Ratschow Aaron D, Bauer Lisa S, Bista Pravash, Weber Stefan A L, Butt Hans-Jürgen, Hardt Steffen
Institute for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Straße 10, D-64287 Darmstadt, Germany.
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Phys Rev Lett. 2024 May 31;132(22):224002. doi: 10.1103/PhysRevLett.132.224002.
Charge separation behind moving water drops occurs in nature and technology. Yet, the physical mechanism has remained obscure, as charge deposition is energetically unfavorable. Here, we analyze how a part of the electric double layer charge remains on the dewetted surface. At the contact line, the chemical equilibrium of bound surface charge and diffuse charge in the liquid is influenced by the contact angle and fluid flow. We summarize the mechanism in an analytical model that compares well with experiments and simulations. It correctly predicts that charge separation increases with increasing contact angle and decreases with increasing velocity.
移动水滴背后的电荷分离现象在自然界和技术领域都有发生。然而，由于电荷沉积在能量上是不利的，其物理机制一直不明朗。在此，我们分析了电双层电荷的一部分如何保留在去湿表面上。在接触线处，液体中结合表面电荷和扩散电荷的化学平衡受接触角和流体流动的影响。我们在一个分析模型中总结了该机制，该模型与实验和模拟结果吻合良好。它正确地预测出电荷分离随接触角的增大而增加，随速度的增大而减小。
