Polymer Chain Cohesion: A Factor Influencing the Differences Between Polyaniline and Polypyrrole Nanocomposites with Zeolite and ZnO

Abstract

Department of Chemistry, University of Patras, GR-26500 Patras, GreeceSamples of conducting nanocomposites of polyaniline (PANI) and polypyrrole (PPy) with zeoliteconcentrations from 0 to 50% w/w and ZnO from 0 to 40% w/w were synthesized through oxida-tive polymerization. Their d.c. conductivity was measured under He atmosphere from 80 to 350 Kand their thermal stability was studied by heating them at 70 C for times from 0 to 600 h underenvironmental conditions. The experimental results are consistent with a granular metal structurein which conductive grains are embedded in an insulating matrix and thermal degradation is dueto the corrosion–like shrinking of them with thermal treatment. In the PANI/zeolite composites theconductivity and the thermal stability remain practically unchanged with increasing zeolite content.On the contrary, in PPy/zeolite composites these properties improve with increasing zeolite concen-tration. Moreover, SEM images and XRD patterns of PANI/ZnO composites reveal that a number ofthe ZnO particles are expelled from the matrix, although in PPy/ZnO composites ZnO is completelyencapsulated into the polymer. These differences can be attributed to the stronger bond betweenPANI chains which justify the formation of crystalline conductive grains in it, in contrast to the muchweaker packing of polymer chains in the amorphous PPy.