Breakup dynamics of water-in-water droplet generation stabilized by nanoparticles in T-junction microchannel

Abstract

The polyethylene glycol (PEG)-rich aqueous solutions with and without nanoparticle colloidal silica as the continuous phase, and the trisodium citrate (TSC)-rich aqueous solution as the dispersed phase, the water-in-water droplets were effectively prepared through a T-junction microchannel with an internal capillary. The process of droplet generation involves three distinct stages: slow necking, fast necking, and pinch-off. The nanoparticle-stabilized droplets exhibit a slower necking rate in the slow necking stage compared with conventional droplets, and the dimensionless neck width varies linearly with dimensionless time. In the fast necking stage, the adsorption of particles on the droplet surface causes the nanoparticle-stabilized droplets to undergo more difficult interfacial deformation, which further slows down the necking rate. The dimensionless neck width and the dimensionless time have a power-law relationship in the fast necking and pinch-off stages. In general, the droplets stabilized by nanoparticles show a longer formation period and a larger droplet size.