Elastocapillarity in nanopores: Sorption strain from the actions of surface tension and surface stress

Gennady Y. Gor, Patrick Huber, Jörg Weissmüller

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Adsorption-induced deformation of porous materials is the generation of strains in a solid due to its interaction with adsorbing fluids. The theoretical description of adsorption-induced deformation often relies on the so-called solvation pressure, the normal component of a pressure tensor in the liquid adsorbed in the pore. Recent measurements of adsorption-induced strains in two dimensions require a description that allows for the deformation to be anisotropic. Here, we present such a description. We refrain from using the solvation pressure concept and instead base the discussion on a phenomenological description of coupled mechanics and adsorption that has well-established links to continuum mechanics. We find that our approach captures all relevant features of anisotropic sorption strain; the approach thus provides a useful alternative to the solvation pressure concept. We derive analytical expressions for the stress-strain relations in a model porous material with an array of parallel channel-like pores of high aspect ratio (length/width). These relations include separate terms from the liquid pressure, from the surface stress at the liquid-solid interface, and from a spreading tension at the solid-liquid-vapor triple line. Surface stress and liquid pressure contribute to the strains along and normal to the pore axis in a qualitatively different manner. The underlying discussion of capillary forces sheds light on the variation of the surface stress during adsorption and capillary condensation.

Original languageEnglish (US)
Article number086002
JournalPhysical Review Materials
Volume2
Issue number8
DOIs
StatePublished - Aug 31 2018

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physics and Astronomy (miscellaneous)

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