Molecular interaction in Langmuir monolayers - Statistical thermodynamics approach

A regular solution theory for a two-dimensional system with three components of different molecular sizes, adapted from statistical thermodynamics, is used to derive equations describing parameters related to the molecular interactions in mixed Langmuir monolayers. The theory has been applied by examining interactions at the interface for the mixed system of 1-hexadecanol and 1,16-hexadecanediol spread at the water/air interface, basing on experimental data of surface pressure/area (pi/A) isotherms. The obtained results show that the attractive forces between film-forming molecules are much stronger than those between particular amphiphiles and water.