A new transparent polyurethane coating that can heal scratches under moderate heat while preventing 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, addresses longstanding challenges in protective coatings by combining transparency, self-healing capability, antibacterial properties, and recyclability in a single formulation.
Traditional polyurethane coatings protect surfaces on cars, ships, electronics, and public touchpoints but are vulnerable to scratches, fouling, and microbial attachment that gradually cloud transparency and weaken structural integrity. Many existing self-healing materials rely on microcapsules that function only once or sacrifice transparency or antibacterial capability. The new coating overcomes these limitations through dynamic selenonium salts embedded in the polyurethane network, enabling polymer chains to rearrange under heat for repair while maintaining robustness at room temperature.
According to the research published at https://doi.org/10.1007/s10118-025-3414-7, the coating demonstrated rapid healing capabilities. When scratched, samples healed visibly within one hour at 140°C, with recovery time shortening to approximately 20 minutes with slight pressure. Even after multiple cut-and-remold cycles, the films preserved their chemical structure and mechanical behavior, indicating significant recyclability.
The antibacterial performance proved equally impressive. Selenonium-containing samples dramatically inhibited growth of E. coli and S. aureus bacteria, with high-loading formulations nearly eliminating bacterial colonies. Scanning electron microscope images revealed ruptured bacterial membranes, suggesting a contact-killing mechanism rather than chemical leaching. This characteristic makes the coating particularly valuable for medical settings and marine environments where bacterial resistance without chemical release is urgently needed.
Optical measurements confirmed the coating maintains approximately 90-91% light transmittance, comparable to bare glass, with clarity preserved even after two weeks of simulated seawater immersion and minimal swelling. Mechanical testing showed pencil hardness reaching 1H and adhesion rated 4B-5B, meeting standards for protective coatings on electronic devices and marine windows.
"This coating behaves like a living surface—it can recover from damage and defend itself against bacteria," the authors explained. "The key lies in the dynamic selenonium chemistry, which allows the polymer network to reorganize during healing while keeping the surface hostile to microbes." The material's ability to maintain transparency and mechanical stability after repeated recycling demonstrates promise for sustainable material design.
The technology has broad potential applications including phone screens, touch panels, underwater lenses, public facilities, medical devices, and ship equipment where scratches and microbial contamination present daily challenges. Its high clarity allows coating of optical components without image distortion, while recyclability supports circular material economies. With further development including scale-up, long-term weathering tests, and flexibility adjustments, the coating could significantly reduce maintenance costs and biofouling in marine and healthcare environments.
This advancement represents a significant step toward next-generation coatings that maintain cleanliness, clarity, and repairability throughout their lifespan, potentially transforming how protective surfaces are designed for demanding applications across multiple industries.
