Recently, there has been much interest in using lubricated surfaces to achieve extreme liquid repellency: a foreign droplet immiscible with the underlying lubricant layer was shown to slide off at a small tilt angle <5°. This behaviour was hypothesized to arise from a thin lubricant overlayer film sandwiched between the droplet and solid substrate, but this has not been observed experimentally. Here, using thin-film interference, we are able to visualize the intercalated film under both static and dynamic conditions. We further demonstrate that for a moving droplet, the film thickness follows the Landau–Levich–Derjaguin law. The droplet is therefore oleoplaning—akin to tyres hydroplaning on a wet road—with minimal dissipative force and no contact line pinning. The techniques and insights presented in this study will inform future work on the fundamentals of wetting for lubricated surfaces and enable their rational design.

中文翻译：

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润滑表面上的油滑液滴

近来，人们非常关注使用润滑表面来实现极高的拒液性：与下层润滑层不混溶的外来液滴显示出以小于5°的小倾斜角滑落。据推测，此行为是由夹在液滴和固体基材之间的薄润滑剂覆盖层薄膜引起的，但是尚未通过实验观察到。在这里，使用薄膜干涉，我们可以在静态和动态条件下可视化插入的薄膜。我们进一步证明，对于运动的液滴，膜的厚度遵循Landau–Levich–Derjaguin定律。因此，油滴滑油（类似于在湿滑路面上的轮胎滑油），耗散力最小，没有接触线钉扎现象。