A lattice model of a liquid supported monolayer of amphiphile molecules: Mean-field analysis

We describe a lattice model for amphiphile monolayers in which amphiphile configurational flexibility and amphiphile–amphiphile interaction in and out of the surface layer are explicitly treated. The analysis employs a mean-field approximation based on the work of Scheutjens and Fleer. The density distribution as a function of surface coverage and the equation of state of the monolayer are predicted. Monte Carlo simulations of the same model as treated in the mean-field approximation show that the predicted density profile is quite accurate except near φ=0 and that the film thickness as a function of surface coverage is well represented except near φ=0, but that the predicted liquid–gas phase boundary is rather inaccurate.