Rheology of viscoelastic anionic micellar solutions in the presence of a multivalent counterions

The growth and structure of anionic micelles sodium dodecyl trioxyethylene sulfate (SDES) in the presence of a multivalent counter-ion, Al³⁺, were investigated by means of rheological methods and the technique of freeze-fracture transmission electron microscopy. It was found that wormlike micelles and network structures could be formed in SDES/AlCl₃ aqueous micellar solutions, according to the measurements of the zero-shear viscosity, the complex viscosity and the dynamic moduli (storage modulus and loss modulus), and the application of the Cox–Merz rule and a Cole–Cole plot. The cyclic shear test, the plateau modulus and the relaxation time were also studied to express the rheological properties of the wormlike micellar solutions. The structure was of a character of a nonlinear viscoelastic fluid and departed from the simple Maxwell model. Received: 23 November/2000 Accepted: 31 January 2001