LAMELLAR TO VESICLE TRANSITIONS OF HIGHLY-CHARGED BILAYERS

We study the phase diagram of the binary didodecyldimethylammonium ace tate/water system from 4.4 x 10(-6) to 0.1 volume fraction of surfacta nt using classical and dynamic light scattering, SANS, and electrical conductivity measurements. A thermodynamically stable dilute vesicular phase exists at concentrations below 0.005 surfactant volume fraction . With increased concentration of surfactant a symmetric sponge (L3) p hase and lamellar phase are observed separated by a two-phase region. The symmetric sponge phase exists in the concentration region from 5 x 10(-3) to 2.5 x 10(-2) volume fraction.