The Cassie-to-Wenzel wetting transition of water films on textured surfaces with different topologies

The Cassie–Wenzel (C–W) wetting transition has been extensively investigated; however, the wetting transition of water films on textured surfaces with different topologies, together with underlining mechanisms, is unsatisfactorily explored. In this study, the C–W wetting transition of water films on pillar-arrayed and striped surfaces is studied. The results show that, on pillar-arrayed surfaces, the free energy variation during the C–W wetting transition follows the classical wetting pathway. The free energy first increases with the intrusion of water into the asperities and then decreases after a water film touches the basal surface. However, on striped surfaces, there exist multiple partial wetting states with each one occupying a local energy-minimization configuration. Accordingly, the water film needs to overcome multiple energy barriers to realize the C–W wetting transition. Moreover, the effects of aspect ratio and intrinsic wettability of the two textured surfaces on the C–W wetting transition are discussed.