Plasma/thermal-driven the rapid wettability transition on a copper surface

A simple and time-saving method to realize the reversible wettability transition is reported. Through a solution–immersion process followed by stearic acid modification, a superhydrophobic surface was prepared on the copper surface. After being treated by air-plasma exposure, the surface wettability was converted into superhydrophilicity. XPS analysis demonstrated that the incorporation of oxygen species by air-plasma activation accounted for the highly hydrophilic character of the surface. Upon annealing the plasma-treated surface in air, the non-oxidized alkyl chains were transferred to the surface for recovery the superhydrophobicity. It was found that the recovery was fast upon annealing at a relative high temperature. By the alternation of air-plasma treatment and annealing process, the rapid reversible wettability transition between superhydrophobic and superhydrophilic state was realized. The shortest processing time for a whole reversible wettability transition was 21 min.