如何讲好聚合物的导电性(Ⅰ)——一维结构材料一般不是电导体

How to Teach the Conductivity of Polymer(Ⅰ)—The Materials with One-dimensional Structure Are Nonconductive

一般来说,由共价单键连接起来的高分子链已经没有了能够自由运动的电子(载流子),加上主要靠范德华力堆砌的聚合物分子之间距离较大,电子云交叠差,载流子的离域运动极为困难,因此聚合物通常是绝缘体。但是,即使像聚乙炔那样具有π键结构、其主链每个碳原子上带有一个导电电子的聚合物也不能导电,这是因为高分子链是一维体系,空间结构维度性决定了其导电性。一维结构的材料具有派尔斯不稳定性,使得即使每个原子都有导电的价电子,它也不会(在低温下)导电,这是一条普遍的物理规律。

Generally, polymer is an insulator due to that polymer chain connected by the covalent single bond does not contain free electrons （carriers）. In addition, macromolecular chains are coherent with each other through Van der Waals forces, and hence have large distance between them resulting in poor electron clouds overlapping, so that it is much difficult for carriers＇ delocalization. Likewise, polymer even with π-bond and conductive electrons, such as polyacetylene, is nonconductive as well. The reason is the one-dimensional chain structure in which Peierls instability occurs.