Gemini surfactants interfaces, behavior

Zana, R. (2002) Dimeric (gemini) surfactants effect of the spacer group on the association behavior in aqueous solution./. Colloid Interface Sci., 248 (2), 203-220. 

The next section discusses chemical structures, synthesis, and purification of gemini surfactants. Section III reviews the behavior of gemini surfactants in solutions below the CMC. Section IV deals with their behavior at interfaces. The fifth section reviews micelle formation and solubilization. Section VI deals with micelle properties. Microstructure of aqueous solution of gemini surfactants, rheology of these solutions, and mixed micellization are considered in the following three sections. Section X deals with the phase behavior of... 

The real difficulty when dealing with gemini surfactants lies in the purification of the raw surfactants. The purification of the crude gemini surfactants is essential, particularly in studies of adsorption and behavior at interfaces. The purification procedures are somewhat easier for the quaternary ammonium gemini surfactants. Sophisticated procedures must often be used. Indeed, one or more reaction steps that leads to gemini surfactants usually involves the two ends of some intermediate compound. This reaction rarely reaches full completion. It results in the formation of a mixture of mono- and difunctionalized compounds. Their separation is usually achieved through chromatography. 

Extensive surface tension measurements have been performed on aqueous solutions of gemini surfactants with the purpose of investigating their behavior at the air solution interface (measurement of surface area a occupied by one surfactant molecule at the interface) and determining CMCs. The surface areas a were obtained from the slope of the variation of the surface tension 7 with In C (C = surfactant concentration) using the Gibbs expression of the surface excess concentration T ... 

The behavior of gemini surfactants at the air-solution interface has been extensively investigated and some important results are summarized as follows ... 

In 1997 Esumi and Ueno [1] edited a book on the structure-performance relationships in surfactants, in which the authors stress the need to understand the properties and performance of surfactants at various interfaces such as air-liquid, liquid-liquid and solid-liquid. The book has a few chapters on adsorption theories and some information on the microstructure of nonionic surfactants in solution, some modeling aspects of the association and adsorption of surfactants, and several chapters on the particular behavior of specific surfactants (polymeric, gemini, bile acids, and others) in solution. No significant clear guidelines... 

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