Abstract
Reduced graphene oxide (RGO) and three-dimensional graphene networks (3DGNs) are adopted to improve the performance of thermal interface materials (TIMs). Therein, the 3DGNs provide a fast transport network for phonons, while the RGO plays as a bridge to enhance the phonon transport ability at the interface between the filler and matrix. The types of surface functional groups of the RGO are found to exert a remarkable influence on the resulting thermal performance; the carboxyl groups are found in the optimal selection to promote the transport process at the interface area because a strong chemical bond will form between the graphene basal plane and epoxy resin (ER) through this kind of group. The resulting thermal conductivity reaches 6.7 Wm−1 K−1 after optimizing the mass fraction and morphology of the filler, which is 3250% higher than that of the pristine ER. Moreover, the mechanical properties of these as-prepared TIMs are also detected, and the specimens by using the RGO(OOH) filler display the better performances.
Highlights
Thermal interface materials (TIMs) became one of hot issues during the last decade because of the increasing demands on dissipating heat of the highly integrated electron devices [1,2,3,4]
As for the reduced graphene oxide (RGO) sample, the presence of wrinkles is spontaneous to enhance its stability, while the discrepancy between the thermal expansion coefficients of the graphene and nickel substrate leads to the wrinkles of the Three-dimensional graphene networks (3DGNs)
Partial RGO fillers can be seen on the surface of the RGO-epoxy resin (ER) specimens (Fig. 1d–f ), while some obvious concave-convex appear on the surface of the 3DGNs-ER (Fig. 1g)
Summary
Thermal interface materials (TIMs) became one of hot issues during the last decade because of the increasing demands on dissipating heat of the highly integrated electron devices [1,2,3,4]. Compared with that of the traditional fillers (such as SiC, Al2O3, and BN), graphene displays a promising prospect to modify the epoxy resin (ER) based on its outstanding high thermal conductivity (5000 Wm−1 K−1 for the monolayer sample) [5]. The mass fraction of traditional fillers should excess 50% to satisfy the actual demand, leading to a poor mechanical performance of the resulting composites. A low ratio of the reduced graphene oxide (RGO) filler (~ 20 wt%) brings about a high thermal conductivity (~ 4 Wm−1 K−1) for the composite TIMs. Based on Balandin’s and Lu’s reports, the the high defect density and poor continuity of the RGO (due to the violent oxidation-reduction reactions) limit the further enhancement of the resulting thermal performances [10]. The three-dimensional graphene networks (3DGNs) prepared by chemical vapor deposition method possess a high quality, the lack of an efficient link to achieve a favorable contact between the graphene basal plane and ER obstructs the phonon
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