Critical Drying of Liquids

TL;DR

This study uses simulations and density functional theory to analyze the critical drying transition of liquids at substrates, revealing new insights into fluctuation phenomena and critical behavior near interfaces.

Contribution

It provides a detailed analysis of the critical drying transition using realistic models, highlighting discrepancies with theoretical predictions and elucidating fluctuation effects.

Findings

Critical drying occurs at zero substrate attraction for long-range potentials.

The critical exponent for parallel correlation length is over twice the predicted value.

Fluctuation phenomena are significant near hydrophobic and solvophobic interfaces.

Abstract

We report a detailed simulation and classical density functional theory study of the drying transition in a realistic model fluid at a smooth substrate. This transition (in which the contact angle $\theta\to 180^\circ$) is shown to be critical for both short ranged and long-ranged substrate-fluid interaction potentials. In the latter case critical drying occurs at exactly zero attractive substrate strength. This observation permits the accurate elucidation of the character of the transition via a finite-size scaling analysis of the density probability function. We find that the critical exponent $\nu_\parallel$ that controls the parallel correlation length, i.e. the extent of vapor bubbles at the wall, is over twice as large as predicted by mean field and renormalization group calculations. We suggest a reason for the discrepancy. Our findings shed new light on fluctuation phenomena in fluids near hydrophobic and solvophobic interfaces.