bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of aromatic poly(thioether ketone)
Authors: Ueda Mitsuru , Abe Tetsuya , Oda Mitsuo 
Published: April 2003

AbstractAromatic poly(thioether ketone)s were prepared by the direct polycondensation of aromatic dicarboxylic acids with aryl compounds containing ether or sulfide structures using phosphorus pentoxide/methanesulfonic acid (PPMA) as a condensing agent and solvent. Polycondensation proceeded smoothly and produced aromatic poly(thioether ketone)s with inherent viscosities up to 0.73 dL/g. The synthesis of substituted aryl ketones by the reaction of substituted benzoic acids with aryl compounds in PMMA was studied in detail to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(thioether ketone)s showed a 10% weight loss in air and nitrogen at around 450 and 460°C, respectively. © 1992 John Wiley & Sons, Inc.
Chlorothioxanthone‐Onium salts: Efficient photoinitiators of cationic polymerization
Authors: Manivannan G. , Fouassier J. P. , Crivello J. V. 
Published: April 2003

AbstractThe interaction of iodonium, sulphonium, phosphonium, arsonium, selenonium, and heterocyclic nitrogen salts with the excited triplet state of 2‐chlorothioxanthone (CTX) has been studied through time‐resolved laser spectroscopy. Bimolecular quenching rate constants (ke) have been measured for the first time. Measuring of the rate constants (kq) of the quenching reaction by monomers permits the calculation of charge transfer (øCT) quantum yields. © 1992 John Wiley & Sons, Inc.
Plasma polymerization of cyano compounds
Authors: Inagaki N. , Tasaka S. , Yamada Y. 
Published: April 2003

AbstractPlasma polymerizations of three cyano compounds—acrylonitrile (AN), 1,2‐dicyanoethylene (FN), and tetracyanoethylene (TCE)—were investigated by FT IR and XPS, and the transforamtion of cyano groups during the plasma polymerization was discussed. The results pointed out an aspect of the preparation of plasma films with cyano groups. Plasma polymerizations of AN, FN, and TCE deposited brown or dark brown films that contained carbon, nitrogen, and oxygen. The elemental composition of the plasma films, especially N/C atomic ratio, showed a monomer dependence but no rf power dependence. The plasma films contained amide and amino groups, and ketene‐imine and conjugated — C = N — structures as well as cyano groups as nitrogen functionalities, and carbonyl and carboxyl groups as oxygen functionalities. For the preparation of plasma films with cyano groups, compounds with more than two cyano groups themselves are not suitable as monomers. The operation of plasma polymerization under mild plasma conditions at low rf power and in no oxygen atmosphere is favorable for the preparation of plasma films with cyano groups. © 1992 John Wiley & Sons, Inc.
Kinetics and mechanism of emulsifier‐free emulsion polymerization. III. Particle growth mechanism of seeded styrene/potassium persulfate system
Authors: Chen Show‐An , Chang Herng‐Show 
Published: April 2003

AbstractFor seeded emulsifier‐free emulsion polymerizations of styrene/potassium persulfate (KPS)/water system using the three sizes of seeds: 1020, 1620, and 1923 Å, analysis on the data of conversion and MWD suggests a shell region polymerization mechanism for the particle growth period as the particle diameter is larger than about 1500–2000 Å. The shell region has thickness of about 100 Å. The occurrence of shell region polymerization is attributed to the higher average number of radicals per particle (n ≑ 2−7) for the large particle, causing the polymer radicals (with the sulfate ends anchoring on the particle surface) to be terminated by combination at lower MW. Thus, the radical ends have no chance to arrive at the core of the particles. As the smallest seed is used, the rate of polymerization is of zero order, the same as in the conventional emulsion polymerization. MW of the polymer produced in the cases, in which the shell region polymerization occurs, increases with conversion in the entire process, different from the conventional case in which the MW increases first up to about 60% conversion and then decreases. © 1992 John Wiley & Sons, Inc.
Model reactions of amine curing of glycidylamine epoxy resins: Homopolymerization of N‐methylglycidylaniline
Authors: Matĕjka Libor , Podzimek S˘tĕpán , Simonsick William J. , S̆pac̆ek Pavel , Dus̆ek Karel 
Published: April 2003

AbstractThe kinetics of homopolymerization of the monofunctional epoxide N‐methylglycidylaniline in the presence of a tertiary amine or an amino alcohol has been followed by reversed phase high performance liquid chromatography and size exclusion chromatography. The reaction products were identified by mass spectrometry using potassium ionization of desorbed species (K+IDS). 1,3‐Di‐N‐methylanilino‐2‐propanol (P) was the main reaction product and low molecular weight oligomers with Mn > 600 were also formed. The molecular weight and fraction of oligomers decrease with increasing concentration of the initiator. The suggested complex reaction mechanism involves formation of four stable oligomeric series initiated by reaction of the epoxide with either an OH group of (a) the amino alcohol, (b) product P, (c) traces of water, or (d) the tertiary amine to form ionic species resulting in the ionic propagation. Regeneration of the initiator and formation of new initiating centers during the polymerization are the causes of low molecular weights of oligomers. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of thermally reversible macroporous poly(N‐isopropylacrylamide) hydrogels
Authors: Wu Xue Shen , Hoffman Allan S. , Yager Paul 
Published: April 2003

AbstractMacroporous hydrogels are characterized by large pore sizes, high pore volumes, and high specific surface area. Besides these characteristics, macroporous hydrogels based on thermally reversible polymers respond to temperature changes much faster than hydrogels prepared by a conventional method. Crosslinked poly(N‐isopropylacrylamide) (polyNIPAAm) forms a thermally reversible hydrogel which shows a lower critical solution temperature (LCST) ca. 33°C in aqueous solutions. We have synthesized thermally reversible polyNIPAAm hydrogels having macroporous structures by a new method. These macroporous hydrogels have large pore volumes, large average pore sizes, and faster macromolecule permeation rates in comparison to conventional polyNIPAAm hydrogels synthesized by a conventional method. Compared with conventional polyNIPAAm hydrogels, the macroporous polyNIPAAm hydrogels have higher swelling ratios at temperatures below the LCST and exhibit faster deswelling and reswelling rates. The deswelling rates are especially rapid. These thermally reversible macroporous hydrogels may be very useful in controlled active agent delivery and toxin removal, as well as dewatering of solutions. Peptides or proteins may behave as if they were in bulk solution within the large aqueous pores, and this may reduce their inactivation when such gels are used for their storage and later release. The gels may also be useful in microrobotic devices due to their fast response to temperature. © 1992 John Wiley & Sons, Inc.
Characterization of the changes in the initial morphology for MgCl2‐supported Ziegler‐Natta polymerization catalysts
Authors: Ferrero M. A. , Koffi E. , Sommer R. , Conner W. C. 
Published: April 2003

AbstractRecently considerable detail has become available on the initial morphology and the morphological changes that occur for silica based Cr catalysts for ethylene polymerization. These catalysts are produced as a dry powder and may be employed either in gas phase or in slurry processes. MgCl2‐supported Ziegler‐Natta polymerization catalysts are often prepared and employed as slurries. They usually are never dried and thus few studies have employed the spectra of physical techniques common to the characterization of pore structure. In the current study, we have carefully removed the solvent for both ball‐milled and precipitated MgCl2‐supported catalysts. These catalysts are characterized by physical sorption, mercury porosimetry, and electron microscopy both as prepared and during the initial stages of polymerization (to ∼ 100 g of polymer/g of catalyst). We find that the initial catalyst may be represented by a complex agglomerate of small crystallites as contrasted with the branched pore network found in Cr/silica catalysts. As a result, it is concluded that the initial fragmentation of the MgCl2 based systems is more uniform as contrasted with the progressive fragmentation of the silica‐based system. This fragmentation mechanism facilitates the retention of greater polymer/catalyst surface during the initial stages of the polymerization. © 1992 John Wiley & Sons, Inc.
Preparation of copolymer microspheres of diethylene glycol dimethacrylate
Authors: Naka Yukihiko , Yamamoto Yukio 
Published: April 2003

AbstractPreparation of copolymer microspheres of diethylene glycol dimethacrylate (2G) with several comonomers by radiation‐induced radical polymerization is described. Ethyl methacrylate (EMA), acrylamide, maleic anhydride, and styrene gave microspheres successively. The copolymerization resulted in gelation more easily than the 2G homopolymerization. The allowed ratio of copolymerization is up to about 0.4 as the mole fraction of comonomer for the solution containing 10 vol % 2G monomer. Copolymerization affected the size of microspheres by keeping its narrow distribution. The size of microspheres was increased by the copolymerization with EMA and styrene and, was decreased with acrylamide. The formation of microsphere strongly depends on the crosslinking ability of monomers. The crosslinking ability and reactivity in the copolymerization cause the change of the size of the microspheres. © 1992 John Wiley & Sons, Inc.
Free‐radical copolymerization of styrene with N‐phenyl maleimide initiated by thiol
Authors: Cheng Haitao , Zhao Guoqiang , Yan Deyue 
Published: April 2003

Abstract2‐Methyl–2‐undecanethiol was found efficient to initiate the free‐radical copolymerization of styrene (St) with N‐phenyl maleimide (NPMI) at 40°C. The initial copolymerization rate increases with the increasing of thiol concentration at first, then keeps constant with the further increasing of the thiol concentration. The charge‐transfer complex (CTC) formed between St and NPMI was investigated in different solvents by using 1H‐NMR. There is no definite correlation between CTC equilibrium constant, K, and the polarity of the solvent. With the increasing of CTC concentration, both the copolymerization rate and NPMI content in copolymer enhances, indicating the participation of CTC in both initiation and propagation. The monomer reactivity ratios were calculated to be rNPMI = 0.052 and rSt − 0.166, showing an alternating tendency for the copolymerization of St with NPMI. The molecular weight approach has shown again the effect of CTC. The function of thiol as a regulator is mitigated due to the involvement of CTC. © 1992 John Wiley & Sons, Inc.
Para‐Xylylenes and analogues by base‐induced elimination from 1,4‐bis‐(dialkylsulfoniomethyl)arene salts in poly(1,4‐arylene vinylene) synthesis by the wessling soluble precursor method
Authors: Denton Frank R. , Sarker Ananda , Lahti Paul M. , Garay Raul O. , Karasz Frank E. 
Published: April 2003

Abstractpara‐Xylylenes are generated by treatment of various 1,4‐bis(dialkylsulfoniomethyl)arene dihalides with base in water, methanol, and aqueous acetonitrile, as shown by UV‐Vis spectroscopy. This procedure allows the monitoring of the transient xylylene monomers that yield polyelectrolyte precursor polymers for poly(arylene vinylene)s, formed by variations of the chemistry developed originally by Wessling and co‐workers. Alkoxy, alkyl, and halogen ring substituents on the sulfonium salt precursors do not greatly affect the ability to generate and observe the growth and decay of steady‐state concentrations of the para‐xylylene intermediates. Use of strong resonance‐acceptor substituents—such as cyano or nitro—on the ring reduces production of a strong para‐xylylene absorption, possibly due to reluctance of the ylides initially formed from the bis‐sulfonium salts to eliminate to the xylylenes. By variation of UV‐Vis conditions, it was found that use of 20% aqueous acetonitrile rather than water allowed formation of low to modest molecular weight polyelectrolytes in cyano‐substituted cases (Mw = 8000–37,000). Use of UV‐Vis test experiments should be useful for screening of bis sulfonium salt precursors that may be expected to give high molecular weight polyelectrolytes—in cases where para‐xylylene formation is easy—as well as for finding reaction conditions that will optimize polymer formation. © 1992 John Wiley & Sons, Inc.
Synthesis of AB(BA), ABA and BAB block copolymers of tert‐butyl methacrylate (A) and ethylene oxide (B)
Authors: Wang Jinshan , Varshney Sunil Kumar , Jerome Robert , Teyssie Philippe 
Published: April 2003

AbstractWell‐defined AB(BA), ABA, and BAB block copolymers of tert‐butyl methacrylate (tBMA) (A) and ethylene oxide (EO) (B) have been prepared by sequential living anionic polymerization of the two comonomers, irrespective of their addition order. Diphenyl methyl potassium and naphthalene potassium have been successfully used as mono‐ and difunctional initiators, respectively. In all cases, molecular weight and composition of the block copolymers can be predicted on the basis of the monomer over initiator molar ratio, and the molecular weight distribution is relatively narrow. Size exclusion chromatography, selective extractions of homopolymers, and 1H‐ and 13C‐NMR spectroscopy support that block copolymerization proceeds without homopolymer formation nor side reactions, e.g., transesterification reactions. The PtBMA blocks have been quantitatively hydrolyzed into polyacid ones with formation of polyacid‐b‐polyether block copolymers as supported by titration, 1H‐NMR, and IR analysis. © 1992 John Wiley & Sons, Inc.
Novel cyano‐containing copolymers of vinyl esters for piezoelectric materials
Authors: Hall H. K. , Padias Anne Buyle , Chu Guobei , Lee Hee‐Yeon , Kalnin Ilmar , Sansone Michael , Breckenridge George 
Published: April 2003

AbstractThe synthesis of a series of novel cyano‐containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α‐cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α‐cyanoacrylate with the vinyl esters have Tg's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para‐substituted styrenes to yield copolymers with high inherent viscosities and high Tg (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β‐dicyanoacrylate, methyl α‐cyanoacrylate, or MVCN were in the same range as the well‐studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher Tg's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.
Carbonation of polymeric organolithium compounds: Effects of chain end structure
Authors: Quirk Roderic P. , Yin Jian 
Published: April 2003

AbstractThe carbonation of the adduct of poly(styryl)lithium with 1,1‐diphenylethylene with gaseous carbon dioxide in benzene proceeds in high yield (>99%) compared to the inefficient functionalizations for poly(styryl)lithium (66%), poly(isoprenyl)lithium (59%), and polybutadienyl)lithium (27%). The quantitative carboxylation of poly(isoprenyl)lithium and poly(butadienyl)lithium requires the presence of larger amounts of Lewis bases such as THF ([THF]/[Li] = 300) or TMEDA ([TMEDA]/[Li] = 46) compared to poly(styryl)lithium in which a ratio of [TMEDA]/[Li] = 12 is effective. © 1992 John Wiley & Sons, Inc.
Thermal degradation of polymethacrylic acid
Authors: Ho Bang‐Chein , Lee Yu‐Der , Chin Wei‐Kuo 
Published: April 2003

AbstractThe thermal degradation of polymethacrylic acid was found to have two separate decomposition regions. The first decomposition region, due to anhydride formation primarily, was caused by the conversion of polymethacrylic acid to polymethacrylic anhydride. This reaction followed first‐order kinetics and had an activation energy of 40.5 kcal/mol. The second decomposition region was the thermal degradation for the corresponding polymethacrylic anhydride. In this region, the fragmentation of anhydride rings structure in polymethacrylic anhydride constitutes the major decomposition reaction with an activation energy of 37.4 kcal/mol. © 1992 John Wiley & Sons, Inc.
Synthesis of thermally‐induced phase separating polymer with well‐defined polymer structure by living cationic polymerization. I. Synthesis of poly(vinyl ether)s with oxyethylene units in the pendant and its phase separation behavior in aqueous solution
Authors: Aoshima Sadahito , Oda Hiroshi , Kobayashi Eiichi 
Published: April 2003

AbstractLiving cationic polymerization of alkoxyethyl vinyl ether [CH2CHOCH2CH2OR; R: CH3 (MOVE), C2H5 (EOVE)] and related vinyl ethers with oxyethylene units in the pendant was achieved by 1‐(isobutoxy)ethyl acetate (1)/Et1.5AlCl1.5 initiating system in the presence of an added base (ethyl acetate or THF) in toluene at 0°C. The polymers had a very narrow molecular weight distribution (M̄w/M̄n = 1.1–1.2) and the M̄n proportionally increased with the progress of the polymerization reaction. On the other hand, the polymerization by 1/EtAlCl2 initiating system in the presence of ethyl acetate, which produces living polymer of isobutyl vinyl ether, yielded the nonliving polymer. When an aqueous solution of the polymers thus obtained was heated, the phase separation phenomenon was clearly observed in each polymer at a definite critical temperature (Tps). For example, Tps was 70°C for poly(MOVE), and 20°C for poly(EOVE) (1 wt % aqueous solution, M̄n ∼ 2 × 104). The phase separation for each case was quite sensitive (ΔTps = 0.3–0.5°C) and reversible on heating and cooling. The Tps or ΔTps was clearly dependent not only on the structure of polymer side chains (oxyethylene chain length and ω‐alkyl group), but also on the molecular weight (M̄n = 5 × 103‐7 × 104) and its distribution. © 1992 John Wiley & Sons, Inc.
Substrate temperature effects on film chemistry in plasma depositions of organics. II. Polymerizable precursors
Authors: López Gabriel P. , Ratner Buddy D. 
Published: April 2003

AbstractThe influence of substrate temperature during plasma deposition on the chemistry of the organic films formed was examined. Plasma ionization of precursor gases that are polymerizable by conventional mechanisms was studied. Film chemistry was analyzed by x‐ray photoelectron spectroscopy (XPS). Monomers that polymerize by a free radical mechanism [2‐hydroxyethyl methacrylate (HEMA) and hexafluorobutadiene (HFB)] form more regular polymers (i.e. with less molecular rearrangement) by plasma deposition at low substrate temperatures than monomers that polymerize by ionic mechanisms [ethylene oxide (EO) and tetrahydrofuran (THF)]. In all cases, lowering the substrate temperature during deposition produces films with elemental composition virtually identical to that of the precursor gas. Comparison of high‐resolution XPS spectra of the deposited films with those for model polymers suggests that functional groups in the monomers used to generate the plasma are incorporated to a greater extent at low substrate temperatures. The effect of plasma power on the degree of precursor structure retention obtained when reduced substrate temperatures are employed was also examined. Plasma deposition of HEMA at low substrate temperatures and low plasma power produces thin films which are, by core level XPS, indistinguishable from HEMA polymerized by conventional methods. EO and THF films coated at low substrate temperatures on glass, polyethylene, or polytetrafluoroethylene varied widely in surface chemistry due to differences in film uniformity. Film quality (uniformity) is enhanced for these low reactivity precursors by pretreating substrates with an argon plasma. © 1992 John Wiley & Sons, Inc.
Preparation and characteristics of photocrosslinkable hydrophilic polymer having cinnamate moiety
Authors: Nakayama Yasuhide , Matsuda Takehisa 
Published: April 2003

AbstractThe reaction of copolymer of N,N‐dimethylacrylamide (DMAA) and bromoethyl methacrylate with potassium cinnamate produced water‐soluble photosensitive polymers. Photosensitive polyDMAA films were irradiated with a 400 W high‐pressure mercury lamp (λ > 280 nm) to produce crosslinked polymers, which were swollen in water. The degree of swelling was controlled by the irradiation time and content of cinnamate moieties in copolymers. Higher cinnamoylation and longer irradiation time resulted in higher yield of crosslinked polymers and less swellability. Partial degelation upon irradiation at λ ∼ 254 nm was observed. The advantage of gelation via photodimerization over conventional chemical crosslinking methods is discussed in conjunction with biomedical applications. © 1992 John Wiley & Sons, Inc.
Synthesis of aromatic polymers via palladium‐catalyzed cross‐coupling reactions with magnesium, zinc, and tin reagents: A comparison
Authors: Bochmann M. , Kelly K. , Lu J. 
Published: April 2003

AbstractDifunctional magnesium, zinc, and tin reagents MC6H4OC6H4M (M = MgBr, ZnCl, SnBu3) in the presence of palladium or nickel catalysts undergo cross‐coupling polymerizations with aromatic, heteroaromatic, benzylic, and allylic dihalides to give oligomeric and polymeric materials. Tin reagents lead to products of higher molecular weight than Mg and Zn reagents. The reaction is sensitive to the solvent and enhanced by magnesium halides. Increased reaction temperatures lead only to moderate increases in the degree of polymerization and are limited by catalyst decomposition above 200°C. The new poly(ether ketone) and poly(ether sulfone) type polymers prepared show high thermal stability. In contrast to conventional poly(ether sulfones)s, the biphenyl‐based sulfone polymers reported here are crystalline. © 1992 John Wiley & Sons, Inc.
Determination of microstructure and glass‐transition temperature of acrylonitrile‐methyl acrylate copolymers by 13C‐NMR spectroscopy
Authors: Brar A. S. , Sunita  
Published: April 2003

AbstractAcrylonitrile‐methyl acrylate (A/M) copolymers of different monomer compositions were prepared by bulk polymerization using free radical initiator (benzoyl peroxide). Copolymer compositions were determined by elemental analyses and comonomer reactivity ratios were determined by the nonlinear least squares errors‐in‐variables methods (EVM). Terminal and penultimate reactivity ratios have been calculated using the observed monomer triad sequence distribution determined from 13C{1H}‐NMR spectra. The triad sequence distribution was used to calculate diad concentrations, conditional probability parameters, number‐average sequence lengths, and run number in the copolymers. The observed triad sequence concentrations determined from 13C{1H}‐NMR spectrum agreed well with those calculated from reactivity ratios. Glass transition temperatures (Tg) of various copolymers determined from DSC gave good agreement with those obtained from NMR. © 1992 John Wiley & Sons, Inc.