3D printing by tailored extrusion of carbon nanotube inks

3D printing through direct-ink writing builds objects by layerwise deposition of material; and the properties of the final object are governed both by the ink and by the hierarchical organization within and across layers. In extrusion 3D printing of thermoplastics, strength and thermal stability can be improved by addition of rod-like fillers such as carbon nanotubes (CNTs) or carbon/glass microfibers. However, the mechanical properties of 3D printed objects are far from those achieved by spinning of continuous fibers out of the same material.l. We study the flow-mediated structure evolution of rigid rod-like particle-based inks using single-walled carbon nanotubes (SWCNTs) at high concentrations from 0.7-1%wt. We report the influence of processing parameters such as the flow rate, rate of elongation, and rate of reaction or diffusion on the strength, conductivity, and dimensions of the extruded filament, and of printed test artifacts. Our results suggest that 3D printing processes for architected materials can be improved by incorporating key principles of fiber spinning.