Soap bubbles exhibit abundant fascinating phenomena throughout the entire life of evolution with different fundamental physics governing them. Nevertheless, the complicated dynamics of small objects in soap films are still unrevealed. Here, we report the first observation of spontaneous particle ordering in a complicated galaxy of soap films without any external energy. The balance of interfacial tension at two liquid–gas interfaces is theoretically predicted to govern belted wetted particles (BWPs) traveling along a specified path spontaneously. Such spontaneous particle path-finding is found to depend on the particle size and hydrophilic properties. Spontaneous particle sorting is directly realized via these discrete and distinctive paths for different particles. The deformation of the soap membrane facilitates 1D/2D particle organization along the path. This observation represents the discovery of a new spontaneous order phenomenon in soap film systems and provides a new energy-free approach for particle separation and soft colloidal crystal assembly.

中文翻译：

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皂膜上的自发颗粒排序、分选和组装


肥皂泡在整个进化过程中表现出丰富的迷人现象，不同的基本物理原理控制着它们。然而，肥皂膜中小物体的复杂动力学仍未被揭示。在这里，我们报告了在没有任何外部能量的情况下在复杂的肥皂膜星系中自发粒子排序的首次观察。理论上预测两个液-气界面处的界面张力平衡将控制带状润湿颗粒（BWP）自发地沿指定路径行进。人们发现这种自发的颗粒寻路取决于颗粒尺寸和亲水特性。通过这些不同颗粒的离散且独特的路径直接实现自发颗粒分选。皂膜的变形有利于沿路径的 1D/2D 颗粒组织。这一观察结果代表了皂膜系统中新的自发有序现象的发现，并为颗粒分离和软胶体晶体组装提供了一种新的无能量方法。