Nanostructure Analysis by Electron Tomography

本研究的目的是澄清复杂的纳米结构，如自组装的嵌段共聚物的微区结构和纳米技术材料中的复合结构，这是从来没有理解的二维图像通过透射电子显微镜（TEM），通过三维观察的电子断层扫描。为此，我们发展和改进了电子层析成像技术。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（P2 VP）组成的四嵌段共聚物。电子断层扫描显示，该聚合物的微区结构是由P2 VP核和PDMS组成的三重同轴圆柱体和PI壳层以六角方式填充在PS基体中。在2003年，我们用电子层析和能量过滤透射电子显微术研究了一种由PS、PI和PDMS组成的3-杂臂星星聚合物。电子断层扫描显示，该星星聚合物形成了复杂形状的横截面的圆柱形微区。除了研究多组分体系外，我们还研究了双组分体系。我们首次观察到PS-b-PI-b-PS三嵌段共聚物的球形微区在BCC晶格中的三维排列以及从球形微区向圆柱形微区的转变。此外，我们澄清了六角穿孔层（HPL）结构，缺陷和晶界结构的PS-b-PI二嵌段共聚物/homoPS共混物，以及纳米复合材料，如陀螺网络结构纳入Pd纳米粒子。我们还开发了三维噪声滤波器（中值滤波器）的三维层析成像数据。

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.