Facilely-fabricated smart hydroxyl-surfaces with rapidly switchable wettability for water and oil: Reversibility between superoleophilicity and near superoleophobicity

Smart surfaces with switchable wettability for both aqueous and non-aqueous drops have aroused much interest because of their potential applications. In this work, a facile approach for the creation of tunable surface wettability on hydroxyl surfaces with rapid switch at ambient temperature is developed. Both surface hydrophobicity and oleophobicity are enhanced after a fluoro-surfactant solution rinse which acts as a stimulus. The reversal of surface wettability can be achieved simply by a rinse of aqueous solution of hexadecyltrimethylammonium bromide. This rapid wettability-switching property may be attributed to surface modification by physisorbed monolayer of fluoro-surfactant. When adopting a simple but effective pretreatment associated with surface roughening and oxidation, an extreme wettability change (between superhydrophilicity and superhydrophobicity) for both water and hexadecane drops can be achieved. This novel route is found to be durable and can be applied to a variety of surface materials including metal, ceramics, and polymer.