Abstract
Novel imide-aryl ether benzothiazole copolymers were prepared and their morphology and mechanical properties investigated. Diamines containing preformed benzothiazole rings were prepared and used in conventional polyimide syntheses. The preparation of these diamines involved the nucleophilic aromatic substitution reaction of 2,6-bis(4-fluorophenyl)benzo[1,2,4,5]bisthiazole with either 3- or 4-aminophenol in the presence of K2CO3 in N-methyl-2-pyrrolidone to afford 2,6-bis(4-aminophenoxy-4-phenyl)benzo[1,2,4,5]dithiazole and 2,6-bis(3-aminophenoxy-4-phenyl)benzo[1,2,4,5]dithiazole, respectively. The monomers were each reacted with pyromellitic dianhydride to synthesize the desired poly(amic acids). Films were cast and cured to 350°C to effect imidization, producing films with good mechanical properties. The copolymers exhibited good dimensional (Tg > 400°C) and thermal stability. Wide angle X-ray diffraction measurements showed that in one case a semicrystalline morphology was obtained producing a film with both a high modulus and low thermal expansion coefficient. © 1992.