New Chain Transfer Agents for Radical Polymerization Based On the Addition-fragmentation Mechanism

This study describes 15 compounds with allylic or pentadienic structure carrying either captodative (ed) carbon- or heteroatom substituents as potential radical leaving groups in an addition-fragmentation reaction. Their experimental evaluation as chain-transfer agents (CTA) was achieved in radical polymerization of styrene and methyl methacrylate. The a(cd-substituted methyl)acrylates 9 and 11 were more efficient than the t-thioether 10 in lowering molecular weight of polystyrene. The dienes are particularly effective and provide macromonomers with terminal diene functions which are very useful for further copolymerization with a variety of vinyl monomers.