Ultrafast ring-opening copolymerization of lactide with glycolide toward random poly(lactic-co-glycolic acid) copolymers by an organophosphazene base and urea binary catalysts

Abstract

The preparation of poly(lactic-co-glycolic acid) (PLGA) copolymers with controllable random microstructures remains as a challenge due to the much higher reactivity of glycolide (GA) compared to lactide (LA). In this contribution, we present the one-pot ring-opening copolymerization (ROCOP) of LA with GA to produce random PLGA copolymers with tunable monomer sequence lengths using an organophosphazene base/urea binary catalyst. Ultrafast copolymerizations with high monomer conversions (>95%) were achieved at ambient temperature within a few seconds. A series of PLGA copolymers with molar masses ranging from 4.6 to 13.0 kDa were obtained by changing monomer feeding ratios. The microstructures of the obtained PLGA copolymers can be tuned by changing the feeding molar ratio of LA/GA, and were carefully characterized using ¹³C NMR spectroscopy. The thermal properties of PLGA copolymers were also explored, and they exhibited composition dependent behaviors.