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，阐明纳米技术材料中复杂的纳米结构，如嵌段共聚物的自组装微区结构和纳米技术材料中的复合结构，这些结构是通过电子断层扫描获得的二维图像无法理解的。为此，我们发展和改进了电子断层扫描技术。2002年，我们研究了由雅典大学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。电子断层扫描显示，该聚合物的微区结构为三同轴柱状的P2VP核和聚二甲基硅氧烷(PDMS)和聚酰亚胺(PI)壳层，在PS中呈六边形排列。2003年，我们用电子断层扫描和能量过滤电子显微镜相结合的方法研究了由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区。除了多组分体系的研究外，我们还研究了双组分体系。我们首次观察到PS-b-PI-b-PS三嵌段共聚物的体心立方晶格中球形微区的三维排列以及从球形微区到柱状微区的转变。此外，我们还阐明了PS-b-PI两嵌段共聚物/HomoPS共混物中的六角穿孔层(HPL)结构、缺陷和晶界结构，以及含有Pd纳米粒子的陀螺体网络结构等纳米复合材料。我们还针对3D断层扫描数据开发了3D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.