Determination of Micellar Weights for Di-Alkyl Sodium Sulfosuccinates in Anhydrous and Hydrous Hydrocarbon Solutions

Previous studies have demonstrated that di-(2-ethylhexyl) sodium sulfosuccinate, dissolved in various hydrocarbon solvents, is capable of solubilizing large amounts of water, whereas closely related compounds such as the di-n-octyl and di-n-hexyl derivatives exhibit negligible solubilizing capacity. In view of these observations the micellar size of these three compounds in n-octane was measured by light scattering. Large differences in micelle weight between di-(2-ethylhexyl) sodium sulfosuccinate in n-octane (13,000) and the other compounds (about 200,000) suggested significant role for the 2-ethyl side chain. The active participation of water in the organization of these micelles is suggested by significant changes in micellar weight, well in excess of that accounted for by the added amount of water. The influence of different hydrocarbon solvents on micellar weight also was found to be quite significant.