Tricarbonylchromium complexes of styrenes in radical copolymerization

The organometallic monomers styrenetricarbonylchromium and p-methylstyrenet ricarbonylchromium were copolymerized in ethyl acetate solutions with methy l methacrylate and butyl acrylate using azobisisobutyronitrile at 50 degree sC and a binary system including di-tert-butylperoxytriphenylantimony at 30 degreesC as the free-radical initiators. Comonomers are proposed to form a molecular complex based on the results of ultraviolet and electron spin re sonance spectroscopy. A kinetic study shows that chromium-containing monome rs at high concentrations in the mixture reduce the rate of copolymerizatio n. The addition of styrenetricarbonylchromium to butyl acrylate significant ly slows down the autoacceleration, The reactivity ratios of the comonomer pairs, namely, styrenetricarbonyl-chromium-methyl methacrylate, styrenetric arbonylchromium-butyl acrylate and p-methylstyrenetricarbonylchromium-methy l methacrylate, were determined using the method of Kelen-Tudos for low con version polymerizations, Copyright (C) 2001 John Wiley & Sons, Ltd.