Fig. 4: Mechanism of defoaming by bubble bursting.

a Temporal analysis of bubble rupture using high-speed cameras. The approach velocities (bubble rise) varied between 1 and 25 cm s⁻¹ using different release distances from the superamphiphobic surface. Liquids: water, ethanol–water mixture, and beer. Scale bar: 500 µm. b Spatial analysis of bubble rupture using holographic microscopy. The film height, \(h\left(t\right)=\delta h\left(t\right)+{h}_{c}\), of a captive bubble during a slow controlled approach (5 µm s⁻¹). The thickness of spontaneous rupture, \({h}_{c}\) is within the order of 100 nm for beer (orange circles) due to hydrophobic interactions. Inset: Phase maps monitoring the variation of film height. Height variation between dark and white lines is ≈ 300 nm. Scale bar: 100 µm. Schematics: c Approach of a bubble encountering a superamphiphobic surface. d Bulk drainage of liquid between the bubble and the nanoprotrusions. e Film thinning by interfacial and hydrodynamic forces. \({h}_{c}\), is the critical height of spontaneous rupture, taking into account the surface-penetrated depth determined using interference microscopy (\(\triangle h\), Supplementary Fig. 7). f Momentary film stabilization due to repulsive interactions. g Hydrophobic interactions induce spontaneous rupture of a sufficiently thin film. Schematics are not to scale.