Electrowetting-based control of wetting transition of a nanodroplet on pillar-arrayed surfaces
Journal
Journal of Molecular Liquids
Journal Volume
345
Date Issued
2022
Author(s)
Abstract
Two extreme wetting states, a highly non-wetting Cassie state and a wetting Wenzel state, can coexist or even mutually convert on patterned surfaces. Such a conversion process may be spontaneous or induced by external stimuli. This work studies the wetting transition of a nanodroplet on pillar-arrayed surfaces induced by an external electric field via an energy-minimization method in conjunction with molecular dynamics (MD) simulations. The simulation results reveal that driven by the electric field, the initial Cassie state could go through a partial wetting state, and eventually converts to the Wenzel state. The free-energy landscape reveals that there are multiple local energy minima, corresponding to multiple metastable states. For the metastable Cassie state, the wetting transition is irreversible, i.e., the droplet would remain in the Wenzel state when the electric field is removed. Conversely, the spontaneous dewetting transition from the Wenzel to the Cassie state can occur, if only the Cassie droplet is in a global energy minimum configuration. Thus, the stable Cassie wetting configuration is essential for triggering the spontaneous dewetting transition. ? 2021 Elsevier B.V.
Subjects
Dewetting transition
Electrowetting transition
Surface energy
Textured surfaces
Wetting state
Drops
Electric fields
Free energy
Interfacial energy
Molecular dynamics
Textures
Cassie state
Electrowetting
Energy
Nano-droplets
Textured surface
Wenzel state
Wetting transitions
Wetting
Type
journal article