  The bursting of bubbles at an air/liquid interface is a familiar occurrence
important to foam stability, cell cultures in bioreactors and mass transfer
between the sea and atmosphere. Here we document the hitherto unreported
formation and dispersal into the water column of submicrometre oil droplets
following bubble bursting at a compound air/oil/water-with-surfactant
interface. We show that dispersal results from the detachment of an oil spray
from the bottom of the bubble towards water during bubble collapse. We provide
evidence that droplet size is selected by physicochemical interactions between
oil molecules and the surfactants rather than by hydrodynamic effects. We
illustrate the unrecognized role that this dispersal mechanism may play in the
fate of the sea surface micro-layer and of pollutant spills by dispersing
petroleum in the water column. Finally, our system provides an energy-efficient
route, with potential upscalability and wide applicability, for applications in
drug delivery, food production and material science, which we demonstrate by
producing polymeric nanoparticles.

Fluid Dynamics;Materials Science;Atmospheric and Oceanic Physics