Preparation of Fluorine‐Free and Superhydrophobic SiO2 Film with High Transmittance

Abstract Superhydrophobic film has broad application prospect in daily life. Herein, superhydrophobic SiO 2 film was prepared with chemical modification reducing the film's surface energy and sol mixing increasing its surface roughness. Tetraethoxysilane (TEOS) was used as precursor, trimethylethoxysilane (TMES) was used as modifier. Both the modified SiO 2 film and the mixed SiO 2 film were obtained with dip‐coating. With the increase of TMES addition, the characteristic peak intensity of hydrophilic hydroxyl group in Fourier transform infrared spectrum (FTIR) decreased, and that of the hydrophobic methyl group increased; the modified SiO 2 film surface was relatively smooth and its root‐mean‐square (RMS) roughness ranged 1.86‐5.41 nm, while that of the mixed SiO 2 film increased from 11.20 nm to 42.60 nm; the contact angle of the modified SiO 2 film increased from 19.08° to 127.37°, while that of the mixed SiO 2 film increased from 129.47° to 158.47°; the average transmittance of the modified SiO 2 film first decreased from 94.86 % to 94.14 % and then increased to 94.43 %, while that of the mixed SiO 2 film decreased gradually from 96.99 % to 94.84 %. Finally, the fluorine‐free superhydrophobic SiO 2 film with the average contact angle of 158.47° and the average transmittance of 94.84 % was obtained.