Depolymerization of End-of-Life Poly(lactide) via 4-Dimethylaminopyridine-Catalyzed Methanolysis

The chemical recycling of end-of-life plastics/polymers can contribute to a more sustainable society. In this regard, the selective degradation (depolymerization process) leading to well-defined low molecular weight chemicals is a key feature of the chemical recycling. Based on that, we have investigated the depolymerization of end-of-life poly(lactide)-based (PLA) goods. In more detail, applying a combination of methanol and catalytic amounts of 4-dimethylaminopyridine (DMAP) end-of-life PLA was depolymerized to methyl lactate, a chemical which can be is used as green solvent or as starting material for new poly(lactide) products. With the assistance of microwave heating an excellent rate of depolymerization (>99%) was observed within short reaction times (10-20 min). Interestingly, a set of 16 PLA commodities was efficiently transformed to methyl lactate.