Particle-Stabilized Water Droplets that Sprout Millimeter-Scale Tubes

Millimeter‐scale tubes are observed to sprout from water droplets injected into a bath of toluene containing ethanol and silica colloids. This phenomenon requires that first a membrane is formed by the colloids which self‐assemble at the droplet interface, and second, that the ethanol preferentially partitions into the aqueous phase leading to an internal over‐pressure. Tube growth, eruption, and shuffling droplets are subsequently observed, depending on the concentration of ethanol and colloids selected. This work opens many possibilities in the field of biomimetic droplets for fundamental studies of artificial growth at the microscale and for emulsion‐related applications. Sprouting droplets: With increasing time, tubes are observed to sprout from water droplets with rigid membranes formed from colloidal particles trapped on the liquid–liquid interface. This is driven by an internal over‐pressure which arises as a result of a minority constituent on the outside of the droplet that preferentially partitions into the water inside the membrane.