Phase transitions in colloidal systems part I: Refractometric study of the binary system SDS plus water or pentanol-1+water and the ternary system water plus SDS+pentanol-1 at 298.15 K.

The monophasic ranges for the binary systems water+SDS and water+pentanol-1 and for the ternary system water+SDS+pentanol-1 has been studied by means of refractometric experiments at 298 K. The curves of refractometric index versus the composition of the system, has shown the existence of several transitions labeled successive critic micellar concentrations. These transitions are detected by a change of the variation of the refractive index. We have evidenced the very importance of the pentanol-l in these amphiphilic solutions, acting as a surfactant or as an oil according the concentration. For these systems it is possible to better understand the phase inversion phenomena. At last, we present the phase diagram indicating the concentration range of the different microstructures.