Synthesis of Well-Defined Polythiol Copolymers by RAFT Polymerization

A simple methodology to prepare well-defined polythiol copolymers by RAFT polymerization was developed. A methacrylate monomer carrying a S-alkyl-O-ethyl xanthate moiety as thiol protecting group was prepared in two high yield steps. Polythiols were obtained by copolymerizing the, functional methacrylate and subsequent aminolysis of the. protecting groups. Model reactions and polymerizations showed that the S-alkyl-O-ethyl dithiocarbonate functionality h is fully compatible with the RAFT polymerization of methacrylates and did not induce any side reactions. Functionalization of polythiol copolymers was done via thiol-ene addition, Michael addition and thiol-disulfide exchange. Thiol deprotection and functionalization were done in one pot for Michael addition and thiol-disulfide exchange. A complete conversion of thiol groups was observed for all three types of reactions, exemplifying the potential of polythiol copolymers for the preparation of functional materials.