Construction and formation mechanisms of ionic liquid-based Pickering double emulsions with Janus-like morphology

Abstract

Both Pickering emulsions containing ionic liquids (ILs) and Janus emulsions with unique features have exhibited their respective numerous advantages and significant application potentials. Therefore, the combination of the two can bring about new properties and applications. In this article, two conventional particulate emulsifiers, SiO₂ nanoparticles and graphene oxide nanosheets, are used separately to emulsify heterogeneous systems comprising ILs, organic solvents (OSs) and water (W), developing a series of IL-based Pickering double emulsions with Janus-like morphology. The (OS-IL)/W type of Pickering double emulsions with Janus-like morphology are successfully constructed by simple one-step vortex mixing process. The equilibrium configuration and stability of the emulsion droplets are regularized by the interfacial tensions among the three liquid components. Due to the relatively low interfacial tensions between ILs and W or OSs, the configurations of (OS-IL)/W Pickering double droplets are all the “complete engulfing” type with OS as the internal phase, and the double droplets have Janus-like morphology due to density mismatch between OS and IL. The formation universality of (OS-IL)/W Pickering double emulsions with Janus-like morphology is verified by using various ILs and OSs. The IL-based Pickering double emulsions with Janus-like morphology are expected to have promising application in the fields of IL-based micro-nano material creation, catalysis and so on, due to their Janus-like morphology and the functions of ionic liquids.