Tuning the electrical and magnetic properties in multifunctional composite materials based on the PEDOT:DBS conducting polymer and magnetite nanoparticles

Abstract

Composites resulting from the combination of magnetic nanoparticles (MNPs) with an electric conductive matrix have particular magnetic and electric properties. This is due to the competition between different magnetic interactions, and the existence of free electrical carriers, that may be tuned by one or by several parameters of the synthesis. Here, we synthesized composite materials by varying the relative content of poly(3,4-ethylenedioxythiophene):dodecylbenzenesulfonate and Fe₃O₄ MNP, which present magnetic and electrical conducting properties different from the ones expected from a simple dilution. The materials were characterized in terms of their morphology, structure, crystallinity, composition, electrical conductivity, and magnetic properties. Our results indicate the formation of nanoparticle cluster-like structures leading to materials with different morphologies. The distance between MNPs remains constant while the intercluster separation decreases as the PEDOT content decreases. The observed changes in the electrical conductivity are much larger than those expected for a mixture of conducting and insulating materials. The non-trivial overall magnetic behaviour of these hybrid materials is consistent with the modification of the relative intensity of their different magnetic interactions (exchange, RKKY, and dipolar). These last two facts can lay the foundation for building electric and magnetic models that capture the importance of the relevant microscopic parameters.