Spreading Dynamics of Water Droplets on a Completely Wetting Surface
Spreading Dynamics of Water Droplets on a Completely Wetting Surface
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DOI：
10.1021/acs.jpcc.0c05167
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发表时间：
2020-09-17
影响因子：
3.7
通讯作者：
Tsige, Mesfin
中科院分区：
文献类型：
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作者：
Bekele, Selemon;Evans, Oliver G.;Tsige, Mesfin
首次用原子分子动力学模拟了不同大小的水滴在完全润湿表面上的扩散，其中扩散的动力学由基质和水分子之间的氢键控制。观察到的扩散的特征是，液滴的大部分散布在高密度的单分子水层上，水滴放置在表面后几十皮秒内形成。单层膜呈现出两种不同的扩散规律，每一种扩散规律在时间上都遵循不同的指数规律，且后期比Tanner定律所预测的要快。液滴的主体部分最初以增加的半径在单层上扩散，直到特征时间t*。在t*之后，它在保持恒定接触角的同时收缩，有趣的是，半径可以用基于流体力学理论的第一原理模型很好地描述。总体而言，模拟结果与最近的实验数据定性一致。
The spreading of water droplets of varying sizes on a completely wetting surface where the kinetics of spreading are controlled by hydrogen bonding between substrate and water molecules is modeled for the first time using atomistic molecular dynamics simulations. The spreading observed is characterized by the bulk part of a droplet spreading over a high density monolayer of water that forms within tens of picoseconds after the droplet is placed on the surface. The monolayer exhibits two spreading regimes, each following a power law in time with different exponents, and the late stage is faster than that predicted by Tanner's law. The bulk part of the droplet initially spreads over the monolayer with increasing radius until a characteristic time t*. Beyond t*, it shrinks while maintaining a constant contact angle and, interestingly, the radius is described well with a first-principles model based on hydrodynamic theory. Overall, the simulation results qualitatively agree with recent experimental data.