Structured droplets dominated by interfacial self-assembly of topology-tunable Janus particles towards macroscopic materials

Structured droplets, constructed and stabilized by interfacial self-assembly and jamming of colloidal particles, have shown potential applications in biphasic reactors towards fabrication of functional materials. However, the fabrication of macroscopic granular materials using structured droplets remains a great challenge due to the instability of colloidal particle assemblies at the macroscale droplet interface and the coalescence between droplets. Herein, we demonstrate a distinctly interfacial self-assembly of topology-tunable Janus particles (including bread, hemisphere and crescent) at the macro-droplet interface, enabling the fabrication of stably structured droplets with a solid-like membrane and thereby greatly affording the downstream production of macroscopic granular materials. The self-assembly towards the fabrication of structured droplets is attributed to the interfacial desorption energy difference triggered by Janus particle topologies. Only hemispherical Janus particles could perform fully interfacial jamming, thereby forming the robust structured droplets. These Janus particle-dominated structured droplets as a biphasic reactor can be used to controllably produce macroscopic granular materials with tunable sizes and functionalities. This study will widen the applications of the interfacial self-assembly from the microscale to the macroscale towards the fabrication of functional materials.