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Direct observation of polymer network structure by TEM

通过TEM直接观察聚合物网络结构

基本信息

批准号：
13450392
负责人：
KOHJIYA Shinzo
金额：
$ 8.7万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450392/
关键词：
Polymer network TEM Network structure 化学ゲル物理ゲル

项目摘要

Polymer network systems are a typical amorphous system, and many structural studies on them have been conducted by scattering techniques using photon, X-ray and neutron. However, the discussions are more or less limited on long-distance orderings, and the detailed structures are still to be elucidated.This study aimed to conduct direct observations of polymer network structures by transmission electron microscopy (TEM), which was very ambitious trial because such observations were limited on highly crystalline polymers, never on amorphous ones.As samples for the TEM observation, poly(siloxane) networks, those introduced phenyl groups for improving electron-beam resistance, liquid crystalline elastomers containing aromatic mesogens, poly(oxyethylene) networks doped with inorganic salts, and ionic polyether elastomers. Using microtome, which was purchased by this funding, the ultrathin films of these polymer samples (thickness ; 100-300 nm) were prepared at room temperature or at lower temperatures (liquid nitrogen temperature or Dry-ice temperature).On these thin samples TEM measurements by cryo-techniques and/or staining technique using ruthenium oxide were carried out for many times. However, all trials failed to directly observe the network structure. We managed to observe crystalline emages of natural rubber under extension by TEM together with the electron diffraction patterns, and crystalline lamellae of polyethers. However, these are all crystalline structures formed in the amorphous matrix, not the network structure. Taking account that phenyl groups were not effective, we have to consider preparing much more resistant polymer networks or figuring out another methods of TEM observation far our initial purpose.

聚合物网络体系是典型的非晶态体系，人们利用光子、X射线和中子的散射技术对其进行了许多结构研究。然而，讨论或多或少局限于长距离有序，详细结构仍有待阐明。本研究旨在通过透射电子显微镜（TEM）对聚合物网络结构进行直接观察，这是一项非常雄心勃勃的尝试，因为这种观察仅限于高度结晶的聚合物，而不是无定形聚合物。作为TEM观察的样品，聚（硅氧烷）网络，那些引入苯基的聚硅氧烷网络改善电子束耐受性、含有芳香族介晶的液晶弹性体、掺杂无机盐的聚氧乙烯网络和离子聚醚弹性体。使用本基金购买的切片机，在室温或较低温度（液氮温度或干冰温度）下制备这些聚合物样品的超薄膜（厚度；100-300 nm）。对这些薄样品通过低温技术和/或氧化钌染色技术进行多次TEM测量。然而，所有试验都未能直接观察网络结构。我们成功地通过 TEM 观察了天然橡胶在拉伸下的结晶图像以及电子衍射图，以及聚醚的结晶片层。然而，这些都是在非晶基体中形成的晶体结构，而不是网络结构。考虑到苯基无效，我们必须考虑制备更耐用的聚合物网络或找出另一种 TEM 观察方法，以达到我们最初的目的。