Stereoblock polypropyienes bearing isotactic,atactic,and syndictactic polypropylene segments were successfully prepared by dry methylaluminoxane activated binary catalysts system,Ph2CFluCpZrCl2 and {Me2Si(2,5-Me2-3-(2...Stereoblock polypropyienes bearing isotactic,atactic,and syndictactic polypropylene segments were successfully prepared by dry methylaluminoxane activated binary catalysts system,Ph2CFluCpZrCl2 and {Me2Si(2,5-Me2-3-(2-MePh)-cyclopento[2,3-b]thiophen-6-yl)2}ZCl2,in the presence of iBu3Al as a chain shutting agent.by studying the catalyst activity,chain transfer efficiency,and reversility of chain transfer reaction of each catalyst system,as well as the molecular weight and polydispersity of the resulting polymers,the allyl exchange reactions between the zirconium catalyst and different main-group metal alky were estimated,respectvely.Based on the optimized react condition,the chain shuttling polymerization was conducted by binary catalyst system in the presence of iBu3Al under both atmospheric and high pressure.Resultant polymers were identified as stereoblock polypropylenes according to microstructure and physical properties analyses by 13C{1H}-NMR,DsC,and GPC.展开更多
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the National Natural Science Foundation of China(No.21574097).
文摘Stereoblock polypropyienes bearing isotactic,atactic,and syndictactic polypropylene segments were successfully prepared by dry methylaluminoxane activated binary catalysts system,Ph2CFluCpZrCl2 and {Me2Si(2,5-Me2-3-(2-MePh)-cyclopento[2,3-b]thiophen-6-yl)2}ZCl2,in the presence of iBu3Al as a chain shutting agent.by studying the catalyst activity,chain transfer efficiency,and reversility of chain transfer reaction of each catalyst system,as well as the molecular weight and polydispersity of the resulting polymers,the allyl exchange reactions between the zirconium catalyst and different main-group metal alky were estimated,respectvely.Based on the optimized react condition,the chain shuttling polymerization was conducted by binary catalyst system in the presence of iBu3Al under both atmospheric and high pressure.Resultant polymers were identified as stereoblock polypropylenes according to microstructure and physical properties analyses by 13C{1H}-NMR,DsC,and GPC.
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.
