Macromolecular Rapid Communications, Vol.33, No.15, 1273-1279, 2012
"Assessing the RAFT Equilibrium Constant via Model Systems: An EPR Study" - Response to a Comment
We have presented an EPR-based approach for deducing the RAFT equilibrium constant, Keq, of a dithiobenzoate-mediated system [Meiser, W. and Buback M. Macromol. Rapid Commun. 2011, 32, 1490]. Our value is by four orders of magnitude below Keq from ab initio calculations for the identical monomer-free system. Junkers et al. [Macromol. Rapid Commun. 2011, 32, 1891] claim that our EPR approach would be model dependent and our data could be equally well fitted by assuming slow addition of radicals to the RAFT agent and slow fragmentation of the so-obtained intermediate radical as well as high cross-termination rate. By identification of all side products, our EPR-based method is shown to be model independent and to provide reliable Keq values, which demonstrate the validity of the intermediate radical termination model.
Keywords:ESR;EPR;intermediate radical termination;"missing step";NMR;reversible addition fragmentation chain transfer