Terminally Functionalized Isotactic Polypropylenes: New Synthetic Routes via Controlled Chain Transfer Reaction

摘要

In the study of olefin coordination/insertion polymerization, an investigation of chain transfer reactions is very important because it relates to the control of molecular weights and end group structures of resultant polyolefins. Recently some metallocenes incuding rac-Et[2-~tBuMe2SiO-(Ind)]2ZrCl2, rac-Et[2-~tBuMe2SiO-(Ind)]2HfCl2 and rac-Me2Si(2-Me-4-tBu-C5H2)2ZrCl2 combined with MAO were found to possess a major aluminum chain transfer reaction in their respective propylene polymerizations. When AlEt3 was used in conjunction with (Ph3CB(C6F5)4 as the cocatalyst, AlEt3 was found to initiate significant chain transfer reaction even in propylene polymerization with some conventional metallocenes including rac-Et(Ind)2ZrCl2, rac-Me2Si(Ind)2ZrCl2 and i-Pr(Cp)(Flu)ZrCl2.