CN114914712A - Reconfigurable elastic wave absorber based on metal nanowire aerogel and preparation method thereof - Google Patents

Abstract

The invention discloses a reconfigurable elastic wave absorbing body based on metal nanowire aerogel, comprising from top to bottom: a first wave absorbing layer, a second wave absorbing layer and a metal nanowire backplane; a first wave absorbing layer The layer includes a first polymer elastomer dielectric layer and a first metal nanowire aerogel microstructure array wrapped therein; the second wave absorbing layer includes a second polymer elastomer dielectric layer and a second polymer elastomer dielectric layer wrapped therein Metal nanowire aerogel microstructure array; the first metal nanowire aerogel microstructure array includes a plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals; the second metal nanowire aerogel microstructure The structure array includes a plurality of second metal nanowire aerogel microstructures arranged periodically at equal intervals; the metal nanowire backplane is obtained by coating the surface of a polymer elastomer film with a metal nanowire dispersion. The invention can realize a broadband metamaterial wave absorbing body with simplified structure, flexible reconfiguration, tunable wave absorbing performance and excellent impedance matching characteristics.

Description

Reconfigurable elastic wave absorber based on metal nanowire aerogel and preparation method thereof

technical field

The invention belongs to the field of electromagnetic wave absorbers, in particular to a reconfigurable elastic wave absorber based on metal nanowire aerogel and a preparation method thereof.

Background technique

At present, with the increasing complexity of the electromagnetic environment, electromagnetic absorbers have a vigorous demand for stealth technology, electromagnetic protection, etc., and can be mainly used in aircraft, radar, integrated circuits, and wearable devices. However, in the development process of electromagnetic absorbers, it is difficult to tune their absorbing properties in real time because the absorbers based on rigid structures are fabricated. Therefore, the application of this type of electromagnetic wave absorber is limited to a certain extent, and it cannot achieve the most ideal electromagnetic protection effect, especially when it is applied to signal transmission systems such as radar, the effect is poor. At the same time, in practical engineering applications, when the rigid curved carrier is used for electromagnetic protection, the absorbing material needs to have good flexibility to meet the requirements of conformality. Therefore, the reconfigurable technology of electromagnetic wave absorbers has been widely concerned.

At present, the reconfigurable technology for electromagnetic wave absorbers mainly includes three research directions: 1. Change the characteristics of the lumped components of the wave absorbing system; this method mainly changes the parameters to tune. However, such complex active absorbers not only require complex and reasonable feeding networks to provide excitation for device operation, but also generally have rigid flat-plate structures, which cannot meet the conformal requirements of practical device applications. 2. Change the electromagnetic parameters of the absorber; this method mainly controls the electromagnetic parameters of the material inside the absorber through external excitation to realize the function of dynamic tuning. However, in most cases, this method cannot meet the requirements of surface conformality in modern engineering. 3. Change the mechanical structure parameters of the material; in this way, the absorber can be reconfigured by changing the interference path macroscopically, such as by mechanical stretching or extrusion. Compared with the first two methods, this method has a simpler structure of the wave absorber and is more convenient to adjust the peak value of the wave absorption. However, at present, conductive materials such as indium tin oxide are mostly used, which have poor tensile properties and cannot meet the needs of large-scale stretching. Therefore, on this basis, researchers have begun to work on the exploration and improvement of new absorbing materials.

Electromagnetic metamaterials that have emerged in recent years are electromagnetic media composed of artificial atoms or molecules (ie, artificially designed microstructures) that are periodically arranged. In the processing design, by continuously optimizing and improving the microstructure, metamaterials can exhibit different exotic electromagnetic phenomena at the macroscopic level. Especially in the field of electromagnetic wave absorption, compared with traditional wave absorption materials, electromagnetic metamaterials show the characteristics of light weight, small consumables and superior wave absorption performance. important use.

Therefore, how to design a broadband metamaterial absorber with simplified structure, flexible reconfiguration, tunable absorber performance and excellent impedance matching characteristics is a very important research direction in this field.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a reconfigurable elastic wave absorber based on metal nanowire aerogel and a preparation method thereof, so as to provide a simplified structure, flexible and reconfigurable, tunable wave absorption performance and excellent Impedance matching properties of broadband metamaterial absorbers for the purpose. The specific technical solutions are as follows:

In a first aspect, an embodiment of the present invention provides a reconfigurable elastic wave absorber based on a metal nanowire aerogel, including from top to bottom:

a first wave-absorbing layer, a second wave-absorbing layer and a metal nanowire backplane;

Wherein, the first wave-absorbing layer includes a first polymer elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first polymer elastomer medium layer; the second absorber The wave layer includes a second polymer elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second polymer elastomer medium layer; the first metal nanowire aerogel microstructure The array includes a plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals; the second metal nanowire aerogel microstructure array includes a plurality of second metal nanowire aerogels periodically arranged at equal intervals Adhesive microstructure; the metal nanowire backplane is obtained by coating the surface of a polymer elastomer film with a metal nanowire dispersion.

In an embodiment of the present invention, the polymer elastomer in the first polymer elastomer medium layer, the second polymer elastomer medium layer and the polymer elastomer film includes:

Polydimethylsiloxane PDMS, aliphatic aromatic random copolyester Ecoflex, waterborne polyurethane WPU, thermoplastic polyurethane rubber TPU and natural rubber NR.

In an embodiment of the present invention, the first metal nanowire aerogel microstructure, the second metal nanowire aerogel microstructure, and the metal nanowires in the metal nanowire dispersion include:

Gold nanowires, silver nanowires and copper nanowires.

In an embodiment of the present invention, the first metal nanowire aerogel microstructure and the second metal nanowire aerogel microstructure are patterned structures of metal nanowire aerogel.

In one embodiment of the present invention, the patterned structure includes a zigzag structure, an open resonance ring structure and a cross-shaped structure.

In an embodiment of the present invention, for the back-shaped structure:

The electrical conductivity of each first metal nanowire aerogel microstructure is 0.1-10 S/m; the side length of the outer square of the back-shaped structure is 12-16 mm; the side length of the inner square is 6-10 mm; the back-shaped structure The thickness of the first polymer elastomer medium layer is 1.6-2.0mm; the length of the first polymer elastomer medium layer is 13-23mm; the width of the first polymer elastomer medium layer is 13-23mm; the first polymer elastomer The thickness of the dielectric layer is 1.5 to 2 mm;

The electrical conductivity of each second metal nanowire aerogel microstructure is 0.1-10 S/m; the side length of the outer square of the back-shaped structure is 6-10 mm; the side length of the inner square is 1-5 mm; the back-shaped structure The thickness of the second polymer elastomer medium layer is 1.6-2.0mm; the length of the second polymer elastomer medium layer is 13-23mm; the width of the second polymer elastomer medium layer is 13-23mm; the second polymer elastomer The thickness of the dielectric layer is 1.5-2 mm.

In an embodiment of the present invention, for the split resonant ring structure:

The electrical conductivity of each first metal nanowire aerogel microstructure is 0.1-10 S/m; the outer radius of the open resonant ring structure is 6-8 mm; the inner radius is 3-5 mm; the length of the opening rectangle is 6-8 mm 10mm; the width of the open rectangle is 2-6mm; the vertical distance from the center of the circle to the far side of the open rectangle is 5-8mm; the thickness of the open resonant ring structure is 1.3-1.5mm; the length of the first polymer elastomer dielectric layer is 13-23mm; the width of the first polymer elastomer medium layer is 13-23mm; the thickness of the first polymer elastomer medium layer is 1.5-2mm;

The electrical conductivity of each second metal nanowire aerogel microstructure is 0.1-10 S/m; the outer radius of the open resonant ring structure is 3-5 mm; the inner radius is 0.5-2.5 mm; the length of the open rectangle is 2 ～6mm, the width of the open rectangle is 2～6mm, the vertical distance from the center of the circle to the far side of the open rectangle is 3～6mm; the thickness of the open resonant ring structure is 1.3～1.5mm; The length is 13-23 mm; the width of the second high-molecular elastomer medium layer is 13-23 mm; the thickness of the second high-molecular elastomer medium layer is 1.5-2 mm.

In an embodiment of the present invention, the electrical conductivity of the metal nanowire backplane is 10000-20000 S/m; the thickness is 0.1-0.3 mm; the concentration range of the coated metal nanowire dispersion liquid is 45 mg/ml-60 mg /ml.

In an embodiment of the present invention, the application frequency band of the metal nanowire aerogel-based reconfigurable elastic wave absorber includes:

X-band and Ku-band.

In a second aspect, an embodiment of the present invention provides a method for preparing a reconfigurable elastic wave absorber based on a metal nanowire aerogel, the method comprising:

Step 1, for the target wavelength band, obtain electromagnetic parameters of aerogel materials cast by metal nanowire dispersions of different concentrations at preset sampling intervals within a preset concentration range, and determine the range of each electromagnetic parameter; wherein, the electromagnetic parameters Including conductivity and dielectric constant;

Step 2, simulate and model the reconfigurable elastic wave absorber based on the metal nanowire aerogel, the structure of which includes from top to bottom: a first wave absorbing layer, a second wave absorbing layer and a polymer elastomer film; The first wave-absorbing layer includes a first high-molecular elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first high-molecular elastomer medium layer; the second wave-absorbing layer It includes a second polymer elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second polymer elastomer medium layer; the first metal nanowire aerogel microstructure array includes A plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals; the second metal nanowire aerogel microstructure array includes a plurality of second metal nanowire aerogel microstructures periodically arranged at equal intervals structure; and perform geometric parameter scanning and optimization on the reconfigurable elastic wave absorber based on metal nanowire aerogel obtained by simulation modeling to obtain the initial geometric parameters of the model;

Step 3: On the basis of the initial geometric parameters of the model, and based on the corresponding electromagnetic parameter range, scan the electrical parameters of the reconfigurable elastic wave absorber based on the metal nanowire aerogel, and determine the preferred value of each electromagnetic parameter ;

Step 4, according to the initial geometric parameters of the model and the preferred values of the electromagnetic parameters, use a freeze-drying process to prepare a corresponding patterned metal nanowire aerogel to obtain the first metal nanowire aerogel microstructure ; Use a plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals to form the first metal nanowire microstructure array, and wrap the first metal nanowire microstructure array around the first high The molecular elastomer dielectric layer forms the first wave absorbing layer;

Step 5, adjusting process parameters, repeating Step 4 to form the second wave absorbing layer;

Step 6: Suspend a metal nanowire dispersion with a predetermined concentration on the cured polymer elastomer film, and heat and dry to form a metal nanowire backplane;

Step 7: Laminate the prepared first wave absorbing layer, the second wave absorbing layer and the metal nanowire backplane in sequence from top to bottom to form the metal nanowire-based aerogel. Reconstructed elastic absorber.

Beneficial effects of the present invention:

In the embodiment of the present invention, a reconfigurable elastic wave absorber based on metal nanowire aerogel is designed by utilizing the excellent deformability of the aerogel high-elastomer compounded by the polymer elastomer. Construct the absorber. The three-layer conductive functional layers of the absorber are all made of metal nanowires, which have excellent stretchability, so that the absorber can maintain large-scale stretching as a whole, and can ensure the stability of mechanical deformation to the greatest extent. The wave filter has stable and reconfigurable performance.

Moreover, the embodiment of the present invention utilizes the aerogel porous structure to prepare the metamaterial structural unit. Since the metal nanowire porous aerogel is used, when the electromagnetic wave is incident on the surface of the aerogel, it will form a good impedance match with the voids on the surface of the aerogel, which can greatly enhance the probability of the electromagnetic wave entering the interior of the metamaterial. At the same time, the aerogel also acts as an electromagnetic wave absorber, so that when the electromagnetic wave passes through the inside of the aerogel, the abundant cell wall surface CWS in the aerogel can perform multiple reflection losses on the electromagnetic wave, thereby greatly enhancing the wave absorbing performance of the material. In addition, the abundant pores inside the aerogel also provide space for polymer elastomer filling, enabling the formation of multiphase composites.

In addition, the embodiment of the present invention uses a polymer elastomer to encapsulate the metal nanowire aerogel, which can greatly reduce the erosion of specific chemical substances in the environment, effectively prevent adverse chemical reactions of the metal nanowires, and greatly improve the metal nanowires. Stability of the conductive network of wire aerogels. At the same time, since the internal microporous structure of the metal nanowire aerogel is infiltrated in the polymer elastomer, the stability of the aerogel structure can also be enhanced and its tensile properties can be improved. In addition, the use of polymer elastomers can endow the wave absorber with elastic deformation ability, so that the wave absorber has good conformal ability, and can be easily and conveniently attached to the surface of the equipment requiring electromagnetic protection; at the same time, during the deformation process, the present invention The wave absorber of the embodiment has high mechanical stability and good flexibility, and can be bent, twisted or even stretched arbitrarily, and can meet the requirements of different electromagnetic wave absorption and protection requirements and the requirements of repeated use in a wide frequency band.

Description of drawings

1 is a schematic side view of a structure of a reconfigurable elastic wave absorber based on a metal nanowire aerogel according to an embodiment of the present invention;

FIG. 2 is a schematic plan view of a metal nanowire aerogel microstructure with a zigzag structure according to an embodiment of the present invention;

3 is an exploded diagram of a reconfigurable elastic wave absorber based on a metal nanowire aerogel, which is exemplified by a group of metal nanowire aerogel microstructures with a zigzag structure according to an embodiment of the present invention;

FIG. 4 is a top view of a reconfigurable elastic wave absorber based on a metal nanowire aerogel, which is exemplified by a group of metal nanowire aerogel microstructures with a zigzag structure according to an embodiment of the present invention;

5 is a top view of a reconfigurable elastic wave absorber based on a metal nanowire aerogel exemplified by a metal nanowire aerogel microstructure array with a zigzag structure according to an embodiment of the present invention;

6 is a schematic plan view of a metal nanowire aerogel microstructure of an open resonant ring structure according to an embodiment of the present invention;

7 is a top view of a group of metal nanowire aerogel microstructures of an open resonant ring structure according to an embodiment of the present invention;

8 is a comparison diagram of the absorption efficiency of a traditional metamaterial wave absorber with a patterned structure and a reconfigurable elastic wave absorber based on a metal nanowire aerogel according to an embodiment of the present invention;

Figure 9 is a SEM image (scanning electron image) of silver nanowire aerogel;

10 is a diagram of the frequency-reconfigurable absorption efficiency of a metal nanowire aerogel-based reconfigurable elastic wave absorber based on a zigzag structure, calculated by using a finite element method according to an embodiment of the present invention;

11 is a diagram of the frequency-reconfigurable absorption efficiency of the metal nanowire aerogel-based reconfigurable elastic wave absorber based on the split resonant ring structure calculated by the finite element method according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to facilitate the understanding of the solutions of the embodiments of the present invention, the inventive concept of the embodiments of the present invention is briefly introduced first.

At present, new porous materials represented by aerogels have begun to emerge in the field of electromagnetic wave absorption. The new absorber prepared from this low-dimensional material has a unique three-dimensional network structure, high specific surface area, low density and other advantages, which can realize the construction of high-efficiency conductive network under the condition of low filling amount, and then endow the material with strong electromagnetic wave attenuation. ability. And the rich pore structure of porous materials not only lays an important structural foundation for electromagnetic parameter regulation and impedance matching optimization, but also provides the possibility for materials to backfill polymer elastomers and improve their tensile and compressive properties. Therefore, the present invention contemplates the preparation of reconfigurable metamaterials using aerogel-structured elastomers. In this way, not only can the absorbing performance be controlled macroscopically, but also the impedance matching characteristics of the material can be optimized on the basis of giving the material elasticity to enhance the absorbing performance.

After in-depth research, in order to achieve the purpose of designing a broadband metamaterial wave absorber with simplified structure, flexible reconfiguration, tunable wave absorption performance and excellent impedance matching characteristics, the embodiment of the present invention provides a metal nanowire-based absorber. Reconfigurable elastic wave absorber of aerogel and preparation method thereof.

In the following, a reconfigurable elastic wave absorber based on a metal nanowire aerogel provided by an embodiment of the present invention is first introduced. As shown in FIG. 1 , FIG. 1 is a schematic side view structure diagram of a reconfigurable elastic wave absorber based on a metal nanowire aerogel provided by an embodiment of the present invention. The reconfigurable elastic wave absorber based on metal nanowire aerogel provided by the embodiment of the present invention includes, from top to bottom:

a first wave-absorbing layer, a second wave-absorbing layer and a metal nanowire backplane;

Wherein, the first wave-absorbing layer includes a first polymer elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first polymer elastomer medium layer; the second absorber The wave layer includes a second polymer elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second polymer elastomer medium layer; the first metal nanowire aerogel microstructure The array includes a plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals; the second metal nanowire aerogel microstructure array includes a plurality of second metal nanowire aerogels periodically arranged at equal intervals Adhesive microstructure; the metal nanowire backplane is obtained by coating the surface of a polymer elastomer film with a metal nanowire dispersion.

In FIG. 1, 110 represents the first wave absorbing layer; 120 represents the second wave absorbing layer; 130 represents the metal nanowire backplane; 1101 represents the first polymer elastomer dielectric layer; 1102 represents the first metal nanowire aerogel Microstructure; 1201 represents the second polymer elastomer medium layer; 1202 represents the second metal nanowire aerogel microstructure.

Wherein, the first wave absorbing layer, the second wave absorbing layer and the metal nanowire backplane are laminated in sequence from top to bottom to form the reconfigurable elastic wave absorber based on the metal nanowire aerogel . In order to facilitate preparation and tuning, the first polymer elastomer medium layer, the second polymer elastomer medium layer and the polymer elastomer film use the same polymer elastomer; the first metal nanometer The wire aerogel microstructure, the second metal nanowire aerogel microstructure and the metal nanowire dispersion are prepared from the same metal. Reasonable choice.

In an optional embodiment, the polymer elastomer in the first polymer elastomer medium layer, the second polymer elastomer medium layer and the polymer elastomer film includes:

Polydimethylsiloxane PDMS, aliphatic aromatic random copolyester Ecoflex, waterborne polyurethane WPU, thermoplastic polyurethane rubber TPU and natural rubber (NR).

It can be understood that the polymer elastomer in the embodiment of the present invention can endow the wave absorber with the ability to deform, so as to ensure that the wave absorber has good conformal ability, so that the wave absorber can be easily and conveniently attached to the equipment that needs electromagnetic protection. At the same time, in the process of deformation, because it can be bent, twisted or even stretched arbitrarily, it can ensure that the absorber has high mechanical stability and good flexibility. At the same time, in the embodiment of the present invention, the polymer elastomer is used to encapsulate the metal nanowire aerogel in the wave absorber, which can greatly reduce the chemical emissions of hydrogen sulfide H ₂ S, carbonyl sulfide OCS, nitric acid HNO ₃ and water oxygen in the environment. The erosion of substances can effectively prevent the metal nanowires from being vulcanized and other adverse chemical reactions, and can greatly improve the stability of the conductive network of the metal nanowire aerogel. And because the internal microporous structure of the metal nanowire aerogel is infiltrated in the polymer elastomer, the stability of the aerogel structure can also be enhanced and the tensile properties can be improved.

In an optional embodiment, the first metal nanowire aerogel microstructure, the second metal nanowire aerogel microstructure, and the metal nanowires in the metal nanowire dispersion include:

Gold nanowires, silver nanowires and copper nanowires.

The preparation and acquisition process of metal nanowires belong to the prior art, and will not be described in detail here.

In the embodiment of the present invention, the first wave absorbing layer, the second wave absorbing layer and the metal nanowire backplane form three layers of conductive functional layers, all of which are made of metal nanowires, and all have excellent stretchability, making the wave absorbing The body as a whole can maintain large-scale stretch. In this way, the stability of the mechanical deformation of the wave absorber can be ensured to the greatest extent, so that the wave absorber has stable reconfigurability.

At the same time, due to the use of porous materials such as metal nanowire aerogels, when electromagnetic waves are incident on the surface of metal nanowire aerogels, a better impedance match will be formed with the surface voids, which greatly enhances the incidence of electromagnetic waves entering the material. probability. At the same time, the metal nanowire aerogel also acts as an electromagnetic wave absorber, so that when the electromagnetic wave passes through the inside of the metal nanowire aerogel, the abundant cell wall surface CWS can carry out multiple reflection losses on the electromagnetic wave, thereby greatly enhancing the absorption of the material. wave performance. In addition, the abundant pores inside the metal nanowire aerogel also provide space for polymer elastomer filling, which can form multiphase composites.

In the embodiment of the present invention, the first metal nanowire aerogel microstructure and the second metal nanowire aerogel microstructure are patterned structures of metal nanowire aerogel. In the embodiment of the present invention, the metamaterial is formed by patterning the aerogel porous structure, which fills a blank in the invention and research of the high-loss electromagnetic wave absorber. In the embodiments of the present invention, various patterned structures with voids in the interior or voids in the edges can be designed as required.

For example, in an optional implementation manner, the patterned structure may include a back-shaped structure, an open resonance ring structure, a cross-shaped structure, and the like. It can be understood that the back-shaped structure, the open resonance ring structure and the cross-shaped structure refer to the planar shape of the patterned structure. In fact, the patterned structure has a certain thickness. In the side view of FIG. A rectangle is used as an example of a side view of the graphic structure, but not as a limitation on its structural form. Of course, the graphical structure of the embodiment of the present invention is not limited to the above three forms.

It should be noted that, due to the existence of the first polymer elastomer medium layer and the second polymer elastomer medium layer, the lower surface of the first metal nanowire aerogel microstructure and the second metal nanowire aerogel microstructure are not in direct contact with the top surface.

In the embodiment of the present invention, a reconfigurable elastic wave absorber based on metal nanowire aerogel is designed by utilizing the excellent deformability of the aerogel high-elastomer compounded by the polymer elastomer. Construct the absorber. The three-layer conductive functional layers of the absorber are all made of metal nanowires, which have excellent stretchability, so that the absorber can maintain large-scale stretching as a whole, and can ensure the stability of mechanical deformation to the greatest extent. The wave filter has stable and reconfigurable performance.

Moreover, the embodiment of the present invention utilizes the aerogel porous structure to prepare the metamaterial structural unit. Since the metal nanowire porous aerogel is used, when the electromagnetic wave is incident on the surface of the aerogel, it will form a good impedance match with the voids on the surface of the aerogel, which can greatly enhance the probability of the electromagnetic wave entering the interior of the metamaterial. At the same time, the aerogel also acts as an electromagnetic wave absorber, so that when the electromagnetic wave passes through the inside of the aerogel, the abundant cell wall surface CWS in the aerogel can perform multiple reflection losses on the electromagnetic wave, thereby greatly enhancing the wave absorbing performance of the material. In addition, the abundant pores inside the aerogel also provide space for polymer elastomer filling, enabling the formation of multiphase composites.

In addition, the embodiment of the present invention uses a polymer elastomer to encapsulate the metal nanowire aerogel, which can greatly reduce the erosion of specific chemical substances in the environment, effectively prevent adverse chemical reactions of the metal nanowires, and greatly improve the metal nanowires. Stability of the conductive network of wire aerogels. At the same time, since the internal microporous structure of the metal nanowire aerogel is infiltrated in the polymer elastomer, the stability of the aerogel structure can also be enhanced and its tensile properties can be improved. In addition, the use of polymer elastomers can endow the wave absorber with elastic deformation ability, so that the wave absorber has good conformal ability, and can be easily and conveniently attached to the surface of the equipment requiring electromagnetic protection; at the same time, during the deformation process, the present invention The wave absorber of the embodiment has high mechanical stability and good flexibility, and can be bent, twisted or even stretched arbitrarily, and can meet the requirements of different electromagnetic wave absorption and protection requirements and the requirements of repeated use in a wide frequency band.

The following describes the parameter ranges of the reconfigurable elastic wave absorber based on metal nanowire aerogel in the embodiment of the present invention in combination with two different graphical structures. The following optional parameter values use a large number of metal nanowires with different concentrations. The wire dispersion corresponds to the cast aerogel test sample data, which is obtained by optimizing the simulation modeling parameters. For details, please refer to the second aspect of the preparation method of the reconfigurable elastic wave absorber based on metal nanowire aerogel. content.

(1) Back-shaped structure

Please refer to FIG. 2 for the plane structure diagram of the first metal nanowire aerogel microstructure or the second metal nanowire aerogel microstructure of the zigzag structure, and FIG. 2 is the metal nanowire aerogel of the zigzag structure according to the embodiment of the present invention. Schematic plan view of the glue microstructure. The back-shaped structure is a ring structure composed of two squares with different inner and outer side lengths, and has a certain thickness when used as the first metal nanowire aerogel microstructure or the second metal nanowire aerogel microstructure, and the The hollow area in the back-shaped structure is filled with a polymer elastomer medium.

FIG. 3 is an exploded diagram of a reconfigurable elastic wave absorber based on a metal nanowire aerogel, which is exemplified by a group of metal nanowire aerogel microstructures with a zigzag structure according to an embodiment of the present invention. FIG. 4 is a top view of a reconfigurable elastic wave absorber based on a metal nanowire aerogel, which is exemplified by a group of metal nanowire aerogel microstructures with a zigzag structure according to an embodiment of the present invention. FIG. 5 is a top view of a reconfigurable elastic wave absorber based on a metal nanowire aerogel, which is exemplified by a metal nanowire aerogel microstructure array with a zigzag structure according to an embodiment of the present invention. It can be understood that the nested zigzags in FIG. 4 and FIG. 5 are the top-view overlapping effect of the first metal nanowire aerogel microstructure and the second metal nanowire aerogel microstructure.

In an optional implementation manner, for the back-shaped structure:

The electrical conductivity σ ₁ of each first metal nanowire aerogel microstructure is 0.1-10 S/m; the side length a ₁ of the outer square of the zigzag structure is 12-16 mm; the side length a ₂ of the inner square is 6 ～10mm; the thickness d1 _of the back-shaped structure is 1.6～2.0mm; the length _l1 of the first polymer elastomer medium layer is 13～23mm; the width w1 of the _first polymer elastomer medium layer is 13 to 23 mm; the thickness h ₁ of the first polymer elastomer medium layer is 1.5 to 2 mm;

The electrical conductivity σ ₂ of each second metal nanowire aerogel microstructure is 0.1-10 S/m; the side length b ₁ of the outer square of the zigzag structure is 6-10 mm; the side length b ₂ of the inner square is 1 ~5mm; the thickness _d2 of the back-shaped structure is 1.6~2.0mm; the length _l2 of the second polymer elastomer medium layer is 13~23mm; the width w2 of the _second polymer elastomer medium layer is 13-23 mm; the thickness h ₂ of the second polymer elastomer medium layer is 1.5-2 mm.

The range of the interval parameters x ₁ , y ₁ , x ₂ , and y ₂ of the back-shaped structure is equal, and all are 5-8 mm, wherein each interval parameter is defined as: x ₁ =(l ₁ -a ₁ )/2; y ₁ =(w ₁ -a ₁ )/2; x ₂ =(l ₂ -a ₂ )/2; y ₂ =(w ₂ -a ₂ )/2, for simplicity, the above interval parameters will not be illustrated , please understand in conjunction with Figure 3 and Figure 4.

In a preferred embodiment, σ ₁ =σ ₂ =2S/m;σ ₃ =10000S/m;a ₁ =15mm;a ₂ =9mm;d ₁ =1.95mm;l ₁ =l ₂ =18mm;w ₁ = w ₂ =18mm; h ₁ =h ₂ = _2mm ;b ₁ =9mm;b _{2 =} 3.75mm;d _{2 =} 1.95mm;d ₃ =0.1mm _; 6mm.

(2) Open resonance ring structure

Please refer to FIG. 6 for a plane structure diagram of the first metal nanowire aerogel microstructure or the second metal nanowire aerogel microstructure of the open resonant ring structure, and FIG. 6 is the metal nanowire of the open resonant ring structure according to the embodiment of the present invention. Schematic plan view of the aerogel microstructure. The open resonance ring structure is an open ring structure composed of two concentric circles with different inner and outer radii, the opening directions of the two circles are the same, and the shape of the opening is a rectangle. The open resonant annular structure has a certain thickness when used as the first metal nanowire aerogel microstructure or the second metal nanowire aerogel microstructure, and the hollow region in the open resonant annular structure is filled with a polymer elastomer medium .

7 is a top view of a group of metal nanowire aerogel microstructures of an open resonant ring structure according to an embodiment of the present invention. It can be understood that the nested open resonant ring structure in FIG. 7 is a top-view overlapping effect of the first metal nanowire aerogel microstructure and the second metal nanowire aerogel microstructure.

In an optional implementation manner, for the open resonant ring structure:

The electrical conductivity σ ₁ of each first metal nanowire aerogel microstructure is 0.1-10 S/m; the outer radius c ₁ of the open resonant ring structure is 6-8 mm; the inner radius c ₂ is 3-5 mm; The length n ₁ of the opening rectangle is 6-10mm; the width m ₁ of the opening rectangle is 2-6mm; the vertical distance f ₁ from the center of the circle to the far side of the opening rectangle is 5-8mm; the thickness d ₁ of the opening resonant ring structure is 1.3-1.5 mm; the length l ₁ of the first macromolecular elastomer medium layer is 13-23 mm; the width w ₁ of the first macromolecular elastomer medium layer is 13-23 mm; the first macromolecular elastomer medium layer The thickness _h1 is 1.5～2mm;

The electrical conductivity σ ₂ of each second metal nanowire aerogel microstructure is 0.1-10 S/m; the outer radius e ₁ of the open resonant annular structure is 3-5 mm; the inner radius e ₂ is 0.5-2.5 mm , the length n ₂ of the opening rectangle is 2～6mm, the width m ₂ of the opening rectangle is 2～6mm, the vertical distance f ₂ from the center to the far side of the opening rectangle is 3～6mm; the thickness d ₂ of the opening resonant ring structure is 1.3～6mm 1.5 mm; the length l ₁ of the first polymer elastomer medium layer is 13-23 mm; the width w ₁ of the first polymer elastomer medium layer is 13-23 mm; the second polymer elastomer medium The thickness h ₂ of the layer is 1.5 to 2 mm.

The interval parameter x ₁ ′ of the open resonant ring structure represents the minimum horizontal distance between the left edge of the outer circle in the first metal nanowire aerogel microstructure and the left side of the rectangle corresponding to the first polymer elastomer dielectric layer; The interval parameter x ₂ ' represents the minimum horizontal distance between the right edge of the outer circle in the first metal nanowire aerogel microstructure and the right side of the rectangle corresponding to the first polymer elastomer dielectric layer; the interval parameter y ₁ ' represents the first A minimum vertical distance between the upper edge of the outer circle in the metal nanowire aerogel microstructure and the upper side of the rectangle corresponding to the first polymer elastomer dielectric layer; the interval parameter y ₂ ' represents the first metal nanowire aerogel The minimum vertical distance between the lower side edge of the outer circle in the microstructure and the lower side edge of the rectangle corresponding to the first polymer elastomer medium layer. The ranges of x ₁ ', x ₂ ', y ₁ ', and y ₂ ' are equal, and they are all 5-8 mm. For simplicity, the above-mentioned interval parameters are no longer illustrated, please understand with reference to FIG. 7 .

In a preferred embodiment, σ ₁ =σ ₂ =0.5S/m;σ ₃ =10000S/m; c ₁ =7.5mm;c ₂ =4.5mm;e ₁ =4.5mm;e ₂ =2mm;d ₁ = d ₂ =1.3mm; l ₁ =l ₂ =18mm; w ₁ =w ₂ =18mm;h ₁ =h ₂ =1.5mm;n ₁ =8mm;m ₁ =3.8mm;f ₁ =7.6mm;n ₂ =5mm; _m2 =3.7mm; f2=4.5mm _; interval parameter x1'= _y1 '= _x2 '= _y2 ' ₌ 5mm.

For the above two patterned structures, in an optional embodiment, the electrical conductivity σ3 _of the metal nanowire backplane is 10000-20000 S/m; the thickness _d3 is 0.1-0.3 mm; the coated metal nanowires The concentration range of the thread dispersion liquid is 45 mg/ml to 60 mg/ml. It is understood that this concentration range is already a relatively high concentration range.

In an optional embodiment, the application frequency band of the metal nanowire aerogel-based reconfigurable elastic wave absorber includes:

X-band and Ku-band.

Among them, it is known that the X-band is 8-12GHz and the Ku-band is 12-18GHz.

In the embodiment of the present invention, through experiments, the thickness of the relevant structures in the reconfigurable elastic wave absorber based on the metal nanowire aerogel is adjusted, for example, the original thickness value is changed by 1um to 10mm, which can cover GHz and part of the terahertz frequency band. For example, 0.2-2.0THz can meet the needs of wider frequency bands.

The performance effect of the reconfigurable elastic wave absorber based on the metal nanowire aerogel according to the embodiment of the present invention will be described below with reference to specific materials and parameters.

(1) Back-shaped structure, the metal is silver, the polymer elastomer is Ecoflex, and the frequency range is 8 to 12 GHz:

First, referring to Figure 3 and Figure 4, two silver plates with a thickness of 2 mm were processed into a back-shaped structure by an engraving machine, and the two were immersed in the solution of the polymer elastomer Ecoflex, and heated and cured to obtain two absorbing layers. And 0.5mm thick silver plate was assembled from bottom to top to obtain a traditional metamaterial absorber with a patterned structure, that is, a solid structure absorber.

According to the method of the embodiment of the present invention, using silver nanowires and Ecoflex, a reconfigurable elastic wave absorber based on metal nanowire aerogel with the same size as the above solid structure wave absorber was prepared according to 3 and FIG. 4 . The absorption efficiencies of the two absorbers are compared, and the results are shown in Figure 8. FIG. 8 is a comparison diagram of the absorption efficiency of a traditional metamaterial wave absorber with a patterned structure and a reconfigurable elastic wave absorber based on a metal nanowire aerogel according to an embodiment of the present invention. In Fig. 8, the horizontal axis represents the frequency; the vertical axis represents the reflection loss; the dotted line conventional structure represents the traditional metamaterial absorber with a patterned structure; the solid line aerogel structure represents the aerogel structure, that is, the embodiment of the present invention is based on metal nanowires Reconfigurable elastic absorbers of aerogels.

It can be seen from the comparison that the traditional metamaterial absorber with a patterned structure resonates at around 8 GHz, but the maximum reflection loss is -10 dB, which basically does not meet the wave absorption requirements. However, the reconfigurable elastic wave absorber based on metal nanowire aerogel prepared in the embodiment of the present invention has rich pore structure. By adjusting the porosity of the wave absorber, it has excellent electromagnetic wave absorption ability and maximum reflection. The loss is -39.8dB (that is, absorbing about 99.99% of electromagnetic waves), the absorbing frequency band (that is, the band where the reflection loss is less than -10dB) is 6.7GHz, and the frequency is 7.1GHz-13.8GHz, basically covering the X-band (about 8-12GHz) . This confirms that the porous structure aerogel has better impedance matching characteristics, which can maximize the absorption performance of the absorber compared with the traditional structure.

(2) Back-shaped structure, the metal nanowires are silver nanowires, the polymer elastomer is Ecoflex, and the frequency range is 8-12GHz:

3 and 9, FIG. 9 is a SEM image (scanning electron image) of the silver nanowire aerogel. The aerogel is cast with silver nanowires, the polymer elastomer is Ecoflex with excellent tensile properties, and the aerogel structure adopts a back-shaped structure.

After preparing the reconfigurable elastic wave absorber based on the metal nanowire aerogel according to the above steps, the prepared wave absorber is subjected to different degrees of mechanical transformation, and the performance of the wave absorber in different states is tested. Due to the changes of the functional microsurface structure, internal void morphology and thickness of the functional microstructure, the absorbing amplitude changes accordingly, and the absorbing peak frequency produces a blue-shift or a red-shift. The relevant performance is simulated and tested, and the results are shown in Figure 10. FIG. 10 is a diagram of the frequency-reconfigurable absorption efficiency of the metal nanowire aerogel-based reconfigurable elastic wave absorber based on the zigzag structure calculated by the finite element method according to an embodiment of the present invention.

Referring to FIG. 10 , an embodiment of the present invention provides a reconfigurable elastic wave absorber based on metal nanowire aerogel to provide three electromagnetic parameter curves in common working modes. By mechanically stretching the absorber structure to different degrees, The peak frequency of the central absorption wave is changed around 9GHz, 10GHz, and 11GHz, which can control the switching of three different working states, and always maintain the best electromagnetic wave absorption, so that the absorber can meet the absorption requirements to the greatest extent. In Fig. 9, stretch 0%, stretch 50%, and stretch 100% represent no deformation, stretch 50%, and stretch 100%, respectively.

1) When it is not deformed, the absorbing body maintains its original state, the peak frequency of the absorbing center is about 9GHz, the maximum reflection loss is -39.8dB (that is, absorbing about 99.99% of electromagnetic waves), and the absorbing frequency band (that is, the reflection loss is less than - 10dB band) is 3.7GHz, and the frequency is between 7.3GHz and 11GHz;

2) When the absorber is stretched by 50%, the peak frequency of the center of the absorber is about 10GHz, the maximum reflection loss is -20.6dB (that is, absorbing 99.13% of electromagnetic waves), and the frequency of the absorber is 3.9GHz, and the frequency is 8.3GHz～ 12.2GHz;

3) When the absorber is stretched by 100%, the peak frequency of the center of the absorber is about 11GHz, the maximum reflection loss is -15.6dB (that is, 97.23% of electromagnetic waves are absorbed), and the frequency of the absorber is 4.5GHz, and the frequency is 9.2GHz～13.8 GHz.

(3) Open resonant ring structure, the metal nanowires are copper nanowires, the polymer elastomer is PDMS, and the frequency range is 12-18GHz:

Referring to FIG. 7 , copper nanowires are used to cast aerogels for metal nanowires, PDMS is used for polymer elastomers, and an open resonant ring structure is used for aerogel structures to prepare a reconfigurable elastic wave absorber based on metal nanowire aerogels, The maximum reflection loss of the absorber is -42.91dB (that is, absorbing about 99.99% of electromagnetic waves), the absorbing frequency band (that is, the band with the reflection loss less than -10dB) is 9.7GHz, and the frequency is 11.6GHz ~ 21.3GHz, completely covering the Ku band ( about 12 to 18 GHz).

After preparing the reconfigurable elastic wave absorber based on the metal nanowire aerogel, the prepared wave absorber was subjected to different degrees of mechanical transformation, and the performance of the wave absorber in different states was tested. Due to the changes of the functional microsurface structure, internal void morphology and thickness of the functional microstructure, the absorbing amplitude changes accordingly, and the absorbing peak frequency produces a blue-shift or a red-shift. The relevant performance is simulated and tested, and the results are shown in Figure 11. 11 is a diagram of the frequency-reconfigurable absorption efficiency of the metal nanowire aerogel-based reconfigurable elastic wave absorber based on the split resonant ring structure calculated by the finite element method according to an embodiment of the present invention.

Referring to FIG. 11, the embodiment of the present invention provides a reconfigurable elastic wave absorber based on metal nanowire aerogel to provide three electromagnetic parameter curves in common working modes. By mechanically stretching the absorber structure to different degrees, The peak frequency of the central absorption wave is changed around 14GHz, 14.5GHz, and 16GHz, which can control the switching of three different working states, and always maintain the best electromagnetic wave absorption, so that the absorber can meet the absorption requirements to the greatest extent. In Fig. 11, stretch 0%, stretch 10%, and stretch 30% represent no deformation, stretch 10%, and stretch 30%, respectively.

1) When it is not deformed, the absorbing body remains in its original state, the peak frequency of the absorbing center is about 14GHz, the maximum reflection loss is -31.3dB (that is, absorbing about 99.93% of electromagnetic waves), and the absorbing frequency band (that is, the reflection loss is less than - 10dB band) is 9.7GHz, and the frequency is 11.6GHz ~ 21.3GHz;

2) When the absorber is stretched by 10%, the peak frequency of the center of the absorber is about 14.5GHz, the maximum reflection loss is -28.4dB (that is, 99.86% of the electromagnetic wave is absorbed), and the frequency of the absorber is 9.3GHz and the frequency is 11.9GHz ~21.2GHz;

3) When the absorber is stretched by 30%, the peak frequency of the center of the absorber is about 16GHz, the maximum reflection loss is -42.9dB (that is, absorbing 99.99% of electromagnetic waves), and the frequency of the absorber is 8.8GHz, and the frequency is 12.3GHz～21.1 GHz.

To sum up, the embodiments of the present invention use metal nanowire aerogels to prepare metamaterials with periodic microstructures, and propose a simple high-efficiency wave absorber that can be reconfigured by mechanical stretching. Specifically, the porous structure of aerogels is used to prepare The metamaterial unit can greatly improve the wave absorbing performance; meanwhile, the use of polymer elastomers to encapsulate the aerogel can improve the tensile performance and stability. The embodiment of the present invention can realize elastic reconfigurability (ie, the whole can be stretched and compressed), and can be used to realize real-time independent tunable broadband absorption in a wide frequency band such as X-band and Ku-band. By stretching and deforming, changing the shape and thickness of the microstructure of the absorber can flexibly realize the dynamic adjustment of the resonance frequency, and then cover the corresponding frequency band with a high absorption rate;

In the second aspect, corresponding to the reconfigurable elastic wave absorber based on the metal nanowire aerogel provided in the first aspect, an embodiment of the present invention further provides a reconfigurable elastic wave absorber based on the metal nanowire aerogel The preparation method of the body, the method comprises the following steps:

Step 1, for the target wavelength band, obtain electromagnetic parameters of aerogel materials cast by metal nanowire dispersions of different concentrations at preset sampling intervals within a preset concentration range, and determine the range of each electromagnetic parameter; wherein, the electromagnetic parameters Including conductivity and dielectric constant;

Specifically, the target band may be an X-band, a Ku-band, or the like. The preset concentration range can be 5mg/ml～20mg/ml and so on. The preset sampling interval can be 5 mg/ml or the like. The metal nanowires may be gold nanowires, silver nanowires, copper nanowires, and the like. Please refer to the prior art for the specific process of casting the aerogel material by using the metal nanowire dispersion, which will not be described here.

The electromagnetic parameters of various cast aerogel materials can be measured by the four-probe method and the Nicolson-Ross-Weir (NRW) method, so as to determine the parameter ranges corresponding to the conductivity and permittivity in each case, as Sweep range of electromagnetic parameters in subsequent simulations.

Step 2, simulate and model the reconfigurable elastic wave absorber based on the metal nanowire aerogel, the structure of which includes from top to bottom: a first wave absorbing layer, a second wave absorbing layer and a polymer elastomer film; The first wave-absorbing layer includes a first high-molecular elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first high-molecular elastomer medium layer; the second wave-absorbing layer It includes a second polymer elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second polymer elastomer medium layer; the first metal nanowire aerogel microstructure array includes A plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals; the second metal nanowire aerogel microstructure array includes a plurality of second metal nanowire aerogel microstructures periodically arranged at equal intervals structure; and perform geometric parameter scanning and optimization on the reconfigurable elastic wave absorber based on metal nanowire aerogel obtained by simulation modeling to obtain the initial geometric parameters of the model;

Specifically, the simulation modeling may adopt the finite element method FEM, the finite integral time domain CST, or the finite difference time domain FDTD, or the like. The first metal nanowire microstructure and the second metal nanowire microstructure may adopt a patterned structure such as a zigzag structure or a split resonant ring structure. Set the size of the first metal nanowire microstructure, the size of the second metal nanowire microstructure, the spacing of the metal nanowire microstructure, the thickness of the first polymer elastomer medium layer, the thickness of the second polymer elastomer medium layer, and the polymer elasticity _The scanning range _of various geometric parameters such as the size _of the bulk film, and then _optimize the parameters to obtain the _{optimal geometric parameters} . , l ₁ , l ₂ , w ₁ , w ₂ , h ₁ , h ₂ , interval parameters x ₁ , y ₁ , x ₂ , y ₂ and other parameters to determine the geometric parameters of the absorber.

During the simulation modeling, the _Floquet periodic boundary condition is used to simulate the structure _of the absorber array. According to the step of 1S/m, the samples are taken at equal intervals, and the metal nanowire backplane is replaced by the ideal electrical conductor boundary conditions. The optimal parameters of the absorber are obtained by simulation calculation, which provides theoretical guidance for the next preparation.

Step 3: On the basis of the initial geometric parameters of the model, and based on the corresponding electromagnetic parameter range, scan the electrical parameters of the reconfigurable elastic wave absorber based on the metal nanowire aerogel, and determine the preferred value of each electromagnetic parameter ;

On the basis of the geometric structure in step 2, according to the parameter ranges corresponding to the electrical conductivity and the dielectric constant determined in step 1, parameter sweep optimization is performed to determine the preferred values of σ ₁ , σ ₂ , and σ ₃ .

Step 4, according to the initial geometric parameters of the model and the preferred values of the electromagnetic parameters, use a freeze-drying process to prepare a corresponding patterned metal nanowire aerogel to obtain the first metal nanowire aerogel microstructure ; Use a plurality of first metal nanowire aerogel microstructures arranged periodically at equal intervals to form the first metal nanowire microstructure array, and wrap the first metal nanowire microstructure array around the first high The molecular elastomer dielectric layer forms the first wave absorbing layer;

Specifically, for example, for the zigzag structure, according to the parameter values determined in steps 2 and 3 for each structure in the first wave absorbing layer, a freeze-drying process is used to prepare a plurality of metal nanowire aerogels with zigzag structure, and then The macromolecular elastomer is infused with vacuum filtration, heated and dried to form a first metal nanowire microstructure and a corresponding array, and then a first wave absorbing layer is obtained by wrapping a macromolecular elastomer medium layer.

Step 5, adjusting process parameters, repeating Step 4 to form the second wave absorbing layer;

This step is similar to step 4, but is realized by adjusting process parameters according to the parameter values determined in steps 2 and 3 for each structure in the second wave absorbing layer.

Step 6: Suspend a metal nanowire dispersion with a predetermined concentration on the cured polymer elastomer film, and heat and dry to form a metal nanowire backplane;

Wherein, the preset concentration can be 45mg/ml～60mg/ml, 50～100mg/ml, etc., which is selected according to needs. The metal in the metal nanowire dispersion is the same as the metal in the first metal nanowire microstructure and the second metal nanowire microstructure.

Step 7: Laminate the prepared first wave absorbing layer, the second wave absorbing layer and the metal nanowire backplane in sequence from top to bottom to form the metal nanowire-based aerogel. Reconstructed elastic absorber.

In the preparation method of the reconfigurable elastic wave absorber based on metal nanowire aerogel provided by the embodiment of the present invention, the electromagnetic parameter test is firstly performed on the aerogel material cast by the dispersion liquid of metal nanowires of different concentrations, which is a follow-up The simulation provides a diverse and accurate scanning range; secondly, a simulation model of a reconfigurable elastic wave absorber based on metal nanowire aerogel is established, and the initial geometric parameters of the model are determined by geometric parameter scanning to realize structure initialization; then electromagnetic The parameter scanning optimization provides a processable sample reference; then, on the basis of the determined geometric parameters and electromagnetic parameters, a reconfigurable elastic wave absorber based on metal nanowire aerogels is sequentially prepared by process means.

The prepared reconfigurable elastic wave absorber based on metal nanowire aerogel can be easily realized by mechanical stretching. The three-layer conductive functional layers of the absorber are all made of metal nanowires, which have excellent stretchability, so that the absorber can maintain large-scale stretching as a whole, and can ensure the stability of mechanical deformation to the greatest extent. The wave filter has stable and reconfigurable performance.

Moreover, the embodiment of the present invention utilizes the aerogel porous structure to prepare the metamaterial structural unit. Since the metal nanowire porous aerogel is used, when the electromagnetic wave is incident on the surface of the aerogel, it will form a good impedance match with the voids on the surface of the aerogel, which can greatly enhance the probability of the electromagnetic wave entering the interior of the metamaterial. At the same time, the aerogel also acts as an electromagnetic wave absorber, so that when the electromagnetic wave passes through the inside of the aerogel, the abundant cell wall surface CWS in the aerogel can perform multiple reflection losses on the electromagnetic wave, thereby greatly enhancing the wave absorbing performance of the material. In addition, the abundant pores inside the aerogel also provide space for polymer elastomer filling, enabling the formation of multiphase composites.

In addition, the embodiment of the present invention uses a polymer elastomer to encapsulate the metal nanowire aerogel, which can greatly reduce the erosion of specific chemical substances in the environment, effectively prevent adverse chemical reactions of the metal nanowires, and greatly improve the metal nanowires. Stability of the conductive network of wire aerogels. At the same time, since the internal microporous structure of the metal nanowire aerogel is infiltrated in the polymer elastomer, the stability of the aerogel structure can also be enhanced and its tensile properties can be improved. In addition, the use of polymer elastomers can endow the wave absorber with elastic deformation ability, so that the wave absorber has good conformal ability, and can be easily and conveniently attached to the surface of the equipment requiring electromagnetic protection; at the same time, during the deformation process, the present invention The wave absorber of the embodiment has high mechanical stability and good flexibility, and can be bent, twisted or even stretched arbitrarily, and can meet the requirements of different electromagnetic wave absorption and protection requirements and the requirements of repeated use in a wide frequency band.

It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "Front", "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise" The orientation or positional relationship indicated by etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, with a specific orientation. The orientation configuration and operation are therefore not to be construed as limitations of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a restructural elasticity wave absorber based on metal nano wire aerogel which characterized in that includes from top to bottom:

the metal nanowire back plate comprises a first wave absorbing layer, a second wave absorbing layer and a metal nanowire back plate;

the first wave absorbing layer comprises a first high polymer elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first high polymer elastomer medium layer; the second wave absorbing layer comprises a second high molecular elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second high molecular elastomer medium layer; the first metal nanowire aerogel microstructure array comprises a plurality of first metal nanowire aerogel microstructures which are periodically arranged at equal intervals; the second metal nanowire aerogel microstructure array comprises a plurality of second metal nanowire aerogel microstructures which are periodically arranged at equal intervals; the metal nanowire backboard is obtained by coating a metal nanowire dispersion liquid on the surface of a high-molecular elastomer film.

2. The metal nanowire aerogel-based reconfigurable elastic wave absorber of claim 1, wherein the first polymer elastomer dielectric layer, the second polymer elastomer dielectric layer and the polymer elastomer in the polymer elastomer thin film comprise:

polydimethylsiloxane PDMS, aliphatic aromatic random copolyester Ecoflex, waterborne polyurethane WPU, thermoplastic polyurethane rubber TPU and natural rubber NR.

3. The metal nanowire aerogel-based reconfigurable elastic wave absorber of claim 1, wherein the first metal nanowire aerogel microstructure, the second metal nanowire aerogel microstructure, and the metal nanowires in the metal nanowire dispersion comprise:

gold nanowires, silver nanowires, and copper nanowires.

4. The metallic nanowire aerogel-based reconfigurable elastic wave absorber of claim 1, wherein the first and second metallic nanowire aerogel microstructures are patterned structures of metallic nanowire aerogel.

5. The metal nanowire aerogel-based reconfigurable elastic wave absorber of claim 4, wherein the patterned structure comprises a zigzag structure, an open resonant ring structure and a cross structure.

6. The metal nanowire aerogel-based reconfigurable elastic wave absorber of claim 1 or 2, wherein for the zigzag structure:

the conductivity of each first metal nanowire aerogel microstructure is 0.1-10S/m; wherein the side length of the square on the outer layer of the square-shaped structure is 12-16 mm; the side length of the inner layer square is 6-10 mm; the thickness of the square-shaped structure is 1.6-2.0 mm; the length of the first high-molecular elastomer medium layer is 13-23 mm; the width of the first high-molecular elastomer medium layer is 13-23 mm; the thickness of the first polymer elastomer dielectric layer is 1.5-2 mm;

the conductivity of each second metal nanowire aerogel microstructure is 0.1-10S/m; wherein the side length of the square on the outer layer of the square-shaped structure is 6-10 mm; the side length of the inner layer square is 1-5 mm; the thickness of the square-shaped structure is 1.6-2.0 mm; the length of the second polymer elastomer dielectric layer is 13-23 mm; the width of the second polymer elastomer dielectric layer is 13-23 mm; the thickness of the second polymer elastomer dielectric layer is 1.5-2 mm.

7. The metal nanowire aerogel-based reconfigurable elastic wave absorber of claim 1 or 2, wherein for the open resonant ring structure:

the conductivity of each first metal nanowire aerogel microstructure is 0.1-10S/m; wherein the excircle radius of the open resonant annular structure is 6-8 mm; the radius of the inner circle is 3-5 mm; the length of the opening rectangle is 6-10 mm; the width of the opening rectangle is 2-6 mm; the vertical distance from the center of the circle to the longer side length of the opening rectangle is 5-8 mm; the thickness of the open resonant annular structure is 1.3-1.5 mm; the length of the first polymer elastomer dielectric layer is 13-23 mm; the width of the first polymer elastomer dielectric layer is 13-23 mm; the thickness of the first polymer elastomer dielectric layer is 1.5-2 mm;

the conductivity of each second metal nanowire aerogel microstructure is 0.1-10S/m; wherein the excircle radius of the open resonant annular structure is 3-5 mm; the radius of the inner circle is 0.5-2.5 mm; the length of the opening rectangle is 2-6 mm, the width of the opening rectangle is 2-6 mm, and the vertical distance from the circle center to the longer side length of the opening rectangle is 3-6 mm; the thickness of the open resonant annular structure is 1.3-1.5 mm; the length of the second polymer elastomer dielectric layer is 13-23 mm; the width of the second polymer elastomer dielectric layer is 13-23 mm; the thickness of the second polymer elastomer dielectric layer is 1.5-2 mm.

8. The reconfigurable elastic wave absorber based on the metal nanowire aerogel as claimed in claim 1, wherein the electrical conductivity of the metal nanowire back plate is 10000-20000S/m; the thickness is 0.1-0.3 mm; the concentration range of the coated metal nanowire dispersion liquid is 45mg/ml to 60 mg/ml.

9. The reconfigurable elastic wave absorber based on metal nanowire aerogel according to claim 1 or 2, wherein the application frequency band of the reconfigurable elastic wave absorber based on metal nanowire aerogel comprises:

the X band and the Ku band.

10. A preparation method of a reconfigurable elastic wave absorber based on metal nanowire aerogel is characterized by comprising the following steps:

step 1, acquiring electromagnetic parameters of aerogel materials cast by metal nanowire dispersion liquid with different concentrations within a preset concentration range at preset sampling intervals according to a target waveband, and determining each electromagnetic parameter range; wherein the electromagnetic parameters include conductivity and permittivity;

step 2, carrying out simulation modeling on the reconfigurable elastic wave absorber based on the metal nanowire aerogel, wherein the structure of the reconfigurable elastic wave absorber comprises from top to bottom: the wave absorbing material comprises a first wave absorbing layer, a second wave absorbing layer and a high polymer elastomer film; the first wave absorption layer comprises a first high molecular elastomer medium layer and a first metal nanowire aerogel microstructure array wrapped in the first high molecular elastomer medium layer; the second wave absorbing layer comprises a second high molecular elastomer medium layer and a second metal nanowire aerogel microstructure array wrapped in the second high molecular elastomer medium layer; the first metal nanowire aerogel microstructure array comprises a plurality of first metal nanowire aerogel microstructures which are periodically arranged at equal intervals; the second metal nanowire aerogel microstructure array comprises a plurality of second metal nanowire aerogel microstructures which are periodically arranged at equal intervals; geometric parameter scanning and optimization are carried out on the reconfigurable elastic wave absorber based on the metal nanowire aerogel obtained through simulation modeling, and initial geometric parameters of a model are obtained;

step 3, on the basis of the initial geometric parameters of the model, based on the corresponding electromagnetic parameter range, scanning the electrical parameters of the reconfigurable elastic wave absorber based on the metal nanowire aerogel, and determining the optimal values of all the electromagnetic parameters;

step 4, preparing the corresponding graphical metal nanowire aerogel by adopting a freeze drying process according to the initial geometric parameters of the model and the optimal values of the electromagnetic parameters to obtain a first metal nanowire aerogel microstructure; forming the first metal nanowire microstructure array by using a plurality of first metal nanowire aerogel microstructures which are periodically arranged at equal intervals, and wrapping the first polymer elastomer dielectric layer around the first metal nanowire microstructure array to form the first wave absorption layer;

step 5, adjusting process parameters, and repeating the step 4 to form the second wave-absorbing layer;

step 6, coating a metal nanowire dispersion liquid with a preset concentration on the cured high polymer elastomer film in a suspension manner, and heating and drying to form a metal nanowire backboard;

and 7, sequentially attaching the prepared first wave absorbing layer, the second wave absorbing layer and the metal nanowire back plate from top to bottom to form the reconfigurable elastic wave absorber based on the metal nanowire aerogel.

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