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 disklike micellar nematic phase to the lamellar smectic phase of decylammonium chloride-ammonium chloridewater as a function of temperature. We show direct visual evidence of the size and shape of the aggregates in the nematic phase, the mechanism of the nematic-smectic transition, and the origin of the residual in-plane order in the smectic phase. These observations are consistent with previous scattering, conductivity, and NMR measurements on this system.