高介电全有机复合薄膜中定向有序纳微阵列结构控制及其与介电性能关联的机制研究

To improve all kinds of properties of engineering dielectrics, it is very crucial to design the composition, multiscale structure and preparation process of materials. In fact, oriented nano-microscale array structure has been paid more attention in this field. In this project, high dielectric permittivity all-organic composite films applied in a high-density energy storage capacitor will be investigated. Namely, the polyvinylidene fluoride (PVDF) and its copolymers with high polarization and high permittivity are blended with the low-permittivity polyolefin (polypropylene). It is expected an oriented nano-microscale array structure of PVDF and its copolymer can be induced in the blending films by employing an alternating current field during the preparation process of the films. We will pay more attention on physical process and influence factors of the oriented nano-microscale array structure formation. We also disclose that the relevant laws between oriented nano-microscale array structure and dielectric permittivity, dielectric loss, breakdown field and electrical displacement in the studied films by analyzing all kinds of results from morphology, experiment and simulation. Dependences of dielectric properties on frequency and temperature and also the dependence of energy storage density and electrical field will be presented. Finally, we will illustrate the principle for forming the oriented nano-microscale array structure and also conclude the mechanism about the effect of the oriented nano-microscale array structure on dielectric properties in the blending films. This work will have a potential driving force for the engineering application of high-permittivity all-organic films.

改善工程电介质性能的关键在于对材料组成、多层次结构以及制备工艺不断创新，设计和控制材料中形成定向有序纳微阵列化结构是提升电介质材料性能前沿研究的热点之一。本项目以高储能密度电容器用高介电全有机复合薄膜为研究对象，提出将极性较强、介电常数较高的聚偏氟乙烯及其共聚物与介电常数较低的聚丙烯等聚烯烃共混，在制备薄膜过程中利用外加电场获得具有定向有序纳微阵列结构复合薄膜。重点研究电场作用下聚偏氟乙烯及其共聚物在复合薄膜中形成有序纳微阵列结构的物理过程及其影响因素，通过电镜等多种表征手段与性能测试和模拟相结合，揭示定向有序纳微阵列结构对复合薄膜介电常数、介电损耗、击穿电场及电位移的影响规律，建立这类复合薄膜介电性能的频率和温度依赖性及其储能密度与电场的依赖关系，查明高介电全有机复合薄膜中定向有序纳微阵列结构的控制原理，归纳复合薄膜中纳微阵列结构对其介电性能影响的机制，为全有机复合薄膜的应用奠定基础。

高性能聚合物介质材料是发展高储能薄膜电容器的关键材料，本项目主要针对全有机介电复合材料结构与性能的关系开展研究，围绕材料组成和多层次结构设计，比较系统的研究了全有机复合材料介电性能的变化规律，揭示了不同聚合物体系与聚偏氟乙烯的可控制备原理。重点研究了聚合物复合电介质介电特性与击穿场强的协同调控的机制，揭示了全有机体系的物性对复合电介质介电性能影响规律，有效改善复合电介质的储能特性，查明不同全有机组分及其结构对复合电介质介电性能的影响机制。具体地说，本项目基本按照研究内容完成各项工作，揭示了共混复合薄膜中定向有序纳微阵列结构形成过程、影响因素和控制机理，掌握了共混复合薄膜中定向有序纳微阵列结构的科学表征方法，建立了基于铁电聚合物有效调控PP和PET等聚合物介电性能和储能密度的科学方法，揭了示共混复合薄膜中定向有序纳微阵列结构对其介电和储能性能影响的机制，为这类材料在电气工程和微电子等领域的应用奠定了基础。