The structural characterization of epoxy resins is essential to improve the understanding on their structure–property relationship for promising high-performance applications. Among all analytical techniques, scanning transmission electron microscopy–electron energy-loss spectroscopy (STEM–EELS) is a powerful tool for probing the chemical and structural information of various materials at a high spatial resolution. However, for sensitive materials, such as epoxy resins, the structural damage induced by electron-beam irradiation limits the spatial resolution in the STEM–EELS analysis. In this study, we demonstrated the extraction of the intrinsic features and structural characteristics of epoxy resins by STEM–EELS under electron doses below 1 e/Å at room temperature. The reliability of the STEM–EELS analysis was confirmed by X-ray absorption spectroscopy and spectrum simulation as low- or non-damaged reference data. The investigation of the dependence of the epoxy resin on the electron dose and exposure time revealed the structural degradation associated with electron-beam irradiation, exploring the prospect of EELS for examining epoxy resin at low doses. Furthermore, the degradation mechanisms in the epoxy resin owing to electron-beam irradiation were revealed. These findings can promote the structural characterization of epoxy-resin-based composites and other soft materials.

中文翻译：

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用扫描透射电子显微镜-电子能量损失光谱法对环氧树脂进行微观化学表征

环氧树脂的结构表征对于提高对其结构-性能关系的理解对于有前景的高性能应用至关重要。在所有分析技术中，扫描透射电子显微镜-电子能量损失光谱（STEM-EELS）是在高空间分辨率下探测各种材料的化学和结构信息的强大工具。然而，对于环氧树脂等敏感材料，电子束辐照引起的结构损伤限制了 STEM-EELS 分析的空间分辨率。在这项研究中，我们展示了在室温下电子剂量低于 1 e/Å 的情况下，通过 STEM-EELS 提取环氧树脂的固有特征和结构特征。 STEM-EELS 分析的可靠性通过 X 射线吸收光谱和光谱模拟作为低损坏或无损坏的参考数据得到证实。对环氧树脂对电子剂量和曝光时间依赖性的研究揭示了与电子束辐照相关的结构降解，探索了 EELS 在低剂量下检查环氧树脂的前景。此外，还揭示了电子束照射引起的环氧树脂降解机制。这些发现可以促进环氧树脂基复合材料和其他软材料的结构表征。