Graphene Stable Dispersion Driven by Noncovalent Functionalization and Graphene Fibers Preparation.

Graphene fibers (GFs) formed via graphene self-assembly are promising one-dimensional carbon-based functional materials due to their lightweight flexibility and excellent electrical conductivity. However, the instability of graphene self-assembly in liquid-phase systems currently limits GF production to wet-spinning processes using graphene oxide precursors. To address this critical challenge, this work employs a noncovalent interaction-driven strategy for graphene stabilization. The stable dispersion mechanisms of different dispersants in the N,N-dimethylformamide solvent environment with strong polarity for graphene-polyacrylonitrile composite systems were elucidated. Meanwhile, the interplay between dispersant molecular configurations and interfacial interactions on the structure and properties of GFs was revealed. Molecular dynamics simulations combined with comprehensive spectroscopic characterizations, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, reveal that the cationic and anionic dispersants exhibit weak electrostatic interactions and poor diffusion, failing to prevent graphene aggregation in the PAN@DMF system. In contrast, zwitterionic achieves superior dispersion, enabling stable graphene dispersion in liquids. Synergistic amine-carboxyl interactions in CAB dispersant induce dense graphene stacking structures, effectively inhibiting interfacial slippage. The carboxyl groups in the CAB molecule form hydrogen bonds or strong dipole-dipole interactions with the nitrile groups in the PAN molecule, thereby forming a bridged structure. Eventually, graphene fibers exhibit a remarkable tensile strength of 152 ± 5 MPa and a Young's modulus of 225 ± 8 GPa. Furthermore, wide-angle X-ray scattering and small-angle X-ray scattering analyses demonstrate that fibers prepared via this noncovalent route possess a highly ordered porous structure oriented along the fiber axis. This work provides a scalable and efficient route for the direct fabrication of high-performance graphene fibers, bypassing the traditional graphene oxide route and offering significant insights into interfacial engineering for carbonaceous materials.