The bouncing of droplets on surfaces features the short-time droplet-surface contact, benefiting numerous applications, including self-cleaning, anti-icing, heat transfer control, and so on. Recent studies reported that increasing liquid viscosity inhibits droplet bouncing on nonwetting solid surfaces because of increasing viscous dissipation within the droplet, leading to a divergent contact time when the droplet viscosity is beyond a critical value that is two orders of magnitude higher than that of water. Here, we show that the bouncing of high-viscosity droplets can be promoted when the nonwetting solid surface is replaced by a curved soap film. The contact time of droplets bouncing on curved soap films is found to be almost independent of the droplet viscosity in the high-viscosity regime. It is shown that more than $50\%$ of the initial energy is stored as the surface energy of the soap film during the spreading period, proving the essential role of the deformation of the soap film on the bouncing dynamics. The bouncing promotion mechanism is elucidated by a spring-mass-damper system in which the viscous droplet and the curved soap film are modeled in analogy with a damper and a spring connected in series.

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• Drop & bubble phenomena
• Drop interactions
• Drops & bubbles
• Viscosity