Graphene, a two-dimensional monolayer of sp2-bonded carbon atoms, has been the focus of much research since its isolation because of the unique transport properties. High conductivity, high surface area, mechanical/chemical stability and good stretchability/flexibility are the vital reasons behind this rapidly growing research interest and also make graphene a promising material for various applications. To exploit the potential of graphene-based materials for versatile applications, graphene/conducting polymer composite has been prepared to enhance graphene based materials' physical/chemical properties. Among these candidate polymers, polyaniline (PANI) is most often used to be blended with graphene due to its tremendous applicability. Some recent studies have already demonstrated that graphene/PANI composites can be successfully prepared by in situ chemical or electrochemical polymerization. Typically, the monomer (aniline) is mixed with graphene oxide (GO) solution and polymerized at a specific reaction condition. However, the method is difficult to synthesize PANI with high aspect ratio (e.g., nanorod, nanofiber) due to the complicated reaction composition. Furthermore, it is difficult to control the degree of dispersion of GO within the polymer hosts, and the favorable interfacial interactions between these two phases. Structurally, GO can be considered as a two-dimensional molecular amphiphile, with hydrophobic ? domains interspersed on its basal plane and hydrophilic -COOH groups on the edges. Recently, some studies show that GO can act like a surfactant to process insoluble materials such as graphite and carbon nanofibers in water. To prepare the rGO and nanofiber PANI composite, we synthesized nanofiber PANI firstly, and applied GO as surfactant to disperse the PANI forming a stable GO/PANI solution. In order to fully reduce the GO without overdoping the PANI, we use CO2 supercritical fluid (CSF) combining vitamin C as the reductant to reduce the GO. In the CSF environment, the high pressure can assist the reductant to penetrate into the GO film leading to a complete reduction state. In this way, we can prepare an uniform rGO/nanofiber PANI composite which can apply for transparent electrode for organic solar cells (OSCs).

Versatile composite materials based on graphene and polyaniline fiber for energy applications

244th National Meeting (2012)

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