Strong and crack-tolerant elastomers via geometrically confined H-bonding semicarbazides.

The development of high-performance elastomers that are simultaneously strong, crack-tolerant, and wear-resistant remains a persistent challenge. Herein, we design bio-inspired semicarbazide chain extender featuring high-density hydrogen-bonding sites to synthesize poly(urethane-urea) (PUU). The use of two such extenders creates geometric confinement that promotes ordered H-bonding arrays, which synergistically enhances the mechanical performance. The resulting PUU-HI elastomer exhibits a nanoscale-ordered phase-separated structure and maximized H-bonding, achieving a tensile strength of 120.2 MPa, toughness of 400.5 MJ m-3 and true fracture stress of 1.3 GPa, even surpassing spider silk. The architecture additionally delivers high crack tolerance, fatigue resistance, and high wear resistance, making it ideal for stable, long-term used triboelectric nanogenerator interfaces. Solid-state NMR reveals the geometric-confinement-induced ordered and high-density H-bonding structure in hard domain for efficient energy dissipation. By designing tailored H-bonding motifs and amplifying supramolecular interactions via geometric confinement, this work offers a promising strategy for developing mechanically robust and durable elastomers.