Upcycling of Mechanically Robust and Self-Healing Polyurethane Elastomers via Reinforcing and Catalytic Effects of Boron Coordination

The high-performance design, damage-responsive healability, and economy-driven upcycling establish an unprecedented prospect for sustainable polyurethane (PU) utilization across the material lifecycle. However, combining upcycling, high performance, and self-healing properties in a single polymer material remains a significant challenge. Herein, we construct boron–nitrogen (B–N) coordination interactions in polyurethane containing oxime-carbamate bonds. The strategic incorporation of B–N coordination enables a valid integration of network reinforcement and dynamic bond activation (two seemingly antagonistic mechanisms) within PU matrices, manifesting extraordinary reinforcing and catalytic effects. It reinforces the dynamic network by forming additional coordination bonds, more hydrogen bonds, and more pronounced microphase separation, thereby significantly improving the mechanical properties, the fracture stress increasing from 20.6 to 40.7 MPa and the toughness from 38.8 to 69.9 MJ/m3. Furthermore, the B–N coordination accelerates the exchange of oxime-carbamate bonds at room temperature and promotes their dissociation at elevated temperatures. This accelerated exchange process doubles the room-temperature self-healing efficiency of the PU. Moreover, the catalytic dissociation generates more isocyanate (−NCO) groups at high temperatures, which not only enable the upcycling of waste PU into a strong universal adhesive but also facilitate the formation of an upcycled polyurea network with improved mechanical properties. Overall, the dual reinforcing and catalytic effects of B–N coordination provide a promising approach for achieving PU upcycling with exceptional mechanical properties and an improved lifetime.