A pinch of silver salt to enable rac-lactide ring-opening polymerisation at room temperature using Ti-salen complexes

Abstract

Exploiting non-covalent interactions (NCIs) has become a powerful tool in catalyst design, including those for polymer reactions. Herein we report a simple strategy relying on the addition of silver salt to Ti-salen complexes, leading to Ti/Ag cooperativity via cation-Π interactions. Three different Ti-salen complexes were investigated alongside several silver salts. In all cases, these Ti/Ag systems led to good or high activity at room temperature for rac-lactide ROP, a rare feature for Ti-based catalysts. Interestingly, the weakly coordinating anion (WCA) of the silver salt was found not only to affect activity but also stereocontrol in the polymerisation. Heterotactic PLA with Pr up to 0.7 was obtained