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Soft nanofluidics with wetting films and soap bubbles
Anne-Laure Biance
Water and salt transports through nanoporous membranes are encountered in many applications, from desalination, filtration or energy harvesting membranes. In this talk, we will investigate the particular nature of ionic and liquid transports at the nanoscale, focusing in particular on interactions with surfaces. To get versatile liquid systems, easy to make and to tune, we use "soft matter" and we will consider here two particular systems.
The first one consists of pure water film, condensed at the surface of a hydrophilic substrate, whose thickness can be tuned continuously from one water to a few water layers. Despite this very huge confinement, our results can be accounted for by a simple continuous approach.
The second one consists of a bubble confined in a cylindrical tube filled with a surfactant solution. When the bubble is trapped, we show that this configuration can be used for filtration or desalination. But when the bubble is free, we fundamentally investigate its motion as a function of the applied electric field. Surprising bubble motion reversal and non-linearities have been observed and characterized in details.
Allemand et al., Anomalous ionic transport in tunable angstrom-size water films on silica. PNAS 2023.