Preparation of well-defined block copolymer having one polystyrene segment and another poly(styrene-alt-maleic anhydride) segment with RAFT polymerization

摘要

Block copolymers, polystyrene-b-poly(styrene-co-maleic anhydride), have been prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technique using three different approaches: 1-phenylethyl phenyldithioacetate (PEPDTA) directly as RAFT agent, mediated polystyrene (PS) block as the macromolecular PS-RAFT agent and mediated poly(styrenemaleic anhydride) (SMA) block with alternating sequence as the macromolecular SMA-RAFT agent. Copolymers synthesized in the one-step method using PEPDTA as RAFT agent possess one PS block and one SMA block with gradient structure. When the macromolecular RAFT agents are employed, copolymers with one PS block and one alternating SMA block can be produced. However, block copolymers with narrow molecular weight distribution (MWD) can only be obtained using the PS-RAFT agent. The MWD deviates considerably from the typical RAFT polymerization system when the SMA is used as the RAFT agent.