Accelerating effect of crown ethers on the lactide polymerization catalysed by potassium acetate

Abstract

Recent advances in catalysis enriched the toolbox to prepare well-defined polyester materials such as polylactide (PLA). Herein, we report the use of crown ethers to speed up the polymerization of L-lactide (L-LA) initiated by an exogenous alcohol and catalyzed by potassium acetate (KOAc). With KOAc, the crown ethers played a crucial role as a complexing agent, with 18-crown-6 enabling the fastest polymerization kinetics outpacing the one obtained with the pristine catalyst by not less than 73. Experimental results suggested that the 18-c-6 crown ether complexed the KOAc ion pair to in situ produce free ions, which was much more appropriate to activate the propagating alcohol for the ring-opening reaction of L-LA.