ABSTRACT
Consider the interaction between a pair of surfactant-stabilized colloidal particles. When two such particles approach each other, a situation arises as sketched in Fig. 1. In the classical interpretation the Gibbs energy of interaction, ∆G(h), where h is the distance between the particle surfaces (or between the head groups of the surfactant), is obtained by estimating its contributions: ∆elG for the double-layer part, ∆vdwG for the van der Waals contribution, ∆entrG accounting for changes in the entropy of the surfactant upon interaction, etc. Such interpretations are essentially static; at any moment the Gibbs energy is computed under the assumption that the structures of the surfactant layer and ionic double layers are at equilibrium. Typically, classical (statistical) thermodynamics is invoked for the analysis.
