Direct laser patterning for transparent superhydrophobic glass surfaces without any chemical coatings

Abstract

This study describes a simple method to fabricate a transparent superhydrophobic soda-lime glass surface. The method uses only laser-beam machining and heat treatment, without the application of a chemical coating. The resulting surface exhibited superhydrophobicity at a contact angle (CA) greater than 170° and a sliding angle (SA) less than 10°. In addition, relatively acceptable transmittance (> 50%) in visible light was observed. The superhydrophobic surface and superior transmittance were shown at relatively high laser powers (0.4 and 0.5 W), with a relatively large step size (300 and 350 µm). At a laser power of 0.2 W, the superhydrophobicity of the surface decreased. When the step size was increased from 150 to 350 µm with a reduced laser power (0.2 and 0.3 W), the CA decreased slightly and the SA increased from 5° to 60°. CA and SA can, therefore, be controlled with process parameters.