Novel aromatic polyamides bearing pendent diphenylamino or carbazolyl groups

Two new diamines, 2,4-diaminotriphenylamine (3) and N-(2,4-diaminophenyl)carbazole (4), were synthesized via the cesium fluoride-mediated aromatic substitution reactions of 1-fluoro-2,4-dinitrobenzene with diphenylamine and carbazole, followed by palladium-catalyzed hydrazine reduction. Amorphous and soluble aramids having pendent diphenylamino and carbazolyl groups were prepared by the phosphorylation polycondensation of aromatic dicarboxylic acids with diamines 3 and 4, respectively. The aramids derived from diamine 3 had sufficiently high molecular weights to permit the casting of flexible and tough films. They exhibited excellent mechanical properties and moderately high softening temperatures in the 221-298 degreesC range. However, the reactions of diamine 4 with aromatic diacids gave relatively lower molecular weights products that could not afford flexible films. For a comparative purpose, the parent aramids derived from m-phenylenediamine and aromatic diacids were also prepared and characterized. (C) 2004 Wiley Periodicals, Inc.