• bifunctional diamines;
  • chain length;
  • crosslinking;
  • magnetite aggregates


We demonstrated a facile method to control magnetite clusters with different size and surface morphology by adding bifunctional diamines. First, citrate-capped magnetites (C[BOND]Fe3O4) were prepared by adding citrate ions into ferrofluid during the co-precipitation process. The resulting C[BOND]Fe3O4 was subsequently treated by diamine molecules with different chain lengths (C-4, C-8, C-12), consequently leading to the formation of diamine-linked magnetite aggregates (D[BOND]nFe3O4) with different size and surface morphology. The longer chain length of diamines increased the particle size of D[BOND]nFe3O4 due to the enhanced crosslinking between C[BOND]Fe3O4. The excessive addition of C-4 and C-12 diamines induced the significant morphological changes from irregular-shaped C[BOND]Fe3O4 to spherical and rod-shaped D[BOND]nFe3O4, respectively. Furthermore, D[BOND]nFe3O4 retained their initial magnetism under a strong oxidative process, implicating the potential application to recyclable catalyst or active electrode materials in Li-ion batteries.