Impact-resistant, high-toughness, self-healable elastomers with physical-chemical dual-crosslinking networks for efficient energy absorption

The intense mechanical impact that causes serious hazards has made stringent requirements for protective materials. Supramolecular elastomers integrating high toughness, impact resistance, and self-healing properties are desired as intelligent energy-absorbing materials. Herein, we construct a physical-chemical dual-network polyurethane (PU), via the dissociation and reconfiguration of dynamic hierarchical hydrogen bonds enables energy dissipation and self-healing properties, and the chemical cross-linking network maintains the stability and recoverability of the elastomer network. By tuning the proportion of the physical-chemical network in the elastomer, the supramolecular PU elastomer not only exhibits extraordinary ductility (1922.71 %), and excellent toughness (22.10 MJ m −3 ), but also shows outstanding impact resistance (an energy absorption efficiency of 85.6 %). The dissociation of dynamic hierarchical hydrogen bonds under high frequency renders the elastomer with special strain-hardening properties, which allows the material to absorb tremendous impact energy. The presence of a covalent crosslinking network prevents the creeping of the PU molecules and assists in the recovery and reconstruction of hydrogen bonds, as well as the self-healing of the material. In addition, the supramolecular PU demonstrates remarkable capability to enhance the energy absorption performance of commercial thermoplastic PU foam. By incorporating 30 % of supramolecular PU, the composite foam prepared by supercritical CO 2 foaming exhibits an outstanding energy absorption efficiency of 85.1 %, owing to the buffering property of the porous structure and the strain-hardening effect of the supramolecular PU. The physical-chemical dual-network elastomer provides a potential strategy for intelligent anti-impact materials and foams.