Microrheology of giant-micelle solutions

¹ Department of Physics, University of Fribourg - CH-1700 Fribourg, Switzerland
² GDPC, Université de Montpellier II - 34095 Montpellier Cedex 05, France

Corresponding author: Frank.Scheffold@unifr.ch

Received: 14 September 2001
Accepted: 4 December 2001

Abstract

Optical tracer-microrheology has been applied to study the rheological properties of a concentrated surfactant solution. Under the chosen conditions these surfactants self-assemble to form giant polymer-like micelles, resulting in a strongly viscoelastic liquid. A novel approach to the analysis of the local dynamic properties of tracer particles is presented, based on a combination of single- and multi-speckle diffusing wave spectroscopy (DWS). With this technique we could significantly extend the accessible frequency range to the key rheological properties as given by the loss and storage modulus, and . A study of the high-frequency range, not accessible to standard techniques, shows good overall agreement with conventional models. However, we find a distinct temperature dependence of the characteristic modulus G₀ incompatible with the simple picture of a single relaxation process.