Three-Phase Fluid Coexistence in Heterogenous Slits.

0523937 - ÚCHP 2021 RIV US eng J - Journal Article
Láska, Martin - Parry, A.O. - Malijevský, Alexandr
Three-Phase Fluid Coexistence in Heterogenous Slits.
Physical Review Letters. Roč. 124, č. 11 (2020), č. článku 115701. ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA ČR GA17-25100S
Institutional support: RVO:67985858
Keywords : liquid bridges * phase-behaviour * transition
OECD category: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)
Impact factor: 9.161, year: 2020
Method of publishing: Limited access

We study the competition between local (bridging) and global condensation of fluid in a chemically heterogeneous capillary slit made from two parallel adjacent walls each patterned with a single stripe. Using a mesoscopic modified Kelvin equation, which determines the shape of the menisci pinned at the stripe edges in the bridge phase, we determine the conditions under which the local bridging transition precedes capillary condensation as the pressure (or chemical potential) is increased. Provided the contact angle of the stripe is less than that of the outer wall we show that triple points, where evaporated, locally condensed, and globally condensed states all coexist arc possible depending on the value of the aspect ratio a = L/H, where H is the stripe width and L the wall separation. In particular, for a capillary made from completely dry walls patterned with completely wet stripes the condition for the triple point occurs when the aspect ratio takes its maximum possible value 8/pi. These predictions are tested using a fully microscopic classical density functional theory and shown to be remarkably accurate even for molecularly narrow slits. The qualitative differences with local and global condensation in heterogeneous cylindrical pores are also highlighted.
Permanent Link: http://hdl.handle.net/11104/0308230