FLUID MEMBRANES IN THE SEMIRIGID REGIME - SCALE-INVARIANCE

We investigate here the swollen lamellar phase L(alpha) and the anomalous isotropic (sponge) phase L3 of the ternary system AOT/brine using neutron and light scattering. We first measure the excess area of bilayers from the deviations to the simple swelling behavior and so obtain an evaluation of the mean curvature rigidity K of the bilayers. K is found quite high K almost-equal-to 3 k(B) T and is basically the same in both L(alpha) and L3. Correspondingly, the persistence length zeta-K of the bilayer is of the order of 10(6) angstrom so that the samples are in the << semi-rigid regime >> at all practical dilutions. The scale invariance of the statistics of the fluid bilayers expected for such regime is then checked by comparing the neutron and light scattering patterns of samples of different concentrations.