Vinyl polymerization. V. Synthesis of graft polymers from brominated poly (styrene)

Abstract

Vinyl monomer [methyl methacrylate (MMA), or ethyl methacrylate (EMA) or methyl acrylate (MA)] was polymerized in benzene solution with benzoyl peroxide as catalyst and in the presence of varying amounts of bromopoly (styrene) (Br PS). Branching occurred by chain transfer reaction of the growing polymer radicals with bromine atoms of the bromopoly (styrene) backbone, followed by initiation of polymerization by the Br PS radicals thus obtained. The chain transfer constants of the branching reaction and the degree of grafting were determined and by suitable correlation of the two, k_p /(k_t)^½ for the grafting reactions were evaluated. The graft polymers were isolated by fractional precipitation, and were characterized by IR spectra and molecular weight determination by osmotic pressure measurements. The high values of chain transfer constant, molecular weight of the graft polymers much in excess of the backbone Br PS, the order of magnitudes or second virial coefficients, etc., proved the formation of graft polymers.