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.

中文翻译：

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活性水/乙醇Janus液滴的动力学。

由水/乙醇混合物制成的液滴会在油/表面活性剂溶液中自发自发地推进，并且取决于生产时的初始乙醇浓度，液滴最多可分三个阶段发展。在自推进时，液滴在油相中连续运动期间吸收表面活性剂分子。与乙醇的连续损失相结合，与环境相的这种质量交换可能导致水/乙醇混合物的自发相分离，并最终导致特征性Janus液滴的形成。在实验证据的支持下，我们提出了一个简单的模型，该模型能够在液滴演化的最后阶段解释推进速度及其与液滴半径的比例关系。