Morphology and Electrical Conductivity of Polystyrene Sulfonic Acid-Graphite Nanosheet Composites

Polystyrene sulfonic acid (PSS) was prepared by sulfonating polystyrene (PS), obtained by emulsion polymerisation of styrene. Sulfonate groups were introduced on the phenyl groups of PS. Nanocomposites were prepared by dispersing nanoscale graphite (NanoG) in PSS aqueous solution with the aid of sonication, and casting the dispersion on a plastic film. The sulfonate anions on PS resulting from the ionisation of sulfonic acid groups facilitated the dispersal of NanoG carrying the positive charges. Scanning electron microscopy was used to characterise the morphologies of expanded graphite, NanoG and the nanocomposites, and the results showed that the graphite sheets varied in thickness from 40 to 70 nm. Transmission electron micrographs revealed that the PSS was intercalated into the sub-layers of nanoG homogeneously. The electrical conductivity of the nanocomposites reached 1.25 × 10 ⁻⁴ S.cm ⁻¹ at a concentration of 0.2 vol.% and the electrical conduction phenomenon could be interpreted by classic percolation theory.