Evolution and Disappearance of Solvent Drops on Miscible Polymer Subphases.
Evolution and Disappearance of Solvent Drops on Miscible Polymer Subphases.
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溶剂滴在可混溶聚合物亚相上的演变和消失。
DOI：
10.1016/j.colsurfa.2018.03.003
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
CarnegieMellonCenterforComplexFluidsEngineering
中科院分区：
文献类型：
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作者：
Stetten,AmyZ;Treece,BradleyW;Corcoran,TimothyE;Garoff,Stephen;Przybycien,ToddM;Tilton,RobertD;CarnegieMellonCenterforComplexFluidsEngineering
传统上，界面被定义为不相容相之间的边界。然而，以前的工作表明，即使两种流体完全相容，它们也会在很长时间内保持可检测到的“有效界面”。在两种流体之间只有一种边界的不同体系中，已经研究了可混相界面。然而，这项工作并没有扩展到放置在混相池顶部的液滴的三相体系。结果表明，这三相体系与非混溶体系符合相同的润湿条件，液滴形状服从增广的Young-Laplace方程。随着时间的推移，可混溶的界面扩散，液滴的形状发生变化。我们将2微升的水滴放在可混溶的聚丙烯酰胺溶液上。液滴被亚相完全润湿，然后在表面下保持可检测到的许多分钟。利用毛细管数可以近似计算出初始有效界面张力约为0.5mN/m 。水和聚丙烯酰胺在所有浓度下都是完全相容的，但从侧面看，液滴仍保持毛细管状。对这一行为的研究对于理解可混溶聚合物相之间的有效界面非常重要，可混溶聚合物相之间的有效界面在自然界中普遍存在。
Traditionally, an interface is defined as a boundary between immiscible phases. However, previous work has shown that even when two fluids are completely miscible, they maintain a detectable “effective interface” for long times. Miscible interfaces have been studied in various systems of two fluids with a single boundary between them. However, this work has not extended to the three-phase system of a fluid droplet placed on top of a miscible pool. We show that these three-phase systems obey the same wetting conditions as immiscible systems, and that their drop shapes obey the Augmented Young-Laplace Equation. Over time, the miscible interface diffuses and the shape of the drop evolves.We place 2-microliter drops of water atop miscible poly(acrylamide) solutions. The drop is completely wetted by the subphase, and then remains detectable beneath the surface for many minutes. An initial effective interfacial tension can be approximated to be on the order of 0.5 mN/m using the capillary number. Water and poly(acrylamide) are completely miscible in all concentrations, and yet, when viewed from the side, the drop maintains a capillary shape. Study of this behavior is important to the understanding of effective interfaces between miscible polymer phases, which are pervasive in nature.