Self-Swimming Droplets Driven by the Synergistic Effects of the Fast Interfacial Polymerization and Hydrolysis Reactions

Self-swimming droplets, as an intriguing phenomenon in the microscopic realm, have traditionally been achieved by harnessing the interfacial properties of small-molecule emulsifiers. Herein, we successfully prepared self-swimming droplets by employing polymers. Leveraging the synergistic effects of fast interfacial polymerization and hydrolysis reactions, a polymer layer is rapidly formed at the oil-water interface, followed by the generation of weakly amphiphilic substances that establish an interfacial tension gradient. Thus, strong Marangoni circulation flows were induced to propel the droplets to move spontaneously. The interfacial behavior of the self-swimming droplets was investigated, revealing regular oscillations and the spontaneous formation of microdroplets on the larger droplet surface. Comparative experiments confirmed the synergistic effects of the two types of reactions in forming self-swimming droplets, as the absence of either reaction hindered autonomous movement. The movement time reaches 758 s, and the maximum speed of droplet movement reaches 5.08 mm/s. This work not only enriches the variety of self-swimming droplets but also provides theoretical guidance for designing and preparing innovative self-swimming systems.