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

Competitive adsorption at a planar fluid interface from a binary mixtu re of spherical Lennard-Jones particles of different sizes is investig ated by molecular dynamics simulation. Average particle density profil es and pictures of instantaneous configurations are presented as funct ion of the concentration of small particles, the particle diameter rat io, 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 prefe rentially adsorbed small particles is found to be sensitive to the pac king density in the primary layer and the strength of the interparticl e interactions. The gross features of the model are consistent with ex perimental observations of the competitive displacement of proteins fr om oil/water interfaces by small surfactants.