Enhanced Thermal Conductivity and EMI Shielding of Polyimide Composites Based on a Three-Dimensional Interconnected Graphene@Graphite Network

Abstract

Nowadays, lightweight dual-functional polymer composites with great heat conductance and high electromagnetic interference (EMI) shielding performance are urgently needed in modern developing technology. Furthermore, efficient multipaths within network designed with multifunctional fillers in composites prefer to be a better way to balance the heat flow or electromagnetic signal transmission generated in dense integrated electronic devices. In this study, a strategy of graphite-graphene combined network-loaded polyimide (PI) composites was enabled by a scalable and tractable polymer-infiltrated technique. In this network, the microscale reduced graphene oxide (rGO) serves as an adhesive interfacial bridge and thermal network architect, effectively maintaining the macroscale worm-like structure of expanded graphite (EG). The framework was built using a template-free method from hydrogel to aerogel at low temperatures by immersing polyamic acid salt in the ensemble, followed by freeze-drying and final hot-pressing to obtain polyimide composites (rGO@EG/PI). In composites, the microregion network built by macro-micro structured hybrid fillers provides the polymer with multiscale connection channels, leading to an enhancement of the final properties of the samples. The prepared composite exhibits a great thermal conductivity (λ// = 9.4 W·m–1 K–1) with a 47 wt % hybrid filler loading, achieving 1781% higher than the polymer, accompanied by an exceptional level of EMI SE (61 dB). Moreover, the PI composites are found to possess excellent thermal properties, thermal management, and electrical conductivity. With great comprehensive performance, the rGO@EG/PI composites are of good promise for thermal management applications and EMI shielding performance in the field of high integrated technology.