Nanostructure Analysis by Electron Tomography

本研究的目的是通过电子断层扫描的三维观察来阐明纳米材料中复杂的纳米结构，如嵌段共聚物的自组装微畴结构和复合结构，这些结构在透射电子显微镜（TEM）获得的二维图像中从未被理解。为此，我们发展和改进了电子断层扫描技术。2002年，我们研究了雅典大学Hadjichristidis教授提供的由聚苯乙烯（PS）、聚异戊二烯（PI）、聚二甲基硅氧烷（PDMS）和聚2-乙烯基吡啶（P2VP）组成的四嵌段四元聚合物。电子层析成像结果表明，该聚合物的微畴结构为P2VP核的三同轴圆柱体，PDMS和PI壳在PS矩阵中呈六边形排列。2003年，我们利用联合电子断层扫描和能量滤波透射电镜研究了由PS、PI和PDMS组成的3-Miktoarm星形聚合物。电子断层扫描显示，星形聚合物形成了具有复杂截面的圆柱形微畴。除了研究多组分系统外，我们还研究了双组分系统。我们首先观察到PS-b-PI-b-PS三嵌段共聚物在BCC晶格中球形微畴的三维排列，以及它从球形微畴到圆柱形微畴的转变。此外，我们还澄清了PS-b-PI二嵌段共聚物/homoPS共混物中的六方孔层（HPL）结构、缺陷和晶界结构，以及包含Pd非颗粒的陀螺网络结构等纳米复合材料。我们还开发了三维层析成像数据的三维噪声滤波器（中值滤波器）。

The aim of this study was to clarify the complex nanostructures such as self-assembled microdomain structures of block copolymers and composite structures in nanotechnology materials, which had never been understood from the two-dimensional images obtained by transmission electron microscopy (TEM), by means of three-dimensional observation by electron tomography. For such a purpose we developed and improved the techniques in electron tomography. In 2002, we investigated a tetrablock quaterpolymers consisting of polystyrene (PS), polyisoprene (PI), poly(dimethyl siloxane) (PDMS) and poly(2-vinyl pyridine)(P2VP) provided by Prof. Hadjichristidis in University of Athens. Electron tomography revealed that the micro-domain structure of this polymer had the triple-coaxial cylinders of P2VP core and PDMS and PI shells packed hexagonally in PS matrix. In 2003, we investigated a 3-Miktoarm star polymer consisting of PS, PI and PDMS by using combined electron tomography and energy-filtering TEM. Electron tomography revealed that the star polymer formed cylindrical microdomains with complex-shaped cross-sections. In addition to the study of multicomponent systems, we also investigated two-component systems. We first observed 3D arrangement of spherical microdomains in BCC lattice for a PS-b-PI-b-PS triblock copolymer as well as its transition from spherical microdomains to cylindrical microdomains. Furthermore, we clarified the hexagonally perforated layer (HPL) structure, defects and grain boundary structures in PS-b-PI diblock copolymer/homoPS blends as well as nano-composites such as Gyroid network structures incorporating Pd nonoparticles. We also developed 3D noise filter (median filter) for the 3D tomography data.