Dynamical properties of wormlike micelles

In certain aqueous surfactant solutions there is good evidence for the existence of long, flexible cylindrical micelles, which can form an entangled mass reminiscent of a polymer solution. This can lead to spectacular viscoelastic behavior, at very low surfactant volume fraction. The major difference from ordinary polymer solutions is that the micelles are continually breaking apart and reforming. A review of the dynamical properties of these systems is presented. In particular we discuss the procedures and limitations for obtaining the structural, kinetics and rheological parameters by combining T-Jump, Light Scattering and rheometry experiments. The concentration dependences of these parameters are compared to the predictions of the theoretical models. The effects of micellar branching and of the electrostatic interactions are discussed. Finally an attempt of classification of the different systems, based on the effect of the surfactant concentration on the viscoelastic behavior is proposed.