Morphological changes of magnetite clusters into rod-shaped magnetites with diamine molecules

Citrate-capped magnetite clusters (C-Fe₃O₄) were prepared by adjusting the injection times of citrate ions during the co-precipitation process of a modified Massart´s method. The resulting C-Fe₃O₄ was treated by bi-functional diamines with different chain lengths, consequently leading to the aggregation and/or morphological changes of magnetite clusters due to their molecular bridging effect. The longer chain length of diamines induced larger aggregation of C-Fe₃O₄ possibly due to the enhanced chain flexibility of diamine linkers. Diamine-linked C-Fe₃O₄ (D-Fe₃O₄) exhibited narrower size distribution and even morphological transformation into rod-shaped magnetites. The characteristic properties of magnetite clusters were analyzed by dynamic light scattering (DLS), scanning electron microscope (SEM), and Fourier transform infrared (FTIR).