Physics Department - Active Dynamics and Self-Assembly Driven by Ion-Gradient-Induced Interfacial Flows

Abstract
Catalytic colloidal particles release ions through surface chemical reactions, generating localized concentration gradients that induce interfacial flows. In this talk, I will present how these flows drive and regulate autonomous motion, self-assembly, and a wide range of dynamical behaviors. We extend the classical theory of ionic diffusiophoresis to the colloidal scale, enabling a quantitative description of multiple experimentally observed phenomena. Specifically, we systematically analyze how key factors—including surface potential, ionic strength, fuel concentration, and particle morphology—govern the speed and direction of active colloid motion. We further elucidate the translational and rotational dynamics exhibited by active–passive binary assemblies. Finally, I will introduce our findings on surface-anchoring–condition–controlled rotary dynamics and morphology-tailored dynamic state transitions. Together, these studies deepen our understanding of the propulsion mechanisms of chemically active colloids and provide a theoretical framework and experimental basis for predicting collective behaviors in multi-particle systems, designing high-performance micro/nanomotors, and constructing multicomponent micro/nanomachines.