This work describes the application of X-ray ptychography for the inspection of complex assemblies of highly anisotropic nanocrystals embedded in a thick polymer matrix. More specifically, this case deals with CdSe/CdS octapods, with pod length L = 39 ± 2 nm and pod diameter D = 12 ± 2 nm, dispersed in free-standing thick films (24 ± 4 µm) of polymethyl methacrylate and polystyrene, with different molecular weights. Ptychography is the only imaging method available to date that can be used to study architectures made by these types of nanocrystals in thick polymeric films, as any other alternative direct method, such as scanning/transmission electron microscopy, can be definitively ruled out as a result of the large thickness of the free-standing films. The electron density maps of the investigated samples are reconstructed by combining iterative difference map algorithms and a maximum likelihood optimization algorithm. In addition, post image processing techniques are applied to both reduce noise and provide a better visualization of the material morphological details. Through this process, at a final resolution of 27 nm, the reconstructed maps allow us to visualize the intricate network of octapods inside the polymeric matrices.

中文翻译：

---

厚聚合物中自组装 CdSe/CdS 八足形纳米晶的 X 射线叠层模式

这项工作描述了 X 射线叠层照相术在检查嵌入厚聚合物基体中的高度各向异性纳米晶体的复杂组件中的应用。更具体地说，本案例涉及 CdSe/CdS 八足体，其足长 L = 39 ± 2 nm，足直径 D = 12 ± 2 nm，分散在聚甲基丙烯酸甲酯和聚苯乙烯的独立式厚膜 (24 ± 4 µm) 中，具有不同的分子量。叠层照相术是迄今为止唯一可用于研究厚聚合物薄膜中这些类型的纳米晶体所形成的结构的成像方法，因为任何其他替代的直接方法，例如扫描/透射电子显微镜，都可以被明确排除。独立式薄膜的大厚度。通过结合迭代差异图算法和最大似然优化算法来重建所研究样品的电子密度图。此外，还应用后图像处理技术来减少噪声并提供材料形态细节的更好可视化。通过这个过程，最终分辨率为 27 nm，重建的图谱使我们能够可视化聚合物基质内复杂的八足体网络。