Swelling behavior and local topology of an L(3) (sponge) phase

The swelling behavior of an L(3) (sponge) surfactant phase was studied by the small angle x-ray scattering technique; we show that it is well described by the recently computed swelling law for minimal surfaces In addition, the self-diffusion coefficient D-S of several probes within the bilayers of the L(3) phase was measured by the fluorescent recovery after fringe pattern photobleaching technique. The variation of D-S with the surfactant volume fraction provides a clue for the topology of the surface over which the midsurface of the bilayers is draped. This allows us to determine the location of the neutral surface near the polar-apolar interface of the bilayers.