Hartley micelle

The minimum in the interfacial free energy predetermines three kinds of geometry in nature spheres, cylinders and planes. Correspondingly, the most stable amphiphile aggregation structures are i) spherical (Hartley) micelles, ii) rod-shaped micelles and anisotropic middle phases, iii) disk-shaped micelles and lamellar mesophases. They exist as aggregates in a water continuum with a hydrocarbon core surrounded by hydrated polar groups (the normal type) and as aggregates in a hydrocarbon continuum (the reverse or inverted type) where water and... 

Stauff and Phi-LiPPOFF are in agreement that the Klein-mizellen correspond to Hartley micelles. Stauff also gives a model of these micelles which finds a place somewhat in between... 

Then there must be a minimum of energy, in other words, a limited Grosz-mizelle of a definite size is produced which is in equilibrium with the Hartley micelles. Stauff (1941) gives the following picture of this Groszmizelle (Fig. 20). These Groszmizellen accordit to Staxjff are produced from associated Hartley micelles. A definite critical concentration cannot be detected there is an equilibrium... 

At the critical concentration of the valeriate (see Fig. 34, transition from a to b) the Hartley micelles are formed, and these perhaps become somewhat flattened with increasing concentration and chains will start to form (Fig, 34c) whereby the X-ray interference of a long spacing makes its appearance. 

When we start from the Hartley micelles there are thus two possibilities of association a loose association of the micelles and an increase in the si2 e of the micelles, whereby plate-shaped aggregates are formed. It must be possible to understand all the phenomena of soap solutions with the aid of these two types of association. 

Clearly more evidence is required before the classical picture of the Hartley micelle is abandoned although, as pointed out by Menger and Boyer, proof in the usual sense of the word is precluded by the assumptions and limitations necessary in the interpretation of data from experiments designed to define the structure of transient aggregates in solution. 

Figure 1.1 Schematic representations of a spherical micelle, (A) and (B) (diameter 5 nm), and of a spherical vesicle, (C) (diameter 20-1000 nm, thickness, 4-5 nm). (A) is the misnamed Hartley micelle as represented in most chemistry and biochemistry books and papers, (B) is a more realistic representation with disordered alkyl chains. Reproduced from reference 16 with permission of the Journal of Chemical Education.

Although the porous cluster micellar model may not be considered completely different from the two-state miceUar model of Hartley in view of the fact that the so-called Stem layer and micellar core of Hartley micelles have never been clearly and precisely defined, a constractive scientific debate has started among the proponent and opponent scientific groups of porous cluster model of micelle. Proponents - and opponents of porous cluster micellar stmcture have published a series of papers over more than a decade since Menger proposed this model in 1979, but, as usual, the findings described in these papers always have almost equally convincing alternative explanations and thus, the real issue on water penetration in micelles remains unclear. 

The simplicity of the Hartley micelle has left it open to criticism, since it fails to adequately explain many experimentally observed phenomena. Models of micelles have been suggested that appear to differ substantially from those of Hartley. Particularly significant differences are a much greater degree of penetration of water into the micelle interior and a relatively smaller interior or core radius. Some of those models appear to better explain some of the solubilization data for hydrophobic additives and the measured or inferred microviscosities of micellar interiors. They have also been used to better explain some results in micelle-catalyzed reactions. The various models of micelles are, of course, just that—models that... 

---