Controlled Free Radical Polymerization Mediated by Cysteine and Glutathione-Based Chain Transfer Agents

摘要

Reversible addition-fragmentation chain transfer (RAFT) polymerization has attracted wide attention since its discovery in 1998.~(1-4 )This technique has moderate reaction conditions and is suitable for a wide range of monomers, so it allows the straightforward synthesis of some complex polymeric architectures such as block, comb and star (co)polymers. On the other hand, the syntheses of peptide-polymer conjugates are of great interest from viewpoint of synthesis and potential applications from nanotechnology to tissue engineering.~(5-10) It has been proven that sequence-defined polypeptides can be used as macroinitiators for nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) processes. Recently, Bomer's group has firstly reported the successful synthesis of polypeptide-polymer (GDGFD-poly(n-butyl acrylate) conjugates using RAFT polymerization.~(15) Among various amino acid and oligopeptides, cysteine and glutathione possess free thiol group and are possibly converted into functional chain transfer agents (CTAs). In this study, novel cysteine and glutathione-based CTAs, 2-acetamido-3- (benzylsulfanylthiocarbonylsulfanyl)propionic acid (ABSPA) and Nacetyl-S-(benzylsulfanylthiocarbonyl)glutathione (ABSG, Scheme 1), were synthesized and used to mediate RAFT polymerization of various vinyl monomers. Based on these chain transfer agents, a series of homopolymers, block copolymers and macromolecular conjugates were synthesized.