Tuning the Oxidation Degree of Graphite toward Highly Thermally Conductive Graphite/Epoxy Composites

Efficient removal of heat is one of the most challenging issues in the development of modern electronic devices. However, traditional thermal interface materials (TIMs) may exhibit limited thermal conductivity when loaded with thermally conductive fillers at high contents due to irrational filler/polymer structures. In this work, graphite oxide (GrO) with different oxidation degrees was prepared by a controlled Hummers method and used as fillers for the enhancement of thermal conductivity of epoxy. Our experiment revealed that the thermal conductivity of the obtained composites greatly depends on the oxidation degree of GrO. Furthermore, GrO with a mild oxidation degree exhibits edge-functionalization characteristics and possesses a strong ability to enhance the thermal conductivity of epoxy because edge-functionalized GrO is able to provide a preferential conducting pathway for heat transfer in the epoxy matrix. This work provides new insight into the preparation of high-performance TIMs for microelectronic packaging.