Force of Adhesion upon loss of Contact Angle Hysteresis: when a Liquid behaves like a Solid

Liquids and solids are in general expected to behave very differently in their contact with a solid surface. While that the mechanical deformation of an elastic solid sphere is perfectly reversible, a liquid drop normally deforms in an irreversible way. Nevertheless, a liquid drop in contact with a perfectly-solvophobic surface should also deform reversibly, giving rise to loss of contact angle hysteresis. In this work,\footnote{Escobar J.V. and Castillo R., Phys. Rev. Lett., 111, 22, 226102, (2013)} the theoretically predicted vanishment of the macroscopic contact angle hysteresis is found experimentally along with a small but finite force of adhesion 0.55 $\mu$N that, unexpectedly, is independent of the history of the preload. These results are obtained with a novel Capillary Force Microscope. Our results agree with the prediction of a model in which the surface tension of the liquid provides the counterpart of the restoring force of an elastic solid, evidencing that the dewetting of a liquid in the absence of strong pinning points is equivalent to the detachment of an elastic solid.