bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of [o‐(trimethylgermyl)phenyl] acetylene and polymer characterization
Authors: Mizumoto Tomohiro , Masuda Toshio , Higashimura Toshinobu 
Published: April 2003

Abstract[o‐(Trimethylgermyl)phenyl]acetylene was polymerized in the presence of WCl6, W(CO)6‐hv, etc., to give polymers whose weight‐average molecular weights reached ca. 7.0 X 105 at the highest. When the MoOCl4‐n‐Bu4Sn‐EtOH (1 : 1 : 1) catalyst was used, the polydispersity ratio of the polymer obtained was 1.08, and the number‐average molecular weight increased in direct proportion to monomer conversion; these indicate that this polymerization is a living polymerization. The polymer had the structure  [CHC(C6H4‐o‐GeMe3)]n  and was a dark purple solid (λmax = 551 nm, εmax = 6100 M‐1 cm‐1 in THF) soluble in organic solvents such as toluene and chloroform. The onset temperature of weight loss of the polymer in TGA in air was ca. 230°C, and the glass transition temperature was above 180°C. The Po2 of the present polymer is 105 barrers—larger than the value of natural rubber and fairly close to that of poly(dimethylsiloxane). © 1993 John Wiley & Sons, Inc.
Synthesis of novel organic oligomers containing SiH bonds
Authors: Iwahara T. , Kusakabe M. , Chiba M. , Yonezawa K. 
Published: April 2003

AbstractSeveral organic oligomers (Mw = 103–104 order) containing SiH bonds of the general formula 1 have been successfully synthesized by platinum‐catalyzed partial hydrosilylation reaction of an allyloxy (or an allyl carbonate) end‐blocked linear organic oligomer 2 with 2,4,6,8‐tetramethylcyclotetrasiloxane, [CH3(H)SiO]4 (3) (hereafter called hydrocyclotetrasiloxane). 1H‐NMR spectroscopy confirmed the introduction of hydrocyclotetrasiloxane moiety into the oligomers through SiC linkage by hydrosilylation reaction. 13C‐NMR analysis revealed that the cyclic structure of the starting hydrocyclotetrasiloxane 3 was retained intact in product 1. As the precursor for 1, allyloxy (or allyl carbonate) end‐blocked oligomers 2 could be prepared from hydroxyl‐terminated oligomers 4. The storage stability of product 1 was significantly influenced by the platinum catalyst still remaining in it. The poor stability was improved by decreasing the amount of the platinum catalyst and/or by adding coordinating compounds. As a result, an excellent stability of product 1 was obtained. © 1993 John Wiley & Sons, Inc.
Studies on the thermotropic liquid crystalline polycarbonates. III. Synthesis and properties of fully aromatic liquid crystalline polycarbonates
Authors: Sun Shih‐Jien , Chang Teh‐Chou 
Published: April 2003

AbstractFour series of fully aromatic thermotropic liquid crystalline polycarbonates were prepared by melt polycondensation from various novel phenylene diphenyl dicarbonates with monomers, such as hydroquinone, methylhydroquinone, chlorohydroquinone, resorcinol, bisphenol A, 4,4′‐dihydroxydiphenylsulfone, or phenylhydroquinone, respectively. The thermotropic liquid crystalline properties were studied by polarizing microscope with a heating stage, differential scanning calorimeter (DSC), and wide‐angle x‐ray diffraction (WAXD). It was found that the nonlinearity of the carbonate group was compensated by resorcinol (1,3‐phenylene unit), a bent shape unit. Nematic melts were found for the resulting polycarbonates. © 1993 John Wiley & Sons, Inc.
Regioselective hydrosilations. II. The synthesis of silicon–hydrogen functional compounds
Authors: Crivello J. V. , Bi Daoshen 
Published: April 2003

AbstractThe discovery that the rhodium‐catalyzed hydrosilation of unsaturated epoxides with compounds containing two SiH functional groups proceeds in a discrete, stepwise fashion, has made possible the synthesis of a series of interesting compounds containing both SiH and epoxy groups in the same molecule. These compounds can be used both as an interesting new class of epoxy monomers as well as intermediates for the preparation of a wide variety of novel monomers which incorporate epoxide as well as other types of polymerizable functional groups © 1993 John Wiley & Sons, Inc.
Crosslinking of styrene–butadiene rubber with 1,2‐bis(benzocyclobutenyl)ethane
Authors: Fishback Thomas L. , Farona Michael F. 
Published: April 2003

Abstract1,2‐Bis(benzocyclobutenyl)ethane (BBCB) was used as a thermally activated crosslinking agent in styrene–butadiene rubber (SBR), both in the raw and carbon black‐filled materials. Diels–Alder crosslinking reactions occurred to a significant degree, despite the lack of substituents of opposing electronic effects. The reaction is free of toxic crosslinking promoters and evolved by‐products. Various physical properties such as ultimate elongation, tensile strength, and modulus were measured and compared to those properties of a sulfur‐cured sample of SBR. Linear relationships were found between the amount of BBCB present and the modulus of the materials, as well as the amount of BBCB and solvent uptake in swell tests. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of poly(hydroxyurethane)s
Authors: Kihara Nobuhiro , Endo Takeshi 
Published: April 2003

AbstractBis(cyclic Carbonate)s 1 were prepared by the reaction of bis(epoxide)s and atmospheric pressure of CO2 in the presence of sodium iodide and triphenylphosphine as catalysts at 100°C in high yield. Polyaddition of 1 and hexamethylenediamine (2a) or dodecamethylenediamine (2b) in dimethylsulfoxide or N,N‐dimethylacetamide (DMAc) at 70 or 100°C for 24 h afforded corresponding poly(hydroxyurethane)s with M̄n 20,000–30,000. When ethylenediamine (2c) or 1,3‐propanediamine (2d) was used as a diamine, poly(hydroxyurethane)s with lower molecular weight were obtained. The presence of water, methanol, or ethyl acetate in the solvent had little effect on the M̄n of the polymer obtained, because of the high chemoselectivity of the reaction of the five‐membered cyclic carbonate and amine. Polyaddition of bis(cyclic carbonate) bearing ester groups and 2a also afforded the corresponding poly(hydroxyurethane) without aminolysis of the ester groups. Poly(hydroxyurethane) 3 obtained from the bis(cyclic carbonate) derived from bisphenol A was less soluble in organic solvents than model polyurethane 8 having no hydroxy groups obtained from 4,4′‐isopropylidenebis(2‐hydroxyethoxybenzene) and hexamethylene diisocyanate, and was thermally stable as well as 8.3 easily undertook crosslinking at room temperature by the treatment with hexamethylene diisocyanate or aluminium triisopropoxide in DMAc or tetrahydrofuran. The gel crosslinked by aluminium triisopropoxide regenerated the original polymer at room temperature by treatment with 1.5 equiv of 1.2M HCl in N‐methylpyrollidinone for 1 h. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new polyimides derived from 1,5‐bis(4‐aminophenoxy)naphthalene and aromatic tetracarboxylic dianhydrides
Authors: Yang Chin‐Ping , Chen Wen‐Tung 
Published: April 2003

AbstractNovel aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from 1,5‐bis(4‐aminophenoxy)naphthalene (APN) and various aromatic tetracarboxylic dianhydrides by the usual two‐step procedure that included ring‐opening polyaddition in a polar solvent such as N,N‐dimethylacetamide (DMAc) to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities between 0.72 and 1.94 dL/g, depending on the tetracarboxylic dianhydrides used. Excepting the polyimide IVb obtained from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), all other polyimides formed brown, flexible, and tough films by casting from the poly(amic acid) solutions. The polyimide synthesized from BPDA was characterized as semicrystalline, whereas the other polyimides showed amorphous patterns as shown by the x‐ray diffraction studies. Tensile strength, initial moduli, and elongation at break of the APN‐based polyimide films ranged from 105–135 MPa, 1.92–2.50 GPa, and 6–7%, respectively. These polyimides had glass transition temperatures between 228 and 317°C. Thermal analyses indicated that these polymers were fairly stable, and the 10% weight loss temperatures by TGA were recorded in the range of 543–574°C in nitrogen and 540–566°C in air atmosphere, respectively. © 1993 John Wiley & Sons, Inc.
Regioselective oxidative polymerization of 1,5‐dihydroxynaphthalene catalyzed by bilirubin oxidase in a water–organic solvent mixed solution
Authors: Wang Lili , Kobatake Eiry , Ikariyama Yoshihito , Aizawa Masuo 
Published: April 2003

AbstractBilirubin oxidase (EC1.11.1.7) was used to catalyze the oxidative polymerization of 1,5‐dihydroxynaphthalene to its polymer in a mixed solvent composed of dioxane, ethyl acetate, and acetate buffer. In an aqueous solution, the enzymatic oxidative polymerization hardly occurred and resulted in negligible yield mainly due to the poor solubility of 1,5‐dihydroxynaphthalene. In the mixed solvent the conversion proceeded with a yield of ca. 70%. The polymer yield was studied with respect to reaction time and solvent components. Elemental analysis, UV‐visible, fluorescent, and FT‐IR spectroscopic analyses, proton NMR and electrochemical studies, and solubility in various organic solvents revealed that 1,5‐dihydroxynaphthalene is polymerized by the CC coupling. The molecular weight of the polymeric products solubilized with DMF varied from low molecular weight product to high molecular weight polymer. From the chromatographic studies, the organic solvent–insoluble residue was suggested to be highly polymerized material. Based on these findings a possible mechanism for enzymatic polymerization of 1,5‐dihydroxynaphthalene is presented: less stable intermediates produced enzymatically from 1,5‐dihydroxynaphthalene undergo coupling and polymerization to ortho‐1,5‐dihydroxynaphthalene polymer, thereby resulting in a regioselective polymerization of 1,5‐dihydroxynaphthalene. © 1993 John Wiley & Sons, Inc.
Main‐chain, syndioregic, high‐glass transition temperature polymer for nonlinear optics: Synthesis and characterization
Authors: Stenger‐Smith J. D. , Henry R. A. , Hoover J. M. , Lindsay G. A. , Nadler M. P. , Nissan R. A. 
Published: April 2003

AbstractA new main‐chain syndioregic (head‐to‐head) NLO polymer was synthesized. The glass transition temperature of high molecular weight polymer was found to be 208°C, and the polymer has minimal weight loss at temperatures to at least 250°C owing to the incorporation of hydrogen bonding moieties and rigid bridging groups. The polymer was further characterized using nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The study of the nonlinear optical properties of this polymer are in progress. © 1993 John Wiley & Sons, Inc.
Calorimetric monitoring of emulsion copolymerization reactions
Authors: Urretabizkaia Agustín , Sudol E. David , El‐Aasser Mohamed S. , Asua Josée M. 
Published: April 2003

AbstractAn approach for monitoring both the overall conversion and the cumulative copolymer composition in emulsion copolymerization systems via calorimetric measurements was developed. The approach was checked by carrying out batch emulsion copolymerizations of methyl methacrylate/n‐butyl acrylate, n‐butyl acrylate/vinyl acetate, and methyl methacrylate/vinyl acetate and comparing calorimetric based estimations with off‐line determinations of both the overall conversion and the cumulative copolymer composition. A good agreement was achieved for most of the cases studied. © 1993 John Wiley & Sons, Inc.
One‐phase supported titanium‐based catalysts for polymerization of ethylene. III. ESR spectra of the ternary system Sio2—R3Al—TiCl4
Authors: Věčorek P. , Šindelář P. , Černošková E. , Holeček J. 
Published: April 2003

AbstractThe ternary catalyst systems based on activated silica, aluminum alkyl, and titanium tetrachloride were polymerized in an ethylene gas‐phase polymerization process, and further studied using ESR spectroscopy. Two types of titanium (III) ESR‐active centers were observed and a linear dependence between the concentration of that characterized by a rhombic anisotropic signal with g1 = 1.962, g2 = 1.945, and g3 = 1.913 values and catalyst productivity was found. © 1993 John Wiley & Sons, Inc.
New polymer syntheses. LXVI. Copolyester of 4‐hydroxybenzoic acid and 3‐(4'‐hydroxyphenoxy)benzoic acid or 4‐(3'‐hydroxyphenoxy)benzoic acid
Authors: Kricheldorf Hans R. , Döring Volker , Schwarz Gert 
Published: April 2003

AbstractCopolyesters of 4‐hydroxybenzoic acid (HBA) and 3‐(4'‐hydroxyphenoxy)benzoic acid were prepared by two different procedures. Either the acetyl derivatives were polycondensed in bulk at temperatures up to 300°C or they were polycondensed in an inert reactions medium (Marlotherm‐S) at 340°C. Two analogous series of copolyesters were synthesized from 4‐acetoxybenzoic acid (4‐HBA) and 4‐(3'‐acetoxyphenoxy)benzoic acid. The copolyesters were characterized by elemental analyses, inherent viscosities, 1H‐ and 13C‐NMR spectroscopy, WAXS and DSC measurements, and by optical microscopy. All copolyesters synthesized in solution were highly crystalline materials which were neither meltable nor soluble. Part of the copolyesters prepared by polycondensation in bulk were semi‐crystalline, meltable, and soluble. The copolyester derived from 3‐(4'‐hydroxyphenoxy)benzoic acid proved to be thermotropic forming a nematic melt, whereas the isomeric copolyesters of 4‐(3'‐hydroxyphenoxy)benzoic acid only formed isotropic melts. © 1993 John Wiley & Sons, Inc.
Mechanisms and kinetics of polymerization of thermoplastic polyimides. II. Study of “bridged” dianhydride/aromatic amine systems
Authors: Grenier‐Loustalot Marie‐Florence , Joubert Fréderic , Grenier Philippe 
Published: April 2003

AbstractThe aim of the present work was to identify and follow the main and side reactions involved in the ring dehydration of amic acid prepared from “bridged” dianhydrides whose central substituent is an electron acceptor or donor, and an aromatic diamine. Several isomeric structures may appear as a result of the opening reactivity and selectivity of anhydride groups towards the aromatic amine. Reaction mechanisms and kinetics were thus studied in solvent phase with HPLC and 13C‐NMR and in solid molten phase by FTIR and solid 13C‐NMR. The experimental conditions (liquid and solid) and the structure of the products (type of central substituent) affecting the mechanisms and kinetics of the reactions were noted. © 1993 John Wiley & Sons, Inc.
γ‐poly(glutamic acid) as an initiator of cationic polymerization of N‐vinylcarbazole and N‐vinyl‐2‐pyrrolidone
Authors: Tsubokawa Norio , Inagaki Masatoshi , Kubota Hidetoshi , Endo Takeshi 
Published: April 2003

AbstractThe cationic polymerization of vinyl monomers initiated by biosynthesized γ‐poly(glutamic acid) (γ‐PGA) powder surface was carried out in a heterogeneous system. It was found that the polymerization of N‐vinylcarbazole (NVC) and N‐vinyl‐2‐pyrrolidone (NVPD) is initiated by γ‐PGA powder. The grafting of polymers onto γ‐PGA surface was scarcely observed. The apparent activation energy of the polymerization of NVC and NVPD was estimated to be 20.2 and 24.8 kJ/mol, respectively. The polymerization was totally inhibited by the addition of triethylamine and pyridine, but not hydroquinone. The polymerization rate in nitrobenzene was larger than that in toluene. These results indicated the cationic nature of the polymerization. γ‐PGA treated with KOH did not show the initiating activity of the polymerization. Therefore, carboxyl groups on γ‐PGA powder surface play an important role in the initiation of the polymerization. It may be suggested that the polymerization is initiated by proton addition to monomer from carboxyl groups on γ‐PGA powder surface and the propagation proceeds with carboxylate anion on the surface as counter ion. © 1993 John Wiley & Sons, Inc.
Polymerization of monoisocyanates by the Pruitt–Baggett adduct
Authors: Yilmaz Osman , Usanmaz Ali , Alyürük Kemal 
Published: April 2003

Abstractn‐Butyl isocyanate (nBIC) was polymerized in bulk by the Pruitt–Baggett adduct (PBA) at −23, 0.0, and 25.0°C. Polymerization was accompanied by trimerization to the cyclicisocyanurates at all temperatures. Spectroscopic evidences supported the nylon‐1 structure for both trimer and polymer. The polymer/trimer ratio and the molecular weight of produced polymers were found to increase with decreasing temperature. The Pruitt–Baggett catalyst (PBC), which is the reaction product of (PBA + H2O) system, also polymerized nBIC, but with a relatively slower rate. In aromatic and etheric solutions, nBIC was only trimerized by PBA. Copolymerization of nBIC with propylene oxide by PBA and PBC failed. Some selected monoisocyanates were also polymerized by PBA. © 1993 John Wiley & Sons, Inc.
Thermoplastic and thermoset main chain liquid crystal polymers prepared from biphenyl mesogen
Authors: Su W‐F. A. 
Published: April 2003

AbstractMain chain liquid crystal thermoplastic polyesters and thermosetting epoxy resins were prepared using biphenyl mesogens. The melting points of the polyesters were effectively decreased by incorporating flexible methylene spacers into the polymer main chain. The liquid crystal epoxy resins exhibit high glass transition temperature, low thermal expansion coefficients, high dielectric strengths, and low dielectric loss. They are suitable for the preparation of self‐reinforcing molecular composites. © 1993 John Wiley & Sons, Inc.
Physicochemical and catalytic investigations of grafted poly(tetrafluoroethylene) complexed with some transition metal nitrates
Authors: El‐Sawy Naeem M. , Fagal Gehan A. , El‐Shobaky Gamil A. 
Published: April 2003

AbstractRadiation‐induced graft polymerization of methacrylic acid into poly(tetrafluoroethylene) by the mutual irradiation technique has been studied. The obtained hydrophilic solids were treated with solutions containing calculated amounts of iron, cobalt, nickel, or copper nitrates. The amounts of these transition metal nitrates were fixed at 16 wt%, expressed as metal oxide. IR, XRD, TG, and catalysis of CO oxidation reaction by O2 have been carried out on the various prepared solids. The results obtained revealed that most of iron and copper species were contributed in complex formation of the polymeric material via carboxylic groups while some of the cobalt and nickel were involved in the complex formation and the rest remained as separate phases. The thermal treatment either in air at 400°C or in vacuo at 240°C led to degradation of the treated grafted polymeric material with subsequent formation of poly(methacrylic acid) together with Co3O4 (poorly crystalline phase) and NiO (having moderate crystallinity) and minute amounts of Fe2O3 and CuO (undetected by XRD). The PTFE‐g‐PMAAc treated with the different transition metal nitrates and subjected to heating under vacuum at 240°C exhibited different catalytic activities that vary in the order: Co > Ni > Cu ≫ Fe. The catalytic activity was mainly dependent on the produced amount of free oxide and their degree of division. © 1993 John Wiley & Sons, Inc.
Optically clear simulataneous interpenetrating polymer networks based on poly(ethylene glycol) diacrylate and epoxy. II. Kinetic study
Authors: Lin Mu‐Shih , Jeng Kuen‐Tay , Huang Kun‐Yui , Shih Yen‐Fong 
Published: April 2003

AbstractSimultaneous interpenetrating polymer networks (SINs) based on diglycidyl ether of bis‐phenol A (DGEBA) and poly(ethylene glycol) diacrylate (PEGDA) in weight ratios of 100/0, 50/50, and 0/100 were blended and cured simultaneously by using benzoyl peroxide (BPO) and m‐xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 45, 55, 63, and 70°C. Concentration changes for both the epoxide and CC bond were monitored with FTIR. A rate expression for DGEBA cure kinetics was established with a model reaction of phenyl glycidyl ether (PGE) and benzylamine. Experimental results revealed that lower rate constants and higher activation energy for the SIN were found, compared with those for the constituent DGEBA and PEGDA network formation. A model of network interlock was proposed to account for this phenomenon. During simultaneous cure of DGEBA and PEGDA, the interlock (mutual entanglement) between DGEBA and PEGDA networks provided a sterically hindered environment, which subsequently increased the activation energy and reduced cure rates for both DGEBA and PEGDA. © 1993 John Wiley & Sons, Inc.
Regiodefined substituted poly(2,5‐thienylene)s
Authors: Gallazzi M. C. , Castellani L. , Marin R. A. , Zerbi G. 
Published: April 2003

AbstractThe polymerization of 3,3″‐dialkylterthiophenes overcomes the lack of regiospecificity associated (to some extent) with all the polymerization methods in use, thus allowing the preparation of perfectly regioregular polymers endowed with enhanced electrical and optical properties. Moreover, the larger spacing of the alkyl chains achieved with the insertion of an unsubstituted thiophene unit confers to such regioregular polymers an extraordinary doping stability. Two regiochemically defined alkoxy‐substituted terthiophenes were also polymerized and the effects of the effects of the presence and position of the alkoxy group on the polymerization reaction and on the polymer properties are discussed. © 1993 John Wiley & Sons, Inc.
Tetrahydrofuran and 3,3‐bis(chloromethyl) oxetane triblock copolymers synthesized by two‐end living cationic polymerization
Authors: Hsiue Ging‐Ho , Liu Ying‐Ling , Chiu Yie‐Shun 
Published: April 2003

AbstractTriblock copolymers based on tetrahydrofuran (THF) and 3,3‐bis(chloromethyl) oxetane (BCMO), BCMO‐block‐THF‐block‐BCMO and poly(BCMO‐co‐THF)‐THF‐(BCMO‐co‐THF), have been synthesized by two‐end living cationic polymerization with a bifunctional initiator, trifluoromethanesulfonic anhydride [(CF3SO2)2O]. The polymers are obtained by using the two end propagating species of poly(THF) to initiate the sequential BCMO polymerization. The resulting polymers are characterized by infrared (IR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC), confirming that the polymers are ABA‐type block copolymers. The identities of the molecular weights predetermined and which determined by GPC show the success of predetermining molecular weights of the polymers and preparing well‐defined polymers. The narrow polydispersities, 1.1–1.3, indicate that the chains are propagating by a living mechanism. © 1993 John Wiley & Sons, Inc.
Melt polymerization of hexachlorocyclotriphosphazene in the presence of organotin (IV) compounds
Authors: Cho Yangha , Sohn Youn Soo , Jun Moo‐Jin 
Published: April 2003

AbstractThe melt polymerization of hexachlorocyclotriphosphazene to poly(dichlorophosphazene) has been studied in the presence of organotin (IV) compounds. Unlike other typical Lewis acids, diethyltin (IV) chloride, Et2SnCl2, has shown to be an inhibitor for the thermal polymerization of the trimer, raising the activation energy to 70 kcal/mol. Diethyltin(IV) chloride remarkably delayed the rate of polymerization and efficiently inhibited the crosslinking reaction, thus leading to an improvement in the yield of the linear polymer without sacrifice to its molecular weight. © 1993 John Wiley & Sons, Inc.
Synthesis and copolymerization behavior of methacrylate dimers
Authors: Abbey K. J. , Trumbo D. L. , Carlson G. M. , Masola M. J. , Zander R. A. 
Published: April 2003

AbstractMethacrylic ester‐based dimers and oligomers were synthesized using a metal‐based catalytic chain transfer agent. Conditions were employed which maximized the yield of unsaturated dimers, and the copolymerization behavior of these dimers was investigated. The molecular weight and polymer yield were found to decrease with increasing dimer concentration in the copolymerization feeds. © 1993 John Wiley & Sons, Inc.