ABSTRACT
Key ingredients in a physicochemical characterization of a microheterogeneous surfactant self-assembly system are (1) phase stability and phase behavior, (2) microstructure, and (3) local molecular arrangements, interactions, and dynamics. Microemulsions constitute but one type of surfactant self-assembly, and any attempt to understand or characterize microemulsions without a broad picture of surfactant systems will be rather meaningless. Microemulsions are, in contrast to (macro)emulsions, thermodynamically stable single-phase systems. They are isotropic solutions, like micellar solutions, with no long-range order. Microstructures of surfactant self-assembly systems show an enormous degree of polymorphism. We may classify structures in three ways (see Figs. 1 and 2):
Phases that possess long-range order and periodicity and those that do not.
Monolayer and bilayer structures.
Phases with discrete surfactant self-assemblies and phases that have self-assemblies that are infinite in one, two, or three dimensions.
