SP–PLP–EPR Measurement of Cu<sup>II</sup>-Mediated ATRP Deactivation and Cu<sup>I</sup>‑Mediated Organometallic Reactions in Butyl Acrylate Polymerization

The SP–PLP–EPR technique has been used to measure Cu<sup>II</sup>-mediated ATRP deactivation and Cu<sup>I</sup>-mediated organometallic reactions for butyl acrylate (BA) polymerization. The deactivation rate is by more than 1 order of magnitude higher than in dodecyl methacrylate (DMA) polymerization, thus enabling well-controlled ATRP despite the enhanced BA propagation rate. The organometallic reaction of Cu<sup>I</sup> with BA radicals was found to play a role only with highly active Cu catalysts, as demonstrated for the Cu/TPMA-mediated ATRP of BA.