Bioinspired ultra-tough, exceptionally stretchable, and self-recoverable bio-based coating for visual damage detection and self-healing

Developing intelligent materials with integrated ultra-high-performance damage monitoring and repair functions is of paramount significance for broadening the application of the latest generation of smart materials. Here, inspired by spider silk and biological skin, we embedded multiple hydrogen bonding motifs and rigid alicyclic groups with attached damage monitoring sensors in bio-based polyurethanes to create bio-based elastomers with exceptional mechanical properties combined with repair and damage monitoring functionalities. Benefiting from the abundance of multiple hydrogen bonding elements within the polyester backbone for fracture and remodeling as external energy dissipation, and the contribution of asymmetric alicyclic groups embedded in hard domains. The elastomer possesses exceptional toughness (583 MJ·m−3) and tensile strength (43 MPa), the elongation at break point is 2600 %, and self-healing (86 % at 60 °C for 6 h), environmental adaptability, and recyclability, thereby achieving the preparation of ultra-tough self-healing elastomeric materials. Simultaneously, the internally embedded sensors enable the localization and monitoring of damage through visually observable means, such as quenching and discoloration. The elastomer recovers well in 3.5 wt% NaCl solution and provides corrosion protection (9.23 × 107 Ω·cm2 even after 50 days of immersion), achieving the integration of ultra-high mechanical performance coating materials with damage warning and repair functions. Therefore, the molecular structure design scheme of the biomimetic elastomer provides constructive guidance for surface protection application of engineering equipment in service under harsh environments.