Dynamical arrest transition in nanoparticle dispersions with short-range interactions.

We measure the dynamical arrest transition in a model, thermoreversible, adhesive hard sphere dispersion. At low volume fractions ϕ, below the critical point, gelation occurs within the gas-liquid phase boundary. For ϕ slightly below and above the critical concentration, the phase boundary follows the predicted percolation transition. At high ϕ, it melds into the predicted attractive-driven glass transition. Our results demonstrate that for ϕ above ∼20% physical gelation is an extension of the attractive-driven glass line and occurs without competition for macroscopic phase separation.