Dual catalysis: new approaches for the polymerization of lactones and polar olefins.

Recently catalytic systems combining Al, In or Zn Lewis acids with organic bases (amines, phosphines, N-heterocyclic carbenes) have been shown to efficiently promote the polymerization of lactones and polar olefins. In this frontier article, such dual approaches of polymerization catalysis are presented. Special attention is devoted to the mode of action of the dual systems and the underlying cooperative effects.