Ring-opening polymerization of cyclic esters initiated by lithium aggregate containing bis(phenolate) and enolate mixed ligands

A novel lithium aggregate complex [(mu(2)-/mu(3)-EDBP)(2)(OCHCH2)Li-5(THF)(4)] (1) has been synthesized by the reaction of 2,2'-ethylidenebis(4,6-di-tert-butyl-phenol) (EDBP-H-2) with 2.5 eq (BuLi)-Bu-n in tetrahydrofuran with high yield. The structure of complex 1 is determined by H-1-NMR and X-ray crystallography. Complex 1 can initiate the living ring-opening polymerization of epsilon-caprolactone and L-lactide yielding polymers with narrow molecular weight distributions, and moreover to prepare the PCL-b-PLA block copolymer. (c) 2013 Elsevier B.V. All rights reserved.