论文标题：Spontaneous droplets gyrating via asymmetric self-splitting on heterogeneous surfaces

期刊：Nature Communications

作者：Huizeng Li, Wei Fang, Yanan Li, Qiang Yang, Mingzhu Li, Qunyang Li, Xi-Qiao Feng, Yanlin Song

发表时间：2019/03/05

数字识别码： 10.1038/s41467-019-08919-2

原文链接：http://t.cn/EMvfp2c

微信链接：https://mp.weixin.qq.com/s/47cL82LcVPbJN4_pGe_ahg

《自然-通讯》本周发表的一项研究Spontaneous droplets gyrating via asymmetric self-splitting on heterogeneous surfaces提出了一种表面设计方法，可以让撞击的水滴在回弹时发生旋转，且转速超过7300 rpm（每分钟转数）。该研究结果在水能采集、自清洁和防冰冻方面或具有应用价值。

图1：水滴撞击动力学。图源：Li等

水滴撞击表面后的结果（水滴弹回或飞溅）取决于固体表面的结构和化学性质。但是，由于水滴具有可变形性，且撞击水滴与固体发生相互作用的速度极快，操控这种行为存在一定难度。

图2：液滴旋转的机械分析。图源：Li等

中国科学院化学研究所的宋延林、清华大学的冯西桥和同事介绍了一种化学图案化方法，在高粘附力螺旋周围设计疏水（对水具有排斥性）低粘附区域。当水滴撞击表面后，这些图案会引发非轴对称钉扎力（一种绕轴的非对称力），让水滴在反弹时发生旋转。

图3：一滴染料在粘附力分布不均的平面反弹后旋转。来源：宋延林

图4：一滴纳米颗粒分散体在粘附力分布不均的平面反弹后旋转。来源：宋延林

作者认为，观察到的过程为实现液体运动的精确操控提供了新的可能途径。

摘要：Droplet impacting and bouncing off solid surface plays a vital role in various biological/physiological processes and engineering applications. However, due to a lack of accurate control of force transmission, the maneuver of the droplet movement and energy conversion is rather primitive. Here we show that the translational motion of an impacting droplet can be converted to gyration, with a maximum rotational speed exceeding 7300 revolutions per minute, through heterogeneous surface wettability regulation. The gyration behavior is enabled by the synergetic effect of the asymmetric pinning forces originated from surface heterogeneity and the excess surface energy of the spreading droplet after impact. The findings open a promising avenue for delicate control of liquid motion as well as actuating of solids.

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期刊介绍：Nature Communications (https://www.nature.com/ncomms/) is an open access journal that publishes high-quality research from all areas of the natural sciences. Papers published by the journal represent important advances of significance to specialists within each field.

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（来源：科学网）