Characterization and electrical properties of conductive polymer/colloidal graphite oxide nanocomposites

Conductive polymers such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) have been synthesized in the presence of colloidal graphite oxide (CGO) prepared via Hummers and Offerman's method, thus obtaining PPy/CGO and PEDOT/CGO nanocomposites. The resulted nanocomposites provide high and adjustable electrical conductivity when doped with different dopants, and a much better thermal stability than pristine CGO. For the case of doped PPy/CGO nanocomposites, CGO is confirmed experimentally to be exfoliated and thus could offer more active sites for the polymerization of pyrrole. For the case of doped PEDOT/CGO nanocomposites, X-ray diffraction analyses indicate the formation of PEDOT with the aid of CGO in aqueous media in spite of its monomeric water insolubility and a possible part intercalation of PEDOT between the layers of CGO. The temperature dependence of conductivity supports the three-dimensional Mott's variable range hopping mechanism for doped PPy/CGO and PEDOT/CGO nanocomposites. The Fourier-transform infrared (FTIR) spectroscopy and electron spin resonance (ESR) spectra data, as evidence verifies that the charge carriers in doped PPy/CGO nanocomposites are polarons, while bipolarons serve as charge carriers in doped PEDOT/CGO nanocomposites. (C) 2009 Elsevier Ltd. All rights reserved.