Preparation of hybrid hollow capsules formed with Fe3O4 and polyelectrolytes via the layer-by-layer assembly and the aqueous solution process

Well-defined magnetic hybrid hollow capsules formed with magnetite (Fe3O4) and polyelectrolyte-multilayer films were Successfully prepared through colloidal templating with layer-by-layer assembly of polyelectrolytes, followed by aqueous solution deposition of Fe3O4. Pd catalyst nanoparticles played an important role in the deposition of Fe3O4. Pd nanoparticles favorably adsorbed onto the polyelectrolyte layer with positively charged amino groups. Hollow capsules were obtained by the removal of the melamine-formaldehyde Core particles. Although the Processes were performed in aqueous solutions at temperatures less than 60 degrees C, X-ray diffraction patterns revealed that the deposited Fe3O4 was highly crystallized. The hollow capsules were stably dispersed in water; however, the Capsules rapidly congregated around a locally applied magnet. (C) 2009 Elsevier Inc. All rights reserved.