Lignin valorization is significantly hindered by the intrinsic heterogeneity of its complex structures and variability of biomass feedstocks. Fractionation of lignin can overcome these challenges by producing functionally distinct lignin cuts that can be further tailored to end products. Herein, lignin was extracted and depolymerized from poplar by the co-solvent enhanced lignocellulosic fractionation method with renewable THF to obtain CELF lignin. Several solvents were screened to separate soluble and insoluble fractions from the parent CELF lignin. The ethanol soluble portion was then fractionated into different molecular weight cuts via sequential precipitation of the lignin by reducing the concentration of THF. The physicochemical structures of different CELF lignin cuts were elucidated by GPC and NMR techniques. These results suggest that CELF lignin cuts with lower molecular weight contain progressively higher phenolic and carboxylic acid OH groups, which can be more suitable as green antioxidants than the parent lignin.

木质素的价码化因其复杂结构的内在异质性和生物质原料的可变性而受到显着阻碍。木质素的分级分离可以通过生产功能独特的木质素切块来克服这些挑战，这些切块可以进一步针对最终产品进行定制。在此，通过与可再生THF的共溶剂增强木质纤维素分级分离法从杨树中提取木质素并解聚，从而获得CELF木质素。筛选了几种溶剂以从母体CELF木质素中分离出可溶和不可溶的级分。然后，通过降低THF的浓度，通过依次沉淀木质素，将可溶于乙醇的部分分馏成不同的分子量馏分。通过GPC和NMR技术阐明了不同CELF木质素切块的理化结构。