A new transparent polyurethane coating that can repair scratches within minutes and simultaneously kill bacteria has been developed by researchers from Jiangsu University of Technology, Soochow University, and Ghent University. The study, published in the Chinese Journal of Polymer Science, introduces a material that addresses the longstanding challenge of combining transparency, self-healing, antibacterial properties, and reprocessability in a single coating.
Polyurethane coatings are widely used to protect surfaces such as cars, ships, electronics, and public-touch points. However, they are prone to scratches, fouling, and microbial attachment, which degrade clarity and performance over time. Existing self-healing films often rely on microcapsules that provide only one-time healing, or they sacrifice transparency or antibacterial capability. The new coating overcomes these limitations by embedding dynamic selenonium salts into a polyurethane network.
Using a one-pot synthesis and thermal curing strategy, the researchers created a material where polymer chains can rearrange under heat, giving it vitrimer-like reprocessability while remaining robust at room temperature. When scratched, the coating healed visibly within one hour at 140 °C, and with slight pressure, recovery time shortened to about 20 minutes. Even after multiple cut-and-remold cycles, the films preserved 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 versions nearly eliminating colonies. Scanning electron microscopy images revealed ruptured bacterial membranes, indicating a contact-killing mechanism. Optical measurements confirmed about 90–91% light transmittance, comparable to bare glass, and the coating remained clear after two weeks of simulated seawater immersion with minimal swelling. Pencil hardness reached 1H and adhesion was rated 4B–5B, meeting 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 added 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.
This research was funded by the National Natural Science Foundation of China, the Natural Science Foundation of the Jiangsu Higher Education Institution, the China Scholarship Council, the Research Foundation Flanders, and the European Research Council under the European Union's Horizon 2020 Research and Innovation Program.
