A nanofluidic exchanger for harvesting saline gradient energy.

The energy of saline gradients is a very promising source of non-intermittent renewable energy, the exploitation of which is hampered by the lack of viable technology. The most investigated harvesting methods rely on selective transport of ions or water molecules through semi-permeable or ion-selective membranes, which demonstrate limited power densities of the order of a few W m. While in the last decade, single nanofluidic objects such as nanopores of nanotubes have opened up very promising prospects with power density capabilities in the order of kW or even MW m, scale-up efforts face serious issues, as concentration polarization phenomena result in a massive loss of performance.

A dynamical calo-porosimeter to characterize wetting and drying processes in lyophobic nanometric pores.

Lyophobic heterogeneous systems, based on porous fluids made of ordered nanoporous particles immersed in a non-wetting liquid, constitute systems of interest for exploring wetting, drying, and coupled transport phenomena in nanometric confinement. To date, most experimental studies on the forced filling and spontaneous emptying of lyophobic nanometric pores, at pressures of several tens of MPa, have been conducted in a quasi-static regime. However, some studies have shown that dynamical measurements are essential to shed light on the rich physics of these phenomena.

Bowtie-Shaped Deformation Isotherm of Superhydrophobic Cylindrical Mesopores.

Deformation of superhydrophobic cylindrical mesopores is studied during a cycle of forced water filling and spontaneous drying by in situ small-angle neutron scattering. A high-pressure setup is put forward to characterize the deformation of ordered mesoporous silanized silica up to 80 MPa. Strain isotherms of individual pores are deduced from the shift of the Bragg spectrum associated with the deformation of the hexagonal pore lattice.

Dynamics of heterogeneous wetting in periodic hybrid nanopores.

We present experimental and theoretical results concerning the forced filling and spontaneous drying of hydrophobic cylindrical mesopores in the dynamical regime. Pores are structured with organic/inorganic moieties responsible for a periodicity of the surface energy along their axis. We find that the forced intrusion of water in these hydrophobic pores presents a slow dynamics: the intrusion pressure decreases as the logarithm of the intrusion time.

State and Rate Dependent Contact Line Dynamics over an Aging Soft Surface.

We report direct atomic-force-microscope measurements of capillary force hysteresis (CFH) of a circular contact line (CL) formed on a long glass fiber, which is coated with a thin layer of soft polymer film and intersects a water-air interface. The measured CFH shows a distinct overshoot for the depinning of a static CL, and the overshoot amplitude grows logarithmically with both the hold time τ and fiber speed V. A unified model based on the slow growth of a wetting ridge and force-assisted barrier crossing is developed to explain the observed time (or state) and speed (or rate) dependent CL depinning dynamics over an aging soft surface.