Reversible addition-fragmentation transfer polymerization of p-nitrophenyl acrylate and synthesis of diblock copolymers poly(p-nitrophenyl acrylate)-b-polystyrene

Poly(p-nitrophenyl acrylate)s (PNPAs) with different molecular mass and narrow polydispersity were successfully synthesized for the first time by reversible addition-fragmentation transfer (RAFT) polymerization with azobisisobutyronitrile (AIBN) as an initiator and [1-(ethoxy carbonyl) prop-1-yl dithiobenzoate] as the chain-transfer agent. Although the molecular mass of PNPAs can be controlled by the molar ratio of NPA to RAFT agent and the conversion, a trace of homo-PNPA was found, especially at the early stage of polymerization. The dithiobenzoyl-terminated PNPA obtained was used as a macro chain-transfer agent in the successive RAFT block copolymerization of styrene (St) with AIBN as the initiator. After purification by two washings with cyclohexane and nitromethane to remove homo-PSt and homo-PNPA, the pure diblock copolymers, PNPA-b-PSt's, with narrow molecular weight distribution were obtained. The structural analysis of polymerization products by H-1 NMR and GPC verified the formation of diblock copolymers. (C) 2004 Wiley Periodicals, Inc.