Coating critical micellar concentration

Fig. 3 Mechanism for the synthesis of a hexagonal silica thin film by dip coating. This is zoomed in at the substrate-bulk solution interface. The dotted line indicates the second critical micelle concentration, above which the micelles form cylindrical micellar rods. These rods then begin to assemble at the air-liquid interface and the liquid-substrate interface. (From Ref. l)...

The value of the critical micelle concentration (CMC) is an important parameter in a wide variety of industrial applications involving adsorption of surfactant molecules at interfaces, such as foams, froths, emulsions, suspensions, and surface coatings. It is probably the simplest means of characterizing the colloid and surface behaviour of a surfactant solute, which in turn determines its industrial usefulness. Many industrial processes are also dynamic processes in that they involve a rapid increase in interfacial area, such as foaming, wetting, emulsification and solubilization. First, the available monomers adsorb on to the freshly created interface. Then, additional monomers must be provided by the breakup of micelles. Especially when the free monomer concentration (i.e. CMC) is low, the micellar breakup time or diffusion of monomers to the newly created interface can be rate-limiting steps in the supply of monomers, which is the case for many nonionic surfactant solutions (3). 

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