Anisotropy of graphene scaffolds assembled by three-dimensional printing

The research focuses on fabrication of graphene scaffolds by three-dimensional printing and their anisotropic properties. A novel strategy to prepare printable graphene ink is reported first, and three-dimensional scaffolds with high content (50 wt %) and aligned graphene are achieved by three-dimensional printing. Adequate shear thinning and rheology behavior are required for printable graphene ink to flow through the nozzle smoothly and self-support during the printing process. The scaffolds with different contents and printing parameters exhibit good resolution and good bonding between layers. The alignment of graphene sheets along the direction of flowing can be observed due to the shear stress in the nozzle. When the temperature rises up to 450 degrees C, electrical conductivities along transvers and longitudinal directions of 50 wt % are enhanced to 479.2 and 425.6 S/m, which are 6.7 and 8.4 times higher than that at room temperature, respectively. The alignment can contribute to the electrical anisotropy of three-dimensional graphene scaffolds. The electrical resistance variations under compression and electrical anisotropy demonstrate the potential application of the graphene scaffolds in electrical device, sensor, especially combined with three-dimensional printing. (C) 2018 Elsevier Ltd. All rights reserved.