Preparation of superparamagnetic and flexible [gamma]-Fe.sub.2O.sub.3 nanowire arrays in an anodic aluminum oxide template

Superparamagnetic and flexible Fe.sub.2O.sub.3 nanowire arrays were fabricated by the controlled electrostatic assembly of iron oxide nanoparticles and poly(dimethyldiallylammonium chloride) (PDADMAC) in an anodic aluminum oxide (AAO) template. The micrograph of iron oxide nanowire arrays was characterized by field emission scanning electron microscopy. The magnetic hysteresis loops obtained by a vibrating sample magnetometer confirm that the nanowire arrays have superparamagnetic properties. The filling ratio of iron oxide nanoparticles and polymers in the AAO template was affected by four factors, including the concentration of iron oxide nanoparticles, the pore diameter of the AAO template, the charge ratio of iron oxide nanoparticles and PDADMAC, and the molecular weight of polyacrylic acid. The effect of the AAO template on the diameter and length of the nanowire arrays was also analyzed. In addition, the nanowire arrays were shown to be flexible because of the presence of polymers. These nanowire arrays with superparamagnetic and flexural properties have potential applications in sensor probes.