Properties of anionic–cationic adsorption films:: Part 2

The composition and mutual interactions of the components in anionic–cationic adsorption films have been determined by using a regular solution model for the mixed monolayers. Equimolar mixtures containing sodium nonylsulfonate and decyl- or dodecylpyridinium chloride or bromide have been investigated. The ionic strength of the solutions has been fixed by addition of appropriate amount of inorganic electrolyte (NaCl, NaBr, NaI). It has been found that an increase of the ionic strength and change of the inorganic electrolyte from sodium chloride through bromide to iodide results in a weakness of mutual attraction of the adsorbed components which indicates that these interactions have a mainly electrostatic character. The ionic strength of the solution and the kind of the inorganic electrolyte also distinctly influence the composition of mixed adsorption films. This effect is greater the more different the surface activity is of the mixture components.