Li Menglin, Hosseinzadeh Mahmoud, Pagonabarraga Ignacio, Seemann Ralf, Brinkmann Martin, Fleury Jean-Baptiste
Experimental Physics, Saarland University, 66123 Saarbrücken, Germany.
Department of Condensed Matter Physics, University of Barcelona, Carrer de Marti i Franques 1, Barcelona, Spain.
Soft Matter. 2020 Jul 29;16(29):6803-6811. doi: 10.1039/d0sm00460j.
Droplets made of a water/ethanol mixture spontaneously self-propel in an oil/surfactant solution and, depending on the initial ethanol concentration at the time of production, may evolve in up to three stages. Upon self-propulsion the droplets absorb surfactant molecules during their continuous motion in the oily phase. In combination with the continuous loss of ethanol this mass exchange with the ambient phase may lead to a spontaneous phase separation of the water/ethanol mixture, and eventually to the formation of characteristic Janus droplets. Supported by experimental evidence, we propose a simple model that is able to explain the propulsion velocity and its scaling with the droplet radius in the last stage of the droplet evolution.
由水/乙醇混合物制成的液滴在油/表面活性剂溶液中自发地自我推进，并且根据产生时的初始乙醇浓度，可能会经历多达三个阶段的演变。在自我推进过程中，液滴在油相中连续运动时会吸收表面活性剂分子。与乙醇的持续损失相结合，这种与周围相的质量交换可能导致水/乙醇混合物的自发相分离，并最终形成特征性的Janus液滴。在实验证据的支持下，我们提出了一个简单的模型，该模型能够解释液滴演化最后阶段的推进速度及其与液滴半径的比例关系。
