Resisting and pinning of a nanodrop by trenches on a hysteresis-free surface

Cheng Chung Chang, Cyuan Jhang Wu, Yu Jane Sheng, Heng Kwong Tsao

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Abstract

The encounter of a nanodrop with a trench on a hysteresis-free surface is explored by many-body dissipative particle dynamics to show the effect of surface roughness on droplet wetting. A free nanodrop exhibits Brownian motion and the diffusivity decays exponentially with the liquid-solid contact area. In contrast, as the nanodrop sits on a trench, its random motion is constrained. Work must be done to overcome the energy barriers for the transition between free and trapped states. The potential energy landscape is thus constructed based on the force-displacement plot. It is shown that the trench acts as a hydrophobic blemish for capture but like a hydrophilic blemish for escape. A drop always breaks up after detachment from a hydrophilic trench. Therefore, the drop tends to bypass a small trench when it meets one. The macroscopic experiments are performed by fabricating liquid-infused surfaces with extremely low contact angle hysteresis. The experimental observations agree qualitatively with simulation outcomes.

Original languageEnglish
Article number164702
JournalJournal of Chemical Physics
Volume145
Issue number16
DOIs
StatePublished - 28 Oct 2016

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