Studies in copolymerization I. The evaluation of the kinetic coefficients for the copolymerization of styrene and methyl methacrylate

Abstract
The benzoyl peroxide photosensitized copolymerization of styrene and methyl methacrylate has been studied with the object of determining all the rate coefficients. The variation of rate of copolymerization with monomer composition has been determined under standard conditions, the reaction being followed dilatometrically. The rate of initiation has also been studied as a function of monomer composition; it was found that the introduction of small quantities of styrene markedly lowered the rate of initiation. From a combination of these two studies, the absolute velocity coefficients for all the various steps have been measured. For the reaction at 30° C, it was found that the rate coefficient for the termination of two unlike radicals ( k tab = 2.06 x 10 8 ) was much greater than those for the termination of two styrene radicals ( k taa = 8 x 10 8 ) or of two methyl methacrylate radicals ( k tbb = 2.7 x 10 7 ). Finally, some data are presented on the osmotic behaviour of copolymers of styrene and methyl methacrylate in benzene solution.