0497925 - ÚCHP 2019 RIV US eng J - Journal Article
Malijevský, Alexandr - Parry, A.O.
Modified Kelvin Equations for Capillary Condensation in Narrow and Wide Grooves.
Physical Review Letters. Roč. 120, č. 13 (2018), č. článku 135701. ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA ČR GA17-25100S
Grant - others:EPSRC(GB) EP/L020564/1
Institutional support: RVO:67985858
Keywords : capillary condensation * phase transitions * density functional theory
OECD category: Physical chemistry
Impact factor: 9.227, year: 2018 ; AIS: 3.203, rok: 2018
DOI: https://doi.org/10.1103/PhysRevLett.120.135701

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 theta = 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 theta(E) describing the shape of the meniscus formed at the top of the groove. The dependence of theta(E) 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 theta < 45 degrees 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 theta* approximate to 31 degrees. 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.
Permanent Link: http://hdl.handle.net/11104/0290385