Anionic Polymerization of Methyl Methacrylate with the Aid of Lithium Trimethylsilanolate (Me 3 SiOLi) ‐ Superior Control of Isotacticity and Molecular Weight

Highly isotactic‐specific polymerization of methyl methacrylate (MMA) was developed by using a combined anionic initiator comprising α ‐lithioisobutyrate (Li‐ i PrIB) and a large excess of lithium trimethylsilanolate (Me 3 SiOLi), which afford, in particular, isotactic poly(methyl methacrylate) (PMMA) with isotactic triad content of up to 99.5% under the adjusted polymerization conditions. The polymerization system also exhibited a high activity such that isotactic PMMA with $\overline M _{\rm n}$ of over 800 000 and narrow molecular weight distribution ( $\overline M _{\rm w} /\overline M _{\rm n}$  < 1.2) was obtained.