Proton Transfer Anionic Polymerization of Methyl Methacrylate with Ligands for Dual Control of Molecular Weight and Tacticity.

Dual control of the molecular weight and tacticity in proton transfer anionic polymerization (PTAP) of methyl methacrylate (MMA) was investigated by using various ligands in the presence of a bulky potassium base catalyst and an organic compound with a weakly acidic C-H bond as dormant species in toluene at 0 °C. The tacticity of the resulting poly(MMA) (PMMA) produced without ligands was nearly atactic (// = 22/54/24). However, the use of 18-crown-6 as a ligand afforded predominantly syndiotactic PMMA ( ≈ 58%), whereas the use of chiral bis(oxazoline) ligands gave slightly isotactic-rich PMMA ( ≈ 32%). Molecular weight control of PMMA was achieved ( = 1.1-1.2) by adding 1,1-diphenylethanol as a reversible terminator while maintaining control of the tacticity with the above ligands. Stereoblock PMMA consisting of atactic and syndiotactic segments was successfully synthesized via sequential PTAP using macroinitiator/macro-CTA methods.