Cubic lyotropic liquid crystals

Set-ups for isoplethal and hygroscopic studies of lyotropic systems: (a) a flat capillary isfilled with a surfactant/water mixture of a predetermined composition; (b) a droplet of the surfactant is surrounded by a humid atmosphere; the relative humidity at the crystal surface is determined by the temperature difference ΔT=Ts − Tb.

Concentration of water in a Ia3d crystal depends on the temperature difference ΔT=Ts − Tb between the water reservoir and the crystal. When ΔT increases, the Ia3d - L2 transition is approached and the facet-by-facet melting of the crystal surface occurs.