bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of aromatic poly (ether sulfone)s and poly (ether ketone)s based on methyl‐substituted biphenyl‐4,4′‐diols
Authors: Keitoku Fumio , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Novel methyl‐substituted aromatic poly (ether sulfone)s and poly (ether ketone)s were synthesized from combinations of 3,3′,5,5′‐tetramethylbipheny‐4,4′‐diol and 2,2′,3,3′,5,5′‐hexamethylbiphenyl‐4,4′‐diol, and 4,4′‐dichlorodiphenyl sulfone and 4,4′‐difluorobenzo‐phenone by nucleophilic aromatic substitution polycondensation. The polycondensations proceeded quantitatively in a N‐methyl‐2‐pyrrolidone‐toluene solvent system in the presence of anhydrous potassium carbonate to afford the polymers with inherent viscosities between 0.86 and 1.55 dL/g. The methyl‐substituted poly (ether sulfone)s and poly (ether ketone)s showed good solubility in common organic solvents such as chloroform, tetrahydrofuran, pyridine, m‐cresol, and N,N‐dimethylacetamide. The tetramethyl‐ and hexamethyl‐substituted aromatic polyethers had higher glass transition temperatures than the corresponding unsubstituted polymers, and did not decompose below 350°C in both air and nitrogen atmospheres. The films of the methyl‐substituted poly (ether ketone)s became insoluble in chloroform by the irradiation of ultraviolet light, indicating the occurrence of photochemical crosslinking reactions. © 1994 John Wiley & Sons, Inc.
Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone
Authors: Han Haesook , Bhowmik Pradip K. , Lenz Robert W.
Published: April 2003

A series of fully aromatic, thermotropic polyesters, derived from 3,4′‐dihydroxybenzophenone and various aromatic dicarboxylic acids, was prepared by the high‐temperature solution polycondensation method and examined for thermotropic behavior by a variety of experimental techniques. The aromatic dicarboxylic acids used in this study were 2,6‐naphthalenedicarboxylic acid, 4,4′‐bibenzoic acid, and terephthalic acid.

The two homopolymers of 3,4′‐DHB with either 2,6‐NDA or 4,4′‐BBA formed nematic LC phases at 285°C and 255°C and also exhibited isotropization transitions (Ti) at 317°C and 339°C, respectively. The copolymer of 3,4′‐DHB with 50% TA and 50% 2,6‐NDA also formed a nematic LC phase and had a broader range of LC phase than that of its respective homopolymers. Two other copolymers of 3,4′‐DHB, both containing 50% 4,4′‐BBA, also formed nematic LC phases at low Tf values. All of the thermotropic polyesters had high thermal stabilities. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of poly (2‐vinylpridine)‐b‐poly (t‐butyl methacrylate)
Authors: Yin Rui , Hogen‐Esch Thieo E.
Published: April 2003

The synthesis of well defined and monodisperse (Mw/Mn ≤ 1.2) narrow molecular weight distribution poly (2‐vinylpyridine)‐poly (t‐butyl methacrylate) (P2VP‐PTBMA) AB block copolymers is carried out by initiation of 2‐vinylpyridine polymerization by 1,1‐diphenylhexyllithium in THF at‐78°C, followed by addition of TBMA and termination at −78°C using MeOH. The formation of the BAB block copolymer is carried out in a similar fashion except that 1,4‐dilithio‐1,1,4,4‐tetraphenylbutane is used as initiator. The corresponding synthesis of P2VP‐PMMA block copolymers is carried in a similar manner, except that 1‐2 equivalents of TBMA is used to end‐functionalize the living P2VP before the addition of MMA. Without the addition of TBMA, trimodal molecular weight distributions in P2VP‐b‐PMMA are obtained. All the block copolymers are characterized by Size Exclusion Chromatography (SEC), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC). © 1994 John Wiley & Sons, Inc.
Synthesis of polyester and copolyesters having amino acid moieties in the main chain
Authors: Wang Chonghui , Nakamura Shigeo
Published: April 2003

N, N‐di (2‐hydroxyethyl)‐3‐aminopropionic acid (M3) was synthesized and used for the preparation of a series of polyesters having amino acid moieties in the main chain and carboxyl groups as the side group. Polycondensation of M3, diols, bisphenol A, and isophthaloyl dichloride were performed in the presence of tertiary amine by solution and interfacial methods. Molecular weights of the polymers obtained by the solution method were not high, because oligomers produced at the early stage of reaction are ionized by H+ ions from the by‐product, and become nonreactive triethylamine hydrochloride. Polymers with high M̄w (1–10 × 104) were obtained in a high yield by organic/organic two‐phase interfacial polycondensation using DMAc and n‐heptane as solvents. The combined nucleophilic and basic complex catalytic action of N, N, N′, N′‐tetramethyl ethyiene diamine (TEMED) is suggested for the present organic phase/organic phase interfacial polycondensation. This method can be applied for the preparation of novel functional polyesters. © 1994 John Wiley & Sons, Inc.
Polymerization of surface‐active monomers. VIII. Tacticity of polymers prepared by radical polymerization of quaternary salts of dimethylaminoethyl methacrylate in micellar and isotropic media
Authors: Nagai Katsutoshi , Ohishi Yoshiyuki
Published: April 2003

The effect of monomer micellization on the polymerization was studied from the standpoint of stereochemistry in the polymerization. Quaternary salts (CnBr) of dimethylaminoethyl methacrylate with n‐alkyl bromide having N (=4, 8 and 12) carbon atoms were polymerized with radical initiators in isotropic and anisotropic media and the resulting polymers were converted to poly (methyl methacrylate) (PMMA) to determine their tacticity. Tacticities of poly (C12Br)s were little affected by initiators and solvents used for their preparations. There was little dependence of the tacticities on alkyl chain length (N) for poly (CnBr)s prepared in water and dimethylformamide (DMF). Most of polymers produced here conformed to Bernoullian propagation statistics and a definite difference was not found in the tacticities between the polymers prepared in isotropic and anisotropic media. From the results obtained here it was deduced that the micellar aggregation has little influence upon the stereochemistry in the polymerization of the quaternary monomers. © 1994 John Wiley & Sons, Inc.
Solid‐state polyamidation of hexamethylenediammonium adipate. II. The influence of acid catalysts
Authors: Katsikopoulos P. V. , Papaspyrides C. D.
Published: April 2003

Loss of diamine and distinct transition phenomena from the solid to the melt state restrain solid‐state polymerization (SSP) of nylon salts from industrial application. To depress these phenomena temperatures well below the melting point of the starting material are employed, resulting however in low reaction rates. The need to use catalysts arises and accordingly in this study hexamethylenediammonium adipate (HMA) particles were polymerized containing a strictly controlled amount of uniformly distributed catalyst. The catalysts included boric, sulphuric, and phosphoric acids with boric acid being the most effective in accelerating the reaction while eliminating the tendency to agglomeration. In general, catalyst concentration up to a critical value plays a considerable role in the overall behavior. Furthermore, in agreement with non catalytic processes, the reaction temperature remains an influential parameter. © 1994 John Wiley & Sons, Inc.
Synthesis and electronic properties of poly (E, E)‐[6.2]‐(2,5) thiophenophane‐1,5‐diene)
Authors: Guerrero Douglas J. , Glatzhofer Daniel T.
Published: April 2003

Cationic cyclopolymerization of (E, E)‐[6.2]‐(2,5) thiophenophane‐1,5‐diene (2) gave polymer 3 which has bridged thiophene rings pendant to the polymer backbone. The structural, thermal, and electronic properties of polymer 3 were compared to those of its benzene analogue (1) and its nonbridged analogue poly (2‐vinylthiophene) (5). The onsets of thermal degradation for polymers 3 and 5 under helium were 425 and 382°C, respectively. Polymer 3 exhibited conductivity in the 10−3−10−4 S/cm range when exposed to iodine vapor, four orders of magnitude higher than for 5 treated in the same manner. Apparent energies of activation for conductivity in iodine saturated polymers 3 (0.57 eV) and 5 (0.61 eV) were calculated from conductivity temperature dependence measurements. Conductivity parameters for iodine saturated 3 show both a higher level of conductivity and weaker temperature dependence than for the corresponding cyclopolymer 1 which has benzene rather than thiophene moieties, suggesting that greater charge generation occurs in 3, due to the lower oxidation potential of the thiophenophane repeat units. Differences in conductivity behavior for iodine saturated polymers 1, 3, and 5 are discussed in terms of both charge generation and mobility. © 1994 John Wiley & Sons, Inc.
Synthesis of polyphosphazenes bearing alkoxyethoxy and trifluoroethoxy groups
Authors: Matyjaszewski Krzysztof , Lindenberg Michael S. , Moore Mary K. , White Michael L.
Published: April 2003

The synthesis of various phosphoranimines including (CH3OCH2CH2O) (CF3CH2O)2PNSi(CH3)3, (CH3OCH2CH2OCH2CH2O) (CF3CH2O)2PNSi (CH3)3, (CH3OCH2CH2O)2(CF3CH2O) PNSi(CH3)3, and (CH3OCH2CH2OCH2CH2O)(CF3CH2O) PNSi(CH3)3 via the Staudinger reaction of (CH3)3SiN3 with the suitably substituted phosphite is reported. These monomers were polymerized using tetra‐n‐butylammonium fluoride and N‐methylimidazole in various solvents at several temperatures. In situ 31P‐NMR kinetic studies and Mn versus time studies were also performed for the monomers to understand the propagation mechanism. © 1994 John Wiley & Sons, Inc.
Syntheses and properties of related polyoxadiazoles and polytriazoles
Authors: Hensema E. R. , Sena M. E. R. , Mulder M. H. V. , Smolders C. A.
Published: April 2003

New aromatic poly‐1,2,4‐triazoles and poly‐1,3,4‐oxadiazoles are studied as thermally stable membrane materials. Various groups were introduced onto the pendant phenyl groups of poly‐1,2,4‐triazoles. Glass transition temperature, degradation temperature, and cold crystallization behavior were studied as a function of these groups. Cold crystallization appeared to be highly sensitive to macromolecular regularity. The solubility of poly‐1,3,4‐oxadiazoles was highly improved upon incorporation of 5‐t‐butylisophthalic, 1,1,3‐trimethyl‐3‐phenylindane, 4,4′‐(2,2′‐diphenyl) hexafluoro propane, and diphenyl ether groups into the polymeric main chain, whereas the high glass transition temperatures and degradation temperatures typical for aromatic poly‐1,3,4‐oxadiazoles were maintained. © 1994 John Wiley & Sons, Inc.
Ethylene‐vinyl acetate semi‐batch emulsion copolymerization: Use of factorial experiments for process optimization
Authors: Scott P. J. , Penlidis A. , Rempel G. L. , Lawrence A. D.
Published: April 2003

The application of factorial experiments to optimize the ethylene‐vinyl acetate emulsion polymerization process is described herein. A prior extensive experimental phase identified those variables that are most important for ethylene‐vinyl acetate emulsion copolymer production. The effects of temperature, pressure, added co‐solvent, vinyl acetate feed rate and emulsifier type, and concentration on the rate of polymerization, cumulative copolymer composition, molecular weight averages, and particle size and number are described in this article. The primary objectives of this research were to increase the amount of ethylene that could be incorporated into the copolymer at reduced temperatures and pressures (our target was a copolymer with an ethylene content of 30% by weight at 500 psig and 20°C versus the commonly employed industrial conditions in excess of 1000 psig), to achieve an improved process understanding, and to accumulate reliable data for modelling purposes. A copolymer containing 34% by weight of ethylene has been achieved at a pressure of 500 psig and a temperature of 20°C. The confusion present in the literature surrounding emulsifier effects has also been clarified. A discussion of hydrolysis, experimental reproducibility, and glass transition temperatures is also included. The sequential nature of the experimental process is illustrated throughout these optimizing experiments. © 1994 John Wiley & Sons, Inc.
Ring‐Opening polymerization of ε‐caprolactone by rare earth coordination catalysts. I. Characteristics, kinetics, and mechanism of ε‐caprolactone polymerization with nd(acac)3.3H2O‐ALET3 system
Authors: Shen Zhiquan , Chen Xianhai , Shen Youqing , Zhang Yifeng
Published: April 2003

Ring‐opening polymerization of ε‐caprolactone has been carried out by using rare earth coordination catalysts for the first time. The rare earth compounds, RE(acac)3.3H2O, Nd(P204)3, Nd(P507)3, Nd(naph)3, Nd(BA)3.2H2O, etc. (where RE = La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Lu, Y; acac = acetylacetone; BA = benzoylacetone), combined with trialkyl aluminum, greatly increased the degree of conversion and the molecular weight of poly(ε‐caprolactone) (PCL). The influence of reaction conditions on the polymerization of ε‐caprolactone catalyzed by the Nd (acac)3.3H2O‐AlEt3 system has been examined in detail. The kinetics indicates that the polymerization rate has the first‐order in monomer and a half‐order in catalyst. The overall activation energy of the ring‐opening polymerization amounts to 59.4 kJ/mol. By IR and UV‐Vis spectra, 1H‐ and 13C‐NMR data, it is assumed that the ring‐opening polymerization of ε‐caprolactone catalyzed by the Nd(acac)3.3H2O‐AlEt3 system proceeds via complexation of monomer to catalyst, acyl‐oxygen cleavage insertion propagation mechanism. © 1994 John Wiley & Sons, Inc.
The synthesis and cationic polymerization of multifunctional silicon‐containing epoxy monomers and oligomers
Authors: Crivello J. V. , Bi Daoshen
Published: April 2003

Several series of multifunctional silicon‐containing epoxide monomers and oligomers have been prepared using rhodium catalyzed hydrosilation reactions. Dialkyl and diarylsilanes can be condensed with vinyl epoxides to give high yields of the desired diepoxides while the hydrosilation of alkyl and aryl silanes yields a mixture of di and tri epoxy substituted products. The condensation of αω,SiH difunctional compounds with vinyl epoxides can be carried out regioselectively to give α‐hydrogen‐ω‐epoxy intermediates, which can be further reacted with di and tri olefins bearing terminal double bonds to give a series of well characterized epoxy functional oligomers. An investigation of the photoinitiated cationic polymerization of the monomers and oligomers, which were prepared during the course of these studies, was carried out. © 1994 John Wiley & Sons, Inc.
Synthesis of ion‐free latex particles composed of polybutadiene and poly (vinyl pyrrolidone) as polymer electrolyte materials
Authors: Rutt J. Steven , Ichino Toshihiro , Matsumoto Morihiko , Nishi Shiro
Published: April 2003

The synthesis of polybutadiene (PB) by emulsion polymerization with use of poly (vinyl pyrrolidone) (PVP) stabilizer was investigated. The goal was to prepare flexible latex films that clearly retain particle morphology in the solid state after heat treatment and contain no ionic, hydroxyl, or (primary, secondary) amino groups. The latex particle core composed of PB was nonpolar and rubbery, while the particle shell composed of PVP was polar and glassy. Average particle diameter was measured by the dynamic light scattering technique, and particles were imaged by scanning and transmission electron microscopic analyses. Dialysis of the latices resulted in successful exchange of the dispersion medium without precipitation. © 1994 John Wiley & Sons, Inc.
Reduced titanium dioxide as support for Ziegler–Natta catalysts
Authors: Jericó Soraya , Schuchardt Ulf , Kaminsky Walter , Joekes Inés
Published: April 2003

Titanium tetrachloride heterogenized on reduced TiO2has been studied as a catalyst for ethylene polymerization. The catalyst has good storage stability and exhibits good activity for ethylene polymerization. The polymer chains grow linearly during ca. 1 h, giving an average molecular weight of up to 2.5 × 106which indicates that practically no β‐elimination occurs. The activity of the catalyst at 50°C, based on Ti(III), is 7.6 × 106PE/mol Ti h bar and based on the quantity of polyethylene formed it is 1.25 × 106g PE/mol Ti h bar. The molecular weight of the polymer can be controlled with the addition of hydrogen, under 0.5 bar hydrogen, polyethylene with a molecular weight of 411,000 and a relatively low polydispersity index of 2.2 is obtained. The catalyst shows good thermal stability; the Arrhenius activation energy is 31.8 kJ/mol for the polymerization. The catalyst is also active for propylene polymerization, giving 3 × 106g PP/mol Ti h bar with the high isotacticity of 93%. © 1994 John Wiley & Sons, Inc.
Ethylene‐hindered amine copolymer: A self‐stabilized polyolefine
Authors: Bertolini Guglielmo , Lanzini Luigi , Marchese Luca , Roggero Arnaldo , Lezzi Alessandro , Costanzi Silvestro
Published: April 2003

Monomers having a norbornene as polymerizable group and a 2,2,6,6‐tetramethyl piperidine as stabilizing moiety were prepared. This monomer was successfully copolymerized with ethylene using VAc3/AlEt2Cl as the catalytic system. Copolymers exhibited better stability under accelerated aging than polyethylene stabilized by classical blending with commercial hindered amines. Any attempt made to obtain copolymers using a high activity TiCl4/MgCl2 catalyst was unsuccessful. © 1994 John Wiley & Sons, Inc.
Prediction of polymer composition in batch emulsion copolymerization
Authors: Noël Lilian F. J. , Van Zon Jan M. A. M. , Maxwell Ian A. , German Anton L.
Published: April 2003

Monomer partitioning in emulsion copolymerization plays a key role in determining composition drift and polymerization rates. The combination of recently developed thermodynamically based monomer partitioning relationships with mass balance equations, makes predictions of monomer partitioning in emulsion copolymerizations possible in terms of monomer mole fractions and monomer concentrations in the particle and aqueous phases. Using this approach, the effects of monomer to water ratios and polymer volumes on the monomer mole fraction within the polymer particle phase in a nonpolymerizing system at thermodynamic equilibrium can be determined. Comparison of these monomer partitioning predictions with experiments for the monomer system methyl acrylate—vinyl acetate shows good agreement. Furthermore, composition drift occurring in a polymerizing system as a function of conversion can be predicted if the assumption is made that equilibrium is maintained during reaction. Comparison of predictions with experimental results for emulsion copolymerizations of the monomer systems methyl acrylate—vinyl acetate and methyl acrylate—indene shows good agreement. © 1994 John Wiley & Sons, Inc.
Reactivity characteristics of squid β‐chitin as compared with those of shrimp chitin: High potentials of squid chitin as a starting material for facile chemical modifications
Authors: Kurita Keisuke , Ishii Shigeru , Tomita Koji , Nishimura Shin‐Ichiro , Shimoda Kayo
Published: April 2003

Chemical reactivity of β‐chitin isolated from squid pens has been examined in various reactions to elucidate the possibility of facile modifications in simple manners leading to the preparation of derivatives with well‐defined structures. β‐Chitin swelled in common solvents such as methanol and pyridine unlike the ordinary α‐chitin and exhibited much higher reactivity than β‐chitin. Free amino groups present in β‐chitin were easily and selectively acetylated with acetic anhydride in methanol to give chitin with a uniform structure, poly(N‐acetyl‐D‐glucosamine). When acetylation reaction was carried out in pyridine, O‐acetylation proceeded smoothly besides N‐acetylation. In the presence of 4‐dimethylaminopyridine as the catalyst, even full acetylation was achieved under mild conditions. Tosylation was also quite efficient in pyridine without side reactions such as N‐deacetylation which is unavoidable in the tosylation of α‐chitin. β‐Chitin also enabled direct tritylation in pyridine in the presence of 4‐dimethylaminopyridine. All these reactions were quite sluggish with β‐chitin, and no reactions or only very low extents of substitution were observed, indicating the high potential of β‐chitin as a versatile starting material for facile modification reactions. © 1994 John Wiley & Sons, Inc.
Preparation of polyalkylviologen–polyanion complexes and their applications to the debromination of diphenyl bromomethane under heterophase condition
Authors: Liu Futian , Yu Xianda , Li Shuben
Published: April 2003

Several polyelectrolyte complexes were prepared by the reaction of polyalkylviologens [polyethylviologen (PEV2+), polypropylviologen (PPrV2+), and polybutylviologen (PBV2+)] with polyanions [sodium alginic (ALG), sodium polyacrylate (PAA), or sodium polystyrenesulfonate (PSS)]. These complexes were used as electron‐transfer catalysts (ETC) on the debromination of diphenyl bromomethane (Ph2CHBr) under heterophase condition [reductant: Na2S2O4, in H2O (liquid)‐polyelectrolyte complex(S)—Ph2CHBr in CH2Cl2]. The work showed that these complexes could induce the debromination of Ph2CHBr to afford tetraphenyl ethane, and different polyanions in the complexes also affected the mediating abilities. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of new fluorescent poly(arylene ether)s
Authors: Matsuo Shigeru , Yakoh Naoto , Chino Shinji , Mitani Masahiro , Tagami Sanae
Published: April 2003

The poly(arylene ether)s were prepared by the nucleophillic aromatic substitution polymerization of phenolphthalin and its derivatives with activated aromatic difluorides. The polymers had glass transition temperatures ranging from 210 to 240°C. Though the monomers have no fluorescence, the resulting polymers fluoresced a light green color in solid and solution states. The maximum excitation and emission wavelengths are 420 nm and 470 nm, respectively. In the polymer solutions, the fluorescence intensity decreased gradually, but the intensity was recovered by heating the polymer at 220°C for a few minutes. The fluorescent polymer had a stable radical. A model compound having the same repeating unit of the polymer was also prepared. The fluorescence properties of this model were almost the same as those of the polymers. © 1994 John Wiley & Sons, Inc.
Synthesis and thermal behavior of side‐chain liquid crystalline polymethacrylates containing tolane‐based mesogenic side groups
Authors: Hsieh Chang‐Jyh , Wu Shih‐Hsiung , Hsiue Ging‐Ho , Hsu Chain‐Shu
Published: April 2003

The synthesis and characterization of nine polymethacrylates containing 4‐alkoxy‐4′‐trifluoromethyltolane, 4‐alkoxy‐4′‐cyanotolane, and 4‐alkoxy‐4′‐nitrotolane side groups were described in this study. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry, optical polarizing microscopy, and x‐ray diffraction. All of the obtained monomers exhibit no mesophase, while most of the synthesized polymers reveal enantiotropic mesomorphism. The polymethacrylate containing 4‐propanyloxy‐4′‐nitrotolane side groups was the only one which shows no mesomorphic behavior. Both the spacer length and the nature of terminal groups have profound influence on the phase transition temperatures and thermal stability of the mesophase. The polymers with longer spacers tend to form a more ordered mesophase with a wider temperature range. Among three polymers with the same spacer length, the polymer with a trifluoromethyl terminal end group is inclined to form a more ordered mesophase than the other two polymers. No side chain crystallization occurred for all obtained polymers. © 1994 John Wiley & Sons, Inc.
1H‐NMR and UV studies of Rh complexes as a stereoregular polymerization catalysts for phenylacetylenes: Effects of ligands and solvents on its catalyst activity
Authors: Tabata Masayoshi , Yang Wu , Yokota Kazuaki
Published: April 2003

Phenylacetylene and its homologues bearing methoxy or chloro groups in the para position of the phenyl ring were stereoregularly polymerized by Rh complex catalysts, e.g., [Rh (norbornadiene) Cl]2, in the presence of various solvents. The 1H‐NMR and UV study of the Rh complex showed that the activity of the Rh catalysts greatly depends upon not only the ligand in the Rh catalyst but also on the solvent used, e.g., polyphenylacetylene with a highly cis‐transoidal content was quantitatively obtained when norbornadiene was coordinated as the ligand, and triethylamine (TEA) was used as solvent, whereas tetrahydrofuran (THF) and benzene reduced the cis content. It was also found that the Rh catalyst as a dimer complex dissociates into the monomeric species not only when TEA was used but also when alcohol, benzene, and THF were used. The resulting monomeric species was considered as the important propagation species in this polymerization. The sharp line width observed in the 1H‐NMR spectrum of polyphenylacetylene and its homologues which were prepared in ethanol or TEA was interpreted by the narrow chemical shift distribution arising from the high cis content. © 1994 John Wiley & Sons, Inc.
Optically active polymers containing side‐chain photochromic moieties: Synthesis and chiroptical properties of copolymers of trans‐4‐(phenylazo)‐1‐naphthyl acrylate and trans‐4‐(1‐naphthylazo)‐phenyl acrylate with ()‐menthyl acrylate
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo
Published: April 2003

The synthesis of photochromic optically active copolymers from trans‐4‐(phenylazo)‐1‐naphthyl acrylate (PANA), or trans‐4‐(1‐naphthylazo)‐phenyl acrylate (NAPA), and (−)‐menthyl acrylate (MtA) is described. The copolymers prepared, having different contents of trans‐phenylazonaphthalene moieties, have been characterized by IR, 1H‐NMR, UV, and GPC techniques. The chiroptical properties have been investigated by circular dichroism (CD) and the induced optical activity on the side‐chain trans‐phenylazonaphthalene chromophores discussed in terms of different conformational situations of the macromolecules in both the copolymer series. © 1994 John Wiley & Sons, Inc.
A reexamination of the degradation of polyvinylchloride by thermal analysis
Authors: Chatterjee Nandini , Basu Sudhapada , Palit S. K. , Maiti Mrinal M.
Published: April 2003

Degradation of polyvinylchloride has been reexamined in the light of its DT‐DSC‐TG analytical behavior up to a temperature of 1000°C in an inert atmosphere. Four distinct stages of degradation have been identified. The first stage is almost eventless with no change in weight for untreated PVC samples. The second stage is almost exclusively dehydrochlorination. The third stage appears to be a structural reorganization involving such processes as cis‐trans isomerization, aromatization, and crosslinking. The fourth stage appears to be a structural degradation and is associated with the evolution of hydrocarbons. The role of liberated hydrogen chloride has been better appreciated in catalyzing the above secondary reactions on the polyene residue obtained on partial or total dehydrochlorination. The effect of the particle dimension and chemical and physical pretreatments of the samples, such as low temperature dehydrochlorination by an alkali and vacuum heat treatment, respectively, on the degradation pattern has been studied. © 1994 John Wiley & Sons, Inc.
Syntheses of homopolymer and water‐soluble polymers containing tetraphenylporphinatomanganese(III) complex, and ligand substitution reaction for anionic ligand
Authors: Sumi Katsuhiro , Kimura Mutsumi , Nakamura Isei
Published: April 2003

A vinyl monomer containing the pendant tetraphenylporphyrin (TPP) group, 4‐vinyltetraphenylporphyrin (VTPP), was synthesized. A homopolymer (PVTPP) which is insoluble in water, and three water‐soluble polymers were obtained by radical polymerization. The water‐soluble polymers are two anionic polymers (PVPTSPP and PVTPP‐StSO3) and a cationic polymer (PVTPP‐VPyM). PVPTSPP has sulfonic acid groups in a TPP group and very high charge density. PVTPP‐StSO3 was obtained by copolymerization of VTPP and sodium 4‐styrenesulfonate. PVTPP‐VPyM was obtained by quarternarization of a copolymer of VTPP and 4‐vinylpyridine. Polymeric manganese(III) complexes (PMn‐VTPP, PMnVPTSPP, PMnVTPP‐StSO3, and PMnVTPP‐VPyM) were prepared from the polymers and manganese acetate. The acetate ligand in PMnVTPP can be easily substituted by another ligand such as Cl−, AcO−, OH−, and SCN−. The substitution reaction occurs in the interface between water and chloroform. The sulfonated homopolymer, PMnVPTSPP, cannot incorporate with anionic ligands because of the strong electrostatic repulsion. In the anionic copolymer, PMnVTPP‐StSO3, the ligand substitution reaction with SCN ligand needs activation energy of 53 kJ/mol. In the cationic polymer complex, PMnVTPP‐VPyM, the OH ligand can be easily substituted with the SCN ligand and the equilibrium constant of the reaction was estimated at 1.38 × 10−3. © 1994 John Wiley & Sons, Inc.
Studies on the formation of PEN. I. Kinetic aspects of catalyzed reaction in transesterification of dimethylnaphthalate with ethylene glycol
Authors: Wang Chun‐Shan , Sun Yih‐Min
Published: April 2003

The transesterification of dimethyl naphthalate (DMN) with ethylene glycol (EG) was kinetically investigated in the presence of various catalysts at 185°C. The transesterification was assumed to obey first‐order kinetics with respect to DMN and EG, and a rate equation was derived. The rate constant of transesterification which was calculated from the quantity of methanol which distilled from the reaction vessel was used to evaluate the activity of each metal compound. The first‐order dependence on the catalyst concentration is valid below a critical concentration which was found to be dependent on the catalyst type. The order of decreasing catalytic activity of various metal ions was found to be: Pb ≥ Zn > Co > Mg > Ni ≥ Sb, but in the case of highly basic metal salts, the rate constants were found to be extremely large at the initial stage of the reaction, and then rapidly decreased with the progress of the reaction. Effects of reaction temperature were also discussed. The activation energies for zinc acetate and lead acetate were 97.84 and 108.8 kJ/mol, respectively, which were calculated from the Arrhenius equation. © 1994 John Wiley & Sons, Inc.
Macrothiuram disulfide for the free radical synthesis of PDMS‐vinyl triblock copolymers. II. Studies of chain transfer
Authors: Clouet G. , Kayser D.
Published: April 2003

Chain transfer constants (Ctr) for thiuram disulfide (TD) groups, included in the backbone of polydimethylsiloxane (PDMS) of different chain lengths, in methyl methacrylate (MMA) and styrene (St) were determined from measurements of the degree of polymerization. Two methods were used. The first consisted of using the initiation and transfer properties of the thiuram disulfides groups, and the second, of using a more efficient free radical initiator than TD groups, in which case the former behaves only as a transfer agent. In both the methods, the Ctr of TD was evaluated in bulk polymerization of MMA at 60, 70, 80, and 90°C. Using the first method, the Ctr of TD was measured also in solution polymerization of MMA in toluene at 100°C and, with the second one, in bulk polymerization of styrene at 60, 80, and 90°C. PDMS‐based macrothiuram disulfide (macroiniferter) behaves as an “azeotropic” transfer agent for MMA and styrene at 125°C and 110°C, respectively. © 1994 John Wiley & Sons, Inc.
Two‐Dimensional polymerization of supramolecular assemblies: Synthesis and bilayer polymerization of lipids containing α‐methylene‐substituted acyl chains
Authors: Lee Youn‐Sik , O'Brien David F.
Published: April 2003

Polymerization of lipid assemblies may be usefully employed to alter the properties of the assemblies. The possible locations of the reactive group in the lipids include (1) the chain terminus, (2) the head group, and (3) near the lipid backbone. The third strategy yields polymerized assemblies which retain their head group functionality and lipid chain motion. We have designed and synthesized new members of this later category by the use of 2‐methylene‐substituted acyl chains. The main transition temperature (Tm) from gel to liquid crystalline phase of hydrated bilayers of 1‐palmitoyl‐2‐(2‐methylene)palmitoyl‐sn‐glycero‐3‐phosphocholine (1) and the disubstituted 1,2‐bis(2‐methylenepalmitoyl)‐sn‐glycero‐3‐phosphocholine (2) were 33.6 and 25.3°C, respectively. The Tm of the mono‐substituted 1‐oleoyl‐2‐(2‐methylene)palmitoyl‐sn‐glycero‐3‐phosphocholine (3) bilayers was detected in a range from −15 to −10°C by x‐ray diffraction. Hydrated bilayers of each individual lipid were successfully polymerized with a water‐soluble initiator, azobis(2‐amidinopropane) dihydrochloride (AAPD). These results indicate the lipid 2‐methylene groups are accessible to the water interface. Thermal polymerization of the mono‐substituted lipids in aqueous suspensions with AAPD, yielded oligomers. However the bis‐2‐methylene PC (2) was successfully polymerized to yield stabilized crosslinked bilayers. © 1994 John Wiley & Sons, Inc.
Self‐Crosslinkable poly(arylene ether)s containing pendent phenylenetriazene groups
Authors: Lau Aldrich N. K. , Vo Lanchi P. , Fone Matilda M. , Duff David W. , Merlino Gloria
Published: April 2003

Self‐crosslinkable poly(arylene ether)s 6, and 8, containing pendent triazene groups were prepared by nucleophilic substitution reaction of poly(arylene ether)s 5, and 7, respectively, with 1‐[4‐(4‐hydroxyphenoxy)phenylene]triazenes, 4, in the presence of potassium carbonate in N,N‐dimethylacetamide. A series of triazenes 4 containing various substituents have been synthesized. Self‐crosslinkable polymer 6e containing phenyl‐substituted triazene pendants can be crosslinked at 215°C, which is about 40°C lower than the glass transition temperature of the virgin base polymer 5. The degree of crosslinking can be tailored by varying the concentration of the pendent phenylenetriazene groups in the polymer. After curing, the flexible polymer films (ca. 10 μm thick) exhibit high gel contents, increased glass transition temperatures, improved resistance to organic solvents, and little change in dielectric constant and thermal stability. These self‐crosslinkable poly(arylene ether)s are potential candidates for electronic applications. © 1994 John Wiley & Sons, Inc.
The cationic polymerization of N‐vinyl‐2‐pyrrolidone initiated electrochemically by anodic polarization on a Pt surface
Authors: Léonard‐Stibbe E. , Lécayon G. , Deniau G. , Viel P. , Defranceschi M. , Legeay G. , Delhalle J.
Published: April 2003

The electroinitiated polymerization of N‐vinyl‐2‐pyrrolidone has been investigated. After electrolysis at controlled potential, a thin, covering, and homogeneous film of poly(N‐vinyl‐2‐pyrrolidone) appears on the electrode. The insolubility of the polymer in its classical solvents implies the existence of a true chemical grafting of macromolecules on the platinum surface. Chain propagation occurs by a cationic mechanism initiated by a direct electron transfer leading to grafted cations on the surface, followed by the nucleophilic attack of neutral molecules. The molecular weight of the polymer was estimated by gel permeation chromatography after having mechanically removed the film from the electrode. A molecular weight distribution curve showing an average value of 16,000 was observed. © 1994 John Wiley & Sons, Inc.
Rigid‐rod polymers with polysiloxane side chains. I. Synthesis and characterization of rigid‐rod polyimides with polysiloxane side chains and their compatibility with linear polysiloxanes
Authors: Itoh Maki , Mita Itaru
Published: April 2003

Rigid‐rod aromatic polyimdies having polydimethylsiloxane side chains were prepared for the purpose of dispersing rigid‐rod molecules in silicone matrices for molecular reinforcement. The polyimides were obtained by imidizing the polyamide‐acids bearing the side chains either thermally or chemically, which were synthesized by reacting 4,4′‐diaminobiphenyl‐terminated polysiloxane macromonomers with pyromellitic dianhydride in THF. The polyamide‐acid films obtained by removing the solvent were soluble in THF, but the polyimides were insoluble in any common solvent. The polyimides showed no melting transition below 350°C on DSC analysis, at which temperature the side chain started decomposing. Although all the polyimides were anisotropic as observed by a polarizing microscope, x‐ray diffraction analysis suggested the presence of only limited chain organization. Blends with linear polydimethylsiloxanes were prepared by casting the THF solution containing the polyamide‐acid and the polydimethylsiloxane, followed by solvent evaporation and thermal imidization. With relatively longer side chains, the polyimides were proved to be compatibilized with polydimethylsiloxanes. © 1994 John Wiley & Sons, Inc.
Whiskers. VIII. A convenient synthesis of poly(4‐hydroxybenzoate) whiskers and their application in composites of nylon‐6
Authors: Kricheldorf Hans R. , Adebahr Thorsten , Wahlen Lars
Published: April 2003

Whiskers of poly(4‐hydroxybenzoate) [poly(4‐HBA)] were prepared by polycondensation of free 4‐hydroxybenzoic acid with acetic anhydride and pyridine in a high boiling inert solvent. The purity of the monomer is decisive for the success of the synthesis. For a less pure 4‐hydroxybenzoic acid, the preparation of acetylated oligomers with acetylchloride, followed by polycondensation of the isolated oligomers is a suitable alternative. Whiskers, with a solid‐solid phase transition at 364°C were obtained, which is the highest temperature reported for this transition so far. Two batches of composites were prepared from nylon‐6 using polyester whiskers with an alkaline or an acidic surface treatment. A third batch was prepared using poly(ester‐amide) whiskers. The mechanical properties of these composites indicate that the surface treatment does not play any role, and that the poly(esteramide)s are inferior to the polyester whiskers, because they are not single crystals. © 1994 John Wiley & Sons, Inc.
Synthesis of novel polymer containing selenium by radical addition polymerization of 1,4‐benzenediselenol to 1,4‐divinylbenzene
Authors: Kobayashi Eiichi , Akiba Yasuhide , Aoshima Sadahito
Published: April 2003

A novel addition polymerization of 1,4‐benzenediselenol (BDSe) to 1,4‐divinylbenzene (DVB) was carried out with various azo radical initiators [dimethyl 2,2′‐azobisisobutyrate (DAIB), 1,1′‐azobis(1‐acetoxy‐1‐phenylethane) (AAPE), and AIBN] in toluene at 65 and 75°C under a nitrogen atmosphere. The polymerization proceded without an induction period, and pale‐yellowish powder polymers were obtained in 89% yields for 75 h (DAIB), 89% yields for 24 h (AAPE), and 60% yields for 8 h (AIBN). The molecular weight (Mw) of the insoluble polymers in toluene was about 4000 (IBN) to 14,000 (DAIB or AAPE) by GPC. The polymer had an alternating structure of BDSe to DVB units by 1H‐NMR, IR analyses, and selenium contents, but the polymer contained the diselenide linkage by Raman spectroscopy. By AIBN initiator, the yield of the polymers did not increase over 60% and higher molecular weight polymer was hardly obtained. According to the model addition reaction of benzeneselenol to styrene by AIBN, it was found that AIBN was consumed by the side reaction between dimethyl‐N‐(2‐cyano‐2‐propyl)ketenimine derivedAppl 11 from AIBN and benzeneselenol to give the adduct C, MH+ 295 by DCI MS. On the other hand, DAIB and AAPE initiators, which do not form a ketenimine intermediate, gave the polymers of higher molecular weight in a higher yield. The polymer film exhibited high refractive index (n25D = 1.81) and a reversible phase transition between a transparency and an opaque by thermal mode. © 1994 John Wiley & Sons, Inc.
Synthesis and photopolymerization of 1‐propenyl glycidyl ether
Authors: Crivello J. V. , Kim Whan‐Gi
Published: April 2003

The ambifunctional monomer, 1‐propenyl glycidyl ether, was prepared from allyl glycidyl ether, by a ruthenium‐catalyzed isomerization reaction in high yield. 1‐Propenyl glycidyl ether undergoes facile photoinduced cationic polymerization to yield a crosslinked polymer. The structure of this polymer was studied using 1H‐ and, 13C‐NMR spectroscopies and employing well‐characterized related polymers as models. The model polymers were prepared by the cationic polymerization of allyl glycidyl ether with BF3OEt2 followed by isomerization of the pendant allyl groups by a ruthenium catalyst. Subsequently, the resulting polyether‐bearing pendant 1‐propenyl ether groups was subjected to a diaryliodonium salt‐photoinitiated polymerization. A comparison of the spectra of the polymers indicated the presence of cyclic acetal units in the polymer backbone. © 1994 John Wiley & Sons, Inc.
Photomodification of a poly(acrylonitrile‐co‐butadiene‐co‐styrene) containing diaryltetrazolyl groups
Authors: Darkow Rita , Yoshikawa Masakazu , Kitao Toshio , Tomaschewski Georg , Schellenberg Jürgen
Published: April 2003

A new type of membrane polymer, containing a photosensitive moiety, was synthesized. The photochemically induced functionalization and crosslinking of poly [acrylonitrile‐co‐butadiene‐co‐styrene‐co‐2‐(4‐ethenyl) phenyl‐5‐phenyl‐2H‐tetrazole], ABSV, has been studied. A variety of dipolarophiles and phenolic compounds were applied to alter the polarity of the membrane surface. The functionalization and crosslinking were initiated by photoirradiation. DSC and contact angle measurements were used to characterize the modified polymer. Pervaporation experiments with a cyclohexane/benzene mixture (5 wt% benzene) were carried out, with the results showing, that the photochemical treatment significantly effects both permselectivity and flux. Solubility parameters were found to be useful to interpret the pervaporation data. In general, the selectivity towards benzene increases with the polarity of the membrane surface, i.e., with increasing polarity of the modifier. A mechanism to explain the influence of both functionalization and crosslinking on the membrane performance, is proposed. © 1994 John Wiley & Sons, Inc.
Cationic polymerization of vinyl monomers initiated by 10‐methylphenothiazine cation radicals
Authors: Nomura Shigeki , Morishima Yotaro , Koremoto Toshihiro , Kamachi Mikiharu
Published: April 2003

A small quantity of 10‐methylphenothiazine cation radical (MPT.+), electrochemically prepared and stocked in acetonitrile solution, initiated cationic polymerizations of n‐butyl, t‐butyl, and 2‐methoxyethyl vinyl ethers and p‐methoxystyrene, while no initiation occurred for phenyl vinyl ether, styrene, methyl methacrylate, and phenyl glycidyl ether. 1H‐NMR studies of oligomers and low molecular weight compounds isolated from the reaction mixture for the polymerization of t‐butyl vinyl ether in the presence of a small amount of D2O indicated that electron transfer from the monomer to MPT.+ was involved in the initiation step. 1H‐ and 13C‐NMR and MO calculation implied that monomers with higher electron densities on the vinyl groups and with lower ionization potentials were more susceptible to the initiation of MPT.+. © 1994 John Wiley & Sons, Inc.
Thermogravimetric analysis of poly(alkyl methacrylates) and poly(methylmethacrylate‐g‐dimethyl siloxane) graft copolymers
Authors: Smith S. D. , Long T. E. , Mcgrath J. E.
Published: April 2003

The thermal stabilities of various poly(alkyl methacrylate) homopolymers and poly(methyl methacrylate‐g‐dimethyl siloxane) (PMMA‐g‐PSX) graft copolymers have been determined by thermogravimetric analysis (TGA). As expected, the thermal stabilities of poly(alkyl methacrylates) were a function of the ester alkyl group, and polymerization mechanism. In particular, thermally labile linkages, which result from termination during free radical or nonliving polymerization mechanisms, decrease the ultimate thermal stabilities of the polymers. However, graft copolymers, which were prepared by the macromonomer technique with free radical initiators, exhibited enhanced thermal stability compared to homopolymer controls. A more complex free radical polymerization mechanism for the macromonomer modified polymerization may account for this result. © 1994 John Wiley & Sons, Inc.
Synthesis and polymerization of cyano‐substituted monomers derived from 4‐amino‐α‐methyl‐β,β′‐dicyanostyrene
Authors: Mikroyannidis John A.
Published: April 2003

A novel class of polymer precursors of the general formula, magnified image where A is an aromatic structure bearing amide or imide linkages, were synthesized. More particularly, 4‐aminoacetophenone was condensed with malononitrile to afford 4‐amino‐α‐methyl‐β,β′‐dicyanostyrene (1). The condensation of the latter with half molar amount of terephthaloyl dichloride, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride yielded the polymer precursors. In addition, compound 1 was condensed with an equimolar amount of maleic anhydride to afford the corresponding maleimide. The monomers were characterized by elemental analyses, FT‐IR, 1H‐NMR, and DTA. Crosslinked resins were obtained upon curing the monomers at 300°C for 72 h. They were stable up to 381‐422°C in N2 or air and afforded anaerobic char yields of 64‐68% at 800°C. © 1994 John Wiley & Sons, Inc.
Hexafluoro‐2‐hydroxy‐2‐propyl‐modified polyisoprene blends
Authors: Coleman Michael M. , Yang Xiaoming , Painter Paul C. , Kim Young H.
Published: April 2003

Dimensionless equilibrium constants describing the self‐association of the hexafluoro‐2‐alkyl‐2‐propanol group have been determined from infrared spectroscopic data. Corresponding values of these equilibrium constants for a fully modified polyisoprene containing the hexafluoroisopropanol group (PHFPI) were calculated by taking into account differences in the molar volume of the model and the specific repeat unit of the polymer. Equilibrium constants describing the inter‐association of PHFPI with methacrylate, acrylate, and acetoxy type carbonyl groups were obtained from spectroscopic studies of miscible PHFPI blends with poly(n‐butyl methacrylate), poly(methyl acrylate), and an ethylene‐co‐vinyl acetate copolymer containing 70 wt% vinyl acetate. The set of equilibrium constant values were then used to calculate theoretical miscibility windows for the complete range of PHFPI blends with poly(n‐alkyl methacrylate)s and four copolymers, ethylene‐co‐methyl methacrylate, styrene‐co‐methyl acrylate, ethylene‐co‐methyl acrylate, and ethylene‐co‐vinyl acetate. Experimental infrared studies confirm the general validity of the predicted miscibility windows. © 1994 John Wiley & Sons, Inc.
Synthesis of new siloxane urethane block copolymers and their properties
Authors: Benrashid Ramazan , Nelson Gordon L.
Published: April 2003

Siloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studies, including ESCA, EDS, and FT‐IR, show well segregated block copolymers with enhanced siloxane on the surface. DSC studies show a low mp (‐44°C) for the soft segment and a Tg for the hard segment above room temperature. These materials show higher thermal stability compared to polyether urethane block copolymers. These copolymers also show relatively good resistance to exposure to oxygen plasma and show improved flame retardancy compared to nonsiliconated, polyether polyurethane block copolymers. © 1994 John Wiley & Sons, Inc.