ABSTRACT
The rheology and dynamics of giant micellar solutions have attracted special attention because subtle changes in surfactant, cosurfactant, temperature, added electrolyte, and counterion can produce enormous changes in dimensions, flexibility, and interactions. Since giant micelles exhibit shear thickening in the dilute regime, strong viscoelasticity, high viscosity at low shear rates and shear thinning at higher concentrations, they have been commercially used as drag-reducing agents, in home and care products, and in oil field applications. This chapter focuses on developments on the nonlinear rheology of giant micelles. It presents the general rheological patterns of the systems and of mixed surfactant solutions. The chapter discusses the relevant aspects of the shear-thickening transition and the possible morphology and mechanism of this transition. It examines the shear-banding transitions in semidilute and concentrated systems. The decrease in viscosity after the maximum has been attributed to the occurrence of branched micelles, which causes the formation of sliding points that allow faster relaxation.
