Chemically Robust Anti-Fog Nanocoating Through Multilayer Deposition of Silica Composite Nanofilms

A coating must remain intact to perform its inherent functions on a surface, and often functional organic coatings fail due to deterioration because of their intrinsic vulnerabilities. In this work, we present a biomimetic material based on a glass sponge to provide a robust silica composite nanocoating with an anti-fog effect. The silica composite nanocoating was constructed with a binary film structure consisting of (1) a Fe(III)-tannic acid (TA) nanofilm for adhesion to coat the substrates and (2) a SiO₂ layer to enhance the durability of the coating. Due to the universal coating property of Fe(III)-TA nanofilms, we demonstrated that the silica composite nanocoating was effective regardless of the substrate. By Layer-by-Layer (LbL) assembly of the silica composite, it is possible to precisely control the nanocoating thickness. The superhydrophilic nature of the SiO₂ layer showed an exceptional anti-fog effect that remained intact against multiple deteriorative conditions, including acid treatment, peroxide degradation, sudden temperature change, severe heat conduction, and oil contamination. In addition, the silica composite nanocoating is scalable for surfaces of different shapes and sizes with the aid of a spray-assisted deposition technique. The bio-inspired, multi-composite nanocoating strategy herein contributes to the improvement of organic coatings for uses in applications to tackle current technological problems.