saa as wetting agent
A surfactant, when dissolved in water, lowers the contact angle between a solid surface and a liquid thereby aiding the displacement of air at that surface by the liquid.
Absorbed materials are divided into two groups; those that form soluble monolayers and those that form insoluble films. The distinction is made on the basis of the solubility of the adsorbate in the liquid subphase, e.g. amyl alcohol may be said to form a monolayer on water, while cetyl alcohol would form an insoluble film on the same sublayer. This is only an arbitary distinction, for the insoluble films are in effect the limiting case of those compounds that form soluble monolayers at liquid interfaces.
Application of Amphiphiles
Sometimes amphiphiles which form soluble monolayers aggregate to produce micelles. After the interface is saturated, some SAA falls out of solution and enter into the oil/water phase. As more SAA is added any SAA that cannot fit in the interface will falls out of the interface. At a certain concentration (critical micelle concentration), micelles started to form. But if too much SAA were added, micelles will start interacting with each other, causing coalescence (phase separation). For example, oil micelles will start coming together which is irreversible.