Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Poster: Wetting, Micro and nanofluidics
CPP 21.10: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Gas flow measurements in nanopores: The influence of pore wall roughness on gas dynamics — •Sebastian Kiepsch1, Simon Gruener1,3, and Patrick Huber1,2 — 1Universität des Saarlandes, Experimentalphysik, Saarbrücken, Germany — 2Pontificia Universidad Católica de Chile, Facultad de Física, Santiago, Chile — 3BASF SE, Ludwigshafen, Germany
We have measured the flow of rarefied helium gas through various nanoporous membranes within a broad temperature range (30−300 K). The materials used for these experiments (anodized aluminium oxide and Vycor glass) featured typical pore diameters in the range from 13−50 nm. The results were found to be in accordance with numerical calculations, based on a Knudsen diffusion model for cylindrical cross-sections. For Vycor glass, a tortuosity factor of τ = 3.6 ± 0.05 of the pore-network could be measured. In order to determine the influence of wall roughness on gas dynamics, the samples were reversibly modified by means of low-temperature argon vapour condensation. In this way we were able to add a monolayer of argon to the pore walls. Subsequent flow measurements with helium gave hints of higher diffusion coefficients. This effect may be related to pore wall smoothing upon argon adsorption.