Degree of polymerization and chain transfer in methyl methacrylate

Abstract

The chain-transfer constants of twenty-six solvents in the polymerization of methyl methacrylate have been calculated, using Mayo's equation for chain-transfer reaction, from the measured values of degree of polymerization of the product formed in these solvents at different concentrations at 80°C. The increase in transfer constants in hydrocarbons, alcohols, ketones, acids and ester may be effectively accounted for by the the increased polarization of the C-H bond at the α-position, by adjacent electron-attracting groups. In the case of chloro-compounds the activity has been found to depend not on the number of halogen atoms in the molecule as was suggested by Mayo but on the extent of C-Cl bond forces. Further, it is shown that simple chain transfer reactions with solvents cannot fully account for all the observed discrepancies in the kinetic measurements in solution.