Molecular design of block and graft copolymers by vinyl‐substituted xanthates

Abstract

Abstract The selective polymerization behavior of O ‐ethyl S ‐4‐vinylbenzyl xanthate (1) was investigated on the basis of polymerization kinetics in the dark and in the presence of UV‐light. S ‐Benzyl O ‐ethyl xanthate (2) was used as a non‐polymerizable model compound of 1 to evaluate chain transfer constants. In the homopolymerization and the copolymerization of 1 initiated with AIBN in the dark, styryl groups selectively take part in the polymerization, and xanthate groups are not responsible for it. The monomer reactivity ratios ( r 1 = 0,51 and r MMA = 0,41) of 1 with methyl methacrylate (MMA) are very close to those of styrene with MMA. The photolysis of 2 was investigated by 1 H NMR. It was found that photodecomposition of 2 takes place at CH 2 S (a) and SC( = S) bonds (b) with the ratio: a/b = 1/5. The polymerization of MMA was carried out with 1 upon photoirradiation. Number‐average degrees of polymerization of the polymers obtained increase linearly with conversion. Block and graft copolymers were prepared by using these macrophotoinitiators.