Preparation method of biodegradable high-performance polylactic acid multi-scale fiber membrane

Abstract

The application discloses a preparation method of biodegradable high-performance polylactic acid multi-scale fiber membrane, and specifically comprises the following steps: preparing polyquaternary ammonium salt-10 by adding isopropanol as a solvent, ETA solution and hydroxyethyl cellulose into isopropanol for reaction; preparing a precursor solution by dissolving the polyquaternary ammonium salt-10 and polylactic acid particles in 2,2,2-trifluoroethanol; the introduction of the polyquaternary ammonium salt-10 improves the conductivity and viscosity of the solution, enhances the electric field force suffered under the high-voltage electrostatic field of the jet flow and promotes the instability of the charged jet flow in the electrostatic spinning, so that the jet flow is split to form extremely fine fibers; and the polylactic acid multi-scale fiber membrane with superfine nanofibers and submicron fibers is prepared by one-step method. Compared with the existing preparation process, the application has the advantages of simple process, easy operation, high production efficiency, excellent filtering performance and filtering stability of the prepared polylactic acid multi-scale fiber membrane to fine particles of different particle sizes and even the most penetrating PM 0.3 and excellent light transmittance, and is fully biodegradable and green and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the technical field of biodegradable high-performance fiber air filtration materials, specifically relating to a method for preparing a biodegradable high-performance polylactic acid multiscale fiber membrane. Background Technology

[0002] Air pollution such as fine particulate matter (PM) and the spread of infectious viruses have become major culprits threatening human life and health. (Distinct from PM) 2.5 PM5, PM 10 Other fine particulate matter types, PM 0.3 The maximum penetrating particle size (MPPS) is approximately 300 nm, with a diffusion distance exceeding tens of kilometers. It remains suspended in the atmosphere for extended periods, making it extremely difficult to intercept. MPPS carrying toxic substances and deadly viruses... 0.3 It can easily penetrate deep into the lungs through the human respiratory system and cause infection, so there is an urgent need to develop high-performance personal protective materials.

[0003] Currently, microporous electret meltblown nonwoven fabrics composed of ultrafine fibers (1-5μm), produced using meltblown spinning technology, are widely used as the core filter layer of masks. As the most common commercial respirators in daily life, N95, KN95, and surgical masks can filter over 95% and 90% of MPPS PM through the synergistic effect of electrostatic attraction and physical interception, respectively. 0.3 However, existing meltblown filters are made from non-degradable petroleum-derived polypropylene (PP). The large-scale disposal of disposable polypropylene masks generates substantial amounts of harmful microplastics, causing serious damage to soil, water, and other environmental environments. Compared to meltblown spinning, electrospinning is considered one of the most promising technologies for preparing uniform submicron fibers (100–1000 nm). Electrospun fiber membranes possess advantages such as small pore size, large specific surface area, and high porosity, which are crucial for the efficient filtration of PM2.5. 0.3 This created the necessary prerequisites. Due to the submicron diameter of electrospun fibers, in order to efficiently intercept PM... 0.3 Further reduction in pore size and diameter is necessary, which inevitably increases the pressure drop and packing density of the fiber membrane, making it difficult to balance filtration efficiency and pressure drop. Therefore, the development of biodegradable, high-performance protective filters is particularly important and urgent. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a biodegradable polylactic acid (PLA) fiber air filter material with a multi-scale fiber structure for high-performance filtration. Specifically, a cationic polyelectrolyte, polyquaternium-10, is used to regulate the physicochemical properties of the PLA spinning solution. The addition of polyquaternium-10 significantly improves the conductivity and viscosity of the spinning solution. Electrospinning technology further refines the fiber diameter and induces unstable oscillations in the charged jet, thereby generating a multi-scale fiber structure. The small pore size resulting from the multi-scale fiber structure design enables the fiber membrane to effectively capture PM2.5. 0.3 This invention reduces the packing density of the fiber membrane, thereby lowering the resistance to airflow. The polylactic acid multi-scale fiber membrane prepared in one step using electrospinning technology solves the problem of balancing filtration efficiency and pressure drop in electrospun fibers. It also exhibits superior filtration stability, biodegradability, and high light transmittance, making it widely applicable in air filtration fields such as transparent personal protective masks and anti-smog window screens, demonstrating significant practical value.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a biodegradable, high-performance polylactic acid multiscale fiber membrane, comprising the following specific steps:

[0007] (1) The cationic etherifying agent ETA solution was reacted with hydroxyethyl cellulose in isopropanol to prepare polyquaternary ammonium salt-10;

[0008] (2) Dissolve polyquaternium-10 and polylactic acid particles in 2,2,2-trifluoroethanol and stir until homogeneous to obtain polylactic acid spinning solution.

[0009] (3) The polylactic acid spinning solution was placed in a syringe and electrospinned to prepare a biodegradable high-performance polylactic acid multiscale fiber membrane.

[0010] Furthermore, in step (1) above, the cationic etherifying agent ETA solution is composed of cationic etherifying agent ETA and deionized water in a mass ratio of 1:1.5.

[0011] Furthermore, in step (1) above, the final concentration ratio of the cationic etherifying agent ETA to hydroxyethyl cellulose is 7:13.

[0012] Furthermore, in step (2) above, the final concentration of polyquaternium-10 in the polylactic acid spinning solution is 0 wt% to 1.0 wt%.

[0013] Furthermore, in step (2) above, the final concentration of polylactic acid particles in the polylactic acid spinning solution is 6wt% to 10wt%.

[0014] Furthermore, in step (3) above, the process parameters for electrospinning are: liquid injection speed 0.2-0.5 ml / h, roller speed 200 rpm, receiving distance 12-15 cm, applied voltage 18-24 kV, spinning time 10-40 min, ambient temperature 20-30 ℃, and ambient humidity 40-60% RH.

[0015] Furthermore, in step (3) above, the biodegradable high-performance polylactic acid multiscale fiber membrane has fine fibers and coarse fibers. The fine fibers are nanoscale fibers with a fiber diameter of 25 to 100 nm, and the coarse fibers are submicron-scale fibers with a fiber diameter of 110 to 240 nm.

[0016] Furthermore, in step (3) above, the thickness range of the biodegradable high-performance polylactic acid multiscale fiber membrane is 300–600 nm.

[0017] Application of a biodegradable, high-performance polylactic acid multiscale fiber membrane prepared by the above method in air filtration.

[0018] The polyquaternary ammonium salt-10 prepared in this invention can regulate the physicochemical properties of polylactic acid spinning solution. Biodegradable polylactic acid multi-scale fiber membranes are prepared by electrospinning technology. The multi-scale fiber structure gives the fiber membrane high filtration efficiency, low pressure drop and excellent filtration stability. The ultra-thin thickness of the ultrafine nanofibers in the multi-scale fibers also gives the fiber membrane excellent light transmittance.

[0019] The advantages of this invention are:

[0020] (1) The present invention uses electrospinning technology to prepare biodegradable polylactic acid multiscale fiber membranes in one step. The preparation process is simple, convenient and efficient.

[0021] (2) The polylactic acid multiscale fiber membrane prepared in this invention has high filtration efficiency for PM2.5. 0.3 With a filtration efficiency of over 99.9% and a pressure drop of less than 65Pa, the multi-scale fiber structure design allows the fiber membrane to effectively capture fine particulate matter through physical interception alone, and it has excellent filtration stability in complex environments such as high humidity environments.

[0022] (3) The ultra-thin thickness of the polylactic acid multiscale fiber membrane prepared by the present invention due to the ultra-fine nanofibers gives the fiber membrane excellent light transmittance.

[0023] (4) The polylactic acid multiscale fiber membrane prepared by the present invention can be applied to the field of air filtration, such as transparent personal protective face shields and anti-smog window screens. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0025] Figure 1 A scanning electron microscope image of the fiber membrane of Example 1 is shown.

[0026] Figure 2 A scanning electron microscope image of the fiber membrane in Comparative Example 1 is shown.

[0027] Figure 3 The filtration performance graphs of the fiber membranes of Example 1 and Comparative Example 1 are shown. PLA is the fiber membrane of Comparative Example 1. M-PLA is the fiber membrane of Example 1.

[0028] Figure 4 The filtration efficiency, pressure drop, and quality factor of the fiber membrane of Example 1, Comparative Example 2, and Comparative Example 3 at different wind velocities are shown.

[0029] Figure 5 The graph shows the changes in filtration efficiency of the fiber membrane of Example 1 and Comparative Example 3 before and after treatment in a high humidity environment.

[0030] Figure 6 Optical images of the fiber membrane of Example 1 and Comparative Example 4 at different degradation times under enzymatic hydrolysis experimental conditions are shown. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0032] This invention provides a method for preparing a biodegradable, high-performance polylactic acid multiscale fiber membrane, comprising the following steps:

[0033] (1) Preparation of polyquaternium-10

[0034] In one embodiment, this step can be specifically performed as follows: 2,3-epoxypropyltrimethylammonium chloride (ETA) and deionized water are mixed at a mass ratio of 1:1.5 and stirred evenly at room temperature to form a cationic etherifying agent ETA solution; the cationic etherifying agent ETA solution and hydroxyethyl cellulose are added to the solvent isopropanol and thoroughly mixed at room temperature to obtain a mixed solution. The final concentration of ETA in the mixed solution is 7 wt%, and the final concentration of hydroxyethyl cellulose in the mixed solution is 13 wt%. The pH of the mixed solution is adjusted to 10 with 1M sodium hydroxide solution and then transferred to a reaction vessel. The reaction is carried out at 75°C for 90 minutes, then cooled to room temperature, and then centrifuged at 10,000 rpm for solid-liquid separation. The obtained solid product is washed twice with 95% isopropanol, dried at 120°C for 6 hours, and then ground to obtain polyquaternium-10.

[0035] (2) Preparation of electrospinning precursor solution

[0036] In one embodiment, this step can be specifically performed as follows: polyquaternium-10 and polylactic acid particles (weight average molecular weight of 110,000 and particle size of 3 mm) are added to 2,2,2-trifluoroethanol and magnetically stirred at room temperature until completely dissolved to obtain a precursor solution (also known as polylactic acid spinning solution). The final concentration of polyquaternium-10 in the precursor solution is 1.0 wt%, and the final concentration of polylactic acid in the precursor solution is 8 wt%.

[0037] (3) Preparation of polylactic acid multiscale fiber membrane

[0038] In one embodiment, this step can be specifically performed as follows: the precursor solution is transferred to a syringe for electrospinning, with the injection speed set to 0.2-0.6 ml / h, the roller speed to 200 rpm, the receiving distance to 12 cm, the applied voltage to 18-24 kV, the spinning time to 10-40 min, the ambient temperature to 20-30 °C, and the ambient humidity to 40-60% RH, to prepare a biodegradable high-performance polylactic acid multiscale fiber membrane.

[0039] The specific operation method of the filtration experiment in this invention is as follows:

[0040] The filtration efficiency and pressure drop of the fiber membrane and control sample were tested using the LZC-K1 type filter media comprehensive performance testing platform. The test air velocity was 32 L / min. -1 The aerosol generator produces approximately 125,000 salt particles with a diameter of about 300 nm.

[0041] The specific operation method for the practical applicability test in this invention is as follows:

[0042] The filtration efficiency and pressure drop of fiber membranes and control samples under different low and high wind velocities were tested using the LZC-K1 type filter media comprehensive performance testing platform to evaluate the actual applicability of fiber membranes.

[0043] The specific operation method for the filtration stability test under high humidity conditions in this invention is as follows:

[0044] The fiber membrane and control sample were placed in a constant temperature and humidity chamber, with the temperature set at 25℃ and the humidity at 90%RH. After 48 hours in the chamber, they were removed and the changes in filtration efficiency and pressure drop before and after fiber membrane treatment were tested using the LZC-K1 type filter media comprehensive performance testing platform.

[0045] The specific operation method of the degradation experiment in this invention is as follows:

[0046] Cut the fiber membrane and control sample into 5×5cm squares and place them in a solution with a concentration of 0.4 mg / ml. -1 The sample was taken out of the enzyme solution at regular intervals, and the impurities on the sample surface were washed away with deionized water. The sample was dried at 60°C in a forced-air drying oven until constant weight. The appearance changes of the sample were recorded, the sample mass was weighed and recorded over time, and the weight loss rate of the sample was calculated to evaluate its degradation weight loss.

[0047] Example 1: Preparation of biodegradable high-performance polylactic acid multiscale fiber membrane

[0048] S1: The cationic etherifying agent 2,3-epoxypropyltrimethylammonium chloride (ETA) and deionized water were mixed at a mass ratio of 1:1.5 and stirred evenly at room temperature to form a cationic etherifying agent ETA solution. The cationic etherifying agent ETA solution and hydroxyethyl cellulose were added to the solvent isopropanol and mixed thoroughly at room temperature to obtain a mixed solution. The final concentration of ETA in the mixed solution was 7 wt%, and the final concentration of hydroxyethyl cellulose in the mixed solution was 13 wt%. The pH of the mixed solution was adjusted to 10 with 1M sodium hydroxide solution and then transferred to a reaction vessel. The reaction was carried out at 75°C for 90 minutes, and then cooled to room temperature. The solid-liquid separation was performed by centrifugation at 10,000 rpm. The obtained solid product was washed twice with 95% isopropanol and then dried at 120°C for 6 hours before being ground to obtain polyquaternium-10.

[0049] S2: Weigh 0.05g of polyquaternium-10 into a small glass bottle, add 4.6g of organic solvent 2,2,2-trifluoroethanol, and stir magnetically at room temperature until fully dissolved. Then add 0.4g of polylactic acid particles (weight average molecular weight of 110,000 and particle size of 3mm), and stir magnetically at room temperature until completely dissolved to form a precursor solution (also known as polylactic acid spinning solution).

[0050] S3: Inject the precursor solution into a 10mL syringe for electrospinning. Use polylactic acid nonwoven fabric (produced by Wenzhou Yonghong Chemical Fiber Co., Ltd., model 01) as the receiving substrate, install a 20G needle, and set the electrospinning process parameters as follows: voltage 20kV, injection speed 0.4ml / h, receiving distance 12cm, roller speed 200rpm, ambient temperature 20~30℃, ambient humidity 40~60%RH, and spinning time 30min. Finally, a polylactic acid multiscale fiber membrane with a thickness of 395nm is formed on the surface of the polylactic acid nonwoven fabric substrate.

[0051] from Figure 1The polylactic acid (PLA) multi-scale fiber membrane exhibits no beaded fibers and displays a distribution of both coarse and fine fiber scales. The fine fibers have a diameter in the nanometer range with an average diameter of 46 nm, while the coarse fibers have a diameter in the submicrometer range with an average diameter of 134 nm. Filtration performance measurements show that this PLA multi-scale fiber membrane effectively filters PM2.5. 0.3 The filtration efficiency reaches over 99.97%, with a pressure drop of only 62 Pa. It maintains high filtration efficiency even at high wind speeds and retains excellent filtration performance even in high humidity environments. Degradation experiments show that this polylactic acid multiscale fiber membrane can be completely degraded within 36 hours, demonstrating superior biodegradability.

[0052] Comparative Example 1: Preparation of Polylactic Acid Fiber Membrane

[0053] S1: Weigh 0.4g of polylactic acid particles (weight average molecular weight of 110,000 and particle size of 3mm) into a small glass bottle, add 4.6g of organic solvent 2,2,2-trifluoroethanol, and stir magnetically at room temperature until fully dissolved to obtain PLA spinning solution.

[0054] S2: Inject PLA spinning solution into a 10mL syringe for electrospinning. Use polylactic acid nonwoven fabric (produced by Wenzhou Yonghong Chemical Fiber Co., Ltd., model 01) as the receiving substrate, install a 20G needle, and set the electrospinning process parameters as follows: voltage 10.5kV, injection speed 2.0ml / h, receiving distance 12cm, roller speed 200rpm, ambient temperature 20~30℃, ambient humidity 40~60%RH, and spinning time 30min. Finally, a polylactic acid fiber film is formed on the surface of the polylactic acid nonwoven fabric substrate.

[0055] from Figure 2 Beaded fibers were observed in the polylactic acid (PLA) cellulose membrane. The fiber diameter distribution was relatively uniform, with submicron-level diameters and an average fiber diameter of 224 nm. Filtration performance tests showed that this PLA cellulose membrane effectively filtered PM2.5. 0.3 Its filtration efficiency is only around 61%, which is insufficient to effectively capture PM2.5. 0.3 .

[0056] Comparative Example 2:

[0057] Commercial N95 mask fiber filter layer's performance on PM2.5 in filtration tests under different wind speeds. 0.3 The filtration efficiency of the N95 mask decreased to some extent, from 99.98% to 98.8%, and the filter layer material of the N95 mask is non-degradable polypropylene.

[0058] Comparative Example 3:

[0059] Commercial medical surgical masks with SM fiber filter layers tested for PM2.5 at different wind speeds. 0.3The filtration efficiency showed a significant decrease, dropping sharply from 98.7% to 84.5%, particularly in high humidity environments, affecting PM2.5. 0.3 The filtration efficiency also decreased significantly, from 96% to 92%, and the filter layer material of the medical surgical mask is also made of non-degradable polypropylene.

[0060] Comparative Example 4:

[0061] Degradation experiments on the fiber filter layer of commercial polylactic acid water electret masks showed that the polylactic acid fiber filter layer of the polylactic acid water electret mask only shrank in morphology and did not change significantly with the extension of degradation time.

Claims

1. A method for preparing biodegradable high-performance polylactic acid multiscale fiber membranes, characterized by: The preparation method comprises the following steps: (1) dissolving cationic etherifying agent 2,3-epoxypropyl trimethyl ammonium chloride solution and hydroxyethyl cellulose in isopropyl alcohol to prepare polyquaternary ammonium salt-10; (2) dissolving polyquaternary ammonium salt-10 and polylactic acid particles in 2,2,2-trifluoroethanol to obtain polylactic acid spinning solution; (3) placing the polylactic acid spinning solution in a needle syringe to perform electrospinning to prepare biodegradable high-performance polylactic acid multi-scale fiber membrane; the biodegradable high-performance polylactic acid multi-scale fiber membrane has fine fibers and coarse fibers; the fine fibers are nanofibers with a fiber diameter of 25-100 nm, and the coarse fibers are submicron fibers with a fiber diameter of 110-240 nm.

2. The method for preparing a biodegradable high-performance polylactic acid multiscale fiber membrane according to claim 1, characterized in that: In step (1), the cationic etherifying agent 2,3-epoxypropyl trimethyl ammonium chloride solution is composed of cationic etherifying agent 2,3-epoxypropyl trimethyl ammonium chloride and deionized water at a mass ratio of 1:1.

5.

3. The method for preparing a biodegradable high-performance polylactic acid multiscale fiber membrane according to claim 1, characterized in that: In step (1), the final concentration ratio of the cationic etherifying agent 2,3-epoxypropyl trimethyl ammonium chloride and the hydroxyethyl cellulose is 7:

13.

4. The process for the preparation of biodegradable high performance polylactic acid multiscale fibrous membranes according to claim 1, characterized in that: In step (2), the final concentration of the polyquaternary ammonium salt-10 in the polylactic acid spinning solution is 1.0 wt%.

5. The method for preparing a biodegradable high-performance polylactic acid multiscale fiber membrane according to claim 1, characterized in that: In step (2), the final concentration of the polylactic acid particles in the polylactic acid spinning solution is 6 wt%-10 wt%.

6. The method of making biodegradable high performance polylactic acid multiscale fiber membranes according to claim 1, characterized in that: In step (3), the process parameters of electrospinning are as follows: injection speed 0.2-0.5 ml / h, roller speed 200 rpm, receiving distance 12-15 cm, applied voltage 18-24 kV, spinning time 10-40 min, environmental temperature 20-30℃, and environmental humidity 40-60% RH.

7. The method for preparing a biodegradable high-performance polylactic acid multiscale fiber membrane according to claim 1, characterized in that: In step (3), the thickness of the biodegradable high-performance polylactic acid multi-scale fiber membrane ranges from 300 nm to 600 nm.

8. Application of the biodegradable high-performance polylactic acid multi-scale fiber membrane prepared by the preparation method of any one of claims 1-7 in air filtration.

Images