Cellulose has been developed as an alternative to petrochemical materials. By comparison with refined nanofibers (RCNFs), lignocellulose nanofibers (LCNFs) show particular promise because it is produced from biomass using only mild pretreatment. The mechanical properties of LCNFs depend on the contained lignin. However, the microscopic location of the lignin contained in LCNFs has not been determined. Thus, we developed two methods to detect and visualize lignin. One uses a scanning transmission electron microscope (STEM) equipped with an energy dispersive X-ray spectroscopy detector. The other method uses an atomic force microscope (AFM) equipped with a cantilever coated with an aromatic molecule. Both methods revealed that the lignin in LCNFs covers a thin cellulose fiber and is precipitated in a grained structure. In particular, the AFM system was able to determine the nanoscopic location of lignin-rich areas. The present study establishes a strong tool for analyzing the characteristics of lignin-containing materials.

Graphical abstract

中文翻译：

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通过扫描透射电子显微镜和原子力显微镜对纤维素纳米纤维进行纳米木质素测绘

纤维素已被开发作为石化材料的替代品。与精制纳米纤维（RCNF）相比，木质纤维素纳米纤维（LCNF）显示出特别的前景，因为它是由生物质仅经过温和预处理而生产的。LCNF 的机械性能取决于所含的木质素。然而，LCNF 中所含木质素的微观位置尚未确定。因此，我们开发了两种检测和可视化木质素的方法。一种使用配备能量色散 X 射线光谱探测器的扫描透射电子显微镜 (STEM)。另一种方法使用配备有涂有芳香分子的悬臂的原子力显微镜（AFM）。两种方法都表明，LCNF 中的木质素覆盖了薄纤维素纤维，并以颗粒结构沉淀。特别是，AFM 系统能够确定富含木质素区域的纳米级位置。本研究建立了分析含木质素材料特性的强大工具。

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