Pancake bouncing on superhydrophobic surfaces

TY - JOUR

T1 - Pancake bouncing on superhydrophobic surfaces

AU - Liu, Yahua

AU - Moevius, Lisa

AU - Xu, Xinpeng

AU - Qian, Tiezheng

AU - Yeomans, Julia M.

AU - Wang, Zuankai

N1 - Funding Information: We are grateful for support from the Hong Kong Early Career Scheme Grant (No. 125312), National Natural Science Foundation of China (No. 51276152), CityU9/CRF/13G, the National Basic Research Program of China (2012CB933302) and Center of Super-Diamond and Advanced Films (COSDAF) at CityU to Z.W., ERC Advanced Grant, MiCE, to J.M.Y., and RGC Grant 603510 to T.Q. Experimental assistance was provided by Y. Liu and L. Xu. The authors gratefully thank D. Quéré for many useful discussions.

PY - 2014/7

Y1 - 2014/7

N2 - Engineering surfaces that promote rapid drop detachment1,2 is of importance to a wide range of applications including anti-icing3-5, dropwise condensation6 and self-cleaning7-9. Here we show how superhydrophobic surfaces patterned with lattices of submillimetre-scale posts decorated with nanotextures can generate a counter-intuitive bouncing regime: drops spread on impact and then leave the surface in a flattened, pancake shape without retracting. This allows a fourfold reduction in contact time compared with conventional complete rebound1,10-13. We demonstrate that the pancake bouncing results from the rectification of capillary energy stored in the penetrated liquid into upward motion adequate to lift the drop. Moreover, the timescales for lateral drop spreading over the surface and for vertical motion must be comparable. In particular, by designing surfaces with tapered micro/nanotextures that behave as harmonic springs, the timescales become independent of the impact velocity, allowing the occurrence of pancake bouncing and rapid drop detachment over a wide range of impact velocities.

AB - Engineering surfaces that promote rapid drop detachment1,2 is of importance to a wide range of applications including anti-icing3-5, dropwise condensation6 and self-cleaning7-9. Here we show how superhydrophobic surfaces patterned with lattices of submillimetre-scale posts decorated with nanotextures can generate a counter-intuitive bouncing regime: drops spread on impact and then leave the surface in a flattened, pancake shape without retracting. This allows a fourfold reduction in contact time compared with conventional complete rebound1,10-13. We demonstrate that the pancake bouncing results from the rectification of capillary energy stored in the penetrated liquid into upward motion adequate to lift the drop. Moreover, the timescales for lateral drop spreading over the surface and for vertical motion must be comparable. In particular, by designing surfaces with tapered micro/nanotextures that behave as harmonic springs, the timescales become independent of the impact velocity, allowing the occurrence of pancake bouncing and rapid drop detachment over a wide range of impact velocities.

UR - http://www.scopus.com/inward/record.url?scp=84903754966&partnerID=8YFLogxK

U2 - 10.1038/nphys2980

DO - 10.1038/nphys2980

M3 - 文章

AN - SCOPUS:84903754966

SN - 1745-2473

VL - 10

SP - 515

EP - 519

JO - Nature Physics

JF - Nature Physics

IS - 7

ER -