Comparative Analysis of Functionalizing Magnetite Nanoparticles with Hydrophilic Polymers Using ATRP

Recent advances in colloidal science have led to various improved techniques of synthesizing magnetic nanoparticles. Thermal decomposition, for example, has been used lately to produce magnetic nanoparticles with very narrow size distribution in comparison with the co-precipitation method. The magnetic nanoparticles produced by the thermal decomposition method, however, are generally hydrophobic and require post processing to functionalize them with hydrophilic molecules particularly where biomedical applications are envisaged. Various post processing approaches have therefore been developed to exchange the hydrophobic stabilizers for hydrophilic ones.

In this work, a ligand exchange method has been used to attach initiation sites on the surface of magnetite nanoparticles. The initiator was subsequently used to functionalize the magnetite nanoparticles with different hydrophilic polymers using atom transfer radical polymerization (ATRP). The success of the ATRP was dependent on the density of the initiating sites available on the nanoparticle surface. Particularly, we compared the ATRP reaction for iron oxide particles synthesized by the thermal decomposition and co-precipitation methods. The surface properties of the nanoparticles were examined to provide an insight into the factors that promote better ligand exchange and ATRP reaction for the co-precipitation iron oxide nanoparticles.