Hybridizing wood cellulose and graphene oxide toward high-performance fibers

Abstract

High-performance microfibers such as carbon fibers are widely used in aircraft and wind turbine blades. Well-aligned, strong microfibers prepared by hybridizing two-dimensional (2D) graphene oxide (GO) nanosheets and one-dimensional (1D) nanofibrillated cellulose (NFC) fibers are designed here for the first time and have the potential to supersede carbon fibers due to their low cost. These well-aligned hybrid microfibers are much stronger than microfibers composed of 1D NFC or 2D GO alone. Both the experimental results and molecular dynamics simulations reveal the synergistic effect between GO and NFC: the bonding between neighboring GO nanosheets is enhanced by NFC because the introduction of NFC provides the extra bonding options available between the nanosheets. In addition, 1D NFC fibers can act as ‘lines’ to ‘weave and wrap’ 2D nanosheets together. A 2D GO nanosheet can also bridge several 1D NFC fibers together, providing extra bonding sites between 1D NFC fibers over a long distance. The design rule investigated in this study can be universally applied to other structure designs where a synergistic effect is preferred. Scientists in the US and China have produced strong microfibres by combining 2D graphene oxide nanosheets and 1D nanofibrillated cellulose. The low cost of production of these fibres could make them attractive for replacing carbon fibres, the researchers say. They produced these fibres by wet spinning a liquid-crystal solution of the nanosheets and the nanofibrillated cellulose, which were derived from wood cellulose. The hybrid fibres were much stronger than their components. Experimental results and molecular dynamic simulations reveal that this improved strength is due to a synergistic effect — bonding between adjacent graphene oxide nanosheets is enhanced by the nanofibrillated cellulose, while the nanofibrillated cellulose chains act like threads and bind the nanosheets together. The same synergistic effect could be exploited in other materials, the researchers note. For the first time, we investigate the synergistic effect of one-dimensional nanofibrillated cellulose (NFC) and two-dimensional graphene oxide (GO) to facilitate low-cost, mechanically strong hybrid microfibers. Both experimental and molecular dynamics simulations were carried out. Such GO-NFC hybrid microfibers show an elastic modulus of 34.1 GPa, an ultimate tensile strength of 442.4 MPa and a toughness of 4.9 MJ m−3, which outperform among the best GO fibers in literature. This study promotes a new design strategy to create high-performance microfibers for a range of applications.