基于微孔发泡的隔离型聚合物基电磁屏蔽复合材料及其机理研究

Polymeric electromagnetic shielding composites have important potentialities in the areas of aerospace, military engineering, transportation and electronics, etc. It is technologically difficult and scientific challenging to fabricate the polymeric composites with combined functionalities including lightweight, low filling amount and high electromagnetic interference shielding effectiveness. In this project, the supercritical CO2 microcellular foaming is proposed to introduce microcellular structures into the thermoplastic polyamide elastomer for the reduction of mass density. The hydrogen-bond assembly and steam-assisted molding process are applied to construct the segregated structures for lower percolation threshold, as well as higher conduction loss and internal multiple reflection losses. The electric-magnetic compounding is used to improve the impedance matching and electromagnetic recombination losses. Based on the multi-level structure design, the collaborative modification of the polymeric composites with lightweight and high electromagnetic interference shielding effectiveness at low filling amount would be obtained. The dependences of electromagnetic interference shielding effectiveness on structural regulation and selective distribution of conductive Ti3C2Tx lamellas and magnetic Fe3O4 particles, regulation of microcellular structures and segregated structures will be investigated. The intrinsic conductive “percolation” behaviors and electromagnetic recombination losses of the segregated microcellular composites will be explored. The structure-function relationship of “microcellular structures-segregated structures-shielding effectiveness” will be revealed as well. Furthermore, the electromagnetic interference shielding mechanism would be clarified. Researches above and the obtained results would provide the theoretical foundation and experiment evidence for the design and research of polymeric composites with lightweight, low filling amount and high electromagnetic interference shielding effectiveness.

聚合物基电磁屏蔽复合材料在航空航天、军事工程、交通及电子等领域具有重要的应用前景，如何制备兼具轻质、低填充且高电磁屏蔽效能的聚合物基复合材料是目前亟需解决的技术难点和科学问题。本项目拟从多层次结构设计出发，通过超临界CO2微孔发泡在热塑性尼龙弹性体珠粒中引入微孔结构以降低密度，借助氢键组装和蒸汽辅助模压成型构筑隔离结构以降低逾渗阈值，增强电导损耗和内部多重反射损耗，利用电磁复合提高阻抗匹配和电磁复合损耗，实现低填充下聚合物基复合材料轻质和高电磁屏蔽效能的协同改性。研究导电Ti3C2Tx片层与磁性Fe3O4颗粒的结构调控和选择性分布、微孔结构与隔离结构的调控对电磁屏蔽效能的影响规律，探究隔离型复合微孔材料中导电“逾渗”行为的本质和电磁复合损耗机制，揭示“微孔结构-隔离结构-屏蔽效能”的构效关系，明晰电磁屏蔽机理，为轻质、低填充且高电磁屏蔽效能聚合物基复合材料的设计研发提供理论依据和实验基础。

聚合物基电磁屏蔽复合材料的研制和开发是目前功能材料研究领域的热点。尤其在航空航天、军事工程、交通及电子等领域要求电磁屏蔽材料不仅轻质，且应具有高电磁屏蔽效能和力学性能，而复合材料的性能主要取决于材料内部的多层次结构。本项目以高性能热塑性尼龙弹性体为聚合物基体，采用超临界CO2微孔发泡、氢键组装和模压成型相结合的方法制备出兼具轻质、低填料用量且高电磁屏蔽效能的隔离型聚合物基复合微孔材料。结果表明，在聚合物基复合材料中同时构筑微孔结构和隔离结构能显著降低材料密度和导电逾渗阈值，增强电磁波吸收损耗和总电磁屏蔽效能。通过调控导电粒子的选择性分布、微孔结构和隔离结构可实现低填料用量下复合材料轻质和高电磁屏蔽效能的协同改性，所得复合材料的电磁屏蔽机制以电磁波吸收损耗为主导。探明了隔离型聚合物基复合微孔材料的导电“逾渗”行为，建立了“微孔结构-隔离结构-屏蔽效能”的构效关系，明晰了电磁屏蔽机理，为轻质、低填料用量且高电磁屏蔽效能聚合物基复合材料的设计研发提供理论支撑和实验基础。在此基础上，拓展了柔性高强层级结构电磁屏蔽复合薄膜和多功能可穿戴电磁屏蔽复合材料的制备研究，以满足航空航天、军事工程、人工智能和可穿戴电子设备等领域对高性能和多功能柔性电磁屏蔽材料的应用需求。