Comparative studies of newly synthesized azo-dyes bearing poly(esterimide)s with their poly(etherimide) analogues. Light-induced optical anisotropy

Two types of novel poly(esterimide)s with rigidly and flexibly attached azobenzene chromophores to the main chain were synthesized and characterized. Poly(esterimide)s with rigidly bounded chromophore were synthesized from 4,4′[diphenylopropane-di(benzene-4-estro-1,2-dicarboxylic)]anhydride and 2,4-diamino-4′-cyanoazobenzene and 2,4-diamino-4′-methylazobenzene. Poly(esterimide)s with flexible i.e. by aliphatic spacer (-O-(CH2)6-O-) bonded azo-dye were prepared from hydroxyl poly(esterimide) by the covalent bonding of 4-[4-(6-hydroxyhexyloxy)phenylazo]benzonitrile and 4-[4-(6-hydroxyhexyloxy)phenylazo]toluene via Mitsunobu reaction. The degree of functionalization of the poly(esterimide)s was estimated by UV-Vis spectroscopy. Glass transition temperature (Tg) of the polymers and decomposition temperature (Td) at 5% weight loss were in the range 167-264 °C and 368−442 °C, respectively. Light-induced anisotropy in poly(esterimide)s and in their analogues poly(etherimide)s was studied by holographic grating recording performed at wavelengths λ1 = 476 and λ2 = 514.5 nm using two crossed coherent laser beams. The surface relief gratings which appeared after light exposure were observed by atomic force microscopy.