Self-Planarization of High-Performance Graphene Liquid Crystalline Fibers by Hydration

Abstract

Graphene fibers (GFs) are promising elements for flexible conductors and energy storage devices, while translating the extraordinary properties of individual graphene sheets into the macroscopically assembled 1D structures. We report that a small amount of water addition to the graphene oxide (GO) N -methyl-2-pyrrolidone (NMP) dispersion has significant influences on the mesophase structures and physical properties of wet-spun GFs. Notably, 2 wt % of water successfully hydrates GO flakes in NMP dope to form a stable graphene oxide liquid crystal (GOLC) phase. Furthermore, 4 wt % of water addition causes spontaneous planarization of wet-spun GFs. Motivated from these interesting findings, we develop highly electroconductive and mechanically strong flat GFs by introducing highly crystalline electrochemically exfoliated graphene (EG) in the wet-spinning of NMP-based GOLC fibers. The resultant high-performance hybrid GFs can be sewn on cloth, taking advantage of the mechanical robustness and high flexibility.

Multiscale Structural Modulation of Anisotropic Graphene Framework for Polymer Composites Achieving Highly Efficient Thermal Energy Management

“…[ 19 ] The anisotropic graphene framework can be also readily prepared utilizing the liquid crystal nature of GO, which arises from their intrinsic shape anisotropy and mutual electrostatic‐repulsion, leading to the spontaneous assembly of GO with a long‐range ordered structure in the aqueous dispersion. [ 42–44 ] After air‐drying followed by a graphitization treatment at 2800 °C, Yu et al. embedded the as‐prepared anisotropic graphene framework into the epoxy, and obtained a currently record‐high thermal conductivity of 35.5 W m −1 K −1 for the graphene/polymer composites (19 vol%), giving a specific TCE up to 884% along the preferred direction.…”

Tailored growth of graphene oxide liquid crystals with controlled polymer crystallization in GO-polymer composites

“…[4][5][6][7][8] GO can be easily dispersed in polar solvents, including water, and is known to exhibit liquid crystallinity. [9][10][11][12] Good dispersity and the ability to form LC has enabled GO to be a good candidate as an effective nanofiller compared to other carbon materials. Therefore, one of the most attractive applications of GO is GO-based polymer nanocomposites, where GOs are employed as effective nanofillers enhancing the physical properties of the neat polymer matrix based on its large surface area and functionality.…”

High-Performance Graphene Fibers Enabled by Hydration

“…In addition to using GO aqueous dispersions, it is important to develop GO dispersions based on organic solvents that are more capable of dispersing functional nanomaterials than aqueous media. In this issue of ACS Central Science , Kim and co-workers reported that the addition of a small amount of water to a GO-dispersed organic solvent could effectively enable hydration of GO sheets, 1 thus promoting the formation of a highly stable liquid crystalline GO phase and electrochemically exfoliated graphene (EG) ( Figure 1 ). This method may provide a general and effective strategy to produce high-performance hybrid graphene fibers from GO organic dispersions.…”

“…In contrast, circular-shaped graphene fibers with wrinkled graphene sheets were wet-spun from GO/EG NMP dope without water addition. Reproduced with permission from ref ( 1 ). Copyright 2020 American Chemical Society.…”

“…Unlike the previous strategies to modify GO sheets by increasing aspect the ratio and functional groups, 6 − 8 Kim and co-workers discovered that adding only 2 wt % water to the GO/NMP dispersion could effectively enhance the solubility of the GO sheets. 1 The authors concluded that the hydrated surface of the GO sheets, after introducing water, could serve as an effective intermediate layer to achieve high colloidal stability in NMP. They carefully investigated the formation behaviors of GO liquid crystalline phase in the presence of water.…”