bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoinitiated cationic polymerization of oxetane formulated with oxirane
Authors: Sasaki Hiroshi , Rudzinński Jerzy M. , Kakuchi Toyoji
Published: April 2003

Photoinitiated cationic polymerization of oxetane, oxirane (epoxide), and a formulation of both was carried out and their reactivity compared. To investigate a formulated system of oxetane and oxirane in photoinitiated cationic polymerization, computational and experimental methods were used. In the computational study, we employed a semiempirical molecular orbital method (AM1). On the other hand, the reactivities of each system were evaluated and compared experimentally by a real‐time FT‐IR method. The computational study reveals that oxetane seems to polymerize in SN2 mechanism, but two possibilities, of SN1 mechanism through the α‐cleavage and of SN2 mechanism through β‐cleavage, are implied for oxirane. Using the real‐time FT‐IR method, the formulation of oxetane and oxirane was proved to possess rather high reactivities of oxetane toward photoinitiated cationic polymerization. The formulated system exhibited slightly lower number‐average molecular weight than oxetane but higher than oxirane. These experimental observations are well explained in terms of the calculated reaction paths. © 1995 John Wiley & Sons, Inc.
Electroinitiated polymerization of allylphenylether
Authors: Şen Şadi , Usanmaz Ali , Önal Ahmet M.
Published: April 2003

Electroinitiated polymerization of allylphenylether via constant potential electrolysis was accomplished in acetonitrile at room temperature. Electroinitiated polymerization of the monomer yielded insoluble polymers on the surface of the anode together with soluble polymers in the bulk solution. The structural analyses of the polymers were done by 1H‐NMR and FTIR spectroscopy. 1H‐NMR results showed that monosubstituted aromatic ring of the monomer becomes tri‐substituted during the electroinitiated polymerization. The effect of monomer concentration and applied potential on the rate of electroinitiated polymerization were also studied. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of thianthrene‐containing poly(benzoxazole)s
Authors: Johnson Randy A. , Mathias Lon J.
Published: April 2003

New thioether‐ and thianthrene‐containing poly(benzoxazole)s (PBOs) were synthesized from 4,4′‐thiobis[3‐chlorobenzoic acid] and thianthrene‐2,7‐ and ‐2,8‐dicarbonyl chlorides with commercially available bis‐o‐aminophenols. Polymers were prepared via solution polycondensation in poly(phosphoric acid) at 90–200°C. Transparent PBO films were cast directly from polymerization mixtures or m‐cresol. The films were flexible and tough. Non‐fluorinated PBOs were soluble only in strong acids and AlCl3/NO2R systems by forming complexes with the benzoxazole heterocycle Glass transition temperatures ranged from 298–450°C, and thermogravimetric analysis showed good thermal stabilities in both air and nitrogen atmospheres. © 1995 John Wiley & Sons, Inc.
Curing of a maleimide model compound
Authors: Maes C. , Devaux J. , Legras R. , Parsons I. W.
Published: April 2003

A monofunctional maleimide‐ended model compound was synthesized and purified. The thermal curing of this compound was followed by size exclusion chromatography and the molecular masses of the oligomers formed during the curing reaction were determined by mass spectroscopy. It was found that high molecular mass species were not thermally stable. At high temperature and after enough time, a strong decrease in the polydispersity of the oligomers and a significantly preferential formation of trimer were observed. From 13C‐NMR characterization, a five membered ring structure was found for the trimer, which explains the thermal stability of this species. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of aromatic polyamides with oligobenzamide pendent groups. I. Poly‐5‐(4‐benzoylamino‐1‐benzoylamino)isophthalamides
Authors: Lozano Angel E. , Abajo Javier De , De La Campa José G. , Preston Jack
Published: April 2003

A series of polyisophthalamides having pendent oligomeric benzamide groups were prepared by the Yamazaki reaction from common aromatic diamines and 5‐(4‐benzoylamino‐1‐benzoylamino)isophthalic acid. The latter was synthesized from 5‐aminoisophthalic acid in a three‐step synthesis by successive incorporation of benzamido groups. The new polymers were characterized by NMR, DSC, TGA, and WAXD and the properties were compared to those of corresponding unsubstituted polyisophthalamides. All of the polymers were essentially amorphous and their Tgs were about 20°C higher than the reference polymers. Initial thermal decomposition temperatures ranged from 375 to 420°C. All of the polymers were soluble in aprotic polar solvents without added salts. Properties of particular note were: the water uptake, which was particularly high, ranging from 7.5 to 18.2%, and the temporary insolubilization in concentrated sulfuric acid of films of the polymers heated for a short time to ≥ 200°C. © 1995 John Wiley & Sons, Inc.
Synthesis of reactive copolyesters derived from isophthaloyl chloride, bisphenol a, and aliphatic diols with additional reactive groups
Authors: Wang Chonghui , Nakamura Shigeo
Published: April 2003

Copolycondensation of isophthaloyl chloride, bisphenol A, and aliphatic diols with additional reactive groups were performed in the presence of triethylamine by a trimethyl phosphate/cyclohexane organic/organic interfacial method. The composition of idol and bisphenol A residues in the resulting copolyesters is very close to that in the feed from the initial stage of reaction. The resulting copolyesters with reactive groups can be used for the preparation of various functional polymers. The mechanism of an organic/organic interfacial polycondensation was also discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and kinetics of polymerization of unsaturated monomers with OH groups in their structure. II. 3‐hydroxyneopentyl methacrylate
Authors: Iglesias M. T. , Guzmán J. , Riande E.
Published: April 2003

The synthesis of unsaturated monomers containing one or more hydroxyl groups by reaction between polyalcohols (number of OH, n≥2) and monoacid chlorides has been theoretically analyzed. The difficulties were shown involved in the preparation of these monomers with a high degree of purity even in the most favorable case of the completely substituted compound. The calculated mole fractions of the two monomers that can be obtained by reaction between neopentylglycol and methacryloyl chloride were compared with the experimental ones. Kinetic experiments of the polymerization of 3‐hydroxyneopentyl methacrylate and 2‐hydroxyethyl methacrylate were carried out at different temperatures in 1,4‐dioxane for the former monomer and dioxane and absolute ethanol for the latter. Dilatometric techniques and nonlinear least‐squares methods were used to obtain kinetic data and to determine the kinetic constants, respectively. In homogeneous solution the values of kp/k1/2t for the 3‐hydroxyneopentyl methacrylate and 2‐hydroxyethyl methacrylate was determined by 13C‐NMR spectroscopy and the molar fractions of tactic triads and dyads were calculated from different resonance signals. The polymers are predominantly syndiotactic and follow a Bernoullian distribution of tactic sequences. Finally, the glass transition temperatures of both polymers, determined calorimetrically, were 145 and 89°C, respectively. © 1995 John Wiley & Sons, Inc.
On the exotherm of polyacrylonitrile. II. Examination of deuterated polymers
Authors: Peebles L. H. , Snow A. W. , Peters W. C.
Published: April 2003

A series of α‐, β,β‐, and α,β,β‐deuterium‐labelled acrylonitrile monomers were prepared and polymerized. Secondary deuterium isotope effects on the polymerization and on the pyrolysis reactions that precede carbon fiber formation were observed. When deuterium is in the α‐position, the polymerization rate is greater and the molecular weight is higher. It is proposed that either the propagation rate constant or both that constant and the termination rate constant are increased on deuterium substitution. In differential scanning calorimetry, the polyacrylonitrile exotherm occurs at higher temperatures and is narrower when deuterium is substituted at the α‐position. On the other hand, the thermal gravimetric analysis activation energy for weight loss of polymer at temperatures below the acrylic exotherm is lower when deuterium is in the α‐position, relative to the α‐hydrogen polymers. As there is no correlation between the weight loss energy of activation and the various exotherm parameters, the weight loss energy of activation and the various exotherm parameters, the weight loss and exotherm are considered to be independent events. Examination of the distribution of deuterium substituted ammonia species evolved during 100–240°C thermal treatment of the α‐and β, β‐deuterated polyacrylonitriles provides a clear indication that both the α‐ and β‐positions are directly involved in hydrogen migration to nitrogen, but the mechanism of ammonia generation remains unclear. © 1995 John Wiley & Sons, Inc.
Polymerization of methyl methacrylate with cobalt acetylacetonate‐diethyl zinc catalyst system
Authors: Ravikumar L. , Ramarajan K. , Venkatarao K.
Published: April 2003

Polymerization of methyl methacrylate was studied with a cobalt acetylacetonate‐diethyl zinc catalyst initiator system in benzene medium at 40°C. When the stoichiometric ratio of Zn/Co is 2, the activity for polymerization is found to be maximum. The structure of the obtained polymethyl methacrylate is compared with that obtained using a free‐radical initiator such as benzoyl peroxide. The structure of polymer and the M̄w/M̄n values indicate that cobalt acetylacetonate‐zinc diethyl system has pronounced free‐radical characteristics. A suitable mechanism is proposed from the kinetic studies. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of polyimides endcapped with phenylethynylphthalic anhydride
Authors: Meyer G. W. , Glass T. E. , Grubbs H. J. , McGrath J. E.
Published: April 2003

The synthesis of high glass transition temperature (Tg > 300°C), amorphous, soluble, poly‐imide oligomers of controlled molecular weight endcapped with 4‐phenylethynylphthalic anhydride endcapping agent is described. The 4‐phenylethynylphthalic anhydride was employed to afford a higher curing temperature (380–420°C) which widens the processing window compared to unsubstituted acetylene‐endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester‐acid of various dianhydrides and aromatic diamines. A “ one‐pot” procedure utilizing NMP as the solvent and o‐dichlo‐robenzene as the azeotroping agent reproducibly produced fully imidized, but yet soluble wholly aromatic polyimides. Thermally cured samples were prepared with gel contents of up to 98% that displayed good solvent resistance. Glass transition temperatures comparable to high molecular weight linear analogs were produced. These polyimides also show excellent thermal stability as judged by thermogravimetric analysis (TGA). Model phenylethynyl imide compounds were synthesized and used to follow and elucidate the nature of the products formed from the phenylethynyl curing by using high temperature magic‐angle 13C nuclear magnetic resonance (MAS NMR). Preliminary results indicate that the cure reaction can be followed by MAS NMR. However, the nature of the products being formed during the curing process is difficult to determine by the solid‐state MAS NMR alone. Differential scanning calorimetry (DSC) data clearly show that the model system does indeed melt and displays a wide window before the strong cure exotherm is observed. © 1995 John Wiley & Sons, Inc.
Study on curing reaction of epoxy resin modified with prepolymers containing spiro orthocarbonate
Authors: Pan Caiyuan , Qi Longwu , Bai Ruke
Published: April 2003

Prepolymers were prepared by the reaction of 3,9‐dihydroxyethyl‐3′9′‐dibenzyl‐1,5,7,11‐tetraoxaspiro(5,5)undecane with 4,4′‐diphenylmethane diisocyanate (MDI) and 1,6‐hexa‐methylene diisocyanate (HDI). The number‐average molecular weights of the prepolymers can be controlled by changing the mole ratios of spiro compound and diisocyanates. Kinetic studies of the cure reaction for the epoxy resin system modified with or without prepolymers were followed by a HLX‐1 dynamic torsional vibration apparatus. The results indicated that gel time (tg) and activation energy (Ea) increased as the content of prepolymers in the epoxy resin system increased. A difference with the cure reaction of the pure epoxy resin, the second‐order reaction for the epoxy resin modified with the prepolymers, was obtained. Rate constants (k) of the cure reaction are 0.231 min−1 for the epoxy resin, and 0.312 min−1 for the modified epoxy resin. The mechanism of the cure reaction was discussed. © 1995 John Wiley & Sons, Inc.
Kinetics of amine‐cyclic anhydride reactions in moderately polar solutions
Authors: Padwa Allen R. , Sasaki Yoro , Wolske Kurt A. , Macosko Christopher W.
Published: April 2003

The validity of extrapolating the reactivity of low molar mass compounds in solution to the polymer‐analogous chemistry between polymer‐bound functionality is investigated for the reaction of primary amines with cyclic anhydrides in the moderately polar solvents, anisole and tetraethyleneglycol dimethylether. The kinetics of amic‐acid formation and imidization of polymeric and small molecule mixtures measured by Fourier‐Transform Infrared Spectroscopy at near‐ambient and elevated temperatures are compared. A Significant decrease in both reaction rates is observed upon changing the primary amine from aliphatic to benzylic, benzylic to 1,2‐diphenylethylamine, and 1,2‐diphenylethylamine to polystyrene‐bound 1,2‐diphenylethylamine. Reasons for the influence of polymer‐bound chemical functionality on the reaction rates for these amines are discussed. The imidization step is found to be rate limiting in the reaction of phthalic anhydride with benzylamine at the functional group concentrations reported (0.14M or less). © 1995 John Wiley & Sons, Inc.
Copolymerization of butadiene and styrene with a gadolinium tricarboxylate catalyst
Authors: Kobayashi Eiichi , Kaita Shojiro , Aoshima Sadahito , Furukawa Junji
Published: April 2003

Homo‐ and copolymerizations of butadiene (BD) and styrene (St) were carried out by gadolinium catalysts having various tricarboxylate ligands [Gd(OCOR)3: R = CH3, CH2Cl, CHCl2, CCl3, and CF3], to investigate the effects of ligands and discuss the cis polymerization mechanism. Polymerization of BD with Gd(OCOR)3—(i—Bu)3Al—Et2AlCl catalysts was carried out in hexane at 50°C. By each catalyst, poly(BD) having a high cis content (cis = 97–99%) in 22–85% yields for 2–24 h were obtained. The ligands with low pKa values increased the polymerization activity as follows: R of Gd(OCOR)3: CF3 > CCl3 > CHCl2 > CH2Cl ∼ CH3. On the other hand, in the polymerization of St or copolymerization of BD and St under similar conditions, the highest activity was attained by a Gd(OCOCCI3)3‐ based catalyst. The difference in the optimum ligand among the homo‐ and copolymerization of BD and St was discussed on the basis of energy levels of the catalysts. In the copolymers of BD and St, the cis‐1,4 content of the BD unit decreased with increasing St content. Furthermore, according to the diad analysis of copolymers (St content ∼ 14.5 mol %) by 13C NMR spectroscopy, the low cis value of the BD unit was observed in the St‐BD diad (cis/trans/vinyl = 24/53/23), while the high cis value of the BD unit remained in the BD‐BD diad (cis/trans/vinyl = 89/10/1). These results suggest that the terminal BD unit is controlled by the cis configuration by the coordination between the penultimate cis vinylene unit and the gadolinium metal catalyst, whereas the presence of the penultimate St unit interferes with cis polymerization of the terminal BD unit. The difference in the coordination mechanism in the course of polymerization between rare earth metal and transition metal catalysts such as the Ni(acac)2 and Co(acac)3‐based catalyst was also discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of polyimides derived from 1,7‐bis(4‐aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides
Authors: Yang Chin‐Ping , Lin Jiun‐Hung
Published: April 2003

The novel diamine, 1,7‐bis(4‐aminophenoxy)naphthalene (1,7‐BAPON), was synthesized and used to prepared polyimides. 1,7‐BAPON was synthesized through the nucleophilic displacement of 1,7‐dihydroxynaphthalene withp‐fluoronitrobenzene in the presence of K2CO3followed by catalytic‐reduction. Polyimides were prepared from 1,7‐BAPON and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that included ring‐opening polyaddition to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities of 0.74‐2.48 dL/g. Most of the polyimides formed tough, creasible films. These polyimides had glass transition temperatures between 247–278°C and their 10% weight loss temperatures were recorded in the range of 515–575°C in nitrogen atmosphere. © 1995 John Wiley & Sons, Inc.
Living cationic polymerization of isobutyl vinyl ether by the carboxyl group of the carbon black/zinc chloride initiating system
Authors: Yoshikawa Sachio , Nishizaka Rie , Oyanagi Ken'ichi , Tsubokawa Norio
Published: April 2003

The effect of zinc chloride (ZnCl2) on the cationic polymerization of isobutyl vinyl ether (IBVE) initiated by carboxyl groups on a carbon black surface was investigated. Although the polymerization of IBVE was initiated by carboxyl groups on the surface, the rate of polymerization was small and the molecular weight distribution (MWD) of poly IBVE was very broad. The rate of the polymerization was found to be drastically increased, and 100% monomer conversion was achieved in a short time by the addition of ZnCl2. The number‐average molecular weights (Mn) of the polyIBVE were directly proportional to monomer conversion in the polymerization initiated by the carbon black/ZnCl2 system. By addition of the monomer at the end of the first‐stage polymerization, the added monomer was smoothly polymerized at the same rate as in the first stage. The Mn of the polymer was in excellent agreement with the calculated value, assuming the polyIBVE chain forms per unit carboxyl group on the surface and MWD was narrow (Mw/Mn = 1.2 ∼ 1.3). Based on the results, it is concluded that carbon black/ZnCl2 system has an ability to initiate the living cationic polymerization of IBVE. Furthermore, it was found that polyIBVE was grafted onto the carbon black surface after the quenching of the living polymer with methanol. © 1995 John Wiley & Sons, Inc.
Phase separation of copolyurethanes: A study of annealing and slow solvent evaporation methods by FTIR
Authors: Gower L. A. , Lyman D. J.
Published: April 2003

Copolyether‐urethane‐ureas based on methylene bis(4‐phenylisocyanate), polypropylene glycol (or polytetramethylene glycol), and ethylene diamine showed improvement in packing order within the already present phases when subject to both thermal annealing and slow solvent evaporation techniques using glass as the casting substrate. However, formation of these copolymer films directly onto IR salt crystals led to major disturbances in the copolymer morphology due to the dissolving of inorganic salt into the polymer casting solution. These disturbances appear to be caused by a salt‐urea segment interaction. The urea amide I band (1635 cm−1) appears to be a sensitive indicator of such changes in these copolymers. © 1995 John Wiley & Sons, Inc.
Retardation of dibenzo polyether‐formaldehyde resin formation by alkali‐metal cations
Authors: Zhao Qiang , Bartsch Richard A.
Published: April 2003

Macrocyclic polyethers are well‐known complexing agents for alkali‐metal and alkaline earth‐metal cations. The influence of alkali‐metal cations upon the polycondensation rate of acyclic and cyclic dibenzo polyethers with formaldehyde in formic acid and alkali‐metal cation sorption by some of the resultant resins have been investigated. For certain dibenzo polyether and alkali‐metal cation combinations, polymer formation is markedly reduced. The alkali‐metal cation that provides the best fit for the macrocyclic polyether cavity produces the greatest retardation of polymer formation. It is proposed that metal ion complexation renders the dibenzo polyether monomer inert to polymerization under the reaction conditions. No template effect for alkali‐metal cation sorption by dibenzo polyether carboxylic acid resins was observed. © 1995 John Wiley & Sons, Inc.
Molecular engineering of liquid crystalline polymers by “living” polymerization. XXXII. Synthesis and “living” cationic polymerization of 3‐fluoro‐4′‐(ω‐vinyloxyalkoxy)‐4‐biphenylyl (2r,3s)‐2‐fluoro‐3‐methylpentanoate with undecanyl and octyl alkyl groups
Authors: Perce Virgil , Oda Hiroji
Published: April 2003

The synthesis and “living” cationic polymerization of 3‐fluoro‐4′‐(11‐vinyloxyundecany‐loxy)‐4‐biphenylyl (2R,3S)‐2‐fluoro‐3‐methylpentanoate (12‐11) and 3‐fluoro‐4′‐(8‐vi‐nyloxyoctyloxy)‐4‐biphenylyl (2R,3S)‐2‐fluoro‐3‐methylpentanoate (12‐8) are presented. Poly (12‐11)s and poly (12‐8)s with degrees of polymerization from 4.0 to 16.5 and poly‐dispersities ≤ 1.13 have been synthesized and characterized by differential scanning cal‐orimetry (DSC) and thermal optical polarized microscopy. Over the entire range of molecular weights poly (12‐11)s and poly (12‐8)s exhibit an enantiotropic SA and an unidentified SX phase. In addition, regardless of its molecular weight, poly (12‐8) exhibits a S*c phase in between the SA and Sx phases. Poly (12‐11) and poly (12‐8) show lower transition tem‐peratures and broader temperature ranges of all their mesophases as compared to the corresponding polymers without a fluorine atom on the biphenyl group. The role of the connecting group between the biphenyl and chiral group of the mesogenic unit on the phase behavior of these polymers is also discussed. Copolymers of 12‐8 with (2R,3S)‐2‐fluoro‐3‐methylpentyl 4′‐(11‐vinyloxyundecanyloxy)biphenyl‐4‐carboxylate (13‐11) {i.e., poly‐[(12‐8)‐co‐(13‐11)] (X/Y), where X/Y represents the molar ratio of monomer 12‐8 to monomer 13‐11} with DP of ca. 11 and polydispersities lower than 1.23 were also syn‐thesized and characterized. Their SA and S*c mesophases exhibit continuous dependences of composition and this support the assignment of the mesophases exhibited by poly (12‐8). © 1995 John Wiley & Sons, Inc.
Block copolymerization of alkoxyallenes by the living coordination system with a π‐allylnickel catalyst
Authors: Tomita Ikuyoshi , Abe Toru , Takagi Koji , Endo Takeshi
Published: April 2003

Block copolymers of alkoxyallenes were obtained in high yield by the two‐stage living coordi‐nation polymerization of two kinds of alkoxyallenes using an allylnickel catalyst. The resulting copolymers had narrow molecular weight distributions (∼ 1.1), regardless of the order of the monomer additions. When an alkoxyallene‐bearing hydrophilic substituent was used as a co‐monomer for the block copolymerization with that bearing a hydrophobic one, the resulting copolymer showed amphiphilic properties. For example, a block copolymer obtained by the copolymerization of n‐hexyloxyallene with diethylene glycol allenyl methyl ether was soluble in water as well as n‐hexane. © 1995 John Wiley & Sons, Inc.
Chemical modification of butyl rubber. III. Butyl rubber with D‐maltose derivative as pendant groups
Authors: Ikeda Yuko , Nakamura Yuka , Kajiwara Kanji , Kohjiya Shinzo
Published: April 2003

A new type of amphiphilic elastomer was synthesized, which consisted of butyl rubber and a D‐maltose derivative as a backbone and side groups, respectively. The synthesis was accomplished by the sequence of the three following reactions: (1) Hydroxyl groups of D‐maltonolactone were protected by a trimethylsilyl group. (2) The resulting maltonolactone derivative was subjected to a reaction with chemically modified butyl rubber having pendant amino groups. (3) The protecting trimethylsilyl groups on the maltose residues were removed by treating with tetra‐n‐butylammonium fluoride. This new amphiphilic elastomer behaved as a thermoplastic elastomer and showed good mechanical properties. The saccharide seg‐ments aggregated in the hydrophobic butyl rubber matrix to form a microphase‐separated structure, as confirmed by differential scanning calorimetry, transmission electron mi‐croscopy, small‐angle x‐ray scattering, and dynamic mechanical measurements. The ag‐gregated saccharide domains are estimated to function both as crosslinking sites and rein‐forcing fillers in the rubber matrix. © 1995 John Wiley & Sons, Inc.
Main chain liquid crystalline ionic polymers with thermotropic and lyotropic mesophases
Authors: Jegal J. G. , Blumstein A.
Published: April 2003

An ionogenic main chain liquid crystalline polymer was synthesized. In contrast to previous studies the charged sites were incorporated into the flexible spacer and not into the mesogenic group. This was done through quaternization of 1,2‐bis(4‐pyridylethane) with a biphenyl‐4,4′‐nonanoxytoluenesulphonate. The polymer displayed thermotropic and lyotropic me‐sophases. The thermotropic mesophase was smectic. Organic counterions such as meth‐ylsulfonates and p‐toluenesulfonates were found to be favorable to the development of mesophases, due to the increased solubility and lower isotropisation temperatures, when compared to bromide counterion containing polymers. Easy supercooling, dependence on thermal history, and the development of batonnet textures on cooling from the melt were also observed. © 1995 John Wiley & Sons, Inc.
Preparation of a novel HALS polypropylene stabilizer
Authors: Ekman Kenneth , Ekholm Lars , Näsman Jan H.
Published: April 2003

The radiation induced graft copolymerization of m‐isopropenyl‐α,α‐dimethyl benzyl iso‐cyanate (m‐TMI) and styrene onto polypropylene was carried out. The extent of grafting increased with increasing amount of styrene and with increased radiation dose. A graft load of 180% was obtained by immersing a 50 kGy pre‐irradiated film in a monomer solution containing 25 mol % m‐TMI and 75 mol % styrene. The graft copolymer is suitable for covalently binding nonpolymerizable stabilizers with a suitable nucleophilic moiety. In this work the isocyanate moiety of the graft copolymer was allowed to react with 4‐amino‐2,2,6,6‐tetramethyl piperidine, a hindered amine light stabilizer. Fourier trans‐formed infrared spectroscopy confirmed the formation of an urea moiety. © 1995 John Wiley & Sons, Inc.
Reversible photodimerization of coumarin derivatives dispersed in poly(vinyl acetate)
Authors: Chen Yun , Chou Cheng‐Fu
Published: April 2003

Four photoreactive coumarin derivatives were successfully synthesized from 7‐hydroxy‐coumarin and 7‐hydroxy‐4‐methylcoumarin, i.e., 7‐propionyloxy‐4‐methylcoumarin (M1), 7‐palmitoyloxy‐4‐methylcoumarin (M2), 7‐propionyloxycoumarin (M3), and 7‐palmitoy‐loxycoumarin (M4). Reversible photodimerization (350 or 300 nm) and photocleavage (254 nm) of these coumarin derivatives dispersed in poly(vinyl acetate) (PVAc) were investigated by tracing their UV absorbance variations at 310 nm. The M2 and M4 with long palmitoyl chain show much better photoreaction reversibility than M1 and M3 with short propionyl chain. Moreover, photodimerization rate (under 350 nm) of M2 is greater than 200 times of that of M1. This has been explained by the formation of suitable conformation for revers‐ible photodimerization due to the hydrophobic interactions. Photodimerization of M2 is ca. 3 times quicker than that of M4, indicating 4‐methyl substitution enhances pho‐todimerization. The influence of photodimerization wavelength (350 and 300 nm) and photosensitizer (benzophenone) have also been investigated in detail. © 1995 John Wiley & Sons. Inc.
Poly(Ether sulfone)s made from 4,4′‐dihydroxystilbene and 4,4′‐difluorodiphenylsulfone: Synthesis, crosslinking, and epoxidation with hydrogen peroxide
Authors: Gao Chunping , Hay Allan S.
Published: April 2003

High molecular weight polymers from trans‐4,4′‐dihydroxystilbene, bisphenols, and 4,4′‐difluorodiphenylsulfone were synthesized by a nucleophilic displacement reaction using DMAc as solvent in the presence of potassium carbonate. Characterization and crosslinking studies of these polymers were carried out by DSC, TGA, TMA, x‐ray diffraction, and solution and solid NMR. It was found that all polymers can be crosslinked to some extent on heating to 350°C. We also studied the epoxidation of these polymers with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate (3—) as the catalyst in a biphasic system. The epoxidized polymers are thermally cross‐linkable. Very efficient crosslinking was obtained by heating the epoxidized polymers at 350°C under nitrogen. © 1995 John Wiley & Sons, Inc.
Photocrosslinking of functionalized rubber. II. Photoinitiated cationic polymerization of epoxidized liquid natural rubber
Authors: Decker C. , Le Xuan H. , Thi Viet T. Nguyen
Published: April 2003

Low molecular weight epoxidized natural rubber has been crosslinked within seconds by UV irradiation in the presence of a triarylsulfonium salt. The photoinitiated cationic ring‐opening polymerization was studied quantitatively by infrared spectroscopy and shown to proceed with surprisingly long kinetic chains in such solid medium. The high conversion (60%) needed for complete insolubilization, together with the presence of tetrahydrofuran structures, argue in favor of an intramolecular polymerization process involving neighboring epoxy groups. The photoinitiator concentration has a strong influence on the rate and extent of the reaction, as well as on the depth of cure profile. Because of an efficient dark process, close to 100% conversion was reached upon storage of the irradiated elastomer at ambient, with a concomitant increase of the gel fraction and the polymer hardness. The grafting of pendent acrylate groups onto the polymer chain leads to a three‐fold decrease of the initial rate of polymerization of the epoxide. The photocuring of natural rubber bearing both epoxy and acrylate groups generates a dual polymer network which combines the properties of the two moieties. © 1995 John Wiley & Sons, Inc.
Olefin terpolymerizations. III. Symmetry, sterics, and monomer structure in ansa‐zirconocenium catalysis of EPDM synthesis
Authors: Yu Zhengtian , Marques Maria , Rausch Marvin D. , Chien James C. W.
Published: April 2003

Ethylenebis (η5‐fluorenyl) zirconium dichloride (1) and rac‐dimethylsilylene bis (1‐η5‐in‐denyl) zirconium dichloride (2) were activated with methylaluminoxane (MAO) to catalyze ethylene (E) propylene (P) copolymerizations. The former produces high MW copolymer at 20°C rich in ethylene with reactivity ratio values of rE = 1.7 and rP <0.01, whereas the latter produces lower MW random copolymers with rE = 1.32 and rp = 0.36. Ethylidene norbornene (ENB) complexes with 1/MAO but does not undergo insertion in the presence of E and P. In contrast, 2/MAO catalyzes terpolymerization incorporating 9‐15 mol % of ENB with slightly lower MW and activity than the corresponding copolymerizations. In comparison, 1,4–hexadiene was incorporated by 2/MAO with much lower A and MW. Terpolymerizations were also conducted with vinylcyclohexene using both catalyst systems. The steric and electronic effects in these processes were discussed. © 1995 John Wiley & Sons, Inc.
Synthesis and degradabilities of polyesters from 1,4:3,6‐dianhydrohexitols and aliphatic dicarboxylic acids
Authors: Okada Masahiko , Okada Yasunari , Aoi Keigo
Published: April 2003

Six different polyesters (6a–6c and 7a–7c) were prepared by the bulk polycondensations of the respective combinations of 1,4:3,6‐dianhydro‐D‐glucitol (3) and 1,4:3,6‐dianhydro‐D‐mannitol (4) with succinyl dichloride (5a), glutaryl dichloride (5b), and adipoyl dichloride (5c) at 140–180°C. Polyesters having number average molecular weights up to 2.6 ×104 were obtained in high yields. Only polyester 7a based on 4 and 5a was partially crystalline, whereas all the other polyesters were amorphous. Thin films of these polyesters except that of 7a were spontancously hydrolyzed in a neutral phosphate buffer solution at 50°C, whereas they were reluctant to be hydrolyzed at 27°C. The polyesters were more or less degraded at 27°C by treatment with an activated sludge or by prolonged burial in soil. © 1995 John Wiley & Sons, Inc.
Poly(diarylsilmethylene)s, I. Synthesis and characterization
Authors: Ogawa Takuya , Tachikawa Mamoru , Kushibiki Nobuo , Murakami Masashi
Published: April 2003

Poly(diarylsilmethylene)s with phenyl or tolyl substituents on Si atoms were synthesized by ring‐opening polymerization of corresponding 1,1,3,3‐tetraaryl‐1,3‐disilacyclobutanes, and were characterized by means of DSC, x‐ray diffraction and melt viscosity measurements. Three preparative routes including catalytic and noncatalytic polymerization methods were examined to see differences in properties of the resulting polymers. The polymers thus obtained were crystalline and soluble in limited solvents such as diphenyl sulfone at tem‐peratures above 250°C. Poly(diphenylsilmethylene) exhibited a melting temperature of about 350°C, whereas those of polymers with tolyl groups were observed in a temperature range between 310 and 330°C. The melt viscosity of the poly(diarylsilmethylene)s was measured to obtain insight into the molecular weights of the polymers, and the results indicated that the molecular weights are modifiable by varying the monomer‐to‐catalyst ratio when solution polymerization is employed. The DSC and x‐ray studies were also carried out with focusing on the melting and crystallization behavior of these polymers. © 1995 John Wiley & Sons, Inc.
Radical polymerization behavior of ethyl ortho‐formylphenyl fumarate involving intramolecular hydrogen abstraction
Authors: Sato Tsuneyuki , Shimooka Sumio , Seno Makiko , Tanaka Hitoshi
Published: April 2003

The radical polymerization behavior of ethyl ortho‐formyl‐phenyl fumarate (EFPF) using dimethyl 2,2′‐azobisisobutyrate (MAIB) as initiator was studied in benzene kinetically and ESR spectroscopically. The polymerization rate (Rp) at 60°C was given by Rp = k[MAIB]0.76[EFPF]0.56. The number‐average molecular weight of poly(EFPF) was in the range of 1600–2900. EFPF was also easily photopolymerized at room temperature without any photosensitizer probably because of the photosensitivity of the formyl group of monomer. Analysis of 1H− and 13C‐NMR spectra of the resulting polymer revealed that the radical polymerization of EFPF proceeds in a complicated manner involving vinyl addition and intramolecular hydrogen‐abstraction. The polymerization system was found to involve ESR‐observable poly(EFPF) radicals under the actual polymerization conditions. ESR‐determined rate constant (2.4–4.0 L/mol s) of propagation at 60°C increased with decreasing monomer concentration, which is mainly responsible for the observed low de‐pendency of Rp on the EFPF concentration. Copolymerizations of EFPF with some vinyl monomers were also examined. © 1995 John Wiley & Sons, Inc.
Electrical conductivity of thermally degraded poly(vinyl chloride)–polyacrylonitrile blends
Authors: Chatterjee Nandini , Palit Sunanda K. , Maiti Mrinal M.
Published: April 2003

Finely powdered blends of poly(vinyl chloride) (PVC) and polyacrylonitrile (PAN) have been thermally degraded at 275°C for 24 h in an inert atmosphere to effect complete de‐hydrochlorination of PVC to a conjugated polyene structure and simultaneous internal polymerization of nitrile groups in PAN to a conjugated polyimine sequence. The room temperature d.c. conductivity of the degraded blends showed clear synergistic behavior. A maximum conductivity has been observed with a blend of 60 PAN/40 PVC which is about 4 orders of magnitude over the linearly weighted average conductivity of the individual degraded homopolymers. The results have been interpreted in terms of a possible donor‐acceptor interaction between the degraded homopolymers leading to mutual doping and, hence, an enhanced electrical conductivity. © 1995 John Wiley & Sons, Inc.
A Reductive homo‐coupling polymerization of aromatic diisocyanates promoted by samarium iodide
Authors: Wang Jia , Nomura Ryoji , Endo Takeshi
Published: April 2003

The selective reductive homo‐coupling polymerization of aromatic diisocyanates via one‐electron transfer promoted by samarium iodide in the presence of hexamethylphosphoramide (HMPA) produced the corresponding poly(oxamide)s (1) nearly quantitatively. The ob‐tained polymers were insoluble in common organic solvents. The alkylation of 1 with methyl iodide or allyl bromide in the presence of potassium tert‐butoxide provided the highly soluble alkylated polymer in good yields. In either case, the alkylation was almost complete, and both N‐and O‐alkylation proceeded. The ratio of N‐and O‐methylation was found to be 64 : 36 by 1H‐NMR spectrum, and that of N‐ and O‐allylation was 3 : 1 from 13C‐NMR analysis. The present polymerization system could be applied to a variety of diisocyanates, including diphenylmethanediisocyanate (MDI), tolylene 2,6‐diisocyanate (TDI), 2,6‐naphthyl diisocyanate (NDI) and o‐tolidine diisocyanate (TODI). The molecular weights of the polymers were estimated by GPC and found to be 2000–9000. The TGA measurement of the corresponding polymers showed Td10 at 248–320°C. © 1995 John Wiley & Sons, Inc.
Liquid crystalline copolymers containing electron donor and acceptor mesogens with a chiral group in the spacer unit
Authors: Kosaka Yozo , Uryu Toshiyuki
Published: April 2003

Side‐chain liquid crystalline polymers containing both mesogenic (carbazolylmethylene)aniline and (4′‐nitrobenzylidene)aniline units with various spacer groups were prepared to examine effects of the structure of spacer groups on the liquid crystalline properties. The copolymer containing (R)‐(+)‐2‐methylpropylene as a chiral group in the spacer unit induced a smectic phase; the copolymer with a trimethylene spacer of similar length to the chiral spacer exhibited a nematic phase. Smectic phases were observed for the copolymer containing the chiral spacer group when the proportion of the carbazolyl group was in the range of 0.55–0.88. For example, the copolymer with the proportion of the carbazolyl group of 0.68 expressed the smectic phase from 88° to 167°C. This isotropic temperature was 37° higher than the calculated value (130°C) based on an assumed copolymer composition without the electron donor–acceptor interaction. Thus, it is assumed that for the chiral copolymer containing both electron donor and acceptor groups, the thermal stability and the induction of the smectic phase were caused by both the electron donor–acceptor interaction and the existence of the chiral group in the spacer unit. © 1995 John Wiley & Sons, Inc.
Influence of the physical characteristics of the polymer on the glass transition of various chemically modified PVCs
Authors: Hidalgo Manuel , Mijangos Carmen
Published: April 2003

Vinylchloride–vinylthiocresol and vinylchloride–vinylthionaphthol copolymers of various compositions were prepared by the substitution reaction of PVC with sodium thiocresol and sodium thionaphthol, respectively, in different solvents and at different temperatures. The variation of the glass transition temperature of these copolymers with chemical com‐position does not follow the Flory–Fox equation, but is found to depend on the solvent and the temperature at which the copolymer is obtained. The comonomer sequence distribution and stereosequence content of the above copolymers, and those of vinylchloride–vinyl‐thiobenzene copolymer, were determined by 1H‐ and 13C‐NMR spectroscopy. The depen‐dence of comonomer distribution and stereoregularity content with chemical composition for the three series of copolymers, prepared in different solvents and temperatures, are similar. The Tg deviations for the three series of copolymers were attributed to the con‐tribution of physical characteristics of the PVC structure, originating from polymer–solvent interactions. © 1995 John Wiley & Sons, Inc.
Preparation of poly(vinyl chloride) latexes by polymerization of stabilized monomer droplets
Authors: Sæthre Bård , Mørk Preben C. , Ugelstad John
Published: April 2003

Poly(vinyl chloride) latexes have been prepared by polymerization in micron and submicron sized monomer droplets. Monomer emulsions with excellent long time stability were obtained by diffusional swelling of vinyl chloride monomer into preformed, stable polydisperse pre‐emulsions of water‐insoluble oils or monodisperse, oligomer styrene seed particles. It was found that the size and size distribution of the final latex particles were determined by those of the parent monomer emulsions. Except for the secondary particles formed during polymerization, the size and size distributions of the latex particles were found to be com‐parable to those of the monomer emulsions employed, indicating a complete nucleation of the parent emulsion droplets. The extent of secondary particle formation was found to be very dependent upon the emulsifier concentration as well as on the type and amount of initiator used. © 1995 John Wiley & Sons, Inc.
Preparation of colored poly(styrene‐co‐butyl methacrylate) micrometer size beads with narrow size distribution by dispersion polymerization in presence of dyes
Authors: Horák Daniel , Švec František , Fréchet Jean M. J.
Published: April 2003

The preparation of monodisperse polymer particles formed by a dispersion copolymerization of a system containing styrene, butyl methacrylate, and nonpolymerizable dyes has been studied. Both the polarity of the ethanol–water dispersion medium and the polymerization rate were found to have a significant effect on the particle size. Experimental conditions have been determined that enable the preparation of colored beads having a narrow size distribution. While the benzoyl peroxide initiated polymerization is seriously inhibited by the presence of dyes, polymerization with azobisisobutyronitrile in presence of the black dye Nigrosin affords monodisperse beads in a high yield. © 1995 John Wiley & Sons, Inc.
Expression pattern of mouse homolog of prostate‐specific membrane antigen (FOLH1) in the transgenic adenocarcinoma of the mouse prostate model
Authors: Schmittgen Thomas D. , Zakrajsek Brian A. , Hill Richard E. , Liu Qian , Reeves Jerry J. , Axford Paul D. , Singer Michael J. , Reed Michael W.
Published: April 2003

BACKGROUND

Prostate specific membrane antigen (PSMA) is expressed on the plasma membrane of normal prostate and in primary and metastatic prostate cancer in humans. Recently, a mouse homolog of PSMA (FOLH1) was identified that shares an 85% sequence homology with human PSMA. The transgenic adenocarcinoma of the mouse prostate (TRAMP) model displays spontaneous tumor development with age and metastasizes to tissues similar to human prostate cancer. This study characterized the expression of Folh1 in the TRAMP model to determine if the TRAMP would be a useful model system to evaluate PSMA‐directed targeting strategies.

METHODS

A sensitive, real‐time quantitative PCR assay was developed to measure Folh1 cRNA copy number in various tissues of 30–32‐week‐old TRAMP+ and age‐matched, nontransgenic controls (TRAMP−).

RESULTS

Of the tissues studied, the highest expression of Folh1 was observed in the kidney and brain of both TRAMP+ and TRAMP− mice. Low levels of Folh1 cRNA (1–2 copies/ng total RNA) were detected in the tumor and lymph nodes of TRAMP + mice and in the seminal vesicles and lung of the TRAMP + and TRAMP− mice. The expression of Folh1 mRNA was sixfold higher in the prostate of 32‐week‐old TRAMP− mice compared to the tumor of 32‐week‐old TRAMP + mice. The rank order of the Folh1 expression in the tissues studied was kidney > brain > prostate > tumor > lymph nodes > lung > seminal vesicles > liver. Folh1 mRNA was undetectable in the bone marrow of both TRAMP+ and TRAMP− mice. Folate hydrolase activity assayed in the kidney, brain, lung, and liver paralleled the expression of Folh1 mRNA in these tissues.

CONCLUSIONS

We demonstrate that Folh1 is expressed at very high levels in some normal mouse tissues including the prostate gland and that the expression is not upregulated in the tumor of 32‐week‐old TRAMP + mice. Prostate 55: 308–316, 2003. © 2003 Wiley‐Liss, Inc.
Inhibition of proliferation of PC3 cells by the branched‐chain fatty acid, 12‐methyltetradecanoic acid, is associated with inhibition of 5‐lipoxygenase
Authors: Yang Peiying , Collin Peter , Madden Timothy , Chan Diana , Sweeney‐Gotsch Bridget , McConkey David , Newman Robert A.
Published: April 2003

Background

Branched‐chain fatty acids or fatty alcohols have been reported to possess anti‐tumor activity in various tumor models. Here we study 12‐methyltetradecanoic acid (12‐MTA), a branched‐chain fatty acid, isolated from a sea cucumber extract, on the growth of prostate cancer cells and investigate the underlying mechanisms of its effect.

Methods

12‐MTA was evaluated by MTT assay for its ability to inhibit cell proliferation in various cancer types. The ability of 12‐MTA to induce apoptosis of PC3 cells was examined by morphologic changes, propidium iodide (PI) staining, and caspase‐3 activation. Furthermore, alteration of eicosanoid metabolism by 12‐MTA was examined in PC3 and RBL‐1 cells and in purified lipoxygenase (LOX) and cyclooxygenase (COX) enzymes.

Results

12‐MTA inhibited proliferation of various cell lines, with IC ranging from 17.99 to 35.44 μg/ml. PI staining clearly showed that 12‐MTA caused PC3 cell death through induction of apoptosis. At 50 μg/ml, 12‐MTA increased caspase‐3 activity four to seven‐fold compared with that in control cells. Examination of cellular arachidonate metabolism showed that at 25 μg/ml, 12‐MTA reduced the level of 5‐hydroxyeicosatetraenoic acid (5‐HETE) by 45%. Furthermore, exogenous 5‐HETE protects PC3 cells from 12‐MTA induced cell death.

Conclusions

12‐MTA inhibited proliferation of cancer cells via apoptosis, in which caspase‐3 may play a role. At relevant concentrations, 12‐MTA can selectively inhibit the formation of 5‐HETE, a metabolite of 5‐lipoxygenase. This agent may be a novel adjunctive therapy for selected malignancies including prostate cancer. Prostate 55: 281–291, 2003. © 2003 Wiley‐Liss, Inc.
Jun Dimerization Protein 2 (JDP2), a Member of the AP-1 Family of Transcription Factor, Mediates Osteoclast Differentiation Induced by RANKL
Authors: Kawaida Reimi , Ohtsuka Toshiaki , Okutsu Junichi , Takahashi Tohru , Kadono Yuho , Oda Hiromi , Hikita Atsuhiko , Nakamura Kozo , Tanaka Sakae , Furukawa Hidehiko
Published: April 2003

Osteoclasts are multinucleated cells that resorb bones, and are derived from hematopoietic cells of the monocyte/macrophage lineage. The receptor activator of NF-κB ligand (RANKL, also called ODF/TRANCE/OPGL) stimulates both osteoclast differentiation from osteoclast progenitors and activation of mature osteoclasts. To identify genes responsible for osteoclast differentiation, we used a molecular indexing technique. Here, we report a clone of one of these genes whose transcription is induced by soluble RANKL (sRANKL) in both the RAW264.7 cells of the mouse macrophage cell line and the mouse primary bone marrow cells. The predicted protein was found to be a mouse homologue of Jun dimerization protein 2 (JDP2), a member of the AP-1 family of transcription factors, containing a basic region-leucine zipper motif. Transient transfection experiments revealed that overexpression of JDP2 leads to activation of both tartrate-resistant acid phosphatase (TRAP) and cathepsin K gene promoters in RAW264.7 cells. Infection of mouse primary bone marrow cells with retroviruses expressing JDP2-facilitated sRANKL-mediated formation of TRAP-positive multinuclear osteoclasts. Importantly, antisense oligonucleotide to JDP2 strongly suppressed sRANKL-induced osteoclast formation of RAW264.7 cells. Our findings suggest that JDP2 may play an important role in the RANK-mediated signal transduction system, especially in osteoclast differentiation.