Chemically stable conducting polyaniline composite coatings

Aniline monomer was dispersed in polymethyl methacrylate (PMMA) and polyvinyl carbazole (PVK) solutions. The resulting mixtures were coated on substrates, dried in toluene atmosphere and enclosed later on in a chamber containing an oxidized atmosphere of HCl and (NH4)(2)S2O8. Electrical and optical characterizations indicate that polyaniline (PANI) was formed in the PMMA and PVK matrixes. Sheet resistance as a function of the pH value demonstrates that both PANI-PMMA and PANI-PVK composite coatings keep their R-square almost unchanged when they are immersed in a moderate basic solution (pH similar to 9). Especially, PANI-PVK coatings are more stable than PANI-PMMA samples for longer time of immersion and also in solutions with a higher pH value, Scanning electron micrographs show different surface morphologies of these two composite materials suggesting a possible explanation of their chemical stability. (C) 1998 Elsevier Science B.V. All rights reserved.