Some kinetic aspects of radical copolymerization: influence of the reaction medium on the reactivity ratios

The reactivity ratios for the free radical copolymerization of styrene and methyl methacrylate at 50°C have been evaluated in dioxane, acetone and dimethylformamide solutions. In all these systems there is a marked solvent effect on both r₁ and r₂, which can be correlated to the variation in the dielectric constant of the solvent. The role of solvents in enhancing the polarization of growing chains and the alternation tendency is discussed.