Synthesis and characterisation of polymer-coated metallic magnetic materials

Polymer-coated magnetic microspheres can be used for bioengineering applications; hence, the synthesis and characterization of such materials was studied. Cobalt and iron powders were ball milled and subsequently characterized by scanning electron microscopy (SEM) and XRD methods. The average size of the ball milled Co powders was 7.4 μm after 1 h of milling; for Fe, the smallest average size was 808 nm after 10 h of milling. These milled powders were then coated, using the solvent evaporation technique with the polymer poly-l-lactic acid (PLLA) to form microspheres. The process parameters to form microspheres with the smallest diameter, spherical morphology and a narrow size distribution was determined. The stirring speed and polymer viscosity were found to control the size and shape of microspheres. The Co and Fe microspheres had an average size of 105 and 125 μm, respectively. The VSM results showed that saturation magnetization decreased with polymer coating thickness.