Continuous ARGET ATRP of Methyl Methacrylate and Butyl Acrylate in a Stirred Tank Reactor

Activator regenerated by electron transfer atom-transfer radical polymerization of butyl acrylate and methyl methacrylate was successfully adapted from a batch process to a continuous stirred tank reactor (CSTR) with 50 ppm copper. A series of batch polymerizations were first performed to identify a solvent mixture to enhance the polymerization rate, maintain chain livingness, and eliminate unsteady-state behavior caused by the precipitation of copper(II) complexes. The batch formulations were run in a CSTR with mean residence times of 60, 90, and 120 min, with steady-state behavior reached after four residence times. The apparent rate coefficient in the CSTR experiments was higher than that in batch polymerizations, likely because of a higher steady-state reducing agent concentration in the CSTR, which shifted the copper(I)/copper(II) ratio in favor of the activating species. Polymer chain extensions showed good living characteristics, demonstrating CSTRs as a viable platform for industrial-scale controlled radical polymerization.