Flexible and Conductive Graphene-Poly (diallyldimethylammoniumchloride) Buckypaper.

This paper describes the fabrication and characterization of flexible, conductive reduced graphene oxide (rGO)-poly(diallyldimethylammoniumchloride) (PDDA) buckypaper (BP). PDDA acts as a reducing agent to prepare an rGO-PDDA nanosheet dispersion from graphite oxide. The incorporation of PDDA as a "glue" molecule successfully binds rGO nanosheets into BPs with strong interlayer binding. The resulting BPs were characterized by scanning electronic microscopy (SEM), Raman, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and resistivity measurements. The sp2 structure was greatly restored by the PDDA-induced reduction. Moreover, rGO was chemically doped from the adsorbed PDDA, which causes the Raman G band to shift from ~1585 to ~1610 cm(-1). This chemical doping substantially increased the density of the free charge carriers in rGO and thereby further enhanced the electrical conductivity of the rGO-BP. Good inter-layer connection in the rGO percolating network was obtained after thermal annealing at higher than ~250 °C. The resulting rGO-PDDA-BPs exhibited an isotropic sheet resistance as low as ~100 Ω/sq, which indicates a reduction by six orders of magnitude compared to the GO-BPs resistance before annealing. This PDDA-induced reduction with a low-temperature annealing process preserved the BPs' structural integrity and mechanical flexibility, thus overcoming the fragility problems with high-temperature annealing.