Generalization of Kelvin's equation for compressible liquids in nanoconfinement

The Kelvin equation for a compressible liquid in nanoconfinement is written in a form that takes into account not only Laplace's pressure, but also the oscillatory compression pressure. This leads to a simple analytical equation for pressure in nanocapillaries. The corrected equation is used to analyze properties of aqueous systems, including the oscillatory structural forces between attractive surfaces and inert surfaces, repulsive “hydration” forces between hydrophilic surfaces, and attractive “hydrophobic” forces between hydrophobic surfaces. Relative vapor pressure in a nanocapillary also is discussed.

Graphical abstractAnalytical extension to the Kelvin equation is derived to predict oscillations around classical behavior in nanocapillary. The pressure predicted by proposed model for n  -hexadecane in coordinates of ln(p/pS)ln(p/pS) vs 1/r1/r qualitative agree with direct measurements.Figure optionsDownload full-size imageDownload as PowerPoint slide