The Effects of Additives on Surfactant Foaming Properties

As we have seen, the foaming properties of a surfactant can be related to its solution properties through the cmc. It is not surprising, then, that additives 

Additives that alter the foaming properties of a surfactant through changes in its miceUization characteristics can be divided into three main classes  

TABLE 12.3. Effect of Structure of Organic Additives on CMCs and Foaming Characteristics of Sodium 2-n-Dodecylbenzene Sulfonate Solutions 

Not only does foam stabilization by additives seem to go hand-in-hand with the effect of the additive on the cmc of the surfactant, but there is also a correlation with the relative amount of additive that is located in the interfacial film. The greater the mole fraction of additive adsorbed at the interface, the more stable is the resulting foam. Many of the most stable foaming systems were found to have surface layers composed of as much as 60-90 mol% additive. 

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