One-pot synthesis of poly(vinyl alcohol)-based biocompatible block copolymers using a dual initiator for ROP and RAFT polymerization

Biocompatible poly(ε-caprolactone)-b-poly(vinyl alcohol) (PCL-b-PVA), poly(δ-valerolactone)-b-PVA, and poly(trimethylene carbonate)-b-PVA block copolymers were synthesized at 30 °C using a hydroxyl-functionalized xanthate reversible addition-fragmentation chain transfer (RAFT) agent, 2-hydroxyethyl 2-(ethoxycarbonothioylthio)propanoate, as a dual initiator for ring-opening polymerization (ROP) and RAFT polymerization in a one-pot procedure. The ROP of ε-caprolactone, δ-valerolactone, and trimethylene carbonate was first performed using diphenyl phosphate as the ROP catalyst followed by the RAFT polymerization of vinyl chloroacetate after quenching the ROP with 4-dimethyamino pyridine. The resulting block copolymers were aminolyzed directly to the PVA-based biocompatible block copolymers by adding hexylamine to the reaction mixture. To the best of our knowledge, this is the most convenient method for synthesizing PVA-based biocompatible block copolymers.