Control of wettability transition and coalescence dynamics of droplets on the surface via mechanical vibration: A molecular simulation exploration.

Graphical abstract Wetting transition and controllable coalescence dynamics can be achieved by subjecting the substrate to vibrating. Highlights • Vibration-induced wetting transition is investigated. • Well-wetting, weak-wetting and dewetting states can be switched. • A theoretical model to interpret wetting transition is established. • Vibration-induced wettability transition can control the coalescence. Abstract Controllable wettability of liquids has always been attached great significance to a wide range of applications in both industrial and technological processes. Here, we report a simple and novel approach to achieve reversible and switchable wettability through the vibration of substrate. Results showed that with the increase of the vibration frequency (f), the wetting state of the liquid metal gradually transform into wetting/dewetting mixed state, and finally becomes complete dewetting state. More importantly, on the basis of our established model (involving vibration amplitude, liquid-substrate interaction), we further interpret and predict the wetting status and the wetting transition procedure of the given droplet. Additionally, the vibration-induced wettability transition can be applied to control the coalescence dynamics, which generates three patterns: free-coalescence, semifree-coalescence, restricted-coalescence. Our work would develop a new strategy to control the surface wettability by vibrating the substrate, without any mechanical or chemical modifications, which could provide guidance in the manipulation of drop dynamics. [ABSTRACT FROM AUTHOR]