Role of oxygen functional groups for improved performance of graphene-silicone composites as a thermal interface material

Abstract We report the findings of our experimental investigation on the performance of reduced graphene oxide (rGO)/silicone composite as a thermal interface material (TIM) influenced by the loading factor, surface functionality, and structural properties of graphene. The experimental data reveals that in addition to the loading factor, the thermal conductance of TIMs is greatly impacted by the density of oxygen-functionality (phenolic group) in rGO, and the morphological and structural properties introduced during the thermal reduction (deoxygenation) of graphene oxide to rGO. In particular, the phenolic groups prominently formed on the basal plane of rGO play a significant role in decreasing the interfacial thermal resistance. The results also show that the larger sp2 graphitic structures and the morphological properties of rGO increase the degree of dispersion in the matrix. A dynamic interplay between these factors determines the final value of the thermal conductance observed for different composites. An optimum combination of these factors led to the maximum thermal conductance (541 W/m 2 K) for the T-rGO600 (thermally-reduced graphene oxide processed at 600 °C)/silicone composite. The proposed underlying physics backed by the experimental data should be useful in designing high thermal performance TIMs with carbonaceous nanomaterials, including carbon nanotubes, graphene nanoplatelets, and carbon blacks acting as additives.