Modulus‐Strength Decoupled High‐Toughness Elastomer for Impact Protection

Abstract Elastomers with decoupled modulus and strength are highly desirable for multi‐scenario applications, yet achieving this balance remains challenging due to inherent trade‐offs between flexibility and mechanical robustness. Here, based on polyurethane‐based elastomer, a strategy is reported that overcomes this limitation through molecualr design of hard segment combining aliphatic chain with cyclic motifs, enabling the attainment of high‐strength elastomers with tunable moduli in the range of 3–100 MPa. The optimal sample H/IP‐3.0 achieves low modulus (≈25 MPa), high tensile strength (≈76 MPa), and exceptional toughness (≈360 MJ m − 3 ). Multiscale characterization reveals that its performance stems from optimized hard‐segment stacking that balances microphase separation and dynamic hydrogen‐bond networks enabling efficient energy dissipation and strain hardening. The material demonstrates top‐tier damage tolerance, with fracture energy (515 kJ m − 2 ) and puncture resistance (1798 mJ mm −1 ). Applied to impact protection, H/IP‐3.0 attenuates blunt‐impact peak stress by ≈80% and blast‐wave overpressure by ≈69%, outperforming commercial elastomers. Mechanistic studies demonstrate that impact protection relies not solely on damping, but on optimized stress–strain response and impedance mismatch. This work provides a generalizable strategy for designing modulus‐strength‐decoupled elastomers and advanced flexible protective materials for wearable and impact mitigation applications.