The motions of the particles on the substrate of a drying sessile colloidal droplet of water were measured using multiparticle tracking. Droplets with different concentrations (0–250 mM) of sodium chloride (NaCl) were compared. Several statistical quantities were proposed to characterize the heterogeneous behaviors of the particles and distinguish the effects of the flow field and the substrate interaction. For the salt-free droplet, most of the particles were nonadsorbed and mobile without friction. With the presence of salt, the fraction of the adsorbed particles increases with increasing evaporation time and the initial salt concentration, which was explained by Derjaguin–Landau–Verwey–Overbeek interaction. The fraction of mobile particles is mostly frictionless for all samples. At low salt concentrations, the velocity of mobile particles increases with the evaporation time to a peak and then decreases. The velocity is lower for higher salt concentrations. The effect of salt on the nonadsorbed particles was attributed to the electrokinetic effect.

•Laponite dispersed and gelled the droplets of the water-in-oil emulsion.•The clay-filled emulsion shows higher modulus and yield stress than the clay-free one.•The droplet elasticity also contributes to the nonlinear viscoelasticity.The effect of droplet elasticity on the linear and nonlinear viscoelasticity of water-in-oil emulsions was studied by comparing two kinds of emulsions: one with pure water as droplets, the other with a suspension of hectorite clay as droplets. The clay-filled emulsion had high droplet elasticity due to the gelation of the clay suspension. As the water-to-oil volume ratio ϕ increased, the emulsions changed from liquid-like state to solid-like state as the droplets formed a jammed state. Effect of droplet elasticity was most significant in the jammed state, where the clay-filled emulsion showed a much higher plateau modulus than the clay-free one. Nonlinear viscoelasticity was observed by the large amplitude oscillatory shear (LAOS) rheology. The Lissajous curve was dissected into the cage-yielding and cage-restructuring parts, and the cage modulus Gk in the nonlinear viscoelastic regime was higher for clay-filled emulsion than the clay-free one in the jammed state due to the contribution of the droplet elasticity. The droplet elasticity was found to contribute to the nonlinear viscoelasticity of the emulsions.Effect of droplet elasticity on the nonlinear viscoelasticity of concentrated emulsions were studied.