Critical micelle concentration amphoterics

For amphoteric surfactants, the critical micelle concentrations (CMCs) are often stated. However, most studies concerning the CMC have centred around betaines and the information extrapolated or applied to the other types of amphoteric surfactants. 

Figure 3. Temperature variation of the critical micelle concentrations of three amphoteric surfactants in 2.1% total dissolved solids brine solutions. (From Stasiuk and Schramm [55]. Copyright 1996 Academic Press, New York.)...

The cationic charge on a polymer affects its behavior considerably when surfactants are included in formulations. Cationic polymers (a member of the broader class of polymers termed polyelectrolytes) usually interact strongly with anionic surfactants, weakly with cationic surfactants, and unpredictably with nonionic and amphoteric surfactants (14,167-169). Anionic surfactant binds to cationic polymers at concentrations well below the critical micelle concentration (cmc). The low surfactant concentration where polymer and surfactant begin to interact is known as the critical aggregation concentration (cag). 

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