Transient orientational order and transient positional order in the sponge (L3) phase

The question whether macroscopic physical quantities are suitable to describe the optically isotropic sponge (L3) phase, which occurs in many lyotropic systems, is still a matter of debate. In this paper we analyze recent experimental results, which probed the response of sponge phases to jumps in applied pressure, temperature and electric field. Data obtained from dynamic light scattering are also incorporated into the discussion. As a result it emerges that the experimental data are compatible with the simultaneous occurrence of transient positional and transient orientational order. Additional experiments to further test the results of our analysis are suggested.