Abstract
Natural graphite flakes possess high theoretical thermal conductivity and can notably enhance the thermal conductive property of polymeric composites. Currently, because of weak interaction between graphite flakes, it is hard to construct a three-dimensional graphite network to achieve efficient heat transfer channels. In this study, vertically aligned and interconnected graphite skeletons were prepared with graphene oxide serving as bridge and support via freeze-casting method. Three freezing temperatures were utilized, and the resulting graphite and graphene oxide network was filled in a polymeric matrix. Benefiting from the ultralow freezing temperature of −196 °C, the network and its composite occupied a more uniform and denser structure, which lead to enhanced thermal conductivity (2.15 W m−1 K−1) with high enhancement efficiency and prominent mechanical properties. It can be significantly attributed to the well oriented graphite and graphene oxide bridges between graphite flakes. This simple and effective strategy may bring opportunities to develop high-performance thermal interface materials with great potential.
Highlights
With the rapid development of electronic devices, thermal dissipation has become a critical necessity for its reliability, lifetime, and high speed [1,2,3]
The inorganic thermal conductive fillers are uniformly dispersed in polymer matrix to obtain the high thermal conductivity, including metals [10,11,12], α-alumina (α-Al2 O3 ) [13,14,15], hexagonal boron nitride (h-BN) [16,17,18,19], nanoclays [20], carbon nanotubes (CNTs) [21,22,23,24], and their hybrid mixtures [25,26]
It can be seen that several types of functional groups were attached to the surface of Graphene oxide (GO) without existing on graphite flakes
Summary
With the rapid development of electronic devices, thermal dissipation has become a critical necessity for its reliability, lifetime, and high speed [1,2,3]. The vacuum filtration method was skillfully developed and utilized to achieve the oriented structures of thermal conductive fillers [26,42]. This method always shows notable availability for fabricating the paper-like composites [43] and obtaining high value of thermal conductivity in the horizontal direction. It has been clearly demonstrated that GO can interconnect with each other and assemble into a stable and specific structure by the ice-templating self-assembly method [1,54,62,63,64] It presents significant potential for serving as the bridge and support of graphite flakes and forming 3D graphite networks. The thermal conductivity and mechanical properties were reasonably evaluated and analyzed, especially the impacts of the extremely low freezing temperature
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