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 (BLMR). These BLMR monomers underwent robust and well‐controlled ring‐opening polymerization to afford P(BLMR) products with high thermal stability, enhanced water resistance, and tunable mechanical properties. Impressively, chemical recycling of P(BLMR) 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 semi‐aromatic 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.