Catalytic improvement of titanium complexes bearing bis(aminophenolate) in ring-opening polymerization of L-lactide and ε-caprolactone

This study synthesized and examined a series of titanium aminophenoxide complexes as catalysts for the ring-opening polymerization of L-lactide and epsilon-caprolactone. These Ti complexes are more active for LA than for CL. The interaction between coordinating atoms of the ligands and the central metal ions has a considerable influence on the resulting catalyses. The complex with thiophenyl groups demonstrated the highest catalytic activity, due to the lability of thiophenyl groups. Rapid changes between association and dissociation can be used to tune the electronic density of Ti in order to avoid contending with the coordination of L-lactide and epsilon-caprolactone to increase activity. In addition, kinetic results indicate a first-order dependency on [(LTi)-Ti-OMe((OPr)-Pr-i)(2)] and a first-order dependency on [CL] and [LA] respectively. (C) 2014 Elsevier B.V. All rights reserved.