ABSTRACT
Surfactants are the primary molecular constituents of micelles. They are also called amphiphiles, and certain classes of surfactants are detergents. Surfactants are amphiphilic molecules having separate lyophilic or solvophilic (solvent-loving) groups and lyophobic or solvophobic (solvent-hating) groups (see section C2.3.3). Having both types of group makes a molecule amphiphilic and amphipathic. Micelles are the most prevalent aggregate structure in surfactant solutions and form over a narrow range in surfactant concentration centred around the critical micelle concentration, cmc (see section C2.3.4). This process of micellization is taken, in the so-called pseudophase approximation, as the formation of a two-phase system comprising the continuous solvent phase and a pseudophase consisting of the oily micellar cores. This approximation is convenient for many purposes, but it must not be taken literally, as micellar solutions are generally single-phase isotropic solutions and micelles are thermodynamically reversible aggregates, in dynamic equilibrium with surfactant ‘monomers’ in solution.
