Switch from Anionic Polymerization to Coordinative Chain Transfer Polymerization: A Valuable Strategy to Make Olefin Block Copolymers

Anionic polymerization of butadiene or/and styrene is performed with lithium initiators, functional or not. The polymer chains are subsequently transferred to magnesium. The resulting polymeryl‐magnesium compounds were combined with {(Me2Si(C13H8)2)Nd(μ‐BH4)[(μ‐BH4)Li(THF)]}2 metallocene complex to act as macromolecular chain transfer agents (macroCTAs) in coordinative chain transfer polymerization (CCTP) of ethylene (E) or its copolymerization (CCTcoP) with butadiene (B). Block copolymers were produced for the first time by this switch from anionic polymerization to CCTP. Hard and soft blocks such as PB, polystyrene (PS), poly(styrene‐co‐butadiene) (SBR) obtained by anionic polymerization and PE or poly(ethylene‐co‐butadiene) (EBR) produced by CCT(co)P were combined and the corresponding structures were characterized. Successive anionic polymerization and transmetallation reaction were used to design in situ macromolecular chain transfer agents involved in coordinative chain transfer copolymerization (CCTcoP) of ethylene and butadiene. Olefin block copolymers were formed for the first time by the switch from anionic polymerization to CCT(co)P.