Self-Healing Transparent Coating Repairs Scratches and Fights Bacteria

A transparent polyurethane coating that repairs scratches when heated and simultaneously prevents bacterial growth has been developed by researchers, addressing longstanding challenges in protective films for devices exposed to wear and microbial contamination. The study, published in Chinese Journal of Polymer Science on October 11, 2025, demonstrates a material that maintains clarity comparable to bare glass while offering self-healing and antibacterial properties—a combination previously difficult to achieve due to functional trade-offs.

Polyurethane coatings are widely used on cars, ships, electronics, and public surfaces, but they gradually degrade from scratches, fouling, and microbial attachment. Existing self-healing materials often rely on single-use microcapsules or sacrifice transparency, while antibacterial coatings may leach chemicals. The new coating, engineered by a team from Jiangsu University of Technology, Soochow University, and Ghent University, incorporates dynamic selenonium salts into a polyurethane network, enabling polymer chains to rearrange under heat for repair while disrupting bacterial cell membranes through contact-killing.

According to the research detailed in the journal article available at https://doi.org/10.1007/s10118-025-3414-7, the coating healed scratches within 20 minutes at 140°C with slight pressure and maintained approximately 90–91% light transmittance. Antibacterial tests showed high-loading versions nearly eliminated E. coli and S. aureus colonies, with scanning electron microscopy images confirming ruptured bacterial membranes. The material retained transparency, structure, and antibacterial function after seawater immersion and multiple recycling cycles, with pencil hardness of 1H and adhesion ratings of 4B–5B meeting protective coating standards.

The authors noted that the dynamic selenonium chemistry allows the polymer network to reorganize during healing while keeping the surface hostile to microbes, describing it as behaving like a living surface. This functionality suggests applications for phone screens, touch panels, underwater lenses, public facilities, medical devices, and ship equipment, where scratches and microbial contamination pose daily challenges. The coating's high clarity enables use on optical components without image loss, and its recyclability supports sustainable material design.

With further development including scale-up, long-term weathering tests, and flexibility adjustments, the technology could reduce maintenance costs and biofouling in marine and healthcare environments. The work represents a significant advancement toward next-generation coatings that maintain cleanliness, clarity, and repairability throughout their lifespan, potentially transforming how protective films are designed for demanding applications.