The polymerization of methyl methacrylate and butyl acrylate initiated by azo-bis-isobutyronitrile in the presence of metal-containing monomers (p-methylstyrene-, stilbene-and α-methylstyrenechromiumtricarbonyl) was studied. Kinetic parameters (i.e. the decrease in the autoacceleration during the polymerization of acrylic monomers, its shift towards a high conversion region in the presence of α-methylstyrenechromiumtricarbonyl, a linear dependence of the molecular weight of a polymethyl methacrylate and the shift of molecular-weight distribution curves to a high molecular weight region with conversion) demonstrate the influence of vinylarenetricarbonyl complexes of chromium on basic steps of polymerization. It is important to note that the above organometallic compounds enable the controlled synthesis of polymers under temperature conditions (50-70 • C) corresponding to those of the industrial polymer production.

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The organometallic monomers styrenetricarbonylchromium and p-methylstyrenetricarbonylchromium were copolymerized in ethyl acetate solutions with methyl methacrylate and butyl acrylate using azobisisobutyronitrile at 50°C and a binary system including di-tert-butylperoxytriphenylantimony at 30°C as the freeradical initiators. Comonomers are proposed to form a molecular complex based on the results of ultraviolet and electron spin resonance spectroscopy. A kinetic study shows that chromiumcontaining monomers at high concentrations in the mixture reduce the rate of copolymerization. The addition of styrenetricarbonylchromium to butyl acrylate significantly slows down the autoacceleration. The reactivity ratios of the comonomer pairs, namely, styrenetricarbonylchromium-methyl methacrylate, styrenetricarbonylchromium-butyl acrylate and p-methylstyrenetricarbonylchromium-methyl methacrylate, were determined using the method of Kelen-Tudos for low conversion polymerizations.