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 FeII 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 FeII. The associated rate coefficient was measured in an extended temperature range for both acrylate and methacrylate polymerization. Detailed knowledge about the kinetics of FeII-catalyzed radical termination may be of general importance for iron-mediated ATRPs of acrylates.