SYNTHESIS AND CHARACTERIZATION OF POLYIMIDES AND POLYAMIDE-IMIDES CONTAINING AZOMETHINE LINKAGES

Polyimides and polyamide-imides containing azomethine linkages in the polymer backbone have been synthesized from 4,4'-bis(4-isocyanatobenzylidene)-diaminodiphenylether (ODAI), 4,4'-bis(4-isocyanatobenzylidene)-diaminodiphenylmethane (MADI), 4,4'-bis(4-isocyanatobenzylidene)-diaminodiphenylsulphone (SDAI), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and trimellitic anhydride (TMA). by a one-step process. The diisocyanates ODAI, MDAI and SDAI were prepared from the corresponding diacids, namely. 4,4'-bis(4-carboxybenzylidene)-diaminodiphenylether (ODAA), 4,4'-bis(4-carboxybenzylidene)-diaminodiphenylmethane (MDAA) and 4,4'-bis-(4-carboxybenzylidene)-diaminodiphenylsulphone (SDAA) by a Weinstock-modified Curtius rearrangement method. All the polycondensation reactions were conducted in N-methyl-2-pyrrolidone (NMP) under identical conditions and the polymers obtained were characterized by IR spectroscopy, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction.