Facile fabrication and antifogging test of a calcination-free SiO 2 superhydrophilic coating

The low cost, accessibility, and ease of implementation of SiO 2 hydrophilic coatings should encourage further promotion as practical surface treatments. The calcination process, however, poses an obstacle to convenience. Herein, a calcination-free, antifogging SiO 2 superhydrophilic coating was prepared at room temperature by sol–gel method with the guidance of particle gradation theory, which was used to regulate the size and concentration of colloid nanoparticles. The surface micromorphology, roughness, and water contact angle (WCA) of coatings were characterized and measured using scanning electron microscope (SEM), atomic force microscope (AFM), and contact angle measuring equipment. The antifogging capability of superhydrophilic coating was also examined. It has been found that hydrophilicity of coatings can be significantly improved by reasonable particle gradation design. The closer the particle packing pattern is to the hexagonal close-packing model, the better the hydrophilicity of coatings. When the concentration ratio of particle diameter 60.29, 9.26, and 3.68 nm is 15:4:1, the coating exhibits exceptional hydrophilicity (WCA, 2.3°) and outstanding anti-fogging performance. An implication of this study is that a versatile and easily manipulated strategy is presented here for designing surface microstructures that are sensitive to roughness. Graphical Abstract