Assessing the RAFT Equilibrium Constant via Model Systems: An EPR Study
Authors:
- 7 July 2011
- journal article
- research article
- Published by Wiley in Macromolecular Rapid Communications
- Vol. 32 (18) , 1490-1494
Abstract
Reversible addition‐fragmentation chain transfer (RAFT) equilibrium constants, Keq, for the model system cyano‐iso‐propyl dithiobenzoate (CPDB) – cyano‐iso‐propyl radical (CIP) have been deduced via electron paramagnetic reso1494nce (EPR) spectroscopy. The CIP species is produced by thermal decomposition of azobis‐iso‐butyronitrile (AIBN). In solution of toluene at 70 °C, Keq has been determined to be (9 ± 1) L · mol−1. Measurement of Keq = kad/kβ between 60 and 100 °C yields ΔEa = (–28 ± 4) kJ · mol−1 as the difference in the activation energies of kad and kβ. The data measured on the model system are indicative of fast fragmentation of the intermediate radical produced by addition of CIP to CPDB. magnified imageKeywords
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