Rheology of glassy and jammed emulsions

We study the rheology of monodisperse emulsions with various mean droplet sizes. Above a critical volume fraction, these systems will exhibit solid-like behaviors and possess a yield stress. Previous simulation work suggests that for small thermal particles, rheology will see a glass transition; for large athermal systems, rheology will see a jamming transition. However, at the crossover of thermal and athermal regimes, the glass and jamming transitions may be well separated and observed at different volume fractions for a fixed mean droplet size. We conduct an experiment by shearing different sizes of emulsion droplets (500 nm-5 μm diameter) with a rheometer. In this way, we measure rheological properties near the critical volume fraction. By varying the shear rate and particle size, our experiments cover a wide range of Péclet number (the ratio of shear and thermal motions), including the crossover regime.