One more extreme near the critical micelle concentration: optical activity.

It is reported the discovery of optical activity of micellar solutions of sodium dodecyl sulfate, cetyltrimethylammonium bromide, and poly(oxyethilene)(4)dodecyl ether as typical representatives of anionic, cationic, and nonionic surfactants. The surfactants exhibit dextrorotation. Since the optical activity of the ionic surfactants appears only above the Krafft point, it should be ascribed to micellar aggregates.

Extremes of some foam properties and elasticity of thin foam films near the critical micelle concentration.

The elasticity of open and closed thin foam films is analyzed. The elasticity modulus of a closed film is shown to be additive with respect to contributions from Gibbs elasticity and disjoining pressure. A detailed expression for the film elasticity modulus explains the pronounced maxima of foaminess and foam stability near the critical micelle concentration observed earlier in many experiments.