Highly syndiotactic poly(methyl methacrylate) with narrow molecular weight distribution formed by tert-butyllithium-trialkylaluminium in toluene

Summary Polymerization of MMA with t-C₄H₉Li in toluene in the presence of trialkylaluminum(alkyl=methyl, ethyl, butyl, isobutyl, and octyl) was examined at various Al/Li ratios. Triethyl-, tributyl and trioctylaluminums worked quite effectively in the polymerization to give highly syndiotactic PMMA with narrow molecular weight distribution (MWD) at the Al/Li ratio of 3 and higher than 3. The highest syndiotacticity of 96% was attained with t-C₄H₉Li/(n-C₈H₁₇)₃Al (1/3) at –93°C. The polymerization was initiated by t-C₄H₉ anion and proceeded in a living manner. The structure of the syndiotactic PMMA is chemically identical to that of isotactic PMMA prepared with t-C₄H₉MgBr. Consequently, highly isotactic and syndiotactic PMMAs with narrow MWD and with the same chemical structure from -end to -end were obtained.