Wetting and nonwetting near a tricritical point

Abstract

The dihedral contact angles between interfaces in three-fluid-phase equilibria must be continuous functions of the bulk thermodynamic fields. This general argument, which we propose, predicts a nonwetting gap in the phase diagram, challenging the common belief in "critical-point wetting", even for short-range forces. A demonstration is provided by exact solution of a mean-field two-density functional theory for three-phase equilibria near a tricritical point (TCP). Complete wetting is found in a tiny vicinity of the TCP. Away from it, nonwetting prevails and no wetting transition takes place, not even when a critical endpoint is approached. Far from the TCP, reentrant wetting may occur, with a different wetting phase. These findings shed light on hitherto unexplained experiments on ternary water-oil-nonionic amphiphile mixtures in which nonwetting continues to exist as one approaches either one of the two critical endpoints.

arXiv commentto appear in Physical Review Letters

References in corpus (3)

• A unified description of hydrophilic and superhydrophobic surfaces in terms of the wetting and drying transitions of liquids
• Three-phase equilibria in density-functional theory: interfacial tensions
• Interfacial Tensions near Critical Endpoints: Experimental Checks of EdGF Theory

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• Learning the bulk and interfacial physics of liquid-liquid phase separation with neural density functionals
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• Complete Wetting and Drying at Sinusoidal Walls
• Critical exponents of fluid-fluid interfacial tensions near a critical endpoint in a nonwetting gap