Fe(0) Powder/CuBr2-Mediated "Living"/Controlled Radical Polymerization of Methyl Methacrylate and Styrene at Ambient Temperature

The combination of zero-valent iron (Fe(0) powder) and copper(II) bromide was used to mediate the polymerization of methyl methacrylate (MMA) or styrene (St) at 25 degrees C. The results demonstrated that the solvent played an important role on the polymerization rate and molecular-weight control. The polymerization in toluene displayed a poorly controlled process with remarkably low polymerization rate. With dimethyl sulfoxide (DMSO) as solvent, the polymerization proceeded in a relatively high rate, and the number-average molecular weights were controlled especially at higher conversion. High conversions (80%) of St could be achieved with narrow molecular weight distributions in DMSO at 25 degrees C. It was supposed that Fe(0) played a dual role, the activator for the generation of active radical and the reducing agent for CuBr2.