Resolving mechanical properties and healing performance trade-off via TiO2/CuS heterojunction nanoparticles for sunlight-driven self-healing polyurethane

The simultaneous integration of high strength, toughness, and self-healing capacity in a single material has presented significant challenges. Additionally, most self-healing systems require external stimuli like artificial light or heat to activate the repair process. This study addressed these issues by incorporating TiO 2 /CuS heterojunction nanocrystals into a dynamic oxime-urethane-based polyurethane with metal-coordination interactions. The heterojunction broadened the material's light absorption to entire-spectrum sunlight, enabling the synthesized polyurethane to achieve efficient solar-driven self-healing. The resulting polyurethane exhibited a high healing efficiency of 98.6 % under sunlight, along with outstanding mechanical properties including a tensile strength of 28.43 MPa, elongation at break of 1755 %, toughness of 261.7 MJ/m 3 , and fracture energy of 246.64 kJ/m 2 . Meanwhile, the TiO 2 /CuS heterojunction also endowed the material with strong antibacterial properties, demonstrating a 99 % antibacterial rate. This work resolved the inherent conflict between mechanical performance and self-healing efficiency through the synergistic design of heterojunction nanocrystals and dynamic bonds. It provided a new strategy for developing high-strength, tough materials with effective sunlight-responsive self-healing capabilities. The resulting material holds great potential for applications in smart coatings, flexible electronics, wearable devices.