Box 26-1 Surfactants and Micelles

A surfactant is a molecule that accumulates at the interface between two phases and modifies the surface tension. (Surface tension is the energy per unit area needed to form a surface or interface.) One common class of surfactants for aqueous solution are molecules with long hydrophobic tails and ionic head groups, such as 

A micelle is an aggregate of surfactants. In water, the hydrophobic tails form clusters that are, in effect, little oil drops insulated from the aqueous phase by the ionic head groups. At low concentration, surfactant molecules do not form micelles. When their concentration exceeds the critical micelle concentration, spontaneous aggregation into micelles occurs.8 Isolated surfactant molecules exist in equilibrium with micelles. Nonpolar organic solutes 

Fischer, Ion-Pair HPLC Determination of Sugars, Amino Sugars, and Uronic Acids, Anal- Chem. 2001, 

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