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.