Polymerization of N-[4-(azidocarbonyl)phenyl]maleimide and N-[4-(N '-phenoxycarbonylamino)phenyl]maleimide polymers containing aromatic isocyanate precursors

N-[4-(Azidocarbonyl)phenyl] maleimide (3) and N-[4-(N'-phenoxycarbonylamino )phenyl]maleimide (5) were polymerized and copolymerized with methyl methac rylate (MMA) or acrylic acid (AA) by initiation with AIBN. The resultant po lymers were to have aromatic isocyanato groups when heated. In the differen tial scanning calorimetry measurement, the polymers from monomer 3 showed a strong and broad exotherm around 130 degrees C. Thermogravimetric analysis also showed a weight decrease corresponding to the elimination of nitrogen at that temperature. The formation of isocyanato groups was confirmed by i nfra-red measurement with varying the cell temperature. The coupling reacti on of the polymer with N-4-(nitrophenyl)-L-prolinol, resulting in the forma tion of urethane bonds, was carried out in a quantitative yield. The crossl inked films from copolymers of 5 and MMA or AA were obtained when heated ab ove 200 degrees C. The cured films were insoluble in common organic solvent s. With the copolymers with AA it was expected that carboxylic groups would react with isocyanato groups generated from urethane units when heated. Th e copolymer was degraded above 150 degrees C. After curing, its thermal sta bility improved dramatically, no weight loss being observed up to 300 degre es C. (C) 1999 Elsevier Science Ltd. All rights reserved.