Dynamics of wormlike micelles under shear

Project title: Dynamics of wormlike micelles under shear
Main applicant: Max Wolff, Division of Materials Physics

Complex liquids have unique flow properties, displaying behaviours between classical solids and liquids due to their broad distribution of relaxation times. The viscoelastic properties can generally be connected to the structure and dynamics of the constituents, which can be addressed by scattering methods. However, experiments addressing the dynamics of complex liquids under shear are very scarce and the structure of very high molecular mass polymer melts and high concentration polymer solutions is not well understood since the Weissenberg effect makes rheological experiments challenging. A specifically designed closed shear device offers unique possibilities to fill both gap.

The repation theory is very sucessful in predicting scaling laws for static polymers by assumming a reptative motion of the single chains confined by entanglements from the other chains. We propose to investigate the dynamics of wormlike micelles, showing similarities to polymer melts with respect to the viscoelastice properties, under shear. We test the predictions of extensions of the reptation theory, like convective constrain release, disentanglement and bending modes. While the physics of wormlike micelles is more complicated they are much easier to investigate experimentally.