Electrical and surface properties of clay-conducting polymer composites

Organic guests such as aniline, pyrrole and thiophene polymerize on the surface and in the intergallery regions of smectite clays which contain exchangeable transition metal cations such as Cu²⁺ and Fe ³⁺. We monitor these reactions in thin films of smectite clays using electron spin resonance (ESR) and impedance spectroscopies. Polymers that form on the surface and in the interlayer region are studied by scanning force microscopy (SFM). ESR studies have shown that the transition metal ions are reduced during the polymerization process. Impedance measurements indicate that the formation of conducting polymer in the interlayer region of dry, Cu ²⁺ exchanged hectorite thin films results in a dramatic reduction in observed impedance. SFM scans indicate that the conducting polymers can adopt a variety of morphologies on the surfaces of the films and within the intergalleries of the host framework. These studies have applications in the development of advanced materials including microsensors and novel nanocomposites.