Tuning water adhesion of superhydrophobic surface by way of facile laser–chemical hybrid process

Superhydrophobic surfaces with various water adhesion behaviours have received tremendous attention in both fundamental research and practical applications. In this work, a novel laser–chemical hybrid process was developed to fabricate superhydrophobic surface with both low and high water adhesion. Periodic cross-hatch micro-bulge arrays were fabricated on aluminum alloy surface by way of nanosecond laser irradiation. After surface chemical treatment, the laser–chemical treated surface showed either superhydrophobicity with low water adhesion using silane treatment only, or superhydrophobicity with high water adhesion using both silane treatment and sodium chloride (NaCl) treatment. The change of water adhesion on the laser–chemical treated superhydrophobic surface was attributed to the simultaneous decrease of surface energy and increase of attraction between the water droplet and sodium chloride salt. This approach could provide a novel but simple solution to tune the water adhesion of superhydrophobic metallic surfaces, thus benefiting related research and industrial areas.