Disc-shaped micelles

For ionic amphiphiles the first formed aggregates are closely spherical. At higher amphiphile concentrations there is a tendency for the formation of rod-shaped micelles168. Also the addition of salt favours the rod-shape aggregates33. It has been suggested that disc-shaped micelles also occur160 but experimental evidence in favor of this view has only been obtained for mixed micelles of lecithin and sodium cho-late179. ... 

Fig. 1 Association colloids (A) spherical micelle (B) cylindrical micelle (C) flattened disc-shaped micelle (D) microtubular micelle (E) inverted micelle and (F) micelle swollen by the presence of solubilized lipid soluble drug.

It is observed between the L, and in a narrow band of 34-38% surfactant between 7.5 and 23.4 °C and is made up of disc shaped micelles (Fig. 25). The phase exists up to -12% surfactant (and to = 80% in a biphasic region with water). Clouding is seen over a wide concentration range (up to >90% surfactant) with a lower critical temperature of 33.2°C. 

Under just the right conditions, a mixture of a highly polar liquid, a slightly polar liquid, and an amphiphilic molecule form micelles that are not spherical. They can be rodlike, disc-like, or biaxial (all three axes of the micelles are different). These anisotropic micelles sometimes order in the solvent just as liquid crystal molecules order in thermotropic phases. There is a nematic phase of rod-shaped micelles, another nematic phase of disc-shaped micelles, and even a biaxial nematic phase, in which the molecular axes transverse to the long molecular axis partially order. Chiral versions of these phases with the same structure as the chiral nematic phase also form. 

Moreover, on the same basis, one can rather readily deal with the other geometries cylinders, planar bilayers, and curved bilayers, thus enabling theoretical calculations of the relative stabilities of spherical, rod-shaped, and disc-shaped micelles as well as geometrically closed vesicles [60]. 

Janus-type micelles were reported via electrostatic interaction between two double-hydrophilic block copolymers poly(acrylic acid)-fc-poly(acryl amide) (PAA-fc-PAAm), and poly(2-methylvinylpyridinium iodide)-fe-poly(ethylene oxide) (P2MVP- -PEO). The aggregate forms disc-shaped micelle with PAA/P2MVP complex coacervate core and microphase-separated asymmetric corona, with two distinct domains formed by PEO and PAAm. Eigure 14.20 shows a TEM image of Janus-type micelles... 

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