Key parameters of adsorption layers are the dynamics of adsorption during their formation, the equilibrium parameters of adsorption, and the rheological behaviour, including the elasticity and viscosity of dilation and shear (in a broad frequency interval). At the interface between two immiscible liquid, such as water and oil, molecules adsorb and partly pass into the oil phase. The distribution of the surfactant between the two phases is given by the distribution coefficient.