School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; Department of Mechanical Engineering, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China.
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
J Colloid Interface Sci. 2023 Sep;645:12-21. doi: 10.1016/j.jcis.2023.04.077. Epub 2023 Apr 25.
For an evaporating nanofluid droplet that contains a bubble inside, we suspect the bubble boundary remains pinned during evaporation whereas the droplet perimeter recedes. Thus, the dry-out patterns are mainly determined by the presence of the bubble and their morphology can be tuned by the size and location of the added bubble.
Bubbles with varying base diameters and lifetimes are added into evaporating droplets that contain nanoparticles with different types, sizes, concentrations, shapes, and wettability. The geometric dimensions of the dry-out patterns are measured.
For a droplet containing a long-lifetime bubble, a complete ring-like deposit forms, and its diameter and thickness increases and decreases with the bubble base diameter, respectively. The ring completeness, i.e., the ratio of actual ring length to its imaginary perimeter, decreases with the decrease in bubble lifetime. The pinning of droplet receding contact line by particles near the bubble perimeter has been found to be the key factor leading to ring-like deposits. This study introduces a strategy of producing ring-like deposit and allows a control of the ring morphology in a simple, cheap, and impurity-free fashion, which is applicable to various applications associated with evaporative self-assembly.
对于含有内部气泡的蒸发纳米流体液滴，我们怀疑气泡边界在蒸发过程中保持固定，而液滴周边则后退。因此，干涸模式主要由气泡的存在决定，并且可以通过添加气泡的大小和位置来调整其形态。
将具有不同基底直径和寿命的气泡添加到含有不同类型、大小、浓度、形状和润湿性的纳米颗粒的蒸发液滴中。测量干涸模式的几何尺寸。
对于含有长寿命气泡的液滴，会形成完整的环状沉积物，其直径和厚度分别随气泡基底直径的增加和减小而增加和减小。环状沉积物的完整性，即实际环状长度与其假想周长的比值，随气泡寿命的降低而降低。在气泡周边附近的颗粒对液滴后退接触线的固定被发现是导致环状沉积物的关键因素。本研究提出了一种产生环状沉积物的策略，并以简单、廉价和无污染的方式允许控制环状形态，适用于与蒸发自组装相关的各种应用。
