PHOTOGELATION AND REDOX PROPERTIES OF ANTHRACENE DISULFIDE-MODIFIED POLYOXAZOLINES

Polyoxazoline having both anthracene and disulfide groups was prepared by the reaction of partially hydrolyzed poly(N-acetylethylenimine) (P AEI) with (9-anthracenyl)methyl hydrogen 3,3'-dithio-dipropanoate in t he presence of dicyclohexylcarbodiimide (DCC) as a condensing agent. T his photosensitive PAEI was irradiated with a 450-W high-pressure Hg l amp (lambda > 300 nm) to produce a PAEI gel, which was swollen in wate r and showed characteristic hydrogel properties. The equilibrium swell ing degree in water was controlled both by the irradiation time and by the degree of substitution of the anthracene moieties. The water upta ke was up to 20 times the weight of the dry gel. The photo-cross-linke d PAEI gel became soluble by the reductive cleavage of disulfide cross -links. The gelation by photoreaction and the cleavage by reduction co nstitute a novel photosensitive and redox-sensitive hydrogel system.