Heterogeneous substrates with moderate and extreme wettability contrasts were fabricated by comprising of superhydrophobic/hydrophilic and superhydrophobic/extremely hydrophilic surfaces, respectively. The interactions of water droplets impinging on the surfaces with sharp wettability contrasts were investigated experimentally. The impinging droplets that slightly touch the hydrophilic or extremely hydrophilic areas on each substrate exhibit a directional rebounding towards the more wetting surfaces, i.e., hydrophilic or extremely hydrophilic surface. The trajectory and landing distance of the rebounded droplets were tailored by controlling the releasing height of the droplet, wetting contrast across the border, and portion of the droplet touching the more wetting surface of the substrates with wettability contrasts. The landing distance of the droplet increases with the increased releasing height and higher wettability contrast across the border. Increasing the portion of the impinging droplet touching the more wetting surface of the heterogeneous substrates leads to the shorter landing distance of rebounded droplets.

中文翻译：

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具有润湿性对比的表面上的液滴撞击行为

分别由超疏水/亲水和超疏水/极亲水表面组成具有中等和极端润湿性对比的异质基材。通过实验研究了撞击表面的水滴与具有明显润湿性对比的相互作用。轻微接触每个基材上的亲水性或极度亲水性区域的撞击液滴表现出朝向更润湿的表面，即亲水性或极度亲水性表面的定向回弹。回弹液滴的轨迹和着陆距离是通过控制液滴的释放高度、边界上的润湿对比度以及接触具有润湿性对比度的基材更润湿表面的部分来定制的。液滴的着陆距离随着释放高度的增加和边界上润湿性对比度的增加而增加。增加撞击液滴接触异质基底更润湿表面的部分会导致回弹液滴的着陆距离更短。