Ring‐Opening Polymerization Enables Access to High‐Performance Aliphatic‐Aromatic Polyamides with Chemical Recyclability

Although polyamides (PAs) have served as one of the most important engineering thermoplastics, it remains a long-standing challenge for chemical recycling of PAs to monomers. Herein, we report a facile approach to construct a series of benzo-fused caprolactams with various functionalities (BLM^R). These BLM^R monomers underwent robust and well-controlled ring-opening polymerization to afford P(BLM^R) products with high thermal stability, enhanced water resistance, and tunable mechanical properties. Impressively, chemical recycling of P(BLM^R) to monomer could be accomplished with excellent efficiency in dilute solution at 100-150 °C with a mixed catalyst of t-BuOK and La[N(SiMe₃)₂]₃, thus establishing a closed-loop circularity. The precise control of the polymerization and the recyclability of these semiaromatic polyamides promote a sustainable circular economy while offering the potential to access high-performance materials with tunable thermal and mechanical properties and enhanced water resistance.