Wang Shixian, Lin Dongdong, Francisco Joseph S, Zeng Xiao Cheng, Gao Yurui
Laboratory of Theoretical and Computational Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Am Chem Soc. 2024 Oct 23;146(42):28748-28756. doi: 10.1021/jacs.4c07473. Epub 2024 Oct 8.
Understanding droplet wetting on surfaces has broad implications for surface science and engineering. Here, we report a joint theoretical/experimental study of the topological wetting states of water droplets on chemically heterogeneous closed-loop and planar surfaces. Interestingly, we provide both simulation and experimental evidence of biloop or even multiloop transition wetting states of water droplets. Specifically, in our molecular dynamics simulations, we designed surfaces patterned with alternating closed-loop superhydrophilic and hydrophobic nanobands. On these surfaces, we find that the contact shape and contact angle of water nanodroplets can be tailored by changing the shape of the nanobands. Overall, the contact angle of the droplets is dependent on the initial location of the water droplet, the interaction between the water molecules and hydrophobic particles, and the width of the superhydrophilic and hydrophobic nanobands. The wetting-state transition dynamics is also dependent on the nanoband shape. In the biloop or multiloop transition wetting states, the three-phase contact line is not limited to only one loop nanoband but can be located at two or more distinct loops. Guided by the simulation results, the corresponding experiments confirmed the presence of topological wetting states and multiloop wetting states on planar chemically heterogeneous surfaces with closed-loop microbands. Importantly, we provide an explanation of the mechanism of the topological wetting state formation and transition. Our study facilitates a deeper understanding of the droplet-surface interactions and offers an alternative way to tune the droplet shape and contact angle on planar surfaces by engineering chemically heterogeneous surface textures.
理解液滴在表面上的润湿性对表面科学与工程具有广泛的意义。在此，我们报告了一项关于水滴在化学异质闭环和平面表面上拓扑润湿性状态的理论/实验联合研究。有趣的是，我们提供了水滴双环甚至多环转变润湿性状态的模拟和实验证据。具体而言，在我们的分子动力学模拟中，我们设计了由交替的闭环超亲水和疏水纳米带图案化的表面。在这些表面上，我们发现水纳米滴的接触形状和接触角可以通过改变纳米带的形状来调整。总体而言，液滴的接触角取决于水滴的初始位置、水分子与疏水颗粒之间的相互作用以及超亲水和疏水纳米带的宽度。润湿性状态转变动力学也取决于纳米带的形状。在双环或多环转变润湿性状态下，三相接触线不仅限于一个环形纳米带，而是可以位于两个或更多不同的环处。在模拟结果的指导下，相应的实验证实了在具有闭环微带的平面化学异质表面上存在拓扑润湿性状态和多环润湿性状态。重要的是，我们对拓扑润湿性状态的形成和转变机制进行了解释。我们的研究有助于更深入地理解液滴与表面之间的相互作用，并提供了一种通过设计化学异质表面纹理来调整平面上液滴形状和接触角的替代方法。
