Application of 100% filled one-dimensional metal organic framework material as green electromagnetic shielding material

Abstract

The invention discloses an application of a 100% filled one-dimensional metal organic framework material as a green electromagnetic shielding material. According to the invention, effective electromagnetic interference shielding is successfully realized by using the original MOF for the first time, the 100%-CuMOF-1D can effectively weaken the dependence of a traditional electromagnetic interference shielding material on reflection loss, so that secondary reflection is greatly reduced, the green shielding index is twice of that of a common commercial product, the electromagnetic interference shielding effect within the range of 1-18 GHz is kept above 20 dB, the SET peak value reaches 34.08 dB, and the electromagnetic interference shielding performance is greatly improved. The material has important application prospects in the field of electromagnetic wave absorption.

Description

Technical Field

[0001] The present invention belongs to the field of metal-organic framework compounds, and particularly relates to the application of a 100% filled one-dimensional metal-organic framework material as a green electromagnetic shielding material. Background Art

[0002] With the wide application of 5G communication and terahertz technology, and driven by the rapid development of the Internet of Things, great progress has been made in fields such as electronic devices, portable artificial intelligence tools, long-distance energy transmission, and radar stealth detection. Unfortunately, these advancements have inevitably led to an increase in electromagnetic pollution, which interferes with the operation of precision instruments and poses a continuous risk to human health. In recent years, efforts have been made to develop efficient electromagnetic interference (EMI) shielding materials to mitigate this unnecessary electromagnetic noise, and significant progress has been made in highly conductive materials. With further research, it has been found that although highly conductive materials can achieve extremely excellent shielding effects and effectively prevent target objects from being affected by electromagnetic interference, they also generate strong secondary reflections on the surface (M. Zhang, C. Han, W. Cao, et al, A nano-micro engineering nanofiber for electromagnetic absorber, green shielding and sensor, Nano-Micro Lett. 13 (2021) 27.). These strong reflected waves interfere with and combine with each other, causing serious secondary reflection pollution.

[0003] To solve the problem of secondary reflection, researchers have shifted their focus to materials with moderate conductivity and multiple attenuation mechanisms, such as nanocellulose, aerogels, foams, biomass materials, and metal-organic framework (MOF)-derived composites. To optimize the shielding mechanism and reduce reflection loss, various design strategies have been proposed, especially the functional gene customization strategy. This method classifies material characteristics related to performance as "genes", such as dielectric, magnetic, conductive, and thermal properties, and reveals the relationship between gene combination, arrangement, composition, and electromagnetic properties. It provides a specific framework for designing green, efficient, and multifunctional electromagnetic materials.

[0004] MOFs have significant advantages in this field due to their inherent uniform pore structure, high specific surface area, and diverse topological structures. The unique metal-organic coordination mode in MOFs enables the precise customization and assembly of secondary building units (SBUs) through reticular chemistry reactions, thereby achieving tailored functionalization to meet specific performance criteria (H. Jiang, D. Alezi, M. Eddaoudi, A reticular chemistry guide for the design of periodic solids, Nat. Rev. Mater. 6 (2021) 466–487.). This makes MOFs an ideal platform for gene-editing multifunctional electromagnetic shielding materials. Unfortunately, as-prepared MOFs without any post-treatment have not been directly applied to electromagnetic wave shielding. Although significant progress has been made in customizing MOFs through methods such as annealing, doping, and in-situ growth to improve their performance, complex multi-step post-treatment and high-temperature pyrolysis inevitably damage the MOF framework. In addition, the functional molecules introduced during the doping process may agglomerate, resulting in uneven dispersion or pore blockage, hindering doping at specific sites. Therefore, developing a platform with atomically precise template reactions to incorporate engineered functional elements into MOFs for ordered assembly remains a distant goal. Summary of the Invention

[0005] The present invention provides an application of a 100% filled one-dimensional metal-organic framework material (100%-CuMOF-1D) as a green electromagnetic shielding material.

[0006] The one-dimensional metal-organic framework material described in the present invention is CuMOF-1D, which is a one-dimensional chain structure synthesized by the formation of O---Cu---O coordination bonds between four hydroxyl groups in octahydroxyphthalocyanine[9,10-b]phthalocyanine[9',10':4,5]thieno[2,3-d]thiophene and metal copper ions. The structural formula is

[0007] The one-dimensional metal-organic framework material CuMOF-1D of the present invention is treated as follows: The one-dimensional metal-organic framework material CuMOF-1D is dispersed in a mixed solvent of ethanol and water (EtOH / H2O) with a volume ratio of 1:1 to form a suspension, and then the suspension is treated in an oven at 65-75 °C, then cooled to room temperature, the precipitate is filtered and separated, and washed with deionized water and ethanol respectively, and dried under vacuum.

[0008] Preferably, the high-temperature treatment time is 5 days.

[0009] Preferably, it is washed 3 times with deionized water and ethanol respectively.

[0010] Preferably, the vacuum drying temperature is 100 °C and the vacuum drying is carried out overnight.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] By simply treating the one-dimensional metal-organic framework material CuMOF-1D, the present invention endows it with extremely excellent electromagnetic wave absorption performance, achieving an efficient and green electromagnetic wave absorption effect without adding paraffin and with a filling amount of 100%. For the first time, effective electromagnetic interference shielding is successfully achieved using the original MOF. An EMI shielding effect of more than 20 dB (attenuation rate 99%) is maintained in the range of 1 - 18 GHz, and a peak SET value of 34.08 dB is reached. The green shielding index is 0.83, which is twice the average of 0.41 of current commercial materials. And it exhibits a high absorption loss (SEA) of 29.75 dB and a low reflection loss (SER) of 4.33 dB. The SEA / SET value reaches 87.3%, and the SEA / SER ratio reaches 6.87. As a green electromagnetic shielding material, 100%-CuMOF-1D has important application prospects in the field of electromagnetic wave absorption. Description of the Drawings

[0013] Figure 1 is the X-ray powder diffraction pattern of 100%-CuMOF-1D;

[0014] Figure 2 is the N2 adsorption-desorption isotherm and pore size distribution of 100%-CuMOF-1D at 77 K;

[0015] Figure 3 is the conductivity change diagram of CuMOF-1D with different filling amounts;

[0016] Figure 4 is the electromagnetic wave absorption performance diagram of CuMOF-1D with different filling amounts;

[0017] Figure 5 is the average EMI, SEA, SER composition diagram of CuMOF-1D with different filling amounts;

[0018] Figure 6 is the green shielding index diagram of CuMOF-1D with different filling amounts;

[0019] Figure 7 is the comparison diagram of effective absorption and absorption coefficient of CuMOF-1D with different filling amounts. Detailed Embodiments

[0020] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below through examples and in conjunction with the accompanying drawings. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention. Unless otherwise specified in the context of this application, the professional terms and abbreviations used in this application are widely known to those skilled in the art; unless otherwise indicated as the manufacturer in the following text, all are conventional products that can be obtained through commercial purchase.

[0021] The one-dimensional metal-organic framework material CuMOF-1D described in the present invention was prepared according to the preparation method of 1D Cu-MOF-1 in the reference (Z. Shan, J.-Z. Xiao, M. Wu, et al, Angew. Chem. Int. Ed. 2024, 63, e202401679).

[0022] Example 1

[0023] The preparation of 100%-CuMOF-1D is as follows:

[0024] Disperse CuMOF-1D (80 mg, 0.12 mmol) in 16 mL of EtOH / H2O (v / v = 8.0 mL / 8.0 mL) to form a suspension. Place the screw bottle of the suspension in an oven at 65 - 75 °C for 5 days. After cooling to room temperature, separate the precipitate by filtration and wash it three times with deionized water and ethanol respectively. Collect the product and dry it under vacuum at 100 °C overnight to finally obtain the dark black powder 100%-CuMOF-1D.

[0025] The structure diagram, powder diffraction pattern, specific surface area / pore structure analysis diagram, and conductivity change diagram of the 100%-CuMOF-1D material are as Figures 1 to 3 shown. Figure 1 is the X-ray powder diffraction pattern of 100%-CuMOF-1D, indicating an accurate atomically resolved structure and excellent crystallinity; Figure 2 is the N2 adsorption-desorption isotherm and pore size distribution of 100%-CuMOF-1D at 77 K, indicating a natural pore structure. Figure 3 is the conductivity change diagram of CuMOF-1D with different filling amounts, indicating excellent and tunable conductivity.

[0026] Comparative Example 1

[0027] This comparative example is basically the same as Example 1, except that the filling amount of CuMOF-1D is 85%, specifically:

[0028] First, mix the one-dimensional metal-organic framework material CuMOF-1D and paraffin in a mass ratio of 85:15. Then, disperse CuMOF-1D and paraffin in 16 mL of EtOH / H2O (v / v = 8.0 mL / 8.0 mL) to form a suspension. Place the screw bottle containing the suspension in an oven for 5 days. After cooling to room temperature, separate the precipitate by filtration and wash it three times with deionized water and ethanol respectively. Collect the product and dry it overnight under vacuum at 100 °C to finally obtain the 85%-CuMOF-1D material.

[0029] Comparative Example 2

[0030] This comparative example is basically the same as Comparative Example 1, except that the filling amount of CuMOF-1D is 70%, and the 70%-CuMOF-1D material is prepared.

[0031] Comparative Example 3

[0032] This comparative example is basically the same as Comparative Example 1, except that the filling amount of CuMOF-1D is 50%, and the 50%-CuMOF-1D material is prepared.

[0033] Comparative Example 4

[0034] This comparative example is basically the same as Comparative Example 1, except that the filling amount of CuMOF-1D is 30%, and the 30%-CuMOF-1D material is prepared.

[0035] Comparative Example 5

[0036] This comparative example is basically the same as Comparative Example 1, except that the filling amount of CuMOF-1D is 15%, and the 15%-CuMOF-1D material is prepared.

[0037] Example 2

[0038] Under the transmission-reflection mode of 2 - 18 GHz, measure the electromagnetic parameters of all samples in Example 1 and Comparative Examples 1 - 4 using a vector network analyzer (Agilent PNA N5224A). Press the samples with different filling rates in Example 1 and the comparative examples into standard rings for measuring electromagnetic wave absorption.

[0039] The outer diameter, inner diameter, and thickness of the annular specimen are set to 7.00, 3.04, and 3.00 mm respectively. The dielectric constant of paraffin is relatively low, which means it is almost transparent to EMW. The microwave absorption characteristics of the samples mixed with paraffin can be used to characterize the properties of the materials.

[0040] The four specific electromagnetic parameters obtained by measurement are the real part of the dielectric constant, the imaginary part of the dielectric constant, the real part of the magnetic permeability constant, and the imaginary part of the magnetic permeability constant. By calculating and simulating these four parameters, the fitting values of the electromagnetic wave reflection loss (RL) and absorption thickness are obtained to determine the electromagnetic wave absorption performance of the material.

[0041] The electromagnetic wave absorption performance of CuMOF-1D with different filling amounts is as Figure 4 shown. Comparing CuMOF-1D with different filling amounts, the EMI shielding effectiveness of 100%-CuMOF-1D reaches 34.08 dB and remains above 20 dB in the entire 1-18 GHz frequency range (attenuation rate 99%), meeting the application requirements of most electronic products.

[0042] Example 3

[0043] Test the EMI, SEA, and SER performance of CuMOF-1D materials with different filling amounts to compare the absorption loss and reflection loss of CuMOF-1D materials with different filling amounts.

[0044] The average EMI, SEA, and SER compositions of CuMOF-1D with different filling amounts are as Figure 5 shown. For CuMOF-1D with different filling amounts, the average absorption loss exceeds the reflection loss, especially at high densities. This indicates that the absorption loss dominates the EMI shielding mechanism, which can be attributed to the polarization effect caused by polar groups. It also helps to reduce electromagnetic pollution caused by secondary reflection.

[0045] Example 4

[0046] In the transmission-reflection mode of 2-18 GHz, test the green shielding index (gs) of CuMOF-1D materials with different filling amounts, and evaluate their environmental friendliness through the green shielding index.

[0047] The green shielding indices of CuMOF-1D with different filling amounts are as Figure 6 shown. The gs value of 100%-CuMOF-1D is 0.83, which is twice that of typical commercial products (such as VO2) (0.41), so it meets the standards of green EMI shielding materials.

[0048] Example 5

[0049] Test the effective absorption and absorption coefficient of CuMOF-1D materials with different filling amounts to compare the electromagnetic wave absorption ability of CuMOF-1D materials with different filling amounts and analyze its mechanism.

[0050] The comparison of the effective absorption and absorption coefficient of CuMOF-1D with different filling amounts is as Figure 7As shown. At all filling levels, the transmission coefficient of CuMOF-1D shows a downward trend with the increase in frequency. Under high conductivity conditions, its maximum value decreases rapidly, ranging from 0.32 to 0.001.

[0051] This indicates that the electromagnetic waves incident on the material are mainly absorbed rather than transmitted. Under low conductivity conditions, both the reflection coefficient and the absorption coefficient increase with the increase in frequency. Their maximum and minimum values also increase with the increase in conductivity, indicating that an appropriate conductivity level is required to achieve effective electromagnetic shielding.

[0052] The negative correlation between the reflection coefficient and the absorption coefficient implies a competitive effect between these two components. It is worth noting that with the increase in conductivity, the difference between these two components gradually decreases, indicating that the polarization loss reduces the dependence on the reflection loss.

Claims

1. Application of 100% filled one-dimensional metal-organic framework material as a green electromagnetic shielding material, characterized in that, The one-dimensional metal-organic framework material is CuMOF-1D, and its structural formula is ， The one-dimensional metal-organic framework material CuMOF-1D is treated as follows: The one-dimensional metal-organic framework material CuMOF-1D is dispersed in a mixed solvent of EtOH / H2O with a volume ratio of 1:1 to form a suspension, and then the suspension is treated in an oven at 65-75 °C, then cooled to room temperature, the precipitate is separated by filtration, and washed with deionized water and ethanol respectively, and dried under vacuum.

2. The application according to claim 1, wherein The high-temperature treatment time is 5 days.

3. The application according to claim 1, wherein Wash with deionized water and ethanol 3 times respectively.

4. The application according to claim 1, characterized in that, The vacuum drying temperature is 100 °C, and vacuum drying is carried out overnight.

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