bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of oxygen on the radical polymerization of acrylamide in ethanol and water
Authors: George M. H. , Ghosh A. 
Published: April 2003

AbstractThe polymerization of acrylamide has been studied in ethanol at 80°C with 2,2′‐azobisisobutyronitrile (AIBN) as the initiator, and also in water at 60°C with 4,4′‐azobis‐4‐cyanopentanoic acid (ACV) as the initiator. For the first system, it was found, approximately, that the well defined in duction period showed an inverse dependence on both the initial monomer and initiator concentrations, but was directly proportional to the square root of the initial oxygen concentration. For the second system, the rate of oxygen uptake was approximately directly proportional to the monomer and initiator concentration but independent of the oxygen concentration. The results obtained for these two systems are compared.
Reactivity of polymer substituents. II. Aminolysis of p‐nitrophenyl acrylate copolymers with acrylamide or N,N‐dimethylacrylamide in aqueous solution
Authors: Su Chin‐Pao , Morawetz Herbert 
Published: April 2003

AbstractRates of the benzylaminolysis of acrylamide and dimethylacrylamide copolymers with a small amount of p‐nitrophenyl acrylate in water solution were compared with the analogous reaction of p‐nitrophenyl isobutyrate. Rates of the dimethylacrylamide copolymer and analog were also measured in methanol. The copolymer reactions were much slower than those of the analog, in contrast with results obtained in dioxane. It was found that the reaction of the analog is much more sensitive to the medium than the reaction of the polymer, because the “effective solvent medium” in the polymer domain is largely determined by properties of the polymer chain backbone.
Modification of properties of ion‐exchange membranes. IV. Change of transport properties of cation‐exchange membranes by various polyelectrolytes
Authors: Sata Toshikatsu 
Published: April 2003

AbstractA change in electrodialytic transport properties of various cation exchange membranes was observed after the membranes had been adsorbed or ion‐exchanged with various cationic polyelectrolytes. Transport properties measured in this report were the relative transport number of calcium ion to sodium ion PCaNa, the current efficiency of cations, and the electric resistance of the membrane during the electrodialysis. Weakly basic and strongly basic cationic polyelectrolytes of various molecular weights were used. Though PCaNa of any cation exchange membrane decreased by the adsorption or ion exchange of any cationic polyelectrolyte, the degree of the decrease in PCaNa changed with species and molecular weight of polyelectrolytes and species of cation‐exchange membranes. Weakly basic polyelectrolytes and low molecular weight, strongly basic polyelectrolytes were effective in producing a marked decrease in PNaCa of any cation exchange membrane. The effect of strongly basic polyelectrolytes of high molecular weight on PCaNa was weak in most cases. However, if it was possible to make the polyelectrolyte adhere to the surface of the membrane to form a compact coiled structure, any cationic polyelectrolyte was effective in producing a remarkable decrease in PCaNa of any cation‐exchange membrane.
ESCA applied to polymers. XIX. Investigation of polymer films produced by inductively coupled RF plasmas excited in vinylidene fluoride
Authors: Clark D. T. , Shuttleworth D. 
Published: April 2003

AbstractFilms of known thickness have been prepared in situ by radio frequency (RF) glow discharge techniques with the use of vinylidene fluoride as the monomer. A description of the structure as revealed by ESCA is presented and comparison drawn with related work. Electron mean free paths have been measured as a function of kinetic energy corresponding to photoemission from the C1s (967 eV), F1s (563 eV), and F2s (1220 eV) levels of the plasma‐polymerized material. The results confirm that for a given class of materials such as polymers, escape depths are not strongly dependent on fine details of structure and bonding and moreover that mean free paths are comparable with those measured for typical metals and semiconductors.
Anionic polymerization of p‐diisopropenylbenzene in tetrahydrofuran: Reactivity of pendent double bond
Authors: Okamoto Akio , Mita Itaru 
Published: April 2003

AbstractAnionic polymerization of p‐diisopropenylbenene was found to be an equilibrium polymerization not only with respect to the monomer but also with respect to the pendent double bond. The polymerization was studied from kinetic as well as from the thermodynamic point of view, especially to ascertain the reactivity of the pendent double bond as compared with the double bond of monomeric analog. It was shown that the crosslinking rate constant of the pendent double bond is lower by about three to four orders than the propagation rate constant of the monomeric analog. The rate of cyclization was also very slow. From the equilibrium, the heat and entropy of polymerization of the monomer were determined as ΔHss = −5.8 kcal/mole and ΔSss = −18.0 cal/deg mole, respectively, and those of the pendent double bond as ΔHss = −6.3 kcal/mole and ΔSss = −27.8 cal/deg mole. When compared with the polymerization of α‐methylstyrene, the low thermodynamic polymerizability of the pendent double bond is attributed to the low heat of polymerization, which may arise from the large steric hindrance of neighboring groups. The effect is much smaller for the equilibrium than for the rate of polymerization, however.
Esterolytic activity of imidazole‐containing polymers. Synthesis and characterization of copoly[1‐alkyl‐4‐ or 5‐vinylimidazole/4(5)‐vinylimidazole] and its catalytic activity in the hydrolysis of p‐nitrophenyl acetate
Authors: Overberger C. G. , Kawakami Y. 
Published: April 2003

AbstractThe water‐soluble monomers, 1‐methyl‐4‐vinylimidazole, 1‐methyl‐5‐vinylimidazole, 1‐ethyl‐5‐vinylimidazole, and 1‐propyl‐5‐vinylimidazole have been synthesized, polymerized, and copolymerized with 4(5)‐vinylimidazole. The copolymers were characterized by 14C‐labeling, NMR, pKa determination and viscosity measurements. The monomer reactivity ratios determined by 14C counting are r1 = 1.04; r2 = 0.94 [M1 = 4(5)‐vinylimidazole, M2 = 1‐methyl‐4‐vinylimidazole] and r1 = 1.01; r2 = 0.86 [M1 = 4(5)‐vinylimidazole, M2 = 1‐methyl‐5‐vinylimidazole]. The esterolytic activity of the copolymers for the hydrolysis of p‐nitrophenyl acetate (PNPA) at pH 7–8 in 28.5% ethanol–water was higher than that of the mixtures of homopolymers. At pH 5–6 the esterolytic activities of the copolymers and the mixtures were similar. The most efficient esterolytic activity for PNPA hydrolysis at pH 7.11 in 28.5% ethanol–water occurred for copolymers containing 75 mole % 4(5)‐vinylimidazole and for copolymers containing 1‐methyl‐4‐vinylimidazole rather than 1‐methyl‐5‐vinylimidazole.
Catalysis by polyethylenimine derivatives with two functional groups
Authors: Nango M. , Klotz I. M. 
Published: April 2003

AbstractModified polyethylenimines have been prepared containing imidazole and dimethylamine functionalities for catalytic purposes, as well as apolar groups to increase binding. The cooperative effect of the two functionalities increases the catalytic effectiveness of these polymers some 2–20‐fold, depending on the kinetic parameters being compared.
Polymerization of cyclic esters of phosphoric acid. VI. Poly(alkyl ethylene phosphates). Polymerization of 2‐alkoxy‐2‐oxo‐1,3,2‐dioxaphospholans and structure of polymers
Authors: Libiszowski Jan , Kałużynski Krzysztof , Penczek Stanisław 
Published: April 2003

AbstractFive‐membered cyclic esters of phosphoric acid of the general formula: CH2CH(R)OP(O)‐(OR′)O polymerize readily to solid, soluble polymers of high molecular weight without any rearrangement known for various tri‐ and pentavalent organophosphorus monomers. 1H‐, 13C‐, and 31P‐NMR spectra of polymers confirmed their linear structure:
magnified image
where R is H, with R′ = CH3, C2H5, n‐C3H7, i‐C3H7; n‐C4H9, CCl3CH2, or C6H5, or R is CH2Cl and R′ is C2H5. The use of n‐C4H9Li, (C5H5)2Mg, or (i‐C4H9)3Al as initiators leads to polymers with Mn = 104–105.
Selective initiation of nonconjugated dienes containing electron donor–electron aceptor systems. I. Synthesis of vinyl ether–β‐nitrostyrene monomers
Authors: Nash Jr. James L. , Thompson Ronald E. , Schwietert James W. , Butler George B. 
Published: April 2003

AbstractThe objectives of this work were to synthesize, characterize, and conduct a polymerization study on a set of ideal crosslinking monomers. The monomers studied are the three isomers of (2‐vinyl‐oxyethoxy)‐β‐nitrostyrene. Such monomers contain both the electron‐donating vinyl ether moiety and the electron‐accepting β‐nitrostyrene moiety. A study of the spectral properties of these monomers was carried out in an effort to determine whether there was a contribution to the structure through an intramolecular interaction of the nature of a charge‐transfer complex. Such studies have led to little or no support for such an interaction. As model compounds for comparison of spectral properties, the monomer series, o‐, m‐, and p‐(2‐ethoxyethoxy)‐β‐nitrostyrenes were synthesized and characterized as above. A comparison of the spectral and physical properties of these two series of compounds show that there are significant differences suggestive of the interactions proposed. However, since these discrepancies are small in most cases, it is not possible at present to correlate them specifically with the postulated intramolecular interactions.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. III. Synthesis of vinyl ether–styrene monomers
Authors: Thompson Ronald E. , Butler George B. 
Published: April 2003

AbstractIn a continuation of our studies on nonconjugated dienes containing electron donor–electron acceptor systems which may function as model crosslinking monomers, we here report the synthesis of the series, 2‐, 3‐, and 4‐(2‐vinyloxyethoxy)styrenes. The dipole moments μ, infrared and ultraviolet absorption properties, refractive indices nD30, molar refractions (MRD), and optical exaltations of the compounds were determined. In order to establish whether any intramolecular electronic interactions, e.g., intramolecular charge‐transfer complexes, contribute to the structure and properties of these compounds, 2‐ and 4‐(2‐ethoxyethoxy)styrenes were also prepared, and their properties compared with those of the vinyloxy series. While there are differences in certain of the properties of these two groups of monomers, these differences are not sufficiently large to permit definite correlations with the proposed interactions.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. IV. Polymerization of vinyl ether–styrene monomers
Authors: Chu Shaw‐Chang , Butler George B. 
Published: April 2003

AbstractThree isomeric nonconjugated dienes, o‐, m‐ and p‐(2‐vinyloxyethoxy)styrenes, were selectively polymerized by anionic or radical initiators through the styryl double bond while leaving the vinyl ether moiety intact. The anionic‐initiated polymeric products are of high molecular weight and narrow molecular weight distribution as characterized by membrane osmometry and gel‐permeation chromatography, respectively. These polymers were subsequently crosslinked by cationic initiators via the vinyl ether moiety on the polymer side chains. Acid‐catalyzed hydrolysis of the poly(2‐vinyloxyethoxy)styrenes yielded their respective hydroxy‐containing polymers, polyvinylphenoxyethanols. The latter were physically and spectroscopically identical to authentic samples prepared by radical polymerization of the corresponding vinylphenoxyethanols, which, in turn, were synthesized by hydrolysis of the (2‐vinyloxyethoxy)styrenes. The polyvinylphenoxyethanols were shown to undergo many chemical transformations, such as esterification with 3,5‐dinitrobenzoyl chloride, cyanoethylation, and urethane formation.
Constitution moléculaire d'α,ω‐difluoropolydiméthyl‐N‐méthylsilazanes. Equilibres obtenus par une réaction de redistribution
Authors: Pace Simonne C. 
Published: April 2003

AbstractUnlike the α,ω‐dihalogenopolydimethylsiloxanes, the α,ω‐dichloropolydimethyl‐N‐methylsilazanes show a net preference for cyclic species with respect to linear structures at equilibrium. The aim of this study is to evaluate the perturbations in the molecular constitution of these α,ω‐dihalogenopolydimethyl‐N‐methylsilazanes resulting from the substitution of the terminal chlorine atoms by fluorine atoms. This polymeric family was prepared by reacting (CH3)2SiF2 with nonamethylsilazane [(CH3)2SiNCH3]3. The redistribution of the fluorine atoms with the bridging methylimino groups reached an equilibrium after about 5 months' heating at 150°C for all the samples prepared. The relative abundance of the various molecular species and fragments at equilibrium was deduced from the quantitative analysis of the proton nuclear magnetic resonance (NMR) spectra. The molecular constitution at equilibrium is described by two constants. The first, K = [neso] [middles in chains]/[terminal moieties]2 = (2.8 ± 0.8) 10−2, shows that the presence of terminal fluorine atoms is unfavorable to the formation of short chains. On the other hand, the trimeric cyclic species [(CH3)2SiNCH3]3 are found to be highly favored (K°3 = 550 ± 100 mole/liter). These observations further confirm that the equilibrium constants which control the noncyclic part of polymeric families depend little on the functionality of the substituents exchanged [for example, on changing from N(CH3)2 to NCH3] when the reorganization heat order is one.
Glass transition in polyesteramides
Authors: Akçatel P. , Jasse B. 
Published: April 2003

AbstractThe glass transition of three different polyesteramides, polyundecanamide‐undecanoates, polyundecanamide‐nonanoates, and polyundecanamide–p‐methylbenzoates has been investigated by differential thermal analyses. As the amino acid content in the polymer increases, the evolution of the glass transition temperature is strongly influenced by the comparative length and the stiffness of the two monomer units. The experimental data are discussed in terms of the disruption of a hydrogen‐bonded network in the amorphous regions of the copolymers.
Polymerization of monoallyl phthalate
Authors: Imai Itsuro , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractRadical polymerization of monoallyl phthalate (MAP) was conducted at 70, 80, and 90°C, benzoyl peroxide being used as an initiator. It was found that the analytical values of the polymer obtained were always lower than the calculated ones for MAP homopolymer and nearly constant regardless of the polymerization conditions. From the detailed investigation it was concluded that the results are due to the formation of polymer including about 20 mole % of allyl alcohol units; such allyl alcohol units might be incorporated into the polymer through propagation accompanied by partial elimination of phthalic anhydride.
Electron diffraction studies of multilayers of vinyl stearate
Authors: Day David , Lando Jerome B. 
Published: April 2003

AbstractMultilayers of vinyl stearate monomer were built up using the Blodgett technique. These were observed at low temperatures by electron diffraction and hexagonally twinned diffraction was observed. The reflections were indexed to be the (200) and (112) resulting from the pure vinyl stearate monoclinic cell. Hexagonal twinning was attributed to three preferred growth directions dictated by the original monolayer order–disorder packing.
Effects of phosphorus oxychloride and phenylphosphonic dichloride on the radical polymerization of methyl methacrylate and styrene
Authors: Taninaka Takumi , Uemura Hideaki , Iwamoto Kohji , Minoura Yuji 
Published: April 2003

AbstractEffects of pentavalent phosphorus compounds on the radical polymerization of methyl methacrylate (MMA) and styrene (St) were studied. Phosphorus oxychloride (Cl3PO) and phenyl‐phosphonic dichloride (C6H5Cl2PO) were used. Polymerization was carried out in benzene at 50°C by the standard solution method, α,α′‐azobisisobutyronitrile (AIBN) being used as the initiator. In the polymerization of MMA, both phosphorus compounds increased the rate of polymerization. NMR spectral data suggested that this increasing effect was due to the complex formation between each phosphorus compound and MMA monomer. In the case of polymerization of St, NMR data also indicated the formation of a complex between the phosphorus compound and St monomer. Both phosphorus compounds showed an increasing effect for the rate of polymerization. Though these increasing effects could be explained by the complex formation, the polymerization of St in the presence of Cl3PO was especially found to be due to the cationic polymerization initiated simultaneously by Cl3PO in addition to the radical polymerization. These phosphorus compounds acted as chain‐transfer agents in both polymerization systems. The parameters (Qtr,etr) which indicate the reactivity of a chain‐transfer agent were calculated from the observed values of chain‐transfer constant for both polymerization systems.
Das Monte Carlo‐studium der binären copolymerisation in der annahme des vorletzten Effektes. I. Theorie, MEMORY 5‐programm, anwendungen
Authors: Motoc I. , Vancea R. , Holban St. 
Published: April 2003

AbstractThis paper presents a mathematical model (using the Monte Carlo technique) for the building of a binary copolymer considering the penultimate effect. One discusses the algorithm and the computer implementation. Finally, two applications are given. The purpose of this series of papers is to provide a Monte Carlo method to compute the sequence distribution for the hypothesis of penultimate effect (program MEMORY 5), ultimate effect (program MEMORY 3), and copolymerization with depolymerization (program MEMORY 6).
Das Monte Carlo‐studium der copolymerisation der ester der benzylidencyanessigsäure mit styrol
Authors: Motoc I. , Vancea R. , Holban St. 
Published: April 2003

AbstractThe Monte Carlo study of copolymerization of styrene with four esters of benzylidenecyanoacetic acid has pointed out that (a) for methyl and hexyl esters one cannot decide among the ultimate and penultimate effect (using copolymer composition and Fischer statistic), and (b) cyclohexyl and benzyl esters copolymerize following the kinetics of penultimate effect. Finally, the most probable sequence distribution in the studied copolymers is presented.
Random copolymerization of acetylenic monomers and 1,3‐dienes
Authors: Furukawa Junji , Kobayashi Eiichi , Kawagoe Takahiro 
Published: April 2003

AbstractCopolymerization of acetylenic monomers and 1,3‐dienes was carried out by use of nickel naphthenate–diethylaluminum chloride catalyst. The molecular weight of the copolymers is rather low, and the copolymers are suitable as prepared for direct use as coating vehicles. In the system of acetylene and 1,3‐dienes, the order of the copolymerization rate decreases in the following order: butadiene > isoprene > 2,3‐dimethylbutadiene > chloroprene. 1,3‐Dienes substituted at 1‐and/or 4‐position were scarcely copolymerized with acetylene. Methylacetylene and dienes tend to form cyclized copolymers. In the system of phenylacetylene and dienes, polyphenylacetylene was the main product; the copolymer was not obtained. The copolymer composition and the sequence distribution of linear copolymers were evaluated by 1H‐NMR spectra. Comparison of dyad fractions of copolymers evaluated from NMR spectra and those calculated by assuming random polymerization indicated that the copolymers of acetylene and dienes were random, and that the copolymers of methylacetylene and dienes were somewhat blocky. The coordination of monomers on the catalyst may play an important role in controlling the copolymerizability.
Polymerization of propene with organomagnesium–reduced titanium (IV) chloride‐based catalyst
Authors: Gardner Kevin , Parsons Ian W. , Haward Robert N. 
Published: April 2003

AbstractA kinetic study of the polymerization of propene by use of magnesium–reduced titanium (IV) chloride‐based catalyst systems has been carried out and the tacticities and molecular weights of the polymers formed have been investigated. The rate constant for the formation of isotactic polymer is estimated to be 69 ± 18 dm3/mole sec and that for the atactic polymer to be 12 ± 5 cm3/mole sec. The number of active sites producing atactic polymer has been determined as 3 ± 1% of the Ti atoms present, whereas sites producing isotactic material amount to 0.36 ± 0.13% of the Ti atoms. The overall tacticity of the polymers corresponds to approximately 40% isotactic material. This figure is barely affected by heat treatment of the catalyst.
Reactions of tert‐butoxy radicals with vinyl monomers
Authors: Encina M. V. , Rivera M. , Lissi E. A. 
Published: April 2003

AbstractTert‐butoxy radicals generated in the photolysis of di‐tert‐butyl peroxide in benzene at 25°C react with vinyl monomers by double‐bond addition and, in most cases, also by competitive hydrogen abstraction. The rate constant for the double‐bond addition changes by a factor of 17 between isoprene, which shows the highest reactivity, and the methacrylate derivatives, which are the least reactive of the monomers considered. The fraction of tert‐butoxy radicals that react by hydrogen abstraction varies considerably with the monomer structure, ranging from 0.9 (cyclohexyl methacrylate) to less than 0.05 (styrene and conjugated diolefins). In the methacrylate derivatives, most of the hydrogen abstraction takes place, not in the α‐methyl group, but in the alkyl chain.
Structure and extinction of counterflow diffusion flames above condensed fuels: Comparison between poly(methyl methacrylate) and its liquid monomer, both burning in nitrogen–air mixtures
Authors: Seshadri K. , Williams F. A. 
Published: April 2003

AbstractSince poly(methyl methacrylate) is known to depolymerize largely to its monomer when heated, the chemical kinetics in the gaseous diffusion flame produced by this polymer in a fire may coincide with that of burning liquid methyl methacrylate. To test this hypothesis, flat diffusion flames were probed and extinguished adjacent to surfaces of each of these fuels. Profiles of temperature and of concentrations of stable chemical species are reported, as are gas velocities of approach flow required to produce extinction for various oxygen/nitrogen ratios of the stream. Results revealed structural differences attributable to differing thermal properties of the fuels. Many fuel species were observed in the gas phase, their profiles being partially rationalized on the basis of a suggested decomposition mechanism for gaseous methyl methacrylate. Overall kinetic parameters for gasphase combustion, obtained by use of extinction results in a previously developed theory, are nearly the same for the polymer and monomer but appear to differ by amounts exceeding experimental uncertainties. It is suggested that this may be traced to small differences in fuel species leaving the condensed phase which, for the polymer, is covered by a thin, two‐phase region.
Photolytic and radiolytic polymerization of N‐ethylmaleimide in cyclohexene
Authors: Wipfelder E. , Heusinger H. 
Published: April 2003

AbstractIrradiation of N‐ethylmaleimide (NEMI) in cyclohexene (CH) with ultraviolet light or γ rays gives rise to polymer formation. Separation of the components by liquid chromatography and determination of their structure of pyrolysis—gas chromatography (GC)–mass spectrometry (MS) coupling, infrared spectroscopy, and 13C‐ and 1H‐resonance spectroscopy show that the polymer produced in photolysis as well as in radiolysis consists of an almost alternating copolymer of NEMI and CH and small amounts of a NEMI homopolymer. Based on the experimental results, we propose a radical mechanism for copolymerization and an anionic mechanism for homopolymerization.