SPONGE PHASE-BEHAVIOR IN CONCENTRATED SURFACTANT-ALCOHOL-BRINE SYSTEM

The sponge phase monodomain extending from the brine corner to the alc ohol corner of an ionic surfactant-alcohol-brine phase diagram is firs t detailed and then investigated by electrolytic conductivity and refr active index measurements. Upon progressive dimunition of the brine fr action of the sponge phase, the ionic conductivity suffers from two gu mps corresponding to two respective critical concentrations, while the variation of the refractive index remains linear but exhibits two slo pe changes. According to the phase diagram observations we propose one scenario, in agreement with theoretical predictions, to explain these results in terms of continuous structural transformations of the amph iphilic membrane from the swollen sponge phase to the inverse micellar phase.