High-molecular-weight poly arylene

The SnAt reactions were first successfully used in the synthesis of high-molecular-weight poly(arylene etherjs by Johnson et al.4,5 This reaction represents a good example for poly(ether sulfonejs in general, either in laboratory -or industrial-scale preparations. In this procedure, the bisphenol A and sodium hydroxide with an exact mole ratio of 1 2 were dissolved into dimethyl sulfoxide (DMSO)-chlorobenzene. The bisphenol A was converted into disodium bisphenolate A, and water was removed by azeotropic distillation. After the formation of the anhydrous disodium bisphenolate A, an equal molar amount of 4,4,-dichlorodiphenyl sulfone (DCDPS) was added in chlorobenzene under anhydrous conditions and the temperature was increased to 160°C for over 1 h... 

L. Lutsen, P. Adriaensens, H. Becker, A.J. Van Breemen, D. Vanderzande, and J. Gelan, New synthesis of a soluble high molecular weight poly(arylene vinylene) poly[2-methoxy-5-(3,7-dimethyloctyloxy)-p-phenylene vinylene]. Polymerization and device properties, Macromolecules, 32 6517-6525, 1999. 

The transition metal-catalysed coupling of aryl halides with alkenes (alkenyla-tion of aromatic halides) is referred to as the Heck reaction [66-75]. Heitz et al. [76-82] were the first to utilise the Heck reaction to synthesise high molecular weight poly(arylene vinylene)s by the self-coupling of bromostyrene [scheme (2)] or the cross-coupling of dibromoarene with ethylene [scheme (4)] or divi-nylarene [scheme (5)]. 

C. E. Ash, J. F. Geibel, and H. D. Yelton. Process for preparing high molecular weight poly(arylene sulfide) polymers using lithium salts. US Patent 5 929 203, assigned to Phillips Petroleum Company (Bartlesville, OK), July 27, 1999. 

Allegations that poly(phenylene sulfide) was originally prepared by the reaction of benzene and sulfur with AlCl are a result of creative reading of the literature. Formation of high molecular weight poly(arylene sulfides) in the presence of AlCl is highly unlikely because the latter catalyzes both polymerization and degradation reactions. 

J. D. Capistran, D. R. Gagnon, S. Antoun, R. W. Lenz, and F. E. Karasz, Synthesis and electrical conductivity of high molecular weight poly(arylene vinylene), Polym. Prepr. 1984.2S2. 

Tn 1959 Hay (19) reported that 2,6-xylenol reacts with oxygen in the presence of a pyridine-cuprous chloride catalyst to yield a high molecular weight poly(l,4-arylene oxide) (Reaction 1). 

Poly(arylene vinylenes). The use of the soluble precursor route has been successful in the case of poly(arylene vinylenes), both those containing ben2enoid and heteroaromatic species as the aryl groups. The simplest member of this family is poly(p-phenylene vinylene) [26009-24-5] (PPV). High molecular weight PPV is prepared via a soluble precursor route (99—105). The method involves the synthesis of the bis-sulfonium salt from /)-dichloromethylbenzene, followed by a sodium hydroxide elimination polymerization reaction at 0°C to produce an aqueous solution of a polyelectrolyte precursor polymer (11). This polyelectrolyte is then processed into films, foams, and fibers, and converted to PPV thermally (eq. 8). 

The nucleophilic aromatic substitution reaction for the synthesis of poly(arylene ether ketone)s is similar to that of polysulfone, involving aromatic dihalides and aromatic diphenolates. Since carbonyl is a weaker electron-withdrawing group titan sulfonyl, in most cases, difluorides need to be used to afford high-molecular-weight polymers. Typically potassium carbonate is used as a base to avoid the... 

Robeson and Matzner were the first to report the synthesis of the sulfonation of DCDPS.205 This work makes it possible to synthesize sulfonated poly(arylene ether sulfone) with well-controlled structures. Ueda et al. used this monomer (Scheme 6.27) as a comonomer of DCDPS to react with bisphenol A and high-molecular-weight bisphenol-A-based copolymers with up to 30 mol % sulfonation achieved.206 Biphenol-based copolymers with up to 100 mol % sulfonation were recently reported by Wang et al.207... 

Further work on poly(arylene ether phenylimidazole)s led to a series of polymers containing two phenylimidazole units per mer unit (Eq. (5)) [24]. The dihydroxy monomers, 2,2 -(l,3- and l,4-phenylene)bis[(4-phenylhydroxy)-5-phenylimidazole] were prepared from the reaction of iso or terephthaldehyde, 4-hydroxybenzil and ammonium acetate in refluxing acetic acid. High molecular weight polymers as represented in Table 6 were readily prepared in DMAc. 

Many factors contribute to the toughness of a polyphase BMI/thermoplastic system, such as solubility parameters, phase adhesion, phase morphology, particle size and particle size distribution. Another important factor is the molecular weight of the thermoplastic modifier. It has been demonstrated for a particular poly(arylene-ether) backbone that high molecular weights increase the toughness of the blend system more than the low molecular weight counterparts (92). 

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