Monolayer Model Simulations of Mixtures of Amphiphilic Molecules

Abstract

AbstractAthermal Monte Carlo simulations for a mixed monolayer built up from flexible molecules with different chain lengths have been carried out within a cubic lattice model. Only excluded volume interactions are taken into account. The number of chain segments per molecule, the head density, and the mole fraction of each component are varied. It is the aim of the work to investigate the orientational order in such mixtures. The calculated correlation lengths and snapshots did not show any evidence for demixing. In order to understand the effect of mixing on ordering some additional properties of the system have been investigated. Results demonstrating the influence of the mole fraction and chain length on the orientational order parameter, the end‐end distance, the end‐end projection, and the density profiles are presented. These quantities exhibit deviations from an ideal mixing rule. The deviations get stronger with increasing relative chain length difference. The shorter chains do not align in the local environment of long chains.