SANS measurements on micellar systems

Another interesting type of surfactant are double-chain amphiphiles. As an example of this surfactant-type hexadecyloctyldimethylammoniumbromide (CieCgDMABr) has been investigated. Here just above the cmc globular aggregates are formed whereas above a second transition concentration relatively short (150 A) rod-like micelles are formed [108]. 

However, anisometry of the micellar aggregates is a necessary (yet not sufficient) prerequisite of liquid crystal formation. Indeed, at higher concentrations many perfluoro surfactants are known to form nematic, lyotropic, liquid, and crystalline phases [109]. One such system is the tetramethylammoniumperfluorononanoate (TMAPFN) which exhibits a nematic phase over a relatively large concentration range but only in a small temperature interval [91]. This system has been studied in detail by SANS [92]. The experiments showed that 

The growth process of the large micellar structures, which are strongly aligned, has been studied in more detail by transient SANS experiments. In these experiments the shear rate for the samples was raised stepwise from zero to a certain finite value. These experiments showed that the large micelles grow according to the Avrami law 

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