Sacrificial H-Bond Arrays Reinforce Dynamic Covalent Networks for Ultra-tough, Solvent-Resistant, and Self-healable Polyurethanes

Abstract

Reconciling high toughness and solvent resistance with dynamic adaptability under mild conditions remains challenging for self-healable polymer networks. Here, we report a dual-dynamic polyurethane elastomer (PCL-ADH-FBR) in which an acylurea-derived, high-density hydrogen-bonding array is integrated with a dynamic boronic ester network. FTIR analysis indicates that 84.6% of the C=O groups participate in hydrogen bonding. The resulting elastomer reaches a fracture energy of 307 kJ/m2, a toughness of 477 MJ/m3, and a tensile strength of 61.2 MPa. In situ synchrotron X-ray scattering reveals sequential energy dissipation through hydrogen-bond disruption and strain-induced crystallization of the PCL segments. The dense hydrogen-bond network also restricts solvent ingress. The material retains more than 85% of its tensile strength after 7 days in water and recovers more than 90% of its tensile properties after 12 h exposure to 12 tested solvents followed by drying at 60 °C for 24 h. After healing at 90 °C for 24 h, the sample recovers 98.5% of its tensile strength and 99.4% of its elongation at break, and the material can be repeatedly reprocessed. A flexible triboelectric nanogenerator fabricated from PCL-ADH-FBR delivers an open-circuit voltage of 54.4 V and recovers 97% of its output after damage and healing. These results support a physically reinforced dynamic-network strategy for combining mechanical robustness, environmental stability, and functional recoverability in polyurethane elastomers.