Universal Alignment of Graphene Oxide in Suspensions and Fibers

Graphene oxide (GO) has become a key component for high-performance carbon-based films or fibers based on its dispersibility and liquid crystallinity in an aqueous suspension. While the superior performance of GO-based fiber relies on their alignment at the submicrometer level, fine control of the microstructure is often hampered, in particular, under dynamic nature of GO-processing involving shear. Here, we systemically studied the structural variation of GO suspensions under shear conditions via in situ rheo-scattering and shear-polarized optical microscope analysis. The evolution of GO alignment under shear is indeed complex. However, we found that the shear-dependent structural equilibrium exists. GO showed a nonlinear structural transition with shear, yet there is a universal shear threshold for the best alignment, resulting in graphene fiber achieved an improvement in mechanical properties by similar to 54% without any chemical modification. This finding challenges the conventional concept that high shear stress is required for the good alignment of particles and their best performance.

Automated summary

Research showed that there is a universal shear threshold for the best alignment of graphene oxide particles under shear conditions, leading to a significant enhancement in the mechanical properties of graphene fibers without the need for chemical modification.