Nanoscale Investigation of Wetting Dynamics with a Surface Force Apparatus

We study the dynamic properties of a fluid interface of nanometric curvature formed by capillary condensation between solid substrates. The interaction force between the substrates is measured with a surface force apparatus, and gives access to the line force acting on the three-phase contact line. We focus on a situation where this line force is dominated by wetting hysteresis. At the submicronic scale, hysteresis does not behave as at the macroscopic scale. We show that it can be described by a ``recovery length,'' and interpret the results in terms of the jog length of the contact line.