Regiospecific Radical Polymerization of Vinyl Methacrylate in the Presence of Lewis Acids into Soluble Polymers with Pendent Vinyl Ester Substituents

Abstract

The regiospecific radical polymerization of vinyl methacrylate (VMA), a divinyl compound with two different radically polymerizable double bonds, was investigated in the presence of Lewis acids, such as SnCl4, EtnAlCl3−n, and RnAl(ODBP)3−n [R = Me, Et, i-Bu; ODBP = 2,6-di-tert-butylphenoxy]. The polymerization with α,α-azobis(isobutyronitrile) (AIBN) in the presence of aluminum-based Lewis acids gave soluble polymers, in which the methacryloyl group was selectively polymerized, while insoluble polymer gels were obtained without Lewis acids or with SnCl4. When using monoalkylaluminum bulky diphenoxides [RAl(ODBP)2], the highly regiospecific radical polymerization significantly proceeded with a high conversion (>85%) to give soluble polymers with quantitatively remaining vinyl ester pendants and a relatively high molecular weight (Mn ≥ 104). The copolymerization of VMA with methyl methacrylate in the presence of EtAl(ODBP)2 induced the simultaneous consumption of both monomers at almost the same rate to dir...