In this work, 3-aminopropyltriethoxysilane (AMEO)/polyurea (PUA)-modified silicon carbide whiskers (SiCw) were firstly fabricated and then incorporated into polyetherimide (PEI) to prepare the dielectric composites toward high temperature application. The results show that the introduction of amino/urea polar groups can effectively promote dielectric constant and suppress the dielectric loss of composites at room and high temperatures owing to the strong interfacial adhesion and deep trap effect of polar groups. Specifically, the variations of dielectric properties are also greatly dependent upon the surface functionalization of SiCw. SiCw-PUA endows the composites with relatively better comprehensive dielectric performances (dielectric constant of 18.3 and dielectric loss of 0.020) at room temperature while SiCw-AMEO has more apparent role in maintaining the dielectric performances (dielectric constant of 17.0 and dielectric loss of 0.029) at high temperature of 150 ℃. Furthermore, the composites also exhibit high thermal conductivity with the maximum thermal conductivities of 1.41 and 1.37 W m^-1 K^-1 for the SiCw-AMEO/PEI and SiCw-PUA/PEI at filler loading of 15 wt%, respectively. The excellent reinforcement effect of the surface functionalized SiCw also endows the composites with more application probability. This work on functionalization of SiCw could be applicable for integration of dielectric, thermally

conductive and mechanical properties.

在这项工作中，首先制备了 3-氨基丙基三乙氧基硅烷 (AMEO)/聚脲 (PUA) 改性的碳化硅晶须 (SiCw)，然后将其掺入聚醚酰亚胺 (PEI) 中以制备面向高温应用的介电复合材料。结果表明，氨基/脲极性基团的引入可以有效提高介电常数，抑制复合材料在室温和高温下的介电损耗，这是由于极性基团具有很强的界面附着力和深陷阱效应。具体而言，介电性能的变化也很大程度上取决于 SiCw 的表面功能化。SiCw-PUA赋予复合材料相对较好的综合介电性能（介电常数为18.3，介电损耗为0。020）在室温下，而 SiCw-AMEO 在 150 ℃高温下保持介电性能（介电常数为 17.0，介电损耗为 0.029）的作用更为明显。此外，复合材料还表现出高导热性，最大导热率为 1.41 和 1.37 W·m^-1 K ^-1对于 SiCw-AMEO/PEI 和 SiCw-PUA/PEI，填料含量分别为 15 wt%。表面功能化SiCw优异的增强效果也赋予了复合材料更多的应用可能性。这项关于 SiCw 功能化的工作可适用于电介质、热

导电和机械性能。