Modified Kelvin equations for condensation in narrow and wide grooves

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Title: Modified Kelvin equations for condensation in narrow and wide grooves
Authors: Parry, AO
Malijevsky, A
Item Type: Journal Article
Abstract: We consider the location and order of capillary condensation transitions occurring in deep grooves of width L and depth D. For walls that are completely wet by liquid (contact angle θ=0) the transition is continuous and its location is not sensitive to the depth of the groove. However, for walls that are partially wet by liquid, where the transition is first order, we show that the pressure at which it occurs is determined by a modified Kelvin equation characterized by an edge contact angle θE describing the shape of the meniscus formed at the top of the groove. The dependence of θE on the groove depth D relies, in turn, on whether corner menisci are formed at the bottom of the groove in the low density gaslike phase. While for macroscopically wide grooves these are always present when θ<45° we argue that their formation is inhibited in narrow grooves. This has a number of implications including that the local pinning of the meniscus and location of the condensation transition is different depending on whether the contact angle is greater or less than a universal value θ∗≈31°. Our arguments are supported by detailed microscopic density functional theory calculations that show that the modified Kelvin equation remains highly accurate even when L and D are of the order of tens of molecular diameters.
Issue Date: 27-Mar-2018
Date of Acceptance: 19-Mar-2018
DOI: 10.1103/PhysRevLett.120.135701
ISSN: 0031-9007
Publisher: American Physical Society
Journal / Book Title: Physical Review Letters
Volume: 120
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/L020564/1
Keywords: Science & Technology
Physical Sciences
Physics, Multidisciplinary
02 Physical Sciences
General Physics
Publication Status: Published
Article Number: 135701
Appears in Collections:Mathematics
Applied Mathematics and Mathematical Physics
Faculty of Natural Sciences

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