HIGHLY SWOLLEN LAMELLAR PHASES IN THE SYSTEM CALCIUM DODECYL-SULFATE,PENTANOL OR HEXANOL, AND WATER

Calcium dodecyl sulfate (CDS) is insoluble both in water and in alcoho ls at room temperature. However, it can be dissolved up to high concen trations in mixtures of water and ethanol, propanol, or butanol. No li quid-crystalline phases are formed with ethanol and propanol at 25 deg rees C but are observed with butanol at higher concentrations of CDS. With pentanol and hexanol, lamellar phases are observed, which can be swollen largely. Neutron scattering measurements of phases with a weig ht ratio CDS:hexanol = 1:1 show stiff lamellae in the concentration ra nge of 1.5-25 wt % CDS. The repeat distance grows linearly with diluti on. The effective thickness for the hydrocarbon part of the lamellae d ecreases to some extent at high CDS concentrations.