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中文核心期刊

溶质引起的自由液面Marangoni铺展研究综述

REVIEW OF SOLUTAL MARANGONI SPREADING ON FREE SURFACE

  • 摘要: Marangoni流动是一种由表面张力梯度驱动的界面铺展和液体内部的对流. 其中, 表面张力梯度可以通过温度或溶质的不均匀分布来调控. 由溶质引起的Marangoni铺展在呼吸道药物输送等生物医学领域、复杂结构颗粒制备和镀膜等先进制造领域有着重要应用. 溶质分子的诸多物理化学过程都会对Marangoni铺展的动力学产生影响, 例如分子在界面上的输运、液滴与基底之间的物质交换、挥发性溶质在自由液面的蒸发, 都会对表面张力梯度起到动态的调控作用. 同时, 在铺展液体特殊的本构性质和Marangoni铺展提供的强剪切率的共同作用下, 流体会呈现一系列复杂而有趣的现象. 文章着重介绍近年来领域内开展的由溶质引起的Marangoni铺展, 包括表面活性分子参与的Marangoni铺展, 互混液体界面、复杂流体自由液面的Marangoni铺展, 以及组分差异性蒸发引起的Marangoni铺展, 并阐述它们的演化机制. 最后将列举Marangoni铺展在新兴工业领域中的应用, 为开发借助溶质的本构性质等物理化学性质实现液体驱动的低能耗器件和生产工艺提供参考.

     

    Abstract: Marangoni flow is the interfacial spreading driven by an uneven distribution of surface tension. While it consists a shear flow at the interface, it may also induce severe interfacial deformation in case of spreading on a thin film, and fluid convection in case of spreading on a thick layer. The surface tension gradient can be modulated by the nonuniform distribution of temperature or of solutes, such as surfactant molecules and components that are miscible with the substrate. Solutal Marangoni spreading has important applications in biomedical fields such as the drug delivery in human airways, as well as in advanced manufacturing fields such as the formation of particles with complex structure and surface coating. Some physicochemical processes of solute molecules can affect the dynamics of Marangoni spreading, for instance, the transport of molecules at the interface, the mass exchange between the droplet and the substrate, and the evaporation of volatile solutes at the free liquid surface, which modulate the surface tension gradient instantaneously. In addition, under the combined effects of the rheological properties of the liquids and the strong shear rate induced by Marangoni spreading, the fluids may exhibit a series of complex and interesting phenomena. Based on the review article on solutal Marangoni spreading published by Matar and Craster in 2009, this review summarizes works reported on solutal Marangoni spreading in recent years, including surfactant-assisted spreading with modulated solubility, Marangoni spreading at interface of miscible liquids, and on free surfaces of complex fluids, as well as Marangoni spreading due to selective evaporation of one component in a fluid mixture. Phenomena will be presented and the mechanisms will be discussed. Finally, this review will enumerate the applications of Marangoni spreading in emerging industrial fields to provide references for developing low-energy devices and production processes that utilize the physicochemical properties of liquids.

     

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