Optimizing impedance matching and interfacial characteristics of aromatic polyimide/graphene by molecular layer deposition for heat-conducting microwave absorption

Heat-conduction microwave absorbers with outstanding electromagnetic wave (EMW)-absorption and thermal-management performances are considerably attractive in the field of modern electronic devices. Herein, by uniformly depositing aromatic polyimide (PI) on the surface of graphene through a molecular layer deposition (MLD) method and tuning the number of deposition cycles, PI/graphene (PI/G) composites with excellent microwave-absorption and thermal-management properties were successfully fabricated. The as-prepared sample displayed a high-efficiency reflection loss (RL) of -57.16 dB and a wide effective absorbing bandwidth (EAB) of 4.32 GHz with a filling content of merely 5 wt%. Benefiting from the outstanding dielectric loss, appropriate impedance matching, and strong attenuation capacity, PI/G demonstrated strong, wide band, and excellent low-frequency absorption. In light of the radar cross-sectional (RCS) simulation results, PI/G could significantly suppress the strong scattering of EMWs. In addition, PI/G/natural rubber (PI/G/NR) composites exhibited remarkable thermal conductivity, flexibility, and smooth surface. This work paves the way for the preparation of highly efficient heat-conduction microwave absorbers with the direction of RCS simulations and offers an interesting option in the electronic packaging field.

Automated summary

By depositing aromatic polyimide (PI) on the surface of graphene through a molecular layer deposition (MLD) method and tuning the number of deposition cycles, PI/graphene (PI/G) composites with excellent microwave-absorption and thermal-management properties were successfully fabricated. The as-prepared sample displayed a high-efficiency reflection loss (RL) and a wide effective absorbing bandwidth (EAB), showing strong, wide band, and excellent low-frequency absorption. This work offers a new approach for the preparation of highly efficient heat-conduction microwave absorbers and provides an interesting option in the electronic packaging field.