Abstract
The contact between liquid drops and hot solid surfaces is of practical importance for industrial processes, such as thermal spraying and spray cooling. The contact and bouncing of solid spheres is also an important event encountered in ball milling, powder processing, and everyday activities, such as ball sports. Using high speed video microscopy, we demonstrate that hydrogel drops, initially at rest on a surface, spontaneously jump upon rapid heating and continue to bounce with increasing amplitudes. Jumping is governed by the surface wettability, surface temperature, hydrogel elasticity, and adhesion. A combination of low-adhesion impact behavior and fast water vapor formation supports continuous bouncing and trampolining. Our results illustrate how the interplay between solid and liquid characteristics of hydrogels results in intriguing dynamics, as reflected by spontaneous jumping, bouncing, trampolining, and extremely short contact times.
Highlights
The contact between liquid drops and hot solid surfaces is of practical importance for industrial processes, such as thermal spraying and spray cooling
By varying wettability of the surface and modulus of the hydrogel, we show that spontaneous jumping is most favorable when the surface is hydrophilic and the hydrogel-surface adhesion is low
Subsequent bouncing and trampolining is governed by hydrogel drop elasticity and fast water vaporization above the Leidenfrost temperature while very short contact times are observed below the Leidenfrost temperature
Summary
The contact between liquid drops and hot solid surfaces is of practical importance for industrial processes, such as thermal spraying and spray cooling. Our results illustrate how the interplay between solid and liquid characteristics of hydrogels results in intriguing dynamics, as reflected by spontaneous jumping, bouncing, trampolining, and extremely short contact times. On the other hand, is characterized by drops rebounding from a surface with a restitution coefficient equal to or below one Upon this background pressure reduction, jumping, bouncing and trampolining are driven by vapor pressure buildup within texture of the superhydrophobic surface under the drop. The hydrogels, initially at rest, spontaneously jump from a rapidly heated surface and subsequently bounce and trampoline as many as 100 times. Subsequent bouncing and trampolining is governed by hydrogel drop elasticity and fast water vaporization above the Leidenfrost temperature while very short contact times are observed below the Leidenfrost temperature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
