Superior strength and toughness of graphene/chitosan fibers reinforced by interfacial complexation

Graphene fibers have been fabricated by wet spinning, in which interfacial interactions including hydrogen bond, ionic bond, covalent bond and pi-pi interaction were usually constructed to achieve effective translation of the extraordinary properties inherent in graphene microscopic building blocks to macroscopic bulk materials. However, the interactions would induce the aggregation of graphene oxide (GO) spinning dope, leading to the local inhomogeneity and deteriorating mobility which was unfavorable for the translation of GO inherent performance. In order to overcome the contradiction, an interfacial polyelectrolyte complexation (IPC) spinning not involving in the usage of organic solvents was proposed to in-situ build a hierarchical assembly structure of well-ordered GO sheets and chitosan molecules by mimicking natural nacre. After partial reduction of GO fibers using HI, strong and tough graphene fibers with tensile strength of 875.5 MPa and toughness of 17.85 MJ/m(3) were obtained due to strong ionic bond and hydrogen bond interactions between rGO and chitosan. Molecular dynamics simulation revealed the fracture mechanism of the graphene fibers that was the slippage of rGO sheets and chitosan molecules accompanied by the breaking and reforming of interfacial bonds. Combing the considerable electrical conductivity, the fibers exhibited a promising application potential as wearable electronics and conductors.