(522j) Life Expectancy and Mileage of Colloidal Bonds in Attractive Colloidal Gels

Colloidal gels exhibit a variety of mechanical and rheological responses to an applied deformation. This rheology is believed to be determined by the kinematics of the interparticle bonds that forms dynamically under flowing conditions. Here, we study the origins of such mechanical and rheological features in short-range attractive colloids with respect to different characteristics of the particulate network. We decouple the role of different forces on particles, and also interrogate the evolution of the colloidal structure at different rates, identified by the strength of shearing and attractive forces. Our results indicate that by increasing the Mason number (Mn), as the ratio between shear and attractive forces, the micromechanics of interparticle interactions changes from attractive to hydrodyanmic dominated, with an intermediate transition regime where the competition between the two results in dynamical heterogeneities. By continuously tracking the interparticle bonds, we present an analysis of their life and death mechanism. We show that at small Mason numbers the old bonds are dominantly responsible for the mechanics of the gel, while at large Masons it is the young ones that determine the rheological response of the fluid. Finally, we present visual mapping of particle bond numbers, their lifetimes and the stress response under different conditions.