Amino-enhanced polylactic acid-based nanofiber membrane, and preparation method and application thereof

Abstract

This invention discloses an amino-reinforced polylactic acid (PLA) nanofiber membrane, its preparation method, and its application, belonging to the field of air filtration membrane material technology. This invention obtains an amino-reinforced PLA fiber membrane (MSC-PLA fiber membrane) by introducing highly active amino groups to increase hydrogen bond density and promote stereocomposite formation. This provides the basis for a triboelectric nanogenerator. By combining it with an electrode membrane, it can stably collect charges and form an electric potential field. The combined membrane structure constitutes a triboelectric nanogenerator, resulting in an amino-reinforced PLA nanofiber membrane with high electroactivity, antimicrobial activity, excellent PMs filtration effect, and low filtration resistance. Furthermore, long-term storage does not affect the filter material potential.

Description

Technical Field

[0001] This invention relates to the field of air filter membrane material technology, specifically to an amino-reinforced polylactic acid-based nanofiber membrane, its preparation method, and its application. Background Technology

[0002] With the rapid development of global industrialization, air pollution has become an increasingly serious problem. To prevent air pollutants from harming human health, there is an urgent need to develop air filter membranes that offer long-lasting microbial inactivation, low filtration resistance, and excellent filtration performance. Existing air filter membranes are made from polypropylene fibers, which increase particulate matter filtration efficiency by utilizing mechanical filtration and the capture of particles by charged fibers. However, polypropylene is inherently difficult to degrade, thus it is not conducive to the environmental protection concept of green and sustainable development.

[0003] Polylactic acid (PLA) is a biodegradable material made from starch extracted from plants. The carbon dioxide and water produced during its degradation in nature can be reused by plants through photosynthesis, embodying a recyclable and sustainable green cycle. Due to its excellent mechanical properties, good biocompatibility, and non-toxic and mild nature, PLA has broad application prospects in the field of air filtration. Furthermore, PLA exhibits shear triboelectric properties due to the chiral centers in its molecular chain. Voltage can be generated through mechanical action without the need for external electric field polarization treatment; this method is simple, efficient, and easy to scale up. However, PLA suffers from a low number of chain active groups and a low degree of polarization, which affects its tensile strength and triboelectric effect. Summary of the Invention

[0004] This invention provides an amino-reinforced polylactic acid (PLA)-based nanofiber membrane, its preparation method, and its application. It effectively solves the technical problem that the PLA has poor tensile strength and triboelectric effect due to the small number of active groups and low polarization of PLA chains. This invention strengthens the stereocomposite structure of PLA through amino-modified metal-organic framework materials, enhances the electroactivity and gas separation capability of the nanofiber membrane, and enables the fiber membrane to have the characteristics of separating harmful gases, high efficiency, low resistance, and antibacterial properties.

[0005] This invention provides a method for preparing an amino-reinforced polylactic acid-based nanofiber membrane, comprising the following steps:

[0006] Using polylactic acid (PLA) and polylactic acid (PLA) as raw materials, they are dissolved in solvents to obtain a first spinning solution and a second spinning solution, which are then mixed to obtain a spinning solution.

[0007] Aminated metal-organic framework powder is added to the spinning solution to obtain a blend. The blend is then electrospun to form hydrogen bonds between the amino groups and the polylactic acid chain groups in the spinning solution, resulting in an aminated polylactic acid fiber membrane.

[0008] The amino-reinforced polylactic acid fiber membrane is combined with the electrode membrane to obtain an amino-reinforced polylactic acid-based nanofiber membrane.

[0009] In a preferred embodiment, the mass fraction of the aminated metal-organic framework powder in the aminated polylactic acid fiber membrane is 1% to 10%.

[0010] In a preferred embodiment, the aminated metal-organic framework is NH2-ZIF-8, NH2-UiO-66, or NH2-MIL-101.

[0011] In a preferred embodiment, the molecular weight of the L-polylactic acid is (1-4) × 10⁻⁶. 5 The molecular weight of dextrorotatory polylactic acid is (0.5~2)×10. 5 The mass ratio of dextrorotatory polylactic acid to levorotatory polylactic acid is 1:99 to 99:1.

[0012] In a preferred embodiment, the electrospinning parameters are: output voltage of 25kV to 50kV, spinning temperature of 20℃ to 50℃, and spinning humidity of 20% to 40%.

[0013] In a preferred embodiment, during electrospinning, the consumption rate of the blending solution is 0.1 mL / h to 2 mL / h, and the fiber winding rate is 500 rpm to 5000 rpm.

[0014] In a preferred embodiment, the electrode film is one or two of copper mesh electrode, silver nanowire electrode, and silver mesh electrode.

[0015] In a preferred embodiment, the gap between the aminated polylactic acid fiber membrane and the electrode membrane is 0.1 mm to 0.5 mm.

[0016] In a preferred embodiment, the average fiber diameter of the aminated polylactic acid fiber membrane is 0.01–1.5 μm, and the basis weight of the resulting fiber membrane is 2.0–7.5 g / m³. 2 .

[0017] The second objective of this invention is to provide an amino-reinforced polylactic acid-based nanofiber membrane prepared by the above-described preparation method.

[0018] A third objective of this invention is to provide an application of the above-mentioned amino-reinforced polylactic acid-based nanofiber membrane in air filtration.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention introduces highly active amino groups, providing active sites for hydrogen bond formation. When these amino groups encounter polylactic acid (PLA) chain groups, hydrogen bonds are formed. Therefore, by introducing aminated metal-organic framework materials, this invention significantly increases the hydrogen bond density. This increased density enhances the crystallization rate (crystallization kinetics) of PLA, promoting chain phase change and further facilitating stereocomplexation, resulting in an aminated PLA fiber membrane (MSC-PLA fiber membrane). This membrane provides the basis for a triboelectric nanogenerator. By combining it with an electrode membrane, it can stably collect charges and form a potential field. This invention constructs a triboelectric nanogenerator structure through membrane combination, resulting in an amino-reinforced PLA-based nanofiber membrane with high electroactivity, antimicrobial activity, excellent PMs filtration effect, and low filtration resistance. Furthermore, long-term storage does not affect the filter material potential.

[0021] The amino-reinforced polylactic acid (PLA) membrane prepared by this invention achieves a filtration efficiency of 99.0%–99.99% for PMs, maintains a surface potential of 12–18 kV, reduces breathing resistance to 90–180 Pa, achieves an antiviral efficiency of 99.0%–99.98%, and a bacterial filtration efficiency of 99.2%–99.98%. This invention provides a high-performance air filter membrane with broad application prospects and its preparation method, and it also has a significant positive effect on the triboelectric properties of traditional PLA filter membranes. Attached Figure Description

[0022] Figure 1 This is a process flow diagram for preparing the amino-reinforced polylactic acid-based nanofiber membrane of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0024] The present invention addresses the technical problem mentioned in the background section: the existing polylactic acid (PLA) chains have a small number of active groups and low polarization, resulting in poor tensile strength and triboelectric properties. To address these issues, the present invention provides an amino-reinforced PLA-based nanofiber membrane, its preparation method, and its applications. This invention strengthens the stereocomposite structure of PLA through an amino-modified metal-organic framework material, enhancing the electroactivity and gas separation capability of the nanofiber membrane, thus giving the membrane the characteristics of harmful gas separation, high efficiency, low resistance, and antibacterial properties.

[0025] The technical solution of the present invention will be analyzed and described in detail below.

[0026] This invention first provides a method for preparing an amino-reinforced polylactic acid-based nanofiber membrane, comprising the following steps:

[0027] Using polylactic acid (PLA) and polylactic acid (PLA) as raw materials, they are dissolved in solvents to obtain a first spinning solution and a second spinning solution, which are then mixed to obtain a spinning solution.

[0028] The solvent is at least one of dimethyl carbonate (DMC), N,N dimethylformamide (DMF), dichloromethane, and chloroform.

[0029] Aminated metal-organic framework powder is added to the spinning solution to obtain a blend. The blend is then electrospun to form hydrogen bonds between the amino groups and the polylactic acid chain groups in the spinning solution, resulting in an aminated polylactic acid fiber membrane with an average fiber diameter of 0.01–1.5 μm and a basis weight of 2.0–7.5 g / m³. 2 .

[0030] The amino-reinforced polylactic acid fiber membrane is combined with the electrode membrane to obtain an amino-reinforced polylactic acid-based nanofiber membrane.

[0031] In the above technical solution, an amino-reinforced polylactic acid fiber membrane (MSC-PLA fiber membrane) is obtained by introducing highly active amino groups to increase hydrogen bond density and promote stereocomposite formation. This provides the basis for a triboelectric nanogenerator. By combining it with an electrode membrane, it can stably collect charges and form an electric potential field. By combining the membranes, a triboelectric nanogenerator structure is formed, thereby obtaining an amino-reinforced polylactic acid-based nanofiber membrane with high electroactivity, antimicrobial activity, excellent PMs filtration effect and low filtration resistance. Furthermore, long-term storage will not affect the filter material potential.

[0032] In a preferred embodiment, the mass fraction of the aminated metal-organic framework powder in the aminated polylactic acid fiber membrane is 1% to 10%. The aforementioned limited mass fraction of the aminated metal-organic framework powder is to control the intensity of stereocompositing. Too little L- or D-polylactic acid will not achieve the desired stereocompositing effect, resulting in low stereocompositing strength and adversely affecting the spinning results.

[0033] In a preferred embodiment, the aminated metal-organic framework is NH2-ZIF-8, NH2-UiO-66, or NH2-MIL-101.

[0034] It should be noted that the above-mentioned methods for preparing aminated metal-organic frameworks all involve reacting the aminated precursor solution via sol-gel method, co-precipitation method, or microwave synthesis method. After the reaction is completed, the mixture is washed with deionized water, methanol, or DMF and dried for 12 to 72 hours.

[0035] The precursor solution of the metal-organic framework NH2-UiO-66 is a mixed solution of chromium chloride, diaminoterephthalic acid, and acetic acid.

[0036] The precursor solution of the metal-organic framework NH2-ZIF-8 is a mixed solution of aluminum acetate, dimethylimidazole, 2-aminobenzimidazole, deionized water, and CTAB.

[0037] The precursor solution of the metal-organic framework MIL-101 is a mixed solution of ultrapure water, Fe(NO3)3-9H2O powder, DMF, and 2-aminoterephthalic acid.

[0038] In a preferred embodiment, the molecular weight of the L-polylactic acid is (1-4) × 10⁻⁶. 5 The molecular weight of dextrorotatory polylactic acid is (0.5~2)×10. 5 The mass ratio of dextrorotatory polylactic acid (DPL) to levurorotatory polylactic acid (LPL) is 1:99 to 10:90. Both DPL and LPL have molecular weights greater than 100,000 for the spinning solution to have sufficient viscosity to support the spinning process. The molecular weight range given here represents the range with the best electrospinning effect; values ​​higher or lower than this range will result in poor performance.

[0039] In a preferred embodiment, the electrospinning parameters are as follows: output voltage of 25kV to 50kV, spinning temperature of 20℃ to 50℃, and spinning humidity of 20% to 40%. During electrospinning, the consumption rate of the blending solution is 0.1mL / h to 2mL / h, and the fiber winding rate is 500rpm to 5000rpm. Regarding the above-mentioned fiber winding rate, the winding speed mainly affects the fiber thickness and is a relatively important indicator. Lower speeds result in coarser fibers, while higher speeds result in finer fibers. However, if the speed is too high, the rollers cannot withstand it. Therefore, the above-mentioned electrospinning parameter set was selected in the experimental investigation of this invention.

[0040] In a preferred embodiment, the electrode film is one or two of copper mesh electrode, silver nanowire electrode, and silver mesh electrode.

[0041] To ensure optimal triboelectric effect of the fiber membrane, the gap between the aminated polylactic acid fiber membrane and the electrode membrane is 0.1 mm to 0.5 mm. A small gap between the electrode membrane and the polylactic acid membrane is necessary to achieve the triboelectric effect; if they are completely attached, there is no relative movement and no friction; if the distance is too great, breathing vibrations will prevent the membranes from contacting each other, thus also failing to achieve the triboelectric effect.

[0042] The technical effects of the present invention will be described in detail below through specific embodiments and comparative examples.

[0043] Example 1

[0044] A method for preparing an amino-reinforced polylactic acid-based nanofiber membrane includes the following steps:

[0045] S1. Preparation of spinning solution (MSC-PLA spinning solution): 0.99g of 1×10⁻⁶ molecular weight spinning solution was used. 5 Polylactic acid (PLLA) of L-type and 0.01g of which has a molecular weight of 0.5×10 5 Dextrorotatory polylactic acid (PDLA) was dissolved in 10 mL of a DMF+DMC mixed solution with a volume ratio of 3:7. The PDLA and PLLA solutions were mixed and stirred for 0.5 h until homogeneous, to obtain a spinning solution with a polylactic acid mass concentration of 0.1 g / mL.

[0046] S2. Preparation of aminated metal-organic framework (aminated MOF) powder: The mixed solution of chromium chloride, diaminoterephthalic acid and acetic acid, i.e. UIO-66 aminated precursor solution, was sonicated for 3 min, processed by solution-gel method (PTFE reactor heat preservation time 72 h, washing liquid is deionized water), and dried for 12 h to obtain aminated UIO-66 powder.

[0047] S3. Preparation of Aminated Polylactic Acid Fiber Membrane (MSC-PLA Fiber Membrane): Aminated UIO-66 powder was incorporated into the spinning solution at a mass ratio of 1 wt%. The membrane was prepared using single-needle electrospinning technology (output voltage 25 kV, solution consumption rate 0.1 mL / h, roller speed 500 rpm, spinning temperature 20℃, spinning humidity 40%), yielding fibers with an average diameter of 1.5 μm and a basis weight of 7.5 g / m². 2 MSC-PLA fiber membrane.

[0048] S4. Preparation of amino-reinforced polylactic acid nanofiber membrane: Combine the MSC-PLA fiber membrane obtained in S3 with the electrode membrane in a sandwich structure of "copper mesh electrode membrane - MSC-PLA fiber membrane - silver nanowire electrode membrane" to obtain an amino-reinforced polylactic acid nanofiber membrane.

[0049] Example 2

[0050] A method for preparing an amino-reinforced polylactic acid-based nanofiber membrane includes the following steps:

[0051] S1. Preparation of MSC-PLA spinning solution: 0.01g of MSC-PLA spinning solution with a molecular weight of 4×10 5 PLLA and 0.99g with a molecular weight of 3×10 5 PDLA was dissolved in 33 mL of a DMF+DMC mixed solution with a volume ratio of 3:7. The PDLA and PLLA solutions were mixed and stirred for 2 h until homogeneous, to obtain a spinning solution with a polylactic acid mass concentration of 0.03 g / mL.

[0052] S2. Preparation of amination-modified MOF powder: The mixed solution of chromium chloride, diaminoterephthalic acid and acetic acid, i.e. UIO-66 amination precursor solution, is sonicated for 20 min, processed by co-precipitation method (PTFE reactor heat preservation time 72 h, washing liquid is methanol), and dried for 72 h to obtain amination-modified UIO-66 powder.

[0053] S3. Preparation of MSC-PLA fiber membrane: Aminated UIO-66 powder was incorporated into the spinning solution at a mass ratio of 4 wt%, and the membrane was prepared by single-needle electrospinning technology (output voltage 50 kV, solution consumption rate 2 mL / h, roller speed 5000 rpm, spinning temperature 20℃, spinning humidity 40%) to obtain a fiber with an average diameter of 0.1 μm and a basis weight of 2 g / m². 2 MSC-PLA fiber membrane.

[0054] S4. Preparation of amino-reinforced polylactic acid nanofiber membrane: Combine the MSC-PLA fiber membrane obtained in S3 with the electrode membrane according to the structure of "silver mesh electrode membrane - MSC-PLA fiber filter membrane" to obtain an amino-reinforced polylactic acid nanofiber membrane.

[0055] Example 3

[0056] A method for preparing an amino-reinforced polylactic acid-based nanofiber membrane includes the following steps:

[0057] S1. Preparation of MSC-PLA spinning solution: 2g of MSC-PLA spinning solution with a molecular weight of 4×10 5 PLLA and 2g with a molecular weight of 3×10 5 PDLA was dissolved in 10 mL of a DMF+DMC mixed solution with a volume ratio of 3:7. The PDLA and PLLA solutions were mixed and stirred for 1 h until homogeneous, to obtain a spinning solution with a polylactic acid mass concentration of 0.4 g / mL.

[0058] S2. Preparation of amination-modified MOF powder: The amination-modified MIL-101 precursor solution, namely a mixture of ultrapure water, Fe(NO3)3-9H2O powder, DMF and 2-aminoterephthalic acid, was vigorously stirred and sonicated for 15 min. It was then processed using microwave-assisted synthesis (microwave-assisted synthesis power 60W, temperature 140℃, holding for 10 min, washing liquid was methanol), and dried for 12 h to obtain amination-modified MIL-101 powder.

[0059] S3. Preparation of MSC-PLA fiber membrane: Aminated MIL-101 powder was incorporated into the spinning solution at a mass ratio of 10 wt%, and the membrane was prepared by double-needle electrospinning technology (output voltage 30 kV, solution consumption rate 1 mL / h, roller speed 3000 rpm, spinning temperature 30℃, spinning humidity 60%) to obtain a fiber with an average diameter of 0.9 μm and a basis weight of 6 g / m².2 MSC-PLA fiber membrane.

[0060] S4. Preparation of amino-reinforced polylactic acid nanofiber membrane: Combine the MSC-PLA fiber membrane obtained in S3 with the electrode membrane according to the structure of "copper mesh electrode membrane - MSC-PLA fiber filter membrane - silver mesh electrode membrane" to obtain an amino-reinforced polylactic acid nanofiber membrane.

[0061] Example 4

[0062] A method for preparing an amino-reinforced polylactic acid-based nanofiber membrane includes the following steps:

[0063] S1. Preparation of MSC-PLA spinning solution: 1.5g of MSC-PLA spinning solution with a molecular weight of 2×10 5 PLLA and a molecular weight of 1.5 × 10⁻⁶ per gram. 5 PDLA was dissolved in 10 mL of a DMF+DMC mixed solution with a volume ratio of 3:7. The PDLA and PLLA solutions were mixed and stirred for 0.5 h until homogeneous, to obtain a spinning solution with a polylactic acid mass concentration of 0.25 g / mL.

[0064] S2. Preparation of amination-modified MOF powder: The precursor solution of amination-modified ZIF-8, a mixed solution of aluminum acetate, dimethylimidazole, 2-aminobenzimidazole, deionized water and CTAB, was sonicated for 20 min and processed by microwave-assisted synthesis (microwave-assisted synthesis power 60W, temperature 140℃, holding for 10 min, washing liquid is methanol), and dried for 72 h to obtain amination-modified ZIF-8 powder.

[0065] S3. Preparation of MSC-PLA fiber filter membrane: Aminated ZIF-8 powder was incorporated into the spinning solution at a mass ratio of 6 wt%, and the membrane was prepared by double-needle electrospinning technology (output voltage 40 kV, solution consumption rate 1.5 mL / h, roller speed 1500 rpm, spinning temperature 40℃, spinning humidity 50%) to obtain fibers with an average diameter of 1.2 μm and a basis weight of 5 g / m². 2 MSC-PLA fiber membrane.

[0066] S4. Preparation of amino-reinforced polylactic acid nanofiber membrane: Combine the MSC-PLA fiber membrane obtained in S3 with the electrode membrane according to the structure of "copper mesh electrode membrane - MSC-PLA fiber filter membrane - copper mesh electrode membrane" to obtain an amino-reinforced polylactic acid nanofiber membrane.

[0067] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows:

[0068] Comparative Example 1

[0069] The difference compared to Example 1 is that: instead of using an amino-reinforced polylactic acid nanofiber membrane as the intermediate layer, polylactic acid nonwoven fabric (18 g / m²) is used directly. 2 The filter membrane is obtained by combining it with a silver nanowire electrode membrane in a structure of "silver nanowire electrode membrane - polylactic acid nonwoven fabric - silver nanowire electrode membrane".

[0070] A method for preparing a polylactic acid nonwoven fabric-based nanofiber membrane includes the following steps:

[0071] 18g / m 2 Polylactic acid nonwoven fabric is combined with an electrode membrane in a sandwich structure of "silver nanowire electrode membrane - polylactic acid nonwoven fabric - silver nanowire electrode membrane" to obtain a polylactic acid nonwoven fabric-based nanofiber membrane.

[0072] Comparative Example 2

[0073] Compared with Example 2, the difference is that instead of using an aminated organometallic skeleton as a filler, ordinary UIO-66 powder is used as a filler. A non-amino-reinforced stereocomposite fiber filter membrane is prepared by electrospinning. The copper mesh and SC-PLA fiber membrane are combined in the form of "copper mesh electrode membrane - non-amino-reinforced stereocomposite fiber filter membrane - copper mesh electrode membrane" to obtain the filter membrane.

[0074] A method for preparing a polylactic acid-based nanofiber membrane includes the following steps:

[0075] S1. Preparation of MSC-PLA spinning solution: 0.01g of MSC-PLA spinning solution with a molecular weight of 4×10 5 PLLA and 0.99g with a molecular weight of 3×10 5 PDLA was dissolved in 33 mL of a DMF+DMC mixed solution with a volume ratio of 3:7. The PDLA and PLLA solutions were mixed and stirred for 2 h until homogeneous, to obtain a spinning solution with a polylactic acid mass concentration of 0.03 g / mL.

[0076] S3. Preparation of MSC-PLA fiber membrane: Ordinary UIO-66 powder was incorporated into the spinning solution at a mass ratio of 4 wt%, and the membrane was prepared by single-needle electrospinning technology (output voltage 50 kV, solution consumption rate 2 mL / h, roller speed 5000 rpm, spinning temperature 20℃, spinning humidity 40%) to obtain a fiber with an average diameter of 0.1 μm and a basis weight of 2 g / m². 2 Non-amino-reinforced polylactic acid fiber membrane (SC-PLA fiber membrane).

[0077] S4. Preparation of amino-reinforced polylactic acid-based nanofiber membrane: Combine the SC-PLA fiber membrane obtained in S3 with the electrode membrane according to the structure of "copper mesh electrode membrane - SC-PLA fiber membrane - copper mesh electrode membrane" to obtain a polylactic acid-based nanofiber membrane.

[0078] Comparative Example 3

[0079] Compared with Example 3, the difference is that the filter membrane of the N95 mask (brand name 3M 9132) is used instead of the MSC-PLA fiber membrane for performance testing, and the filter membrane is obtained by combining "copper mesh electrode membrane - N95 filter membrane - copper mesh electrode membrane".

[0080] The properties of the amino-reinforced polylactic acid nanofiber membranes prepared in Examples 1 to 4 and Comparative Examples 1 to 3 of the present invention were characterized and tested, and the results are as follows.

[0081] Structural characterization and performance testing:

[0082] Scanning electron microscopy: The microstructure of polylactic acid fiber membranes and silver nanofiber membranes was observed using a field emission scanning electron microscope (model JSM-7900F, Nippon Electron).

[0083] Dielectric constant test: The dielectric constant was tested using a dielectric constant tester (model Wayne Kerr 6500B, Wayne Kerr, UK).

[0084] Breathing resistance test: Breathing resistance was measured using a micromanometer (AIRPROAP800, TSI Corporation, USA), a humanoid respirator, and a simulated human head. The gas flow rate was set to 85 L / min. The filter membrane was encapsulated on the simulated human head, and the air pressure in the cavity formed by the filter membrane and the human head and the atmospheric pressure were measured and the difference was calculated. The experiment was repeated three times and the average value was taken to calculate the breathing resistance of the filter membrane.

[0085] Surface potential test: The surface potential of the nanofiber membrane was tested using a non-contact electrostatic meter (VM54XQS, Quatek, USA). The test height was 2 cm, and the temperature and humidity were kept constant at 25℃ and 45%. Twenty data points were randomly collected for each sample and the average value was taken.

[0086] Filtration performance testing: NaCl was selected as the test aerosol (Model 8026 aerosol generator, TSI Corporation, USA). The generated PM particles ranged in size from 10 nm to 10 μm. Four flow rates (10 L / min, 32 L / min, 65 L / min, and 85 L / min) were used to simulate different breathing states of the wearer (resting breathing, normal breathing, rapid breathing, and tachypnea) for filtration performance testing. The fiber membrane was cut into 120 mm diameter discs and then placed in the assembled filter device. Filtration efficiency (Model 3910 Nanoparticle Size Spectrometer (SMPS) and Model 3310 Optical Particle Size Spectrometer (OPS), TSI Corporation, USA) and pressure drop (Model AP800 micromanometer, TSI Corporation, USA) were measured using a self-made PM filtration testing device.

[0087] CO2 Adsorption Test: The gas adsorption isotherm of carbon dioxide (99.999%) was analyzed using a 3Flex 3500 surface characterization analyzer (Micromeritics Instrument Corporation, USA). The low temperature was controlled by a Dewar flask (4L) containing dry ice and acetone. The water bath temperature was controlled by a water bath (Changzhou First Textile Equipment Co., Ltd.). The material was pre-degassed at room temperature for 16 hours before collecting the adsorption isotherm.

[0088] CO adsorption test: The adsorption isotherm of CO (99.996%) was measured using an automated volumetric adsorption analyzer, BELSORP-max (Japan, MicrotracBel), connected to a cryostat system. The sample was placed on a copper plate and evacuated under dynamic vacuum at room temperature for 12 hours to remove guest molecules. The weight of the evacuated sample was measured under inert gas conditions, and it was placed in a cryostat system under high vacuum (pressure below 10) before the experiment. -3 The sample was evacuated in situ for 2 hours at a pressure of 1000 Pa, and then CO gas was introduced into the sample under controlled temperature. The degree of adsorption was determined by the decrease in the pressure of the gas introduced at equilibrium.

[0089] Table 1. Test results of breathing resistance, surface potential, and filtration performance of the amino-reinforced polylactic acid nanofiber membrane of the present invention.

[0090]

[0091]

[0092] Table 2. Antiviral test results of amino-reinforced polylactic acid nanofiber membranes

[0093]

[0094] Table 3. Microbial inactivation test results of amino-reinforced polylactic acid nanofiber membranes

[0095]

[0096] Table 4. Gas separation test results of amino-reinforced polylactic acid nanofiber membranes (298K)

[0097]

[0098] The surface potential, filtration efficiency, breathing resistance, tensile strength, antiviral activity, antibacterial activity, and filtration efficiency of the amino-reinforced polylactic acid nanofiber membrane prepared according to this invention were tested. The results are shown in Tables 1 to 4. The amino-reinforced polylactic acid nanofiber membrane of this invention has a filtration efficiency of 99.0% to 99.99% for PMs, a surface potential maintained at 12kV to 18kV, a breathing resistance of 90Pa to 180Pa, an antiviral efficiency of 99.0% to 99.98%, and a bacterial filtration efficiency of 99.2% to 99.98%.

[0099] The experiment included four sets of exemplary embodiments and three sets of comparative embodiments. The results showed that increasing the content of amination-modified MOF effectively increased the triboelectricity and charge retention capacity of the filter membrane, enhancing its ability to filter CO2 and successfully separating CO from CO2. However, the maximum addition amount was 10 wt%, which maintained the surface potential at approximately 18 kV with minimal change in charge over 30 days. Changing the ratio of PDLA to PLLA within the range of 1:99 to 99:1 had little impact on the results. While the silver nanowire electrode membrane exhibited the best antibacterial performance, considering cost, the combination of copper mesh electrode membrane and silver nanowire electrode membrane offered the highest cost-effectiveness. The filter membrane prepared according to this invention could maintain a bacterial filtration efficiency of 99.0% to 99.98% and an antiviral efficiency of 99.0% to 99.98%. Therefore, the altered experimental conditions in the four sets of embodiments did not significantly affect the experimental results, indicating that the experiment was feasible.

[0100] In three comparative studies, experiments were conducted using self-purchased polylactic acid (PLA) nonwoven fabric instead of amino-reinforced PLA stereocomposite self-powered fiber filter membranes, non-amino-reinforced PLA stereocomposite self-powered fiber filter membranes instead of amino-reinforced PLA stereocomposite self-powered fiber filter membranes, and electret filter membranes from N95 masks instead of high-porosity SC-PLA fiber membranes. The results showed that the purchased PLA nonwoven fabric could not achieve the same triboelectric effect as the electrospun high-porosity SC-PLA fiber membrane. This significantly affected its ability to maintain surface potential over a long period, filter and inactivate microorganisms, and adsorb and capture PMs, and also significantly increased breathing resistance. The present invention proposes requirements for low filtration resistance, microbial inactivation, and long-lasting effect. However, without using MOF as a filler, the need for a large number of hydrogen bonds to promote stereocomplexity cannot be met, which would significantly reduce the electroactivity of the fiber filter membrane and the PMs filtration efficiency. Replacing the high-porosity SC-PLA fiber membrane with an electret filter membrane from an N95 mask would greatly increase the membrane's breathing resistance. If put into production, it might cause significant discomfort to the human body, and its filtration and inactivation of viruses are very poor. Except for samples where only aminated MIL-101 is used to replace the electrodes, the comparative sample shows very poor gas separation performance, failing to meet the requirements of low filtration resistance, microbial inactivation, and effective gas separation proposed in this invention.

[0101] Based on comprehensive observations of the examples and comparative examples, the amino-reinforced polylactic acid stereocomposite self-powered fiber filter membrane, compared with the traditional polylactic acid filter membrane, shows a significant improvement in filtration efficiency for PMs and bacteria, as well as in virus inactivation ability. It also exhibits a significant increase in the surface potential of the filter membrane and a significant decrease in breathing resistance. Therefore, the experimental method proposed in this invention is feasible, the produced product meets expectations, and the materials used are reasonable. Thus, this invention provides a high-performance air filter membrane with broad application prospects.

[0102] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing an amino-reinforced polylactic acid-based nanofiber membrane, characterized in that, Includes the following steps: Using polylactic acid (PLA) and polylactic acid (PLA) as raw materials, they are dissolved in solvents to obtain a first spinning solution and a second spinning solution. The first spinning solution and the second spinning solution are then mixed to obtain a spinning solution. Aminated metal-organic framework powder is added to the spinning solution to obtain a blend. The blend is then electrospun to form hydrogen bonds between the amino groups and the polylactic acid chain groups in the spinning solution, resulting in an aminated polylactic acid fiber membrane. The mass fraction of the aminated metal-organic framework powder in the aminated polylactic acid fiber membrane is 1% to 10%. The aminated metal-organic framework is NH2-ZIF-8, NH2-UiO-66, or NH2-MIL-101. The aminated polylactic acid fiber membrane is combined with the electrode membrane to obtain an amino-reinforced polylactic acid-based nanofiber membrane; the gap between the aminated polylactic acid fiber membrane and the electrode membrane is 0.1 mm to 0.5 mm; the electrode membrane is one or two of copper mesh electrode membrane, silver nanowire electrode membrane, and silver mesh electrode membrane.

2. The preparation method according to claim 1, characterized in that, The parameters for electrospinning are: output voltage of 25kV~50kV, spinning temperature of 20℃~50℃, and spinning humidity of 20%~40%; the consumption rate of the blending solution is 0.1mL / h~2mL / h.

3. The preparation method according to claim 1, characterized in that, The molecular weight of the L-polylactic acid is (1~4)×10 5 The molecular weight of dextrorotatory polylactic acid is (0.5~2)×10. 5 The mass ratio of dextrorotatory polylactic acid to levorotatory polylactic acid is 1:99~99:

1.

4. The preparation method according to claim 1, characterized in that, The average fiber diameter of the aminated polylactic acid (PLA) fiber membrane is 0.01~1.5 μm, and the basis weight of the aminated PLA fiber membrane is 2.0~7.5 g / m³. 2 .

5. An amino-reinforced polylactic acid-based nanofiber membrane prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the amino-reinforced polylactic acid nanofiber membrane according to claim 5 in air filtration.

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