Surface wetting of liquid nanodroplets: Droplet-size effects

The spreading of liquid nanodroplets of different initial radii R0 is studied using molecular dynamics simulation. Results for two distinct systems, Pb on Cu(111), which is nonwetting, and a coarse-grained polymer model, which wets the surface, are presented for Pb droplets ranging in size from ∼55000 to 220000 atoms and polymer droplets ranging in size from ∼200000 to 780000 monomers. In both cases, a precursor foot precedes the spreading of the main droplet. This precursor foot spreads as rf2(t)=2Defft with an effective diffusion constant that exhibits a droplet-size dependence Deff∼R01/2. The radius of the main droplet rb(t)∼R04/5 is in agreement with kinetic models for the cylindrical geometry studied. © 2005 The American Physical Society.