The reactivity of maleic anhydride toward the 1-phenylethyl radical

The behaviour of the 1-phenylethyl radical as an initiating species was investigated using the end group method of Bevington et al. for a number of copolymerisations of methyl methacrylate with maleic anhydride and similar species. A strong selectivity for addition of the 1,2 disubstituted monomer was found in each case. The reactivity ratios obtained for addition of the 1-phenylethyl radical to styrene and maleic anhydride, when compared with published equivalents for the poly(styrene) radical, showed addition to the 1-phenylethyl radical to be more selective by a factor of approximately two. Similar results were found for each of the other species examined and it is suggested a penultimate effect of steric origin is responsible for the decreased selectivity of the poly(styrene) radical. No significant solvent effect was found on the reactivity of the 1-phenylethyl radical in the copolymerisation of methyl methacrylate and maleic anhydride. (C) 1998 Elsevier Science Ltd. All rights reserved.