碳纳米管在PVDF/PA11共混物界面强化增容和调控、及协同介电增强机理研究

The study of functionalization and distribution of nano conductive fillers, and the interfacial compatibilization and controlling of polymer blends for nanocomposites based on polymer blend and nano filler is the basic scientific problem of high dielectric materials with reasonable structures and controllable performances. In this project, inspired by the non-covalent interaction between carbon nanotube and ionic liquid, inductive polar crystal of PVDF, and in situ compatibilization of maleic anhydride, a series of novel poly(methyl methacrylate-co-maleic anhydride) containing ionic liquids moiety would be designed, and used to in situ functionalize carbon nanotube. The impact of copolymer compatibilizing effect, and the corresponding thermodynamic and kinetic factors on distribution of carbon nanotubes at interfaces of co-continuous PVDF/PA11 blends would be investigated during the processes of heating and melt cooling. Furthermore, the effects of different chain segments of copolymers on interfacial chain entanglements, in situ intermolecular reaction, inductive polar crystal of PVDF, and interface reinforcement would be studied. The regularities of charge storage and stability of space charge and dipole across the interfaces and polymer matrix of composites should be investigated via detecting dielectric properties of corresponding microstructures of composites. The mechanism of high dielectric constant, low dielectric loss and low percolation threshold of composites would be revealed. The synergistic mechanism of space charge and dipole on dielectric reinforcement of composites should be revealed. For further, a new theory model of interfacial controlling and dielectric reinforcement for composites based on polymer blend and nano filler should be provided.

聚合物共混物/纳米导电填料复合高介电体系的纳米填料修饰与分布、共混物界面增容和调控研究是介电高性能化的基本科学问题。本项目基于离子液体与碳纳米管的非共价键作用及诱导聚偏氟乙烯（PVDF）极性晶体作用、马来酸酐原位反应增容作用，拟利用含离子液体基元的甲基丙烯酸甲酯-马来酸酐共聚物原位修饰碳纳米管，在复合物受热熔融及熔体冷却过程中，研究共聚物增容作用及相应的热力学和动力学因素对碳纳米管引入PVDF与聚酰胺11（PA11）不相容共混物双连续相界面处的作用机制。进一步考察共聚物不同结构分子链段对共混物界面分子链缠结、原位反应增容、诱导PVDF极性晶体及界面构筑的影响。通过微观结构的介电行为示踪作用，认识空间电荷和偶极在构筑的界面及本体相的电荷储存能力和稳定性的规律，从而揭示高介电常数、低介电损耗和低渗流阈值的产生机制，揭示空间电荷和偶极协同介电增强机理，发展新的复合体系界面调控及介电增强理论。

近年来，随着电器电子及新型半导体技术的的发展，具有高介电常数的电介质复合材料在多元化电子器件上发挥着越来越重要的作用，而如何在降低电介质复合材料填料填充量的同时提高其介电常数是目前研究的重点及难点。本课题基于热力学及动力学角度，从结构调控、多元填料选择、机理研究、模型构建等方面展开研究思路，设计制备了一系列PA基(PA/PVDF、PA/EVA-GMA)复合材料，通过改变基体共混比例、定向分散填料、离子液体共聚物调控相界面结构及定向迁移填料、掺杂多元种类填料等方法研究了相结构演化、导电与介电填料掺杂等对PA基共混复合体系介电增强的影响，同时研究了其对PA基复合材料聚集态结构及相结构演变的影响，分析共混复合体系中相界面结构调控与协同增强介电性能之间的作用及机理。. 通过研究发现，在PA/PVDF/MWCNTs复合体系中，当PA与PVDF的共混比例为30:70时，两相共连续相最完善且MWCNTs分散在PVDF相中，当将P[MAA-BA-(VEIm)Br]离子液体共聚物引入到PA/PVDF/MWCNTs复合体系中后，当PA:PVDF的共混比例为40:60时，两相之间共连续结构最为完善，说明处于相界面处的P[MAA-BA-(VEIm)Br]共聚物能够起到增塑作用，增强了分子链运动能力，减小了相界面界面张力，从而使得PA与PVDF在共混比例为40:60时即出现了双连续结构，同时研究发现，PA/PVDF/MWCNTs/PILs复合材料的电导率均高于PA/PVDF/MWCNTs复合材料的电导率。另外，通过向PA/EVA-GMA共混物中掺杂高介电常数填料BaTiO3和高导电填料MWCNTs，发现当向PA/EVA-GMA/MWCNTs体系中引入BaTiO3后，其介电常数大幅度增强，如PA/EVA-GMA/BT/4MWCNTs的介电常数相比于PA/EVA-GMA/4MWCNTs增高了118%，但其介电损耗仅增加了0.07。本课题研究表明通过相结构调控与掺杂多元填料等研究方法可强化界面增容及协同增强介电行为。. 综上所述，本课题实现了PA基共混复合体系界面强化增容和调控及协同介电增强机理研究，自课题实施以来，共计发表SCI论文12篇，ESCI论文1篇，取得了预期的研究成果，并为后续研究工作提供了基础。