Molecular Dynamics Simulation of Heterogeneous Nucleation and Growth of Argon at Polyethylene Films

Heterogeneous nucleation and growth of supersaturated argon vapor at polyethylene surfaces is investigated using molecular dynamics simulation. The specific system is chosen as model for high wettable systems. The simulations are conducted in a nonequilibrium ensemble which includes heat transfer during the condensation process. Temporary density and temperature gradients are developed in the vapor phase. The gradual transition from nearly adsorption behavior close to the binodal to heterogeneous nucleation of a metastable vapor is investigated by stepwise varying the initial saturation of the vapor. By increasing the supersaturation along an isotherm a continuous transition from the layer-by-layer growth to the islands-on-layers one is observed. The results are compared to classical nucleation theory for the heterogeneous two- and three-dimensional growth models. We find for this system that a two-dimensional version of the classical heterogeneous nucleation theory is most suitable to describe the nucleation rate data vs saturation obtained from simulation over a wide range of supersaturation.