| Abstract
| - Wormlike micelles, obtained firstly in anionic surfactant sodium dodecyl trioxyethylene sulfate (SDES) solutionsin the presence of AlCl3, were studied using zero-shear viscosities and freeze-fracture TEM micrographs.Then the effects of inorganic salts with different cations, AlCl3, MgCl2, CaCl2, and NaCl, on the rheologicalproperties and microstructures of the SDES micellar solutions were investigated generally. The steady-shearviscosity followed the Cross empirical equation, and the dynamic vlscoelasticity was well modeled by thesimple Maxwell model. There exists an optimal molar ratio Rm of surfactant to salt at which the micellesreach maximum growth. We find Rm ≤ 1/5 for SDES/NaCl system, and Rm ≈ 1/3 for the other three systems.Variations in the surfactant packing parameter Rp help explain the changes of rheology and microstructure ofthe solutions, according to the cationic radii and charges and the interaction between the cations and surfactantmolecular headgroups. The ability of cations that make the micelles reach a maximum growth followed theorder of Al3+> Mg2+> Ca2+> Na+.
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