Drop impact on elastic superhydrophobic films: From pancake bouncing to saucer bouncing

Abstract

Realizing a short contact between water drops and surfaces has become a research focus owing to its promising application prospect in anti-icing. Here, we developed an elastic superhydrophobic film with a water contact angle of 166.6°±1.6° and roll-off angle of 2.0°±0.8° to largely reduce the contact time of an impinging drop. The thin films with different strains and after different cycles with a 50% strain could still maintain its low-adhesion superhydrophobicity, demonstrating its excellent adaptability and durability to deal with deformation. It was also found that there was a step-like reduction of the contact time with Weber number We, showing the pancake and saucer bouncing at intermediate and high We, respectively. In comparison with the conventional symmetric bouncing (at low We), the higher elasticity of the film caused by the drop impact contributed to the large contact time reduction for the pancake and saucer bouncing phenomenon.