CATIONIC AND RADICAL GRAFT-COPOLYMERIZATION OF STYRENE ONTO IODOCHITIN

Iodochitin was evaluated as a precursor for graft copolymerization of styrene both by a cationic and a free-radical mechanism. In the presence of Lewis acids, cationic species were formed at the carbons bearing an iodo group, and graft copolymerization of styrene proceeded efficiently in nitrobenzene or somewhat less efficiently in nitromethane. As a catalyst, SnCl4 was superior to TiCl4. Grafting percentages were as high as 800 % under appropriate conditions. The polystyrene branches were isolated by hydrolytic degradation of the chitin main chains and characterized by GPC. On irradiation of the iodochitin by an excimer laser, the C-I bonds of iodochitin were cleaved to free radicals which initiated styrene grafting. The grafting percentages were not high in the radical graft copolymerization, but very little homopolystyrene was formed. The resulting chitin-graft-polystyrenes were much more soluble or swollen in organic solvents.