Synergistic Supramolecular Bonding Enables Self‐Reinforcing and Chemically Recyclable Sustainable Materials

Developing polymer materials that break the long‐standing trade‐off between long‐term durability and efficient chemical recyclability remains a fundamental challenge. We report an environmentally self‐reinforcing and easily recyclable unprecedented biomass‐derived supramolecular polyester that circumvents this limitation through the synergistic integration of dynamic hydrogen bonds and halogen‐bond‐assisted depolymerization. Amide‐mediated hydrogen‐bond networks undergo environment‐activated supramolecular rearrangement under hygrothermal, ultraviolet, and electrical aging conditions, promoting chain realignment, recrystallization, and network densification. As a result, the material exhibits self‐reinforcing behavior, achieving an ultrahigh tensile strength of 138.4 MPa (61% increase) and a UV‐shielding efficiency of 98% (36% increase) while maintaining excellent electrical insulation. Simultaneously, halogen‐bond interactions enhance solvent penetration and facilitate ester activation, enabling rapid depolymerization in dichloromethane at ambient temperature. Monomers are recovered with >99% purity and >90% yield for closed‐loop repolymerization, while also enabling molecular upcycling into supramolecular adhesives exhibiting exceptional chemical resistance and an ultrahigh cryogenic bonding strength of 11.0 MPa at −196°C. This work establishes a supramolecular design principle that decouples service‐life reinforcement from end‐of‐life chemical deconstruction, providing a general strategy for reconciling durability and recyclability in polymeric materials.