X-ray investigation of colloidal glasses under shear

Understanding glassification or dynamical arrest is one of the grand challenges of material science and is a topic of great current interest. It is a central observation in soft matter systems as well as glass forming molecular systems that -- with increasing density or decreasing temperature -- the motion of the particles or molecules slows down and eventually becomes arrested. Understanding this dynamical arrest as well as relaxations in the arrested state are fundamental problems, which to a large degree remain unanswered. We use a novel combination of rheological measurement and small angle x-ray scattering (at the synchrotron DESY in Hamburg) to study structure factor of dense suspensions under shear and during relaxation. The suspensions consist of silica particles 50nm in diameter. We observe clear changes of inter particles distances and configurations due to the different shear rates. Together with future dynamic x-ray measurements we aim to develop a universal scale-bridging understanding of dynamic arrest.