Growth and scission energy of wormlike micelles formed by a cationic surfactant with long unsaturated tails.

The structural and dynamic properties of micellar solutions of erucyl bis(hydroxyethyl)methylammonium chloride blended with 2-propanol, in the presence of KCl, have been investigated by means of light scattering and rheological experiments. In the dilute regime, the micellar growth is larger than expected from mean-field or scaling models. The results obtained in the vicinity of the overlap concentration suggest the presence of large aggregates, with size >100 nm, possibly micellar rings or microgels. In the semidilute regime, the relationship between the zero shear viscosity and the surfactant concentration is described by a power law with an exponent in agreement with the mean-field model of linear micelles. The methods based on the analysis of the temperature dependence of the complex shear modulus to provide a measure of the scission energy are discussed.