Concept of Critical Micelle Concentration CMC

The CMC is usually determined experimentally by plotting some property as a function of concentration and extrapolating the results at low and high concentrations to an intersection point. It is evident that the value obtained will depend on the type of representation used as well as on the physico-chemical quantity considered. For surfactants with low CMCs, micelle formation begins abruptly and the uncertainties involved are rather small while this is not always the case for surfactants with high CMCs. When the variation of CMC with chemical or physical factors is considered it is often essential to use CMC values obtained in a consistent way. 

A large number of experimental techniques can be utilized to determine CMC values, the most popular ones being investigations of electrical conductance, surface tension and the solubilization of a compound having a low solubility in water. The 

A most valuable compilation of CMC data has been presented by Muketjee and Mysels3) who in addition to an extensive tabulation of CMCs for various systems discuss the CMC concept as well as plot procedures and experimental techniques for CMC determination. In Table 2.1 we give selected examples of CMC values taken from Ref.3.  

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