Surface Wetting of Liquid Nanodroplets

Abstract

The spreading of liquid nanodroplets of different initial radii $R_0$ is studied using molecular dynamics simulation. Results for two distinct systems, Pb on Cu(111), which is non-wetting, and a coarse grained polymer model, which wets the surface, are presented for Pb droplets ranging in size from $\sim 55000$ to $220000$ atoms and polymer droplets ranging in size from $\sim 200000$ to $780000$ monomers. In both cases, a precursor foot precedes the spreading of the main droplet. This precursor foot spreads as $r_f^2(t)=2D_{eff}t$ with an effective diffusion constant that exhibits a droplet size dependence $D_{eff}\sim R_0^{1/2}$. The radius of the main droplet $r_b(t)\sim R_0^{4/5}$ in agreement with kinetic models for the cylindrical geometry studied.

13 pages, 5 figures