Specific Salt Effect of Lithium Perchlorate in Living Anionic Polymerization of Methyl Methacrylate and tert-Butyl Acrylate

Living anionic polymerization of methyl methacrylate can be achieved at −40 °C in tetrahydrofuran (THF) and at −78 °C in toluene/THF (9/1 v/v) using (1,1-diphenylhexyl)lithium as the initiator in the presence of lithium perchlorate (LiClO 4 ) as the additive. Polymerization of tert -butyl acrylate also proceeds in a living manner at −78 o C in THF. Polymers with narrow molecular weight distributions and high initiator efficiencies can be obtained. The use of lithium perchlorate retards the rate of polymerization. The ratio of LiClO 4 to initiator has a greater influence in determining the control of polymerization. The beneficial effect of lithium perchlorate is attributed to its efficient interaction with growing ester−enolate ion pairs.