Effect of Hydrophobic Chains on Solubilization of Hydrocarbon and Fluorocarbon Surfactant Mixtures in Aqueous Solution.

We investigated the solubilization behavior of the hydrocarbon surfactant lithium dodecyl sulfate (LiDS) and the fluorocarbon surfactant lithium 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-1-octanesulfonate (LiFOS) in an aqueous solution to determine the controlled release mechanism of solubilizate. The LiDS system solubilized Sudan III, a hydrocarbon compound, whereas the LiFOS system did not, because of the immiscibility of the hydrocarbon and fluorocarbon compounds. The solubilization ability of the LiDS and LiFOS mixtures gradually decreased with increasing LiFOS bulk composition because the micelles mainly composed of LiDS transformed into micelles mainly composed of LiFOS. Furthermore, Sudan III solubilized in the aqueous LiDS was deposited when an aqueous LiFOS was added. The difference in the solubilization behavior between LiDS and LiFOS enabled the controlled release of the solubilizate.