Chain Flexibility as a Fundamental Descriptor for Mild Depolymerization of Polyesters and Polycarbonates

The chemical inertness of polyesters and polycarbonates hinders their sustainable recycling under mild conditions. While solvent-assisted depolymerization shows promise, its mechanism remains poorly understood, particularly regarding the macromolecular structure. This study identifies chain flexibility as a critical factor in enabling mild depolymerization, as it facilitates solvent-mediated disentanglement and conformational mobilization. We demonstrate this principle through model systems: amorphous bisphenol-A polycarbonate (BPA-PC) and semicrystalline poly(ethylene terephthalate) (PET). Structural analyses correlate this enhancement with reduced chain rigidity and increased solvent accessibility. A dissolution−reprecipitation strategy was developed to lock polymers into high-flexibility conformations, enabling efficient catalyst-free hydrolysis under ambient conditions. The universality of this chain flexibility-driven mechanism was further validated using polylactic acid (PLA) and various postconsumer waste products. These findings establish chain flexibility as a fundamental descriptor for depolymerization, offering mechanistic insight and a practical pathway toward closed-loop plastic recycling.