Clouding in charged micelles as studied by SANS

Charged micellar solution of sodium dodecyl sulfate (NaDS) in presence of quaternary salt tetrabutylammonium bromide (TBABr) shows a clouding on increasing temperature. Small-angle neutron scattering (SANS) measurements have been performed on equimolar (25 mM) solution of NaDS and TBABr at different temperatures below and above the cloud point. Micelle size increases and average charge on the micelle decreases on approaching the cloud point. Micelles coexist with clouding phase at the cloud point and even after much higher temperature. Contrast variation SANS study has been used to understand the mechanism of clouding in this system.