Cloud Point Phenomenon in Ionic Micellar Solutions: A SANS Study

摘要

We have observed the cloud point (CP) in the ionic surfactant sodium dodecyl sulfate (SDS) in the presence of 0.2 M tetra-n-butylammonium bromide (Bu_4NBr). To study the changes taking place in the system approaching the CP, we have performed SANS studies with 0.3 M SDS as a function of [Bu_4Nbr] and temperature. The spectra obtained with Bu_4NBr addition show micellar growth. The temperature increase has different effects on 0.1 and 0.15 M Bu_4NBr systems. Further, the ionic micelles show characteristics of nonionics for 0.2 M Bu_4NBr as the temperature was raised. The overall phenomenon is conjectured in light of gradual displacement of water form the clefts which characterize the micellar surface.