Synthesis and Properties of p-aromatic Polyamide Having Benzoxazinone Unit in the Main Chain

Abstract

Many heterocyclic polymers have been recently reported as thermally stable polymers. Polymer containing the benzoxazinone unit in the main chain known to have remarkable thennal stability is one of them. Polybenzoxazinones^1,2 are capable of being prepared by the reaction of suitable aromatic diaminodicarboxylic acids with aromatic dicarboxylic acid halides in polyphosphoric acid at high tempera tare or in dimethyl acetamide(DMAc) at low temperature. Our interest in polyamides having pendant ethoxycarbonyl groups has led to the synthesis of aromatic poly (4,4′-diamino-6-ethoxycarbonyl benzanilido terephthalamide) (PDEBTA) by solution polymerization of 4,4′-diamino-6-ethoxycarbonyl benzanilide with terephthaloyl chloride. The mechanism of cyclization of aromatic PDEBTA will be described on the basis of a model compound reaction and the physical properties of uncyclized PDEBTA are also to be discussed.