EPR Investigations into the Kinetics of Trithiocarbonate‐Mediated RAFT‐Polymerization of Butyl Acrylate

Abstract

Electron paramagnetic resonance (EPR) spectroscopy is used for measuring rate coefficients of addition, kad, and fragmentation, kβ, together with the associated equilibrium constants, Keq, for butyl acrylate polymerizations mediated by S‐ethyl propan‐2‐ylonate‐S’‐propyl trithiocarbonate (EPPT) and by S‐S’‐bis(methyl‐2‐propionate) trithiocarbonate (BMPT). Experiments at −40 °C yield kad = (3.4 ± 0.3) × 106 L mol−1 s−1, kβ = (1.4 ± 0.4) × 102 s−1, and Keq = (2.6 ± 0.8) × 104 L mol−1 for EPPT and kad = (4.1 ± 0.9) × 106 L mol−1 s−1, kβ = (4.5 ± 0.5) × 101 s−1, and Keq = (8 ± 4) × 104 L mol−1 for BMPT. The Keq values are in satisfactory agreement with data from ab initio calculations. image