Magnetic ionic liquid-water Janus droplets: Preparation, structure and morphology adjustment and magnetic manipulation

Surfactant-free magnetic ionic liquid (MIL)-water Janus microdroplets with adjustable structures and morphologies are prepared in capillary-based microfluidic devices. Their morphologies (e.g., sizes, curvatures of the interfaces, and structures from Janus to core/shell) can be adjusted in a wide range by changing the flow rate ratio of water to MIL, adding different mass fractions of polyethylene glycol in water, and using soybean oil rather than liquid paraffin as the continuous phase. MIL-water-MIL ternary Janus magnetic microdroplets with adjustable symmetric and asymmetric structures are also prepared. These Janus microdroplets can be manipulated by magnetic attraction, leading to easy formation of water-MIL-water, MIL-water-oil, necklace-structured MIL-water alternative Janus droplets as well as more complex Janus droplets, such as MIL-CO 2 -in-water and MIL-water-water droplets. Such preparation strategy is simple and can be applied in fields like pharmaceuticals, multi-drug chemotherapies, and catalysis with expensive materials. © 2017 American Institute of Chemical Engineers AIChE J , 63: 4115–4123, 2017