Controlled Trans-stereospecific Polymerisation of Isoprene with Neodymium (III) Borohydride-dialkylmagnesium system

Michael Terrier (1) , Marc Visseaux (1) , Thomas Chenal (1) , André Mortreux (1)

1 UCCS - Unité de Catalyse et Chimie du Solide - UMR 8181

Neodymium trisborohydride, associated with MgR2 alkylating agents, affords an efficient initiator for the stereospecific polymerization of isoprene. This system presents good activity (150 kg of polyisoprene/mol of Nd/h; 95% yield in 2 h) and is trans-stereospecific (up to 97.7%), and its polymerization shows a quasi-living character. The molecular weights are controlled by the [Isoprene]/[Nd] ratio, with a polydispersity index lower than 1.6. A full study is presented here, including the influence of the nature of the alkylating reagent (MgR2), the solvent, the reaction temperature, the [MgR2]/[Nd] ratio, and the replacement of neodymium by other lanthanides. This work also includes a kinetic study of the system and a detailed NMR study of the microstructure of the trans-polyisoprene obtained, providing mechanistic insights about the polymerization reaction.

Mots clés: catalysis; dialkylmagnesium; isoprene; living polymerization; kinetics (polym.); metal-organic catalysts/organometallic catalysts; neodymium borohydride; NMR; polymerization; stereospecific polymers; trans-polyisoprene

Domaines: Catalyse; Polymères

Michael Terrier, Marc Visseaux, Thomas Chenal, André Mortreux. Controlled Trans-stereospecific Polymerisation of Isoprene with Neodymium (III) Borohydride-dialkylmagnesium system. Journal of Polymer Science Part A: Polymer Chemistry, 2007, 45, pp.2400. ⟨10.1002/pola.22002⟩. ⟨hal-00265642⟩