A facile, low temperature spray pyrolysed tungsten oxide (WO 3 ): an approach to antifouling coating by amalgamating scratch resistant and water repellent properties

In this study, a facile spray pyrolysed hydrophobic robust tungsten oxide (WO 3 ) films were deposited at an annealing temperature of 400°C on inexpensive glass substrates, using clear and homogeneous precursor solution containing tungsten hexachloride and 2-methoxyethanol. The 10 and 15 times sprayed films were polycrystalline with the monoclinic crystal structure, uniform with the submicron-sized grain morphology (size ~320–420 nm), with an average surface roughness ranging from 12 to 17 nm and transparent above 60% in the visible region with a thickness of 380 and 550 nm, respectively. Elemental existence of tungsten and oxygen was recognized on the surface of the films possessing the highest lattice oxygen percentage of 91.1. Increment in the scratch hardness of the films with the number of sprays compared to uncoated glass was identified. The films were hydrophilic in nature (water contact angle <8°), converted to hydrophobic (>120°) by treating chemically with octadecyltrichlorosilane to form a self-assembled monolayer on the top and the hydrophobicity remained same (~120°) even after a year. These films with unique and combined properties of scratch hardness and hydrophobicity can serve in the potential application as antifouling coatings.