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

Abstract

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 {(Me 2 Si(C 13 H 8 ) 2 )Nd(μ-BH 4 )[(μ-BH 4 )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-cobutadiene) (EBR) produced by CCT(co)P were combined and the corresponding structures were characterized.

Presenting the shape of sound through a dual-mode strain/tactile sensor

“…Olen block copolymers contain crystallizable ethylene-octene chain segments (hard segments) with low comonomer content and high melting temperature, and amorphous ethylene-octene chain segments (so segments) with high comonomer content and low glass transition temperature. [33][34][35] Compared to random copolymers, the hard segments give the copolymer a fairly high crystallization and melting temperature, and a more regular crystallization morphology, while maintaining a low glass transition temperature. Generally, OBCs have high elasticity, good wearing resistance, and excellent mechanical performance.…”

Ethylene‐Coordinative Chain‐Transfer Polymerization‐Induced Self‐Assembly (CCTPISA)

“…The underpinning self‐assembly mechanism leading to this morphology cannot be fully elucidated at this stage although self‐assembly does occur during polymerization and upon the growth of the polyethylene segments as shown by the turbidity observed and in agreement with a polymerization‐induced self‐assembly (PISA) mechanism. This PISA system is mediated by catalytic coordination–insertion polymerization and opens the way to the design of original block copolymers and organic nanoparticles based on polyolefins, including by the use of original polymerization switch such as from anionic to CCTP [61] …”

Coordinative Chain Transfer and Chain Shuttling Polymerization

“…113 The reverse switch, from anionic polymerization to CCTP mechanism, was also reported. 114 The targeted Mg-polymeryls were synthesized with a narrow molar mass distribution (Đ = 1.06) and used without any purification as macroCTAs for CCTP catalyzed by the ansa-bis(fluorenyl) complex [Me 2 Si-(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)] 2 (30, Figure 9) (Scheme 49).…”