STRUCTURE AND AGGREGATION OF LITHIUM DODECYL-SULFATE MICELLES IN THE PRESENCE OF A MACROCYCLIC CAGE - A SANS STUDY

At pH=12, a macrocyclic cage CESTO is a neutral molecule known to complex Li+ in aqueous solution. We study the effect of addition of CESTO on the aggregation behavior of lithium dodecyl sulfate (LDS) by small angle neutron scattering. In aqueous solutions the LDS molecules form micelles of quasi-spherical shape with aggregation number of 90 and fractional ionization of 18%. Upon addition of 0.5 to 1 and 1 to 1 molar ratios of CESTO to the solutions, the aggregation number increases but the ionization reduces due to the complexation of lithium ions by CESTO. This is also accompanied by the decrease of hydration number on the micellar surface.