Freeze-fracture studies of ordered ionic micellar solutions.

We observe using freeze-fracture electron microscopy the transition from the disc-like micellar nematic phase to the lamellar smectic phase of decylammonium chloride - ammonium chloride - water as a function of temperature and water content. In the nematic phase, the micelles form independent, disc-shaped aggregates of 6 - 10 nm in diameter (depending on water fraction) and 3 - 5 nm thickness. Near the nematic - smectic transition, individual micelles pack together into orderly rows within the smectic planes and retain their identity well below the transition temperature. These micelles are the origin of the residual in plane scattering found in X-ray scattering experiments.