Understanding the self-assembly of the inkjet-printed CNT inks: Towards developing printable CNT inks

The printability of carbon nanotubes (CNTs) has attracted massive attention in the past few years due to its high thermal and electronic conductivities as compared to traditional metallic materials. 3D printed CNT has emerged as an important material that is extensively used in applications that involve the use of conductive wires with fine dimension and sophisticated configurations. However, the solubility of CNT in water is too low to enable any large-scale manufacturing, so graphene oxide and cellulose nanocrystal are included to help the CNT dispersion. The ink is printed through an inkjet 3D printer under an optimized pressure on a polymer surface; subsequently, the printed ink particles assemble together as the water evaporates out. The morphology and self-assembly dynamics vary dramatically with the variation in the CNT: GO/CNC ratio. Most importantly, we carry out a detailed electron microscopy analysis to relate the microscopic structural features of the ink of various compositions that result from the corresponding self-assembly with the overall printability of the ink. We anticipate that our research will be a precursor of a green technology to enable the large-scale printing of CNT.