Surface-initiated polymerization for the preparation of magnetic polymer composites

Abstract

In organic–inorganic hybrid materials, it is difficult to obtain magnetic polymer microspheres with the good encapsulation of magnetic materials because there are few successful interactions between monomers and magnetic materials. In this study, a method involving surface-initiated polymerization was developed for the preparation of magnetic polymer composites; the method used Fe₃O₄ nanoparticles and H₂O₂ as a redox initiator. After activation with carboxylic acid, the amount of Fe²⁺/Fe³⁺ on the surfaces of the Fe₃O₄ nanoparticles increases, which can effectively catalyze the decomposition of H₂O₂ to produce hydroxyl radicals. The hydroxyl radicals were used to initiate the polymerization of the monomers on the surfaces of the Fe₃O₄ nanoparticles so that the Fe₃O₄ nanoparticles became encapsulated in polymer microspheres and in this way highly magnetic responsive polymer microspheres were obtained. This method was found to be applicable to the polymerization of many types of monomers, and some polymer microspheres (PS, PMMA, PBA and PVAc) were synthesized successfully. The effects of reaction time, concentration of the added Fe₃O₄, volume of the added styrene monomer, and volume of the added H₂O₂ on the prepared Fe₃O₄@PS composites were investigated. The results indicated that the polymer microsphere size was controllable (60 nm–2 μm) and the load of Fe₃O₄ nanoparticles in the polymer microspheres could be adjusted by the addition of Fe₃O₄ nanoparticles. This method was beneficial for preparing various magnetic polymer composites having significant potential application value in many fields.