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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Interfacial and wetting properties of a binary point Yukawa fluid
Paul Hopkins1, Andrew J Archer, Robert Evans
1H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom. paul.hopkins@bristol.ac.uk
The Journal of Chemical Physics
|December 10, 2008
Summary
This study explores binary fluid mixtures near a wall, revealing complete wetting behavior with thick films forming under specific conditions. Film thickness depends logarithmically on concentration and correlates with bulk fluid properties.
Area of Science:
- Physical Chemistry
- Soft Matter Physics
- Interfacial Science
Background:
- Understanding interfacial phase behavior is crucial for designing materials and processes.
- Binary fluid mixtures exhibit complex behaviors, including phase separation and adsorption at interfaces.
- Yukawa particle models offer a simplified yet effective approach to studying fluid interactions.
Purpose of the Study:
- To investigate the interfacial phase behavior of a binary fluid mixture of repulsive Yukawa particles near a planar wall.
- To determine the conditions leading to complete wetting and analyze the characteristics of the adsorbed film.
- To map the phase transitions, including prewetting phenomena, in the system.
Main Methods:
- Utilized a simple approximation for the Helmholtz free energy functional, leading to the random phase approximation for direct correlation functions.
- Calculated equilibrium fluid density profiles using Euler-Lagrange equations, simplified via transformation into an ordinary differential equation.
- Employed quadrature for obtaining density profiles and analyzed phase separation and wetting phenomena.
Main Results:
- Observed complete wetting on the species 2-poor side of the binodal, characterized by a thick film of species 2-rich fluid adsorbed at the wall.
- Found that wetting film thickness grows logarithmically with concentration difference and is proportional to the bulk correlation length.
- Identified a line of first-order prewetting surface phase transitions separating thin and thick adsorbed films, dependent on wall-fluid interactions.
Conclusions:
- The study demonstrates complete wetting in repulsive binary Yukawa fluid mixtures under specific conditions.
- Wetting film properties are quantitatively linked to bulk fluid properties and system parameters.
- Prewetting transitions play a significant role in the interfacial phase diagram, influenced by wall-fluid interactions.
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