Abstract:
The phase diagrams of anionic surfactant sodium dodecyl sulfonate (SDS) and cationic surfactant cetyl trimethyl amine bromide (CTAB) aqueous mixtures at different temperatures have been measured. The influence of added salt sodium bromide (NaBr) on the aqueous two phase (ATP) regions has been observed. The microstructures of each ATP were observed by TEM. It is shown that there are two lower critical solution temperature (LCST) ATP systems in two regions in which SDS or CTAB is excessive. The ATP regions were enlarged with the increasing temperature. The ATP regions can also be enlarged by adding NaBr and moving to larger mixing ratio of anionic and cationic surfactants. The rate of phase separation can be greatly speeded up by adding NaBr to ATP regions in which CTAB is excessive. However, little effect was observed for ATP regions in which SDS is excessive.