Seminarium Fizyki Materii Skondensowanej

By taking into account precursor films accompanying nanodroplets ontrapezoidal substrates we show that on a mesoscopic level ofdescription one does not observe the phenomenon ofliquid-gas-substrate contact line pinning at substrate edges. Thisphenomenon is present in a macroscopic description and leads tonon-unique contact angles which can take values within a rangedetermined by the so-called Gibbs' criterion. Upon increasing thevolume of the nanodroplet the apparent contact angle evaluated withinthe mesoscopic approach changes continuously between two limitingvalues fulfilling Gibbs' criterion while the contact line movessmoothly across the edge of the trapezoidal substrate. The spatialextent of the range of positions of the contact line, corresponding tothe variations of the contact angle between the values given by Gibbs'criterion, is of the order of ten fluid particle diameters.