Synthesis and characterization of novel epoxy- and oxetane-functional reversible addition-fragmentation chain transfer agents

Novel reversible addition-fragmentation chain transfer (RAFT) agents with epoxy- and oxetane-functional groups have been synthesized. Two different methods were used to synthesize the epoxy-functional RAFT agent. An acid-functional chain transfer agent was reacted with either epichlorohydrin (EPI) or glycidol to obtain the epoxy-functional RAFT agent. The epoxy-functional RAFT agent synthesized using EPI had a higher yield. Similarly, the oxetane-functional RAFT agent was obtained by reacting a monofunctional reactive oxetane (3-ethyl-3-hydroxymethyl oxetane) (EHMO) with the acid-functional RAFT agent. The presence of epoxy and oxetane groups on the RAFT agent was confirmed using H-1 and C-13 nuclear magnetic resonance techniques. Several acrylate monomers and styrene were polymerized using the novel RAFT agents, and in each case the polydispersity was below 1.1. Poly(butyl acrylate) (PBA) synthesized using the epoxy-functional RAFT agent was reacted with acrylic acid to obtain an acrylate-functional PBA. The oxetane-functional RAFT agent was copolymerized with EHMO to obtain a trithiocarbonylthio macromonomer, which was used for controlled free-radical polymerization of butyl acrylate to obtain a PBA graft copolymer.