Breaking Down ‘Tough’ Colloidal Gels: A Close-Up View

The viscoelastic properties of gels formed when interacting colloids suspended in a solvent attract to create a percolated network make them ideal for material applications ranging from food to manufacturing. At small strains, these gels are characterized by elastic, system-spanning networks that fluidize under increasing applied stress. Previous work has shown that the breakdown, or yielding, of silica colloidal gels can be tuned by modifying the surface topography of individual colloids to introduce roughness. This suggests that microscale interactions are key to controlling bulk material properties. In this work, we investigate the microstructural network interactions in thermo-reversible rough-particle gels that delay the onset of plasticity. Using a high-speed "rheo-confocal" microscope, we capture changes in the system's global behavior and microstructure simultaneously.