Magnetic properties of polyvinyl alcohol-based composites containing iron oxide nanoparticles

Abstract

This paper describes the magnetic behaviour of polymer nanocomposites containing nanoparticles (∽10 nm) of maghemite γ-Fe2O3 and magnetite Fe3O4 in a polyvinyl alcohol matrix. The compositions were synthesised using an original method of in situ preparation, the reaction of oxide formation taking place inside the polymer matrix itself. It is the one-domain-per-particle nature of magnetism in the given polymer nanocomposites that was found to be responsible for such a distinctive feature as superparamagnetism detected using Mössbauer spectroscopy and magnetisation measurements. A giant negative magnetoresistance was found in the highly filled compositions. As far as we know, this is the first time that this effect has been observed in polymer composites based on ferrite nanoparticles. Copyright © 1999 John Wiley & Sons, Ltd.