Synthesis of End-Functional Poly(vinyl acetate) by Cobalt-Mediated Radical Polymerization

Poly(vinyl acetate) (PVAc) chains prepared by cobalt-mediated radical polymerization in the presence of cobalt(II) acetylacetonate (Co(acac) 2 ) were quenched by radical scavengers, such as thiol compounds and nitroxides, to displace the covalently bonded Co(acac) 2 moiety and to end-cap them with a reactive group. The cobalt complex was completely removed by filtration, as confirmed by the induction coupled plasma (ICP) analysis of the polymer before and after treatment. Growing poly(vinyl acetate) chains can be end-functionalized either by addition of an appropriately functionalized nonpolymerizable olefin or by displacement of the Co(acac) 2 moiety by a functionalized nitroxide. This strategy allows PVAc to be synthesized with a predictable molecular weight, a reasonably low polydispersity ( M w / M n ∼ 1.1−1.3), and a functional ω end group, e.g., hydroxyl and epoxy.