Effective lightweight, flexible and ultrathin PVDF/rGO/Ba₂Co₂Fe₁₂O₂₂ composite films for electromagnetic interference shielding applications

Abstract

In this study, we developed a simple and cost-effective solvent film casting method to fabricate ultrathin, flexible and lightweight polyvinylidenefluoride (PVDF)-based composites that provide high electromagnetic interference (EMI) shielding performance. Y-type barium hexaferrite with general formula Ba 2 Co 2 Fe 12 O 22 was first synthesized by the sol-gel autocombustion method and then reduced graphene oxide (rGO) was prepared by modified Hummer's method. The crystal structure, morphology, elemental surface analysis and magnetic properties of the samples were systematically investigated using x-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, energydispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and vibrating sample magnetometry. Then, the complex permittivity, complex permeability and EMI shielding properties of the flexible PVDF/rGO/Ba 2 Co 2 Fe 12 O 22 composite films with two different amounts of Ba 2 Co 2 Fe 12 O 22 NP content and a fixed amount of rGO content were investigated using a vector network analyzer. The structural characterizations of the resultant composite films showed the formation of an electroactive β-phase of PVDF with addition of Ba 2 Co 2 Fe 12 O 22 nanoparticles and rGO content. The enhancement of the β-phase in the PVDF/rGO/Ba 2 Co 2 Fe 12 O 22 nanocomposites was explained from a physicochemical viewpoint. Furthermore, the electrically conductive and magnetic properties of PVDF composite films incorporating rGO and Ba 2 Co 2 Fe 12 O 22 NPs exhibited a high EMI shielding effectiveness of 25.63 dB, with an absorptiondominated shielding feature in the 8-12 GHz region. The enhanced absorption was attributed to the electrostatic interaction induced by the β-phase fraction in the PVDF matrix, and subsequently from multiple reflections and magnetic loss originating from the synergetic effect of rGO and Ba 2 Co 2 Fe 12 O 22 NPs. This study introduces a low-cost and scalable method for the design of novel, lightweight, flexible and efficient EMI shielding composite films with promising prospects for application in the construction, electronics and aerospace fields.

New construction strategies of carbon‐based composites for flexible electromagnetic interference shielding films

“…They also improve the impedance matching, and strengthen the energy moves between contiguous state to Fermi level. 2,32,76,77 However, the traditional reduction method cannot fully remove the substituent groups and defects of GO, which reduces conductivity of graphene. Some studies show that ultrahightemperature (>2000 C) annealing can recover the defects and generate excellent conductivity.…”

“…Moreover, EMI shielding is a comprehensive outcome of dielectric and magnetic loss, one of the decisive factors is how well they match. 57,77,[91][92][93][94][95] Figure 1 is a schematic overview of the construction strategy of high performance flexible carbonaceous EMI shielding films and their multi-functionality. First, the construction of layered structure like "brick-mortar," porous structure, cell-like structure, or segregated structure are novel strategies to improve the multiple reflections and dielectric loss.…”

“…The functional groups and defects suspended on GO will lead to polarization and strong dielectric loss to increase EMI shielding effectiveness. They also improve the impedance matching, and strengthen the energy moves between contiguous state to Fermi level 2,32,76,77 . However, the traditional reduction method cannot fully remove the substituent groups and defects of GO, which reduces conductivity of graphene.…”

Reduced Graphene Oxide/Barium Ferrite Ceramic Nanocomposite Synergism for High EMI Wave Absorption

“…On the other hand, conductive carbon-based shielding materials, such as reduced graphene oxide (RGO) and carbon nanotubes (CNTs), have low density and high dielectric loss, making them good electromagnetic wave absorbers. − Since it was difficult to offer a shielding material with good magnetic and dielectric losses, composites attracted researchers’ interest in surpassing the limitations of the individual material and offering a wide variety of combinations to promote composite-shielding capabilities by fine tuning its magnetic and dielectric losses. − RGO has shown potential as a shielding agent among all carbonaceous materials due to its excellent conductivity and high surface area. In addition, its preparation using the top-down chemical synthesis approach had the advantage of being easily processed with a high yield, making it a promising candidate in many composites. − The enhancement reached through the formation of ceramic composites depends on the synergistic effect of dielectric and magnetic losses, which promote interfacial polarization and charge transfer, leading to an effective EMI ceramic sheet absorber. , This phenomenon provides composites with different permittivity and permeability values, which rely on the ratio between conductive and magnetic particles altering their impedance and raising their absorption shielding performance besides the consistent arrangement of minute nanoparticles. − The known ceramic formation techniques are slip casting, additive manufacturing, and technical ceramics. , The technical ceramic technique is widely used for dry powder processing into the required shape via mechanical or hydraulic powder compacting presses selected for the necessary force and powder fill depth. The creation of the basic shape of a component is achieved by compacting powder material through the application of external pressure using either single-action or double-action compaction techniques .…”

“… 31 − 33 The enhancement reached through the formation of ceramic composites depends on the synergistic effect of dielectric and magnetic losses, which promote interfacial polarization and charge transfer, leading to an effective EMI ceramic sheet absorber. 34 , 35 This phenomenon provides composites with different permittivity and permeability values, which rely on the ratio between conductive and magnetic particles altering their impedance and raising their absorption shielding performance besides the consistent arrangement of minute nanoparticles. 36 − 38 The known ceramic formation techniques are slip casting, 39 additive manufacturing, 40 and technical ceramics.…”