Manganese-Based Controlled/Living Radical Polymerization of Vinyl Acetate, Methyl Acrylate, and Styrene: Highly Active, Versatile, and Photoresponsive Systems

The highly active, versatile, and photoresponsive controlled/living radical polymerizations were developed using Mn2(CO)10 coupled with an alkyl iodide initiator (R−I) under weak visible light. The photoinduced polymerization of vinyl acetate (VAc) proceeded very fast even at 40 °C with a catalytic amount of Mn2(CO)10 (0.025 mol % of VAc or 5.0 mol % of R−I) and completed within a few hours to give the polymers with controlled molecular weights up to 105. The controlled polymerization was photoresponsive; that is, the polymerization proceeded only during the lighting period while maintaining the controlled molecular weights for the entire period. This system was also effective in controlled radical polymerizations of conjugated monomers such as styrene and methyl acrylate in conjunction with an appropriate alkyl iodide initiator. The contributions of the metal-catalyzed and the degenerative iodine transfer processes were also examined by analyzing the model reactions.