A surface engineering: Sol-gel-based hydrophobic and superhydrophobic coating technologies

Superhydrophobic surfaces in nature provide a blueprint for designing artificial coatings with superior water repellency and self-cleaning functionality. In this study, we present a polymer-free sol–gel strategy for producing hydrophobic and superhydrophobic TiO₂-based coatings on glass substrates. Extensive experimental work was conducted to evaluate the influence of processing parameters on the resulting surface properties. Wettability was quantified through contact angle measurements, yielding tunable values from hydrophilic states to a maximum of 150°. Surface morphology and composition were examined using SEM/EDS, while crystalline phases were identified by XRD. UV–Vis analysis confirmed the optical response of the coatings, and surface roughness was measured via profilometry. FTIR and Raman spectroscopy provided detailed insights into chemical bonding and structural features. Collectively, these findings demonstrate that superhydrophobicity can be achieved entirely without the use of organic or polymeric additives, offering a durable, environmentally benign, and structurally robust alternative to conventional TiO₂/stearic acid systems.