Lignin, the most abundant aromatic biopolymer on the earth, is considered as a sustainable carbon fiber precursor. However, lignin-based carbon fibers face great challenges in the fiber spinning and thermal stabilization due to the complex structure of lignin. In this work, lignosulfonate-acrylonitrile-itaconic acid (LS-AN-IA) terpolymer with excellent spinnability was prepared as a novel precursor for carbon fibers, and the thermal properties and thermal stabilization of this precursor were studied. The introduced itaconic acid (IA) comonomer was found to play an important role in improving the thermal properties and promoting the thermal stabilization. The hindering effect of LS on the cyclization reaction of nitrile groups was overcome by the IA comonomer through changing free-radical reaction mechanism to an ionic one. The thermal stabilization of the LS-AN-IA terpolymer precursor fibers could be carried out at a lower temperature and required a shorter time, which helped to reduce the energy and time consumption. Carbon fibers with tensile strength and tensile modulus of 1.74 GPa and 210 GPa, respectively, were obtained from the LS-AN-IA terpolymer.

木质素是地球上最丰富的芳香生物聚合物，被认为是可持续的碳纤维前体。然而，由于木质素的复杂结构，木质素基碳纤维在纤维纺丝和热稳定性方面面临巨大挑战。在这项工作中，制备了具有优异可纺性的木质素磺酸盐-丙烯腈-衣康酸（LS-AN-IA）三元共聚物作为新型的碳纤维前驱体，并研究了该前驱体的热性能和热稳定性。发现引入的衣康酸（IA）共聚单体在改善热性能和促进热稳定性中起重要作用。IA共聚单体通过将自由基反应机理改变为离子反应机理，克服了LS对腈基环化反应的阻碍作用。LS-AN-IA三元共聚物前体纤维的热稳定化可以在较低的温度下进行，所需的时间更短，这有助于减少能耗和时间消耗。由LS-AN-IA三元共聚物获得的抗张强度和抗张模量分别为1.74 GPa和210 GPa的碳纤维。