PREPARATION OF CHITIN POLYSTYRENE HYBRID MATERIALS BY EFFICIENT GRAFT-COPOLYMERIZATION BASED ON MERCAPTOCHITIN/

Graft copolymerization of styrene onto mercaptochitin has been examine d. Chitin was first tosylated to give tosylchitin, which was subsequen tly transformed into mercaptochitin. Although the graft copolymerizati on was carried out in suspension, it proceeded efficiently to give chi tin derivatives having polystyrene branches, a novel type of hybrid ma terials composed of a natural polysaccharide and a synthetic polymer. Under appropriate conditions, the grafting percentage reached 970%, in dicating the high efficiency of the mercaptochitin as an initiator for the polymerization of styrene. The resulting graft copolymers exhibit ed glass transition phenomena at 115 degrees C and showed high swellin g in organic solvents as a result of the introduction of polystyrene b ranches. Hydrolytic degradation of the chitin main chain allowed the i solation of the side chains, and the polystyrene isolated from the gra ft copolymer with a grafting percentage of 940% had M(n), M(w), and M( w)/M(n) values of 9.74 x 10(4), 2.55 x 10(5), and 2.62. These values i ndicate that the ratio of the mercapto groups actually used for initia ting graft copolymerization was 4%, and a polystyrene chain attached o n average to every 45 pyranose units.