Abstract Polyimide (PI) has excellent resistance to high or low temperatures due to its unique molecular structure, and is widely used in advanced electronics and power systems in extreme ...environments. In recent years, a small amount of studies have been published to modulate the dynamic behavior of PI such as self‐healable, recyclable, and degradable abilities by adjusting the structure of molecular chains and the composition of monomers. However, the conceptual design, formation conditions, and application prospects of dynamic PI are still unclear. In this paper, the new concepts and systems of dynamic PI are introduced from the perspective of the design of molecular structure, the development of regulating performance area, and the application of extreme insulation, based on recent work and other representative work. Specifically, this work appeals to researchers involved in PI synthesis, smart, dielectric, energy storage, and extreme insulation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
With the development of flexible electronic devices and large‐scale energy storage technologies, functional polymer‐matrix nanocomposites with high permittivity (high‐k) are attracting more attention ...due to their ease of processing, flexibility, and low cost. The percolation effect is often used to explain the high‐k characteristic of polymer composites when the conducting functional fillers are dispersed into polymers, which gives the polymer composite excellent flexibility due to the very low loading of fillers. Carbon nanotubes (CNTs) and graphene nanosheets (GNs), as one‐dimensional (1D) and two‐dimensional (2D) carbon nanomaterials respectively, have great potential for realizing flexible high‐k dielectric nanocomposites. They are becoming more attractive for many fields, owing to their unique and excellent advantages. The progress in dielectric fields by using 1D/2D carbon nanomaterials as functional fillers in polymer composites is introduced, and the methods and mechanisms for improving dielectric properties, breakdown strength and energy storage density of their dielectric nanocomposites are examined. Achieving a uniform dispersion state of carbon nanomaterials and preventing the development of conductive networks in their polymer composites are the two main issues that still need to be solved in dielectric fields for power energy storage. Recent findings, current problems, and future perspectives are summarized.
1D/2D carbon nanomaterial‐polymer dielectric composites are a promising way to realize excellent dielectric properties and high energy density with low filler concentration, which are essential in power energy storage application. Progress in recent years is summarized and the advantages and disadvantages of different strategies are identified to provide clearer paths for researchers in this field.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Dielectric capacitors with a high operating temperature applied in electric vehicles, aerospace and underground exploration require dielectric materials with high temperature resistance and high ...energy density. Polyimide (PI) turns out to be a potential dielectric material for capacitor applications at high temperatures. In this review, the key parameters related to high temperature resistance and energy storage characteristics were introduced and recent developments in all-organic PI dielectrics and PI-matrix dielectric nanocomposites were discussed. Synthetic strategies for new functional PI
via
modification at the molecular level together with the design engineering of nanofillers and multilayer structures of PIs were also analysed. Finally, a systematic summary of the current challenges and future developments for capacitor materials used at high temperatures were presented.
Dielectric capacitors with a high operating temperature applied in electric vehicles, aerospace and underground exploration require dielectric materials with high temperature resistance and high energy density.
Dielectric polyimides (PIs) are ubiquitous as insulation in electrical power systems and electronic devices. Generally, dynamic polyimide is required to solve irreversible failure processes of ...electrical or mechanical damage, for example, under high temperature, pressure, and field strength. The challenge lies in the design of the molecular structure of rigid polyimide to achieve dynamic reversibility. Herein, a low‐molecular‐weight polyimide gene unit is designed to crosslink with polyimide ligase to prepare the smart film. Interestingly, due to the variability of gene unit and ligase combinations, the polyimide films combining hardness with softness are designed into three forms via a “Mimosa‐like” bionic strategy to adapt to different application scenarios. Meanwhile, the films have good degradation efficiency, excellent recyclability, and can be self‐healable, which makes them reuse. Clearly, the films can be used in the preparation of ultrafast sensors with a response time ≈0.15 s and the application of corona‐resistant films with 100% recovery. Furthermore, the construction of polyimide and carbon‐fiber‐reinforced composites (CFRCs) has been verified to apply to the worse environment. Nicely, the composites have the property of multiple cycles and the non‐destructive recycle rate of carbon fiber (CF) is as high as 100%. The design idea of preparing high‐strength dynamic polyimide by crosslinking simple polyimide gene unit with ligase could provide a good foundation and a clear case for the sustainable development of electrical and electronic polyimides, from the perspective of Mimosa bionics.
A dynamic polyimide (PI) film, which can transform among three molecular structures, is designed by imitating the behavior of the Mimosa plant. The PI film is a super‐corona‐resistant film, a matrix of high‐sensitivity humidity sensor and carbon‐fiber‐reinforced composites due to its excellent capabilities of degradation, self‐healable ability, and recyclability.
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Polyimides (PIs) are widely used in circuit components, electrical insulators, and power systems in modern electronic devices and large electrical appliances. Electrical/mechanical damage of ...materials are important factors that threaten reliability and service lifetime. Dynamic (self-healable, recyclable and degradable) PIs, a promising class of materials that successfully improve electrical/mechanical properties after damage, are anticipated to solve this issue. The viewpoints and perspectives on the status and future trends of dynamic PI based on a few existing documents are shared. The main damage forms of PI dielectric materials in the application process are first introduced, and initial strategies and schemes to solve these problems are proposed. Fundamentally, the bottleneck issues faced by the development of dynamic PIs are indicated, and the relationship between various damage forms and the universality of the method is evaluated. The potential mechanism of the dynamic PI to deal with electrical damage is highlighted and several feasible prospective schemes to address electrical damage are discussed. This study is concluded by presenting a short outlook and future improvements to systems, challenges, and solutions of dynamic PI in electrical insulation. The summary of theory and practice should encourage policy development favoring energy conservation and environmental protection and promoting sustainability.
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To match the increasing miniaturization and integration of electronic devices, higher requirements are put on the dielectric and thermal properties of the dielectrics to overcome the problems of ...delayed signal transmission and heat accumulation. Here, a 3D porous thermal conductivity network is successfully constructed inside the polyimide (PI) matrix by the combination of ionic liquids (IL) and calcium fluoride (CaF2) nanofillers, motivated by the bubble‐hole forming orientation force. Benefiting from the 3D thermal network formed by IL as a porogenic template and “crystal‐like phase” structures induced by CaF2‐ polyamide acid charge transfer, IL‐10 vol% CaF2/PI porous film exhibits a low permittivity of 2.14 and a thermal conductivity of 7.22 W m−1 K−1. This design strategy breaks the bottleneck that low permittivity and high thermal conductivity in microelectronic systems are difficult to be jointly controlled, and provides a feasible solution for the development of intelligent microelectronics.
Through the dual action of calcium fluoride and ionic liquid on the polyimide (PI) matrix, the 3D porous thermal conductivity network and special “crystal‐like phase” structures are constructed in PI. These endow the PI materials with highly efficient low dielectric and thermal conductivity properties to better serve the electrical and electronic fields.
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The addition‐type liquid silicone rubber (ALSR) co‐filled with spheroidal Al2O3 and flaky BN was prepared by the mechanical blending and hot press methods to enhance the thermal, electrical, and ...mechanical properties for industrial applications. Morphologies of ALSR composites were observed by scanning electron microscopy (SEM). It was found that the interaction and dispersion state of fillers in the ALSR matrix were improved by the introduction of BN sheets. Thermal, electrical, and mechanical performances of the ALSR composites were also investigated in this work. The result indicated that the thermal conductivity of ALSR can reach 0.64 W m−1 K−1 at the loading of 20 wt% Al2O3/20 wt% BN, which is 3.76 times higher than that of pure ALSR. The addition of Al2O3 particles and BN sheets also improve the thermal stability of ALSR composites. Moreover, pure ALSR and ALSR composites showed relatively lower dielectric permittivity (1.9–3.1) and dielectric loss factor (<0.001) at the frequency of 103 Hz. The insulation properties including volume resistivity and breakdown strength were improved by the introduction of flaky BN in the ALSR matrix. The volume resistivity and characteristic breakdown strength E0 are 6.68 × 1015 Ω m and 93 kV/mm, respectively, at the loading of 20 wt% Al2O3/20 wt% BN. In addition, the mechanical characteristics including elongation at break and tensile strength of ALSR composites were also enhanced by co‐filled fillers. The combination of these improved performances makes the co‐filled ALSR composites attractive in the field of electrical and electronic applications.
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The advancement of the microelectronics industry necessitates the use of interlayer insulation materials with low dielectric constants and high mechanical properties. In this paper, a new type of ...copolymerized fluorinated polyimide (PI) is synthesized, and mixed with polyhedral oligomeric silsesquioxane (POSS) functionalized mesoporous silica (MCM‐41@POSS). The PI/MCM‐41@POSS composites exhibit good hydrophobicity. With the addition of 3 wt% MCM‐41@POSS, the PI composite attained an ultralow dielectric constant (k = 1.88) and low dielectric loss (0.01) at 1 MHz, which is attributed to the mesoporous structure of MCM‐41 and the restriction of polarization in the bonded region. The decorated POSS effectively prevents the penetration of PI molecular chains into the mesopores of MCM‐41. In addition, the PI composites containing 3 wt% of MCM‐41@POSS obtain the highest maximum stress of 104.03 MPa with an elongation at break of 13.73%. The hydrophobic PI composites with ultralow‐k are expected to be good candidates as interlayer materials in microelectronics devices.
A new type of copolymerized fluorinated polyimide (PI) with ultralow dielectric constant (1.88@1MHZ) and excellent hydrophobicity and mechanical properties is synthesized by introducing POSS functionalized mesoporous silica (MCM‐41@POSS). The hydrophobic ultralow dielectric constant polyimide composites are expected to be good candidates as interlayer materials in microelectronics devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Self-healing of damage is a common phenomenon in organisms but is hardly ever encountered in rigid polymer materials. For next-generation electricals and electronics, it is crucial to accurately ...mimic organisms to detect and heal mechanical/electrical damage. Herein, disulfide bond exchange is designed to introduce the self-healing ability in a copolymerized polyimide (copolyimide). A copolyimide insulation film with two diamine monomers is successfully prepared, which also possesses good self-healing ability after being mechanical/electrical damaged. Furthermore, the self-healing copolyimide film still maintains its good Young's modulus (
E
) >4 GPa, high thermal stability with glass transition temperature (
T
g
) >190 °C, and excellent insulation property with breakdown strength (
E
b
) >300 kV mm
−1
. The combination of the simple copolymerization and unique self-healing ability is suitable for high
T
g
polyimide to make this an ideal method for insulation field.
A copolyimide (CPI) was prepared by a simple copolymerization process. The film possesses good self-healing ability based on disulfide bond exchange after mechanical/electrical damage and maintains high thermal stability and insulation property.
