Microscopic origins of caging and hyperdiffusive relaxations in hairy nanoparticle fluids

Nanocomposites formed from well-dispersed suspensions of solvent-free silica nanoparticles tethered with flexible polymers are known to exhibit jamming behavior due to interpenetrated chains in the confined space between nanoparticle cores. This talk discusses equilibration processes in such materials by means of small-angle X-ray scattering (SAXS), dielectric relaxation, and rheology measurements. In so doing the talk we explore the microscopic processes responsible for caging and show how cages emerge on the nanoparticle cores. The talk also considers consequences of caging, including hyperdiffusive particle dynamics and yielding. A simple microscopic model for caging and particle clustering is shown to explain both the yielding transition and onset of hyperdiffusive relaxations.