Polystyren-block-poly(vinyl acetate) through the use of a switchable RAFT agent

This paper reports the application of "switchable" RAFT agents to the synthesis of PS-block-poly(VAc) (a) directly, (b) as PS-block-poly(MA)-block-poly(VAc), and (c) as PS-block-poly(MA-grad-VAc)-block-poly(VAc). Process (a) is complicated by an inhibition period and the formation of some dead polymer, (b) is a three-step process but should generally yield a product of higher purity, and (c) is most convenient but, because of the slow rate of consumption of the macro-RAFT agent, is only suitable when a longer PVAc block is required.