Transparent Self-Healing Coating with Antibacterial Properties Developed for Durable Applications

A transparent polyurethane coating that can heal scratches when heated and simultaneously kill bacteria has been developed by researchers, addressing long-standing challenges in protective surface materials. The coating maintains high clarity comparable to bare glass and retains its properties after seawater immersion and recycling, suggesting practical applications for devices exposed to daily wear and microbial contamination.

Polyurethane coatings are widely used on cars, ships, electronics, and public surfaces, but they typically degrade through scratching, fouling, and bacterial attachment, which clouds transparency and weakens the material. Previous self-healing films often relied on single-use microcapsules or sacrificed transparency or antibacterial capability. The new coating, detailed in a study published in Chinese Journal of Polymer Science on October 11, 2025, overcomes these limitations by incorporating dynamic selenonium salts into the polymer network.

A research team from Jiangsu University of Technology, Soochow University, and Ghent University engineered the material using a one-pot synthesis and thermal curing strategy. This approach gives the coating vitrimer-like reprocessability, allowing polymer chains to rearrange under heat while remaining robust at room temperature. When scratched, the coating heals visibly within one hour at 140°C, and with slight pressure, recovery time shortens to approximately 20 minutes. Even after multiple cut-and-remold cycles, the films preserve their chemical structure and mechanical behavior.

Antibacterial testing showed that selenonium-containing samples dramatically inhibited the growth of E. coli and S. aureus bacteria, with high-loading formulations nearly eliminating colonies. Scanning electron microscopy images revealed ruptured bacterial membranes, indicating a contact-killing mechanism that doesn't rely on leaching chemicals. Optical measurements confirmed 90–91% light transmittance, comparable to bare glass, and the coating remained clear after two weeks of simulated seawater immersion with minimal swelling. The material achieved a pencil hardness of 1H and adhesion ratings of 4B–5B, meeting standards for protective coatings on devices and marine windows.

The technology could benefit phone screens, touch panels, underwater lenses, public facilities, medical devices, and ship equipment where scratches and microbial contamination present daily challenges. Its high clarity means it can coat optical components without image loss, while its 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, potentially extending product durability and reducing waste in multiple industries. The research was financially supported by multiple organizations including the National Natural Science Foundation of China and the European Research Council under the European Union's Horizon 2020 Research and Innovation Program.