Facile synthesis of monodisperse superparamagneticFe3O4/PMMA composite nanospheres with high magnetization

Abstract

Monodisperse superparamagneticFe3O4/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetizationwere successfully prepared by a facile novel miniemulsion polymerizationmethod. The ferrofluid, MMA monomer and surfactants were co-sonicated andemulsified to form stable miniemulsion for polymerization. The samples werecharacterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of theFe3O4/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersityindex (PDI) as small as 0.099, which indicated that the nanospheres haveexcellent homogeneity in aqueous medium. The TEM results implied that theFe3O4/PMMA composite nanospheres had a perfect core–shell structure with about 3 nm thinPMMA shells, and the core was composed of many homogeneous and closely packedFe3O4 nanoparticles. VSM and TGA showed that theFe3O4/PMMA composite nanospheres with at least 65% high magnetite content weresuperparamagnetic, and the saturation magnetization was as high as around 39 emu g − 1 (total mass), which was only decreased by 17% compared with the initial bareFe3O4 nanoparticles.