Co(acac)2 mediated controlled radical copolymerization of vinyl acetate and methyl acrylate initiated by benzoyl peroxide

Abstract

Cobalt mediated radical copolymerization of vinyl acetate (VAc) and methyl acrylate (MA) was successfully performed in the presence of cobalt(II) acetylacetonate (Co(acac)2), dimethylformamide (DMF) and benzoyl peroxide (BPO) as catalyst, cobalt coordinating agent and initiator, respectively, at 45°C. The individual monomer conversion and comonomer composition of copolymers were determined by 1H NMR spectroscopy. Molecular weight (Mn) and its distribution (Mw/Mn) were analyzed by GPC technique. The time dependence of ln[M]0/[M], the variation of molecular weight with respect to the conversion, and molecular weight distribution of copolymers were studied to evaluate controlled characteristics of copolymerization. It was found that Co(acac)2 successfully mediated the radical copolymerization of VAc and MA. Moreover, copolymer molecular weight and copolymerization rate increased with increasing initial MA ratio. The spectroscopy analysis revealed VAc content in the copolymer increased with conversion regardless of VAc initial ratio, indicating a gradient sequence distribution of the copolymer.