Self-Healed, Tough, and Highly Resilient Elastomer Facilitated by Cooperative Hydrogen-Bonding Interaction and π–π Stacking Interaction

High-strength self-healing polyurethane elastomers offer great potential across various application fields due to their excellent combination of toughness, elasticity, and autonomous damage repair. However, achieving an optimal balance between self-healing capabilities and robust mechanical performance remains a significant challenge. In this study, we developed a composite polyurethane elastomer (PU-10% CNC) with enhanced self-healing and mechanical properties by incorporating cellulose nanocrystals (CNCs) through a solvent replacement process. This approach facilitates the uniform dispersion of CNCs within the elastomer, resulting in a composite material that leverages abundant hydrogen-bonding and π–π stacking interactions. Consequently, these supermolecular interactions collectively impart an excellent self-healing efficiency (91.8%) at room temperature. The introduction of a CNC, with its numerous hydroxyl groups, facilitates the formation of multiple hydrogen bonds, acting as reinforcing points that significantly improve the tensile strength from 3.5 to 24.6 MPa while also enhancing resilience. Moreover, the composite elastomer is fully recyclable via chemical routes, offering an environmentally friendly solution for high-performance elastomers.