Spider silk-inspired dynamic multi-hard-domain reinforcement enables tough, puncture- and tear-resistant polycaprolactone-based polyurethanes

Elastomeric materials are essential for emerging applications including wearable electronics, soft robotics, biomedical devices, and flexible structural components. However, bio-based polyurethane elastomers often exhibit insufficient mechanical robustness. In this study, we report a spider silk-inspired dynamic multi-hard-domain reinforcement strategy to construct a hierarchical polycaprolactone (PCL)-based polyurethane elastomer. By integrating chemically heterogeneous hard domains with distinct interaction strengths, a multilevel phase-separated network is established. Structural characterization revealed the coexistence of hard-domain aggregates and localized PCL crystalline domains, which cooperatively act as dynamic physical crosslinks that engage under deformation. This architecture enables strain-adaptive stress transfer and hierarchical energy dissipation. The resulting PIPU elastomer exhibits a tensile strength of 21.4 MPa, an ultrahigh elongation at break of 1143 %, and a fracture energy of 121.6 kJ m −2 , excellent puncture resistance and pronounced strain-adaptive mechanical behavior. These results demonstrate a versatile multi-hard-domain strategy for engineering high-performance polyurethane elastomers.