隔离导电复合材料泡沫的非均质结构调控及电磁屏蔽机理研究

Polymer-based composites with electromagnetic functional fillers exhibit the most promising application in electromagnetic shielding due to their adjustable electromagnetic parameter and good processability. However, high contents of electromagnetic filler and serious surface reflection limit its extensive applications in electromagnetic shielding. To overcome the above-mentioned shortcomings, we put forward using structure regulation of the heterogeneous foam to obtain segregated composite with high efficient electromagnetic absorption performance under low filling content. The obtained composite foam is composed of many construction units, which contains wave-transmitting layer, wave-absorbing layer and wave-reflecting layer. This project intends to adjust the overlap structure of electromagnetic functional particles by adsorption of electromagnetic functional particles on the graphene sheets (GNS) surface. Combined with high pressure filter and filler selected covering, the foam composite with segregated structure and controlled distribution of electromagnetic functional particles is to be obtained. Thus the high-absorption electromagnetic shielding composites being able to repeatedly absorb the electromagnetic wave can be prepared. The effects of overlap of filler on the conductivity and electromagnetic shielding for the polymer composites will be revealed. Additionally, by manipulating the pore structure and the segregated layer distribution through covering the polymer particles with NaCl or electromagnetic functional filler, the relationship between electromagnetic shielding parameters and the structure of foam composites can be founded. This study is very important to explore the regularity of electromagnetic shielding of heterogeneous foam composite. It is also conductive to reveal the absorption and reflection mechanism of electromagnetic wave propagation in the heterogeneous foam composites material, which can provide a theoretical basis and method for actual production of high-absorption electromagnetic shielding materials.

聚合物基电磁功能复合材料具有电磁参数可调及加工性能优异等特点，成为最具应用前景的电磁屏蔽材料。然而，较高的电磁粒子填充量及严重的表面反射限制了其在电磁屏蔽中的广泛应用。为此，我们提出通过对具有良好阻抗匹配的泡沫结构进行非均质化调控来构建由众多透波层+吸收层+反射层组成的隔离型低填充/高吸收电磁屏蔽材料。本项目拟采用混杂电磁粒子间的搭接质量来调控各层电磁参数，并结合高压-沥滤和填料选择包覆法实现泡孔结构及隔离区域分布的可控调节，使入射的电磁波“陷”入到泡孔内部，形成具有多次吸收的电磁屏蔽材料。通过混杂填料搭接结构与复合材料电磁参数间的关系研究，探明填料表面搭接形态对复合材料电磁参数及屏蔽效能的影响规律。通过泡孔结构及隔离区域分布调控与电磁屏蔽参数间的关系研究，探索非均质复合材料泡沫的电磁屏蔽机理，揭示电磁波在非均质泡孔材料中的吸收及反射规律，为高吸收型电磁屏蔽复合材料的设计及制备提供新思路。

针对较高的电磁粒子填充量及严重的表面反射限制了聚合物基功能复合材料在电磁屏蔽中的广泛应用问题，本项目提出了通过具有良好阻抗匹配的泡沫结构进行非均质化调控来构建由众多透波层+吸收层+反射层组成的隔离型低填充/高吸收电磁屏蔽材料。首先研究了层状结构电/磁聚合物基复合材料的微结构与电磁屏蔽性能间的关系及其影响规律，结果发现电/磁粒子分布对复合材料的表面阻抗及内部吸收有重要影响，通过合理的微结构调控可实现电磁波在复合材料表面的低反射和内部多次反射+吸收机制，从而有效损耗电磁能。此外，通过在气凝胶中构建结构可控的电/磁多功能网络，制备了一系列具有高效电磁屏蔽及吸收功能的聚合物基复合膜（如多孔纤维素气凝胶、热塑性聚氨酯、三聚氰胺泡沫、聚偏氟乙烯及丝瓜络等），实现了轻质高效的电磁吸收，研究发现泡孔结构对电磁波入射率有决定性的影响，而完整的电/磁网络及填料分布是高效电磁吸收的关键。在此基础上还进行了高效电磁屏蔽性能和人体运动监测的结合探索性研究，获得了一种可长期稳定使用的柔性电子传感器件。另外，结合注塑成型和表面涂覆法研究了可大规模制备的隔离型电屏蔽复合材料（如PLA及纤维素纸）的微结构对其电磁吸收及力学性能间的影响规律，从而成功制备了具有高效电磁屏蔽和良好力学性能的环保型导电聚合物复合材料，为高电磁屏蔽材料制备提供了新思路。本项目还将填料结构调控的思路拓展到了超级电容器、污水处理、柔性传感器件及热管理材料中，通过填料的微结构调控制备出了一系列具有较大能量密度和功能密度的超级电容器材料、可选择性吸收的染料净化剂及兼具高灵敏度和宽检测范围的柔性器件。这些研究为轻质高吸收型电磁屏蔽复合材料、超级电容器及污水净化等方面的应用提供了理论基础和实践经验。