E.S.R. Spectra of free radicals relevant to methacrylate polymerization

Abstract

Carbon-based free radicals were generated by thermal cleavage of the tetraester Me2C(COOME)-CH2-CMe(COOMe)- CMe (COOMe)-CH2-C(COOMe)Me2 which is a model for head-to-head units in a poly(methyl methacrylate) chain. The resulting electron spin resonance spectrum had higher resolution than the ‘nine-line’ spectrum previously reported; this enabled identification of the component radicals. In the present case, the spectrum was well matched by a summation of spectra of the Me2C(COOME)-CH2-CMe(COOMe) radical and the 1-methoxycarbonyl-1-methylethyl radical Me2-C-COOMe derived from it by loss of methyl methacrylate. Both of these radicals were generated in separate experiments. Radicals were also ge..