Synthesis of Lignin-Functionalized Graphene Oxide and Insight into Its Reinforcement Mechanism for Gel-Spun Polyacrylonitrile Fibers

Hydrophobic lignin and hydrophilic PAN show poor compatibility, degrading gel-spun PAN fibers’ mechanical performance and limiting textile processing. To resolve this compatibility issue and optimize the mechanical properties of fibers, this study synthesized lignin-graft-graphene oxide (GL) via a two-step modification strategy. The strategy involves succinic anhydride-mediated succinylation of lignin to introduce hydrophilic groups, followed by Steglich esterification to achieve covalent bonding with monolayer graphene oxide. GL was incorporated into the PAN matrix at loadings of 0–5% to fabricate gel-spun composite fibers. The 4% GL/PAN fiber had optimal performance, with tensile strength and Young’s modulus increasing by 24.25% and 41.18% versus the neat PAN fiber. This enhancement is attributed to the ability of GL to promote the order of polymer molecular chains. MD simulation validated this mechanism at the molecular scale. This work provides a promising approach for the preparation of high-performance PAN-based composite fibers.