OTES modified transparent dip coated silica coatings

• Published in: Ceramics international Vol. 39; no. 1; pp. 835 - 840
• Main Authors: Parale, V.G., Mahadik, D.B., Mahadik, S.A., Kavale, M.S., Wagh, P.B., Gupta, Satish C., Rao, A. Venkateswara
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2013
• Subjects: Coatings; Contact angle; Dip coating; Hydrophobicity; Methyl alcohol; Oxalic acid; Roughness; Silica coatings; Silica glass; Silicon dioxide; Transparent; Ultrahydrophobic; Dip coating; Transparent; Silica coatings; Ultrahydrophobic
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2012.05.079

The present paper describes the room temperature synthesis of dip coated water repellent silica coatings on glass substrates using octyltriethoxysilane (OTES) as a co-precursor with two-step sol–gel process. Silica sol was prepared by keeping the molar ratio of tetraethylortosilicate (TEOS) precursor, methanol (MeOH) solvent, acidic water (0.001M oxalic acid) and basic water (12M NH4OH) constant at 1:11.03:0.17:0.58 respectively, throughout the experiments and the OTES weight percentage was varied from 0% to 15%. It was found that with an increase in wt% of OTES, the roughness and hydrophobicity of the films increased, however the optical transmission decreased from 93% to 88% in the visible range. The hydrophobic silica films retained their hydrophobicity up to a temperature of 259°C and above this temperature, the films became hydrophilic. The hydrophobic silica thin films were characterized by taking into consideration the surface roughness studies, Fourier transform infrared (FT-IR) spectroscopy, percentage of optical transmission, scanning electron microscopy (SEM), Thermogravimetric-differential thermal analysis (TG-DTA) and contact angle measurements.