Thermal shock exfoliated and siloxane cross-linked graphene framework for high performance epoxy-based thermally conductive composites

Abstract: The fabrication of epoxy/graphene composites with greatly enhanced thermal conductivity (K) in terms of efficient thermal dissipation of electronic devices has drawn much interest. However, the lack of continuous thermal conductive paths and thermal interface resistances generated between matrix and fillers limit the further enhancement of the K value. Here, a siloxane cross-linked graphene framework (SGF) with highly conductive paths is prepared by a simple way, i.e., thermal-shock exfoliation of graphene oxide film followed by self-polymerization of silanol inside GF. The epoxy (EP) resin was then impregnated into SGF to form the EP/SCF composite. The mutual percolation of EP and SGF in the composite eliminates the distribution issue of graphene sheets. The siloxane molecular network not only cross-links adjacent graphene sheets, but also forms chemical bonding with EP matrix, resulting in significantly decreased inter-sheet and interface thermal resistances. The EP/SGF composite containing 20.2 wt% graphene exhibits an in-plane K of 54.2 W m^–1 K^–1, which is about twice higher than that of EP/GF without siloxane and 270 times higher than pure EP. Graphical Abstract: [Figure not available: see fulltext.]