Evaporation can stabilize a bubble at a free surface without surfactants*

When a bubble arrives at a free surface, we typically expect the film of the bubble cap to thin over some period of time until it ruptures. Traditionally, the drainage of this film has been considered inevitable, and even the addition of surfactants cannot prevent its eventual rupture. Here we present air bubbles at the free surface of liquids which appear to defy traditional drainage rules and can avoid rupture, persisting for hours until dissolution. Using pure, volatile liquids free of any surfactants, we highlight and model a phenomenon in which liquid surrounding the bubble is continuously drawn into the bubble cap, effectively overpowering the drainage effects. We compare our model to data obtained from white light interferometry and thermographic images.