Geometry-induced Interface Pinning at Completely Wet Walls.

0505858 - ÚCHP 2020 RIV US eng J - Journal Article
Malijevský, Alexandr
Geometry-induced Interface Pinning at Completely Wet Walls.
Physical Review E. Roč. 99, č. 4 (2019), s. 040801. ISSN 2470-0045. E-ISSN 2470-0053
R&D Projects: GA ČR GA17-25100S
Institutional support: RVO:67985858
Keywords : contact angles * adsorption * nonplanar
OECD category: Physical chemistry
Impact factor: 2.296, year: 2019
Method of publishing: Open access
https://arxiv.org/pdf/1904.13114.pdf

We study complete wetting of solid walls that are patterned by parallel nanogrooves of depth D and width L with a periodicity of 2L. The wall is formed of a material which interacts with the fluid via a long-range potential and exhibits first-order wetting transition at temperature T-w, should the wall be planar. Using a nonlocal density functional theory we show that at a fixed temperature T > T-w the process of complete wetting depends sensitively on two microscopic length scales L-c(+) and L-c(-). If the corrugation parameter L is greater than L-c(+), the process is continuous similar to complete wetting on a planar wall. For L-c(-) < L < L-c(+), the complete wetting exhibits first-order depinning transition corresponding to an abrupt unbinding of the liquid-gas interface from the wall. Finally, for L < L-c(-) the interface remains pinned at the wall even at bulk liquid-gas coexistence. This implies that nanomodification of substrate surfaces can always change their wetting character from hydrophilic into hydrophobic, in direct contrast to the macroscopic Wenzel law. The resulting surface phase diagram reveals a close analogy between the depinning and prewetting transitions including the nature of their critical points.
Permanent Link: http://hdl.handle.net/11104/0297224