Controlled grafting of poly(styrene-ran-n-butyl methacrylate) to isotactic polypropylene with nitroxide-mediated polymerization

Abstract

A nitroxide (2,2,6,6-tetramethylpiperidin-1-oxyl, TEMPO) mediated polymerization method was applied to the graft polymerization of styrene (ST)/n-butyl methacrylate (BMA) to isotactic polypropylene (PP). PP peroxides produced by γ-irradiation in air were used as macroinitiator for grafting. The molecular characteristics of grafted and free poly(ST-r-BMA) chains were analysed by gel permeation chromatography, NMR and IR measurements. The molecular weight of grafted poly(ST-r-BMA) cleaved from PP was slightly higher than that of free poly(ST-r-BMA) generated simultaneously in the reaction system. Polydispersities of these polymers were narrow, indicating that grafting proceeded in a living fashion. The incorporated amount of BMA into grafted poly(ST-r-BMA) was smaller than that of free poly(ST-r-BMA). It is considered that the local concentration of BMA around propagating ends of graft poly(ST-r-BMA) was lower than that around free poly(ST-r-BMA) because PP cannot be dissolved in BMA monomer but in ST monomer at the polymerization temperature.