Enhanced Thermal Conductivity in Poly(ether imide)-Based Composites via Constructing Microscopic Segregated Networks with Ag-Bridged Graphite Nanoplatelets

In recent years, polymer-based composites with high thermal conductivity have become important for the effective removal of accumulated heat in thermal management devices, though enhancing the thermal conductivity of poly(ether imide) materials remains challenging. Herein, to prepare high-thermal-conductivity materials, silver nanoparticles are chemically reduced onto the surface of graphite nanoplates as hybrid fillers. Consequently, inspired by "cellular structures", segregated thermally conductive networks in composites are designed by mixing hybrid fillers and poly(ether imide) microspheres, followed by a hot-pressing process. Benefiting from the three-dimensional heat-transfer network and the bridging effect of silver nanoparticles, thermal conduction pathways are easily constructed, reducing interfacial heat resistance in the polymer matrix. At a hybrid filler loading of 40 wt %, the through-plane and in-plane thermal conductivities reach 4.7 and 11.3 W/m K, respectively. Moreover, the finite-element simulation reveals that the composites have high thermally conductive ability owing to the hybrid fillers, which offer highly effective pathways for phonon transmission. Besides, polymer composites exhibit a great electrical magnetic shielding performance (30.5 dB). In summary, this study provides a strategy for fabricating thermally conductive polymer-based composite materials for use in industrial heat dissipation devices.