bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of methyl methacrylate by a charge transfer mechanism with urea and iron (III) complex
Authors: Hussain S. , Dass N. N. 
Published: April 2003

AbstractMethyl methacrylate (MMA) can be polymerized by a charge transfer complex formed by the interaction of urea, methyl methacrylate, and carbon tetrachloride (CCl4) in a nonaqueous solvent like dimethylsulfoxide (DMSO). The rate of polymerization can be accelerated by Lewis acids like Fe3+. This article reports the polymerization of MMA initiated by urea and CCl4 and accelerated with hexakisdimethylsulfoxide iron (III) perchlorate, [Fe(DMSO)6](ClO4)3, and A at 60°C. Definite induction periods were observed for the polymerization reaction initiated by urea and CCl4 alone, but the induction period completely vanished when the molar ratio of urea to A reached 6:1. The molecular weights of the polymers with 6:1 molar ratio of urea to A were higher than with urea alone. The rate constant for the polymerization of MMA in the presence of [Fe(urea)6]3+ was 1.03 × 10−5 1 mol−1 s−1 at 60°C. The transfer constant for CCl4 for polymerization with urea alone is 2.43 × 10−3 at 60°C.
Dehydrochlorination of poly(vinyl chloride) by aqueous sodium hydroxide solution under two‐phase conditions
Authors: Kise Hideo 
Published: April 2003

AbstractThe reaction of poly(vinyl chloride) powder with aqueous sodium hydroxide solution in the presence of quaternary ammonium or phosphonium halides yielded dehydrochlorinated products of conjugated polyene structure. The reaction was discussed in terms of a phase transfer catalytic mechanism between aqueous and polymer phases. Among the catalysts used tetrabutylammonium bromide was the best. To obtain the optimum conditions the effects of reaction temperature, the concentration of NaOH and the catalyst, and the molecular weight of poly(vinyl chloride) were investigated. Treatment of PVC films and solutions in tetrahydrofuran with aqueous NaOH solutions under two‐phase conditions also produced dehydrochlorinated films and powders.
Reaction rate of crosslinkings by using a metallated polymer. III. Solvent effects on rate constants of grafting and intramolecular crosslinking reactions.
Authors: Ishizu Koji , Ohtaka Atsushi , Fukutomi Takashi , Kakurai Toshio 
Published: April 2003

AbstractLithium‐metallated (styrene‐p‐benzylstyrene)copolymer was reacted with chlorine‐terminated polystyrene as a crosslinker polymer in a mixture of tetrahydrofuran (THF)–n‐hexane at 25°C in the presence of lithium chloride(LiCl). The rate constants were estimated from the changes in the concentration of metallated polymer by photometrical measurements. As a result, the rate constant of grafting (k1) showed a constant value in spite of a change in molecular weight of the crosslinker polymers and the addition of n‐hexane. The rate constant of intramolecular crosslinkings (k2intra) obtained in a mixed solvent (21 ∼ 36 vol % of n‐hexane) increased when the molecular weight of the crosslinker polymers and the extent of n‐hexane were increased.
Polymerization of allyl esters of unsaturated acids. IX. Controlled ring closure in the radical cyclopolymerization of allyl methacrylate
Authors: Matsumoto Akira , Ishido Hirozo , Oiwa Masayoshi , Urushido Kunio 
Published: April 2003

AbstractRadical cyclopolymerization of allyl methacrylate (AMA) was investigated in detail, especially under the specified conditions; that is, above the ceiling temperature for a head‐to‐tail propagation (ΔGht ≥ 0) in the polymerization of methacrylate. Thus the structure of the polymer obtained was examined by 1H‐ and 13C‐NMR and infrared (IR) spectroscopy; no existence of unreacted pendant methacrylyl groups was observed, which suggests that, as a cyclopolymerization mechanism of AMA, intermolecular propagation of growing radicals, followed by intramolecular cyclization or intermolecular propagation of the resulting uncyclized methacrylyl radical, occurs exclusively with methacrylyl group. Temperature dependency of cyclization constant Kc was unusual; Kc increased rapidly at elevated temperatures and no linear relationship of ln Kc vs. 1/T was observed. Five‐membered ring formation was favored at an elevated temperature and diluted monomer concentration. These results are discussed thermodynamically in terms of controlled ring closure in cyclopolymerization.
Densimeter detector in gel permeation chromatography of copolymers
Authors: Elsdon W. L. , Goldwasser J. M. , Rudin A. 
Published: April 2003

AbstractA commercially available densimeter with a vibrating stainless steel tube was used as a detector in the GPC analysis of styrene/methyl methacrylate copolymers under normal GPC operational conditions. The densimeter was thermostated to ±0.001°C and sample injection concentrations were 4.0 mg/mL. The copolymer samples were polydisperse in molecular weight but uniform in composition. A refractive index detector and the densimeter detector produced comparable estimates of the parameters of the molecular weight distributions. The densimeter is less sensitive to the effects of variations in copolymer composition than differential refractive index or ultraviolet detectors. The only serious drawback to the densimeter is a relative lack of sensitivity. Variations in composition of styrene/methyl methacrylate copolymers over a fairly wide range have no signficant effect on the relation between gel permeation chromatographic elution volume and copolymer molecular weight. In general, however, conventional means of summarizing these data are not applicable to compositionally heterogeneous mixtures. Instrumental and data‐handling solutions to this problem are discussed.
Second moments of ESR signals from poly(p‐phenylene) and the deuterated analog
Authors: Kovacic Peter , Howe Russell F. , Khoury Issam 
Published: April 2003

AbstractThe second moments of the ESR signals obtained from poly(p‐phenylene) (PPP) and deuterated PPP were measured at 9.5 and 35 GHz. The theoretical and experimental contributions to the second moments were considered. It is shown that for deuterated PPP, deuteron hyperfine splitting makes a negligible contribution to the observed second moment. The proton hyperfine contributions to the second moments of the radical species in PPP and p‐sexiphenyl were estimated and it was concluded that the unpaired electron was delocalized over only 2‐4 phenylene units. A rationale is offered in terms of polarons present as defects in the PPP chains.
Functional monomers and polymers. CII. Synthesis and properties of oligomer models of polyethyleneimine derivatives containing pendant adenine bases
Authors: Sakuma Yo , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractA series of oligomer model compounds of polyethyleneimine derivatives with pendant adenine bases were prepared by the reaction of a carboxyethyl derivative of adenine with oligomeric amines, using an activated ester method. To evaluate the intramolecular interaction between pendant adenine bases in these compounds, ultraviolet spectra at various pH regions were measured. Ultraviolet hypochromicities and pKa values depended linearly on the chain length of the oligomers. The results showed that the intramolecular interactions of adenine bases were realized less in their protonated than neutral forms.
Poly(secondary amine)s from diacrylates and diamines
Authors: Shchori Ehud 
Published: April 2003

AbstractPoly(secondary amine)s were prepared by the Michael‐type addition of diacrylates or bisacrylamides with diprimary amines carrying an α or β branching to the amino groups. The steric hindrance due to branching rendered the primary amine monofunctional in respect to the acrylate, thus producing soluble polymers.
Frictional coefficients in polymer solutions and the applicability of scaling laws to experimental data
Authors: Elmgren Hans 
Published: April 2003

AbstractWhen defined in the conventional way, the relative frictional coefficient f/f0 of dissolved polymers is dependent on the method of determination used. Sedimentation and mutual diffusion‐light scattering give a common result, which by necessity differs from that obtained by self‐diffusion measurements. The difference is due to the neglect of the nonfree draining conditions in the polymer coils, causing an inadequate reference value f0 in the cases of sedimentation and mutual diffusion.The scaling theory is also discussed in the view of an alternative theory (1‐4). Besides its partly unrealistic theoretical basis, the scaling theory suffers from several weaknesses:(i) The significance of the reference frame of the studied motions is not analyzed.(ii) When the polymer concentration is increased, the original two‐phase system (swollen coils and bulk solvent) is transformed into a single‐phase system. The effect of this, in combination with the conventional definition of f and f0 used, is not analyzed in the scaling theory.(iii) No attention is drawn to the influence of the segment mobility on the concentration dependence of the studied hydrodynamic parameter.
Pyrolysis of unsaturated polyester resin. Quantitative aspects
Authors: Ravey M. 
Published: April 2003

AbstractThe thermal decomposition of this resin was examined by quantitative pyrolysis—gas chromatography. The decomposition does not follow the Hurd–Blunck mechanism generally obeyed by beta‐hydrogen containing esters. Instead, phthalic anhydride is extruded almost quantitatively. It is proposed that the mechanism involves the rearrangement of the phthalate CO bonds to extrude the anhydride, leaving a maleic acid—dipropylene glycol polyester chain.
Trityl salt—initiated polymerization of α‐methylstyrene
Authors: Velichkova R. , Panayotov I. M. , Doicheva J. , Manolova N. 
Published: April 2003

AbstractThe initiation reaction of the polymerization of α‐methylstyrene by trityl tetrachloroferate and tritylhexachloroantimonate in 1,2‐dichloroethane at 20°C was studied. The rate constants were 14 × 10−3 and 27 × 10−3 L mol−1s−1, respectively. The dissociation constants of tritylterachloroferate (Kd = 0.88 × 10−4M−1) and tritylhexachloroantimonate (Kd = 2.64 × 10−4M−1) was determined. The effect of electron acceptors and donors on the dissociation equilibrium and initiation rate was investigated. It was shown that in strongly dissociated ion pairs such as stable carbenium salts the electron donors and acceptors have no appreciable effect on the magnitude of the dissociation. The temperature dependence of the rate constants in the −20–+20°C range yielded the following thermodynamic parameters for trityltetrachloroferate: Ei = 8.54 kcal/mol; A = 3.2 × 104 mol−1s−1; ΔH* = 8 kcal/mol; and S* = −39.8 eu.
Polymerization of acrylonitrile initiated by KO2‐ nitrobenzene
Authors: Han Yang Kyoo , Jin Moon Young , Choi Sam Kwon 
Published: April 2003

AbstractPolymerization of acrylonitrile initiated by a potassium superoxide (KO2)‐nitrobenzene system was carried out in anhydrous dimethylsulfoxide (DMSO) at 25°C. The initial rate of polymerization was rapid and a high‐molecular‐weight polymer was obtained. The molecular weight was proportional to monomer concentration and inversely to concentration of initiator within 5 min. The overall activation energy was estimated as −2.6kcal/mol deg in the temperature range of 20–50°C. In addition to nitrobenzene anion radical, other anion radicals generated by one‐electron transfer from KO2 to charge transfer agents such as m‐dinitrobenzene benzoquinone, benzophenone, and naphthalene were effective in the polymerization of acrylonitrile. It is proposed that polymerization proceeds via an anionic mechanism that involves one‐electron transfer from anion radicals to monomer.
Determination of reaction variables for the starch xanthide encapsulation of pesticides
Authors: Wing R. E. , Otey F. H. 
Published: April 2003

AbstractOptimization of reaction variables such as xanthation and oxidation conditions was determined for the encapsulation of EPTC (S‐ethyl dipropylthiocarbamate) and butylate (S‐ethyl diisobutylthiocarbamate) in a crosslinked starch xanthide matrix. Sonification of EPTC and butylate emulsifiable concentrates before encapsulation decreased the size of the cells within the matrix and increased pesticide retention. Pesticide release from the matrix as determined using a constant temperature‐humidity chamber showed that low‐xanthation and sonified encapsulated products gave the slowest pesticide release.
Thermoxidative degradation of vinyl alcohol/vinyl acetate copolymers. IV. Statistical copolymers
Authors: Vasile Cornelia , Paţachia Silvia Florica , Dumitraşcu V. 
Published: April 2003

AbstractThe thermoxidative degradation of vinyl acetate/vinyl alcohol statistical copolymers was studied under dynamic thermal conditions and compared with that of block copolymers. The dependence of thermal characteristics or kinetic parameters on the content of OH groups of copolymers was established.
Synthesis and polymerization of 8,9‐benzo‐2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (BMTN)
Authors: Han Yang Kyoo , Choi Sam Kwon 
Published: April 2003

Abstract8,9‐Benzo‐2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (BMTN) was prepared by the reaction of phthalide with epichlorohydrin, followed by dehydrochlorination. BMTN was polymerized with di‐t‐butyl peroxide (DTBP) to give a solyble polymer with a high molecular weight and good thermal stability. The infrared (IR) and nuclear magnetic resonance (NMR) spectra indicated that the polymer structure contained aromatic ester and ketone in the backbone. Tg and Tm of homopolymer of BMTN were, respectively, 98 and 282°C. BMTN was also readily copolymerized with such vinyl monomers as methyl methacrylate (MMA), acrylonitrile (AN), and maleic anhydride (MA), but not with styrene, in the presence of radical initiators. AN and MA, in particular, were spontaneously copolymerized with BMTN in the absence of radical initiators at 40°C. From the results of ultra violet (UV) spectra it is suggested that spontaneous copolymerization proceeds via a charge‐transfer complex between BMTN as an electron donor and AN or MA as an acceptor.
Quantitative DSC evaluation of phase segregation rate in linear segmented polyurethanes and polyurethaneureas
Authors: Camberlin Yves , Pascault Jean Pierre 
Published: April 2003

AbstractLinearly segmented polyurethanes and polyurethaneureas are known to be phase separated; one phase is the soft phase, the other, the hard domain. Quantitative evaluation of the degree of phase separation was obtained by DSC. An estimation of the dispersed soft segments outside the soft phase can be made by ΔCp measurements and the increase in glass transition (Tg) can be attributed to the presence of hard blocks in the soft phase. The segregation rate depends on the nature of the soft segments which decrease from hydrogenated polybutadiene to polybutadiene to polyether. It also depends on the nature of the chain extender from aliphatic to aromatic diol and from aliphatic to aromatic diamine. The presence of soft segments in hard domains can be related to the thermoplastic behavior of the polyurethanes and polyurethaneureas.
Binding of methyl orange and its homologs by polyion complexes consisting of a piperidinium cationic polymer and various polyanions in aqueous solution
Authors: Takagishi Toru , Kozuka Hiroshi , Kuroki Nobuhiko 
Published: April 2003

AbstractA study was made of the formation of polyion complexes between a piperidinium cationic polymer and polyanions and of the binding of azo‐dye anions (methyl, ethyl, propyl, and butyl orange) by these complexes. Sodium poly(acrylate), poly(styrenesulfonate), dextran sulfate, and carboxy‐methylcellulose were used as polyanions. The resultant polyion complexes (insoluble in aqueous solutions) were compared for their ability to bind the small organic molecules in aqueous solutions, for example, of urea and an inorganic electrolyte (KCI), and exhibited a strong binding affinity toward these small anions. Polyion complexes that consisted of sodium poly(acrylate), dextran sulfate, and carboxymethylcellulose as polyanions cooperated in the binding, whereas the polyion complex of sodium poly(styrenesulfonate) did not. It was suggested that small organic anions interact with the polyion complexes primarily through electrostatic and hydrophobic forces.
Oligomers from biphenyl, biphenyl‐d10, or p‐terphenyl with aluminium chloride‐cupric chloride: Mechanism, ESR, and conductivity
Authors: Hsing Chih‐Fen , Kovacic Peter , Khoury Issam A. 
Published: April 2003

AbstractBiphenyl and biphenyl‐d10 were coupled by aluminum chloride‐cupric chloride. For the two systems, the yields of p‐quaterphenyl, p‐sexiphenyl, and sublimation residue were compared. The results, which have mechanistic significance, are similar to those reported earlier for benzene versus benzene‐d6; that is, a decrease in DP for the deuterated substrate. p‐Sexiphenyl, obtained from biphenyl or p‐terphenyl and aluminum chloride‐cupric chloride, displayed a concentration of 3 × 1017 spins/g in ESR. There was little or no change in spin density after sublimation or crystallization. Even after drastic purification by a variety of techniques the radical character persisted. Biphenyl was polymerized by aluminum chloride‐cupric chloride at temperatures in the 50–155°C range. Processable polymers with m‐ and p‐phenylene linkages were produced. When doped with AsF5, the highest conductivity obtained was 7.3 × 10−2 Ω−1 cm−1.
Photocrosslinking of poly(2,3‐epithiopropyl methacrylate) film with 254 nm irradiation
Authors: Egawa Hiroaki , Ishikawa Masataka , Tsunooka Masahiro , Ueda Toshihiro , Tanaka Makoto 
Published: April 2003

AbstractPoly(2,3‐epithiopropyl methacrylate) (PETMA) has an absorption maximum at 258 nm (εmax = 50) in dioxane which is due to episulfide groups. When irradiated at 254 nm under atmospheric pressure its film became insoluble. When kept at 70°C for several minutes a PETMA film became partially insoluble; however, the contribution of this thermal reaction to the photocrosslinking at room temperature was negligible. For photoreaction at 254 nm under nitrogen a low probability of main‐chain scission was ascertained by the use of the Charlesby‐Pinner equation. The IR spectrum of irradiated PETMA showed a decrease in episulfide groups and the formation of mercapto groups, which suggested that the photocrosslinking of PETMA results from free radicals formed by the cleavage of CS bonds. Free radicals in the irradiated PETMA were detected by ESR spectroscopy and the assignment is discussed. In this photocrosslinking process oxygen was a retarder at the early stage but an accelerator at the later stage.
Styrene emulsion polymerization: Kinetics and particle size distributions in highly swollen latex systems
Authors: Wood David F. , Whang Barry C. Y. , Napper Donald H. , Gilbert Robert G. , Lichti Gottfried 
Published: April 2003

AbstractThe results are reported of studies on the kinetics and the time evolution of the particle size distribution in seeded styrene emulsion polymerization systems wherein the seed latex particles were highly swollen with monomer as a result of prior swelling by dodecane. Conditions were such that no new latex particles were formed nor was a significant number of monomer droplets present (“Interval III”). The data were fitted to obtain values for the rate coefficients for entry and exit (desorption) of free radicals. It was found that, during the early part of the polymerization (when the polymer:monomer ratio in the latex particles is considerably less then in an equivalent emulsion polymerization system without dodecane), the entry rate coefficient was much smaller than that measured in systems without dodecane. This effect is consistent with an entry mechanism wherein entering free radicals must displace surfactant molecules from the latex particles.
Processable heat‐resistant polymers. XI. Synthesis and characterization of unsaturated polyamideimides
Authors: Maiti Sukumar , Ray Atanu 
Published: April 2003

AbstractPolycondensation of the diacid chloride of 2‐(3‐carboxy vinyl)phenyl‐1,3‐dioxoisoindoline‐5‐carboxylic acid with m‐phenylenediamine and the diacid chloride of 2‐(4‐carboxy phenyl)‐1,3‐dioxoisoindoline‐5‐carboxylic acid with 1,5‐bis(3‐aminophenyl)1,4‐pentadien‐3‐one was carried out in polar solvents to produce new unsaturated polyamide–imides. The solution and the thermal, electrical, and a few other properties of the polymers were studies. The polymers were soluble in highly polar solvents. The solubility parameter of the polymers was calculated from the Small's group contribution. The polymers were fairly thermostable and underwent crosslinking creaction when heated, preferably in the presence of a suitable catalyst. The crosslinked polymers were in soluble even in highly polar solvents and possessed higher thermal stability. The swelling behavior of the polymers was studied and the molecular weight between two consecutive crosslinks was determined. X‐ray diffraction and the dielectric properties of the polymers and their crosslinked products were also studied.
Redox‐initiated cationic polymerization: The diaryliodonium salt/benzoin redox couple
Authors: Crivello J. V. , Lee J. L. 
Published: April 2003

AbstractA new redox couple based on the copper‐catalyzed reduction of diaryliodonium salts with benzoins has been used to initiate cationic polymerizations of cyclic ethers and esters. A proposed mechanism for initiation by this redox couple is based on its stoichiometry and on the nature of the products. It was concluded that initiation of polymerization occurs both by direct arylation of the monomer and by protonation by strong Brønsted acids. The polymerization of several typical cationically polymerizable monomers using this new redox initiator were studied.
Polymerization of α‐methylene‐N‐methylpyrrolidone
Authors: Ueda Mitsuru , Takahashi Masami , Suzuki Toshiyuki , Imai Yoshio , Pittman Charles U. 
Published: April 2003

Abstractα‐Methylene‐N‐methylpyrrolidone (α‐MMP) was synthesized and homopolymerized by bulk and solution methods. The poly(α‐MMP) is readily soluble in water, methanol, methylene chloride, and dipolar aprotic solvents at room temperature. Thermogravimetric analysis of poly(α‐MMP) showed a 10% weight loss at 330°C in air. The kinetics of α‐MMP homopolymerization and copolymerization were investigated in acetonitrile, using azobisisobutyronitrile (AIBN) as an initiator. The rate of polymerization Rp could be expresed by Rp = k[AIBN]0.49[α‐MMP]1.3. The overall activation energy was calculated to be 84.1 kj/mol. The relative reactivity ratios of α‐MMP (M2) copolymerization with methyl methacrylate (r1 = 0.59, r2 = 0.26) in acetonitrile were obtained. Applying the Q‐e scheme led to Q = 2.18 and e = 1.77. These Q and e values are larger than those for acrylamide derivatives.
Synthesis of aminimide monomers and polymers
Authors: Mehta Avinash C. , Rickter Donald O. , Kolesinski Henry S. , Taylor Lloyd D. 
Published: April 2003

AbstractA convenient and practical synthesis of trimethylamine acrylimide, 1, starting from 1, 1, 1‐trimethylhydrazinium p‐toluenesulfonate, 3, and 3‐chloropropionyl chloride is described. The intermediate, trimethylamine 3‐chloropropionimide, 2, is easily transformed into 1 either through a single‐step dehydrohalogenation or through a two‐step process consisting of very facile thermal rearrangement to 1,1,1‐trimethylacrylylhydrazinium chloride, 4, and subsequent deprotonation. Two new polymerizable monomers, 5, and 6, containing aminimide functionality were synthesized from trimethylamine imine, 7, and the appropriate vinyl oxazolones, 8, and 9. Synthesis of hitherto unreported trimethylamine chloroacetimide, 10, which offers unique opportunities for incorporating water‐solubilizing and alkali‐stable aminimide functionality into a variety of structures through nucleophilic displacement, is also described.