MOLECULAR-DYNAMICS SIMULATION OF COMPETITIVE ADSORPTION OF SPHERICAL-PARTICLES OF DIFFERENT SIZES

Competitive adsorption at a planar fluid interface from a binary mixture of spherical Lennard-Jones particles of different sizes is investigated by molecular dynamics simulation. Average particle density profiles and pictures of instantaneous configurations are presented as function of the concentration of small particles, the particle diameter ratio, the particle adsorption strength, and the relative strength of the unlike interparticle attraction. The presence of a distinct secondary layer of displaced large particles outside the primary layer of preferentially adsorbed small particles is found to be sensitive to the packing density in the primary layer and the strength of the interparticle interactions. The gross features of the model are consistent with experimental observations of the competitive displacement of proteins from oil/water interfaces by small surfactants.