Effect of Cu(0) Particle Size on the Kinetics of SET-LRP in DMSO and Cu-Mediated Radical Polymerization in MeCN at 25 °C

Abstract

In order to estimate the effect of Cu(0) particle size in SET-LRP, a comparative analysis of Cu(0)/Me6-TREN-catalyzed polymerization of MA initiated with methyl 2-bromopropionate at 25 °C was performed in DMSO, a solvent that mediates the disproportionation of Cu(I)X, and in MeCN, a solvent in which Cu(I)X does not disproportionate Cu(I)X. Decreasing the Cu(0) particle size results in a marked increase in the apparent rate constant of propagation (kpapp). Decreasing the Cu(0) particle size from 425 to 0.05 μm (50 nm) increases the kpapp by almost an order of magnitude. Regardless of the Cu(0) particle size used, in DMSO a perfect SET-LRP occurs with a first-order polymerization in growing species up to 100% conversion. However, in MeCN the polymerization is not first order in growing species. The results presented here demonstrate that, in addition to the disproportionation of Cu(I)X/L into Cu(0) and Cu(II)X2/L, the particle size of Cu(0) plays a strong role in the kinetics during the entire polymerization.