Synergistic Pathways in PLA Breakdown and PTMC Formation: A One-Pot Eutectic-Driven Recycling Mechanism

This study introduces a novel one-pot strategy for the chemical valorization of poly(lactic acid) (PLA), coupling its base-catalyzed depolymerization with the ring-opening polymerization (ROP) of trimethylene carbonate (TMC). The process exploits an eutectic mixture of lactide (LA) and TMC, which lowers the thermal input required for PLA degradation. Using potassium aryloxide (KOAr^tBu) as a bifunctional catalyst, the PLA is first quickly hydrolyzed into oligomers or lactic acid, which subsequently initiate the slower polymerization of TMC. Notably, this transformation operates in the presence of residual water, eliminating the need for tedious drying steps. The method achieves selective PLA breakdown conversion and produces (oligo)lactic acid end-capped poly(trimethylene carbonate) (PTMC) with tunable molar mass, depending on water content.