2D Polyamides Enable Self-Healing and Recyclable Elastomers with High Robustness, Toughness, and Crack Resistance via Supramolecular Interactions.

High-performance elastomers with exceptional mechanical properties and self-healing capabilities have garnered significant attention due to their wide range of potential applications. However, designing elastomers that strike a balance between self-healing capabilities and mechanical properties remains a considerable challenge. Inspired by biological cartilage, a highly robust, tough, and crack-resistant self-healing elastomer is presented by incorporating hydrogen-bond-rich 2D polyamide (2DPA) into a poly(urethane-urea) matrix. This integration enhances supramolecular interactions driven by multiple hydrogen bonds. The resulting elastomer exhibits impressive strength (54.6 MPa), remarkable elongation at break (705.4%), exceptional toughness (116.7 MJ m), outstanding crack resistance (fracture energy up to 187.2 kJ m), high self-healing efficiency (98.9% at 50 °C for 9 h, 97.9% at room temperature for 48 h), and excellent recyclability, capable of lifting ≈40 000 times its own weight. Furthermore, a damage-tolerant, fatigue-resistant anticorrosive coating from this elastomer, showcasing its potential for protective skin applications in underwater robotics is developed. The underlying enhancement mechanism is validated through testing of various elastomers and molecular dynamics simulations, confirming the potential of engineering 2DPA for high-performance elastomers by leveraging supramolecular interactions.