Reverse iodine transfer radical copolymerization of vinyl acetate and dibutyl maleate: synthesis and characterization of alternating and block copolymers

Reverse iodine transfer radical bulk homo- and copolymerization of vinyl acetate (VAc) and dibutyl maleate (DBM) was performed in the presence of molecular iodine and 2,2^׳-azobis(isobutyronitrile) at 70 °C. It was found from (micro)structural analysis by ¹H-NMR and ¹³C-NMR spectroscopies that depending on the mole fraction of comonomers in the initial feed, P(VAc-co-DBM)-b-PVAc block terpolymer or P(VAc-alt-DBM) alternating copolymer can be produced. GPC results showed that copolymerization proceeds via controlled characteristics, i.e. with a predictable molecular weight and relatively narrow molecular weight distribution (MWD). Under similar conditions, reaction time was reduced to about one-fourth of the iodine transfer radical polymerization of these comonomers and molecular weight of the copolymer increased significantly. It was found from TGA thermograms that incorporation of DBM units into the copolymer chains increases thermal stability of the VAc-based polymers. TGA thermograms also allowed us to distinguish various structures of the copolymers produced at the various conditions of the initial feed.