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...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℃.The tacticity of the resulting poly(MMA)(PMMA)produced without ligands was nearly atactic(rr/mr/mm=22/54/24).However,the use of 18-crown-6 as a ligand afforded predominantly syndiotactic PMMA(rr≈58%),whereas the use of chiral bis(oxazoline)ligands gave slightly isotactic-rich PMMA(mm≈32%).Molecular weight control of PMMA was achieved(Đ=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.展开更多
基金supported by a JSPS KAKENHI Grant-in-Aid for Scientific Research(C)(No.JP22K05209)Transformative Research Areas(A)“Green Catalysis Science for Renovating Transformation of Carbon-Based Research”(No.JP23H04915)for M.U.Scientific Research(A)(No.JP22H00333)for M.K.K.S.acknowledges the“Graduate Program of Transformative Chem-Bio Research(GTR)”at Nagoya University.
文摘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℃.The tacticity of the resulting poly(MMA)(PMMA)produced without ligands was nearly atactic(rr/mr/mm=22/54/24).However,the use of 18-crown-6 as a ligand afforded predominantly syndiotactic PMMA(rr≈58%),whereas the use of chiral bis(oxazoline)ligands gave slightly isotactic-rich PMMA(mm≈32%).Molecular weight control of PMMA was achieved(Đ=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.
