SP–PLP–EPR Measurement of Iron-Mediated Radical Termination in ATRP

Radical termination was studied in the presence of iron­(II) bromide, which is an attractive catalyst for atom-transfer radical polymerization (ATRP). Termination rate is measured in both the absence and presence of Fe^II via time-resolved EPR spectroscopy of propagating radicals produced by applying laser single pulses. This novel method quantifies the catalytic termination of two propagating radicals by Fe^II. The associated rate coefficient was measured in an extended temperature range for both acrylate and methacrylate polymerization. Detailed knowledge about the kinetics of Fe^II-catalyzed radical termination may be of general importance for iron-mediated ATRPs of acrylates