Development of maintenance-free coatings using composite titania and silica

Abstract

Atmospheric conditions and the effect of pollutants on the frequently exposed glass furnishings like windows in constructions and windshield in automotive industries often require maintenance due to their extensive usage and heavy exposure. This demanded an additional coating on the conventional glass furnishings to free from the pollutants without additional cleaning cost. Hydrophilicity and hydrophobicity are properties of titania (TiO2) and silica (SiO2) dielectric materials, although when coated as a composite material, they exhibit a larger affinity for water than carbon contamination. Hence, the contamination adsorbed on the surface of the glass can be easily cleaned by water without help of any detergent or cleaning agents. In this work, we report the fabrication and analysis of three TiO2-SiO2 composite coatings (single coated 1C, double coated 2C and triple coated 3C) on glass substrates using the sol-gel spin coating technique. The coatings were subjected to X-ray diffraction (XRD) analysis, which revealed a broad peak at Bragg angle 25 °, confirming the existence of mixed anatase TiO2 and amorphous SiO2. Fourier transform infrared transmission spectroscopy (FT-IR) studies on the coatings demonstrated peaks at 906 cm−1 and 768 cm-1 that corresponds to the characteristic bond of Si-O-Ti, and stretching bond of Ti-O-Ti respectively. The ultraviolet visible and near-infrared spectroscopy (UV-Vis-NIR) studies on the coatings endorsed 40% reflection in the ultraviolet and near-infrared spectral regions and found increasing the composite coating can increase the reflectance further. Finally, water contact angle (WCA) analysis indicated the hydrophilic character of the coatings, with contact angles of 74.8 ° (1C), 83.3 ° (2C), and 112.7 ° (3C) and suggested as a maintenance free coating on the glass furnishings.