Design of selective divalent chain transfer agents for coordinative chain transfer polymerization of ethylene and its copolymerization with butadiene

Abstract

PhMg(CH2)5MgPh and MesMg(CH2)5MgMes – divalent bis-metalated chain transfer agents (CTA) – were designed, synthesized and implemented in the polymerization of ethylene or the copolymerization of ethylene with butadiene mediated by...

Structure–Reactivity Relationship of Organozinc and Organozincate Reagents: Key Elements towards Molecular Understanding

“…The data collected suggests the formation of monomeric species. This contrasts with the chemistry of organomagnesium reagents in which dimer structures have been reported as stable intermediates along the Schlenk equilibrium [26a,29] …”

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

“…Mesitylmagnesium bromide (MesMgBr) was used for transmetallation reactions performed in this study. The choice of this Grignard reagent is based on our previous studies that showed that the Nd complex does not initiate polymer chain when combined with mesitylmagnesium compounds [36] . If transmetallation performed after an anionic polymerization is successful, this feature would allow to resume the polymerization of ethylene or the copolymerization of ethylene and butadiene exclusively from the polymer formed during the anionic step to achieve clean block copolymers as shown in Scheme 1.…”

Coordinative Chain Transfer and Chain Shuttling Polymerization

“…47 The design and use of bis metalated chain transfer agents (Va-b, Figure 8) for ethene CCTP and ethene/1,3-butadiene CCTcoP with the neodymocene borohydride complex [Me 2 Si(C 13 H 8 ) 2 Nd(BH 4 ) 2 Li(THF)] 2 (30, Figure 9) was reported. 48 Based on DFT calculations, a divalent MesMg-(CH 2 ) 5 MgMes CTA (Vb, Figure 8) was designed to enable the selective initiation of the polymerization on the alkyl side, together with strong evidence of ethene CCTP and ethene/ 1,3-butadiene CCTcoP. This original feature is ascribed to a formation of the mesityl active site in the trimetallic bridged complex with the neodymium that is thermodynamically not favored due to the dissociation of the complex.…”

“…These interesting features allow additionally the synthesis of homotelechelic polyethylene in a one-step procedure, with very good functionalization efficiencies (87−91%, Table 3). 48 The CCTP concept was also adopted for the synthesis of long-chain branched polyolefins using original Dow's Hf pyridylamido complex (3, Figure 2) activated with tetrakis-(pentafluorophenyl)borate salt [(C 18 H 37 ) 2 MeNH][B(C 6 F 5 ) 4 ] and various dialkylzincs, carrying vinyl groups (VIa-c, Figure 8), as CTA and comonomer at the same time. 49 Long-chain branches were formed during ethene/propene and ethene/1- octene copolymerization (Scheme 12), while the best CTA/ comonomer for this purpose was (9-decenyl) 2 Zn (VIa, Figure 8).…”