Evaporation-Induced Crystallization of Surfactants in Sessile Multicomponent Droplets

Delayed coalescence of surfactant containing sessile droplets

When two sessile drops of the same liquid touch, they merge into one drop, driven by capillarity. However, the coalescence can be delayed, or even completely stalled for a substantial period of time, when the two drops have different surface tensions, despite being perfectly miscible. A temporary state of non-coalescence arises, during which the drops move on their substrate, only connected by a thin neck between them. Existing literature covers pure liquids and mixtures with low surface activities. In this paper, we focus on the case of large surface activities, using aqueous surfactant solut…

含表面活性剂的固着液滴的聚结

Coalescence of sessile aqueous droplets laden with surfactant

本研究通过大规模分子动力学模拟，揭示了含表面活性剂固着液滴在不同润湿性基底上的聚结机制，发现接触角影响聚结行为，桥接生长遵循2/3幂律，且表面活性剂浓度增加会减缓聚结。

Lifetime of sessile saliva droplets in the context of SARS-CoV-2

Spreading of respiratory diseases, such as COVID-19, from contaminated surfaces is dependent on the drying time of the deposited droplets containing the virus. The evaporation rate depends on environmental conditions, such as ambient temperature and relative humidity and physical properties (e.g., droplet volume, contact angle and composition). The respiratory droplets contain salt (NaCl), protein (mucin), and surfactant (dipalmitoylphosphatidylcholine) in addition to water, which are expected to influence the evaporation in a big way. A diffusion-based theoretical model for estimating the dry…

Evaporation-triggered segregation of sessile binary droplets

Droplet evaporation of multicomponent droplets is essential for various physiochemical applications, e.g. in inkjet printing, spray cooling and microfabrication. In this work, we observe and study phase segregation of an evaporating sessile binary droplet, consisting of a mixture of water and a surfactant-like liquid (1,2-hexanediol). The phase segregation (i.e., demixing) leads to a reduced water evaporation rate of the droplet and eventually the evaporation process ceases due to shielding of the water by the non-volatile 1,2-hexanediol. Visualizations of the flow field by particle image velo…

蒸发中的 sessile 液滴：溶质 Marangoni 效应压倒热 Marangoni 流

Evaporating sessile droplets: solutal Marangoni effects overwhelm thermal Marangoni flow

本研究通过实验和有限元模拟发现，微量表面活性剂导致的溶质 Marangoni 效应可压倒热 Marangoni 效应，使蒸发水滴内流动反转并破坏轴对称性。

Evaporation of dilute sodium dodecyl sulfate droplets on a hydrophobic substrate

Evaporation of surfactant laden sessile droplets is omnipresent in nature and industrial applications such as inkjet printing. Soluble surfactants start to form micelles in an aqueous solution for surfactant concentrations exceeding the critical micelle concentration (CMC). Here, the evaporation of aqueous sodium dodecyl sulfate (SDS) sessile droplets on hydrophobic surfaces were experimentally investigated for SDS concentrations ranging from 0.025 to 1 CMC. In contrast to the constant contact angle of an evaporating sessile water droplet, we observed that, at the same surface the contact angl…