Composite nanofiber membrane sound absorption material and preparation method thereof

Abstract

The invention relates to the technical field of novel composite nanofiber membrane sound absorption materials, and discloses a composite nanofiber membrane sound absorption material and a preparation method thereof.The preparation method comprises the steps that a metal organic framework material ZIF-8 and a ferroelectric polymer PVDF-TrFE are dispersed in a solvent to obtain a spinning solution, and the spinning solution is subjected to electrostatic spinning to obtain a ZIF-8-coated PVDF-TrFE nanofiber membrane. According to the scheme, the ZIF-8 and the PVDF-TrFE are mixed to be used for preparing the ZIF-8-coated PVDF-TrFE nanofiber membrane, and the ZIF-8 has a unique pore channel structure and a large specific surface area, so that scattering and absorption of the material to sound waves can be improved; pVDF-TrFE has good ferroelectric performance and can cooperate with ZIF-8, the overall sound absorption effect of the material is improved, and the sound absorption lower limit of the material in a low-frequency band is effectively reduced. The sound absorption lower limit corresponding to the sound absorption coefficient 0.5 of the ZIF-8-coated PVDF-TrFE nanofiber membrane in the scheme is as low as 215 Hz, and low-frequency noise interference is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of novel composite nanofiber membrane sound-absorbing materials, and particularly relates to a composite nanofiber membrane sound-absorbing material and a preparation method thereof. Background Art

[0002] In the current booming development of modern industry and transportation, noise pollution has become a severe environmental problem. Due to the special physical properties of low-frequency noise, such as long wavelength, long propagation distance, strong penetration ability, and the poor absorption effect of traditional sound-absorbing materials on it, it brings great troubles to people's lives and health. Among many sound-absorbing materials, traditional sound-absorbing foams have problems such as a relatively high sound absorption lower limit and unsatisfactory low-frequency sound absorption effect; micro-perforated plates also have limitations in low-frequency sound absorption and are difficult to meet the requirements for efficient control of low-frequency noise.

[0003] In the prior art, there have also been many studies and attempts on composite nanofiber membrane sound-absorbing materials. For example, the patent with the publication number CN119287535A, a preparation method and device for flash-sprayed nanofibers, uses flash evaporation and melt blowing methods to produce nanofibers of different thicknesses. By adjusting the proportion of nanofibers of different thicknesses in the mixing cylinder, the acoustic performance adjustment for specific frequency bands can be achieved. However, this method mainly focuses on the adjustment of the fiber thickness ratio for specific frequency bands and has deficiencies in improving comprehensive performances such as achieving a lower sound absorption lower limit, an ultra-thin film thickness, a higher low-frequency average sound absorption coefficient, and a wider low-frequency sound absorption bandwidth, and it is difficult to meet the requirements for comprehensive and efficient control of low-frequency noise within a compact size range.

[0004] Another example is that some studies prepare a three-layer fiber sponge including an "ultrafine fiber layer - micro / nanofiber layer - nanofiber layer" through multi-layer electrospinning. The gradient change of its porosity and pore size endows the fiber sponge material with efficient absorption of broadband sound waves. However, this material not only has an insufficiently low sound absorption lower limit in the low-frequency band but also has a relatively thick thickness, and it is difficult to achieve an extremely thin film thickness, and it cannot meet the application scenarios with strict requirements for space and weight in aerospace, electronic products, etc.

[0005] There is also a method of compounding nanofibers with thin-film acoustic metamaterials. The micro-nano gradient fiber layer has a gradient porous structure and can absorb sound energy; the thin-film acoustic metamaterials have special acoustic properties and can achieve sound absorption and sound insulation effects such as negative refraction. However, the low-frequency average sound absorption coefficient of this composite structure still needs to be improved, and it cannot efficiently absorb low-frequency noise, and it is difficult to create a quieter and more comfortable acoustic environment.

[0006] Therefore, developing a novel composite nanofiber membrane sound-absorbing material with a wider low-frequency sound absorption bandwidth not only effectively makes up for the deficiencies of the prior art but also can be used for low-frequency noise control within a compact size range, which is of great significance for low-frequency noise control. Summary of the Invention

[0007] The present invention aims to provide a composite nanofiber membrane sound-absorbing material and a preparation method thereof, so as to solve the technical problem that the existing nanofiber membrane sound-absorbing material has an insufficiently low sound absorption lower limit in the low-frequency band.

[0008] To achieve the above object, the present invention adopts the following technical solution: A composite nanofiber membrane sound-absorbing material, comprising obtaining a ZIF-8 dispersion liquid by dispersing a metal-organic framework material ZIF-8 in acetone; then dispersing a ferroelectric polymer PVDF-TrFE in a solvent DMF to obtain a PVDF-TrFE solution, and subsequently dropping the ZIF-8 dispersion liquid into the PVDF-TrFE solution to obtain a spinning solution, and the spinning solution is subjected to electrospinning to obtain a ZIF-8@PVDF-TrFE nanofiber membrane.

[0009] Principle and advantages of this solution:

[0010] 1. Compared with the existing sound-absorbing material obtained by compounding multiple layers of fibers, whose sound absorption lower limit in the low-frequency band is still not low enough, in this solution, ZIF-8 (Zeolitic Imidazolate Framework-8, a kind of metal-organic framework material MOFs) and PVDF-TrFE (polyvinylidene fluoride-trifluoroethylene copolymer) are mixed to prepare a ZIF-8@PVDF-TrFE nanofiber membrane. ZIF-8 has a unique pore structure and a large specific surface area, which can increase the scattering and absorption of sound waves by the material; while PVDF-TrFE has good ferroelectric properties and can cooperate with ZIF-8 to enhance the overall sound absorption effect of the material and effectively reduce its sound absorption lower limit in the low-frequency band. Specifically, the nanofiber membrane prepared by electrospinning in this solution not only has a porous sound absorption structure but also can form a resonance sound absorption mechanism. When the frequency of the incident sound wave is consistent with the frequency of the material itself, a resonance phenomenon will occur, causing the conversion of sound energy form. This mechanism makes up for the defect that the porous sound absorption material has poor sound absorption effect in the mid-low frequency band. And the sound wave entering the material can be converted into other forms of energy and attenuated while being dissipated in the form of heat energy, such as electrical energy. The piezoelectric material polyvinylidene fluoride (PVDF) can realize the conversion of sound energy into electrical energy form, making the material have a good absorption effect on sound waves in the low-frequency region. The sound absorption lower limit corresponding to the sound absorption coefficient of 0.5 of the ZIF-8@PVDF-TrFE nanofiber membrane in this solution is as low as 215 Hz, effectively reducing low-frequency noise interference.

[0011] 2. In this solution, by mixing ZIF-8 and PVDF-TrFE to prepare a spinning solution and then electrospinning to form a nanofiber membrane, not only the uniformity of the distribution of ZIF-8 in the nanofiber membrane is effectively improved, but also the continuity of the electrospinning process of the nanofiber membrane is enhanced, avoiding breakage during the electrospinning process and affecting the electrospinning efficiency.

[0012] 3. By optimizing the mass ratio of the two raw materials in the ZIF-8@PVDF-TrFE nanofiber membrane, it is convenient to control the consistency of the spinning solution. While effectively reducing the thickness of the finished nanofiber membrane, it ensures that it has a higher low-frequency average sound absorption coefficient, improves the sound absorption performance, and thus facilitates its application in various fields.

[0013] Preferably, as an improvement, the concentration of PVDF-TrFE in the spinning solution is 12-16 wt%, and the concentration of ZIF-8 in the spinning solution is 0.4-1.67 wt% of the PVDF-TrFE concentration.

[0014] Beneficial effects: With the above settings in this solution, it is convenient to achieve the optimal ratio of ZIF-8 and PVDF-TrFE in the dispersion liquid, thereby improving the sound absorption performance of the composite nanofiber membrane. Specifically, appropriate concentrations can ensure the uniform dispersion of the two materials and give full play to their respective characteristics, synergistically enhancing the sound absorption effect. Through long-term experiments, the applicant found that if the concentration of ZIF-8 is too high, the structure of the fiber membrane will be uneven due to severe agglomeration, affecting the sound absorption performance; if the concentration of PVDF-TrFE is too high or too low, the overall sound absorption performance of the material will decrease due to the inability to form a good synergistic effect with ZIF-8.

[0015] Preferably, as an improvement, the composition of PVDF-TrFE is 70 / 30 mole percentage.

[0016] Beneficial effects: With the above settings in this solution, it is convenient to improve the performance of the prepared nanofiber membrane. Specifically, the composition ratio of 70 / 30 can significantly enhance the piezoelectric performance of PVDF-TrFE, making it perform better in applications such as sensors and actuators. In addition, this ratio helps to form a nanofiber membrane with appropriate crystallinity, ensuring that the material has good mechanical strength and flexibility. Through long-term experiments, the applicant found that if the proportion of PVDF is too high, the material will become brittle due to too high crystallinity, resulting in a decrease in flexibility and an increase in processing difficulty; it will also reduce the piezoelectric response and lead to a decrease in piezoelectric performance. If the proportion of PVDF is too low, the material will be too soft due to insufficient mechanical properties and difficult to maintain its shape. If the proportion of TrFE is too high, the material will have insufficient mechanical strength due to too low crystallinity and be prone to deformation; it will also be prone to degradation at high temperatures due to poor thermal stability, limiting its application range. If the proportion of TrFE is too low, the piezoelectric characteristics of the copolymer cannot be fully exerted due to the decrease in piezoelectric performance.

[0017] Preferably, as an improvement, the thickness of the ZIF-8@PVDF-TrFE nanofiber membrane is 0.25-0.75 mm.

[0018] Beneficial effects: With the above settings, this solution facilitates the thinning of the material while ensuring sound absorption performance. Specifically, an appropriate film thickness can maintain a good sound absorption effect while meeting the application requirements of compact spaces, making the material applicable in more scenarios. Through long-term experiments, the applicant found that factors such as the diameter and morphology of the fibers, the areal density, porosity, and thickness of the material all affect the sound absorption performance of the nanofiber material. Specifically, the finer the fibers, the more fiber roots per unit mass, increasing the probability of interaction between sound waves and fibers; at the same time, finer fibers are more likely to deform due to the vibration of sound waves, causing the pore channels inside the fibers to become more tortuous, thereby increasing the air flow resistance and improving the sound absorption performance of the material. If the film thickness is less than 0.25 mm, the path for sound waves to propagate and be absorbed in the material will be insufficient due to the overly thin thickness, resulting in a significant decline in sound absorption performance; if the film thickness is greater than 0.75 mm, it will increase the weight and volume of the material, making it unsuitable for application scenarios with strict requirements for space and weight.

[0019] Preferably, as an improvement, the average sound absorption coefficient of the ZIF-8@PVDF-TrFE nanofiber membrane in the frequency range of 50 - 1000 Hz is 0.58 - 0.63.

[0020] Beneficial effects: With the above settings, this solution facilitates the effective absorption of low-frequency noise and improves the acoustic environment. Specifically, having a high average sound absorption coefficient in the key low-frequency range of 50 - 1000 Hz can significantly reduce the interference of low-frequency noise on people's lives and work. Through long-term experiments, the applicant found that if the average sound absorption coefficient is lower than 0.58, the insufficient sound absorption ability will result in the inability to effectively reduce low-frequency noise in actual applications, making it difficult to achieve an ideal acoustic effect.

[0021] Preferably, as an improvement, this solution also provides a preparation method for a composite nanofiber membrane sound absorption material, including the following steps:

[0022] Step 1: Prepare ZIF-8: Disperse zinc nitrate and 2-methylimidazole in methanol solutions respectively, denoted as solution A and solution B, and ultrasonically dissolve them completely at room temperature; under stirring, dropwise add solution B into solution A, continue stirring for 60 min after complete addition, and then let it stand at room temperature for 20 - 24 h to obtain a mixed solution; the mixed solution is subjected to centrifugation, methanol washing, drying, and grinding treatments to obtain nano-ZIF-8 powder;

[0023] Step 2: Prepare a ZIF-8 dispersion: Disperse the nano-ZIF-8 powder in acetone, and then add PA and PFOES, and ultrasonically mix them evenly at room temperature to obtain a ZIF-8 dispersion;

[0024] Step 3. Prepare the spinning solution: Disperse PVDF-TrFE powder in DMF solution to obtain a ZIF-8 dispersion; then disperse the ferroelectric polymer PVDF-TrFE in the solvent DMF to obtain a PVDF-TrFE solution, and then drop the ZIF-8 dispersion into the PVDF-TrFE solution to obtain the spinning solution;

[0025] Step 4. Electrospinning: The spinning solution is electrospun by an electrospinning machine to obtain ZIF-8@PVDF-TrFE nanofibers.

[0026] Beneficial effects: With the above settings in this solution, it is convenient to prepare ZIF-8@PVDF-TrFE nanofiber membranes with excellent sound absorption performance. Specifically, when preparing ZIF-8 in Step 1, it is specified to dropwise add a methanol solution of 2-methylimidazole under stirring, which can make the reaction proceed slowly and evenly, contribute to controlling the growth of ZIF-8 crystals, and thus obtain products with relatively consistent particle sizes; continuing to stir for 6 h and standing for 12 - 16 h after complete addition can ensure the full completion of the reaction and convert the reactants into ZIF-8 as much as possible. When preparing the ZIF-8 dispersion in Step 2, adding PA (n-propylamine, CH 3 CH 2 CH 2 NH 2 ) and PFOES (tridecafluorooctyltriethoxysilane, C 14 H 19 F 13 O 3 Si) can act as a dispersant and stabilizer, reducing the agglomeration between ZIF-8 particles. Ultrasonically mixing evenly at room temperature, the cavitation effect of ultrasound can further break the agglomeration of ZIF-8 particles, making ZIF-8 reach a more uniform dispersion state in acetone, thereby ensuring the stability of the dispersion. When preparing the spinning solution in Step 3, dispersing PVDF-TrFE powder in DMF solution (N,N-dimethylformamide solution), DMF can dissolve PVDF-TrFE well, forming a homogeneous solution. After mixing with the ZIF-8 dispersion, magnetic stirring treatment is carried out. Magnetic stirring can make the two solutions mix fully, and under heating conditions, it can accelerate the dissolution rate of PVDF-TrFE and promote the interaction between components, making it fully dissolve and evenly distribute. Standing at room temperature can allow the bubbles in the solution to naturally escape, avoiding defects such as fiber breakage and voids caused by the presence of bubbles in the subsequent electrospinning process. In Step 4, through electrospinning, the diameter, morphology, and arrangement of the fibers can be precisely controlled, thereby preparing ZIF-8@PVDF-TrFE nanofibers with good sound absorption performance.

[0027] Preferably, as an improvement, in Step 1, the molar ratio of 2-methylimidazole to Zn in the mixed solution is 3 - 5:1.

[0028] Beneficial effects: With the above settings, this solution facilitates the control of the generation of ZIF-8 and obtains nano-ZIF-8 powder with stable performance. Specifically, appropriate concentration and volume ratio can enable zinc nitrate and 2-methylimidazole to react fully, generating ZIF-8 with ideal structure and performance. Through long-term experiments, the applicant found that if the concentration of zinc nitrate or 2-methylimidazole is too high or too low, or the mixing volume ratio is inappropriate, the particle size, purity, and structure of ZIF-8 will change due to the change of reaction conditions, thereby affecting the sound absorption performance of the final composite nanofiber membrane.

[0029] Preferably, as an improvement, in step one, the stirring speed is 250 - 500 rpm, and the centrifugation treatment is centrifugation at 4500 - 8000 rpm for 5 - 10 min.

[0030] Beneficial effects: With the above settings, this solution facilitates ensuring the full progress of the reaction and effectively separating the ZIF-8 product. Specifically, an appropriate stirring speed can fully mix the reactants and promote the reaction; appropriate centrifugation speed and time can effectively separate the generated ZIF-8 from the solution. Through long-term experiments, the applicant found that if the stirring speed is too fast or too slow, the reaction will be incomplete or the particle size of the generated ZIF-8 will be uneven due to uneven mixing of the reactants; if the centrifugation speed is too low or the time is too short, impurities will remain due to incomplete separation, affecting the quality of ZIF-8.

[0031] Preferably, as an improvement, in step two, the addition amounts of PA and PFOE are 4 - 5 wt% and 1 - 2 wt% of the nano-ZIF-8 powder respectively; the ultrasonic mixing time is 30 - 45 min.

[0032] Beneficial effects: With the above settings, this solution facilitates improving the dispersion stability of ZIF-8 in the dispersion liquid. Specifically, appropriate amounts of PA and PFOE can reduce the agglomeration between ZIF-8 particles, enabling them to be evenly dispersed in acetone, which is beneficial for subsequent preparation of the spinning solution and improving the performance of the fiber membrane. The ultrasonic effect can further disperse the ZIF-8 particles, break the agglomeration, and make the dispersion liquid more stable. Through long-term experiments, the applicant found that if the addition amount of PA or PFOE is too small, ZIF-8 will agglomerate due to the inability to effectively reduce the interaction between particles, affecting the uniformity of the fiber membrane; if the addition amount is too large, too many impurities will be introduced, affecting the sound absorption performance of the fiber membrane. If the ultrasonic mixing time is too short, ZIF-8 will be unevenly dispersed due to insufficient mixing, affecting subsequent spinning and the performance of the fiber membrane; if the ultrasonic time is too long, the structure of ZIF-8 may be damaged, reducing its performance.

[0033] Preferably, as an improvement, in step three, the magnetic stirring treatment is to heat and mix for 6 - 8 h at a temperature of 80 - 85°C and a rotation speed of 400 - 500 r / min; the room temperature standing time is 12 - 16 h.

[0034] Beneficial effects: With the above settings in this solution, it is convenient for the full and uniform mixing of PVDF-TrFE, DMF solution, and ZIF-8 dispersion. Standing at room temperature facilitates the full discharge of air bubbles in the solution, preventing them from reducing the uniformity and continuity of the fibers obtained by electrospinning. Specifically, heating and stirring at appropriate temperature and rotation speed can fully dissolve PVDF-TrFE and uniformly mix it with the ZIF-8 dispersion; sufficient standing time allows the air bubbles in the solution to naturally discharge. Through long-term experiments, the applicant found that if the heating temperature is too high or the stirring time is too long, the material may degrade; if the standing time is too short, defects such as fiber breakage and holes may occur during electrospinning due to the remaining air bubbles, affecting the quality of the sound-absorbing material.

[0035] Preferably, as an improvement, in step four, during electrospinning, the voltage is 10 - 20 kV, the flow rate is 0.5 - 1.5 mL / h, the inner diameter of the needle is 0.4 - 0.55 mm, the humidity is 30 - 65%, the distance from the needle to the roller receiver is 15 - 20 cm, and the electrospinning time is 30 - 60 min.

[0036] Beneficial effects: With the above settings in this solution, it is convenient to prepare uniform, continuous, and good-performance ZIF-8@PVDF-TrFE nanofibers. Specifically, an appropriate voltage can provide sufficient driving force to form a stable jet of the electrospinning solution; the appropriate flow rate, inner diameter of the needle, humidity, receiving distance, and electrospinning time cooperate with each other to control the diameter, morphology, and thickness of the fibers. Through long-term experiments, the applicant found that if the voltage is too high or too low, the flow rate is too fast or too slow, the inner diameter of the needle is inappropriate, the humidity is abnormal, the receiving distance is too far or too close, or the electrospinning time is too long or too short, problems such as uneven fiber thickness, breakage, and adhesion will occur due to the change of electrospinning conditions, affecting the sound-absorbing performance of the composite nanofiber membrane. Description of the Drawings

[0037] Figure 1 This is the XRD pattern of the ZIF-8 powder, PVDF-TrFE, and their composite nanofiber ZIF-8@PVDF-TrFE prepared in Example 1 of the present invention.

[0038] Figure 2 This shows the influence of different PVDF-TrFE concentrations on the morphology of ZIF-8@PVDF-TrFE nanofibers in Example 1 of the present invention (the PVDF-TrFE concentrations in a - d are 10%, 12%, 14%, and 16% in sequence).

[0039] Figure 3 Effect of different ZIF-8 concentrations on the morphology of ZIF-8@PVDF-TrFE nanofibers in Example 1 of the present invention (the ZIF-8 concentrations in a - e are 0.4%, 0.83%, 1.67%, 3% and 5% of PVDF-TrFE in sequence).

[0040] Figure 4 Effect of voltage in the range of 15 - 20 KV on the morphology of ZIF-8@PVDF-TrFE nanofibers in Example 1 of the present invention (the voltages in a - c are 15 KV, 17 KV and 20 KV in sequence).

[0041] Figure 5 Effect of different nozzle inner diameters on the morphology of ZIF-8@PVDF-TrFE nanofibers in Example 1 of the present invention (the nozzle inner diameters in a - d are 0.41 mm, 0.51 mm, 0.6 mm and 0.7 mm in sequence, e is pure PVDF-TrFE as a control, and f is pure ZIF-8 as a control).

[0042] Figure 6 Fourier transform infrared (FT-IR) spectra of ZIF-8@PVDF-TrFE nanofibers and the control group in Example 1 of the present invention (a is the spectrum of ZIF-8@PVDF-TrFE nanofibers and the control group; b is the spectrum of ZIF-8@PVDF-TrFE nanofibers under different voltages).

[0043] Figure 7 β-phase content of PVDF-TrFE and ZIF-8@PVDF-TrFE nanofibers under different conditions in Example 1 of the present invention.

[0044] Figure 8 X-ray photoelectron spectroscopy (XPS) of ZIF-8@PVDF-TrFE nanofibers and control samples in Example 1 of the present invention (a is the full XPS spectrum of ZIF-8@PVDF-TrFE nanofibers and control samples; b and c are the C1s spectra of ZIF-8@PVDF-TrFE and PVDF-TrFE respectively).

[0045] Figure 9 Sound absorption of ZIF-8@PVDF-TrFE nanofiber membranes (NM) with different thicknesses combined with 3 cm thick foam in the mid - low frequency range in Example 1 of the present invention (a is the sound absorption coefficient in the low frequency range of 50 - 1000 Hz, b is the sound absorption coefficient in the mid - frequency range of 1000 - 3000 Hz, c is the average sound absorption coefficient in the low frequency range, and "F" in the figure is the foam board and "M" is the nanofiber membrane).

[0046] Figure 10Absorption characteristics of the composite structure of ZIF-8@PVDF-TrFE nanofiber membrane (NM) and microperforated plate (MPP) in Example 1 of the present invention in the frequency range of 50 - 1000 Hz (a is a cavity with a thickness of 1 cm, b is a cavity with a thickness of 2 cm, c is a cavity with a thickness of 3 cm, d is the average absorption coefficient in the low-frequency range; in the figure, "C" is the cavity depth, "MPP" is the microperforated plate, "M" is the nanofiber membrane).

[0047] Figure 11 Absorption performance of the composite of ZIF-8@PVDF-TrFE nanofiber membrane (NM), foam (F) and microperforated plate (MPP) in Example 1 of the present invention (a is that the foam is at the rear, b is that the foam is between the cavity and the MPP, c is that the foam is placed at the front, d is the average SAC in the low-frequency range). Detailed implementation manners

[0048] The present invention will be further described in detail below with reference to the embodiments, but the implementation manners of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used can be obtained from commercial channels.

[0049] Example 1

[0050] This solution provides a composite nanofiber membrane sound-absorbing material, which includes obtaining a spinning solution by dispersing a metal-organic framework material ZIF-8 and a ferroelectric polymer PVDF-TrFE (the composition of PVDF-TrFE is 70 / 30 mol%) in a solvent, and the ZIF-8@PVDF-TrFE nanofiber membrane is obtained by electrospinning the spinning solution. Among them, the concentration of PVDF-TrFE in the spinning solution is 12 - 16 wt%, and the concentration of ZIF-8 in the spinning solution is 0.4 - 1.67 wt% of the concentration of PVDF-TrFE (in this example, the concentration of PVDF-TrFE in the spinning solution is 12%, and the concentration of ZIF-8 in the spinning solution is 1.67 wt% of the concentration of PVDF-TrFE). The thickness of the ZIF-8@PVDF-TrFE nanofiber membrane is 0.25 - 0.75 mm. The average absorption coefficient of the ZIF-8@PVDF-TrFE nanofiber membrane in the frequency range of 50 - 1000 Hz is 0.58 - 0.63.

[0051] This solution also provides a preparation method of the composite nanofiber membrane sound-absorbing material for preparing the above ZIF-8@PVDF-TrFE nanofiber membrane, including the following steps:

[0052] Step 1. Preparation of ZIF-8: Weigh 4.462 g of zinc nitrate hexahydrate and 4.926 g of 2-methylimidazole and dissolve them in 150 mL of methanol solution respectively, which are denoted as solution A (methanol solution of zinc nitrate) and solution B (methanol solution of 2-methylimidazole), and ultrasonicate until completely dissolved at room temperature. According to the molar ratio of 2-methylimidazole to Zn being 3 - 5 (specifically 4 in this example), dropwise add solution B into solution A at 25 ± 3 °C under stirring. After complete addition, continue stirring for 60 min, then let it stand at room temperature for 20 - 24 h to obtain a mixed solution. Centrifuge the mixed solution using a high-speed centrifuge (4500 - 8000 rpm, 5 - 10 min), discard the supernatant, wash three times with methanol to obtain the solid component. The solid component is then dried (liquid nitrogen drying in this example) and ground to obtain pure nano ZIF-8 white powder for standby.

[0053] Step 2. Preparation of ZIF-8 dispersion: Disperse 0.3 g of nano ZIF-8 powder in 10 ml of acetone, and then add a small amount of PA and PFOES (the dosages of PA and PFOE are 4 wt% and 1 wt% of nano ZIF-8 respectively). Ultrasonically mix at room temperature for 30 min to obtain a uniform ZIF-8 dispersion. This stage is convenient for generating significant shock waves and microjets near the particle surface, which can reduce the surface energy of these particles and effectively prevent their agglomeration.

[0054] Step 3. Preparation of spinning solution: Weigh a certain amount of PVDF-TrFE powder and dissolve it in DMF to prepare a PVDF-TrFE solution, magnetically stir for 6 - 8 h for rapid dispersion. After mixing evenly, introduce the ZIF-8 dispersion into the PVDF-TrFE solution and mix. The mixed solution is treated with a magnetic stirrer (temperature set at 80 °C, rotation speed 400 r / min) for 6 - 8 h to make it fully dissolve, and then ultrasonically stir for 30 min to ensure uniform suspension; finally, let it stand at room temperature for 12 - 16 h to complete the reaction and fully discharge the bubbles in the solution, obtaining the spinning solution for standby. In this example, the concentration of PVDF-TrFE in the spinning solution is 12%, and the concentration of ZIF-8 is 1.67% of the PVDF-TrFE concentration.

[0055] Step 4. Electrospinning: Use an electrospinning machine, set important parameters such as voltage of 15 - 20 kV (specifically 20 V in this example), flow rate of 1.2 mL / h, inner diameter of the needle of 0.4 - 0.55 mm (specifically 0.51 mm in this example), humidity of 30 - 65%, and distance from the needle to the roller receiver of 18 cm, and then carry out electrospinning. After the electrospinning process is completed, carefully take out the fiber membrane from the receiving cylinder and place it in an oven at 65 °C for drying for 4 h to obtain the ZIF-8@PVDF-TrFE nanofiber membrane.

[0056] The thickness of the nanofiber membrane can be controlled by adjusting the spinning time. As a reference, the spinning time in this solution is 30 - 60 min.

[0057] Without adding the ZIF-8 dispersion liquid, the PVDF-TrFE nanofiber membrane can be prepared according to the above steps.

[0058] Experimental Example 1: Feature Description

[0059] The crystalline phases of the ZIF-8@PVDF-TrFE nanofiber membrane prepared in Example 1 were determined by Fourier transform infrared spectroscopy (FT-IR, Thermos Scientific, Nicoleti S20) and X-ray diffraction (XRD, Shimadzu, XRD-600). A field emission scanning electron microscope (FE-SEM, JEOL JSM-7800F) was used to study the surface morphology of the thin film and analyze the dispersion of ZIF-8 in the composite thin film. X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha) was used to examine the surface element composition and chemical state. The results are shown in Figures 1 to 8 。

[0060] (1) Crystal phases of ZIF-8 and PVDF-TrFE

[0061] Figure 1 shows the XRD patterns of ZIF-8 powder, PVDF-TrFE, and their composite nanofiber ZIF-8@PVDF-TrFE. The experimental data show that the diffraction pattern of ZIF-8 exhibits distinct peaks at 2θ values of 7.3°, 10.37°, 12.6°, 14.7°, 16.4°, and 18.0°, which confirms the successful synthesis of ZIF-8 crystals. In Figure 1 (b), an obvious carbon diffraction peak is observed at 2θ = 20°, which is attributed to the presence of the poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) polymer. The X-ray diffraction (XRD) pattern of the ZIF-8@PVDF-TrFE composite nanofiber contains the characteristic peaks of both ZIF-8 and PVDF-TrFE, indicating that these materials have been successfully integrated into a single composite structure. In addition, the characteristic diffraction peaks of ZIF-8 corresponding to the (002), (112), and (222) crystal planes are retained, indicating that the electrospinning process did not cause a change in the crystal structure of ZIF-8 in the composite nanofiber.

[0062] (2) Morphology of ZIF-8@PVDF-TrFE nanofibers

[0063] Figures 2 to 5Shows the scanning electron microscope (SEM) images of ZIF-8@PVDF-TrFE nanofibers prepared under different conditions during the electrospinning process in Step 4. The electrospinning process was studied by examining four key parameters, namely the PVDF-TrFE concentration, the ZIF-8 concentration, the applied voltage, and the inner diameter of the nozzle. The morphology of the composite nanofibers was evaluated according to three criteria: the degree of encapsulation of ZIF-8 particles, the integrity of the nanofibers, and the uniform dispersion of ZIF-8 within the fibers.

[0064] Specifically, Figure 2 (a - d) studied the effect of different PVDF-TrFE concentrations on the morphology of ZIF-8@PVDF-TrFE nanofibers (the PVDF-TrFE concentrations in (a - d) are 10%, 12%, 14%, and 16% in sequence). When the concentration was 10%, the fibers were flat and showed fractures. When the concentration increased to 12%, the fibers became round with relatively uniform protrusions on the surface, indicating that ZIF-8 was successfully encapsulated within the fibers and evenly distributed. As the PVDF-TrFE concentration further increased, the fibers became significantly thicker, presenting a circular cross-section and a wrinkled surface, indicating a deeper encapsulation of ZIF-8 due to the thickening of the fibers.

[0065] Figure 3 (a - e) shows the effect of different ZIF-8 concentrations on the morphology of ZIF-8@PVDF-TrFE nanofibers (the ZIF-8 concentrations in (a - e) are 0.4%, 0.83%, 1.67%, 3%, and 5% of PVDF-TrFE in sequence). When the ZIF-8 concentration was 0.4% of PVDF-TrFE, there were very few protrusions on the fiber encapsulation. As the concentration increased, the number of protrusions on the fiber encapsulation also increased. However, when the ZIF-8 concentration exceeded 1.67% of PVDF-TrFE, the nanofibers began to fracture. This indicates a decrease in the toughness of the fibers and a corresponding increase in brittleness. In addition, ZIF-8 particles appeared on the surface of the nanofibers, meaning that the polymer did not fully encapsulate ZIF-8, exposing the filler material inside the fibers.

[0066] Figure 4 (a - c) shows the effect of voltage in the range of 15 - 20 KV on the morphology of ZIF-8@PVDF-TrFE nanofibers (the voltages in (a - c) are 15 KV, 17 KV, and 20 KV in sequence). ZIF-8 nanoparticles were uniformly encapsulated within the fibers. As the voltage increased, the fibers became thinner and were more prone to breakage.

[0067] Figure 5(a - f) depict the influence of the inner diameter of the nozzle on the morphology of ZIF-8@PVDF-TrFE nanofibers (the inner diameters of the nozzles in (a - d) are 0.41 mm, 0.51 mm, 0.6 mm, and 0.7 mm in sequence, e is pure PVDF-TrFE as a control, and f is pure ZIF-8 as a control). When the inner diameter of the nozzle is 0.41 mm, the prepared fibers are slender and disorderly, and there are a large number of nanoparticles on their surfaces. When the inner diameter is 0.51 mm, the diameters of the nanofibers are uniform, and the nanoparticles are evenly wrapped. On the contrary, when the inner diameter is 0.6 mm or 0.7 mm, a large number of bead-like structures appear, which are characterized by uneven particle wrapping.

[0068] (3) Fourier Transform Infrared Spectroscopy (FT-IR) of ZIF-8@PVDF-TrFE Nanofibers

[0069] Figure 6 Shows the Fourier Transform Infrared (FT-IR) spectra of ZIF-8@PVDF-TrFE nanofibers and the control groups (a is the spectra of ZIF-8@PVDF-TrFE nanofibers and the control groups; b is the spectra of ZIF-8@PVDF-TrFE nanofibers under different voltages). Among them, the ZIF-8@PVDF-TrFE nanofibers were prepared under the conditions of a PVDF-TrFE concentration of 12%, a ZIF-8 concentration of 1.67% of PVDF-TrFE, a voltage of 18 KV, and a needle inner diameter of 0.51 mm. Figure 6 (a) shows that the transmission peaks of PVDF-TrFE and ZIF-8@PVDF-TrFE at 613, 762, and 976 correspond to the α-phase of PVDF (Prajapati et al., 2025). The peaks at 840, 874, 1173, 1275, and 1400 correspond to the β-phase of PVDF (Meng et al., 2025). The peaks in the range of 600 - 1500 are related to the bending vibration mode of the imidazole ring of ZIF-8. On the composite nanofibers, this peak appears at 693 and 759. This indicates that ZIF-8 and the polymer have been successfully mixed, and their chemical structures have not undergone significant changes or damage, which means that the original properties and functions of ZIF-8 and the polymer remain unchanged.

[0070] Figure 6 (b) demonstrates the influence of voltage on the FT-IR spectra of the composite nanofibers. Figure 7 Shows the β-phase content of poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) under different conditions. It is worth noting that the voltage change has no effect on the position and relative height of the peaks. According to the Lambert-Beer law (Elorika et al., 2025), the β-phase content in PVDF-TrFE was calculated and shown in Figure 7Among them. Compared with pure PVDF-TrFE nanofibers, at a voltage of 18 kV, the β-phase content in ZIF-8@PVDF-TrFE nanofibers increased by 12%, reaching 80.6%, which is quite high compared with peer research (Deng et al., 2025; Li, J. et al., 2022; Singh et al., 2021; Wang et al., 2024). On the contrary, the effect of voltage change on the β-phase content of ZIF-8@PVDF-TrFE is extremely small.

[0071] (4) X-ray photoelectron spectroscopy (XPS) analysis of ZIF-8@PVDF-TrFE nanofibers

[0072] X-ray photoelectron spectroscopy (XPS) was used to detect the surface element composition of ZIF-8@PVDF-TrFE composite nanofibers. Figure 8 Figure 8 shows the X-ray photoelectron spectroscopy (XPS) of ZIF-8@PVDF-TrFE nanofibers and control samples (a is the full XPS spectrum of ZIF-8@PVDF-TrFE nanofibers and control samples; b and c are the C1s spectra of ZIF-8@PVDF-TrFE and PVDF-TrFE, respectively). In the full spectrum, the characteristic peaks of ZIF-8 at 1045, 1022, 531, 399, and 285 eV correspond to Zn2p1, Zn2p3, O1s, N1s, and C1s, respectively. For ZIF-8@PVDF-TrFE, the peaks at 833, 688, 532, and 286 eV correspond to FKL1, F1s, O1s, and C1s, respectively, and no obvious peak of zinc element was observed. Combining with the scanning electron microscope (SEM) image, this phenomenon indicates that ZIF-8 is completely wrapped inside the fiber and not exposed on the fiber surface.

[0073] Experimental Example 2: Sound absorption coefficient

[0074] The sound absorption coefficient (SAC) of ZIF-8@PVDF-TrFE composite membranes and control samples was studied using an impedance tube with a two-microphone technique. The device is equipped with two tubes, one with a diameter of 10 cm and the other with a diameter of 3 cm, which are used to measure the sound absorption coefficient in the frequency bands of 50 - 1000 Hz and 500 - 6300 Hz, respectively. All samples were cut into sizes matching the diameters of these tubes to ensure consistent boundary conditions for all experiments. The tests followed the standard procedure of ASTM E1050-19 of the American Society for Testing and Materials (ASTM, 2012). Each sample was tested at least three times, and the average value was reported. The results are shown in Figures 9 to 11 。

[0075] The low-frequency average sound absorption coefficient (LASAC) was calculated by formula (1):

[0076]

[0077] In the formula, F1 and F2 respectively represent the starting frequency and the ending frequency, which are 50 Hz and 1000 Hz respectively in the low-frequency range. α represents the sound absorption coefficient at the corresponding frequency.

[0078] The Noise Reduction Coefficient (NRC) is used to evaluate the effectiveness of sound insulation materials in isolating and suppressing sound waves. It is defined as the arithmetic mean of the sound absorption coefficients measured at the center frequencies of 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz, and is calculated by formula (2):

[0079]

[0080] In the formula, αi is the value of the sound absorption coefficient at the frequency of i Hz, and i includes 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz.

[0081] (1) Sound absorption performance of ZIF-8@PVDF-TrFE membranes containing foam

[0082] Figure 9 Shows the sound absorption of ZIF-8@PVDF-TrFE nanofiber membranes (NM) combined with 3 cm thick foam in the mid-low frequency range (a is the sound absorption coefficient in the 50-1000 Hz low-frequency range, b is the sound absorption coefficient in the 1000-3000 Hz mid-frequency range, c is the average sound absorption coefficient in the low-frequency range, "F" in the figure is the foam board, and "M" is the nanofiber membrane), where the ZIF-8@PVDF-TrFE nanofiber membrane serves as the sound receiving surface. Under this structure, compared with the control foam group, the sound absorption performance is significantly improved in the range of 50-2000 Hz. As the thickness of the nanofiber membrane increases, the peak value of the sound absorption coefficient (SAC) gradually increases and shifts towards the low frequency, which is consistent with the previous research results (Shao and Yan, 2022; Xiang et al., 2011). For the nanofiber membrane with a thickness of 0.75 mm, the peak value of the sound absorption coefficient reaches 0.98 at 1034 Hz.

[0083] The Low-frequency Average Sound Absorption Coefficient (LASAC) is a key parameter in acoustic analysis, which reflects the sound absorption ability of materials in the low-frequency range. This coefficient increases from 0.15 of the baseline foam material to 0.40 of the 0.75 mm thick nanofiber membrane (NM) composite material, and increases with the increase in the thickness of the nanofiber membrane. In addition, the Noise Reduction Coefficients (NRCs) also increase from 0.30 of the single foam material to 0.43 of the 0.75 mm nanofiber membrane composite material. Materials or structures with a Sound Absorption Coefficient (SAC) exceeding 0.5 are considered to have excellent sound absorption performance. Specifically, the composite materials with nanofiber membrane thicknesses of 0.5 mm and 0.75 mm exhibit this characteristic in the frequency ranges of 797 - 2297 Hz and 659 - 2103 Hz respectively, indicating that for the 0.75 mm thick nanofiber membrane layer, the size of the sound absorption material can be reduced to 1 / 17 of the wavelength.

[0084] This excellent sound absorption performance can be attributed to the synergistic effect of multiple factors. First of all, the high specific surface area of the nanofiber membrane is conducive to increasing the collision and friction with low-frequency sound waves. The addition of ZIF-8 nanofillers into the polymer matrix enhances the internal friction, triggering phenomena such as polymer chain segment loss, loss between the polymer and the filler, and mutual loss between the fillers, thus further increasing the internal friction. In addition, the nanoscale fibers and ZIF-8 particles dissipate part of the sound energy through resonance at low frequencies. Moreover, the piezoelectric characteristics of PVDF-TrFE transfer part of the energy during the propagation of sound waves, resulting in rapid energy consumption, namely piezoelectric transfer. After adding ZIF-8, the β-phase content reaches 80.6%, further enhancing this piezoelectric effect. Generally speaking, the nanofiber membrane composite foam structure works based on the viscous resistance absorption mechanism, and its acoustic performance improves with the increase in the membrane thickness.

[0085] (2) Sound Absorption Performance after the Composite of ZIF-8@PVDF-TrFE Membrane and Microperforated Panel

[0086] The microperforated panel (MPP) is a typical traditional sound absorption structure, which is especially effective for low-frequency noise. Circular perforations are processed on the stainless steel plate and arranged in a square pattern. The perforation diameter is 0.75 mm, the hole spacing is 5.00 mm, and the plate thickness is 0.5 mm. The perforation process uses laser cutting, and the perforation rate is 1%. The cavity depths are set to 1 cm, 2 cm, and 3 cm respectively. Figure 10 (a - d) show the sound absorption characteristics of the composite structure of ZIF-8@PVDF-TrFE nanofiber membrane (NM) and microperforated panel in the frequency range of 50 - 1000 Hz (a is the 1 cm thick cavity, b is the 2 cm thick cavity, c is the 3 cm thick cavity, d is the average sound absorption coefficient in the low-frequency range; in the figure, "C" is the cavity depth, "MPP" is the microperforated panel, "M" is the nanofiber membrane).

[0087] A separate micro-perforated plate was used as the control group. It can be observed that after adding the nanofiber membrane composite, the sound absorption performance was significantly improved. As the thickness of the nanofiber membrane layer increased, the sound absorption curve gradually shifted towards the low-frequency direction, although the maximum sound absorption coefficient decreased. When the thickness of the nanofiber membrane layer remained unchanged, the sound absorption performance increased with the increase in the depth of the back cavity.

[0088] Figure 10 (d) shows the variation of the low-frequency average sound absorption coefficient (LASAC) at different nanofiber membrane thicknesses. As the membrane thickness increased, the low-frequency average sound absorption coefficient first increased and then decreased, reaching a maximum value of 0.58 when the thickness of the nanofiber membrane layer was 0.25 mm. The thicker the nanofiber membrane, the lower the frequency corresponding to a sound absorption coefficient of 0.5, which could reach as low as 310 Hz. For a 0.25-mm-thick nanofiber membrane layer, the lowest frequency corresponding to a sound absorption coefficient of 0.5 was 355 Hz, corresponding to a wavelength of 0.958 m, which made the size of the sound absorption structure reach a sub-wavelength scale of approximately 1 / 31 of the wavelength.

[0089] (3) Sound absorption performance of the ZIF-8@PVDF-TrFE membrane composite with foam and micro-perforated plate

[0090] In addition, the researchers studied the sound absorption performance of a composite structure composed of a nanofiber membrane (NM), foam, and a micro-perforated plate, and the results are shown in Figure 11 (a~d) (where a is the foam at the rear, b is the foam between the cavity and the MPP, c is the foam at the front, and d is the average SAC in the low-frequency range). The uncomposite nanofiber membrane structure was used as the control group. Similar to the above situation, after adding the nanofiber membrane composite, the sound absorption performance was significantly improved. This improvement effect varied depending on the positions of the three components and the depth of the cavity. When the nanofiber membrane was used as the sound absorption surface, the foam as the back, and the micro-perforated plate as the intermediate layer, the sound absorption coefficient (SAC) was positively correlated with the increase in the depth of the cavity, and the sound absorption frequency shifted towards the low-frequency direction. When the depth of the cavity was 3 cm, the sound absorption coefficient could reach 0.5 at a noise frequency as low as 205 Hz. When the foam was located between the cavity and the micro-perforated plate, the increase in the depth of the cavity gradually increased the sound absorption coefficient and decreased the sound absorption frequency. The low-frequency average sound absorption coefficient (LASAC) reached a peak value of 0.63, and the frequency range with a sound absorption coefficient greater than 0.5 extended from 225 Hz to above 1000 Hz, indicating an unusually wide sound absorption bandwidth. When the foam was used as the sound absorption surface, the micro-perforated plate and the cavity formed the back lining surface, and there was a 1-cm-thick cavity between the foam and the nanofiber membrane, its sound absorption performance was even lower than that of the control group with a zero-depth back lining cavity. However, when the depth of the back lining cavity exceeded 1 cm, the maximum sound absorption coefficient exceeded 0.9. Although the sound absorption frequency band with a sound absorption coefficient greater than 0.5 was still very wide, the lowest frequency only reached 351 Hz.

[0091] The composite structure composed of these three components exhibits excellent performance. It is worth noting that by combining these three components, with the foam placed between the cavity and the micro-perforated plate and the nanofiber membrane facing the sound source, the optimal structure can be obtained. Specifically, when the thickness of the nanofiber membrane layer is 0.6 mm and the depth of the cavity is 3 cm, the average sound absorption coefficient of this structure at low frequencies reaches 0.63, with a broad low-frequency sound absorption bandwidth, and the lowest frequency can reach 225 Hz, which is quite remarkable. It is worth mentioning that the size of this optimized absorber is only 1 / 25 of the wavelength.

[0092] Different from the composite material containing foam, the composite material of the nanofiber membrane and the micro-perforated plate works through the resonance absorption mechanism and exhibits excellent sound absorption performance at low frequencies. When these three components are combined together, the absorption mechanism changes to a combination of resonance and viscous resistance, thus achieving excellent low-frequency sound absorption effect and broadening the sound absorption bandwidth.

[0093] Experimental Example 3: Comparison with Literature Data

[0094] In this scheme, the average sound absorption coefficient (SAC) of the ZIF-8@PVDF-TrFE nanofiber membrane (NMs) was compared with the values in the existing literature, and the results are shown in Table 1.

[0095] Table 1 Comparison Results of the Sound Absorption Performance Values of the ZIF-8@PVDF-TrFE Nanofiber Membrane in this Scheme and the Existing Literature Data

[0096]

[0097] The comparison results show that the ZIF-8@PVDF nanofiber has a significant improvement in acoustic performance compared with traditional solid materials. And the sound absorption coefficient value in this scheme was measured under low-frequency noise levels, representing the lowest frequency range involved in the study of sound absorption performance, and was obtained under the condition of the thinnest nanofiber membrane thickness (i.e., 0.25 mm) used in this scheme.

[0098] In summary, this scheme successfully integrates ZIF-8 uniformly into PVDF-TrFE nanofibers. The resulting fibers are circular, with a uniform diameter, protrusions on the surface and no damage. The ZIF-8@PVDF-TrFE nanofiber membrane (NM) significantly improves the sound absorption performance of acoustic foam and micro-perforated plate (MMP), especially in the low-frequency range. Specifically as follows:

[0099] (1) When the nanofiber membrane is combined with the foam, the low-frequency average sound absorption coefficient (LASAC) increases with the increase of the membrane thickness, up to 0.4 at most. When the thickness of the nanofiber membrane is 0.75 mm, the maximum sound absorption coefficient (SAC) reaches 0.98 at 1034 Hz.

[0100] (2) When compounded with the micro-perforated plate, as the membrane thickness increases, the sound absorption curve gradually shifts towards the low-frequency direction; for nanofiber membranes with the same thickness, the sound absorption performance improves with the increase in cavity depth. The average low-frequency sound absorption coefficient first increases and then decreases with the increase in membrane thickness, reaching a peak value of 0.58 when the membrane thickness is 0.25 mm.

[0101] (3) When all three components are compounded, the sound absorption performance varies depending on the positions of the nanofiber membrane, foam, and micro-perforated plate, as well as the cavity depth. When the foam is placed between the cavity and the micro-perforated plate, as the cavity depth increases, the sound absorption coefficient increases and the sound absorption frequency decreases. The average low-frequency sound absorption coefficient can reach up to 0.63, and the sound absorption coefficient remains above 0.5 starting from 225 Hz.

[0102] The material obtained by the innovation of this solution has excellent sound absorption performance and a broad low-frequency sound absorption bandwidth, providing a new solution for controlling low-frequency noise under conditions of limited weight and volume.

[0103] The reference information in the article is as follows:

[0104] Prajapati et al., 2025: Prajapati, M., Kalla, S., Sivaiah, A., 2025. A superhydrophobic membrane based on CuBTC@PVDF for perfluorooctanoic acid (PFHpA) retention by membrane distillation. Process Safety and Environmental Protection, 194, 152 - 163.

[0105] Meng et al., 2025: Meng, F., Liu, C., Guo, J., Wang, J., Zhao, L., Xu, H., Chen, X., Wang, Y., Zhu, Z., Zheng, Z., Cui, P., 2025. Separation and Purification Technology, 353, 128434.

[0106] Elorika et al., 2025: Elorika, P., Anwar, Sharmistha, Roy, A., Anwar, Shahid, 2025. Flexible polyvinylidene fluoride-barium calcium titanate (Ba 0.97 Ca 0.03 TiO 3 ) polymer-ceramic composite films for energy storage, biosensing, mechanical sensing, and ultraviolet-visible light protection. Materials Research Bulletin, 181, 113116.

[0107] Deng, X., Wu, Z., Yu, X., Wang, M., Zang, D., Long, Y., Guo, N., Weng, L., Liu, Y., Gao, J., 2025. Preparation and properties of triboelectric nanogenerators based on poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) / polymethyl methacrylate (PMMA) electrospun films. Advanced Composite Materials and Hybrid Materials, Vol. 8, pp. 1-18.

[0108] Li, J., Zhou, G., Hong, Y., He, W., Wang, S., Chen, Y., Wang, C., Tang, Y., Sun, Y., Zhu, Y., 2022. Highly sensitive and flexible wearable piezoelectric motion sensors based on lanthanide-promoted β-phase poly(vinylidene fluoride). Sensors and Actuators A: Physical, Vol. 337, p. 113415.

[0109] Singh, R.K., Lye, S.W., Miao, J., 2021. Comprehensive study of electrospinning parameters for enhancing the β-phase content in poly(vinylidene fluoride) (PVDF) nanofibers. Polymer (Guildford), Vol. 214, p. 123366.

[0110] Wang, L., Yan, F., Pan, J., He, X., Chen, C., Boda, M.A., Yi, Z., 2024. Boosting the photo-driven pyroelectric response of poly(vinylidene fluoride) by constructing manganese-doped sodium bismuth zirconate titanate-calcium bismuth titanate (BZT-BCT) / poly(vinylidene fluoride) (PVDF) composites. Journal of Materials Chemistry C, pp. 393-402.

[0111] ASTM, 2012. Standard Test Method for Measuring the Impedance and Absorption of Acoustical Materials, pp. 1-6.

[0112] Shao, X., Yan, X., 2022. Sound absorption properties of multilayer composites based on nanofiber membranes. Applied Acoustics, Vol. 200, p. 109029.

[0113] Xiang, H.F., Tan, S.X., Yu, X.L., Long, Y.H., Zhang, X.L., Zhao, N., Xu, J., 2011. Sound absorption properties of electrospun polyacrylonitrile nanofiber membranes. Chinese Journal of Polymer Science (English Edition), Vol. 29, pp. 650-657.

[0114] Chen et al., 2025: Chen, Chunyan, Yue, J., Zhou, J., Liu, Q., Tang, Y., Chen, Chunlin, Xiao, G., 2025. Removal of hexavalent chromium (Cr(VI)) by coupling adsorption and photocatalytic degradation using silver / zeolitic imidazolate framework-8 / polyvinylidene fluoride (Ag / ZIF-8 / PVDF) membranes. Chemical Engineering & Technology - Process Intensification, 208, 110120.

[0115] Fan et al., 2023: Fan, Z., Wu, S., Fang, K., Tang, F., Zhang, L., Huang, F., 2023. High - efficiency sound absorption and electro - acoustic conversion in heteronanofibers: A two - pronged approach for full - frequency noise reduction. Journal of Materials Chemistry A, pp. 13378 - 13388.

[0116] Zhao - xuan et al., 2021: Zhao - Xuan, D., Ying, W., 2021. Optimization and characterization of polyurethane electrospun nanofilm for sound - absorbing multilayer sheet surfaces. Journal of Macromolecular Science Part B: Physics, Vol. 60, pp. 647 - 662.

[0117] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well - known in the art are not described in detail here. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. A composite nanofiber membrane sound-absorbing material, characterized in that: The method comprises dispersing a metal organic framework material ZIF-8 in acetone to obtain a ZIF-8 dispersion; dispersing a ferroelectric polymer PVDF-TrFE in a solvent DMF to obtain a PVDF-TrFE solution; then dropping the ZIF-8 dispersion into the PVDF-TrFE solution to obtain a spinning solution, and electrospinning the spinning solution to obtain a ZIF-8@PVDF-TrFE nanofiber membrane.

2. The composite nanofiber membrane sound absorbing material according to claim 1, characterized in that: The concentration of PVDF-TrFE in the spinning solution is 12-16 wt %, and the concentration of ZIF-8 in the spinning solution is 0.4-1.67 wt % of the concentration of PVDF-TrFE.

3. The composite nanofiber membrane sound absorbing material according to claim 2, characterized in that: The composition of the PVDF-TrFE is 70 / 30 by mole percent.

4. The composite nanofiber membrane sound absorbing material according to claim 3, characterized in that: The thickness of the ZIF-8@PVDF-TrFE nanofiber membrane is 0.25-0.75 mm.

5. The composite nanofiber membrane sound absorbing material according to claim 4, characterized in that: The average sound absorption coefficient of the ZIF-8@PVDF-TrFE nanofiber membrane in the frequency range of 50 to 1000 Hz is 0.58 to 0.

63.

6. A method for preparing a composite nanofiber membrane sound-absorbing material, characterized in that: The preparation of the ZIF-8@PVDF-TrFE nanofiber membrane according to any one of claims 1 to 5 comprises the following steps: Step 1, preparation of ZIF-8: zinc nitrate and 2-methylimidazole are dispersed in methanol solutions, respectively, denoted as solution A and solution B, and are ultrasonicated at room temperature until completely dissolved; solution B is added dropwise to solution A under stirring, and after complete addition, stirring is continued for 60 minutes and then allowed to stand at room temperature for 20 to 24 hours to obtain a mixed solution; the mixed solution is centrifuged, washed with methanol, dried, and ground to obtain nano ZIF-8 powder; Step 2, preparing ZIF-8 dispersion: dispersing nano ZIF-8 powder in acetone, adding PA and PFOES, and mixing by ultrasonication at room temperature to obtain ZIF-8 dispersion; Step 3, preparing a spinning solution: dispersing PVDF-TrFE powder in a DMF solution to obtain a ZIF-8 dispersion; then dispersing a ferroelectric polymer PVDF-TrFE in a solvent DMF to obtain a PVDF-TrFE solution, and then dropping the ZIF-8 dispersion into the PVDF-TrFE solution to obtain a spinning solution; Step 4: Electrospinning: The spinning solution is spun by an electrospinning machine to obtain ZIF-8@PVDF-TrFE nanofibers.

7. The method for preparing a composite nanofiber membrane sound absorbing material according to claim 6, characterized in that: In step 1, the molar ratio of 2-methylimidazole to Zn in the mixed solution is 3-5:1; the stirring speed is 250-500 rpm, and the centrifugal treatment is centrifuged at 4500-8000 rpm for 5-10 min.

8. The method for preparing a composite nanofiber membrane sound absorbing material according to claim 6, characterized in that: In step 2, the addition amounts of PA and PFOE are 4-5wt% and 1-2wt% of the nano ZIF-8 powder respectively; and the ultrasonic mixing time is 30-45 minutes.

9. The method for preparing a composite nanofiber membrane sound absorbing material according to claim 6, characterized in that: In step three, the magnetic stirring treatment is heating mixing at a temperature of 80 to 85° C. and a rotation speed of 400 to 500 r / min for 6 to 8 hours; the room temperature standing time is 12 to 16 hours.

10. The method for preparing a composite nanofiber membrane sound absorbing material according to claim 6, characterized in that: In step 4, during the electrospinning, the voltage is 10-20 kV, the flow rate is 0.5-1.5 mL / h, the inner diameter of the needle is 0.4-0.55 mm, the humidity is 30-65%, and the distance from the needle to the drum is 15-20 cm.

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