bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(alkylene oxide) ionomers. VII. Use of triethylaluminum/water/acetylacetone (1.0:0.5:1.0) for the polymerization of oxiranes
Authors: Bansleben Donald A. , Hersman Marie J. , Vogl Otto 
Published: April 2003

AbstractPolymerization studies of oxiranes were conducted using a modified aluminumalkyl initiator, derived from the low‐temperature reaction by chelating agents (5°C) and hydrolysis products of triethylaluminum. The stoichiometric reaction product of acetylacetone and triethylaluminum, after partial hydrolysis with water, gave a homogeneous initiator that polymerized the oxides of ethylene, propylene, 1‐butene, 1‐hexene, 3‐chloro‐1‐propene, and 4,4,4‐trichloro‐1‐butene to the corresponding high molecular weight poly(alkylene oxides). The initiator, similar in nominal composition to the classical trialkylaluminum/water/acetylacetone (1.0/0.5/1.0) initiator developed by Vandenberg, retained a high level of activity, when properly stored, for nearly 4 weeks. The composition was inactive when the sequence of chelation and hydrolysis was reversed. Inclusion of a proton‐trapping agent in polymerization experiments of propylene oxide provided evidence that protons do not play a role in the initiation of oxirane polymerizations with modified organoaluminum oxides. Characterization of the various alkylene oxide polymers was carried out by spectroscopic, solution, and thermal techniques.
Optical rotatory dispersion and circular dichroism studies of copoly(propyl‐L‐aspartate‐benzyl‐L‐aspartate)
Authors: Tsujita Yoshiharu , Fujii Nobuaki , Imoto Yoshiko , Takizawa Akira , Kinoshita Takatoshi 
Published: April 2003

AbstractCopoly(propyl‐L‐aspartate‐benzyl‐L‐aspartate)s with various compositions were synthesized by propylation of a parent poly(β‐benzyl‐L‐Aspartate). The variation of helix sense of copolyaspartate obtained against a degree of propylation and temperature was examined by optical rotatory dispersion and circular dichroism method. Copolyaspartate of propylation less than about 70% is in a left‐handed α helix conformation and its Moffitt parameter b0 and molecular ellipticity [θ]222 decreased gradually with increasing propylation. On the other hand, a different temperature dependence of b0 and [θ]222 was observed for copolyaspartate of propylation more than about 80%, i.e., the reversible transition of the helix sense from right‐ to left‐handed α helix took place by temperature increasing. These features were basically similar to the variation in helix sense of copoly(ethyl‐L‐aspartate‐benzyl‐L‐aspartate), although a slight difference was seen for copoly(propyl‐L‐aspartate‐benzyl‐L‐aspartate). The thermodynamic treatment indicating larger entropy of right‐handed α helix suggests much mobile side chain of the right‐handed α helix than the left handed one.
Determination of carbonyl‐containing functional groups in oxidized polyethylene
Authors: Fodor Zs. , Iring M. , Tüdős F. , Kelen T. 
Published: April 2003

AbstractA combined (chemical and infrared (IR) spectrophotometric) method is discussed for the simultaneous determination of concentrations of carboxyl (A), ketone (K), and ester (E) groups formed in the oxidation of polyethylene (PE). The IR absorptivities of these functional groups were determined by using model compounds [stearic acid, stearone, poly‐(1,4‐butylene sebacate)]. The integral absorption of the CO band of polymer samples which contained several oxo groups of different types was found to be additive. This method was applied to the determination of the carboxyl, ester, and ketone content of samples oxidized at different oxygen pressures.
Catalyseurs Ziegler‐Natta supportés sur MgCl2 pour la polymérisation du propène. I. Etude de la réaction entre le triéthylaluminium et le benzoate d'ethyle
Authors: Spitz Roger , Lacombe Jean‐Loup , Primet Michel 
Published: April 2003

AbstractIn this article we describe a study of the reaction between triethylaluminium (TEA) and ethylbenzoate (BE) in a heptane solution by Fourier transform, infrared (IR), and ultraviolet (UV) spectroscopy. These compounds were chosen as a model of the cocatalytic solution used with a Ziegler‐Natta catalyst supported on MgCl2 for the stereospecific polymerization of propene. In the polymerization concentration range a 2 TEA:1 BE yellow complex was added to the solution and no free BE could be detected at a AI/BE molar ratio above 2: the solution contained only free and complexed TEA. The complex decomposed spontaneously to a colorless aluminium alcoholate. The rate of decomposition remained slow at room temperature and the reaction was enhanced by heating or by a high AI/BE ratio or high AI concentration. The decomposition was inhibited in the presence of an olefin.
Three‐component interpenetrating polymer networks (IPN's) from polyurethanes, epoxies, and poly(methacrylates)
Authors: Cassidy Edward F. , Xiao Han X. , Frisch Kurt C. , Frisch Harry L. 
Published: April 2003

AbstractThree‐component IPN systems made from polyurethanes, epoxies, and poly(methacrylates) containing charge groups in the backbones of the constituent networks have been prepared. Specific attractive forces that occurred among the various networks helped to compatibilize them and aided in the formation of true homogeneous topologically interpenetrating polymer networks. These three‐component polymer alloys, including full‐IPN's, pseudo‐IPN's, and graft‐IPN's, were characterized by means of mechanical spectroscopy, electron microscopy, and stress–strain properties. In addition, some adhesion studies were carried out (lap shear strength and peel strength). A comparison of the different types of three‐component polymer alloys showed that better properties were generally exhibited by the graft‐IPN's and full‐IPN's containing opposite charge groups.
Oscillatory reactions in polymer systems
Authors: Ishiwatari Tsutomu , Kawagishi Mitsuru , Mitsuishi Masaru 
Published: April 2003

AbstractModified Belousov–Zhabotinskii (BZ) oscillation reactions were studied in the systems of ferroin or tris(2,2′‐bipyridyl)ruthenium(II) dichloride or the polymerized ruthenium complex as electron transfer agents and sulfuric acid or polyethylenesulfonic acid (HPES) as acidic media. HPES was a good acidic medium for the chemical oscillation in spite of a long induction period. Moreover, chemical oscillation was observed at low concentration of HPES, where no oscillation was observed in the solution of sulfuric acid. On the other hand, no oscillation was observed in the solution of polystyrenesulfonic acid (HPSS). These results were discussed from the standpoint of the nature of polyelectrolytes.
Synthesis of aromatic polyesters by direct polycondensation with triphenylphosphine dichloride
Authors: Kitayama Shinichiro , Sanui Kohei , Ogata Naoya 
Published: April 2003

AbstractAromatic polyesters of high molecular weights were prepared by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids with triphenylphosphine dichloride as a new condensing agent. Reaction conditions, including the amount of reagents and the concentration of monomer, solvent, and acid acceptor, were investigated. The aromatic polyester with the solution viscosity of 1.66 dL/g was obtained from bisphenol. A and terephthalic and isophthalic acid in quantitative yield under the optimum condition. The principal advantage of this condensing agent is that, based on the recycling system, recovered triphenylphosphine oxide can be reconverted to the reactive triphenylphosphine dichloride by treating with phosgene or oxalyl chloride.
Photoinduced decomposition of the polybromostyryl carbanions
Authors: Königsberg Itzhak , Jagur‐Grodzinski Joseph 
Published: April 2003

AbstractThe photoinduced decay in THF of the sodium salt of the polybromostyryl carbanions (PSB̄) was investigated in vacuum at −78°C. Maximal rates of decay were obtained when the wavelength of the incident light corresponded to the absorption maximum of the PSB̄ at 495 nm. The quantum yield of the process was found to be 13 eq./Einstein. Products of the photostimulated decompositions at −78°C were found to be different from those obtained as result of the “dark” thermal decomposition at –20°C. Decomposition of the PSB̄ carbanions was accompanied by evolution of Br− anions and by formation of polyaryl carbanions absorbing in the 270‐ to 400‐nm range. The mechanism of the photoinduced decomposition of PSB̄, though basically analogous to the SRN1 reaction mechanism, was found to differ significantly from the latter. The intramolecular dissociative electron transfer was assumed to represent its initiation step. Its propagation was attributed to the addition of PSB̄ to the initially formed biradicals, ejection of Br− from the resulting radical anions, and intramolecular electron transfer yielding polybromostyryl radicals. Products of the photoinduced decomposition of PSB̄ remained soluble in THF when the intensity of the incident light was relatively weak, though their molecular weight distribution broadened. Insoluble, highly crosslinked polymers were obtained when the intensity of the incident light was very high.
A regenerable immobilized NADH model III. Reduction of N‐methylacridinium perchlorate by immobilized 1,4‐dihydronicotinamide
Authors: Eling B. , Hoogsteen W. , Challa G. , Pandit U. K. 
Published: April 2003

AbstractA regenerable dihydropyridine, immobilized on a macroreticular polystyrene resin, reduces the N‐methylacridinium ion. The influence of the polymeric network on this hydride transfer reaction was studied. During the reaction charge was built up in the resin and the transport of substrate was hindered, due to electrostatic repulsion. As a result, the reaction rate decreased as the reduction proceeded. It was observed that the charge accumulation was dependent on the site location. Reutilization of the polymeric reagent for the reduction of the acridinium ion amounted to 93% per cycle and was better than that observed (earlier) for the reduction of the ketone trifluroacetophenone.
Preparation and properties of photocrosslinkable poly(2‐vinyloxyethyl cinnamate)
Authors: Watanabe Shoji , Kato Masao , Kosakai Shohei 
Published: April 2003

AbstractPhotocrosslinkable poly(2‐vinyloxyethyl cinnamate)'s with substituents in para position of cinnamoyl moieties were prepared cationically. Polymerizability of the monomers was markedly governed by the substituent and the glass transition temperatures of the polymers varied in the range of about 0 to 72°C. The photocrosslinking mechanism in relation to the photosensitivity of the polymers is discussed on the basis of spectroscopical studies.
Syntheses of monomethoxy polyethyleneglycol vinyl ether macromonomers and their radical copolymerization with maleic anhydride
Authors: Suzuki Tohru , Tomono Tsugikazu 
Published: April 2003

AbstractIn order to develop new biocompatible materials, monomethoxy polyethyleneglycol vinyl ethers (Me(EG)n VE, n = 1–39) were synthesized from the corresponding monomethoxy polyethyleneglycol with acetylene. Successful purification of the macromonomers was performed by some adsorption procedures such as charcoal and ion‐exchange resin treatments. The Me(EG)n VE macromonomers were easily copolymerized with maleic anhydride (MAn) to give alternating copolymers. The copolymerization rates significantly depended on the ethyleneglycol chain length of the Me(EG)n VE, resulting in relatively lower polymerization rate of higher MW macromonomer. The use of nonelectron donor solvent such as carbon tetrachloride led to higher yields and higher MW of copolymers.
Copolymers containing alternating sequences of nucleic acid–base pairs. I. Monomer synthesis
Authors: Aponte Maria A. , Butler George B. 
Published: April 2003

AbstractTo provide suitable monomers for a study designed to synthesize copolymers containing alternating sequences of nucleic acid base pairs, the following electron‐donor monomers were synthesized: 9‐(2‐vinyloxyethyl)adenine, 1‐(2‐vinyloxyethyl)thymine, and 1‐(2‐vinyloxyethyl)‐cytosine. The following electron‐acceptor monomers were also synthesized: 9‐(2‐maleimidoethyl)adenine, 1‐(2‐maleimidoethyl)thymine, and 1‐(2‐maleimidoethyl)cytosine. The methods of synthesis are described along with their characterization by the usual methods, and their physical properties are reported. A variety of novel compounds were required as intermediates in the above identified syntheses. This paper also includes characterization of these compounds and a report of their physical properties.
The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). VI. An assessment of the relative importance of HCl‐scavenging, exchange, and addition reactions
Authors: Ayrey G. , Hsu S. Y. , Poller R. C. 
Published: April 2003

AbstractReactions of PVC with three representative stabilizers Bu2SnY2 (Y = OCOC11H23, SCH2COOCH2CH(Et)CH2CH2CH2CH3, OCOCH=CHCOOMe) in solution and under nitrogen were studied by two principal methods. First, using stabilizers with radioactive labels in the Y groups, the uptake of these groups by virgin and degraded polymer was measured. The UV‐visible absorption spectra of the stabilized polymers are discussed. Second, the effect of these three stabilizers on the rate of elimination of hydrogen chloride from heated PVC was studied. It is shown that the effects of HCI‐scavenging and of exchange reactions in suppressing the evolution of HCI can be separately evaluated. The thermal decomposition of dibutyltin bis(methyl maleate) to give maleic anhydride is reported. Interpretation of the observations is made in terms of assessing the relative importance of the various polymer–stabilizer reactions in promoting stabilization.
PVC miniemulsion polymerization. I. Origin of droplet families
Authors: Dewald R. C. , Hart L. H. , Carroll W. F. 
Published: April 2003

AbstractA soap/alcohol miniemulsion in combination with an homogenized mixture of monomer and initiator is utilized to generate PVC plastisol. Droplet distributions generated consist of two distinct types. Judicious control of soap‐to‐alcohol ratio allows control of the number and size of the smaller droplet family; homogenization and initiator water solubility affect the other. Final latex particle distribution may be unimodal or bimodal depending upon manipulation of these factors.
Electroinitiated copolymerization of indene and α‐methylstyrene
Authors: Toppare L. , Eren S. , Akbulut U. 
Published: April 2003

AbstractElectroinitiated cationic copolymerization of indene and α‐methylstyrene in dichloromethane has been investigated by constant potential electrolysis. The effects of copolymerization potential and the temperature on the copolymer composition was also studied. Constant potential electrolysis was found to be a suitable method to study the potential effects on copolymer compositions and the reactivity ratios of the monomers. The reactivity ratios were calculated according to integrated Lewis–Mayo equation.
Functionalization of polymeric organolithium compounds. Oxidation
Authors: Quirk Roderic P. , Chen Wei‐Chih 
Published: April 2003

AbstractThe oxidation of poly(styryl)lithium with molecular oxygen was investigated in the solid state (with and without N,N,N′, N′‐tetramethylethylenediamine) in benzene (with and without N,N,N′, N′‐tetramethylethylenediamine) and in benzene/tetrahydrofuran (THF) solutions. The oxidation products included the corresponding polystyrene dimer [(PS)2], the dimeric poly(styrene) peroxide (PSO2PS), poly(styrene) hydroperoxide (PSO2H), and the hydroxyl‐terminated polymer (PSOH). The hithertofore unreported macroperoxide (PSO2PS) accounts for approximately 50% of the dimeric product obtained from poly(styryl)lithium oxidations in the presence of Lewis bases. The total amount of peroxide products was determined by iodometric titration in the presence of a phase‐transfer catalyst, dicyclohexyl‐18‐crown‐6. On the basis of the effect of polar additives on the amount of dimeric products, it is concluded that dimer formation in the air termination of polymeric organolithium compounds results from oxidation and not carbonation reactions.
Salt effects in the binding of 4‐(1‐pyrenyl)‐butyltrimethylammonium to poly(vinylbenzo‐18‐crown‐6) and poly(vinylbenzoglyme) in water
Authors: Roland Bruno , Wakui Tadahiro , Smid Johannes , De Schryver Frans C. 
Published: April 2003

AbstractThe binding of 41‐(1‐pyrenyl)butyltrimethylammonium bromide (PN+) to the neutral poly‐soap‐type polymers poly(vinylbenzo‐18‐crown‐6) (P18C6) and poly(vinylbenzoglyme) (PVBG) was studied by optical spectroscopy and fluorescence in the presence and absence of salts. Measurements of the respective binding constants were based on distinct differences in the optical absorption spectra of free and polymer‐bound PN+. When crown ether‐compelxable cations (e.g., K+) were added the adsorption of PN+ to P18C6 decreased as the neutral polymer was converted to a polycation. No decrease was found with PVBG because alkali ions do not complex significantly to this polymer in water. PN+ adsorption to both polymers rose rapidly, however, as the salt concentration increased. This effect was strongly anion‐dependent and increased in the order of Cl− < Br− < I− < CNS− < BPh4−. The increased binding was reflected in a higher binding constant and also in a larger number of bound PN+ molecules per polymer chain under saturation conditions. It is argued that the formation of ion pairs or larger ion clusters in the aqueous phase when anions are added forces more PN+ molecules to adsorb on the surface of the polymer coil to which they are bound as ion pairs or higher aggregates. Under saturation conditions enough PN+ molecules are bound to convert the pyrene monomer fluorescence spectrum into that of the excimer. These results are compared with data obtained for the anionic solute 4‐(1‐pyrenyl)butanoate in the presence of salts.
Ethynyl‐terminated polyarylates: Synthesis and characterization
Authors: Havens S. J. , Hergenrother P. M. 
Published: April 2003

AbstractHydroxy‐terminated polyarylates (HTPA) with number‐average molecular weights of approximately 2500, 5000, 7500, and 10,000 were synthesized and converted to corresponding 4‐ethynylbenzolyloxy‐terminated polyarylates (ETPA) by reaction with 4‐ethynylbenzoyl chloride. The terminal ethynyl groups were thermally reacted to provide chain extension and crosslinking. The cured ETPA exhibited higher glass transition temperatures (Tg) and better solvent resistance than a high molecular weight linear polyarylate. Solvent resistance was further improved by curing 2,2‐bis(4‐ethynylbenzoyloxy‐4′‐phenyl) propane, a coreactant, with ETPA at concentrations of approximately 10% (w/w).
Preparation and properties of polyamides containing p‐terphenyl units
Authors: Li Zao Bang , Ueda Mitsuru 
Published: April 2003

AbstractNovel polyamides that contained p‐terphenyl units were prepared with inherent viscosities in the range of 0.4–1.7 dL/g by the polycondensation of 4,4″‐dichloroformyl‐p‐terphenyl with aromatic diamines and 4,4″‐diamino‐p‐terphenyl with aromatic dicarbonyl chlorides. Polyamides composed of only paraoriented phenylene units were insoluble in all solvents and showed a high degree of crystallinity. A series of polyamides that contained p‐terphenyl units were more thermostable than corresponding polymers with p‐phenylene or biphenylene linkages.
Isothermal pyrolysis of cellulose untreated and treated with some flame‐retardants
Authors: Hirata Toshimi , Okamoto Hajime 
Published: April 2003

AbstractLinter cellulose, untreated and treated with boric acid, ammonium sulfamate, and guanidine sulfamate, was heated iosthermally in an imaging furnace thermal balance under a flow of helium gas to obtain kinetic parameters of the weight loss and changes in the elemental content and infrared (IR) spectra during pyrolysis. The weight, carbon, hydrogen, and oxygen losses of the untreated cellulose obey a zeroth‐order reaction at an early stage and a first‐order reaction at a later stage. The Arrhenius parameters for the weight and elemental losses are in agreement for both reactions. The activation energy and preexponential factor of the first‐order weight loss are 185 kJ/mol and 2.0 × 1013 s−1, respectively. The carbon, hydrogen, and oxygen losses of the samples treated with boric acid and guanidine sulfamate also obey a first‐order reaction at a later stage of pyrolysis. The results of the elemental and IR spectral analyses suggest that the zeroth‐ and first‐order reactions are caused mainly by the production of levoglucosan and that an initial rapid step, especially for the treated samples, is contributed by dehydration.
Effect solvatant des copolymères styrène–macromère a chaîne polyoxyéthylène. Influence du support polymère
Authors: Hamaide T. , Mariaggi N. , Foureys J. L. , Le Perchec P. , Guyot A. 
Published: April 2003

AbstractPolyoxyethylene macromers were used to prepare functionalized linear and crosslinked copolymers with styrene and divinylbenzene. Gel or macroporous resins were prepared. These copolymers and resins were used as anionic activators for the Williamson reaction of potassium phenoxide and alkyl bromides under solid–liquid or solid–liquid–liquid (triphase) conditions. In contrast to similar resins obtained from chemical grafting of polyoxyethylene onto chloromethylated styrene–divinylbenzene polymers, the activity factors were strongly dependent on the composition of the resins and their morphology: an optimum activity was obtained for a 0.05M fraction of macromers in soluble copolymers and crosslinked resins. In addition, a macroporous resin with large pores was more efficient than a gel‐type resin of similar composition. These effects are discussed in terms of accessibility of the activating group and compatibility of the support with the medium.
Liquid‐crystal polymers with tolan units
Authors: Al‐Dujaili A. H. , Jenkins A. D. , Walton D. R. M. 
Published: April 2003

AbstractA new series of liquid‐crystal polymers containing main‐chain mesogenic units is reported. The general repeating unit is
magnified image
where n = 4, 5, 6, 7, 8, 10, or 12.
Synthesis, charge transfer complexation, and photosensitivity of poly(N‐methyl‐3‐hydroxymethyl carbazolyl acrylate‐co‐acryloyl‐3′‐hydroxypropyl‐3,5‐dinitrobenzoate)
Authors: Natansohn Almeria 
Published: April 2003

AbstractThe synthesis of copolymers intrachain charge transfer complexes having as donor structural units N‐methyl‐3‐hydroxymethyl carbazolyl acrylate and as acceptor structural units acryloyl‐3′‐hydroxypropyl‐3,5‐dinitrobenzoate is presented. Charge transfer complexation in the copolymer and in the mixture of model compounds is analysed by NMR spectroscopy. Photosensitivity of the copolymers and of the corresponding mixture of model compounds is revealed by the increase of the ESR signal with illumination. Attempts to assign the ESR signal splitting to different radical structures are made. Besides an ESR signal increase dependent on light, a permanent increase in the number of spins is also noted as an effect of illumination.