Quantifying density fluctuations in water at a hydrophobic surface: evidence for critical drying

Abstract

Employing smart Monte Carlo sampling techniques within the grand canonical ensemble, we investigate the properties of water at a model hydrophobic substrate. By reducing the strength of substrate-water attraction we find that fluctuations in the local number density, quantified by a rigorous definition of the local compressibility $\chi (z)$, increase rapidly for distances $z$ within $1$ or $2$ molecular diameters from the substrate as the degree of hydrophobicity, measured by the macroscopic contact angle $\theta$, increases. Our simulations provide evidence for a continuous (critical) drying transition as the substrate-water interaction becomes very weak: $\cos (\theta )\to -1$. We speculate that the existence of such a transition might account for earlier simulation observations of strongly enhanced density fluctuations.

References in corpus (3)

• The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor like
• How water meets a very hydrophobic surface
• The Local Compressibility of Liquids near Non-Adsorbing Substrates: A Useful Measure of Solvophobicity and Hydrophobicity?

Cited by in corpus (5)

• A unified description of hydrophilic and superhydrophobic surfaces in terms of the wetting and drying transitions of liquids
• Critical Drying of Liquids
• Drying and Wetting Transitions of a Lennard-Jones Fluid: Simulations and Density Functional Theory
• Modulus-Pressure Equation for Confined Fluids
• Binding potentials for vapour nanobubbles on surfaces using density functional theory