Mechanical property enhancement of high conductive reduced graphene oxide fiber by a small loading of polydopamine

Improving the interaction of individual reduced graphene oxide sheet is an effective way to enhance the mechanical property of reduced graphene oxide fiber. In this study, to enhance the interaction forces of graphene sheets, large-sized graphene oxide sheets were used to assemble graphene fiber, and dopamine was mixed with the graphene oxide spinning drop. During the wet-spinning procedure, polydopamine was formed by polymerizing. It is found that such obtained composite fiber shows enhanced tensile strength (increased from 314 MPa to 527 MPa) and increased toughness (increased from 3.5 MJ m⁻³ to 12.9 MJ m⁻³) compared with pure reduced graphene oxide fiber. Fourier-transform infrared spectra, Raman spectra and x-ray photoelectron spectroscopy were performed to characterize the interaction between reduced graphene oxide sheets and polydopamine, and a possible enhancement mechanism of C-N bonds formation was proposed. It is suggested that this newly formed C−N bonds can not only enhance the tensile strength, but also increase the elongation simultaneously. Additionally, the graphene fiber remains great electrical conductivity (33 100 s m⁻¹) since the conductive network can be maintained. (paper)