Aggregate morphology

Figure 11.23 Structure of polystyrene (PS)-dendr-(NH)32 and aggregate morphology as a function of dendron generation. Reprinted from van Hest et al. (1995). Reprinted with permission from the American Association for the Advancement of Science.

Figure 11.22 (a) Cholesteryl-oligo(L-lactic acid)-(lysine) G2 amphiphiles and (b) variations in aggregate morphology with dendron generation. 

Molecular organization and self-assembly into layers, membranes, vesicles etc., construction of multilayer films [7.1-7.5], generation of defined aggregate morphologies [4.74, 4.75, 7.6-7.8J etc., make it possible to build up specific supramolecular architectures. The polymerization of the molecular components has been a major step in increasing control over the structural properties of such assemblies [7.9-7.13]. 

TABLE 7.1 Relationship between the shape of the surfactant monomer and the predicted aggregate morphology. 

Effective Shape of the Surfactant Packing Parameter Aggregate Morphology Cone <1 /3 P = fj Spherical micelles... 

FIGURE 7.1. Aggregate morphologies of single-chain amphiphiles. 

It is general considered that the driving force for the self-assembly of amphiphilic molecules is a solvophobic effect, more specific in an aqueous environment, this is referred to as the hydrophobic effect. The type of aggregate morphology formed can be predicted... 

The most straightforward morphologies (i.e. spheres, cylinders and bilayers) are obtained by the combination of parameters given in Table 7.3. From this table it is evident that an increasing hydrophobic/hydrophilic ratio results in a change in aggregate morphology from spherical to rod-like micelles to vesicles. 

TABLE 7.3. Packing parameter, mean curvature (H) and Gaussian curvature (K) for different aggregate morphologies. 

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