A team of researchers from Jiangsu University of Technology, Soochow University, and Ghent University has developed a transparent polyurethane coating that can repair scratches within minutes when heated while simultaneously killing bacteria. The coating, reported in the Chinese Journal of Polymer Science on October 11, 2025, addresses the long-standing challenge of creating a material that is simultaneously transparent, self-healing, antibacterial, and reprocessable.
Polyurethane coatings are widely used to protect cars, ships, electronics, and public surfaces, but they are prone to scratches, fouling, and microbial contamination that degrade clarity and performance over time. Many existing self-healing coatings rely on microcapsules that can only heal once, or they sacrifice transparency or lack antibacterial properties. The new coating uses dynamic selenonium salts embedded in a polyurethane network, enabling polymer chains to rearrange under heat—allowing the material to heal repeatedly—while also disrupting bacterial cell membranes on contact.
In laboratory tests, the coating, designated PU2-C7, healed visible scratches within one hour at 140°C, and with slight pressure, recovery time shortened to approximately 20 minutes. Even after multiple cycles of cutting and remolding, the films maintained their chemical structure and mechanical behavior. Antibacterial tests showed that selenonium-containing samples dramatically inhibited the growth of E. coli and S. aureus, with high-loading PU3-C7 nearly eliminating bacterial colonies. Scanning electron microscopy revealed ruptured bacterial membranes, confirming a contact-killing mechanism.
Optical measurements demonstrated that the coating maintains about 90–91% light transmittance, comparable to bare glass, and remained clear after two weeks of simulated seawater immersion with minimal swelling. The coating also achieved a pencil hardness of 1H and adhesion rated 4B–5B, meeting industry standards for protective coatings on 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." They emphasized that maintaining transparency and mechanical stability after repeated recycling demonstrates the coating's promise in durable and sustainable material design.
The technology could benefit phone screens, touch panels, underwater lenses, public facilities, medical devices, and ship equipment, where scratches and microbial contamination are daily challenges. Its high clarity means it can coat optical components without image loss, while recyclability supports circular material design. With further scale-up, long-term weathering tests, and flexibility tuning, the coating may help reduce maintenance costs and biofouling in marine or healthcare environments. The work opens the door to next-generation coatings that stay clean, clear, and repairable throughout their lifetime.
For more details, see the original study at https://doi.org/10.1007/s10118-025-3414-7.
