Preparation of Graphene Sheets/Polyimide Nanocomposites Films by in Situ Polymerization

Graphene sheets were carbon materials with high surface area, and excellent electrical properties. One of the most promising applications of those materials is in polymer nanocomposites. Their multifunctional properties may create new applications of polymer nanocomposites. In this paper, graphene sheets were prepared by oxidation-reduction method. The graphite was oxidized by potassium permanganate and sulphuric acid. The graphene oxide nanosheets, which were exfoliated from graphite oxide by ultrasound in water, were reduced by hydrazine hydrate, and the graphene nanosheets were obtained. Thereafter, the graphene sheets were dispersed in N,N-dimethylacetamide by simple sonication treatment. The graphene sheets/polyimide nanocomposites were synthesized by in situ polymerization using N,N'-dimethylformamide, graphene sheets and pyromellitic dianhydride. It was observed from transmission electron microscopy of graphene oxide sheets and graphene sheets that the very thin sheets were obtained by exfoliation of graphite. The result of FT-IR spectral analysis for graphene sheets shows the functional groups on the graphene sheets surface were almost the same as graphite, and that means the graphene sheets were complete reduced by hydrazine hydrate. A homogeneous dispersion of graphene sheets was achieved in polyimide as evidenced by scanning electron microscopy.