A transparent polyurethane coating that repairs scratches when heated and prevents bacterial growth has been developed by researchers from Jiangsu University of Technology, Soochow University, and Ghent University. The material, detailed in a study published on October 11, 2025, in Chinese Journal of Polymer Science, maintains clarity comparable to bare glass and functions after seawater immersion and recycling, addressing long-standing challenges in protective coatings.
Polyurethane coatings are widely used on cars, ships, electronics, and public surfaces, but they often degrade due to scratches, fouling, and microbial attachment. Existing self-healing materials typically rely on single-use microcapsules or sacrifice transparency or antibacterial properties. The new coating, engineered with dynamic selenonium salts, overcomes these limitations by enabling polymer chains to rearrange under heat, providing vitrimer-like reprocessability while remaining robust at room temperature.
In tests, the coating healed scratches within 1 hour at 140°C, with recovery time reduced to approximately 20 minutes under slight pressure. Even after multiple cut-and-remold cycles, the films preserved their chemical structure and mechanical behavior. Antibacterial assessments showed that selenonium-containing samples significantly inhibited E. coli and S. aureus growth, with high-loading versions nearly eliminating bacterial colonies. Scanning electron microscopy images revealed ruptured bacterial membranes, indicating a contact-killing mechanism.
The coating demonstrated approximately 90–91% light transmittance, matching bare glass, and maintained transparency after two weeks of simulated seawater immersion with minimal swelling. Its pencil hardness reached 1H, and adhesion was rated 4B–5B, meeting standards for protective applications on devices and marine windows. The research, accessible via https://doi.org/10.1007/s10118-025-3414-7, highlights the material's potential for sustainable design due to its recyclability.
This technology could benefit phone screens, touch panels, underwater lenses, public facilities, medical devices, and ship equipment, where scratches and microbial contamination pose daily challenges. Its high clarity allows for use on optical components without image loss, while its recyclability supports circular material economies. With further scale-up and long-term weathering tests, the coating may reduce maintenance costs and biofouling in marine or healthcare environments, paving the way for next-generation coatings that remain clean, clear, and repairable throughout their lifespan.
