Key Takeaways & Executive Findings
- •• Achieved ultrahigh EMI shielding efficiency of 85.4 dB and specific SE of 791.2 dB cm3 g⁻1 in the X-band. • Demonstrated excellent flame retardancy with PHRR reduced by 65.8% and total heat release of only 0.58 kJ g⁻1. • Exhibited low thermal conductivity of 0.104 W m⁻1 K⁻1, providing effective thermal insulation. • Developed a core–shell structured CNF/PANI aerogel via seed polymerization, enhancing conductive network stability and PANI loading.
Abstract
The rapid development of communication technology and high-frequency electronic devices has created a need for more advanced electromagnetic interference (EMI) shielding materials. In response to this demand, a study has been conducted to develop multifunctional carbon nanofibers (CNFs)/polyaniline (PANI) aerogels with excellent electromagnetic interference shielding, flame retardancy, and thermal insulation performance. The process involved freeze-drying of electrospun CNFs and PANI nanoparticles followed by in situ growth PANI to coat the CNFs, creating the core–shell structured CNFs/PANI composite fiber and its hybrid aerogels (CP-3@PANI). The interaction between PANI and aniline (ANI) provides attachment sites, allowing additional ANI adsorption into the aerogel for in situ polymerization. This results in PANI uniformly covering the surface of the CNFs, creating a core–shell composite fiber with a flexible CNF core and PANI shell. This process enhances the utilization rate of the ANI monomer and increases the PANI content loaded onto the aerogel. Additionally, effective connections are established between the CNFs, forming a stable, conductive three-dimensional network structure. The prepared CP-3@PANI aerogels exhibit excellent EMI shielding efficiency (SE) of 85.4 dB and specific EMI SE (SE d−1) of 791.2 dB cm3 g⁻1 in the X-band. Due to the synergistic flame-retardant effect of CNFs, PANI, and the dopant (phytic acid), the CP-3@PANI aerogels demonstrate outstanding flame-retardant and thermal insulation properties, with a peak heat release rate (PHRR) as low as 7.8 W g⁻1 and a total heat release of only 0.58 kJ g⁻1. This study provides an effective strategy for preparing multifunctional integrated EMI shielding materials.
1. Introduction
The rapid development and widespread adoption of 5G technology and millimeter wave technology have significantly improved communication speed and efficiency. However, these advancements also come with challenges, particularly regarding electromagnetic interference (EMI) and electromagnetic radiation pollution. This affects the operation of precision devices and poses significant health risks. Consequently, EMI shielding materials have garnered considerable attention to address this critical issue effectively.
Researchers have primarily concentrated on improving the efficiency of shielding and reducing the weight and thickness of EMI shielding materials for potential use in civilian and military equipment. Various nanostructured materials, such as carbon nanotubes (CNTs), graphene, transition metal carbides, metal nanowires, and conductive polymers, have been widely used in the field of EMI shielding. Despite these advancements, most previous research has mainly focused on enhancing EMI shielding performance. However, future applications of EMI shielding materials may extend to more complex real-world scenarios, necessitating multifunctional materials to meet application requirements.
Absorbing electromagnetic waves (EMW) often generates heat, which can cause structural degradation and pose safety hazards. Consequently, EMI shielding materials that are flame-retardant and thermally insulating are essential, as they can effectively mitigate indoor EMI and pollution while preventing hazards to buildings from the heat generated by EMW absorption. Moreover, flexible and flame-retardant EMI shielding materials are highly sought after for wearable electronic devices, where high flame resistance can prevent thermal runaway and fire risks from prolonged use.
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Mingyi Chen, Jian Zhu, Kai Zhang, Hongkang Zhou, Yufei Gao, Jie Fan, Rouxi Chen, Hsing-Lin Wang (2024). Carbon Nanofiber/Polyaniline Composite Aerogel with Excellent Electromagnetic Interference Shielding, Low Thermal Conductivity, and Extremely Low Heat Release. Nano-Micro Letters. https://doi.org/10.1007/s40820-024-01583-2
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Frequently Asked Questions
What is the EMI shielding efficiency of the CNF/PANI aerogel?
The CNF/PANI aerogel exhibits an EMI shielding efficiency of 85.4 dB in the X-band, with a specific shielding effectiveness of 791.2 dB cm3 g⁻1.
How does the aerogel achieve flame retardancy?
The flame retardancy is achieved through the synergistic effect of carbon nanofibers, polyaniline, and phytic acid dopant, resulting in a peak heat release rate as low as 7.8 W g⁻1 and total heat release of only 0.58 kJ g⁻1.
What is the thermal conductivity of the aerogel?
The aerogel has a low thermal conductivity of 0.104 W m⁻1 K⁻1, providing excellent thermal insulation.
What is the structural design of the aerogel?
The aerogel features a core-shell structure where carbon nanofibers form the core and polyaniline forms the shell, created via seed polymerization and in situ growth, resulting in a stable conductive network.
What are the potential applications of this material?
The material is suitable for advanced EMI shielding in electronics, aerospace, and wearable devices, where combined shielding, flame retardancy, and thermal insulation are required.
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