Synthesis and characterization of double surfactant coated magnetic particles

Abstract

The unique and novel physicochemical features of the nanosized magnetic particles, which are attained due to their size and shape morphology, have aggregated an interest in the fields of nanoscience and nanotechnology. In this work, magnetic particles coated with double-layer surfactants were prepared and characterized. The magnetic particles (Fe 3O 4) were synthesized by chemical precipitation of Fe 2+ and Fe 3+ salts (1:2 ratio) with ammonium hydroxide (NH 4OH) under inert atmosphere at 80° C followed by resuspension of the nanoparticles in water using thiodiglycolic acid. This procedure produced Fe 3O 4 nanoparticles stabilized against agglomeration. The primary surfactant coated particles were further treated with 4-vinylaniline at 25°C for about thirty minutes. As -SH group in thiodiglycolic acid has greater affinity for magnetic surface, it is easily attached to the iron particles through bonding. Subsequently, the -NH 2 functional group of 4-vinylaniline reacts with the acid group -COOH of the thiodiglycolic acid. The size and the distribution of these magnetic particles, their morphologies and magnetic properties were measured by Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM), respectively. TEM results show the formation of single domain nanoparticles of mean diameter of about 10 nm. The strength of the NH-CO bond was measured by FTIR (Bio-Rad), the vibration observed at a wavelength of 1613-1745 cm -1. Thermo gravimetric analysis (TGA) reveals the existence of two distinct layers of surfactants on the particle surface. These surface-modified nanomagnetic particles can further be coated with thermo-sensitive polymeric materials which may be used in separation and purification of bio-molecules. © World Scientific Publishing Company.