Effect of tetrabutylammonium bromide on the micelles of sodium dodecyl sulfate

Micellar behavior of sodium dodecyl sulfate (NaDS) was examined in the presence of tetrabutylammonium bromide (TBABr) by surface tension, viscosity, dynamic light scattering (DLS), dye solubilization, and cloud point measurements. NaDS showed enhanced solubilization properties and a remarkable decrease in surface tension and critical micelle concentration (CMC) in presence of TBABr. Both viscosity and DLS showed growth in NaDS micelles (50 mM) above 100 mM TBABr concentration; sphere-to-rod transition and micellar growth observed till 200 mM, above which solution undergoes phase separation. The results are explained on the basis of the binding ability of bulky tetrabutylammonium ion on NaDS.