the poly‐N‐n‐alkylacrylamides was shown to be associated with a high energy barrier to molecular transport in the melt as the vitreous state was approached. In support of this conclusion, similarity of the glass and melting transition temperatures of these homopolymer homologs occurred near their critical side‐chain lengths, below which the homopolymers are amorphous. A special critical requirement of nucleus length was not indicated from rough estimations of nucleation parameters for the poly(n‐alkyl acrylates). These findings lent increased, but still not unqualified, support to an x‐ray diffraction study from the literature. The latter had specified the inclusion of the entire side chain and the main‐chain units in the crystal lattices of the higher poly(n‐alkyl acrylates).
Self‐regulating polycondensations. IV. Ordered oxadiazole‐imide copolymers
Authors: Preston J. 
Published: April 2003

AbstractOrdered oxadiazole‐imide copolymers are prepared from simple aminobenzhydrazide monomers by a step‐wise reaction which begins with the condensation of a diacid chloride to produce in situ a diamine containing hydrazide linkages. The in situ diamine is then reacted with a dianhydride to yield an ordered hydrazide‐amic‐acid copolymer; this precursor is converted by heating to the ordered heterocycle copolymer. Polymers prepared via this manner are identical in properties to those obtained by the reaction of a dianhydride with a diamine containing hydrazide linkages preformed by a straight forward synthesis from a dinitro precursor. Fibers spun from the soluble precursor polymers were converted via cyclodehydration to thermally stable fibers. Another polyoxadiazole‐imide was produced in similar fashion; e.g., an aminobenzhydrazide was reacted with the acid chloride of trimellitic anhydride to yield an in situ AB monomer which was polymerized to yield a precursor polyhydrazide‐amic‐acid, which in turn was converted by cyclodehydration to an AB type polyoxadiazole‐imide. Additional examples are cited of the formation of polymers from the in situ intermediates produced by the “self‐regulating” reaction of aminobenzhydrazides with acid chlorides followed by polycondensation with difunctional monomers.
Poly[bis(phosphinatoalanyl)phosphonates]
Authors: Flagg Edward E. , Schmidt Donald L. 
Published: April 2003

AbstractA series of coordination polymers, poly[bis(phosphinatoalanyl)phosphonates], [X(Y)AlOP(R)(O)OAl(Y′)(X′)]n, were synthesized in which the terminal alanyl substituents (X,Y,X,′Y′) consisted of phosphinato (OPRR′O) or fluoro (F) moieties. The properties of the polymers were primarily dependent upon the type of terminal substituent and the hydrocarbon moieties (R,R′) on phosphorus. Polymers with four phosphinato moieties gave molecular weights M̄n to 120000 with intrinsic viscosities [η] from 1.5 to 18; the corresponding solids were partially crystalline, melted before decomposition, and were film‐forming when larger phosphorus substituents were incorporated. Sequential replacement of the phosphinato moieties with fluorine resulted in molecular weights below 10000 and low viscosities. The properties of the polymers are examined, and the roles of substituents on probable structures are discussed.
Polymerization of butadiene initiated by the 1:1 chelate of n‐butyllithium and N,N,N′,N′‐tetramethylethylenediamine
Authors: Hay J. N. , McCabe J. F. 
Published: April 2003

AbstractEvidence is given for the species involved in the initiation and propagation steps in the polymerization of butadiene with n‐butyl lithium: tetramethylethylene diamine (TMEDA) as being the monomeric butyl lithium and the solvated ion pair, (A),
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respectively. Species A is also produced on the metalation of polybutadiene with butyl lithium: TMEDA.
Reaction of propylene sulfide with nitrogen‐containing polymers
Authors: Lautenschlaeger F. , Zeeman P. 
Published: April 2003

AbstractA convenient route for the introduction of mercaptan groups into nitrogen‐containing polymers is provided by addition of propylene sulfide to such polymers. The reaction with polyethylenimine, Versamid 140, and nylon 11 was investigated. In contrast to the reaction of polyethylenimine with propylene oxide, only limited initiation of the grafting reaction on the polymeric amine is achieved, as evidenced by a low mercaptan functionality of the grafted products.
Thermal and autoxidation reactions of poly‐3‐methylenecyclobutene and poly‐1‐methyl‐3‐methylenecyclobutene
Authors: Wu Charles C. , Lenz Robert W. 
Published: April 2003

AbstractThe thermal ring‐opening reactions, autoxidation and hydrogenation of polymethy‐lenecyclobutene (PMCB) and poly‐1‐methyl‐3‐methylenecyclobutene (PMMCB), were investigated. Both polymers were prepared by cationic polymerization and consisted almost entirely of 1,5‐repeating units containing cyclobutene rings in the polymer backbone. Both polymers showed well behaved exothermic processes at elevated temperatures which apparently resulted in crosslinking. These processes were investigated by differential scanning calorimetry and interpreted to involve thermal ring‐opening reactions. Autoxidation occurred very rapidly in PMCB but much more slowly in PMMCB as predicted by Bolland's rules. Attempts to hydrogenate the cyclobutene rings in both polymers resulted in the occurrence of hydrogenolysis in PMCB and little or no reaction with PMMCB for a Pd‐catalyzed reaction and partial hydrogenation of the latter for a diimide reaction.
Block copolymerization. V. Block anionic polymerization of lactams
Authors: Yamashita Yuya , Matsui Hisashi , Ito Koichi 
Published: April 2003

AbstractBischloroformates of hydroxy‐terminated poly(tetramethylene glycol) (PTG) and polystyrene (PSt) were prepared and used as the initiators for the anionic polymerization of α‐pyrrolidone and ε‐caprolactam in bulk at 30°C and 80°C, respectively. Initiation efficiency was sufficiently high to give well‐defined nylon–PTG(or PSt)–nylon block copolymers. Both the yield and the viscosity of the block copolymer increased with polymerization time up to 50% conversion of the lactam.
γ‐Irradiation of polystyrene emulsions
Authors: Rudin Alfred , Chau T. C. 
Published: April 2003

AbstractAqueous polystyrene emulsions were subjected to γ‐irradiation at 30°C and 0.6 Mrad/hr dose rate. Analogy with water‐soluble systems suggests that such conditions might suppress chain scission and favor crosslinking. The (extrapolated) infinite‐dose gel content and gel‐permeation analysis of the polymer in the pre‐gel region indicate that the extent of chain scission was negligible. The G (crosslink) value obtained from the dose for incipient gelation and molecular weight variations in the pre‐gel region is 0.051. Charlesby‐Pinner plots were linear, but linearity cannot be construed as indicating that chain scission has produced an effective random molecular weight distribution. Our results are consistent with the conclusions that crosslinking events are random and directly proportional to dose. The probability that a given crosslink is effective in increasing the gel content decreases with dose past the incipient gel point, however, because of cyclization on preformed gel. The crosslink density/dose ratio is a decreasing function of dose in this range. Attempts to predict dose–gel relations with assumptions of various initial molecular weight distributions were unsuccessful, possibly because of the neglected influence of cyclization on the measured gel content.
Computer simulation for the cooligomerization system
Authors: Tsuchida Eishun , Mishima Kunio , Kitamura Kiwamu , Shinohara Isao , Mimashi Setsuo 
Published: April 2003

AbstractIn order to clarify the kinetic features of the styrene (A)–methyl methacrylate (B)–CCl4(S) cooligomerization system, a computer simulation was carried out. The experimental data on the degree of polymerization and the deviation of the cooligomer composition from the statistical steady‐state composition were comparatively well explained by calculations based on the kinetic equations derived from the assumed reaction scheme and the values of the velocity coefficients, although the values of the four velocity coefficients in the initiation step and the velocity coefficient of the termination by the coupling of two solvent radicals were estimated. The results of the calculation of the rate of each component reaction show that the following two reactions are the most important in the initiation and in the transfer and termination steps when the [S]/([A] + [B]) ratio is large:

where, A, A*, and P are styrene, polystyryl radical, and the cooligomer, respectively. Moreover, it was concluded that the deviation of the cooligomer composition from the statistical steady‐state composition was caused by these two reactions.
Simplified treatment of cooligomerization kinetics
Authors: Tsuchida Eishun , Kitamura Kiwamu , Shinohara Isao 
Published: April 2003

AbstractEquations for the degree of polymerization and the cooligomer composition in the styrene (A)–methyl methacrylate (B)–CCl4(S) system were derived from the assumed reaction scheme by the use of some assumptions for simplification, and their appropriateness was examined. The chain transfer constants of the growing radicals of styrene (CSA) and methyl methacrylate (CSB) to CCl4, which were estimated from the apparent chain transfer constants CSAB in the cooligomerization system, agreed with the homooligomerization values. This means that the degree of the polymerization of the cooligomer can be expressed by the equation:

where Pn is the degree of polymerization of the cooligomer and PnO is that when no chain transfer agent (CCl4) is added; rA and rB are the monomer reactivity ratios of monomers A and B in this system. The cooligomer composition deviated from the statistical steady‐state composition on the low molecular weight side, and this deviation was explained by the equation: