bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of oriented monomers. IX. Further studies on the polymerization and vesicular properties of allyl and diallyl based monomeric and polymerized quaternary ammonium salts
Authors: Babilis D. , Paleos C. M. , Dais Photis 
Published: April 2003

AbstractThe polymerization of the previously reported allyl and diallyl quaternary ammonium salts, which from vesicles in water, to their polymerized analogs was further investigated. The structure of the polymer derived from the diallyl derivative, for which some controversy existed, was elucidated by 13C‐NMR spectroscopy. Mixed vesicles, based on the monoallyl monomer and incorporating certain vesicle forming quaternary ammonium salts, cholesterol, or cholesteryl acrylate were also formed. These mixed vesicles were characterized primarily as far as their stability is concerned. It was found that the incorporation of the additives does not enhance the stability of the mixed vesicles compared to that exhibited by monoallyl simple vesicles. In addition, polymerization of mixed monoallyl‐cholesteryl acrylate vesicles results in the destruction of their structure. On the contrary, simple polymerized vesicles, resulting from the diallyl monomer, showed excellent long‐term stability. Specifically, samples prepared two years ago are still dispersed and, very possibly, they will remain so for a longer period since they are not showing signs of precipitation.
Investigation of the formation of poly(ethylene terephthalate) with model molecules: Kinetics and mechanisms of the catalytic esterification and alcoholysis reactions. II. Catalysis by metallic derivatives (monofunctional reactants)
Authors: Otton Jean , Ratton Serge , Vasnev Valerii A. , Markova Gali D. , Nametov Kahirman M. , Bakhmutov Vladimir I. , Komarova Lidiy I. , Vinogradova Svetlana V. , Korshak Vasilii V. 
Published: April 2003

AbstractThe reactions of model molecules were considered to study the kinetics and the mechanism of the esterification and the alcoholysis reactions catalyzed by various metal compounds (Li, Na, K, Zn, Co, Mn, Ti). Ti was found to be the most active catalyst for both reactions and to be acting via a different mechanism (concerted). The possible structure of the active titanium intermediate was investigated by means of 1H‐ and 13C‐NMR spectroscopy, FT–IR spectroscopy, and electroconductivity.
Preparation and properties of aromatic–aliphatic copolyamides from aromatic diisocyanates and dicarboxylic acids
Authors: Otsuki Toshihiro , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractAromatic–aliphatic random copolyamides of high molecular weights were prepared by the high‐temperature solution polycondensation from a combination of aromatic diisocyanates, 4,4′‐methylenedi(phenyl isocyanate), and 2,4‐tolylene diisocyanate, and a mixture of isophthalic acid and aliphatic dicarboxylic acids with 4–10 methylene groups. Reaction conditions, such as solvent, temperature, time, and catalyst were studied to determine the optimum conditions for the preparation of high molecular weight polymers. Glass transition temperatures of the copolyamides were in the range of 131–244°C and varied with combination and composition of the diisocyanates and dicarboxylic acids used. The copolyamides prepared from 2,4‐tolylene diisocyanate had greater solubility and higher glass transition temperatures than those obtained from 4,4′‐methylenedi(phenyl isocyanate).
Synthesis, free‐radical polymerization, and stereochemical configuration of methyl α‐p‐cyanobenzylacrylate
Authors: Madruga E. L. , Román J. San , Alcalde J. , Fernandez‐Monreal M. C. 
Published: April 2003

AbstractMethyl α‐p‐cyanobenzylacrylate was synthesized from dimethyl malonate following well‐known organic reactions. The purified monomer was polymerized by a free‐radical mechanism in benzene solution, using AIBN as initiator in the interval 50–90°C. The kinetic results seem to indicate an apparent ceiling temperature near 90°C. The analysis by 13C‐NMR of polymers obtained indicates that the macromolecular chains are predominantly syndiotactic and the tacticity is independent of the polymerization temperature in the experimental interval studied. However, the determination of conditional probabilities for iso‐ and syndiotactic additions and the persistence ratios indicate that the propagation mechanism for the radical polymerization of methyl α‐p‐cyanobenzylacrylate does not follow a typical Bernoullian statistics.
Emulsion polymerizations. II. Kinetics, molecular weight distributions, and polymer microstructure of emulsion copolymers
Authors: Giannetti Enzo , Storti Giuseppe , Morbidelli Massimo 
Published: April 2003

AbstractThe kinetics of emulsion copolymerizing systems during intervals II and III (i.e., after completion of latex particle formation) has been studied through the pseudo‐homopolymerization approach. The Smith–Ewart equations for copolymers are reduced to the corresponding equations for homopolymers by introducing suitable pseudo‐homopolymerization parameters. Analogies and differences between our results and those of previously reported treatment are critically discussed. On the grounds of the probabilistic approach developed in Part I of this series, a detailed description of the copolymer chain structure is derived for systems containing no more than one growing radical per particle. In particular explicit algebraic relationships are reported for both the two‐dimensional molecular weight distribution and the unidimensional marginal distribution functions of molecular weight and chemical composition. A complete description of the chain microstructure is also reported. Equations are derived specifying the time evolution of the monomer sequence distribution and polymer end groups.
Perfume alcohols supported to sulfochlorinated poly(styrene‐co‐divinyl benzene) beads
Authors: Galioǧlu Oya , Akar Ahmet 
Published: April 2003

AbstractPerfume alcohols such as 2‐phenyl ethanol and eugenol were supported to sulfochlorinated poly(styrene‐co‐divinyl benzene) beads in the presence of base such as triethyl amine, pyridine, and sodium bicarbonate and their hydrolysis at different temperature was studied.
Metallocene–methylaluminoxane catalyst for olefin polymerization. II. Bis‐η5‐(neomenthyl cyclopentadienyl)zirconium dichloride
Authors: Chien James C. W. , Razavi Abbas 
Published: April 2003

AbstractBis(neomenthyl cyclopentadienyl)zirconium dichloride/methyl aluminoxane (η5‐(NMCp)2ZrCl2/MAO) catalyst has been investigated for ethylene polymerization. About 51% of the Zr forms active sites more or less instantaneously according to quenching with tritiated methanol. There is an initial drop of rate of polymerization, Rp, of about 30% which remains constant thereafter. The catalytic activity increases monotonically with temperature; it is proportional to [MAO]1.75 at a constant [Zr] = 1.5 μM and proportional to [Zr]−1.2 at a constant [MAO] = 64.5 mM. At very large [MAO]/[Zr], the catalyst has extremely high activity; κp = 5 × 103 (Ms)−1 at 50°C. There is also facile chain transfer to aluminum, κ = 0.14 s−1 at 50°C. Both κp and κ are about 30 times greater than the corresponding rate constants for MgCl2 supported TiCl3 catalysts. The TiCl3/MgCl2 and (NMCp)2/MAO catalysts have nearly the same activation energy for propagation (ca. 7 kcal/mol−1). The higher activity of the latter is due to its larger preexponential factor in κp. The dependence of catalytic activity on the [MAO]/[Zr] ratio may be explained by rapid association‐dissociation equilibria of MAO involving acid‐base and/or electron deficient bridge complexation.
Reactivities of methacrylate derivatives in radical polymerization as evaluated by mercury method
Authors: Ueda Mitsuru , Mano Motokazu , Ito Hiroshi 
Published: April 2003

AbstractReactivities of methyl methacrylate derivatives bearing substituents on the ester methyl group have been investigated by competitively adding a cyclohexyl radical generated by a reaction of cyclohexylmercuric chloride with sodium borohydride (mercury method) to these substituted methacrylates and methyl methacrylate or styrene. The relative rate constants of the cyclohexyl radical addition have been found to be nicely correlated with parameters such as Traft α* constants of alkyl esters, Q–e values, lowest unoccupied molecular orbital energies, β‐carbon chemical shifts, and relative reactivities toward a polystyryl radical, indicating that the mercury method is a simple and useful technique for evaluation of the relationship between structure and reactivity of vinyl monomers in their radical polymerization, even when the structural modification is small.
Thermotropic copolyesters. III. Synthesis and characterization of liquid crystal copolyesters containing the bicyclo[2.2.2]octane ring system
Authors: Polk Malcolm B. , Banks Harold D. , Onwumere Fidelis , Venkatasubramanian N. , Nandu Mahendra , Phingbodhipakkiya Metha , Samulski Edward T. 
Published: April 2003

AbstractA number of thermotropic copolyesters which contain the bicylo[2.2.2]octane ring system have been synthesized. Because of the stiffening effect of the bicyclo[2.2.2]octane group on the chain, the sebacoyl spacer was used to obtain meltable compositions.
The effect of divinylsulfone on the irradiation crosslinking of polypropylene
Authors: Sasaki Yusuke , Imai Masahiko , Tanaka Jun , Shimizu Harumichi 
Published: April 2003

AbstractPolypropylene films were irradiated with 60Co γ‐rays in divinylsulfone (DVS) or butadiene (BD) gases. The variations of the intrinsic viscosities of the samples irradiated in vacuum or in DVS with dose showed usual patterns but the variation of the latter was somewhat more rapid. The intrinsic viscosity of the sample irradiated in BD could not be measured due to the early appearance of gel. The gel fraction of the sample irradiated in DVS appeared at lower dose than that irradiated in vacuum, but the former did not increase as much as the latter. The gel fraction of the sample irradiated in BD increased remarkably. The concentrations of the two kinds of double bonds increased in the sample irradiated in BD but levelled off gradually with dose. ESR study showed that the polypropylene radical reacted with DVS to form anisotropic radicals. The mechanisms of the effects of both reagents on irradiation of polypropylene were discussed.
Control of composition in ethylene copolymerizations using magnesium chloride supported Ziegler–Natta catalysts
Authors: Mulhaupt Rolf , Ovenall Derick W. , Ittel Steven D. 
Published: April 2003

AbstractIncorporation of a sterically hindered phenol (2,6‐di‐tert‐butyl‐4‐methylphenol) during the preparation of MgCl2‐supported titanium catalysts coupled with the use of an aluminum alkyl activator modified with the same phenol and an electron donor such as ethyl benzoate allows the systematic modification of the reactivity ratios of ethylene and 1‐olefin copolymerizations. The polymers obtained tend to be largely random with a tendency toward alternating at high comonomer incorporation. Very low density LLDPE copolymers have been prepared in stable slurry polymerizations. The same catalysts allow the preparation of copolymers with dienes.
A new approach to high temperature photoresists based on styrylpyridinium units
Authors: Li Min Yu , Pearce Eli M. , Reiser A. , Narang S. 
Published: April 2003

AbstractFour linear polyesters containing styrylpyridinium units were prepared from 2,6‐bis(p‐hydroxystyryl)pyridine and terephthalic acid, isophthalic acid, adipic acid, and sebacic acid, respectively. The polyesters are thermally stable in the 365 to 450°C range. The decomposition temperature is higher for aromatic polyesters, lower for their aliphatic analogs. The polyesters are photoreactive and crosslink on irradiation with UV. The crosslinking mechanism is 2 + 2 cycloaddition. The polyesters form protonated complexes with CF3COOH which absorb at longer wavelengths and are also photoreactive. The quantum yield of the photoreaction and the relative photosensitivities of the polyesters and their complexes were determined.
Pseudoheterogeneous polymerization of methyl methacrylate in presence of some metal chlorides or sulfates
Authors: Badran A. S. , Helaly F. M. , Younan A. F. 
Published: April 2003

AbstractThe aqueous pseudoheterogeneous polymerization of methyl methacrylate in the absence and presence of some metal chlorides or sulfates was carried out in nitrogen atmosphere at 40°C using sodium bisulfite as initiator. The metal chlorides or sulfates were found to catalyze the rate of polymerization of methyl methacrylate to different extents. The highest effect was obtained in the presence of copper salts, a moderate effect was obtained when iron salts were used, and the least effect was caused by the others. All 13C‐NMR spectra for the polymers obtained in the absence and presence of some metal salts were those to be expected for radically initiated poly(methyl methacrylate)s of conventional, slightly syndiotactic‐rich microstructures prepared at normal temperature. The spectra were found to be very similar to that for a radical poly(methyl methacrylate) first analyzed by Inoue et al. The ratios of isotactic (mm): heterotactic (mr,rm): syndiotactic (rr) triads were found to be close to 6 : 32 : 62. The polydispersity for some poly(methyl methacrylate)s determined by gel permeation chromatography technique was found here to vary rather widely and ranges between 1.8 and 8.92.
Crosslinking of polystyrene under friedel–crafts conditions in dichloroethane and carbon tetrachloride solvents through the formation of strongly colored polymer–AlCl3–solvent complexes
Authors: Rabek Jan F. , Lucki Julia 
Published: April 2003

AbstractPolystyrene was crosslinked in either 1,2‐dichloroethane or carbon tetrachloride in the presence of aluminum chloride. Apparently, the reactions involve Friedel–Crafts substitution of phenyl ring with CH2CH2Cl or CCl3 groups, which than participate in crosslinking, giving CH2CH2 or CCl2, CCl, and C bridges. In the first stage a charge‐transfer complex is formed between AlCl3, polystyrene and the solvent. After heating this complex above 35–40°C a rapid formation of HCl occurs and a crosslinked polymer is formed. This final product is insoluble, infusible, and inflammable. It decomposes at 400°C without melting.
Synthesis of organotin polymers by the reaction of diallyl carbonates with Bu3SNH
Authors: Moriya Osamu , Arai Seiji , Endo Takeshi 
Published: April 2003

AbstractTri‐n‐butyltin hydride (Bu3SnH) was employed for the synthesis of organotin polymers via radical process. The polymers having both organotin and carbonate groups were obtained by the reaction of Bu3SnH with monomers such as diallylcarbonate and diethylene glycol bis(allyl carbonate) via hydrostannation. The copolymerization of diethylene glycol bis(allyl carbonate) and the mono‐hydrostannated derivative was also conducted to obtain the corresponding polymers.
Poly(phenylene sulfide): Synthesis from 1,4‐dibromobenzene and sodium sulfide
Authors: Rajan C. R. , Nadkarni V. M. , Ponrathnam S. 
Published: April 2003

AbstractA new route to synthesize poly(p‐phenylene sulfide) by nucleophilic substitution of 1,4‐dibromobenzene with sodium sulfide in N‐methylpyrrolidone is described. Kinetic evaluation shows the reaction to be of second order with two distinctive rate constant regimes. The first rate constant is higher and is operative until 50% conversion, whereas in the second regime (between 50 and 92% conversion) the rate is slower. The kinetics of this route is compared under identical conditions with the conventional synthesis based on 1,4‐dichloro benzene and sodium sulfide.
Polyesters from α,α′‐dicarbomethoxy‐α,α′‐diphenyl‐p‐xylylene and the synthesis and properties of a new quinodimethane
Authors: Mulvaney J. E. , Green G. David 
Published: April 2003

AbstractA film forming polyester was obtained from the title compound and 1,4‐butanediol. In addition oxidation of the title compound gave rise to 7,8‐dicarbomethoxy‐7,8‐diphenylquinodimethane as a mixture of Z and E isomers. The 1H‐NMR and the electronic characterization of this polymer are discussed. The quinodimethane will undergo 1,6‐nucleophilic addition to form an aromatic compound.
The synthesis of poly(hydroxamic acid) from poly(acrylamide)
Authors: Domb A. J. , Cravalho E. G. , Langer R. 
Published: April 2003

AbstractPoly(hydroxamic acid) in gel or water soluble from was prepared from the reaction of poly(acrylamide) and hydroxylamine in basic aqueous solution (pH > 12) at room temperature. The polymers were composed of 70% hydroxamic acid groups, less than 5% carboxylic acid groups, and 25% unreacted amide groups. The polymers exhibited high affinity to iron(III) and copper(II) in the pH range of 1 to 5 with a high binding rate. A binding of 3 mmol/g for both metals was achieved. Preliminary tests demonstrated the urease inhibitory activity of both linear and crosslinked poly(hydroxamic acids).
Longitudinal volume viscosity of poly(methyl methacrylate)
Authors: Hurtado‐Laguna F. , Aleman J. V. 
Published: April 2003

AbstractVolume flow of poly(methyl methacrylate) (PMMA) (M̄n = 43,000 and Tg = 384) has been measured in an Instron Capillary Rheometer. Elastic modulus of the longitudinal wave, longitudinal volume viscosity, initial longitudinal volume viscosity, and retardation times are described at temperatures above Tg (418–483K) and compression rates of about 1.00–200.00 × 105 s−1. An initial increase followed by a decrease in longitudinal volume viscosity has been observed as the compression rate increases and the volume deformation decreases, this last behavior being at the lowest values of the compression rate (6.0 and 30.0 × 10−5 s−1) a typical nonequilibrium one. ηL also increases with increasing temperature (Tg decreases 0.18°C/MPa), and volume flow activation energy decreases as the volume deformation increases.
Radiolysis of polymers of chlorine methacrylates
Authors: Wuensche P. , Mueller S. , Lorkowski H.‐J. 
Published: April 2003

AbstractPolymers of α‐chloroacrylate (MCA), 1‐chloroethyl methacrylate (1CEMA), 2‐chloroethyl methacrylate (2CEMA), 2,2,2‐trichloroethyl methacrylate (trCEMA) and 1,2,2,2‐tetrachloroethyl methacrylate (teCEMA) were γ‐irradiated at 77 K. The primary radicals were generated by the abstraction of chlorine. They decay or change into chain end radicals upon warming up to room temperature.
Photoreactive polyamides having m‐ or 1‐type dimer moiety derived from 4‐(3‐oxo‐3‐phenyl‐1‐propenyl)benzoic acid derivatives
Authors: Nohara Masao , Hasegawa Masaki , Harashina Hatsuhiko , Iitaka Yoichi 
Published: April 2003

AbstractPhotoreactive polyamides having m‐ or 1‐type cyclobutane moiety were prepared via a topochemical photodimerization of 4‐(3‐oxo‐3‐phenyl‐1‐propenyl)benzoic derivatives,4 followed by polycondensation of cyclobutane dicarboxylate derivatives with diamines. From the spectral studies of resulted polyamides compared with the corresponding reference diamides, it was concluded that both types of polyamides were depolymerized photochemically to give the same type of amide derivative having chalcone moiety with a small amount of undefined side reaction. The cyclobutane ring of the m‐dimer from 4‐(3‐oxo‐3‐phenyl‐1‐propenyl)benzoic acid in crystal is severely twisted presumably because of the enhanced steric repulsions between two pairs of adjacent substituents. The higher quantum yield of the m‐dimer for the photocleavege, compared with that of the 1‐dimer, has been interpreted in terms of such steric repulsions by the strained structure of the m‐dimer.
Reaction of triphenylphosphine with poly(ethylene terephthalate) and certain model compounds at elevated temperature
Authors: Suebsaeng Thitivat , Wilkie Charles A. , Brown Charles E. 
Published: April 2003

AbstractTriphenylphosphine and poly(ethylene terephthalate) react at 370°C to produce ethylene, triphenylphosphine oxide, carbon dioxide, benzoic acid, and terephthalic acid. The reaction proceeds by the initial formation of a zwitterionic species which then generates a phosphonium ylid and leads to the observed products. Any flame retardant activity from the use of triphenyl‐phosphine may be attributed to the formation of triphenylphosphine oxide. The co‐production of ethylene renders triphenylphosphine a less effective flame retardant than triphenylphosphine oxide.
Synthesis and polymerization of 2‐butyl‐7‐methylene‐1,4,6‐trioxaspiro(4,4)nonane
Authors: Pan Cai‐Yuan , Wang Yin , Bailey William J. 
Published: April 2003

Abstract2‐Butyl‐7‐methylene‐1,4,6‐trioxaspiro(4,4)nonane (7) was prepared by the reaction of 2‐(bromomethyl)‐5‐oxo‐tetrahydrofuran with 1,2‐epoxyhexane, followed by dehydrobromination. Compound 7 could be polymerized by free radical initiators to give a viscous polymer. The IR and NMR spectra of the polymers indicated that the polymer structure contained ester and ketone units in the backbone, and a cyclic acetal side chain. Compound 7 readily copolymerized with acrylonitrile in the presence and absence of radical initiators, but did not copolymerize well with styrene. Ultraviolet spectra suggest that the spontaneous polymerization proceeds via a chargetransfer complex between 7 as an electron donor and AN as an electron acceptor.
Powder and fiber filled interpenetrating network of metal polymer composites (INMPC) of polypropylene
Authors: Semsarzadeh Mohammad Ali , Hudgin Donald E. 
Published: April 2003

AbstractThe mechanical properties of conductive powder and fiber‐filled interpenetrating network of polymer metal composites (INMPC) of polypropylene with metal alloys based on Sn, Zn, Mo, Al, Cu, Ag, and Sb are reported. New nomenclature, terminologies, and definitions are presented. New models are also discussed.
Study of the synthesis of poly(isobutylene‐b‐amide‐11) by polycondensation of α,ω‐dianhydride oligoisobutylene with α,ω‐diamino oligoamide‐11. I. Study of amine–anhydride and amide–anhydride reactions on low molecular weight models and on oligomers and polymers
Authors: Tessier Martine , Marechal Ernest 
Published: April 2003

AbstractThe side reactions connected with the polycondensation of α,ω‐diamino oligoamides and α,ω‐dianhydride oligoisobutylenes are studied on low and high molecular weight models. Models for amine and anhydride end groups are dodecylamine and (2‐dodecene‐1‐yl) succinic anhydride, respectively; their reaction is studied in the bulk (170°C) and in solution (142, 152, and 162°C); the products are analyzed by 1H‐, 13C‐, and 1H‐13C‐NMR and GPC. Some of these products and the junctions between the blocks are prepared independently. Models of amide groups in the chain are N‐dodecyldodecanamide and N‐dodecyloctadecanamide; their reaction with anhydride model results in cleavages with formation of imide groups. The results obtained from low molecular weight models are confirmed by studies on oligomers. They show unambiguous by that crosslinking which accompanies the block polycondensation originates from the reaction of amino‐end groups with the intermediary acid groups resulting from the amine‐anhydride reaction.