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Kinetics of Dithiobenzoate‐Mediated Methyl Methacrylate Polymerization
Author(s) -
Sidoruk Alana,
Buback Michael,
Meiser Wibke
Publication year - 2013
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201300247
Subject(s) - chain transfer , polymerization , polymer chemistry , chemistry , methyl methacrylate , raft , radical polymerization , kinetics , reaction rate constant , reversible addition−fragmentation chain transfer polymerization , activation energy , electron paramagnetic resonance , photochemistry , polymer , organic chemistry , nuclear magnetic resonance , physics , quantum mechanics
Abstract The equilibrium constant, K eq , 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: E a ( k ad ) – E a ( k frag ) ≈ −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 K eq , due to slow k ad , are responsible for rate retardation being absent in dithiobenzoate‐mediated MMA polymerization.