Peculiar wetting behavior of nanodroplets comprising antagonistic alcohol-water mixtures on a graphene surface
Journal
Surfaces and Interfaces
Journal Volume
51
Start Page
104572
ISSN
2468-0230
Date Issued
2024-08
Author(s)
DOI
10.1016/j.surfin.2024.104572
Abstract
Binary mixtures, consisting of partially and totally wetting liquids with respect to a specific substrate and known as an antagonistic mixture, are commonly encountered. Although the wetting behavior of antagonistic mixtures deviates from that of conventional liquids, studies exploring this phenomenon are scarce. At the nanoscale, the wetting behavior of nanodroplets containing such mixtures may diverge even further from our established understanding. Employing Nanoscale Molecular Dynamics simulations, we explore the wetting behavior of nanodroplets containing mixtures of water (partial wetting) and ethanol or isopropanol (total wetting) on a graphene surface. By adjusting the water fraction (xw) in the antagonistic mixture, three distinct wetting states have been identified: (I) In total wetting regime (low xw), spontaneous spreading is observed; (II) In plateau regime (medium xw), alcohol leakage from the droplet occurs, with the apparent contact angle (CA) remaining constant; (III) In partial wetting regime (high xw), the CA increases with xw and alcohol molecules tend to accumulate at the contact line. Unexpectedly, the spreading coefficient (S) remains positive and turns negative only as xw near unity. Furthermore, Young's equation proves to be inapplicable even when S < 0. These peculiar wetting phenomena are comprehensively discussed and elucidated.
Subjects
Binary mixture
Graphene
Molecular dynamics
Nanodroplet
Wetting phenomenon
Publisher
Elsevier BV
Type
journal article