Critical behaviour of the contact angle within nonwetting gaps
File(s)
Published version
Author(s)
Parry, Andrew
Malijejsky, Alexandr
Rascon, Carlos
Type
Journal Article
Abstract
Recent density functional theory and simulation studies of fluid adsorption near planar walls in systems where the wall–fluid and fluid–fluid interactions have different ranges, have shown that critical point wetting may not occur and instead nonwetting gaps appear in the surface phase
diagram, separating lines of wetting and drying transitions, that extend up to the critical temperature Tc. Here we clarify the features of the surface phase diagrams that are common, regardless of the range and balance of the forces, showing, in particular, that the lines of temperature driven wetting and drying transitions, as well as lines of constant contact angle π > θ > 0, always converge to an ordinary surface phase transition at Tc. When nonwetting gaps
appear the contact angle either vanishes or tends to π as t ≡ (Tc − T)/Tc → 0. More specifically, when the wall–fluid interaction is long-ranged (dispersion-like) and the fluid–fluid short-ranged we estimate π − θ ∝ t0.16, compared with θ ∝ t0.77 when the wall–fluid interaction is short-ranged and the fluid–fluid dispersion-like, allowing for the effects of bulk critical fluctuations. The universal convergence of the lines of constant contact angle implies that critical point filling always occurs for fluids adsorbed in wedges.
diagram, separating lines of wetting and drying transitions, that extend up to the critical temperature Tc. Here we clarify the features of the surface phase diagrams that are common, regardless of the range and balance of the forces, showing, in particular, that the lines of temperature driven wetting and drying transitions, as well as lines of constant contact angle π > θ > 0, always converge to an ordinary surface phase transition at Tc. When nonwetting gaps
appear the contact angle either vanishes or tends to π as t ≡ (Tc − T)/Tc → 0. More specifically, when the wall–fluid interaction is long-ranged (dispersion-like) and the fluid–fluid short-ranged we estimate π − θ ∝ t0.16, compared with θ ∝ t0.77 when the wall–fluid interaction is short-ranged and the fluid–fluid dispersion-like, allowing for the effects of bulk critical fluctuations. The universal convergence of the lines of constant contact angle implies that critical point filling always occurs for fluids adsorbed in wedges.
Date Issued
2024-01-31
Date Acceptance
2024-01-19
Citation
Journal of Physics: Condensed Matter, 2024, 36
ISSN
0953-8984
Publisher
IOP Publishing
Journal / Book Title
Journal of Physics: Condensed Matter
Volume
36
Copyright Statement
© 2024 The Author(s). Published by IOP Publishing Ltd. Original Content from this work may be used under the
terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
License URL
Publication Status
Published
Article Number
17LT01