Three-dimensional interconnected networks for thermally conductive polymer composites: Design, preparation, properties, and mechanisms

With the development of science and technology, microelectronic components have evolved to become increasingly integrated and miniaturized. As a result, thermal management, which can seriously impact the function, reliability, and lifetime of such components, has become a critical issue. Recently, the use of polymerbased thermal interface materials (TIMs) in thermal management systems has attracted considerable attention in view of the superior comprehensive properties of the former. Compared with designing and fabricating a polymer with an intrinsically high thermal conductivity, a more effective and widely used strategy for improving the heat conductivity is to fill a polymer matrix with a thermally conductive filler. Specifically, three-dimensional (3D) interconnected heat-conductive networks can increase the thermal conductivity (k) of polymers more effectively than dispersed fillers can, owing to their intrinsic continuous structures. In this review, we first introduce the heat conduction mechanisms and the problems associated with polymer-based TIMs fabricated using engineering polymer chains and traditional filling methods. Next, we discuss the advantages and mechanisms of 3D interconnected heat-conductive networks for preparing thermally conductive polymer-based composites. In addition, we highlight new advancements in the design and fabrication of 3D thermally conductive networks as well as their application in improving the k of polymers. Our exhaustive review of 3D interconnected networks includes graphene, carbon nanotubes, boron nitride, metal and other 3D hybrid architectures. The key structural parameters and control methods for improving the thermal properties of polymer composites are outlined. Finally, we summarize some effective strategies and possible challenges for the development of polymer-based thermally conductive composites via integration with 3D interconnected networks.