Formation and microscopic investigation of iron oxide aligned nanowires into polymeric nanocomposite films

We present a microscopic investigation of nanocomposite films of iron oxide (γ-Fe₂O₃) magnetic nanowires (NWs) aligned into polymers, formed upon evaporation of solutions of acrylate polymer/magnetic nanoparticles under magnetic field (MF). The field causes the assembly of the γ-Fe₂O₃ nanoparticles along the direction of the MF lines, resulting in magnetic NWs embedded throughout the entire volume of the polymer film. The scanning electron microscopy and the transmission electron microscopy studies show that the cylindrical-shaped NWs have ~15-μm average length and are isotropically distributed throughout the film. The study with the MF microscopy technique not only proves that the composed NWs are magnetic but also makes possible the magnetic study of each individual NW in a nondestructive way. In this way it becomes possible for the localized study of the magnetic properties alteration after the binding of various molecules onto individual NWs, opening up the way of using these films in sensor devices applied in various fields ranging from biology to environmental purposes. Microsc. Res. Tech. 73:952-958, 2010.