Measurements of contact angles are conventionally used to describe the wetting behavior of nanoscopic liquid droplets on a flat substrate, where the dissimilar molecular interface is vague. Considering this issue, we performed an atomistic simulation of the spherical nano-droplets of pure and ion-water on a bare solid substrate to determine the relationship between the contact angle and the boundary position residing at the solid–liquid interface. In this exploration, the existence of the correlation between the contact angle and the associated boundaries is observed using classical Young’s equation. Our study reveals that the effects of the variable wettability and boundary positions have a significant impact on the contact angle. In addition, we investigate the contact angle based on boundary positions for different ion-water nano-droplets with varying ion concentrations. Interestingly, the contact angles of pure and ion-water droplets are almost identical in a specific boundary position for both varying wettability and ion concentrations. Finally, we compare the estimated contact angle for different boundary positions with the solid substrate experimental contact angle. Atomistic simulations indicate that the interfacial boundary concept for measuring contact angle using classical Young’s equation gives a certain convergence to experimental evaluation.

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中文翻译：

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不同分子界面和离子浓度对纳米液滴润湿特性的影响

接触角的测量通常用于描述纳米级液滴在平坦基板上的润湿行为，其中不同的分子界面是模糊的。考虑到这个问题，我们在裸露的固体基底上对纯水和离子水的球形纳米液滴进行了原子模拟，以确定接触角与固液界面处的边界位置之间的关系。在本次探索中，使用经典杨氏方程观察到接触角和相关边界之间存在相关性。我们的研究表明，可变润湿性和边界位置的影响对接触角有显着影响。此外，我们根据不同离子浓度的不同离子-水纳米液滴的边界位置研究了接触角。有趣的是，对于不同的润湿性和离子浓度，纯水滴和离子水滴的接触角在特定边界位置几乎相同。最后，我们将不同边界位置的估计接触角与固体基板实验接触角进行比较。原子模拟表明，使用经典杨氏方程测量接触角的界面边界概念为实验评估提供了一定的收敛性。我们将不同边界位置的估计接触角与固体基板实验接触角进行比较。原子模拟表明，使用经典杨氏方程测量接触角的界面边界概念为实验评估提供了一定的收敛性。我们将不同边界位置的估计接触角与固体基板实验接触角进行比较。原子模拟表明，使用经典杨氏方程测量接触角的界面边界概念为实验评估提供了一定的收敛性。

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