Lattice model of conformational transitions in multilayer surfactant films

Abstract

A lattice model is presented for the investigation of orientational and conformational transitions in thin Langmuir films of bipolar surfactant molecules. The model is developed to describe the molecular structure of thin surfactant films at the liquid–vapour interface. Molecular density distribution profiles are examined for different conformational states and surface pressures. The effect is studied of the position of a second polar group along the surfactant molecule chain on the surface area isotherms. The film's collapse into a multilayer state is investigated and an interpretation at the molecular level is given of the collapse transition. Results are compared with data from continuous models for the liquid–surfactant–vapour interfaces.