Imbibition and evaporation of droplets of colloidal suspensions on permeable substrates
Imbibition and evaporation of droplets of colloidal suspensions on permeable substrates
复制标题
胶体悬浮液液滴在可渗透基质上的吸入和蒸发
DOI：
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发表时间：
2019
影响因子：
2.7
通讯作者：
Satish Kumar
中科院分区：
文献类型：
--
作者：
Truong Pham;Satish Kumar
最近的实验表明，基底渗透性可以抑制蒸发液滴留下的凝固模式，促进更均匀的溶质沉积。受这些观察结果的启发，我们开发了一个基于润滑理论的模型来描述胶体悬浮液液滴在可渗透基质上的吸胀和蒸发。该模型由一个一维偏微分方程系统组成，该系统考虑了液滴形状和胶体颗粒深度平均浓度的变化。我们还结合了前驱体膜、分离压力和衬底形貌来控制液滴的接触线运动。溶剂蒸发是用众所周知的单侧模型来描述的，并且假定基材对溶剂的吸积只取决于液体侧的超压力。用有限差分法求解控制方程。结果表明，溶剂蒸发和溶剂吸胀对最终颗粒沉积模式有相同的定性影响。对于衬底光滑的情况，我们发现增加吸胀或蒸发会导致从锥形沉积模式转变为环状沉积模式。在衬底粗糙的情况下，液滴接触线被钉住在衬底上的缺陷处，钉钉-脱钉转变导致实验中经常观察到的“靶心”沉积模式。最后，我们还发现，在光滑和粗糙的基底上，颗粒吸附可以促进更均匀的颗粒沉积模式，而溶剂吸胀可以通过诱导更多的颗粒吸附来间接抑制咖啡环模式。1未出版。国际科学技术研究所不对论文或出版物中所载的陈述或意见负责。
Recent experiments have shown that substrate permeability can suppress the coffeering pattern that is often left by evaporating droplets and promote more uniform solute deposition. Motivated by these observations, we have developed a lubrication-theorybased model to describe imbibition and evaporation of droplets of colloidal suspensions on permeable substrates. The model consists of a system of one-dimensional partial differential equations accounting for the changing droplet shape and depth-averaged concentration of colloidal particles. We also incorporate a precursor film, disjoining pressure, and substrate topography to control contact-line motion of the droplet. Solvent evaporation is described using the well-known one-sided model, and imbibition of solvent by the substrate is assumed to only depend on the excess pressure on the liquid side. The governing equations are solved with finite-difference methods. Our results reveal that solvent evaporation and solvent imbibition have the same qualitative effect on the final particle deposition pattern. For the case where the substrate is smooth, we find that increasing imbibition or evaporation leads to a transition from a cone-shaped deposition pattern to a ring-shaped deposition pattern. For the case where the substrate is rough, the droplet contact line is pinned at a defect on the substrate, and the pinning-depinning transition leads to the ``bullseye'' deposition pattern often observed in experiments. Finally, we also find that particle adsorption onto the substrate can promote more uniform particle deposition patterns for both smooth and rough substrates, and solvent imbibition can indirectly suppress the coffee-ring pattern by inducing more particle adsorption. 1 Unpublished. ISCST shall not be responsible for statements or opinions contained in papers or printed in its publications.
DOI：
10.1021/la400224a
发表时间：
2013-07-02
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
--
作者：
Wen JT;Ho CM;Lillehoj PB
通讯作者：
Lillehoj PB