Wetting of liquid droplets on passive surfaces is ubiquitous in our daily lives, and the governing physical laws are well understood. When surfaces become active, however, the governing laws of wetting remain elusive. Here, we propose chemically active wetting as a class of active systems where the surface is active due to a binding process that is maintained away from equilibrium. We derive the corresponding nonequilibrium thermodynamic theory and show that active binding fundamentally changes the wetting behavior, leading to steady, nonequilibrium states with droplet shapes reminiscent of a pancake or a mushroom. The origin of such anomalous shapes can be explained by mapping to electrostatics, where pairs of binding sinks and sources correspond to electrostatic dipoles along the triple line. This is an example of a more general analogy, where localized chemical activity gives rise to a multipole field of the chemical potential. The underlying physics is relevant for cells, where droplet-forming proteins can bind to membranes accompanied by the turnover of biological fuels.

中文翻译：

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化学活性润湿


液滴在被动表面上的润湿在我们的日常生活中无处不在，并且控制物理定律已得到充分理解。然而，当表面变得活跃时，润湿的控制定律仍然难以捉摸。在这里，我们提出化学活性润湿作为一类活性系统，其中表面由于保持不平衡的结合过程而处于活跃状态。我们推导出了相应的非平衡热力学理论，并表明主动结合从根本上改变了润湿行为，导致稳定的非平衡状态，液滴形状让人想起煎饼或蘑菇。这种异常形状的起源可以通过映射到静电来解释，其中成对的结合汇和源对应于沿三重线的静电偶极子。这是一个更通用的类比示例，其中局部化学活性产生了化学势的多极场。基础物理学与细胞有关，细胞中形成液滴的蛋白质可以随着生物燃料的周转与膜结合。