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

Abstract 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(SiMe 3 ) 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.