摘要:

AbstractThe macromolecular bound protoporphyrin IX and its metal complexes, poly‐(protoporphyrin‐co‐acrylamide), cobalt(II) [poly(protoporphyrin‐co‐acrylamide)], zinc‐(II)[poly(protoporphyrin‐co‐acrylamide)], and manganese(III) [poly(protoporphyrin‐co‐acrylamide)] chloride were synthesized. The absorption and emission spectra have been obtained for the macromolecular porphyrins. The lifetime of the excited singlet state of the protoporphyrin IX was found to decrease from 13.7 to 6.2 ns after polymerization. The cyclic voltammograms of polymeric protoporphyrin coated electrodes have been obtained. © 1992

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301201

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractWe describe a new method for the polymerization of perchloroaromatic compounds using Fe(CO)5as a dechlorinating agent which allows the syntheses of perchloropoly‐1,4‐phenylene vinylene (8), perchloropoly‐4,4'‐biphenylene vinylene (9), and perchloropoly‐1,3‐phenylene vinylene (10) from perchloro‐p‐xylene (5), perchlorobi‐p‐tolyl (6), and perchloro‐m‐xylene (7), respectively. Polymer10, a new macromolecular chlorocarbon, was characterized by elemental analysis and infrared and ultraviolet spectra. The molecular weights (MW's) of the polymers were estimated by osmometry. The XPS spectra of these polymers are discussed. Their thermal properties were studied by thermogravimetry. Electron spin resonance (ESR) studies and some preliminary conductivity measurements, made after doping the polymers with SbF5, are reported. © 1

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301202

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSCFab initioand AM1 semiempirical calculations with full geometry optimization have been carried out to model the initial steps of alkenylfuran cationic polymerization. Semiempirical procedures have been used to model propagation steps. Proton affinities of the relevant neutral species as well as the heats of formation of probable dimers were calculated. The results allow the explanation of the experimental behavior. The capabilities of the employed methods to describe these type of processes is discussed. It is confirmed that competition between vinyl and ring site attacks is the most important feature in these systems. © 1992 John Wiley&Sons, Inc

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301203

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractComparative studies have been carried out of the effectiveness of two organometallic coupling reagents for the synthesis of poly(alkynylarene)s via palladium catalyzed cross‐coupling reactions of dialkynes with organic dibromides. In comparison to copper reagents, monomeric difunctional trialkyltin acetylides show increased thermal stability which allows reactions to be performed at higher temperatures; they give oligomeric and polymeric materials of improved molecular weight. By contrast, the inferior solubility of copper acetylides limits chain growth, and above 140°C the Pd/Cul system is prone to homopolymerization of the dialkyne. The coupling reactions are solvent‐dependent but not strongly influenced by the nature of the palladium precursor complex or the phosphine ligand. © 1992 John Wiley&Sons

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301204

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

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 Wi

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301205

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe influence of certain phosphorus substituted (OH, OMe, Me) 3,3'‐diphenylphosphine oxides on flammability and thermal stability of 1,3‐phenylene isophthalamide copolymers was investigated. Introduction of the above phosphorus groups along the backbone of poly(1,3‐phenylene isophthalamide) was performed in a random manner to a degree of ca. 5‐15 mol %. From the limiting oxygen index (LOI) measurements on copolymers, it was found that the diphenylphosphinic acid group has the highest flame retardance efficiency with an increase of LOI 44‐56%. From thermogravimetric analysis (TGA), it was found that the action of phosphorus groups is limited in the solid phase, increasing the char yield to 27‐42%. This was attributed to crosslinking reactions at the stage of amide bond decomposition. © 1992 John Wil

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301206

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractKinetic studies on the polymerization ofn‐butyl acrylate andn‐octadecyl acrylate in toluene at 70°C with benzoyl peroxide as initiator are reported. High monomer orders of 1.55 and 1.75 were obtained forn‐butyl andn‐octadecyl acrylates, respectively. Though the initiator order in butyl acrylate polymerization was 0.5, the octadecyl acrylate polymerization showed less than square root initiator order. The activation energy for the polymerization of both the acrylates was determined. Autoacceleration was found even at low conversions. The autoacceleration was influenced by both monomer and initiator concentration. Molecular weight data was presented in support of the gel effect. © 1992 John Wiley&

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301207

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractNew liquid‐crystalline (LC) polymers and small molecules have been synthesized based on the 1,4‐diphenylbutadiene mesogen, a chromophore with χ(3)nonlinear optical properties. Polyethers were formed by phase‐transfer reaction, and polyesters were prepared by Schotten‐Bauman polymerization from these 4,4'‐bisphenolic mesogenic structures. Liquid crystallinity was examined using differential scanning calorimetry (DSC) and optical microscopy. Most of the model compounds were found to be nematic. All mesomorphic polymers were nematic and displayed LC ranges of up to 50°C as well as a wide diversity of melting points. The melting points varied with the flexible (methylene) spacer length and were strongly dependent upon the presence of substituents in the mesogenic core. Crosslinking and cis‐trans isomerization were observed under the influence of heat and ultraviolet radiation. © 1992 John W

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301208

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

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 from13C{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 from13C{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 Wil

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301209

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractCertain AB or AA and BB Diels‐Alder polymer precursors bearing maleimide and furan segments were synthesized, characterized, and polymerized. Particularly, the monomaleamic acid derived from 4,4'‐diaminodiphenylmethane, reacted with the monofurfurylpyromellitamic acid to yield a triamic acid which was cyclodehydrated to the corresponding triimide. A polyimide was obtained upon heat‐curing of triimide or the intermediate triamic acid. In addition, equimolar amounts ofN,N'‐bismaleimido‐4,4'‐diphenylmethane (BMDM) and bisfurfurylpyromellitimide or their intermediate diamic acids were cured to afford a polyimide. The polymer precursors were characterized by IR and1H‐NMR spectroscopy and their curing behavior was investigated by DTA. It was shown that the Diels‐Alder polymerization of monomers took place at lower temperature than that required for crosslinking of BMDM. The thermal stabilities of polymers were ascertained by TGA and isothermal gravimetric analysis (IGA). The synthesized Diels‐Alder polymers were remarkably more heat‐resistant than the crosslinked polymer obtained from BMDM or its intermediate bismaleamic acid. They were stable up to about 360°C in N2or air and afforded anaerobic char yield of 58% at 800°C. © 199

ISSN:0887-624X    

DOI:10.1002/pola.1992.080301210

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY