Carbon nanofiber network made by electrohydrodynamic casting immiscible fluids

Abstract

This paper presents how to control the micro- and nanostructures of partially polymerized carbon materials through electrohydrodynamic casting. Polyacrylonitrile (PAN) was dissolved into dimethylformamide (DMF) to form a polymer solution. The weight percentage of polyacrylonitrile was 10%. This solution was used as the precursor to generate polyacrylonitrile nanofibers and networks (meshes) in the electrohydrodynamic co-casting processes. Subsequently, heat treatments on the PAN nanofibers and meshes in air and argon gas were conducted to obtain partially carbonized materials. It has been found that the morphologies of the polymeric carbon materials are affected by the miscibility of different fluids used in the electrohydrodynamic co-casting processes. Co-casting two immiscible fluids, silicone oil as the core fluid and 10% polyacrylonitrile in dimethylformamide as the sheath fluid, resulted in the formation of nanofiber networks. But co-casting two identical miscible fluids, i.e. 10% polyacrylonitrile in dimethylformamide as both core fluid and sheath fluid or using single jet casting 10% polyacrylonitrile in dimethylformamide, only generates long and uniform nanofibers. The carbon network structure development in the electrohydrodynamic casting process was discussed. Photosensitive tests showed that the carbon fiber network is p-type. Heat treatment improves the electrical transport behavior of both the nanofiber and the fiber network structure through the reduction in their electrical resistivity significantly.