Studies on Nanocomposite Conducting Coatings

Nanocomposite conducting coatings can impart stable surface electrical conductivity on the substrate. In this paper, carbon nanofiber (CNF) and nanographite (NG) are dispersed in thermoplastic polyurethane matrix and coated on the surface of glass and polyethylene terephthalate (PET) film. The nanoparticles dispersion was studied under TEM. The coating thicknesses were estimated. Further, their resistance and impedance were measured. It has been observed that the 5？wt% CNF dispersed nanocomposite coatings show good conductivity. The use of NG can bring down the amount of CNF; however, NG alone has failed to show significant improvement in conductivity. The nanocomposite coating on PET film using 2.5？wt% of both CNF and NG gives frequency-independent impedance which indicates conducting network formation by the nanoparticles. The study was carried out at different test distances on nanocomposite coated PET films to observe the linearity and continuity of the conducting network, and the result shows reasonable linearity in impedance over total test length (from 0.5？cm to 4.5？cm). The impedance of nanocomposite coatings on glass is not frequency independent and also not following linear increase path with distance. This indicates that the dispersion uniformity is not maintained in the coating solution when it was coated on glass. 1. Introduction Conducting coatings are essentially required for conducting, sensing, and actuating purposes mostly in biomedical, defense, and printed electronics applications. Several classes of conducting coatings exist in the market such as metallic, ceramic, carbon, and electroactive polymers. Conducting coatings are also used for applications like static charge control, electromagnetic pollution control, electromagnetic interference shielding, and so forth, [1]. Among the electroactive and conducting polymers, except for polyaniline, other conducting polymers such as polypyrrole and polythiophene are insoluble in common solvent and thus offer less choice in processing. However, electrochemical deposition and vapor phase polymerization of organic conducting polymers have been carried out on almost all surfaces which give significant rise in conductivity and electroactivity [2, 3]. The limitations of conducting polymers and metal deposition can be overcome using nanocomposite coatings in this field. Nanocomposite coatings may be advantageous over a single metal or conducting polymer coating as this possesses several features like durability, flexibility, and stability on environmental exposure. Suitable nanocomposite coating