Abstract
AbstractThe equilibrium constant, Keq, of the reversible addition–fragmentation chain transfer (RAFT) model system methyl methacryl dithiobenzoate (MMADB) and of methyl methacrylate (MMA) polymerization mediated by MMADB is studied via electron paramagnetic resonance (EPR) spectroscopy in the range 70 to 110 °C and at −40 °C, respectively. The measured difference in activation energy of the addition and fragmentation steps is: Ea(kad) – Ea(kfrag) ≈ −36.6 kJ mol−1. Significant amounts of “missing step” products from reaction of the cross‐termination product with a methyl methacrylyl radical are found. The fast “missing step” reaction and low Keq, due to slow kad, are responsible for rate retardation being absent in dithiobenzoate‐mediated MMA polymerization.magnified image
Published Version
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