Preparation, Characterization and Conducting Properties of Nanocomposites of Successively Intercalated Polyaniline (PANI) in Montmorillonite (MMT)

Abstract

This paper describes the preparation and characterization of conducting polyaniline-montmorillonite (PANI-MMT) nanocomposites by the polymerization of anilinium ions within the interlayer space of MMT particles. A procedure for the successive introduction of PANI chains within the interlayer galleries of MMT is developed. The d-spacing, measured after heat treatment at various temperatures serves as a measure of the amount of polymer inserted in the clay intergalleries. The FTIR spectroscopy reveals the presence of host-guest interactions of a hydrogen-bonded nature. The DC conductivities were found to increase with the amount of PANI intercalated. Anilinium ions supported on kaolinite tended to dislodge from the surface upon repeated washings, as shown by the absence of polymer formation on such samples upon treatment with the oxidant. In MMT, however, polymerization is observed even with exhaustively washed samples, thus confirming that the successive polymerization processes occur within the interlayer galleries. Exclusion of the washing stage gives a composite material in which polyaniline is present on both the internal and external surfaces. This material is found to have significantly higher electronic conductivities than the composites where the polymer is restricted to interlayer galleries. The washed samples of the polymer once loaded into the clay (EMS1-MMT), twice loaded into the clay (EMS2-MMT) and thrice loaded into the clay (EMS3-MMT) have electrical conductivities of 4.5 × 10−5, 3.0 × 10−4, and 1.0 × 10−3 Scm−1, respectively in their dry states. The corresponding samples prepared by excluding the washing procedure had the values of 4.0 × 10−4, 1.0 × 10−2, and 1.0 10−1 Scm−1, respectively.