Multiscale Insights into the Genesis of Pickering Emulsions: Nanomixing and Interfacial Design of Surface-Active Silica Particles.

Pickering emulsions─liquid-liquid dispersions stabilized by solid particles─offer a sustainable route for oil extraction, fine chemistry, organic synthesis, and catalysis applications. The formulation of Pickering emulsions involves surface-active particles that selectively adsorb at the interface between immiscible liquids. However, the nanoscale mechanisms that govern particle adsorption, interfacial nanostructuring, and emulsion stability remain elusive. Here, we combined molecular dynamics and dissipative particle dynamics simulations with emulsification experiments to elucidate how the length, surface density, and architecture (Janus vs homogeneous) of aliphatic ligands grafted on silica particles dictate interfacial assembly and emulsion formation in the toluene-water system. We found that longer aliphatic chains enhance the interfacial organization and stability at lower surface coverage, improving both cost efficiency and sustainability. Moreover, Janus architectures generated more robust emulsions and exhibited distinct interfacial nanomixing behavior compared with homogeneous particles. The simulations accurately predicted phase inversion transitions, consistent with experimental observations coupling water-toluene nanomixing at the microscale to emulsification at the mesoscale. This combined computational-experimental approach revealed new design rules for engineering particle-liquid interfaces with tailored stability and functionality at the nanoscale, with potential impact for surface-active catalyst design.