IMIDE-ARYL ETHER PHENYLQUINOXALINES .2.

Novel imide-aryl ether phenylquinoxaline copolymers were prepared and their morphology and thermal properties investigated. A key feature of these copolymers is the incorporation of an aryl ether phenylquinoxal ine linkage into a semi-rigid polyimide backbone based in pyromellitic dianhydride (PMDA) with 4,4'-oxydianiline (ODA) and either 2,3-bis-[( 3-aminophenoxy)phenyl]quinoxaline or 2,3-bis[(4-aminophenoxy)phenyl]qu inoxaline as co-diamines. These monomers were prepared by a novel nucl eophilic aromatic substitution reaction of 2,3-bis(4-fluorophenyl)quin oxaline with 4- or 3-aminophenol in the presence of K2CO3 These diamin es were used as co-monomers with PMDA and ODA to synthesize poly(amic- acids) which were cast and cured (350 degrees C) to effect imidization , affording tough films. The copolymers with high phenylquinoxaline co mpositions displayed glass transition temperature values in the 300 de grees C range. The thermal stability of the copolymers was comparable to that of the parent polyimide, with decomposition temperatures betwe en 455 and 480 degrees C. The morphology of the copolymers was investi gated by dynamic mechanical thermal analysis and wide angle X-ray diff raction. (C) 1997 Elsevier Science Ltd.