Electron microscope observation of the smectic-nematic transition in a lyotropic liquid crystal.

We observe via freeze-fracture transmission electron microscopy the transition from the disc-like micellar nematic phase (N (L)) to the lamellar smectic phase of Decylammonium Chloride - Ammonium Chloride - Water as a function of temperature. In the nematic phase, the size and shape of the micelles are consistent with previous X-ray and neutron scattering data. The nematic to smectic transition occurs by the individual micelles packing closely next to one another. Eventually, the micelles fuse together to form a continuous smectic bilayer. Micelles are sometimes observed to be merging into rods at the edge of a bilayer which is in the process of forming. These observations are also consistent with conductivity and NMR measurements on this system which suggest a second-order phase transition.