Structuration et nanorhéologie d’un liquide confiné : étude par AFM dynamique.

Abstract

In this paper, we present two types of experimental results. Firstly presented are very good results recently obtained within our group (Nanophysics on soft material and biological systems-CPMOH-Université Bordeaux 1) at the end of a study carried out on octamethylcyclotetrasiloxane (C8H26Si4O3) confined between a plane solid graphite surface and the tip of a commercial Atomic Force Microscope (AFM), used in dynamic mode tapping. Secondly more recent results of a study undertaken on the confinement of salted water, by the same technique, on the mica plane surface are analysed. We show that when the AFM tip approaches the surface, the variation of the amplitude and of the delay of phase of the detected signal, according to the tipsurface distance, present oscillations. The measurement of the period of these oscillations provides a value equal to the diameter of the molecule of the confined liquid.

Key words: Confined liquid, AFM probes, tapping-Mode AFM, oscillatory dissipation, effective viscosity.