链中构筑微导单元的聚酰亚胺的设计合成与介电性能研究

The dielectric properties of a material are strongly dependent on the charge storage ability of its inner molecules under applied electric field. Based on this consideration and the principle of percolation theory, microcapacitor model and electron donor-acceptor theory, we propose a bran-new idea of designing polyimides with high permittivity by introducing electron donor-acceptor pairs into the polymer chains in a non-continuous manner with the purpose of forming massive micro-conductors in molecular level. It is believed that a micro-conductor will function as a microcapacitor when an electric field was applied. Accordingly, a supercapacitor will be formed in the bulk of the material due to the accumulation effect of numerous individual microcapacitors, consequently leading to a significant enhancement in the dielectric permittivity of the material. In the proposed work, the influence of the structure, concentration and spatial distribution of the electron donor-acceptor pairs in the polyimide chains on the electric properties, especially the dielectric properties will be thoroughly investigated. Meanwhile, the charge transfer process and mechanism between the electron donor-acceptor pairs will also be studied based on quantum molecular simulation. Eventually, based on the results obtained from the above work, the structure-property relationships of the material are expected to be established. The accessibility of the proposed idea has been proved in our preliminary work. The current work will make contribution to the research area of polymeric energy storage materials by accumulating new fundamental knowledge and practical experience, and with great prospect of opening a new route for the exploration of polymeric high dielectric materials.

材料的介电性能取决于其内部分子在电场作用下对于电荷的储存能力。基于此原理，结合渗流阈值理论、微电容器模型和电子给体受体的相关理论研究，本课题提出了一个全新的研究构想，即通过在聚酰亚胺分子链内引入嵌段分布的由电子给体受体对构成的微导体单元来制备高介电聚酰亚胺材料的研究思路。在外电场作用下，每一个微导单元都可以作为一个可极化单元形成一个微小的电容器，大量微电容器的累积构成一个超级电容器，使得材料的介电性能得到大幅度的提高。研究将主要关注于电子给体受体基团的结构、含量、空间分布对材料电性能，特别是介电性能的影响。采用分子模拟的方法分析电荷在电子给体受体之间的传递过程和机理，建立材料结构与性能的关系。初期的探索研究已证实了该构想的可操作性。本项目的实施可以为聚合物基储能材料的研究积累理论和实验经验，以期开拓出一条研究聚合物基高介电材料的新路线。

材料的介电性能取决于其内部分子在电场作用下对于电荷的储存能力，在聚酰亚胺分子链内引入嵌段分布的由电子给体受体对构成的微导体单元可显著提高材料对电场的响应能力。在外电场作用下，每一个微导单元都可以作为一个可极化单元形成一个微小的电容器，大量微电容器构成一个超级电容器，使得材料的介电性能得到大幅度提高。本项目在前期工作基础上，采用分子模拟的方法分析电荷在电子给受体之间的传递过程和机理，建立材料结构与性能的关系，通过设计电子给受体基团的结构、含量、空间分布和在体系内引入纳米碳材料等方法，提升了材料的介电性能。此研究为进一步阐明高介电常数产生机理、为制备高介电常数薄膜材料提供理论依据。