Facile method for preparation of anisotropic submicron magnetic Janus particles using miniemulsion.

Submicron hybrid magnetic, polystyrene (PS) based Janus particles containing magnetic nanoparticles (MNPs) on one side were successfully assembled using the miniemulsion/solvent evaporation method. Nanodroplets of styrene (St) monomer in the presence of PS and MNPs were generated in an aqueous continuous phase. The subsequent evaporation of St monomers resulted the precipitation of PS and MNPs into spherical nanoparticles. The effect of PS content, oil:water phase ratio, MNPs:PS ratio, and type and concentration of stabilizers on Janus morphology was investigated. A MNPs:PS weight ratio of 1:1 promoted the formation of Janus-like particles with MNPs located on one side due to the increased PS concentration during evaporation of the monomer solvent. Of the stabilizing agents tested (sodium dodecylsulfate (SDS), Triton X-405, polyvinyl alcohol, and Pluronic F-68), the presence of 1.0 g L(-1) SDS and 20.0 g L(-1) Pluronic F-68 was found to effectively stabilize hybrid particles with Janus morphology.