Influence of Surface Functionalization on the Colloidal Stability and Magnetic Properties of Ferrite Nanoparticles

TL;DR

This study investigates how surface functionalization with PEG and citric acid affects the structural, colloidal, and magnetic properties of Fe3O4 nanoparticles, demonstrating improved stability and coating-dependent magnetic behavior.

Contribution

It provides a systematic analysis of surface modification effects on Fe3O4 nanoparticles' properties using chemical co-precipitation and various characterization techniques.

Findings

Surface modification improves colloidal stability and dispersion.

All samples exhibit superparamagnetic behavior with reduced saturation magnetization.

Surface chemistry critically influences the physicochemical and magnetic properties.

Abstract

Magnetite ferrite (Fe3O4) nanoparticles have attracted considerable interest due to their tunable physico-chemical properties and relevance in functional materials. In this work, uncoated Fe3O4 nanoparticles and surface-modified Fe3O4 nanoparticles coated with polyethylene glycol (PEG-6000) and citric acid (CA) were synthesized via a chemical co-precipitation method. The effect of surface functionalization on the structural, spectroscopic, magnetic, and colloidal properties of the nanoparticles was systematically investigated. X-ray diffraction analysis confirmed the formation of phase-pure Fe3O4 with an inverse spinel structure for all the samples. Fourier transform infrared and Raman spectroscopy verified successful surface modification while preserving the Fe-O framework of the magnetite core. Dynamic light scattering and zeta potential measurements indicated improved dispersion and colloidal stability for the surface-modified nanoparticles. Magnetization studies performed at room temperature revealed superparamagnetic behaviour for all samples, accompanied by a coating-dependent reduction in saturation magnetization. Overall, the results emphasize the critical role of surface chemistry in tailoring the physicochemical, magnetic, and colloidal behaviour of Fe3O4 nanoparticles. Keywords: Fe3O4 nanoparticles, PEG, Citric acid, Co-precipitation, Surface functionalization, Zeta potential, Colloidal stability, Magnetic properties