Alcohols three-component phase diagram

The sulfones, sulfolane and 3-methylsulfolane, are shown to function quite well, as cosurfactants with CTAB, in the solubilization of both organophosphorus esters and betahalosulfides. For the organophosphate used, tributylphosphate, it is shown through pseudo-three-component phase diagrams that the sulfone functions as effectively as the alcohol in its role of cosurfactant. Solubilization of chloroethyl ethyl sulfide is less effective when the sulfone cosurfactant is used, but is still a dramatic enhancement over its solubility in water alone. The effect of added salt on the solubilization is reported, as well as the effect of changes in the surfactant-cosurfactant ratio. Preliminary quasielastic lightscattering measurements are also reported for these unconventional systems. 

A phase diagram is a map that indicates the areas of stability of the various phases as a function of external conditions (temperature and pressure). Pure materials, such as mercury, helium, water, and methyl alcohol are considered one-component systems and they have unary phase diagrams. The equilibrium phases in two-component systems are presented in binary phase diagrams. Because many important materials consist of three, four, and more components, many attempts have been made to deduce their multi-component phase diagrams. However, the vast majority of systems with three or more components are very complex, and no overall maps of the phase relationships have been worked out. 

Consider the phase diagram of a three-component system of water, ionic surfactant and medium-chain alcohol, as described in Figure 15.4. At the water comer... 

The fifth main type occurs in systems in which the soap component is not an association colloid of the paraffin chain type but a salt of a bile acid, with its condensed four-ring skeleton with two or three hydroxyl groups and with one carboxyl group at the end of a branched hydrocarbon chain. Figure 29 shows the phase diagram for the sodium cholate-decanol-water system (9). There is no mesomorphous phase but one extensive continuous area with homogeneous isotropic solutions. The cholate and decanol are mutually soluble in the presence of water, as in the case of the soap and the alcohol in the soap-alcohol systems, but here we have the remarkable phenomenon that water and decanol, which are practically insoluble in one another, become mutually soluble in all proportions in the presence of a certain quantity of a bile acid salt. 

When more than three components are needed, two dimensional representation is still possible if two relationships are imposed on the system. For example. Figure 2.18 shows phase diagrams of water, oil, SDS and alcohol. The constant molar ratio 2 SDS molecules for 13 alcohol molecules was imposed onto the system. 

Microemulsions may also be considered as swollen micellar systems, as suggested by Shinoda and co-workers [105-107]. These authors considered the phase diagrams of the components of the microemulsion systems. As discussed in Chapter 10, the phase diagram of the three-component system water/surfactant/ cosurfactant (alcohol) shows two main regions at the water and alcohol corners, namely Li (normal micelles) and L2 (inverse micelles). These regions are separated... 

Figure 9 Effect of the addition of alcohol and cosolvent on the phase diagiam T = 25°C). (a) Three-component diagram water, limonene, and surfactant (Brij 96). (b) Effect of ethanol addition, (c) Effect of ethanol and propylene glycol addition.

The phase behaviour generated upon the addition of a fourth component, for example, a second monodisperse ethoxylated alcohol of different hydrophilic-lipophilic balance, must be mapped in three-dimensional space in the form of a pyramid or phase tetrahedron (Figure 4.8). Each of the four comers of the diagram represent 100 wt% of that particular component, and the three sides of the tetrahedron represent Gibbs triangles describing the phase behaviour of the three possible ternary combinations. 

The physico-chemical formulation deals with the nature of the components, which are at least three, and will be referred to as surfactant (S), oil.(0), and water (W). For the sake of simplicity, the alcohol effect is going to be taken into accoimt as another formulation variable, which is an elegant way of avoiding entering the maze of quaternary diagram phase behavior. 

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