Experimental and Numerical Study of the Role of Disorder on Contact Angle Hysteresis

Hysteretic behavior of the contact angle of a liquid on a solid is often ascribed to topographic or chemical heterogeneity of the surface. Recent experiments by Rolley and Guthmann\footnote{E. Rolley and C. Guthmann, {\it Phys. Rev. Lett.} {\bf 98}, 166105 (2007).} on liquid hydrogen on cesium suggest that both the hysteresis and the contact line dynamics might be explained in terms of the mesoscale structure of the cesium surface. We have investigated a room temperature system with similar wetting and structural properties, tetradecane on dodecanethiol-treated evaporated gold films, and compare the results with a model of the expected hysteresis due to the topographical heterogeneity as measured by AFM, and reported disorder in the thiol film.\footnote{E. Delamarche, B. Michel, H. Kang and C.Gerber, {\it Langmuir} {\bf 10}, 4103 (1994).}