Vertical Graphene Nanosheet/Polyimide Composite Films for Electromagnetic Interference Shielding

Abstract

The development of carbon nanocomposite with high-performance electromagnetic interference (EMI) shielding has become vitally important for next-generation intelligent electronic devices. However, efficient EMI shielding for highly flexible and miniaturized devices is still a challenge. Here, a highly flexible and thin composite film composed of vertical graphene nanosheets (VGSs) and polyimide (PI) for EMI shielding is proposed. VGSs are prepared by activation-induced thermal chemical vapor deposition (CVD) for the first time, and the composite film is prepared by composing VGSs with PI via in situ polymerization. With the isotropic urchin-like nanostructure and agglomeration-free dispersion of VGSs, rich electrons conduction paths, enclosure nanostructure, and countless interfaces are constructed in PI matrix. The optimal composite film shows superior EMI shielding performance (an average EMI shielding effectiveness of 31.37 dB in the frequency range of 8.2–12.4 GHz can be detected with a thickness of 151 μm). Furthermore, the composite film also shows excellent thermal management performance. Suitable flexibility and robustness allow the composite film to bear even 2000 continuous bending cycles, and without appreciably decreasing its EMI shielding and thermal management performance, which establishes potentials for applications in EMI shielding and thermal management.

Synthesis of Vertical Graphene Nanowalls on Substrates by PECVD as Effective EMI Shielding Materials

“…A value of SE/ t ( t represents the thickness of materials) is used to fully estimate the performance and compared it with other reported films applied as EMI shielding materials (Figure b and Table ). − The SE/ t of VGNs and VGNs/Cu foam composite films maintain high values over 500 dB·mm –1 , outperforming most of the values in reported works.…”

Flexible, Stretchable, and Thin Films Based on Functionalized Carbon Nanofiber/Graphene Nanostructures for Electromagnetic Interference Shielding

“…The peaks of CNF, FCNF, EG, and GNP at 1565, 1567, 1582, and 1586 cm −1 , respectively, are connected to the G band and serve to confirm the presence of sp 2 graphitic carbon. The D and G band intensity ratio, i.e., I D /I G , was used to gauge the severity of the defect that contributes to improving 37 the conductivity.…”

High Out-of-Plane Thermally Conductive Polyimide Film for Electronic Thermal Management by the Incorporation of Core–Shell Ag/Polyimide Microparticles

“…To deeply understand the thermal conductivity improvement efficiency, the enhancement in thermal conductivity per unit filler loading as a function of filler loading is presented in Figure h. Certainly, compared to other thermally conductive fillers such as BNNS and graphene, ,,,− Ag-based fillers exhibit significant advantages in improving the thermal conductivity of polymers in the out-of-plane direction. Interestingly, PI/PIM@Ag-30 in our work exhibits the highest thermal conductivity improvement efficiency and the lowest filler content compared with most AgNP-based composites.…”

“…Considering that heat is transferred in all directions, a substantial enhancement of the out-of-plane thermal conductivity of PI films is desired. Currently, many strategies have been employed to upgrade the out-of-plane thermal conductivity of PI films, such as chemical vapor deposition, templates, external field induction, and the preparation of isotropic thermally conductive fillers. ,− Among these strategies, because of the simple and large-scale feature, isotropic thermally conductive fillers exhibit a huge potential in industrial applications. Duan et al reported a PI composite film with BN nanosheet-coated Al 2 O 3 microspheres (Al 2 O 3 @BN) as isotropic thermally conductive fillers.…”