Tuning the size of carboxyl-functionalized Fe3O4 microspheres by changing reactant mixing process

The physicochemical properties and biomedical applications of Fe3O4 microspheres are strongly dependent on their size. Herein we report a new approach to tune the size of carboxyl-functionalized Fe3O4 microspheres via a polyol process. The diameter of Fe3O4 microspheres can be tuned in the range of 300-900 nm by simply changing the reactant mixing process while keeping other conditions constant. Mild mixing process produces Fe3O4 microspheres with large size while vigorous mixing process produces small microspheres. The mixing process does not significantly change the composition, surface and magnetic properties of the Fe3O4 microspheres. A possible mechanism for the influence of mixing process on the size of Fe3O4 microspheres is also proposed in this paper.