The effects of abstractable hydrogen in radical photopolymerization of maleate/vinyl ether monomers studied with EPR and photo‐RTIR

In this contribution, the influence of abstractable hydrogen on the kinetics of photopolymerized vinyl ether/maleate monomer formulations is reported. The effects of chain transfer on the polymerization rate were studied with photo real‐time Infra Red (IR) for formulations composed of equimolar amounts of diethyl maleate (DEMA) and three different vinyl ethers; methyl hexyl vinyl ether where the abstractable hydrogens adjacent to the vinyl functionality have been replaced with methyl groups, ethyl hexyl vinyl ether (EHVE) which has two easily abstractable α‐hydrogens and triethylene glycol methyl vinyl ether (TEGMVE), which has several abstractable hydrogens. Four conclusions are drawn from these studies: (i) the vinyl ether/maleate kinetics differs significantly from the classical expression R_p = KI^0.5, with recorded exponential factors of 0.84 ± 0.04 in the absence of easily abstractable hydrogens; (ii) the presence of abstractable hydrogens significantly changes the kinetics of vinyl ether/maleate polymerizations with recorded exponential factors of 0.55 ± 0.04 for EHVE/DEMA and 0.70 ± 0.04 for TEGMVE/DEMA; (iii) the presence of easily abstractable hydrogens leads to a preferential consumption of maleates; and (iv) electron paramagnetic resonance studies show that vinyloxy‐like radicals constitute the majority of the radicals in the systems with easily abstractable hydrogens. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2810–2816, 2010