Anomalous capillary filling and wettability reversal in nanochannels

Abstract

This work revisits capillary filling dynamics in the regime of nanometric to subnanometric channels. Using molecular dynamics simulations of water in carbon nanotubes, we show that for tube radii below one nanometer, both the filling velocity and the Jurin rise vary non-monotonically with the tube radius. Strikingly, with fixed chemical surface properties, this leads to confinement-induced reversal of the tube wettability from hydrophilic to hydrophobic for specific values of the radius. By comparing with a model liquid metal, we show that these effects are not specific to water. Using complementary data from slit channels, we then show that they can be described using the disjoin-ing pressure associated with the liquid structuring in confinement. This breakdown of the standard continuum framework is of main importance in the context of capillary effects in nanoporous media, with potential interests ranging from membrane selectivity to mechanical energy storage.

References in corpus (10)

• Nanofluidics, from bulk to interfaces
• Friction of Water on Graphene and Hexagonal Boron Nitride from ab initio Methods: Very Different Slippage Despite Very Similar Interface Structures
• Capillary Rise in Nanopores: Molecular Dynamics Evidence for the Lucas-Washburn Equation
• Optimizing water permeability through the hourglass shape of aquaporins
• Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media - topical review
• Capillary rise of water in hydrophilic nanopores
• Quantitative study of laterally inhomogeneous wetting films
• Capillary filling with giant liquid/solid slip: dynamics of water uptake by carbon nanotubes
• Large permeabilities of hourglass nanopores: From hydrodynamics to single file transport
• A microscopic view on contact angle selection

Cited by in corpus (8)

• Molecular transport through capillaries made with atomic-scale precision
• Fluids at the Nanoscale: from continuum to sub-continuum transport
• Molecular dynamics study of nanoconfined TIP4P/2005 water: how confinement and temperature affect diffusion and viscosity
• Fast water flow through graphene nanocapillaries: a continuum model approach involving the microscopic structure of confined water
• Carbon membranes for efficient water-ethanol separation
• Labyrinthine water flow across multilayer graphene-based membranes: molecular dynamics versus continuum predictions
• Communication: Truncated non-bonded potentials can yield unphysical behavior in molecular dynamics simulations of interfaces
• Coupled imbibition and evaporation of droplets deposited on a nanoporous layer