Multifunctional layer-by-layer self-assembly of conducting polymers and magnetic nanoparticles

Multifunctional thin films having both electrical conductivity and ferrimagnetic properties were successfully fabricated by the layer-by-layer self-assembling (LBL-SA) method, i.e. successive ionic adsorption of polypyrrole (PPy) and ferrite nanoparticles from their aqueous solutions. Using an ellipsometer, a constant increase of the film thickness by each deposition was characterized. implying a controllable process of the LBL-SA for multifunctional thin films. Uniformly distributed ferrite nanoparticles in the thin film were also observed in scanning and transmission electron microscopic images. The thin film consisting of six PPy and two ferrite nanoparticle layers had a conductivity of 0.18 S/cm and simultaneously showed a magnetic hysteresis. (C) 2002 Elsevier Science B.V. All rights reserved.