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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Active Matter III (joint session DY/BP/CPP)

CPP 27.10: Vortrag

Mittwoch, 20. März 2024, 12:15–12:30, BH-N 334

Self-Solidifying Active Droplets Showing Memory-Induced Chirality — •Aritra K. Mukhopadhyay¹, Kai Feng², José Carlos Ureña Marcos¹, Ran Niu², Qiang Zhao², Jinping Qu², and Benno Liebchen¹ — ¹Technische Universität Darmstadt, 64289 Darmstadt, Germany. — ²Huazhong University of Science and Technology, 430074 Wuhan, China.

Synthetic microswimmers have yet to achieve the autonomy and versatility of their biological counterparts, particularly in terms of energy supply and motion diversity. Here, we introduce an all-aqueous droplet swimmer that shows remarkable autonomy and rich dynamics without any external driving mechanism [1]. Comprising a surface tension-lowering polyelectrolyte mixture, the droplets undergo self-solidification on acidic water surfaces, gradually emitting polyelectrolytes into the surroundings. A spontaneous asymmetry of the emitted polyelectrolyte concentration along the droplet surface induces Marangoni flows, which causes the droplet to self-propel. The slowly diffusing polyelectrolytes form long-lived chemical trails creating memory effects that drive a dynamic transition from linear to chiral motion. This showcases the droplet's ability to navigate its environment in a persistent, directional manner requiring no externally imposed symmetry breaking. Practical applications are highlighted through the droplets' highly efficient uranium removal from wastewater. Our results provide a route to fueling self-propelled agents that can autonomously perform chiral motion and collect toxins.

[1] K. Feng et al., Advanced Science 10, 2300866 (2023).

Keywords: active droplets; memory effect; Marangoni flow; chiral motion