Use of ascorbic acid as reducing agent for synthesis of well-defined polymers by ARGET ATRP

The use of ascorbic acid as reducing agent for synthesis of methyl acrylate (MA) by activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) is described. The ARGET ATRP of MA in the presence of various amounts of CuBr2/tris(2-(dimethylamino)ethyl)amine (Me6TREN) complexes and ascorbic acid under homogeneous conditions in N,N-dimethylformamide (DMF) and under homogeneous conditions shows the retention of active chain-end functionality in the polymers. The ascorbic acid can be successfully applied to ARGET under heterogeneous conditions, when its limited solubility in reaction medium allows a controlled ARGET ATRP. It was observed that a higher amount of reducing agent, ascorbic acid, resulted in a higher polymerization rate. The higher polymerization rate indicates that some contribution of the heterogeneous redox reaction between the Cu(II) catalysts and the surface of the solid ascorbic acid may also occur in addition to a homogeneous reaction with soluble ascorbic acid.