The interface between the lamellar and the sponge phases

We have studied the interface between the sponge phase and the lamellar pha se in different lyotropic systems. Bilayers of the lamellar phase are eithe r tilted, or tangential to the interface. According to a current model, the situation depends on the values of the elastic constants. We have investig ated the cyclohexane/SDS/water/pentanol system in which the elastic constan ts can be changed by tuning the concentration phi of magnetic particles in cyclohexane and we have observed a transition between the two types of inte rface. Finally the magnetic properties have been used to estimate the very low interface tension.