Chemical reactivity and conformational properties of growing chains. Part 2.—Effect of the reaction medium on the termination kinetics in styrene + methyl methacrylate solution copolymerization

Abstract

The solution copolymerization of styrene and methyl methacrylate in acetone, in dimethylformamide and in dioxan has been interpreted on the basis of a proposed model which includes chain end mobility and chemical reactivity. For all systems the derived equation giving the overall rate of copolymerization is in agreement with the experimental data. The effect of the reaction medium on bimolecular termination can be represented by the dependence of the rate-conditioning segmental rearrangement on medium fluidity.

There is a marked solvent effect on the propagation rate coefficients. It is more pronounced for styrene than for methyl methacrylate and it shows an opposite trend for the two monomers: compared to the value for bulk polymerization k_p for styrene is decreased, whereas k_p for methyl methacrylate is increased in solution.