Kinetics of diffusion-controlled copolymerization systems

Abstract

Kinetics of diffusion-controlled copolymerization systems, (i) vinyl acetate and isobutyl methacrylate, (ii) methyl methacrylate and methyl acrylate and (iii) methyl methacrylate and ethyl methacrylate, have been investigated at 30 and 60° C utilizing the equations developed by Atherton and North. The observed termination constant for system (i) at 30°C decreases monotonically with increasing concentration of vinyl acetate in the feed up to about 90 mole % vinyl acetate and then increases rapidly at higher concentration of vinyl acetate. At 60°C, the termination constant remains roughly constant at low vinyl acetate content and also approaches the ideal behaviour. The termination rate for system (ii) at 60°C remains constant up to about 82 mole % methyl acrylate while for system (iii) at 30°C it increases continuously with methyl methacrylate concentration. These results have been interpreted in terms of the relative stiffness of polymeric chains as the controlling factor of termination reactions and support the diffusion-controlled termination mechanism of Benson and North.