In-Layer Structuring of Like-Charged Macroions in a Thin Film

A thin liquid film formed from similarly charged macroions dissolved in an electrolyte solution is modeled using the canonical ensemble Monte Carlo method. Simulation studies are performed within a one-component fluid approach; i.e., the model system is composed of the macroions only but using an effective pairwise interaction that incorporates contributions from both the electrostatic nature of the supporting electrolyte and the discrete nature of a polar solvent. The layering phenomenon and in-layer ordering of the macroions in a thin macroion film are analyzed, and the role of electrostatics and excluded volume forces is discussed. We find that the electrostatic forces enhance the overall phenomenon of macroion layering while the excluded volume forces are important for the formation of the surface monolayers and contribute to the macroion structuring within monolayers.