Micelle shape globular

We shall deal with ionic and zwitterionic amphiphiles. These can take on a confusing variety of different shapes and sizes some aggregate into small spherical or globular micelles, others appear to form long cylindrical micelles, while others coalesce spontaneously into vesicular or lamellar bilayers. 

As discussed in section 5, once aggregation numbers exceed a certain limit, it is no longer possible to pack amphiphiles into spheres. If the aggregation number is not too large, we can expect micelles to take a globular, near spherical, shape and now consider corrections to the theory which arise from this non-sphericity. 

Fig. 6 Cryo-TEM micrographs show the shape of the aggregates in the course of the vesicle-to-micelle transformation in the MGO/CTAB mixture. (A) Coexistence of globular micelles, elongated micelles that are probably ribbon-like, and vesicles (lipid mole fraction 0.47). (B) Perforated vesicles (lipid mole fraction 0.64). Reproduced from Ref. [30] with permission of the American Chemical Society.

One may observe monolayers, spherical (globular or rotund) micelles, cylindrical (tubelike or wormlike) micelles, and bilayers. (The more ordered liquid crystals are treated in the following.) The size and shape distributions of surfactant aggregates in solution... 

In concentrated aqueous surfactant solutions, the sizes and shapes of the aggregates are also influenced by interaggregate forces. This leads to positionally ordered structures characterized by long-range orientational alignment and spatial periodicities that cannot be ascribed to spherical micelles [108]. Nevertheless, all three classical structural shapes—spheres, cylinders, and planes—are respectively revealed in hexagonal, discrete (globular) micellar. 

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