Metal Complex-Mediated Living Radical Polymerization: Features, Scope, and Precision Polymer Synthesis

Abstract

The scope, mechanism, and initiating systems of transition metalmediated living radical polymerization have been discussed in light of the authors' recent results. For example, a radical propagation is strongly suggested for the polymerization of methyl methacrylate (MMA) with the dichloroacetophenone/RuCl₂(PPh₃)₃/Al(OiPr)₃ initiating system, because it is immediately terminated by radical quenchers such as galvinoxyl and TEMPO, but is immune to protic polar compounds such as water and methanol. The latter feature also leads to living radical polymerization in methanol and other alcohols and even in water. The product polymers therein are shown to possess a tertiary chloride ω-end that remains intact after work-up with acid and water and can renitiate living polymerization when treated with RuCl₂(PPh₃)₃ and Al(OiPr)₃. The paper also discusses the precise synthesis of star, telechelic, and end-functionalized polymers by the ruthenium-mediated living radical polymerizations with novel multifunctional and functionalized initiators.