Printability study of self-supporting graphene oxide-laponite nanocomposites for 3D printing applications

Graphene, a two-dimensional (2D) carbon allotrope, has been widely used in various fields due to its excellent inherent properties. Graphene and its derivatives usually possess poor printability, which makes it challenging to create three-dimensional (3D) structures. The objective of this work is to investigate a nanoclay-assisted 3D printing approach to print 3D structures from self-supporting graphene oxide (GO)-laponite nanocomposites. Due to the physical crosslinking between nanoclay and GO, the resulted nanocomposites can be directly printed into complex geometries in air. A significantly large range of laponite to GO mass ratio (5.00 to 32.00) was achieved by a mixing and centrifuging method as compared to previously reported GO-laponite composites made by the solvent evaporation method. It is found that the concentrations of nanoclay additives and GO can significantly affect the extrudability. In addition, the formability of the extruded filaments was studied by assessing the filament shapes/dimensions as well as the filament deflections when printing between supporting structures. Our results show that operating conditions such as dispensing pressure, path speed, nozzle diameter, and stand-off distance can be used to control the width of printed filaments on a substrate. Due to the self-supporting property of the proposed GO-laponite nanocomposites, it is possible to form continuous filaments with negligible deflections between supporting structures. Thus, 3D scaffolds with well-defined shape and controllable geometries have been successfully fabricated, which proves the proposed nanoclay-assisted 3D printing technology to achieve complex 3D graphene structures is feasible.