Kinetics of surface enrichment: a molecular dynamics study

Abstract

We use molecular dynamics to study the kinetics of surface enrichment (SE) in a stable homogeneous mixture (AB), placed in contact with a surface which preferentially attracts A. The SE profiles show a characteristic double-exponential behavior with two length scales: ξ-, which rapidly saturates to its equilibrium value, and ξ+, which diverges as a power-law with time (ξ+∼t^θ). We find that hydrodynamic effects result in a crossover of the growth exponent from θ≃0.5 to θ≃1.0. There is also a corresponding crossover in the growth dynamics of the SE layer thickness.