高导热电绝缘液晶环氧基复合材料的制备及导热机理研究

The main objective of this project is to solve the problems exsited in the preparation process of thermally conductive and electrically insulating composites，such as low thermal conductivity, dispersion difficulty of thermally conductive fillers and poor interface compatibility between components. The intrinsic thermally conductive liquid crystal epoxy (LCE) resins are synthesized by the rational molecular design. Large-scale fabrication of high thermally conductive boron nitride (BN) nanosheets are carried out by low cost liquid exfoliation techniques. The LCE-based composites with high thermal conductivity and excellent electrical insulation are prepared by exploiting the synergistic effect of LCE and BN nanosheets since both of the components have their own unique properites. For example, LCE possesses the intrinsic thermal conductivity, BN nanosheets possess high thermal conductivity, large specific surface and excellent electrical insulation, etc. The potential impact of the LCE matrix, BN fillers, and interface interaction on composites will be systematically investigated, this will help to reveal the relationship between microstructure and thermally conductive properties, optimize the properties and improve the synergistic effect mechanism and thermal conduction theory of composites. In summary, this study not only raise important theoretical value, it also demonstrates some commercial value as the described technologies are potential to be industrialized, leading to the development of the new generation high performance composites.

本项目以解决目前导热绝缘复合材料制备过程中存在的热导率低、导热填料分散困难及界面相容性差等问题的研究为主要目标。通过对液晶环氧的分子结构设计、氮化硼粉体的低成本液相剥离技术研究，实现液晶环氧的合成和氮化硼纳米片的宏量制备。利用液晶环氧的本征导热，氮化硼纳米片的高导热、高比表面积和高绝缘等特征，通过液晶环氧与氮化硼纳米片协同增强导热机理制备出高导热电绝缘的液晶环氧基复合材料。系统研究基体树脂、氮化硼纳米片及界面相互作用对复合材料导热及电绝缘性能的影响，揭示复合材料微观结构与导热性能之间的内在联系，最终实现高导热电绝缘复合材料综合性能的优化，完善复合材料的协同作用机理和宏观热传导理论。项目的研究不仅在导热绝缘复合材料的研究上具有重要的理论价值，而且在工业化制备上具有一定的应用前景，为新一代高性能复合材料的设计提供实验与理论借鉴。

针对目前导热绝缘复合材料制备过程中存在的热导率低，难以满足目前散热需求、导热填料分散困难及界面相容性差等问题。本项目通过对树脂基体的成功合成设计、发展了导热粉体的制备和改性方法，实现导热填料在高分子基体中良好分散和界面相容性，主要成果包括：（1）通过合成不同类型的液晶环氧的对比研究，成功地制备了一种高导热的联苯型液晶环氧，导热系数达到0.53W/m•K。（2）创造性地提出一种利用熔融碱和超声相结合的剥离技术制备六方氮化硼纳米片的方法，3 nm左右的氮化硼纳米片产率达18%，实现宏量制备氮化硼纳米片。（3）对氮化硼纳米与高分子材料复合的制备方法和性能进行了系统研究，得到了数种综合性能优异的高导热聚合物基复合材料，且最高导热系数达到近10 W/m•K同时保持优异的电绝缘性能。通过本项目的实施，丰富和发展了高导热电绝缘聚合物基复合材料的复合理论, 建立了高导热电绝缘聚合物基复合材料结构与性能之间的关系规律，并为电子封装或LED封装等潜在应用领域奠定坚实的理论和研究基础。在本项目资助下,已在J. Mater. Chem. A、Composite Part A、Mater. Des.和《绝缘材料》等国内外期刊发表学术论文36篇，其中SCI论文29篇，中文核心论文7篇；申请提交了一项发明专利；指导或联合指导了6名硕士生,参加国内外学术会议7次。