Block Copolymer Synthesis through the Use of Switchable RAFT Agents

Abstract

The use of "switchable" RAFT agents in expanding the use of RAFT polymerization in block copolymer synthesis is decsribed. 'N'-(4-pyridinyl)-'N'-methyldithiocarbamates provide excellent control over polymerization of less activated monomers (LAMs) (e.g., vinyl acetate, 'N'-vinylcarbazole), and, after addition of one equivalent of a protic or Lewis acid, become effective in controlling polymerization of more activated monomers (MAMs) (e.g., styrene, methyl methacrylate). They thus allow a convenient synthesis of polyMAM-'block'-polyLAM with narrow molecular weight distributions. Advantages, limitations and factors effecting the scope of the process are discussed.