Superparamagnetic SiO2@Fe3O4 core/shell fabrication via low-temperature electroless deposition

Abstract

Magnetite (Fe3O4) coated nanoparticles combine magnetic properties of magnetite with low density of core particles. This category of magnetic responsive core/shell particles takes advantage of the physical and chemical properties of particle core and can be used in numerous suspension-based applications such as biosensors, cargo particles and in magnetorheological (MR) fluids. A facile, controllable, and scalable particle surface modification methodology is required to synthesize magnetite-coated nanoparticles. In this study, we fabricated a monodisperse magnetic particle using low-temperature electroless deposition technique to deposit a magnetite layer on the surface of silica (SiO2) particle. Silica particle was synthesized, functionalized with amine as the intermediate agent and catalyst, and subsequently dispersed in a solution of iron (III) salt and a reducing agent. This technique implemented at low temperatures in a simple experimental setup can be applied to generate magnetite layer on wide varieties of particles made of inorganic materials or polymers and is scalable for mass manufacture. The fabricated SiO2@Fe3O4 core/shell particle was responsive to the magnetic field, forming persistent structures that make it a good candidate for magnetorheological fluid application.