Molecular Architecture of Surfactants, Packing Considerations, and

4 MOLECULAR ARCHITECTURE OF SURFACTANTS, PACKING CONSIDERATIONS, AND SHAPES OF MICELLES 

In addition to its simplicity, such a geometric argument can also be used to predict the changes in the structure of the aggregates as variables such as pH, charge, electrolyte concentration, and chain length of the tail are varied. The importance of the relative effects of the head group area and the size of the tails was first emphasized by Tatar (1955), and the details were developed subsequently by Tanford (1980) and others (see Wennerstrom and 

5 Illustration of the geometric parameters for a surfactant and how they influence the size of the micelle. (Redrawn from Israelachvili 1991.) 

Lindman 1979 and Chapter 17 of Israelachvili 1991). In what follows we restrict ourselves to the features essential for illustrating how packing considerations influence the resulting shapes of the surfactant aggregates and ignore the presence of water inside the Stern layer. 

We first define the basic geometric parameters of the surfactants and follow this up with an illustration and a discussion of packing considerations that allow us to predict the shapes of the aggregates. 

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