Non-fluorinated superhydrophobic TiO2-based coatings by suspension flame spraying

The use of nanoparticles in suspension thermal spraying allows a creation of nanostructured coatings with cauliflower-like features, which are beneficial for developing superhydrophobic surfaces. Conventional methods for producing superhydrophobic titanium dioxide (TiO₂) coatings typically involve functionalization with fluorinated groups, which are often toxic and environmentally harmful. This study presents an alternative approach to produce superhydrophobic coatings using more environmentally friendly coating production steps. This was done by functionalizing TiO₂ nanoparticles with stearic acid and combining them with liquid polymers in an alkaline solvent and alcohol to create a suspension feedstock for a flame spray process. The resulting suspension flame sprayed coatings achieved a high contact angle (CA) of approximately 160° with a low contact angle hysteresis (CAH) and a sliding angle (SA) below 5° without requiring any post-treatments, acting as the one-step coating production method. Additionally, these coatings maintained their superhydrophobic properties under various environmental conditions, offering long-term stability for outdoor applications.