Emulsion-based synthesis of reversibly swellable, magnetic nanoparticle-embedded polymer microcapsules

A one-step, template-free synthetic method for preparing polymeric microcapsules with iron oxide (gamma-Fe2O3) magnetic nanoparticles (MPs) embedded in the polymer shell is reported. Using a simple emulsification of the multiphase mixture containing liquid prepolymer and MPs in chloroform solution, double emulsions comprising a chloroform core and MPs/polymer shell were spontaneously formed. After exposure to UV light, these double emulsions converted to microcapsules with a polymerized composite shell. The evolution from the double emulsions to the microcapsules was examined by confocal laser scanning microscopy. One unusual feature of these microcapsules is the ability to change shape reversibly by osmotic swelling of the water core upon repetitive drying and hydration. The microcapsules had an intrinsic superparamagnetic response due to the presence of the magnetic nanoparticles and could be moved and collected by external magnetic fields.