Robust superhydrophobic transparent coatings fabricated by a low-temperature sol–gel process

• Published in: Applied surface science 2014-06, Vol.305, p.702-709
• Main Authors: Huang, Wei-Heng, Lin, Chao-Sung
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Physics; Robust; Silica; Sol–gel; Superhydrophobic; Transparent
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.03.179

•The coating formed in a silica based and a fulorinated solution by dip coating.•The coating is robust, transparent, and superhydrophobic.•Superhydrophobicity is retained after ultrasonication damage and water dropping impact.•The fabrication process is feasible for scale-up production at low energy consumptions. A coating with robust, superhydrophobic, and transparent properties was fabricated on glass substrates by a sol–gel method at a temperature of 80°C. The coating was formed in a solution containing silica nanoparticles and silicic acid, in which the ratio of silica nanoparticles and silicic acid was varied to tune the roughness of the coating. Subsequently, the as-deposited coating was dipped with a low surface energy material, 1H,1H,2H,2H-perfluorooctyltrichloro silane. The coated glass substrate was characterized in terms of surface morphology, optical transmittance, water- and CH2I2-contact angles, and its chemical as well as mechanical stability was evaluated by ultrasonication in ethanol for 120min. The results showed that the coating had a water contact angle exceeding 160°, a sliding angle lower than 10°, a CH2I2 static contact angle of approximately 150°. The transmittance of the coating was reduced by less than 5% compared to that of the bare glass substrate at wavelengths above 500nm. Moreover, the properties of the coating hardly changed after the ultrasonication test and still retained the superhydrophobicity after water dropping impact. Because the fabrication process is performed under low temperatures, it is feasible for scale-up production at low energy consumptions.