Emulsion-Mediated Self-Assembly of Au Nanoparticles at Liquid–Liquid Interface: A Kinetics Perspective

Emulsion-mediated self-assembly of nanoparticles at liquid–liquid interfaces has been established, yet its particle adsorption kinetics remain largely unexplored. In this study, we investigate particle adsorption during this process by sonicating Au colloids with an oil phase. Unlike a planar water–oil interface, which poses a finite sorption energy barrier, the curved interfaces of droplets substantially lower this barrier, thereby switching the adsorption regime from kinetic control to diffusion control. In this scenario, sonication generates emulsions with a huge total water–oil interfacial area, may accelerate mass transport (acting as an agitator), and may also activate particles to overcome the residual (if any) barrier, all of which synergistically enhance particle adsorption. Furthermore, optical observations could reveal that the droplet surfaces are sparsely decorated with particle aggregates, leaving ample free area for further unimpeded adsorption, and coalescence of particle-laden droplets continuously releases particles to the planar water–oil interface, where they form a compact film. Our results might highlight effective means to enhance particle adsorption for subsequent interfacial assembly of nanoparticles.