L(3) (SPONGE) PHASE IN THE VERY DILUTE REGIME - SPONTANEOUS TEARING OF THE MEMBRANE

We use light scattering and conductimetry to investigate the very dilu te range of the domain of existence of the sponge (L(3))phase in the q uaternary OBS/pentanol/brine system. In this part of the phase diagram we find a line of maximum turbidity where the scattered intensity sho ws a very sharp maximum and has a pure Ornstein Zernicke q-dependence. These features are not consistent with what is expected close to the symmetric asymmetric transition line. We question the possibility of t he spontaneous tearing of the membrane first considered on theoretical grounds by Huse. and Leibler (Phys. Rev. Lett. 66 (1991) 437).