Microwave absorption performance of methylimidazolium ionic liquids: towards novel ultra-wideband metamaterial absorbers

Gong, Jianhao; Yang, Fulong; Shao, Qunfeng; He, Xiaodong; Xiao-ping, Zhang; Liu, Shimin; Tang, Liyun; Deng, Yuanfu

doi:10.1039/c7ra06709g

Cited by 27 publications

(19 citation statements)

References 38 publications

(39 reference statements)

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“…The absorption at higher frequency presented the minimum RL for the sample with 2.5 phr of IL. The microwave absorption characteristic of these ER network loaded with IL may be attributed to the dielectric and conductive loss generated by the presence of free ions and anion–cation pairs, thus causing ionic conductivity and dielectric polarization . There is an optimum concentration of ions for the highest absorption of the radiation.…”

Section: Resultsmentioning

confidence: 99%

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Epoxy/imidazolium‐based ionic liquid systems: The effect of the hardener on the curing behavior, thermal stability, and microwave absorbing properties

Carvalho

Santos

Soares

2019

J of Applied Polymer Sci

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A new transparent microwave absorbing coating was developed by compounding 1-butyl-3-methyl imidazolium tetrafluoroborate (bmim.BF 4 ) ionic liquid (IL) with diglycidyl ether of bisphenol A-type epoxy resin. The systems were crosslinked with the IL alone or combined with conventional hardeners, as anhydride or aromatic amine. The curing behavior was investigated by thermal and spectroscopic analysis performed at high temperatures. Neat bmim.BF 4 was able to cure epoxy resin, giving rise to networks with outstanding thermal stability compared with the systems cured with anhydride or aromatic amine. bmim.BF 4 accelerated the curing process in the presence of aromatic amine but retarded this event when anhydride was used as an external curing agent. The glass-transition temperature evaluated by dynamic mechanical analysis decreased when the amount of IL increased, which can be attributed to side reactions during the curing process, as well as the plasticizing effect of IL. The epoxy networks cured with bmim.BF 4 alone or in combination with anhydride or aromatic amine were transparent and presented considerable microwave absorbing properties in the X-band frequency range (8-12 GHz), being the best performance observed for the systems cured with bmim.BF4/anhydride curing system, with reflection loss value around −16 dB at 11.3 GHz.

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Section: Resultsmentioning

confidence: 99%

“…However, they require some synthetic pathways which limits the scale‐up. Pure imidazolium‐based IL was recently reported to present strong microwave absorption in a broad microwave frequency range …”

Section: Introductionmentioning

confidence: 99%

Epoxy/imidazolium‐based ionic liquid systems: The effect of the hardener on the curing behavior, thermal stability, and microwave absorbing properties

Carvalho

Santos

Soares

2019

J of Applied Polymer Sci

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“…[64][65][66] Moreover, the ionic liquids have high dielectric-loss factors in the microwave range, which are desirable for fabricating microwave all-dielectric metamaterials. [67] The cavity injection method has been used to fabricate all-dielectric metamaterials based on ionic liquids. In one example, a 3D printer was employed to fabricate hollow annular groove unit cells.…”

Section: Cavity Injection Methodsmentioning

confidence: 99%

All‐Dielectric Metamaterial Fabrication Techniques

Wang

et al. 2020

Advanced Optical Materials

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region. Basically, all-dielectric metamaterials are composed of polymers, dielectrics, ferrites, or composite materials. [20-22] The unusual electromagnetic properties of all-dielectric metamaterials not only derive from their artificial structure, but also originate directly from the materials, revealing an approach to designing metamaterials with more freedom. [23] Since the initial proposal of all-dielectric metamaterials, various realization mechanisms have been studied and reported. [24-26] The most classical mechanism is based on the so-called Mie-resonance theory, and has been studied extensively. [27-29] In this strategy, dielectric particles with relatively high permittivity are used to generate strong magnetic or electric resonance through electromagnetic wave interaction. Therefore, a negative permeability or permittivity can be produced by the oscillation of the resulting magnetic or electric dipole. This mechanism is simple and versatile, and is generally adopted for the realization of all-dielectric metamaterials with low losses. [30] Ferromagnetic resonance (FMR) theory is another classical realization mechanism for all-dielectric metamaterials. [31,32] When the ferromagnetic resonance of the ferrite takes place, a negative permeability appears. Many factors can influence the FMR of the magnetic materials, including the bias magnetic field, magnetocrystalline anisotropy field, and demagnetization field. Hence, ferrite metamaterials with dual-band, multiband, or tunable properties can be obtained, providing a way to resolve the narrow band problem. Besides, mechanisms such as indefinite media or crystal lattice vibration have also been used to realize all-dielectric metamaterials. [33,34] When determining the realization mechanism for an all-dielectric metamaterial, one crucial factor must be considered: the choice of a fabrication method. Moreover, to achieve different performances, many types of materials with specific electromagnetic properties are used to prepare all-dielectric metamaterials. [35] Hence, researchers have developed various techniques for the fabrication of all-dielectric metamaterials derived from different materials. [36-40] In addition, the fabrication requirements are quite different for all-dielectric metamaterials operating at frequencies ranging from the microwave to optical regions. In particular, the size of the metamaterial unit cell is much smaller than the operational wavelength, making the fabrication technology for all-dielectric metamaterials become the key to their further application. Here, we present a comprehensive review of the various techniques used to produce all-dielectric metamaterials. We review the existing fabrication technologies for microwave, terahertz, and optical all-dielectric All-dielectric metamaterials with low loss are a rapidly developing research hotspot in the field of metamaterials, and offer additional design freedom for electromagnetic devices. Many types of fabrication techniques are used to prepare all-dielectric metamaterials, so as t...

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“…Therefore, it was conceivable that the interaction mechanism between GO and MWs would become more complicated when GO was functionalized with ILs. Because ILs could become strong absorbers of MWs because of their special polarization structure containing anion–cation pairs. − Recent literature surveys ,, clearly revealed that it was a relatively unexplored area of research referring to both the synthesis mechanism of the IL-GO hybrid and the microscale interaction between the IL-GO hybrid and polymer matrix under the function of MWs. Therefore, for the polymer-containing IL-GO hybrid, it was necessary to study its curing mechanism and overall performance under the action of MWs.…”

Section: Introductionmentioning

confidence: 99%

Ionic Liquid-Graphene Oxide for Strengthening Microwave Curing Epoxy Composites

Shi

Luo

Huan

et al. 2020

ACS Appl. Nano Mater.

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The challenge for fully exerting the excellent nature of graphene oxide (GO) within polymer composites was to realize its uniform dispersion and strong interfacial bonding in the polymer matrix through an efficient surface reduction approach. In this work, via the in situ activation effect of microwaves (MWs), a butyl glycidyl ether-modified ionic liquid (BIL)-GO hybrid was successfully synthesized at an ultrafast speed by introducing BIL into the two-dimensional lamellar structure of GO through chemically induced intercalation and noncovalent functions. Both GO and BIL components of BIL-GO had the positive synergism in absorbing MWs, which contributed much to enhancing its dispersibility in the epoxy (EP) matrix as compared with pristine GO. Superior to GO-filled systems, BIL-GO/EP composites showed lower activation energies (E a1 and E a2 reduced by 11.2 and 17.3%, respectively) over the range of cure following inside-out solidification modes because of the introduction of BIL because uniformly dispersed BIL-GO with exfoliated interlayers acted as trap centers of MWs. Additionally, BIL-GO/EP composites possessed a 22.1% increase in the strength of the transverse fiber bundle test over that of GO/EP composites, indicating better BIL-GO/EP interfacial bonding. The obtained results manifested that the advantageous effect of BIL through the in situ activation of MWs was to enhance the interface stress transfer and form a uniform BIL-GO network, thereby significantly enhancing the mechanical, thermal, and electrical properties of BIL-GO composites.

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Microwave absorption performance of methylimidazolium ionic liquids: towards novel ultra-wideband metamaterial absorbers

Abstract: The ultra-wideband absorption of microwaves was achieved by metamaterials based on methylimidazolium ionic liquids for the first time.

Cited by 27 publications

References 38 publications

Epoxy/imidazolium‐based ionic liquid systems: The effect of the hardener on the curing behavior, thermal stability, and microwave absorbing properties

Epoxy/imidazolium‐based ionic liquid systems: The effect of the hardener on the curing behavior, thermal stability, and microwave absorbing properties

All‐Dielectric Metamaterial Fabrication Techniques

Ionic Liquid-Graphene Oxide for Strengthening Microwave Curing Epoxy Composites

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