Continuous Flow Synthesis of Superparamagnetic Nanoparticles in Reverse Miniemulsion Systems

Abstract Magnetic nanoparticles were synthesized continuously in a multiphase segmented flow reaction system where one phase was a miniemulsion containing iron precursor solution in nanodroplet confinement and the other phase was diluted ammonium hydroxide solution. Spontaneous formation of reverse micelles at the phase boundary effectively transported ammonium hydroxide into the nanodroplets to trigger the precipitation of magnetic nanoparticles. The nanoparticles possessed superparamagnetism with a mean diameter of about 10 nm. This flow system is potentially generalizable to other emulsion-based continuous nanoparticle synthesis applications.