Microscopic insight into all liquid constructs – ‘Structured Liquids’

Our ability to lock in non-equilibrium all liquid constructs has generated  enormous interest in applications such as all liquid electronics, compartmentalized reaction vessels, all liquid microfluidics and energy storage devices in the past decade. Harnessing the complementary chemical functionalities of Nanoparticle-Surfactant (NPS) and tailoring the interactions and assemblies in-situ, leads to reduction in the interfacial energy at 2D liquid interfaces. However, direct visualization of the interfacial assemblies of NPSs in-situ and understanding the underlying physics that governs the applications is unexplored and challenging. Here, we leverage state-of-the-art imaging techniques such as in-situ liquid phase Laser Scanning Confocal Microscopy (LSCM) and Scanning Probe Microscopy (SPM), to elucidate the details of the structure and dynamics of assembly of NPSs that enable structuring liquids. While the assemblies at low ligand concentrations are well understood, microscopic insight at high ligand concentrations shows that the interface is more complex. Our time-resolved microscopy results point to non-equilibrium assemblies of NPS at the interface, which deviate significantly from the monolayer model of Pickering emulsions, accompanied by other interesting phenomenon in the bulk phases. Our experiments render deeper insights into the adsorption, self-assembly and reorganization of NPS at liquid-liquid interfaces, enabling design of all liquids advanced functional materials.