Transparent composite-structure antifogging coating with mechanical abrasion resistance and environmental durability

Superhydrophilic SiO2 coatings offer unparalleled advantages in terms of antifogging properties. However, they show suboptimal mechanical abrasion resistance and environmental durability, limiting their application. Accordingly, research has focused on the trade-off between hydrophilicity and mechanical abrasion resistance as well as between environmental durability and visible transmittance in superhydrophilic SiO2 coatings. Herein, a composite-structure coating with a densely distributed particulate phase and enhanced crosslinking strength is developed without the use of organic compounds. The coating exhibits remarkable transparency and antifogging properties, with an average transmittance similar to that of bare glass and a water contact angle of approximately 0 degrees. Moreover, the coating exhibits impressive hardness and adhesion of up to 4H and 5B, respectively. The coating retained its antifogging properties even after undergoing 500 cycles of wear induced using a 3000-mesh sandpaper, impact of sand (40 g) dropped from a height of 40 cm, 10 weeks of exposure to the outdoor environment, and 25 h of immersion in water. The test results demonstrate that the coating exhibits satisfactory mechanical abrasion resistance and environmental durability, which are essential for its practical applications. The composite structure formed using linear SiO2 molecules as crosslinking agents with spherical SiO2 nanoparticles considerably enhances the adhesion and abrasion resistance of the coatings. Overall, the developed composite-structure coatings will facilitate their commercial viability and expand the application of superhydrophilic materials in various research fields.