Light-triggered self-renewable polyurethane materials: Wear-resistant and weather-resistant design and performance enhancement for bridge seamless expansion joints

High performance, high durability, and multifunctional synergy are the core research objectives for filler materials in bridge seamless expansion joints. This study proposes a light-triggered self-renewable strategy based on polyurethane materials, which maintains excellent mechanical properties (elongation at break > 990 %, tensile strength > 20 MPa) while achieving semi-permanent wear-resistance and weather-resistance in expansion joint materials. The core of the research lies in constructing an independent thiol-ene photoinitiated curing system: this high-photo-reactive component not only dynamically generates and renews the photocured functional surface layer during service but also significantly enhances the elongation at break of the matrix material. Experimental results show that the polyurethane material treated with the light-triggered self-renewal strategy exhibits a 63.3 % improvement in wear resistance and a 43.2 % increase in tensile fracture rate, while effectively suppressing the formation of surface micro-cracks under various aging conditions. Adhesion tests confirm that this strategy simultaneously strengthens the material’s interfacial bonding strength with multiple substrates. Dynamic shear rheometry (DSR) and Fourier-transform infrared spectroscopy (FTIR) analyses further validate that the material’s aging behavior transformation is closely related to the oxidation of sulfur-containing groups and the recombination of carbon-sulfur bonds. This study innovatively constructs a light-responsive self-renewal functional layer through an independent thiol-ene photoreaction system, providing a new technical pathway to enhance the elongation at break and long-term wear-resistance/weather-resistance of polyurethane materials for bridge seamless expansion joints.