Terahertz shielding device and preparation method and application thereof

Abstract

The invention discloses a terahertz shielding device and a preparation method and application thereof, and belongs to the field of terahertz wave shielding materials. The preparation method comprises the following steps: fully mixing 100-105 parts by mass of hydroxyl silicone oil (PDMS-OH) and 20-25 parts by mass of hydrogen-containing silicone oil (PDMS-H) to obtain a premix, then fully mixing the premix with a Karstedt catalyst and 40-45 parts by mass of vinyl silicone oil (PDMS-Vi) to form a composite medium, and finally placing the composite medium in a mold for foaming and curing to obtain the terahertz shielding device. According to the terahertz shielding device, in the terahertz wave band range of 0.4-1.4 THz, the terahertz wave absorption rate exceeds 99.9%, the absorption shielding effectiveness exceeds 62.7 dB, and the reflection shielding effectiveness is lower than 0.01 dB. The invention has a wide application prospect in the systems of terahertz detection, terahertz communication, terahertz sensing and the like.

Description

Technical Field

[0001] The invention belongs to the field of terahertz wave shielding materials, and in particular relates to a terahertz shield and a preparation method and application thereof. Background Art

[0002] Terahertz waves have shown very important application prospects in biosensing, security imaging, wireless communications, etc. In recent years, terahertz technology has received widespread attention from countries around the world. With the popularization of terahertz electronic devices and the development of communication technology, the problem of electromagnetic radiation has become increasingly prominent. Electromagnetic interference not only affects the normal operation and service life of the equipment, but also poses a threat to human health. Therefore, the research on electromagnetic shielding devices has attracted much attention. It is usually used in the fields of electromagnetic radiation shielding and interference suppression. Metal materials have long been the traditional choice for electromagnetic interference shielding due to their high robustness and conductivity. However, their high density, poor flexibility and corrosion resistance limit their widespread use, especially in extreme environments. It is worth noting that metal materials cannot completely eliminate electronic interference based on reflection as the main shielding mechanism. The reflected electromagnetic waves will still have a certain impact on the environment and cause secondary pollution. With the rapid development of 6G communication technology, both mobile terminals and base stations have generated a large amount of incremental demand for electromagnetic shielding and thermal conductivity products. At the same time, due to the short wavelength and large transmission loss of terahertz waves, it can be said that opportunities and challenges coexist. With the trend of automobile electrification and 6G communication large-scale antenna arrays, traditional electromagnetic shielding can hardly meet the needs of terahertz waves. Therefore, it is necessary to develop shields that can cope with electromagnetic wave interference at high frequencies and high speeds. Terahertz waves have poor penetration and large attenuation, and their coverage will be greatly weakened. 6G communication has very high requirements for the anti-interference ability of signals, and requires a large number of electromagnetic shields. Therefore, terahertz shields with high absorption, low reflection, low cost and good flexibility play a very important role in the application and development of terahertz technology. Summary of the invention

[0003] The purpose of the present invention is to overcome the technical defects existing in the above-mentioned background technology, and to provide a terahertz shield and a preparation method and application thereof.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] In a first aspect, the present invention provides a method for preparing a terahertz shield, comprising fully mixing 100 to 105 parts by mass of hydroxy silicone oil (PDMS-OH) and 20 to 25 parts by mass of hydrogenated silicone oil (PDMS-H) to obtain a premix, then fully mixing the premix with a Karstedt catalyst and 40 to 45 parts by mass of vinyl silicone oil (PDMS-Vi) to form a composite medium, and finally placing the composite medium in a mold for foaming and curing to obtain the terahertz shield.

[0006] Based on the technical solution disclosed in the first aspect above, the present invention can further provide the following preferred solutions, and if there is no conflict, the preferred solutions can be combined with each other.

[0007] As a preferred embodiment of the first aspect, a graphene oxide aqueous solution is also added when preparing the premix, and the mass percentage of graphene oxide in the final composite medium is 0.05% to 0.1%.

[0008] As a preference for the first aspect above, the mass percentage of the graphene oxide in the final composite medium is 0.05%.

[0009] As a preferred embodiment of the first aspect, the concentration of the Karstedt catalyst in the composite medium is 10-100 ppm.

[0010] As a preferred embodiment of the first aspect, when preparing the premix, the materials are fully mixed by centrifugation, the centrifugal speed is 30π~50π rad / s, and the centrifugal mixing time is 5~20 min.

[0011] As a preferred embodiment of the first aspect, when preparing the composite medium, the materials are fully mixed by centrifugation, the centrifugal speed is 300π~500π rad / s, and the centrifugal mixing time is 1~5 min.

[0012] As a preferred embodiment of the first aspect, during the foaming process, the mold containing the composite medium is placed in an environment of 20° C. to 28° C. for foaming, and the foaming time is 10 to 30 minutes.

[0013] As a preferred embodiment of the first aspect above, during the curing process, the mold containing the composite medium is placed in a hot air circulation dryer for drying and curing, and the curing time is 2 to 4 hours.

[0014] In a second aspect, the present invention provides a terahertz shielding device prepared according to the preparation method described in any one of the schemes in the first aspect.

[0015] As a preferred embodiment of the second aspect, the thickness of the terahertz shield is 2-20 mm.

[0016] In a third aspect, the present invention provides an application of the terahertz shielding device described in the second aspect as a protective layer or protective shell to shield a device from terahertz waves.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1) The terahertz shielding device prepared by the present invention has an excellent shielding effect on terahertz. In the 0.4-1.4THz terahertz band, the absorption rate of terahertz waves is as high as 99.9%, the reflectivity is less than 0.01%, the reflection shielding effectiveness is less than 0.01dB, and the maximum absorption shielding effectiveness is as high as 62.7dB or more.

[0019] 2) The terahertz shielding device made of graphene oxide added in the present invention can improve the terahertz shielding effect of the terahertz shielding device. Due to the unique two-dimensional sheet structure of graphene oxide, the van der Waals force and π-π stacking effect between the layered arrangement, graphene oxide forms a conductive network in the composite material. Under the electromagnetic radiation of terahertz waves, the conductive network can migrate in the material through free electrons to form current or electric dipole moment. This process can effectively absorb the energy of terahertz waves and convert it into heat energy, thereby achieving strong absorption of terahertz waves. In addition, conductive electrons can not only absorb the energy of terahertz waves, but also scatter part of the electromagnetic waves through the scattering mechanism. Finally, the existence of the porous structure of the medium of the terahertz shielding device will cause the scattered electromagnetic waves to undergo multiple scatterings, resulting in energy loss and enhancing the absorption of the material. Graphene oxide will produce a thermal effect when absorbing electromagnetic waves, and the methyl foam structure formed by the remaining components can effectively spread and disperse heat, thereby avoiding local overheating and maintaining the stability of the material.

[0020] 3) The material of the terahertz shield prepared by the present invention also has certain flame retardancy, and can effectively hinder the combustion rate of the composite medium under extreme conditions such as fire and ultra-high temperature.

[0021] 4) The terahertz shielding device prepared by the present invention has the advantages of simple manufacturing process, low manufacturing cost, high shielding effectiveness and excellent flame retardancy. At the same time, the terahertz shielding operation can be performed in a wide temperature range of -100°C to 300°C, showing the potential application value under extreme conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 are optical photographs of three terahertz shielding device samples in the embodiments of the present invention, (a) is the terahertz shielding device sample prepared in embodiment 1, (b) is the terahertz shielding device sample prepared in embodiment 2, and (c) is the terahertz shielding device sample prepared in embodiment 3;

[0023] Figure 2 is the terahertz time domain spectrum of the terahertz shield prepared in Examples 1 to 3;

[0024] Figure 3 is the terahertz frequency domain spectrum of the terahertz shield prepared in Examples 1 to 3;

[0025] Figure 4is the terahertz absorption coefficient curve of the terahertz shield prepared in Examples 1 to 3;

[0026] Figure 5 is a terahertz absorption and shielding effectiveness diagram of the terahertz shielding device prepared in Examples 1 to 3;

[0027] Figure 6 is a terahertz reflection shielding effectiveness diagram of the terahertz shielding device prepared in Examples 1 to 3;

[0028] Figure 7 3 is a diagram of the terahertz total shielding effectiveness of the terahertz shielding devices prepared in Examples 1 to 3. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0030] The present invention adopts three kinds of silicone oil, graphene oxide (GO) and Karstedt catalyst to prepare terahertz shielding device, wherein graphene oxide is an optional component. The three kinds of silicone oil are hydroxy silicone oil (PDMS-OH), hydrogen silicone oil (PDMS-H) and vinyl silicone oil (PDMS-Vi).

[0031] The molecular formula of hydroxy silicone oil (PDMS-OH) is as follows:

[0032]

[0033] The molecular formula of hydrogenated silicone oil (PDMS-H) is as follows:

[0034]

[0035] The molecular formula of vinyl silicone oil (PDMS-Vi) is as follows:

[0036]

[0037] The three silicone oils, graphene oxide (GO) and Karstedt's catalyst are all existing commercially available materials, and commercial reagents can be used.

[0038] In a preferred embodiment of the present invention, a method for preparing a terahertz shield is provided, and the specific method is: 100-105 parts by mass of hydroxy silicone oil (PDMS-OH) and 20-25 parts by mass of hydrogen-containing silicone oil (PDMS-H) are fully mixed to obtain a premix, and then the premix is ​​fully mixed with a Karstedt catalyst and 40-45 parts by mass of vinyl silicone oil (PDMS-Vi) to form a composite medium, and finally the composite medium is placed in a mold for foaming and curing to obtain a terahertz shield.

[0039] In another embodiment of the present invention, another method for preparing a terahertz shielding device introducing graphene oxide is provided, and the specific method is as follows:

[0040] 100-105 parts by mass of hydroxy silicone oil (PDMS-OH), 20-25 parts by mass of hydrogenated silicone oil (PDMS-H) and graphene oxide aqueous solution are fully mixed to obtain a premix, and then the premix is ​​fully mixed with Karstedt catalyst and 40-45 parts by mass of vinyl silicone oil (PDMS-Vi) to form a composite medium, and finally the composite medium is placed in a mold for foaming and curing to obtain a terahertz shield.

[0041] In the above two schemes, terahertz shielding devices can be prepared with or without the introduction of graphene oxide. In general, when graphene oxide is not introduced, the final terahertz shielding device is composed of pure methyl foam; while after the introduction of graphene oxide, the prepared terahertz shielding device is a composite of methyl foam and graphene oxide, which has better performance for terahertz shielding.

[0042] In the above two schemes of the present invention, the specific materials and parameters in the preparation process are preferably as follows:

[0043] For the added Karstedt catalyst, the concentration of the Karstedt catalyst in the composite medium is 10~100ppm. When preparing the above-mentioned premix, the materials can be fully mixed by centrifugation, the centrifugal speed is 30π~50πrad / s, and the centrifugal mixing time is 5~20 min. When preparing the composite medium, the materials can also be fully mixed by centrifugation, the centrifugal speed is 300π~500π rad / s, and the centrifugal mixing time is 1~5 min. During the foaming process, the mold containing the composite medium can be placed in an environment of 20℃~28℃ for foaming, and the foaming time is 10~30min. During the curing process, the mold containing the composite medium can be placed in a hot air circulation dryer for drying and curing, and the curing time is 2~4 h.

[0044] Further preferably, the concentration of the Karstedt catalyst in the composite medium is preferably 10 to 20 ppm. When preparing the above premix, the centrifuge is stirred at a speed of 34πrad / s for 10 minutes, and when preparing the composite medium, the centrifuge is stirred at a speed of 400πrad / s for 1 minute. During the foaming process, the mold containing the composite medium can be placed in an environment of 23°C for 20 minutes of foaming. During the curing process, the mold is placed in a hot air circulation dryer for 3.5 hours of drying and curing.

[0045] It should be noted that, during the preparation process of foaming and curing, the terahertz shield can be made into different shapes according to the requirements of the use scenario, for example, it can be a layer or a shell, which can be realized by designing a corresponding mold. The terahertz shield prepared by the present invention can be used as a protective layer or protective shell to shield the device from terahertz waves.

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments.

[0047] Example 1

[0048] A lightweight and efficient terahertz shield of pure methyl foam was prepared according to the following steps:

[0049] Take 500g of hydroxy silicone oil (PDMS-OH) and 100g of hydrogen silicone oil (PDMS-H), mix them preliminarily, and stir them at 34πrad / s for 10min in a centrifuge to form a premix. Then, preliminarily mix 200g of vinyl silicone oil (PDMS-Vi) and 0.015g of Karstedt catalyst with the premix, stir them at 40πrad / s for 1min in a centrifuge to fully mix and obtain a composite medium. Place the composite medium in a mold for foaming at room temperature 23°C and for 20min. After foaming, transfer it to a hot air circulation dryer and dry it for 3.5h to complete the preparation of the terahertz shield.

[0050] In this embodiment, the mass ratio of hydroxy silicone oil (PDMS-OH), hydrogen silicone oil (PDMS-H) and vinyl silicone oil (PDMS-Vi) is 100:20:40, and the Karstedt catalyst accounts for 10-20ppm of the total mass of the composite medium. The terahertz shielding device sample finally prepared is a layer with a thickness of 10mm. The optical photo of the sample is shown in FIG. Figure 1 As shown in part (a) of .

[0051] Example 2

[0052] A lightweight and efficient terahertz shielding device of methyl foam plus 0.05% graphene oxide was prepared according to the following steps:

[0053] Take 500g of hydroxy silicone oil (PDMS-OH), 100g of hydrogenated silicone oil (PDMS-H) and 22g of 1.9wt% graphene oxide aqueous solution, mix them preliminarily, and stir them at 34πrad / s for 10min using a centrifuge to form a premix. Then, preliminarily mix 200g of vinyl silicone oil (PDMS-Vi) and 0.015g of Karstedt catalyst with the premix, stir them at 40πrad / s for 1min using a centrifuge to fully mix and obtain a composite medium. The composite medium is placed in a mold for foaming at a room temperature of 23°C and a foaming time of 20min. After foaming, transfer it to a hot air circulation dryer and dry it for 3.5h to complete the preparation of the terahertz shield.

[0054] In this embodiment, the mass ratio of hydroxy silicone oil (PDMS-OH), hydrogen silicone oil (PDMS-H) and vinyl silicone oil (PDMS-Vi) is 100:20:40, graphene oxide accounts for 0.05% of the total mass of the composite medium, and Karstedt catalyst accounts for 10-20ppm of the total mass of the composite medium. The terahertz shielding sample finally prepared is a layer with a thickness of 10mm. The optical photo of the sample is shown in FIG. Figure 1 As shown in part (b) of .

[0055] Example 3

[0056] A lightweight and efficient terahertz shielding device of methyl foam plus 0.1% graphene oxide was prepared according to the following steps:

[0057] Take 500g of hydroxy silicone oil (PDMS-OH), 100g of hydrogenated silicone oil (PDMS-H) and 45g of 1.9wt% graphene oxide aqueous solution, mix them preliminarily, and stir them at 34πrad / s for 10min using a centrifuge to form a premix. Then, preliminarily mix 200g of vinyl silicone oil (PDMS-Vi) and 0.015g of Karstedt catalyst with the premix, stir them at 40πrad / s for 1min using a centrifuge to fully mix and obtain a composite medium. Place the composite medium in a mold for foaming, the foaming temperature is room temperature 23°C, and the foaming time is 20min. After foaming, transfer it to a hot air circulation dryer and dry it for 3.5h to complete the preparation of the terahertz shield.

[0058] In this embodiment, the mass ratio of hydroxy silicone oil (PDMS-OH), hydrogen silicone oil (PDMS-H) and vinyl silicone oil (PDMS-Vi) is 100:20:40, graphene oxide accounts for 0.1% of the total mass of the composite medium, and Karstedt catalyst accounts for 10-20ppm of the total mass of the composite medium. The terahertz shielding device sample finally prepared is a layer with a thickness of 10mm. The optical photo of the sample is shown in FIG. Figure 1 As shown in part (c) of .

[0059] Based on the lightweight and efficient terahertz shielding device of pure methyl foam prepared in the above Example 1, the lightweight and efficient terahertz shielding device of methyl foam plus 0.05% graphene oxide prepared in the above Example 2, and the lightweight and efficient terahertz shielding device of methyl foam plus 0.1% graphene oxide prepared in the above Example 3, terahertz wave reflection and transmission spectrum experimental tests were carried out on the three lightweight and efficient terahertz shielding device samples using a terahertz time-domain spectroscopy detection system. The working principle of the terahertz wave time-domain spectrum system is as follows: the titanium sapphire femtosecond mode-locked pulse laser generates a laser light source with a central wavelength of 800nm, a repetition frequency of 80MHz, and a pulse width of 100, and the output power is 960mW. The light beam is divided into a strong pump light and a weak detection light by a beam splitter. The pump light is modulated by a chopper and focused by a lens to emit to the photoconductive antenna gallium arsenide (GaAs) crystal to excite the terahertz pulse. The terahertz pulse is collimated and incident on the sample through two off-axis metal parabolic mirrors, and then focused by another two metal parabolic mirrors to reach the 2mm thick zinc telluride ZnTe crystal, and merges with the detection light through the delay line. At this time, the electric field of the terahertz electromagnetic radiation pulse modulates the refractive index ellipsoid of the electro-optical crystal ZnTe through the linear electro-optic effect, and the polarization state of the detection light changes accordingly, which is detected by a balanced diode, and the signal is sent to the phase-locked amplifier for amplification, and the entire time domain waveform of the terahertz signal is detected by changing the length of the delay line. In order to avoid the influence of water vapor in the air on the experimental results, the terahertz transmitter, receiver and tested samples were placed in a sealed cover filled with nitrogen. The temperature in the cover was 21 °C and the air humidity was about 5%.

[0060] The terahertz time domain waveforms of three lightweight and efficient terahertz shields are shown in Figure 2. Figure 2 As shown in Figure 1, the terahertz wave time domain spectra of different graphene oxide contents have different performances, and the time domain peaks have certain differences. The corresponding terahertz wave frequency domain spectrum can be obtained by Fourier transforming the time domain spectrum, as shown in Figure 1. Figure 3 shown. Figure 4 The terahertz wave absorption coefficients of three lightweight and efficient terahertz shields. The graphene oxide content has a certain influence on the terahertz wave absorption coefficient. Figure 5 The terahertz absorption and shielding effectiveness of three lightweight and efficient terahertz shielding devices. It can be seen that the higher the graphene oxide content, the stronger the absorption and shielding effectiveness of the terahertz shielding device. When the graphene oxide content is 0.1%, the terahertz absorption and shielding effectiveness of the terahertz shielding device can reach 62.7dB. Figure 6 The terahertz reflection shielding effectiveness of three lightweight and efficient terahertz shields. It can be seen from the figure that the reflection shielding effectiveness of the three composite media is less than 0.01dB. Figure 7This is the total terahertz shielding effectiveness of three lightweight and efficient terahertz shields, and the absorption shielding effectiveness accounts for more than 99.9% of the total shielding effectiveness.

[0061] In summary, the lightweight and efficient terahertz shielding device prepared by the present invention uses the absorption of terahertz waves as the main shielding mechanism, has a low terahertz wave reflectivity, and acts as a protective layer or protective shell to shield the device from terahertz waves, preventing terahertz waves from re-entering the environment and causing secondary pollution, and has broad application prospects. The terahertz shielding devices prepared by the above three embodiments can basically eliminate terahertz waves, and can maintain the terahertz shielding effect in a wide temperature range of -100°C to 300°C, showing potential application value under extreme conditions.

[0062] However, the above detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but only represents some of the best embodiments of the present invention. Based on the embodiments of the present invention, various parameter ranges can be adjusted accordingly. Through relevant gradient tests, theoretically, 100 to 105 parts by mass of hydroxy silicone oil (PDMS-OH), 20 to 25 parts by mass of hydrogenated silicone oil (PDMS-H), and graphene oxide aqueous solution (accounting for 0.05 wt.% to 0.1 wt.% of the mass percentage of the composite medium) are fully mixed to obtain a premix, and then the premix is ​​fully mixed with Karstedt catalyst (the concentration in the composite medium is 10 to 100 ppm) and 40 to 45 parts by mass of vinyl silicone oil (PDMS-Vi) to form a composite medium, and finally the composite medium is placed in a mold for foaming and curing, and a terahertz shield can be obtained, with only differences in shielding performance.

[0063] Therefore, those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A method for preparing a terahertz shield, characterized in that: 100-105 parts by mass of hydroxy silicone oil and 20-25 parts by mass of hydrogenated silicone oil are fully mixed to obtain a premix, and then the premix is ​​fully mixed with a Karstedt catalyst and 40-45 parts by mass of vinyl silicone oil to form a composite medium, and finally the composite medium is placed in a mold for foaming and curing to obtain a terahertz shield.

2. The method for preparing the terahertz shield according to claim 1, characterized in that: When preparing the premix, a graphene oxide aqueous solution is also added, and the mass percentage of graphene oxide in the final composite medium is 0.05% to 0.1%.

3. The method for preparing the terahertz shield according to claim 1 or 2, characterized in that: The concentration of the Karstedt catalyst in the composite medium is 10-100 ppm.

4. The method for preparing the terahertz shield according to claim 1 or 2, characterized in that: When preparing the premix, the materials are fully mixed by centrifugation, the centrifugal speed is 30π~50π rad / s, and the centrifugal mixing time is 5~20min.

5. The method for preparing the terahertz shield according to claim 1 or 2, characterized in that: When preparing the composite medium, the materials are fully mixed by centrifugation, the centrifugal speed is 300π~500π rad / s, and the centrifugal mixing time is 1~5 min.

6. The method for preparing the terahertz shield according to claim 1 or 2, characterized in that: During the foaming process, the mold containing the composite medium is placed in an environment of 20°C to 28°C for foaming, and the foaming time is 10 to 30 minutes.

7. The method for preparing the terahertz shield according to claim 1 or 2, characterized in that: During the curing process, the mold containing the composite medium is placed in a hot air circulation dryer for drying and curing, and the curing time is 2 to 4 hours.

8. A terahertz shield prepared according to the preparation method of claim 1 or 2.

9. The terahertz shield according to claim 8, characterized in that: The thickness of the terahertz shield is 2-20 mm.

10. Use of the terahertz shielding device as claimed in claim 8 as a protective layer or protective shell to shield terahertz waves of equipment.

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