Quantitative Imaging of Tg in Block Copolymers by Low-Angle Annular Dark-Field Scanning Transmission Electron Microscopy
Quantitative Imaging of Tg in Block Copolymers by Low-Angle Annular Dark-Field Scanning Transmission Electron Microscopy
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DOI：
10.1021/ma4014934
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发表时间：
2013-10
期刊：
影响因子：
5.5
通讯作者：
R. Aso;H. Kurata;Takeshi Namikoshi;T. Hashimoto;S. Kuo;F. Chang;H. Hasegawa;M. Tsujimoto;M. Takano;S. Isoda
中科院分区：
文献类型：
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作者：
R. Aso;H. Kurata;Takeshi Namikoshi;T. Hashimoto;S. Kuo;F. Chang;H. Hasegawa;M. Tsujimoto;M. Takano;S. Isoda
由于聚合物材料的散射对比度较弱，使用传统的透射电子显微镜（TEM）观察其纳米级结构通常是困难的。为了在没有任何染色的情况下产生定量图像对比度，研究了低角度环形暗场扫描透射电子显微镜（LAADF-STEM）观察嵌段共聚物精细结构的适用性。LAADF-STEM图像显示了嵌段共聚物的微相分离形态，具有高的S/N对比度，取决于非染色的固有密度差。我们发现，图像对比度的温度依赖性显示了一个扭结周围的玻璃化转变的组成相，从中可以估计玻璃化转变温度和热膨胀系数在纳米级。这表明LAADF-STEM成像是定量成像聚合物纳米级相的有效工具。
It is often difficult to observe nanoscale structures of polymeric materials using conventional transmission electron microscopy (TEM) because of their weak scattering contrast. To produce quantitative image contrast without any staining, low-angle annular dark-field scanning transmission electron microscopy (LAADF-STEM) was studied for its applicability for observing fine structures in block copolymers. The LAADF-STEM images displayed microphase-separated morphologies of block copolymers with high S/N contrast depending on the intrinsic density difference because of nonstaining. We found that the temperature dependence of the image contrast showed a kink around the glass-transition of the constituent phase, from which one can estimate glass transition temperatures and thermal expansion coefficients at nanoscale. This indicates that the LAADF-STEM imaging is an effective tool to quantitatively image nanoscale phases of polymers.