The effect of preferential solvation on the kinetic order of alkyl methacrylate polymerization in benzene

The kinetic order of the polymerization of n-alkylmethacrylates with respect to monomer in benzene (fractional and greater than one) has been interpreted as due to concentration changes of a monomer at the site of reaction caused by preferential solvation of the growing macromolecule by benzene. Correlation of the rates of polymerization at 30° with determined monomer concentrations in the close vicinity of the polymer chain gives kinetic orders of 1±0.05 for both n-butyl- and n-dodecyl-methacrylates. The coefficient of preferential solvation at 30° for the polymers investigated is between 0.1 and 0.4 [cm3 g−1] depending on the composition of the mixture of benzene and monomer. The coordination numbers 3 and 4 needed for calculation of the composition of the solvent in the solvating layer correspond to theoretical views on polymer solutions.