Surfactant, Water, and Organic Material Ternary Systems

Ionic Surfactant, Water, and Organic Material Ternary Systems 

Let us consider an isotherm of a water-ionic amphiphile binary mixture above the Krafft point (for example, water-sodium octanoate) [6], At an amphiphile concentration of 7% (the critical micellar concentration), the micellar isotropic solution LI appears and lasts up to 41%. Between 41 and 46% is the miscibility 

The solubility of a molecule exhibiting dipole-dipole cohesive forces and low H-bonding cohesive forces, such as methyl octanoate, is greater than that of a hydrocarbon, but nothing particular happens in the center of the phase diagram. 

The solubility of n-decanol in the LI phase is also important (up to 12% at the end of the LI phase). The LI phase is accountable for the observation of oil-inwater (o/w) microemulsions. The La domain, generally located in the middle of the diagram, points toward the water side for a critical surfactant-to-cosurfactant ratio. (A 1 2 sodium octanoate to n-decanol ratio leads to a lamellar phase with as little as 17% surfactant-cosurfactant mixture.) In some cases, such as for octyl trimethylammonium bromide (OTAB)-hexanol-water, the lamellar phase already exists for 3% hexanol + 3% OTAB  

The practical interest of a lamellar liquid crystal lies in its suspending capability. A lyotropic liquid crystal exhibits a viscoelastic behavior that allows suspension of solid particles for a very long time. The lamellar phase is additionally characterized by an ideal critical strain to provide the suspension with good resistance to vibrations and convections, without impairing its flowability with too great a viscosity. 

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