The formation of wormlike micelles in anionic surfactant aqueous solutions in the presence of bivalent counterion

The growth and structure of anionic micelles sodium dodecyl trioxyethylene sulfate (SDES) in the presence of bivalent counterion Ca2+ were investigated by means of rheological methods and the technique of freeze-fracture transmission electron microscopy (FF-TEM). It was observed that wormlike micelles could be formed in SDES/CaCl2 aqueous micellar solutions, according to the measurements of zero-shear viscosity η0, complex viscosity |η*|, dynamic moduli (storage modulus G′ and loss modulus G″), and the application of Cox–Merz rule and Cole–Cole plot. The structure was of character of a non-linear viscoelastic fluid and departed from the simple Maxwell model.