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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 68: Hydrogels and Microgels II

CPP 68.11: Vortrag

Freitag, 24. März 2017, 13:00–13:15, ZEU 260

Spontaneous jumping and long-lasting bouncing of solid Leidenfrost drops — •Doris Vollmer, Maxime Paven, Tadashi Kajiya, Hans-Jürgen Butt, and Jonathan Pham — MPI for Polymer Research, Mainz

The impact and rebound of liquid drops on hot, solid surfaces is of practical importance in industrial processes, such as thermal coating and spray cooling. The impact of solid spheres is also a commonly encountered event in ball milling, powder processing, and everyday activities, such as ball sports. Liquid drop and solid ball impacts are distinct from each other in terms of their mechanics. Here, we show that hydrogels display unique characteristics of both solids and liquids when heated above the Leidenfrost temperature. Using high speed video microscopy, we demonstrate that millimetric hydrogel drops jump from a hydrophilic surface upon heating and continue to bounce several times with increasing height. While elasticity dominates the mechanics of contact, evaporation supports long-lasting bouncing. This interplay between elastic and liquid properties results in intriguing dynamics, which is reflected in spontaneous jumping, long-lasting bouncing, trampolining, and the shortest contact times ever observed for water-like systems.