Dimanganese decacarbonyl/2-cyanoprop-2-yl-1-dithionaphthalate: toward sunlight induced RAFT polymerization of MMA

Methyl methacrylate was polymerized in the presence of dimanganese decacarbonyl [Mn₂(CO)₁₀]/2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) via a photo-induced controlled radical polymerization under visible (green LED with λ_max of 565 nm) or sunlight irradiation at a moderate temperature. The manganese carbonyl [Mn₂(CO)₁₀] served as the light absorbing component, whereas 2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) served as pseudo-alkyl halide initiator and mediating agent. The polymerization showed the characteristic behaviour of a living polymerization such as linear kinetics; the molecular weight of the polymers linearly increased with monomer conversion, and the obtained polymers showed a narrow molecular weight distribution under appropriate conditions. The obtained polymers exhibited high degree of chain end functionality, which could be used for further chain extensions, either through a traditional thermally initiated RAFT polymerization or through a light-irradiated LRP in the presence of [Mn₂(CO)₁₀]. The possibility of stopping and restarting the polymerization process was realized simply by turning off or on the LED light.