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Séminaire 14.11.2013 à 15h

par Benjamin Rotenberg - 25 octobre 2013

Kerstin Falk, du Department of Civil and Environmental Engineering du MIT (Cambridge, MA, Etats-Unis), présentera un séminaire le 14 novembre 2013 à 15h00 dans la bibliothèque du laboratoire PECSA (7e étage, bâtiment F, porte 754) intitulé :

The role of structure and confinement in nanofluidics - simulation and theory of fluid transport in carbon nanopores


Fluid properties at the nanoscale follow unforeseen principles. For example, biological nanofluidic channels, filters, etc... (for example aquaporines) or lubricant systems (made of self-assembling lipid structures) outperform predictions based on hydrodynamics (HD) theory by several orders of magnitude. Experiments with new nanofluidic devices made of nanotubes revealed similarly large scale-ups for fluid transport [1,2]. To quantify these phenomena, a better understanding of fluid properties at the smallest scales is essential.

I will present molecular simulations studies of different nanofluidic systems, focused on the question whether classical macroscopic descriptions hold, or have to be extended to account for confinement and surface effects. In particular, I discuss the influence of pore size, pore shape and wall structure on the permeability of nanoporous membranes. To this end, we consider various carbon materials : highly ordered, atomically smooth structures (graphene, carbon nanotubes) as well as isotropic disordered materials (amorphous porous carbons).

Channels with atomistically smooth walls feature ultra-fast liquid transport. This is due to exceptionally large slippage at the liquid-solid interface. Furthermore, the slip also depends on the structure properties of both the wall and the liquid. I will show how these effects can be understood based on theoretical considerations for the liquid-solid friction coefficient [3,4]. Fluid flow through amorphous materials is more challenging to assess theoretically because of the irregular pore shapes. While we expect that roughness on the pore walls impedes substantial slip in this case, confinement effects might still lead to large deviations from the macroscopic prediction for the flow rate, given by Darcy’s law.

Références :

[1] Holt et al., Science 312, 1034 (2006)

[2] Siria et al., Nature 494, 455–458 (2013)

[3] Falk et al., Nano Letters 10, 4067 (2010)

[4] Falk et al., Langmuir 28, 14261 (2012)

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