A transparent polyurethane coating that heals scratches when heated and simultaneously prevents bacterial growth has been developed by researchers, addressing long-standing challenges in protective materials for electronics, marine equipment, and public surfaces. The coating maintains clarity comparable to bare glass and functions even after seawater immersion or recycling, representing a significant advancement toward durable, multifunctional protective films.
Polyurethane coatings are widely used on cars, ships, electronics, and public-touch surfaces, but they gradually degrade from scratches, fouling, and microbial attachment. Previous self-healing materials often relied on single-use microcapsules or sacrificed transparency or antibacterial capability. Marine environments and medical settings particularly need coatings that resist bacteria without leaching chemicals. Creating a single material that is transparent, healable, antibacterial, and reprocessable has been difficult because improving one function typically compromises others.
A team from Jiangsu University of Technology, Soochow University, and Ghent University reported their findings on October 11, 2025, in the Chinese Journal of Polymer Science. They engineered the coating using dynamic selenonium salts embedded in a polyurethane network through a one-pot synthesis and thermal curing strategy. This chemistry allows polymer chains to rearrange under heat, giving the material vitrimer-like reprocessability 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. The material preserves its chemical structure and mechanical behavior even after multiple cut-and-remold cycles. Antibacterial tests showed that selenonium-containing samples dramatically inhibited Escherichia coli and Staphylococcus aureus growth, with high-loading formulations nearly eliminating bacterial colonies. Scanning electron microscope images revealed ruptured bacterial membranes, indicating a contact-killing mechanism.
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. Pencil hardness reached 1H, and adhesion was rated 4B–5B, meeting standards for protective coatings on devices and marine windows. The researchers noted that the coating maintains performance after seawater soaking and recycling, pointing to a practical solution for surfaces facing daily wear.
"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 allows coating of 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.
