bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emulsion copolymerization of styrene and methyl methacrylate
Authors: Goldwasser J. M. , Rudin Alfred 
Published: April 2003

AbstractChain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10−5 for styrene polymerization and 0.4 × 10−5 for the methyl methacrylate reaction. Cross‐transfer reactions are important in this system; the sum of the cross‐transfer constants is 5.8 × 10−5. Reactivity ratios measured in emulsion were r1 (styrene) = 0.44, r2 = 0.46. Those in bulk polymerizations were r1 = 0.45, r2 = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval‐2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.
Magnesium chloride supported high‐mileage catalysts for olefin polymerization. I. Chemical composition and oxidation states of titanium
Authors: Chien James C. W. , Wu Jiun‐Chen , Kuo Chi‐I 
Published: April 2003

AbstractThe chemical composition of a MgCl2‐supported, high‐mileage catalyst has been determined at every stage of its preparation. Ball milling of MgCl2 with ethyl benzoate (EB) resulted in the incorporation of 95% of the EB present to give MgCl2·EB0.15. A mild reaction with a half‐mole equivalent of p‐cresol (PC) at 50°C for 1 h resulted in near quantitative retention of p‐cresol by the support. The composition is now approximately MgCl2·EB0.15P̌0.5. Addition of an amount of AlEt3 corresponding to half‐mole equivalent of p‐cresol liberated one mole of ethane per mole of p‐cresol, thus signaling quantitative reaction between the two components. The support contains on the average one ethyl group per Al. Further reaction with TiCl4 resulted in the incorporation of titanium of approximately 8, 38, and 54% in the oxidation states of +2, +3, and +4, respectively. The ratio of Al to Ti in the catalyst lies in the range of 0.5–1.0. Only 19% of all the Ti+3 species in the catalyst can be observed by electron paramagnetic resonance (EPR); these are attributable to isolated Ti+3 complexes. The remaining EPR silent Ti+3 species are believed to be bridged to another Ti+3 by Cl ligands. The total Cl content is equal to the sum of 2 × Mg + 3 × Al + 3.5 × Ti. Most of the p‐cresol moiety apparently disappeared from the support, leaving much of ethyl benzoate in the catalyst. Activation with AlEt3/methyl‐p‐toluate complex reduces 90% of the Ti+4 in the catalyst to lower oxidation states. The ester apparently moderates the alkylating power of AlEt3 to avoid excessive formation of divalent titanium sites. There appears to be a constant fraction of 1/4–1/5 of the titanium which is isolated and the remainder is in bridged clusters independent of the oxidation states of titanium.
Synthesis and characterization of a new conjugated polymer: Polytrifluoromethylacetylene
Authors: Rubner Michael , Deits Walter 
Published: April 2003

AbstractPolytrifluoromethylacetylene (PTFMA) was synthesized from trifluoromethylacetylene (TFMA) using a PdCl2/DMF catalyst solution or the anionic initiator n‐butyl lithium. Although PdCl2 proved to be an effective catalyst for the polymerization of TFMA, long reaction times and poor yields made characterization of the resultant polymer difficult. The use of n‐butyl lithium, on the other hand, resulted in high yields of PTFMA in relatively short reaction times. The results of thermal analysis and the effects of n‐ and p‐type doping on the electrical conductivity of the polymer are discussed.
Polymerization ability of cis‐ and trans‐4,5‐epoxy‐2‐pentenal with ionic and free radical initiators. Cyclopolymerization of the cis isomer
Authors: Yokoyama Y. , Hall H. K. 
Published: April 2003

AbstractThe behavior of the readily available cis‐ (1) and trans‐ (2) 4, 5‐epoxy‐2‐pentenals toward classical cationic, anionic, and free radical initiators has been examined. Only the cationic polymerization of 1 gave soluble polymer of moderate molecular weights. This polymer possessed predominantly the cyclopolymerized furanose structure 12. Cationic initiation of 2 and anionic initiation of both 1 and 2 gave only crosslinked materials, and free radical initiators with 1 and 2 gave no polymer.
Reaction of poly(vinyl chloride) with electrogenerated superoxide anion
Authors: Osawa Zenjiro , Uchida Yoshihito 
Published: April 2003

AbstractReaction of poly(vinyl chloride) (FVC) with electrogenerated superoxide anion was carried out in a mixed solvent of tetrahydrofuran (THF) and dimethylformamide (DMF), mostly at 40°C, under a nitrogen stream. The results obtained were compared with those in an earlier article,1 in which the use of potassium superoxide was described. Reaction of PVC with electrogenerated superoxide anion took place easily and the yield and molecular weight of the recovered polymer decreased appreciably. Functional groups formed in PVC treated with electrogenerated superoxide anion were similar to those in PVC treated with potassium superoxide; that is, hydroxy (ca. 3400 cm−1), conjugated carbonyl groups (ca. 1675 cm−1), and polyene structures (ca. 1600 cm−1) were observed. In addition, a new peak, probably due to nonconjugated aldehyde groups, was observed at 1725 cm−1. Ultraviolet (UV) spectra of PVC treated with electrogenerated superoxide anion showed that the polyene sequences formed in the polymer were shorter than octaene and that the octaene and that the octaene was formed only in the reaction at 60°C.
13C‐NMR sequence analysis. 19. Anionic copolymerization of γ‐butyrolactam, δ‐valerolactam, and caprolactam at low temperatures
Authors: Kricheldorf Hans R. , Coutin Bernard , Sekiguchi Hikaru 
Published: April 2003

AbstractCopolymerizations of pyrrolidone‐2 (γ‐butyrolactam) with piperidone‐2 (δ‐valerolactam) and azepinone‐2 (ε‐caprolactam) and the copolymerization of piperidone‐2 with azepinone‐2 were studied in bulk at 30 or 45°C. The sodium salt and the tetramethylammonium salt of pyrrolidone‐2 were used as catalysts and N‐acetylpyrrolidone‐2 as cocatalyst. The sequences of the resulting copolyamides were analyzed by means of 22.63‐MHz 13C‐NMR spectra. All sequences were nearly random in nature, yet copolymerizations of pyrrolidone‐2 favor slightly the formation of alternating sequences. Furthermore, the rate of incorporation of pyrrolidone is higher than that of the two comonomers in contrast to experiments at temperatures above 100°C. The influence of transamidation reactions on the sequences is discussed. Propagation/degradation equilibria involving N‐acyllactam chain ends were found to modify the initially formed, kinetically controlled sequences in direction of thermodynamically controlled ones.
Acidic peroxo salts: A new class of initiators for vinyl polymerization. III. Kinetics of polymerization of methyl methacrylate initiated by potassium monopersulfate catalyzed by Co(II)
Authors: Samal Rajani K. , Satrusallya S. C. , Nayak B. L. 
Published: April 2003

AbstractKinetics of the polymerization of methyl methacrylate by an acidic peroxo salt like potassium monopersulfate catalyzed by Co(II) have been investigated in aqueous medium, over the range of 35–50°C. The rates of polymerization (Rp) have been studied at various concentrations of monomer and initiator. The efficiencies of various metal salts in catalyzing the polymerization have been evaluated from the observed value of Rp. The effects of catalyst (CoSO4), initiator, monomer, and various concentrations of FeCl3 on Rp and percentage conversion have been studied. The end groups of the recovered polymers have been studied using standard methods. From the observed end groups and kinetic results, a reaction scheme has been proposed involving initiation by SO4· or OH· radicals, generated by the interaction of the initiator with cobalt sulfate and termination of the polymer chains by mutual combination.
Head‐to‐head vinyl polymers. VI. Preparation and characterization of head‐to‐head poly(allyl alcohol) and its esters
Authors: Quach Loc , Otsu Takayuki 
Published: April 2003

AbstractHead‐to‐head (H–H) poly(allyl alcohol) (PAA) was prepared by the LiAlH4reduction of H–H poly(methyl acrylate) obtained from the methylation of alternating copolymer of ethylene with maleic anhydride. H–H poly(allyl acetate) (PAAc) and H–H poly(allyl benzoate) (PABz) were further derived by means of its acylations. All of these three H–H polymers were characterized by IR, NMR, TGA, and PGC measurements. The corresponding head‐to‐tail (H–T) polymers were also prepared by a similar method from the conventional H–T polymer of methyl acrylate, and characterized to allow comparison with the H–H polymers. The softening temperatures of all H–H polymers were somewhat higher than those of the respective H–T polymers, probably suggesting that the H–H placements increased the stiffness of the polymers. Unlike poly(acrylic esters) reported previously, these H–H allyl polymers were found to degrade at temperatures slightly lower than the H–T polymers. On pyrolysis at 430°C, both PAAc and PABz were also observed to release predominantly acetic acid and benzoic acid, respectively, and small quantities of the corresponding allyl ester monomers. The molar ratios of acid to ester were substantially larger for H–H polymers.
Studies of the polymerization of diallyl compounds. XXXVII. Copolymerizations of diallyl phthalate with dialkyl fumarates
Authors: Matsumoto Akira , Kamigaki Hiroyuki , Oiwa Masayoshi 
Published: April 2003

AbstractDiallyl phthalate (DAP) was copolymerized with dialkyl fumarates, including diethyl fumarate (DEF), di‐n‐butyl fumarate (DBF), and di‐n‐octyl fumarate (DOF) by using 2,2′‐azobisisobutyronitrile as an initiator at 60°C. Both rate and degree of copolymerization were quite enhanced compared with the homopolymerization of DAP and the maximum rate was found at the molar ratio of 1:1 in the monomer feed. The cyclization of DAP was almost exclusively suppressed in the Copolymerization. Gelation was promoted from 25% of the gel‐point conversion for the DAP homopolymerization to 9% of the minimum one observed. Copolymerizability of DAP (M1) with dialkyl fumarates (M2) was quite high, with the following monomer reactivity ratios M2, r1, r2: DEF, 0.01, 1.25; DBF, 0.02, 1.01; DOF, 0.02, 0.96. These results are discussed in mechanistic detail.
Photoinitiated polymerization of methyl methacrylate with benzoin methyl ether. III. Independent photogeneration of the ether radical
Authors: Pappas S. Peter , Asmus Robert A. 
Published: April 2003

AbstractEvidence is presented for initiation of MMA polymerization by the α‐methoxybenzyl (ether) radical, photogenerated by H abstraction from benzyl methyl ether, utilizing benzophenone as the H‐ab‐stracting agent. The results support previous reports on the initiating ability of ether radical, photogenerated from 14C‐labeled benzoin methyl ethers. Independent generation of one or both of the radicals derived from unsymmetrical initiators is more broadly applicable. The potential utility of this technique for providing insights into the photoefficiencies of commercially important photoinitiators, which produce initiator radicals by intramolecular bond cleavage, is discussed.
Reactivities of monomers toward the 2‐cyano‐2‐propyl radical by NMR study of end groups in copolymers
Authors: Bevington J. C. , Huckerby T. N. , Hutton N. W. E. 
Published: April 2003

AbstractCopolymerizations of styrene (S) with methyl methacrylate (MMA) and methacrylonitrile (MAN) at 60°C were performed with azoisobutyronitrile as initiator, enriched in its methyl groups with 13C. From the NMR spectrum of a copolymer it is possible to compare the numbers of initiator fragments attached to the two types of monomer unit; this information can be used to study the competition between the monomers for capture of the radicals formed from the initiator. The velocity constants for addition of the 2‐cyano‐2‐propyl radical to S, MMA, and MAN are in the proportions 1:0.56:0.34; it is concluded that polar effects are of some importance in the reactions of the radical.
Radiation degradation of copolymers of methyl methacrylate and 3‐oximino‐2‐butanone methacrylate
Authors: Bowmer T. N. , Reichmanis E. , Wilkins C. W. , Hellman M. Y. 
Published: April 2003

AbstractCopolymers of methyl methacrylate and 3‐oximino‐2‐butanone methacrylate (OM) were investigated as deep‐UV and e‐beam resists. Their increased sensitivity relative to PMMA (up to 50 times) was correlated with the radiation chemical yields of the volatile products and main chain scissions. The degradation of these copolymers, activated by the 3‐oximino‐2‐butanone entity, is discussed in terms of energy absorption mechanisms and the subsequent scission reactions.
Microstructure and electric properties of elastomeric ionene‐TCNQ salts
Authors: Watanabe Masayoshi , Toneaki Nobuhiro , Takizawa Yoshio , Shinohara Isao 
Published: April 2003

AbstractThe elastomeric ionene polymers characterized by the alternating structure of the rigid polycation segments that contained 4,4′‐bipyridilium rings and the flexible polypropyleneoxide (PPO) segments were prepared as a function of chain length of the PPO segments. From the measurements of dynamic mechanical properties and x‐ray diffraction patterns of these ionenes and their 7,7,8,8‐tetracyanoquinodimethane (TCNQ) salts, a microheterogeneous structure of the PPO segments and the polycation‐TCNQ salts segments in the TCNQ salts was estimated. On the basis of this microstructure a change in the conductive and dielectric properties with an increase on the weight fraction of the PPO segments the TCNQ salts (Wf) were discussed. For the simple salts the values of resistivity (ρ) and activation energy of conduction (Ea) were increased with the increase in the value of Wf. The values of ρ for the complex salts also increased with the increase in the value of Wf, whereas the values of Ea were nearly constant (ca. 0.07 eV) until the value of Wf reached 0.8. Strong interaction between \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm TCNQ}^{-\atop\cdot}$\end{document} and TCNQ° molecules facilitated the formation of the continuous conduction columns and did not change their structure and properties. Dielectric constant (ε) of the TCNQ salts attained 102−104. The dielectric behavior was consistent with the conductive behavior, and the appearance of the high ε values was caused by polarization of carrier electrons of the TCNQ salts in the conductive paths isolated or interrupted by the PPO segments. As the Wf value increased, the ε values of the TCNQ salts decreased. The decrease in the number of these paths accompanied by the increase in the Wf value led to reduced ε values.
Effect of pressure on free‐radical copolymerization kinetics. III. An improved method of measuring monomer reactivity ratios under high‐pressure conditions
Authors: Schrijver J. , Ammerdorffer J. L. , German A. L. 
Published: April 2003

AbstractTo investigate high‐pressure copolymerizations a sampling technique has been developed enabling continual on‐line GLC analysis of the reaction mixture. As a result more reliable kinetic data are obtained. This new “sequential sampling” method, allowing the use of gaseous monomers, has been tested for the copolymerization of ethylene with vinyl propionate at 118 MPa and 335 K with tert‐butyl alcohol as solvent. The results are compared with those obtained with the “quenching” method used so far, which yields compositional data on the reaction mixture before and after the high‐pressure stage, only. It is shown that the “sequential sampling” method is the most adequate method of determining high‐pressure monomer reactivity ratios. Furthermore, it is an important safety feature that the present procedure can be easily remote controlled. The present experimental method is neither restricted to copolymerization nor to gas‐chromatographic analysis of the reaction mixture.
Dispersion photopolymerization of styrene
Authors: Mayoral Joaquin F. , Levy Moshe 
Published: April 2003

AbstractPhotopolymerization of styrene was carried out in a dispersed system to obtain 10 μm particles, using d‐t‐butylperoxide as initiator and poly(vinyl alcohol) as protective colloid. It was shown that particles typical for latex polymerization are also formed and interfere with the dispersion polymerization when excess protective colloid is used.
Charge transfer interaction and electrical conductivity of poly(vinyl acetals) containing dispersed TCNQ radical anion salts
Authors: Kim O.‐K. , Fox R. B. 
Published: April 2003

AbstractCharge transfer (CT) interaction is described in semiconducting dispersions of TCNQ complex salt \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Et}_3 {\rm NH}^+ ({\rm TCNQ})_2^{\cdot^{\hskip-3.7pt\hbox{--}}}$\end{document} with and without added TCNQ°, in poly(vinyl acetal) matrices in which the electron‐donor moiety is varied. The extent of CT interaction was determined in films and in solution (DMF, acetonitrile, or methylene chloride) through the absorbances at 398 nm (\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm TCNQ}{\ }^{\cdot^{\hskip-3.7pt\hbox{--}}}$\end{document} and TCNQ°) and 857 nm \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm TCNQ}{\ }^{\cdot^{\hskip-3.7pt\hbox{--}}}$\end{document}. Resistivity of the conductive films was related to the stoichiometry of TCNQ species in the films and found to have a minimum at \documentclass{article}\pagestyle{empty}\begin{document}$[{\rm TCNQ}^\circ]/[{\rm TCNQ}{\ }^{\cdot^{\hskip-3.7pt\hbox{--}}}]\simeq 1$\end{document}. Lower resistivities were attained with films having a uniform, densely packed dispersion of microcrystallites which were obtained at a relatively slow solvent removal rate. With this particular complex salt, strong electron‐donor polymers are found to be better matrices for semiconductivity.
Poly[(2‐chloroethyl)oxirane], poly[(3‐chloropropyl)‐oxirane] and poly[(4‐chlorobutyl)oxirane]: New polyether elastomers of improved chemical reactivity
Authors: Shih J. S. , Brandt J. F. , Zussman M. P. , Tirrell D. A. 
Published: April 2003

Abstract(2‐Chloroethyl)oxirane, (3‐chloropropyl)oxirane, and (4‐chlorobutyl)oxirane were prepared from the corresponding alkenols and polymerized using a triethylaluminum‐water‐acetylacetone initiator system. Copolymerizations with propylene oxide and epichlorohydrin were also accomplished; the copolymerization activities of the (chloroalkyl)oxiranes were similar to the activity of epichlorohydrin. Poly[(2‐chloroethyl)oxirane], poly[(3‐chloropropyl)oxirane], and poly[(4‐chlorobutyl)oxirane] exhibit elastomeric properties and are highly reactive in nucleophilic substitution reactions.
Ground‐state dynamics of α‐methylstyrene. I. Thermally induced oligomerization in bulk
Authors: Kauffmann H. F. , Harms H. , Olaj O. F. 
Published: April 2003

Abstractα‐Methylstyrene (α‐Me‐St) in bulk undergoes a variety of thermally induced processes which we investigated in detail by product‐distribution analysis. The oligomeric products, shown by GC–MS coupling techniques and independent syntheses, consisted of nine dimers and nine trimers with no detectable higher oligomers or polymers. Two isomeric cyclobutanes and one of the open‐chain unsaturated dimers were formed by a conventional two‐step cycloaddition; a Flory‐type diradical was the common intermediate. In contrast to these 2π + 2π products, the majority of the remaining oligomers could not be interpreted on the basis of π‐electron interaction between closed shell molecules. Their structures, however, were compatible with a free radical process in which cumyl(MH·) and 1,4‐dimethyl‐1‐phenyl‐tetrahydronaphthalene‐yl(THN·), which are consecutive products of 4π + 2π and 2π + 2π interactions, respectively, were involved in addition and transfer reactions. Because of the small rate of initiation and the obvious lack of free radical recombination products, a mechanism was suggested in which MH· and THN· radicals react predominantly in a closed sequence of elementary processes and to a rather small extent only by bimolecular free radical termination. Two sorts of stabilization steps, hydrogen transfer to monomer (RnH· + M → Rn + MH·) and hydrogen abstraction from a hypothetical 4π + 2π intermediate I (RnH· + I → RnH2 + THN·), are attributed to the high rates of unsaturated and saturated oligomer formation.
The effect of the purity of ingredients, oxygen, and inorganic particulate dispersion on the course of styrene emulsion polymerization
Authors: Hasan Syed Mahmud 
Published: April 2003

AbstractA study of the effects of ingredients on styrene emulsion polymerization kinetics showed that the purity of sodium dodecyl sulfate emulsifier affected the rate of polymerization (Rp) in the absence of added initiator. Below a critical concentration oxygen accelerated the Rp; above the critical concentration it inhibited the Rp. The effect of distilling styrene, compared to washing it with alkali to deinhibit, was minimal. Indications are that particulate dispersions of silica and titanium dioxide are encapsulated in situ by the growing polymer chains during styrene emulsion polymerization.
Mechanism of styrene emulsion polymerization during interval II
Authors: Hasan Syed Mahmud 
Published: April 2003

AbstractA systematic study of the kinetics of styrene emulsion polymerization in the postnucleation stage by the way of seed particle growth of monodisperse latices was undertaken, in which the colloidally important parameters were varied: Rp was independent (within limits) of (a) ionic strength, (b) pH, (c) initiator concentration (potassium persulfate), and (d) surfactant (sodium dodecyl sulfate) concentration; Rpp was independent (within limits) of (a) seed particle number concentration N, (b) oil:water phase ratio, and (c) monomer:polymer ratio; Rp was directly proportional to seed‐particle surface area. The viscosity average molecular weight of the polymer formed during interval II, Mv(i–j), was approximately constant and increased linearly with N. Log Mv(i–j) was inversely proportional to reaction temperature; Mv(i–j) was inversely proportional to initiator concentration. The overall activation energy of polymerization E′p was equal to the activation energy of propagation Ep during interval II. The value of kp at 60°C was 615 dm3 mol−1 s−1. Trace of oxygen seems to affect the average number of radicals per particle ī during interval II polymerization.
Polymers containing hydrogen bonding rings. Synthesis and thermal properties of poly(enamine‐ketones)
Authors: Pavlisko J. A. , Huang S. J. , Benicewicz B. C. 
Published: April 2003

AbstractThe synthetic route to poly(enamine‐ketones) by vinylogous nucleophilic substitution of aromatic bis(1,3‐diketones) with aromatic and aliphatic diamines is described. The preparation of aromatic bis(1,3‐diketones), their polymerization, and thermal properties of the polymers are presented in detail. The polymers exhibited anisotropic melts and representative model compounds were shown to be thermotropic liquid crystals.