Capillarity Phenomena in Nanoporous Media

Capillarity in nanoporous media arises from the interplay of surface forces, pore geometry and fluid properties at the nanoscale. Confinement within pores of a few nanometres leads to enhanced surface-to-volume ratios, imprinting unique transport behaviours that depart from classical continuum predictions. Spontaneous imbibition, governed by the balance between capillary pressure and viscous resistance, controls the rate at which liquids invade a porous matrix. In addition to bulk meniscus propagation, atomically thin precursor films can spread ahead of the main front, modifying effective contact angles and accelerating or retarding imbibition. Thermodynamic considerations such as the Kelvin equation dictate phase transitions and condensation thresholds within nanopores, while hydrodynamic slip and surface-induced layering influence flow resistance. Hysteresis in adsorption–desorption loops encapsulates the combined effect of pore-size distribution, connectivity and surface chemistry. Capillarity phenomena underpin applications ranging from energy storage to drug delivery and water purification, demanding a nuanced understanding of interfacial physics, pore network topology and multi-scale modelling for rational design and optimisation.

Research from Nature Portfolio

Recent studies have introduced a hybrid nanochannel platform enabling direct measurement of liquid transport through single silica nanochannels as narrow as 7 nm. Precise capillary flow experiments revealed a progressive increase in hydraulic resistance with decreasing channel height, reaching nearly 45 % above classical hydrodynamics predictions in the smallest conduits. This departure was attributed to the formation of an immobile hydration layer of sub-nanometre thickness on the hydrophilic walls. By eliminating external pressure sensors and theoretical flow estimations, the approach provides a robust framework to quantify capillary-driven transport in both hydrophilic and hydrophobic nanofluidic systems, establishing new benchmarks for nanoscale flow characterisation.

Capillarity Phenomena in Nanoporous Media publication trend

The graph below shows the total number of articles in capillarity phenomena in nanoporous media across all publications each year (not limited to Nature Index journals).

Technical terms

Capillary pressure: Pressure difference across a curved liquid–air interface caused by surface tension and pore geometry.

Laplace pressure: Pressure jump proportional to surface tension and the reciprocal of the meniscus radius.

Precursor film: Nanometre-thick liquid layer advancing ahead of the bulk meniscus on pore walls.

Kelvin equation: Thermodynamic relation linking vapour pressure to curvature-induced capillary condensation in pores.

Imbibition: Spontaneous uptake of a wetting liquid into a porous medium driven by capillary forces.

References

1. Accurate measurement of liquid transport through nanoscale conduits. Scientific Reports (2016).
2. Diffusionlike Drying of a Nanoporous Solid as Revealed by Magnetic Resonance Imaging. Physical Review Applied (2022).
3. Polymeric liquids in mesoporous photonic structures: From precursor film spreading to imbibition dynamics at the nanoscale. The Journal of Chemical Physics (2024).