Achieving
ultrafast resilience comparable to that of irreversible
cross-linking elastomers remains a formidable challenge for self-healing
supramolecular elastomers. Herein, we construct a π-type tweezer
structure formed by imidazolidinylurea and aromatic imine to stabilize
dynamical hard domains (SDHDs) in polyurethane (PU) elastomers. SDHDs
endow the dynamic PU network with high binding energy and minimal
stress relaxation at room temperature, similar to irreversible covalent
cross-links. As such, the elastomer demonstrates rapid resilience
comparable to vulcanized natural rubber as well as high mechanical
strength and toughness. Meanwhile, SDHDs can be readily activated
upon heating, enabling exceptional healing ability (∼100% healing
efficiency) under mild conditions (50 °C) and complete recovery
of mechanical properties after recycling. More interestingly, the
PU elastomer exhibits significant elastocaloric effects with an adiabatic
temperature change of −13.5 °C, surpassing that of state-of-the-art
vulcanized natural rubber (−9.4 °C). Therefore, this work
presents a new approach for structural design that enables a balance
between conflicting characteristics and expands the potential applications
of self-healing supramolecular elastomers.