Department of Mechanical Engineering, Indian Institute of Science, Bangalore, 560012, India.
Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
Sci Rep. 2017 Aug 9;7(1):7708. doi: 10.1038/s41598-017-08126-3.
Tiny concentrations of suspended particles may alter the behavior of an evaporating droplet remarkably, leading to partially viscous and partially elastic dynamical characteristics. This, in turn, may lead to some striking mechanical instabilities, such as buckling and rupture. Here, we report certain non-trivial implications of the consequent morpho-dynamics (macro to nano scales), when such an evaporating droplet is encapsulated in a confined environment. Compared to unconfined scenario, we report non-intuitive suppression of rupturing beyond a critical confinement. We attribute this to confinement-induced dramatic alteration in the evaporating flux, leading to distinctive spatio-temporal characteristics of the internal flow leading to preferential particle transport and subsequent morphological transitions. We present a regime map quantifying buckling-non buckling pathways. These results may turn out to be of profound importance towards achieving desired morphological features of a colloidal droplet, by aptly tuning the confinement space, initial particle concentration, as well as the initial droplet volume.
微小浓度的悬浮颗粒可能会显著改变蒸发液滴的行为，导致部分粘性和部分弹性动力学特性。这反过来又可能导致一些显著的力学不稳定性，例如屈曲和破裂。在这里，我们报告了当这种蒸发液滴被封装在受限环境中时，随之而来的形态动力学（从宏观到纳米尺度）的某些重要含义。与无约束情况相比，我们报告了在临界约束之外，破裂的非直观抑制。我们将其归因于约束引起的蒸发通量的剧烈变化，导致内部流动的独特时空特征，从而导致优先的颗粒输运和随后的形态转变。我们提出了一个定量描述屈曲-非屈曲途径的规则图。这些结果对于通过适当调整约束空间、初始颗粒浓度以及初始液滴体积来实现胶体液滴的所需形态特征，可能具有深远的重要意义。
