Solventless thermal decomposition of ferrocene as a new approach for the synthesis of porous superparamagnetic and ferromagnetic composite microspheres of narrow size distribution

In previous publications we described various methods to prepare ferromagnetic poly(divinylbenzene)/iron oxide and C/iron oxide composite microspheres for various biomedical applications. However, these particles suffer from a few significant shortcomings, such as the high toxicity of the precursor (iron pentacarbonyl) used for obtaining the magnetic particles, broad size distribution, etc. In addition, superparamagnetic particles could not be obtained by the previous methodology. The present work describes a new approach to overcome these obstacles. Superparamagnetic poly(divinylbenzene)/iron oxide composite microspheres of narrow size distribution were prepared by entrapping ferrocene and separating media within the pores of uniform porous PDVB microspheres, followed by the solventless thermal decomposition at 300 °C in ambient atmosphere in a sealed cell. Uniform ferromagnetic C/iron oxide and C/Fe₃O₄/Fe composite microspheres were then formed by annealing the superparamagnetic PDVB/iron oxide particles at 500 and 700 °C, respectively, under argon atmosphere.