Experimental investigation of the de-pinning phenomenon on rough surfaces of volatile drops

In this paper we present the preliminary results on the de-pinning phenomenon of wetting volatile drops. Wetting properties are analysed by measuring the drop base and the dynamic apparent contact angle. Three cases are investigated: reduced pressure environment, controlled substrate temperature and surfactants solutions. The experimental results are compared to the existing theories to interpret the de-pinning phenomenon. The Young unbalanced force acting through surface tension near the triple line seems to be the controlling mechanism behind the de-pinning phenomenon of evaporating drops. (c) 2005 Elsevier Ltd. All rights reserved.