Polymer composites with super-high thermal conductivity have attracted many interests in aerospace and electrical fields. However, traditional polymer composites usually suffer from low thermal conductivity because of the high interfacial thermal resistance. Herein, by adopting a multi-dimensional filler composed of micro-silver (AgMP) and nano-silver (AgNP) particles, we prepare an epoxy/Ag composite with the maximum thermal conductivity of 58.3 W/m·K. Based on this, by introducing trace amount (0.12 vol%) of MXene, the thermal conductivity of the epoxy/Ag/MXene composite further increases to 72.7 W/m·K, which is 24.7% higher than that of Ag/Epoxy composites. Both of the super-high thermal conductivity enhancement in epoxy/Ag and epoxy/Ag/MXene composites should be attributed to the unique bridging effect of AgNP particles or MXene flakes. AgNP bridges AgMP via sintering while the MXene flakes bridge AgNP and/or AgMP by the strong interaction between MXene flakes and the Ag particles. The significant effect of the bridging between filler particles on the thermal conductivity of composites is elucidated and verified by FEM simulations. These findings provide new insights into the thermal transport in polymer-based composites and also suggest an approach to prepare polymer composites with super-high thermal conductivity.

具有超高热导率的聚合物复合材料在航空航天和电气领域引起了许多兴趣。然而，传统的聚合物复合材料由于界面热阻高，通常导热系数低。在此，我们采用由微银 (AgMP) 和纳米银 (AgNP) 颗粒组成的多维填料，制备了最大导热系数为 58.3 W/m·K 的环氧树脂/Ag 复合材料。在此基础上，通过引入微量（0.12 vol%）的MXene，环氧树脂/Ag/MXene复合材料的导热系数进一步提高到72.7 W/m·K，比Ag/Epoxy复合材料的导热系数高24.7%。环氧树脂/银和环氧树脂/银/MXene复合材料的超高导热性增强应归因于AgNP颗粒或MXene薄片的独特桥接效应。AgNP 通过烧结桥接 AgMP，而 MXene 薄片通过 MXene 薄片和 Ag 颗粒之间的强相互作用桥接 AgNP 和/或 AgMP。通过有限元模拟阐明和验证了填料颗粒之间的桥接对复合材料热导率的显着影响。这些发现为聚合物基复合材料的热传输提供了新的见解，也提出了一种制备具有超高导热性的聚合物复合材料的方法。