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中国物理学会期刊

等离子体辅助构筑非对称润湿性Janus纤维膜的液滴输运行为数值模拟

CSTR: 32037.14.aps.74.20250908

Numerical simulation of droplet transport behavior in plasma-assisted fabricated asymmetric wettability Janus fiber membranes

CSTR: 32037.14.aps.74.20250908
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  • 非对称润湿性Janus纤维膜凭借其两侧显著的润湿性差异, 在与液体相互作用时展现出诸多独特性能, 因此在微流控和生物医学等领域具有广阔的应用前景. 液滴定向输运作为Janus纤维膜的关键功能之一, 其输运机制与调控规律对于实际应用至关重要. 然而, 目前对于润湿性梯度及孔隙结构如何调控液滴定向输运行为的研究尚不充分. 本文建立了两相流-相场模型, 结合等离子体辅助构筑的Janus纤维膜液滴输运实验, 验证了模型的可靠性; 在此基础上, 系统研究了液滴在膜内的定向输运行为. 研究表明, 液滴从疏水侧向亲水侧的自发输运由表面自由能梯度、Laplace压差及毛细力协同驱动; 疏水层厚度、亲水层厚度、润湿性梯度和孔隙结构是调控输运效率的关键因素. 相较于传统非对称润湿性结构, 具有润湿性梯度的Janus纤维膜可显著提升液滴定向输运速度, 且亲水侧润湿性与输运速度呈显著正相关; 增大孔隙虽能加速液滴输运, 却会导致其在亲水侧的稳态铺展面积减小. 本研究为优化Janus纤维膜结构、实现液滴的高效与精准操控提供了重要理论依据.

     

    The asymmetric wetting Janus fiber membrane exhibits many unique properties when interacting with liquids due to its significant difference in wetting properties on both sides. Therefore, it has broad application prospects in fields such as microfluidics and biomedicine. The directional transport of droplets is one of the key functions of Janus fiber membranes, and its transport mechanism and regulation rules are crucial for practical applications. However, there is currently insufficient research on how wettability gradient and pore structure regulate the directional transport behavior of droplets. In this study, a two-phase flow phase-field model is established, and the reliability of the model is validated through droplet transport experiments conducted on plasma-assisted fabricated Janus fiber membranes. Building on this foundation, the directional transport behavior of droplets within the membrane is systematically investigated. The results show that the spontaneous transport of droplets from hydrophobic side to hydrophilic side is driven by a synergistic effect of surface free energy gradient, Laplace pressure difference, and capillary force. It is found that hydrophobic layer thickness, hydrophilic layer thickness, wettability gradient, and pore structure are key factors in regulating transport efficiency. Compared with traditional structures, Janus fiber membranes with wettability gradients can significantly improve the directional transport speed of droplets, and the wettability of the hydrophilic side shows a significant positive correlation with transport velocity. Although increasing pores can accelerate droplet transport, it simultaneously reduces the steady-state spreading area on the hydrophilic side. This study provides an important theoretical basis for optimizing the Janus fiber membrane structure and achieving efficient and precise fabrication of droplets.

     

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