Polyaniline composite coatings with thermally stable electrical properties

Polyaniline (PANI) composite coatings were prepared by polymerising aniline (ANI) monomers, which were previously embedded in an insulator polymer matrix (PMMA, PVK or PS), in an atmosphere saturated with aqueous HCl-(NH4)(2)S2O8 solution. The optical spectra and electrical measurements of these coatings clearly show the formation of the emeraldine salt of PANI in the composite materials. Sheet resistance data as well as an SEM morphology study suggest a surface polymerisation of aniline in the PANI-PMMA and PANI-PS composite coatings, whereas a volumetric polymerisation of aniline is evident in the PANI-PVK samples. The low percolation threshold (p(c)) values of these coatings suggest a fibre structure of the PANI phase inside the composite materials. The curves of current versus temperature show a higher electrical property stability of the PANI-PVK composite coatings than of a PANI single film. Copyright (C) 1999 John Wiley & Sons, Ltd.