Engineering Morphologies of Metal-Based Colloidal Assemblies via Colloid Jamming at Liquid-Liquid Interfaces

Assemblies structured from colloids exhibit promise for advanced applications, including photonic devices, electrochemical energy storage systems, and catalytic supports. Despite observing diverse morphologies, a comprehensive understanding of the underlying formation mechanisms remains elusive. In this work, it is proposed that the coordination interactions between metal sulfide nanoparticles (MS NPs) and fluorosurfactants at the droplet interface influence the morphology of assemblies during the evaporation-induced self-assembly in droplet microfluidics. Systematic studies suggest that coordination strength significantly influences the morphology of assembly. The interfacial interactions can be effectively eliminated by coating the MS NPs with a SiO₂ shell, forming metal sulfide@SiO₂ nanoparticles (MS@SiO₂ NPs). Furthermore, it is demonstrated that the morphology of assemblies can be engineered via tuning MS NPs concentration under coordination regulation. With interfacial jamming, core-shell or homogeneously distributed binary colloidal assemblies are constructed. These findings highlight the importance of coordination interactions and concentration in shaping colloidal assemblies during evaporation-driven self-assembly in surfactant-stabilized microdroplets. This insight provides a foundation for designing functional materials with controlled architectures for applications in catalysis, plasmonics, and porous materials.