Synthesis and characterization of high performance polymers from enaminonitrile group containing monomers

Abstract

The new diamine monomer containing one enaminonitrile unit, [(p-aminophenylamino)-4-aminophenylmethylidene]propanedinitrile, was synthesized, and polymerized with aromatic acid chlorides and aromatic diamines to poly(amide-co-enaminonitriles). The synthesized poly(amide-co-enaminonitriles), PAEs, which do not have any flexible linkage are analogous to aramids such as Kevlar and Nomex. The PAEs showed excellent thermal stability as well as improved solubility compared to Kevlar. They were soluble in polar aprotic solvents such as N-methylpyrrolidone and dimethyl sulfoxide. The 5% weight loss temperature of the PAEs occurred between 435 and 510℃ in nitrogen, and between 430 and 510℃ in air. All the synthesized PAEs exhibited broad irreversible exothermic transitions between 300 and 350℃, which indicate curing of enaminonitrile groups without emission of volatile by products. The polymers became insoluble after curing. In order to study the curing reaction of poly(enaminonitriles), the model compounds containing quinoline moiety were synthesized through acid-catalyzed cyclization reaction of the compounds containing an enaminonitrile group.