Effects of shell-thickness on the powder morphology, magnetic behavior and stabilityof the chitosan-coated Fe3O4nanoparticles

Abstract

Chitosan-coated Fe3O4nanoparticles were prepared by coprecipitation followed by reactionwith chitosan and different volumes of glutaraldehyde. Coating was modified by varyingthe volume of glutaraldehyde and reaction time. XRD pattern shows maxima compatibleFe3O4structure. FTIR spectroscopía confirms the presence of chitosan, more evident in sam-ples with higher chitosan content, as denoted by TGA. TEM images of samples with lowglutaraldehyde content reveal particles coated with a homogeneous chitosan shell. Mean-while, those prepared with high glutaraldehyde volume show nanoparticles dispersed in anorganic matrix. Samples present almost superparamagnetic behavior with magnetizationsaturation values that are reduced as the content of organic matter increases. Regarding thestability of these samples in solution, the presence of a homogeneous coating improves theinitial suspension, although it does not prevent its subsequent aggregation over time. How-ever, this aggregation process is reduced for sample synthesized with 1 mL of glutaraldehydeafter 6 h of reaction.