阅读说明：本技术 一种高透抗菌聚酰亚胺/壳聚糖复合纳米纤维空气过滤膜的制备方法及其产品和应用 (Preparation method of high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane, product and application thereof ) 是由 张兴双 李钰 梁秀 许冠辰 王丹 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种高透抗菌聚酰亚胺/壳聚糖复合纳米纤维空气过滤膜的制备方法及其产品和应用,属于新材料技术领域；包括以下步骤：以聚酰胺酸作为前驱体溶液进行静电纺丝,经热亚胺化形成聚酰亚胺纳米纤维膜,再次通过静电纺丝在聚酰亚胺纳米纤维膜表面负载一层壳聚糖复合纳米纤维,所述壳聚糖复合纳米纤维所用的壳聚糖是经过酶降解的改性壳聚糖；本发明在引入抗菌性的同时提升过滤性能,并且降低了聚氧化乙烯的使用量,提高了该空气过滤膜的抗菌性能。(The invention discloses a preparation method of a high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane, and a product and application thereof, belonging to the technical field of new materials; the method comprises the following steps: performing electrostatic spinning by using polyamic acid as a precursor solution, performing thermal imidization to form a polyimide nanofiber membrane, and loading a layer of chitosan composite nanofiber on the surface of the polyimide nanofiber membrane through electrostatic spinning again, wherein chitosan used by the chitosan composite nanofiber is modified chitosan subjected to enzymatic degradation; the antibacterial air filtering membrane disclosed by the invention has the advantages that the antibacterial property is introduced, the filtering performance is improved, the using amount of polyethylene oxide is reduced, and the antibacterial performance of the air filtering membrane is improved.)

1. A preparation method of a high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane is characterized by comprising the following steps: the preparation method comprises the steps of carrying out electrostatic spinning by using polyamic acid as a precursor solution, forming a polyimide nanofiber membrane through thermal imidization, and loading a layer of chitosan composite nanofiber on the surface of the polyimide nanofiber membrane through electrostatic spinning again, wherein chitosan used by the chitosan composite nanofiber is modified chitosan subjected to enzymatic degradation.

2. The method for preparing the modified chitosan according to claim 1, wherein the re-electrospinning process is co-spinning of the modified chitosan with polyethylene oxide.

3. The production method according to claim 2, wherein the mass ratio of the modified chitosan to the polyethylene oxide is 8: 3.

4. The method according to claim 1, wherein the enzyme used for the enzymatic degradation is at least one of papain, cellulase, lysozyme and pepsin.

5. The preparation method of claim 1, wherein the enzyme used for enzyme degradation is a complex enzyme consisting of cellulase and lysozyme according to a mass ratio of 1: 1.

6. The method of claim 2, wherein the re-electrospun dope further comprises dimethyl sulfoxide and Triton X-100 TM.

7. The method according to claim 5, wherein the enzymatic degradation process parameters are: the temperature is 40 ℃, the time is 2h, the mass ratio of enzyme substrates is 1:10, and the pH is 7.0.

8. A high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane prepared according to the preparation method of any one of claims 1-7.

9. The use of the highly permeable antibacterial polyimide/chitosan composite nanofiber air filtration membrane as claimed in claim 8 in bacteriostatic materials.

10. The use of claim 9, wherein the high permeability antibacterial polyimide/chitosan composite nanofiber air filtration membrane is supported on a window screen metal grid.

Technical Field

The invention relates to the field of new materials, in particular to a preparation method of a high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane, and a product and application thereof.

Background

In recent years, the removal of pollutant particles from the atmosphere has become increasingly important due to the serious pollution problems of the atmosphere. The particulate pollution includes dust, smoke, etc., in which PM is contained_0.3、PM_2.5、PM₁₀And the like, are the most harmful to inhalable particles. The PM particles are small in size, carry a large amount of bacteria and viruses, enter a human body circulation system along with respiration, and are in an environment with poor air quality for a long time in daily work and life, so that the health of people is greatly influenced.

In order to ensure the health of human bodies and provide a clean and comfortable working and living environment, the preparation of the material which has high-efficiency filtration and antibacterial performance is very important. With the improvement of the quality of life and the development of science and technology of people, the requirement of the market on the filtering material is greatly improved, and the air filtering material is required to optimize the environment in the pharmaceutical engineering industry, the food safety industry, the building industry or the automobile industry.

Polyimide (PI) is a polymer of imide monomers, having good chemical resistance, excellent mechanical properties, outstanding optical transparency and excellent thermal stability at high temperatures. Meanwhile, the characteristic of high dipole moment (6.2D) provides a large number of adsorption sites for the adsorption of PM particles. Since the application of polyimide as an air filter material, researchers have proposed various modification methods to improve the filtration efficiency thereof. As a natural high molecular compound, the chitosan has the advantages of low price, good biocompatibility, excellent antibacterial performance and the like. Studies have shown that Chitosan (CTS) has functional groups that make it useful for enhancing filtration performance, but chitosan has poor spinnability and requires the introduction of other materials for co-spinning. Polyethylene oxide (PEO), which is soluble in aqueous solutions and has the properties of polysaccharides as a biocompatible polymer, has a linear structure and can form hydrogen bonds with other polymers, is commonly used for electrospinning ultrafine fibers. And thus is often used to improve the spinnability of chitosan. However, polyethylene oxide is often added at higher ratios (e.g., a PEO/CTS mass ratio of 7:3) to increase jet flow differentiation, thereby reducing fiber diameter and achieving uniform distribution of the components. The higher addition proportion of the polyoxyethylene leads to the reduction of the effective content of the chitosan in the air filter material, thereby influencing the bacteriostatic performance of the material.

Disclosure of Invention

The invention aims to provide a preparation method of a high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane, a product and an application thereof.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a preparation method of a high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane, which comprises the following steps: the preparation method comprises the steps of carrying out electrostatic spinning by using polyamic acid as a precursor solution, forming a polyimide nanofiber membrane through thermal imidization, and loading a layer of chitosan composite nanofiber on the surface of the polyimide nanofiber membrane through electrostatic spinning again, wherein chitosan used by the chitosan composite nanofiber is modified chitosan subjected to enzymatic degradation.

Further, the process of the secondary electrospinning is that the modified chitosan is co-spun with polyethylene oxide.

Further, the mass ratio of the chitosan to the polyethylene oxide is 8: 3.

Further, the enzyme used for the enzymatic degradation is at least one of papain, cellulase, lysozyme and pepsin.

Further, the enzyme used for enzyme degradation is a complex enzyme consisting of cellulase and lysozyme according to the mass ratio of 1: 1.

Further, the re-electrospinning dope further comprises dimethyl sulfoxide and Triton X-100 TM.

Further, the technological parameters of the enzymatic degradation are as follows: the temperature is 40 ℃, the time is 2h, the mass ratio of enzyme substrates is 1:10, and the pH is 7.0.

The invention also provides the high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane prepared by the preparation method.

The invention also provides an application of the high-permeability antibacterial polyimide/chitosan composite nanofiber air filtering membrane in bacteriostasis.

Further, the high-permeability antibacterial polyimide/chitosan composite nanofiber air filter membrane is loaded on a window screening metal grid.

According to known theory, the antibacterial property of the polyimide/chitosan composite nanofiber membrane is derived from the introduction of chitosan composite nanofibers. The antibacterial property of chitosan composite nanofibers can be attributed to surface charges that permeate cell membranes through electrostatic interactions with bacteria, thereby causing leakage of intracellular components leading to bacterial death. Therefore, the material prepared by the invention patent can kill bacteria and inhibit the propagation of the bacteria.

The research shows that the chitosan with the molecular weight less than 5000kDa can permeate cell membranes, enter microbial cells and combine with substances (mainly protein and nucleic acid) with negative electricity in the cells, so that the normal physiological functions of the cells (such as DNA replication, protein synthesis and the like) are influenced, and the microbial death is caused. The invention uses the chitosan after enzyme degradation, increases the content of micromolecular chitosan, and further improves the antibacterial performance of the air filtering membrane.

The invention discloses the following technical effects:

(1) the polyimide/chitosan composite nanofiber membrane is prepared by an electrostatic spinning method, and the prepared membrane has high light transmittance when being loaded on a window screen metal grid, and can effectively filter PM particles in air and kill bacteria and viruses carried by the PM particles. Therefore, the air purifier can be widely applied to various working environments and can prevent pollution sources in the air from entering a room.

(2) The invention adopts the chitosan modified by enzymatic degradation and polyethylene oxide for co-spinning, greatly reduces the usage amount of polyethylene oxide, improves the effective content of chitosan in the filtering membrane material, and further improves the antibacterial performance of the air filtering membrane.

(3) The invention has the advantages of simple operation, perfect preparation method, low cost, degradability, environmental friendliness, high filtration efficiency and wide application range. Meanwhile, the method is high in practicability and can realize large-scale industrial production.

(4) The preparation method disclosed by the invention can be further popularized to the effective regulation and synthesis of the electro-spinning high-permeability polyimide/chitosan composite nano material, and the light transmittance and the filtration efficiency are regulated and controlled by changing the thickness of the polyimide nanofiber layer. The appearance of the composite fiber and the strength of the antibacterial property of the composite fiber can be regulated and controlled by changing the mass ratio of the modified chitosan to the polyethylene oxide, but the light transmittance of the membrane is not influenced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a scanning electron micrograph of a polyimide/chitosan composite nanofiber membrane, polyimide layer, prepared according to example 1, at 3000 times magnification;

FIG. 2 is a scanning electron micrograph of a polyimide/chitosan composite nanofiber membrane, chitosan layer, prepared according to example 1, at 3000 times magnification;

FIG. 3 shows different transmittance vs. PM of polyimide/chitosan nanocomposite fiber membrane prepared according to example 1_1.0Test results of filtration efficiency.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

(1) Modification of chitosan

Dissolving 2g of chitosan in 100ml of 0.5mol/L acetic acid solution, adjusting the pH value of the solution to 7.0, adjusting the temperature to 40 ℃, adding 0.2g of complex enzyme 1 (cellulase and lysozyme are in a mass ratio of 1:1), carrying out oscillation reaction for 2 hours, and finally carrying out enzyme inactivation treatment on the solution to obtain the modified chitosan solution.

(2) Synthesis of polyimide/chitosan composite nanofiber membrane

36.99g of dimethylacetamide (DMAc) was weighed into a flask, 3.3375g of 4,4' -diaminodiphenyl ether (ODA) and 3.708g of pyromellitic dianhydride (PMDA) were weighed, respectively, and the ODA was put into a three-necked flask. The flask containing the ODA was fixed and the monomer was dissolved completely by mechanical stirring for 15 minutes with a mechanical stirrer. The PMDA was added to the flask in 10 portions, the amount of addition decreased as the number of times increased, and the time interval was about 20 minutes after the added PMDA had completely dissolved. And after the addition is finished, rapidly and mechanically stirring for one hour to ensure that the monomers fully react to generate 16 wt% of polyamic acid precursor solution.

Setting the discharge parameters as follows: the voltage is 20KV, the rotating speed is 100r/min, the temperature is 30 ℃, the humidity is 65%, the material returning speed is 0.0010mm/s, the distance between a needle point and a grid receiving base is 20cm, the needle point swings at the center position, the swing amplitude is 30cm, the swing speed is 0.5mm/s, the electrospinning time is respectively set to be 15 min, 30 min, 45 min, 60 min and 75min so as to prepare different samples, the samples are numbered 1, 2, 3, 4 and 5 in sequence, and the samples are dried in an oven at 120 ℃ for 12 h. And (3) putting the polyimide nano fiber membrane into a muffle furnace, heating the polyimide nano fiber membrane from room temperature to 350 ℃ at the heating rate of 3 ℃/min, preserving the heat at 350 ℃ for 1h, and naturally cooling the polyimide nano fiber membrane to the room temperature to obtain the polyimide nano fiber membrane.

3g of polyethylene oxide was dissolved in 100mL of a 0.5mol/L acetic acid solution, and 80mL of the modified chitosan solution obtained in step (1) was added to 20mL of the solution and mixed well. Then, 1.8g of dimethyl sulfoxide (DMSO) and 0.1g of Triton X-100. TM. were added. The mixed solution was stirred magnetically for 24 hours to ensure complete dissolution. The solution was centrifuged to remove air bubbles before use.

Setting the discharge parameters as follows: the voltage is 20KV, the rotating speed is 50r/min, the temperature is 30 ℃, the humidity is 65%, the material returning speed is 0.0007mm/s, the distance between a needle point and a grid receiving base is 15cm, the needle point swings at the center position, the swing amplitude is 30cm, the swing speed is 0.5mm/s, and the electrospinning time is 90min, so that the polyimide/chitosan composite nanofiber membrane is obtained.

The polyimide/chitosan composite nanofiber membrane prepared in this example was subjected to electron microscope scanning, and the results are shown in fig. 1 and 2.

Effect testing

Filter performance test

The polyimide/chitosan composite nanofiber membrane prepared in example 1 was subjected to a filtration efficiency test. The prepared polyimide/chitosan composite nanofiber membrane is placed in an improved G506 automatic filter material tester to be tested. The instrument emits particles with the diameter of 0.3-10 mu m through an aerosol generator (capable of emitting oily and salt particles), and a high-pressure fan ensures that airflow stably passes through a test filter membrane to simulate pollutant particles in air. And testing pollutant particles before and after air flow filtration by a particle counter to calculate the filtration efficiency. Polyimide/chitosan composite nanofiber membrane pair PM prepared in example 1 at different air flow rates_0.3And PM_0.5The filtration efficiencies of (a) are shown in tables 1 and 2; polyimide/chitosan nanocomposite fiber membrane prepared in example 1 has different transmittance to PM_1.0The results of the filtration efficiency test are shown in FIG. 3.

TABLE 1 polyimide/chitosan composite nanofiber membrane vs PM at different gas flow velocities_0.3Filtration efficiency of

TABLE 2 polyimide/chitosan composite nanofiber membrane vs PM at different air flow rates_0.5Filtration efficiency of

Antibacterial property test

The polyimide nanofiber membrane and the polyimide/chitosan composite nanofiber membrane prepared in example 1 are subjected to an antibacterial property test by a colony counting method, and the number of colonies can show the antibacterial effect of a sample. The antibacterial activity of the polyimide/chitosan composite nanofiber membrane on escherichia coli (A-TCC:8739) and staphylococcus aureus (A-TCC:29213) is researched by adopting a colony counting method. Respectively dispersing the polyimide nanofiber membrane and the polyimide/chitosan composite nanofiber membrane with the same mass in a bacterial solution, and setting the oscillation speed to be 180 r. After incubation at 37 ℃ for 24 hours, the bacterial suspension was spread evenly on sterile agar plates using a sterile film-coating rod. The plate was incubated at 37 ℃ for 24 hours, and the number of colonies was observed to infer its antibacterial activity. As shown in table 3, the antibacterial activity of the filtration membrane loaded with chitosan composite nanofibers was significantly improved. The polyimide nanofiber membrane of the control group showed no bacteriostatic activity in the petri dish full of bacteria, while the polyimide/chitosan membrane showed significant bacteriostatic activity, so that the introduction of chitosan increased the antibacterial activity of the membrane.

TABLE 3

Experimental example 1

The composite enzyme 1 (cellulase and lysozyme in a mass ratio of 1:1) in the example 1 is replaced by papain, cellulase, lysozyme, pepsin and composite enzyme 2 (cellulase and papain in a mass ratio of 1:1), the addition amount of the enzymes is unchanged, and the other operations are the same as the example 1 to prepare the polyimide/chitosan composite nanofiber membrane. And then, performing antibacterial property test and spinnability test, wherein the results are shown in table 4, and it can be seen from table 4 that the chitosan is modified by using the complex enzyme of cellulase and lysozyme, so that the spinnability of electrostatic spinning is the highest, and the prepared polyimide/chitosan composite nanofiber membrane has the highest antibacterial effect.

Spinnability test

The spinnability index of the sample obtained by electrostatic spinning is judged by observing the appearance of the fiber by naked eyes in combination with the sem image, a large amount of filaments are produced, the spinnability with good appearance is better, the better spinnability is represented by plus, the more plus represents the better spinnability, and the non-spinnability is represented by minus.

TABLE 4

Experimental example 2

Aiming at the chitosan modification step (1) of example 1, a four-factor three-level orthogonal test is designed according to table 5, the polyimide/chitosan composite nanofiber membrane is prepared according to the method of example 1, and enzyme modification parameters are optimized by detecting the antibacterial rate of escherichia coli. The optimal process parameters obtained finally are as follows: the temperature is 40 ℃, the time is 2h, the mass ratio of enzyme substrates is 1:10, and the pH is 7.0.

TABLE 5

Comparative example 1

The only difference from example 1 is that chitosan modification was not performed and chitosan was directly co-spun with polyethylene oxide.

When the method of the comparative example is adopted to load a layer of chitosan composite nanofiber on the surface of the polyimide nanofiber membrane through electrostatic spinning, the preventability of the spinning solution is extremely poor, and the spinning is difficult.

Comparative example 2

The only difference from example 1 is that the chitosan modification was not performed, and the mass ratio of chitosan to polyethylene oxide was adjusted to 3: 7.

Comparative example 3

The only difference from example 1 is that the mass ratio of chitosan to polyethylene oxide was adjusted to 3: 7.

The polyimide/chitosan composite nanofiber membranes prepared in comparative examples 2-3 were subjected to antibacterial property tests according to the above effect test methods, and the results are shown in table 6. From Table 6, it can be seen that the amount of polyethylene oxide used can be reduced after the chitosan is modified; in addition, the antibacterial performance of the polyimide/chitosan composite nanofiber membrane obtained by co-spinning unmodified chitosan and polyethylene oxide according to the mass ratio of 3:7 is poor, and the antibacterial performance of the polyimide/chitosan composite nanofiber membrane obtained by co-spinning modified chitosan and polyethylene oxide with the same mass ratio is greatly improved.

TABLE 6

According to the invention, chitosan is modified, and then two layers of composite nanofibers are electrospun on the metal grid window screen to prepare the polyimide/chitosan composite nanofiber composite membrane, so that the use amount of polyethylene oxide is greatly reduced, the effective content of chitosan in the filtering membrane material is improved, and the antibacterial performance of the air filtering membrane is further improved. The prepared membrane has high filtration efficiency and excellent antibacterial property and light transmittance. The invention has lower production cost and wide application, and can intercept pollutants (PM particles, bacteria and the like) in the atmosphere to enter the room when being used as the functional window screening, thereby providing comfortable and healthy living and working environments for people.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.