Ring-closing depolymerization of polyglycolide to glycolide through a synergistic transesterification strategy

The chemical recycling of plastics to monomers provides efficient assistance for sustainable development of plastics. For polyglycolide (PGA), it has gained widespread attention to be a highly promising plastic material due to its excellent performance. However, research on the ring-closing depolymerization of PGA has yet to break through. The depolymerization is mainly limited by the challenges brought by high crystallinity and melting point of PGA, and instability of glycolide (GL). In this work, a synergistic transesterification strategy is proposed to achieve efficient depolymerization of PGA to monomer GL. Utilizing the versatile catalyst zinc bis[bis(trimethylsilyl)amide] (Zn(HMDS)2) to promote simultaneous intramolecular and intermolecular transesterification, the random chain scission and back-biting depolymerization is achieved in succession. Therefore, the depolymerization product GL can be obtained in high yield and purity. This strategy will provide new research ideas for the chemical recycling of plastics.