Nanocomposites combining conducting and superparamagnetic components prepared via an organogel

Abstract

A nanocomposite material combining an organic molecular gelator and oleate-coated iron oxide nanoparticles in proportions which range from one to fifty weight percent of the inorganic material has been prepared via the gel state. The proportion of nanoparticles and organic gelator in this mixed colloidal system gives very different characteristics to the final hybrid xerogel. Characterisation of the xerogels by transmission electron microscopy shows that at low loadings of the inorganic material a uniform distribution is observed, while above ten weight percent of nanoparticles a clear phase separation of the components (organic and inorganic) is revealed. Doping of the organic component of the xerogels by chemical oxidation results in the formation of conducting composites, whose electrical characteristics—probed by current sensing atomic force microscopy and spectroscopy—vary importantly with the amount of iron oxide colloid. The best conductors are found at low loadings of inorganic particles, at which an interesting alignment of the organic fibres is observed. The work shows that conducting materials incorporating magnetic particles can be prepared simply through the organogel route, and raises possibilities for the discovery of new properties that could come from the combination of these or related systems.