Formation of a lamellar phase:Rearrangement of amphiphiles from the bulk isotropic phase into a lamellar fashion

The dynamics of the formation of a lyotropic lamellar arrangement. of surfactant molecules has been studied by means of a contact experiment. Technical grade dodecylbenzenesulfonic acid (HDoBS) was brought into contact with water or an aqueous solution containing sodium hydroxide or sodium hydroxide plus sodium chloride. The phase penetration was followed by light microscopy and freeze-fracture electron microscopy (FFEM). By the FFEM technique more insight has been obtained into the ordering process on a molecular level. The use of FFEM for such an application has not been presented before. In combination with phase diagrams, these techniques offered a mechanism for the formation of the lamellar phase, starting from the bulk surfactant situation. As a first step, water penetrates into bulk liquid isotropic HDoBS, thereby in passing inducing the lamellar order of surfactant molecules. Further maturing of the lamellar phase strongly depends on the type of aqueous phase offered.