Preparation of narrow or mono-disperse crosslinked poly((meth)acrylic acid)/iron oxide magnetic microspheres

Abstract

Low-crosslinked poly((meth)acrylic acid-co-divinylbenzene-80) microspheres with diameters of 0.2–0.9 µm were prepared by precipitation copolymerization and distillation–precipitation copolymerization in neat acetonitrile or an acetonitrile–toluene mixture. All the microspheres prepared possessed excellent spherical shapes, smooth surfaces and narrow or mono-dispersity in size. These microspheres were used as carriers for chemical deposition of magnetic iron oxide (Fe₃O₄ or γ-Fe₂O₃) nanoparticles within them. The resulting magnetic microspheres loaded with Fe₃O₄ were superparamagnetic with little change in morphology, size and size distribution. The Fe content of the magnetic microspheres was 7.5–16 wt% and the saturation magnetization was 6.7–9.2 emu g⁻¹ of microspheres. The Fe content and the saturation magnetization of the magnetic microspheres could be further increased by repeatedly depositing iron oxide inside the microspheres.