Transparent superhydrophobic coating with self-cleaning, anti-bacterial, and substrate compatibility properties

Superhydrophobic materials exhibit unique non-wetting and low surface energy properties, rendering them promising for diverse applications. However, their hierarchical micro/nanostructures induce pronounced light scattering, which drastically compromises optical transparency. Consequently, the development of highly transparent superhydrophobic materials remains a critical challenge in this field. In this study, we developed a transparent superhydrophobic coating using waterborne polyurethane (WPU) and fluorosilane-modified silicon dioxide (F-SiO 2 ) nanoparticles. The coating exhibits a water contact angle (WCA) of 155.9 ± 0.2° and a sliding angle (SA) of 0.9 ± 0.2°. Beyond its superhydrophobicity, more importantly, the coating demonstrates exceptionally high optical transparency, with light transmittance only 1.2 % lower than that of the bare glass substrate. Additionally, the coating shows outstanding self-cleaning, liquid repellency, acidic/alkaline droplets resistance, water droplet impact resistance, and anti-bacterial properties. After 6 h of anti-bacterial test, the coating achieved a 100 % anti-bacterial rate against both E. coli and S. aureus . Even after 12 h exposure, the anti-bacterial rates remained as high as 98.6 ± 0.4 % and 98.3 ± 0.7 % against E. coli and S. aureus , respectively. We believe the development of such a multifunctional transparent superhydrophobic coating provides a promising protective material for applications such as underwater observation windows, offshore photovoltaics, medical equipment, food packaging, etc.