Models for Stabilization of Charged Particles with Surfactants in Nonpolar Media

Abstract

Stabilization of charged particles in nonpolar media is one of the most complicated problems in modern colloid chemistry. The attribution to colloid chemistry is absolutely justified in this case: in nonpolar media, charged particles have, as a rule, a supramolecular nature. Low dielectric permittivity of a medium makes the existence of ions in the classical interpretation energetically disadvantageous. The key condition for the presence of charged particles in nonpolar media is their steric stabilization, which requires some revision of the classical concepts of the structure of the electrical double layer, primarily, its diffuse part. Detailed analyzing the structure of the electrical double layer in nonpolar media is of importance because of the high practical significance of electrokinetic phenomena in such systems. This review considers the main models for steric stabilization of charged particles with surfactants in dispersion media having dielectric permittivities lower than 5. The main attention is focused on not only the concentrations corresponding to the formation of reverse micelles, but also on the concentrations below the critical micelle concentration. In addition, nontypical examples of electrokinetic phenomena in organosols are considered.