Cohesive and Non-cohesive Adsorption of Surfactants at Liquid Interfaces

The ability of soluble nonionic surfactants to form liquid expanded (LE) phase is investigated. It is found that the adsorption behavior of nonionic surfactants at liquid interfaces falls into one of two well-defined types: cohesive (with liquid expanded phase) and non-cohesive behavior (without liquid expanded phase). The effect of surfactant structure and properties of the medium on the adsorption parameters of both adsorption types are analyzed. A model of the adsorption constant is proposed, which compares well with experimentally observed values.