SYNTHESIS OF PHOTO-RESPONSIVE POLYAMIDES CONTAINING NORBORNADIENE RESIDUES IN THE MAIN-CHAIN USING DIISOCYANATES

Several new photo-responsive polyamides containing norbornadiene (NBD) residue in the main chain were synthesized by the polycondensation of 2,5-NBD-2,3-dicarboxylic acid (NDC) with diisocyanates. From a polycondensation without catalyst in sulfolane at 80 degrees C for 24 h, NBD polyamide having a number average molecular weight of (M(n))=11000 was obtained. In the reaction using various catalysts, however, it was found that the molecular weight of the resulting polymer did not increase. The reaction was investigated in various solvents without catalyst. The reaction proceeded very smoothly in dimethyl sulfoxide (DMSO) at room temperature to give the corresponding polymer with M(R)=8000. When the reaction was carried out in DMSO at 100 degrees C, the polymer having the highest molecular weight (M(n)=20000) was obtained. Various NBD polyamides were also prepared by the reaction of NDC with certain diisocyanates under similar conditions.