Living Radical Polymerization of Alkyl Methacrylates with Ruthenium Complex and Synthesis of Their Block Copolymers

Living radical polymerizations of ethyl and n-butyl methacrylates (EMA and BMA, respectively) have been achieved with ternary initiating systems that consist of carbon tetrachloride, tris(triphenylphosphine)ruthenium dichloride [RuCl2(PPh3)3], and aluminum compounds such as MeAl(ODBP)2 (ODBP, 2,6-di-tert-butylphenoxy) and Al(OiPr)3 in toluene at 60−80 °C. The produced polymers had narrow molecular weight distributions (MWDs) (M̄ w/M̄ n = 1.2−1.5) and controlled molecular weights that are nearly proportional to monomer conversion. Sequential living polymerizations of these methacrylates from methyl methacrylate (MMA) afforded AB-type block copolymers with narrow MWDs (M̄ w/M̄ n ∼ 1.2). Further addition of MMA into the living AB block copolymers gave ABA-type triblock copolymers poly(MMA-b-BMA-b-MMA).