疏水性表面上负载软胶体液滴的三线动力学。

Triple-line dynamics of a soft colloid-laden drop on a hydrophobic surface.

作者信息

Jose Merin, Singh Rajesh, Satapathy Dillip K

机构信息

Department of Physics, Indian Institute of Technology Madras, Chennai - 600036, India.

出版信息

Soft Matter. 2023 Mar 1;19(9):1803-1812. doi: 10.1039/d2sm01486f.

Abstract

Evaporation of fluid from a pinned drop placed on solid surface proceeds constant contact radius (CCR) mode, with a continuous reduction in the contact angle. The reduction of contact angle leads to an imbalance of interfacial tensions at the three-phase contact line. When the unbalanced force is sufficiently strong, the drop slips from the pinned contact line and slides inward. Depinning of the drop alters the mode of evaporation to constant contact angle (CCA) mode till it repins onto the surface. The change in evaporation mode from CCR to CCA is usually achieved by tuning the pinning energy barrier by controlling the surface properties of the substrate. Here, we demonstrate that the evaporation mode can be controlled by solely tailoring the surface tension of the drop, which is achieved in microgel particle-laden sessile drops that show spontaneous adsorption of microgels to the air/water interface, leading to a decrease in the interfacial tension. We show that droplets containing a sufficient number of microgels evaporate predominantly in CCR mode even on a hydrophobic surface, and the contact line remains pinned throughout the evaporation of the drop. Interestingly, the contact line dynamics can be controlled by tuning the softness of the microgels and the particle concentration in the drops.

摘要

置于固体表面的固定液滴的流体蒸发以恒定接触半径(CCR)模式进行,接触角持续减小。接触角的减小会导致三相接触线处的界面张力失衡。当不平衡力足够强时,液滴会从固定的接触线滑落并向内滑动。液滴的脱钉会使蒸发模式转变为恒定接触角(CCA)模式,直至其重新固定在表面上。从CCR到CCA的蒸发模式变化通常是通过控制基底的表面性质来调整钉扎能垒实现的。在此,我们证明仅通过调整液滴的表面张力就可以控制蒸发模式,这在负载微凝胶颗粒的固着液滴中得以实现,这些液滴表现出微凝胶自发吸附到空气/水界面,导致界面张力降低。我们表明,即使在疏水表面上,含有足够数量微凝胶的液滴也主要以CCR模式蒸发,并且在液滴蒸发的整个过程中接触线保持固定。有趣的是,接触线动力学可以通过调整微凝胶的柔软度和液滴中的颗粒浓度来控制。

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