Density functional theory of long-range critical wetting

Area of Science:

• Physical Chemistry
• Materials Science
• Statistical Mechanics

Background:

• Understanding fluid adsorption at solid interfaces is crucial for predicting material properties.
• Wetting phenomena, including first-order and critical transitions, are governed by complex intermolecular forces.
• Density functional theory (DFT) provides a powerful framework for modeling these interfacial behaviors.

Purpose of the Study:

• To investigate the wetting properties of fluids adsorbed on solid substrates using DFT.
• To analyze the role of fluid-fluid and substrate-fluid interactions in determining wetting transitions.
• To assess the validity of asymptotic expansions for interface potentials and the influence of long-range forces.

Main Methods:

• Employing density functional theory to model fluid adsorption.
• Performing explicit calculations of substrate-liquid and substrate-gas density profiles.
• Evaluating interface potentials via asymptotic expansion and numerical constrained minimization.

Main Results:

• Identified first-order and critical wetting transitions based on interaction parameters.
• Observed a preceding first-order transition to a mesoscopic film before critical wetting for specific parameters.
• Demonstrated that alkane behavior on brine is not universal and requires fine-tuning of interactions.
• Confirmed that long-range forces in studied models cannot be treated perturbatively.

Conclusions:

• Wetting transitions are sensitive to the interplay of short- and long-range forces.
• Perturbative treatment of long-range forces is inadequate for certain fluid-substrate systems.
• The non-universality of wetting behavior necessitates system-specific parameterization.