Composite nanofiber membrane as well as preparation method and application thereof

Abstract

The invention belongs to the field of electrostatic spinning, and relates to a composite nanofiber membrane as well as a preparation method and application thereof. The composite nanofiber membrane comprises an aliphatic-aromatic copolyester fiber and a chitosan fiber, in the composite nanofiber membrane, the content of chitosan fibers is 10-60 wt%. The preparation method comprises the following steps: (1) respectively obtaining an aliphatic-aromatic copolyester solution and a chitosan solution; and (2) respectively spraying the aliphatic-aromatic copolyester solution and the chitosan solution to the same receiver from two nozzles by using a solution electrostatic spinning machine to obtain the composite nanofiber membrane. The composite nanofiber membrane disclosed by the invention is free of solvent residues, and has the characteristics of excellent biodegradability, mechanical property and antibacterial and antiviral properties.

Description

Technical Field

[0001] This invention belongs to the field of electrospinning, specifically relating to a composite nanofiber membrane, its preparation method, and its application. Background Technology

[0002] Currently, petroleum-based polymer materials are widely used globally. However, while providing convenience for human life, they also cause severe pollution to the Earth's environment, making "white pollution" a serious problem that cannot be ignored. According to statistics from the International Energy Agency, in the past five years, more than 60 countries have implemented bans or additional taxes on single-use plastic products. The fundamental reason why traditional plastics cause serious white pollution is their extremely long degradation time. Biodegradable plastics, compared to traditional plastics, have the biggest advantage of a shorter degradation time, which can fundamentally solve this problem.

[0003] In the early stages, biodegradable polyesters did not have a competitive advantage in manufacturing costs compared to general synthetic materials (synthetic fibers, synthetic resins, and synthetic rubber) in terms of cost and material properties. However, with the increasing acceptance of sustainable development concepts, urbanization, economic and social development, and improved living standards, raw material and production costs have decreased significantly, and related processing technologies have developed rapidly. In recent years, biodegradable polyesters have been developing rapidly and are gradually being widely used in "disposable" and medical and health fields.

[0004] Electrospinning is a new fiber-making technology developed based on electrospinning. Its principle involves stretching a solution or polymer droplet under a high-voltage electric field into a fiber through electrostatic attraction, which is then deposited onto a current collector to form a nanofiber membrane. Electrospinning offers advantages such as simple operation, low cost, and high yield for nanofiber membrane preparation. Furthermore, the prepared nanofibers possess extremely high specific surface area and porosity, making them promising for applications in filtration materials, flexible pressure sensors, antibacterial and antiviral materials, and agricultural membrane protection materials.

[0005] Aliphatic-aromatic copolyesters, such as polybutylene terephthalate-co-butylene terephthalate (PBST) and polybutylene terephthalate-co-butylene adipate (PBAT), possess good mechanical properties and biodegradability, making them an important approach to solving the "white pollution" problem caused by plastics. However, the application scope of traditional electrospun nanofiber membranes is generally limited, failing to simultaneously meet the requirements of usability and biodegradability, and lacking antibacterial and antiviral properties, thus restricting their application in "use-and-dispose" and medical / health fields where high antibacterial and antiviral performance is required. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a composite nanofiber membrane and its preparation method. The composite nanofiber membrane of this invention has no solvent residue and has excellent biodegradability, mechanical properties and antibacterial and antiviral properties. Moreover, the composite nanofiber membrane is prepared by solution electrospinning, which has the characteristics of simplicity, high efficiency and good continuity.

[0007] To achieve the above-mentioned objectives of the present invention, a first aspect of the present invention provides a composite nanofiber membrane, the composite nanofiber membrane comprising aliphatic-aromatic copolyester fibers and chitosan fibers;

[0008] The composite nanofiber membrane contains 10-60 wt% chitosan fiber, preferably 25-50 wt%.

[0009] A second aspect of the present invention provides a method for preparing the composite nanofiber membrane, comprising the following steps:

[0010] (1) Obtain aliphatic-aromatic copolyester solution and chitosan solution respectively;

[0011] (2) The aliphatic-aromatic copolyester solution and chitosan solution are sprayed from two nozzles onto the same receiver using a solution electrospinning machine to obtain the composite nanofiber membrane.

[0012] The present invention has the following advantages:

[0013] (1) The composite nanofiber membrane of the present invention has no solvent residue and has excellent biodegradability, mechanical properties and antibacterial and antiviral properties. It can be used to prepare high-efficiency low-resistance filter materials, flexible pressure sensor devices, antibacterial and antiviral materials and other fields.

[0014] (2) The present invention uses solution electrospinning with aliphatic-aromatic copolyester and chitosan as raw materials. It has low preparation cost, good continuity, and is safe and environmentally friendly, making it suitable for industrial production.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0016] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0017] To achieve the above-mentioned objectives of the present invention, a first aspect of the present invention provides a composite nanofiber membrane comprising aliphatic-aromatic copolyester fibers and chitosan fibers; wherein the chitosan fiber content in the composite nanofiber membrane is 10-60 wt%, preferably 25-50 wt%.

[0018] In this invention, chitosan fiber has antibacterial and antiviral properties, and can be well composited with aliphatic-aromatic copolyester fiber to further improve the mechanical properties of aliphatic-aromatic copolyester fiber, thereby obtaining a composite nanofiber membrane material with stable mechanical properties.

[0019] According to the present invention, preferably, the average diameter of the fibers in the composite nanofiber membrane is ≤800nm, and more preferably 50-500nm.

[0020] According to the present invention, preferably, the composite nanofiber membrane further includes functional nanoparticles; the functional nanoparticles are selected from at least one of carbon nanotubes, metal oxide nanoparticles and graphene oxide.

[0021] Preferably, based on the total weight of the composite nanofiber membrane, the content of the functional nanoparticles is 1-6 wt%, more preferably 3-6 wt%.

[0022] According to the present invention, preferably, the aliphatic-aromatic copolyester is polybutylene terephthalate-co-butylene adipate and / or polybutylene terephthalate-co-butylene succinate; the weight-average molecular weight of the aliphatic-aromatic copolyester is ≥80,000, preferably 120,000 to 200,000; the weight-average molecular weight of the chitosan is 40,000 to 400,000, preferably 80,000 to 300,000.

[0023] In this invention, the PBST resin is prepared in the laboratory by means of a two-step esterification reaction and a one-step copolymerization reaction.

[0024] According to the present invention, preferably, the porosity of the nanofiber membrane is 20-90%, the tensile stress of the nanofiber membrane is not less than 200 kPa, and the elongation at break is not less than 18%.

[0025] A second aspect of the present invention provides a method for preparing the composite nanofiber membrane, comprising the following steps:

[0026] (1) Obtain aliphatic-aromatic copolyester solution and chitosan solution respectively;

[0027] (2) The aliphatic-aromatic copolyester solution and chitosan solution are sprayed from two nozzles onto the same receiver using a solution electrospinning machine to obtain the composite nanofiber membrane.

[0028] The nanofibers obtained by this invention have a finer average diameter, resulting in thinner, lighter, and more breathable filter materials.

[0029] According to the present invention, preferably, the solvent of the aliphatic-aromatic copolyester solution is dichloromethane or a mixed solvent containing dichloromethane, and the mass concentration of the aliphatic-aromatic copolyester is 3-15 wt%, preferably 5-12 wt%.

[0030] Preferably, the solvent of the aliphatic-aromatic copolyester solution further contains at least one of trifluoroacetic acid, hexafluoroisopropanol, and N,N-dimethylformamide.

[0031] More preferably, the solvent of the aliphatic-aromatic copolyester solution is selected from at least one of the following: a trifluoroacetic acid-dichloromethane system with a volume ratio of 1:9-5:5, a hexafluoroisopropanol-dichloromethane system with a volume ratio of 2:8-7:3, and an N,N-dimethylformamide-dichloromethane system with a volume ratio of 2:8-4:6.

[0032] In this invention, the solvent used is a low-boiling-point volatile organic solvent that can evaporate completely, so that the final composite fiber membrane has no solvent residue.

[0033] According to the present invention, preferably, the solvent of the chitosan solution is an aqueous acetic acid solution, and the mass concentration of chitosan is 3-15 wt%, preferably 5-10 wt%.

[0034] Preferably, the solvent of the chitosan solution is an aqueous solution of acetic acid with a mass concentration of 70-90 wt%.

[0035] According to the present invention, preferably, the process parameters of the solution electrospinning machine include: the voltage of the nozzle is 8 to 25 kV, the voltage of the receiver is -1 kV to -10 kV; both nozzles are perpendicular to the receiver, the included angle between the two nozzles is 0 to 180°, the vertical distance between the two nozzles and the receiver is 10 to 500 mm, and the solution spraying speed of the two nozzles is 1.0 to 5.0 mL / h.

[0036] In this invention, the vertical distance between the nozzle and the receiver is an important parameter affecting the uniformity of nanofiber membrane formation and the fiber diameter. In order to obtain uniform fibers, the vertical distance between the nozzle and the receiver is preferably 10-200 mm.

[0037] According to the present invention, preferably, the orifice diameter of each of the two nozzles is independently 0.1-1.0 mm.

[0038] According to the present invention, preferably, the receiver is in the shape of a plane, a curved surface, an arc surface, or a circular roller.

[0039] According to the present invention, preferably, the receiver is in the shape of a circular roller, preferably, the roller diameter is 100-318mm, the roller length is 100-600mm, and the roller speed is 10-500m / min.

[0040] According to the present invention, preferably, it further includes a side-blowing device for blowing the surface of the receiver.

[0041] Preferably, the side-blowing air is at least one of nitrogen, air, and carbon dioxide.

[0042] More preferably, the velocity of the side-blowing air is 0.05-0.8 m / s, and the air temperature is 20-80℃.

[0043] The method for preparing composite aliphatic-aromatic copolyester-chitosan nanofiber membranes provided by this invention is universally applicable. Functional substances can be added to either the aliphatic-aromatic copolyester spinning solution or the chitosan spinning solution to form a doped spinning solution, and functional nanofiber membranes can be prepared by electrospinning. For example, adding substances such as carbon nanotubes, metal oxide nanoparticles, and graphene oxide to the spinning solution and electrospinning to prepare conductive nanofiber membranes can produce flexible pressure sensor devices with high resolution and sensitivity. Furthermore, by spraying antibacterial and antiviral substances into the spinning solution or onto the surface of the formed fibers, the resulting fiber material possesses antibacterial and antiviral functions.

[0044] A third aspect of the present invention provides the application of the aforementioned composite nanofiber membrane in the fields of filtration materials, flexible pressure sensor devices, antibacterial and antiviral materials, and mulch protection materials.

[0045] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0046] The drug information in this invention is as follows:

[0047] Chitosan was purchased from Zhejiang Jinke Pharmaceutical Co., Ltd.

[0048] PBAT was purchased from BASF.

[0049] Example 1

[0050] A 10% (w / w) PBST (molecular weight 120,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 2:8) and a 6% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 70%) were sprayed from a 0.2 mm orifice nozzle onto a cylindrical rotating roller receiver at feeding rates of 1.5 mL / h and 1.0 mL / h, respectively. The nozzle was supplied with a +18 kV positive voltage, and the receiver with a -1 kV negative voltage. The nozzle and the rotating roller were perpendicular. The nozzles are spaced 60mm and 40mm apart, with an included angle of 180° between them. The rotating roller rotates at 100m / min while being simultaneously purged with nitrogen side-blowing at 0.05m / s and 60°C. This process yields a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 30% chitosan fibers, has an average fiber diameter of 600nm, a membrane thickness of 120μm, a tensile stress of 300KPa, and an elongation at break of 50%. The membrane porosity is 60%. A high-efficiency, low-resistance filter material prepared from this nanofiber membrane exhibits a filtration efficiency of 99.1% for non-oily particulate matter.

[0051] Example 2

[0052] A 6% (w / w) PBST (molecular weight 200,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 2:8) and a 10% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 90%) were sprayed from a 0.1 mm orifice nozzle onto a cylindrical rotating roller receiver at feeding rates of 5 mL / h and 1.0 mL / h, respectively. A +20 kV positive voltage was applied to the nozzle, and a -1 kV negative voltage was applied to the receiver. The vertical distance between the nozzle and the rotating roller was... Two nozzles, each 200mm in diameter and 200mm in diameter, were used with an included angle of 180°. The rotating roller rotated at 100m / min and was simultaneously purged with nitrogen side-blowing at 0.05m / s and 60°C to obtain a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contained 25% chitosan fibers, had an average fiber diameter of 200nm, a membrane thickness of 200μm, a tensile stress of 500KPa, and an elongation at break of 100%. The membrane porosity was 20%. The high-efficiency, low-resistance filter material prepared from the nanofiber membrane achieved a filtration efficiency of 99.8% for non-oily particulate matter.

[0053] Example 3

[0054] A 30% (w / w) PBST (molecular weight 120,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 5:5) and a 10% (w / w) chitosan (molecular weight 400,000) acetic acid aqueous solution (acetic acid concentration 90%) were sprayed from a 1.0 mm orifice nozzle onto a cylindrical rotating roller receiver at feeding rates of 1.5 mL / h and 3.0 mL / h, respectively. The nozzle was supplied with a +25 kV positive voltage, and the receiver with a -5 kV negative voltage. The nozzle and the rotating roller were perpendicular. The nozzles are spaced 500 mm and 10 mm apart, with an included angle of 180° between them. The rotating roller rotates at 500 m / min while being simultaneously purged by a side-blowing airflow at 0.8 m / s and 80°C. This process yields a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 60% chitosan fibers, has an average fiber diameter of 800 nm, a membrane thickness of 300 μm, a tensile stress of 1000 kPa, and an elongation at break of 500%. The membrane porosity is 50%. The high-efficiency, low-resistance filter material prepared from this nanofiber membrane achieves a filtration efficiency of 99.2% for non-oily particulate matter.

[0055] Example 4

[0056] A 12% (w / w) PBST (molecular weight 180,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 4:6) and a 7% (w / w) chitosan (molecular weight 80,000) acetic acid aqueous solution (acetic acid concentration 90%) were sprayed from a 0.2 mm orifice nozzle onto a cylindrical rotating roller receiver at feeding rates of 1.5 mL / h and 1.0 mL / h, respectively. The nozzle was supplied with a +18 kV positive voltage, and the receiver with a -2 kV negative voltage. The nozzle and the rotating roller were perpendicular. The nozzles are spaced 300mm apart, with an included angle of 90° between them. The rotating roller rotates at 200m / min while being simultaneously purged with a side-blowing airflow of 0.6m / s and 60°C. This process yields a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 28% chitosan fibers, has an average fiber diameter of 300nm, a membrane thickness of 150μm, a tensile stress of 200KPa, and an elongation at break of 18%. The membrane porosity is 50%. The high-efficiency, low-resistance filter material prepared from this nanofiber membrane achieves a filtration efficiency of 99.9% for non-oily particulate matter.

[0057] Example 5

[0058] A 12% (w / w) PBST (molecular weight 180,000) hexafluoroisopropanol-dichloromethane solution (hexafluoroisopropanol to dichloromethane volume ratio 7:3) and a 7% (w / w) chitosan (molecular weight 80,000) acetic acid aqueous solution (acetic acid concentration 90%) were sprayed from a 0.2 mm orifice nozzle onto a cylindrical rotating roller receiver at feeding rates of 1.5 mL / h and 1.0 mL / h, respectively. The nozzle was supplied with a +20 kV positive voltage, and the receiver with a -10 kV negative voltage. The nozzle and the rotating roller... The vertical distances between the two nozzles are 300mm and 300mm, the included angle between the two nozzles is 180°, the rotation speed of the roller is 200m / min, and the roller is simultaneously subjected to side blowing air at 0.6m / s and 60°C to obtain a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 28% chitosan fibers, has an average fiber diameter of 300nm, a membrane thickness of 150μm, a tensile stress of 200KPa, and an elongation at break of 18%. The membrane porosity is 50%. The high-efficiency, low-resistance filter material prepared from this nanofiber membrane has a filtration efficiency of no less than 99.9% for non-oily particulate matter.

[0059] Example 6

[0060] A 12% (w / w) PBST (molecular weight 180,000) N,N-dimethylformamide-dichloromethane solution (N,N-dimethylformamide to dichloromethane volume ratio 5:5) and a 7% (w / w) chitosan (molecular weight 80,000) acetic acid aqueous solution (acetic acid concentration 90%) were sprayed from 0.2 mm orifice nozzles onto a cylindrical roller receiver at feeding rates of 1.5 mL / h and 1.0 mL / h, respectively. A +20 kV positive voltage was applied to the nozzle, and a -10 kV negative voltage was applied to the receiver. The vertical distances between the nozzles and the rotating roller are 300mm and 300mm respectively, with an included angle of 180° between the two nozzles. The rotating roller rotates at a speed of 200m / min, and simultaneously receives a side-blowing airflow of 0.6m / s and 60°C to purge the roller, resulting in a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 30% chitosan fibers, has an average fiber diameter of 400nm, a membrane thickness of 200μm, a tensile stress of 300KPa, and an elongation at break of 60%. The membrane porosity is 60%. The high-efficiency, low-resistance filter material prepared from this nanofiber membrane has a filtration efficiency of no less than 99.5% for non-oily particulate matter.

[0061] Example 7

[0062] A 12% (w / w) PBST (molecular weight 180,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 3:7) and a 7% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 90%) were prepared. 3% carbon nanotubes were added to the PBST solution. The solutions were sprayed from a 0.1 mm aperture nozzle onto a cylindrical roller receiver at feed rates of 1.5 mL / h and 1.0 mL / h, respectively. A +18 kV positive voltage was applied to the nozzle. A -2kV negative voltage was applied to the device, with the vertical distances between the nozzles and the rotating rollers being 100mm and 100mm respectively, an angle of 180° between the two nozzles, and a roller rotation speed of 100m / min. Simultaneously, the rollers were purged with a 0.6m / s, 60℃ airflow to the side, resulting in a PBST-chitosan composite nanofiber membrane. The chitosan fiber content was 30%, the average fiber diameter in the nanofiber membrane was 100nm, the membrane thickness was 100μm, the tensile stress was 300KPa, and the elongation at break was 30%. The membrane porosity was 80%. A flexible pressure sensor device prepared using this nanofiber membrane had a resolution of 0.5N and a sensitivity of 10kPa. -1 It has a compressive fatigue resistance of 20,000 cycles.

[0063] Example 8

[0064] A 12% (w / w) PBST (molecular weight 180,000) hexafluoroisopropanol-dichloromethane solution (hexafluoroisopropanol to dichloromethane volume ratio 7:3) and a 7% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 90%) were prepared. 3% carbon nanotubes were added to the PBST solution. The solutions were sprayed from a 0.4 mm orifice nozzle onto a cylindrical roller receiver at feed rates of 2.5 mL / h and 2.0 mL / h, respectively. A +18 kV positive voltage was applied to the nozzle, and a -2 kV negative voltage was applied to the receiver. The voltage was set at 150mm between the nozzle and the rotating roller, with a vertical distance of 150mm between the two nozzles and an angle of 180° between them. The rotating roller rotated at 100m / min and was simultaneously purged with a side-blowing airflow of 0.6m / s and 60°C to obtain a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contained 30% chitosan fibers, had an average fiber diameter of 800nm, a membrane thickness of 200μm, a tensile stress of 300KPa, and an elongation at break of 60%. The membrane porosity was 60%. A flexible pressure sensor device prepared using this nanofiber membrane had a resolution of 0.5N and a sensitivity of 10kPa. -1 It has a compressive fatigue resistance of 20,000 cycles.

[0065] Example 9

[0066] A 12% (w / w) PBST (molecular weight 180,000) N,N-dimethylformamide-dichloromethane solution (N,N-dimethylformamide to dichloromethane volume ratio 5:5), a 7% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 90%), and 3% carbon nanotubes were added to the PBST solution. The solutions were sprayed from a 0.1 mm aperture nozzle onto a cylindrical roller receiver at feed rates of 1.5 mL / h and 1.0 mL / h, respectively. A +18 kV positive voltage was applied to the nozzle, and the receiver was subjected to... A -2kV negative voltage was applied, with vertical distances between the nozzles and the rotating rollers of 150mm and 150mm respectively, an included angle of 180° between the two nozzles, and a rotating roller speed of 100m / min. Simultaneously, the rotating roller was subjected to a side-blowing airflow of 0.6m / s and 60℃ to obtain a PBST-chitosan composite nanofiber membrane. The PBST-chitosan composite nanofiber membrane contains 30% chitosan fibers, has an average fiber diameter of 100nm, a membrane thickness of 150μm, a tensile stress of 200KPa, and an elongation at break of 50%. The membrane porosity is 70%. A flexible pressure sensor device prepared using this nanofiber membrane has a resolution of 0.5N and a sensitivity of 10kPa. -1 It has a compressive fatigue resistance of 20,000 cycles.

[0067] Example 10

[0068] A 12% (w / w) PBST (molecular weight 180,000) N,N-dimethylformamide-dichloromethane solution (N,N-dimethylformamide to dichloromethane volume ratio 5:5) and a 7% (w / w) chitosan (molecular weight 40,000) acetic acid aqueous solution (acetic acid concentration 90%) were prepared. 2% silver nitrate was added to the chitosan solution. The solutions were sprayed from 0.1 mm aperture nozzles onto a cylindrical roller receiver at feed rates of 1.5 mL / h and 1.0 mL / h, respectively. A +18 kV positive voltage was applied to the nozzle, and a -18 kV positive voltage was applied to the receiver. A PBST-chitosan composite nanofiber membrane was obtained by applying a 2kV negative voltage, with the nozzles and rollers at vertical distances of 150mm and 150mm respectively, an included angle of 90°, and a roller speed of 100m / min. Simultaneously, the roller was purged with a 0.6m / s, 60℃ airflow. The membrane contained 30% chitosan fibers, with an average fiber diameter of 100nm, a membrane thickness of 150μm, a tensile stress of 200KPa, and an elongation at break of 50%. The membrane porosity was 70%. Antibacterial and antiviral materials prepared using this nanofiber membrane exhibited a 99% inhibition rate against Escherichia coli and Staphylococcus aureus.

[0069] Example 11

[0070] According to Example 1, the raw material was changed from PBST to PBAT (molecular weight 120,000), while other process conditions remained unchanged, to obtain a PBAT-chitosan composite nanofiber membrane. In this PBAT-chitosan composite nanofiber membrane, the chitosan fiber content was 30%, the average fiber diameter was 600 nm, the membrane thickness was 120 μm, the tensile stress was 300 kPa, and the elongation at break was 50%. The membrane porosity was 60%. A high-efficiency, low-resistance filter material was prepared from this nanofiber membrane, achieving a filtration efficiency of 99.1% for non-oily particulate matter.

[0071] Example 12

[0072] According to Example 9, the raw material was changed from PBST to PBAT (molecular weight 120,000), while other process conditions remained unchanged, to obtain a PBAT-chitosan composite nanofiber membrane. In this PBAT-chitosan composite nanofiber membrane, the chitosan fiber content was 30%, the average fiber diameter was 100 nm, the membrane thickness was 150 μm, the tensile stress was 200 kPa, and the elongation at break was 50%. The membrane porosity was 70%. A flexible pressure sensor device prepared using this nanofiber membrane had a resolution of 0.5 N and a sensitivity of 10 kPa. -1 It has a compressive fatigue resistance of 20,000 cycles.

[0073] Example 13

[0074] According to Example 10, the raw material was changed from PBST to PBAT (molecular weight 120,000), while other process conditions remained unchanged, to obtain a PBAT-chitosan composite nanofiber membrane. In this PBAT-chitosan composite nanofiber membrane, the chitosan fiber content was 30%, the average fiber diameter was 100 nm, the membrane thickness was 150 μm, the tensile stress was 200 kPa, and the elongation at break was 50%. The membrane porosity was 70%. The antibacterial and antiviral material prepared using this nanofiber membrane showed an inhibition rate of 99% against Escherichia coli and 99% against Staphylococcus aureus.

[0075] Example 14

[0076] The only difference between this embodiment and Example 1 is that the PBST mass concentration is 20 wt% and the chitosan mass concentration is 1 wt%, while other conditions remain unchanged. The resulting PBST-chitosan composite nanofiber membrane contains 0.5% chitosan fibers, has an average fiber diameter of 1000 nm, a membrane thickness of 200 μm, a tensile stress of 100 kPa, and an elongation at break of 15%. The membrane porosity is 70%, and the filter material prepared from this membrane exhibits a filtration efficiency of 70% for non-oily particulate matter.

[0077] Example 15

[0078] The only difference between this embodiment and Example 1 is that the nozzle is subjected to +30kV, the receiver has no voltage, and other conditions remain unchanged. The resulting PBST-chitosan composite nanofiber membrane contains 2% chitosan fibers, has an average fiber diameter of 1000nm, a nanofiber membrane thickness of 200μm, a tensile stress of 100KPa, and an elongation at break of 15%. The membrane porosity is 70%. A high-efficiency, low-resistance filter material prepared from this nanofiber membrane exhibits a filtration efficiency of 70% for non-oily particulate matter.

[0079] Comparative Example 1

[0080] A 10% (w / w) PBST (molecular weight 120,000) trifluoroacetic acid-dichloromethane solution (trifluoroacetic acid to dichloromethane volume ratio 2:8) was sprayed from a 0.2 mm orifice nozzle onto a cylindrical rotating roller receiver at a feed rate of 1.5 mL / h. The nozzle was supplied with a +18 kV positive voltage, and the receiver with a -1 kV negative voltage. The vertical distance between the nozzle and the roller was 60 mm, and the roller rotated at 100 m / min. Simultaneously, the roller was purged with nitrogen gas at 0.05 m / s and 60 °C. This yielded a PBST nanofiber membrane with an average fiber diameter of 600 nm, a membrane thickness of 150 μm, a tensile stress of 400 kPa, and an elongation at break of 120%. The membrane porosity was 50%. A high-efficiency, low-resistance filter material prepared from this nanofiber membrane achieved a filtration efficiency of 98.1% for non-oily particulate matter.

[0081] Comparative Example 2

[0082] The only difference between this comparative example and Example 1 is that the solvent for PBST is dichloromethane solution, which cannot be used for electrospinning.

[0083] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0084] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A composite nanofiber membrane, characterized by, The composite nanofiber membrane comprises aliphatic-aromatic copolyester fibers and chitosan fibers. The content of chitosan fibers in the composite nanofiber membrane is 10-60 wt%, preferably 25-50 wt%.

2. The composite nanofiber membrane of claim 1, wherein, The average diameter of fibers in the composite nanofiber membrane is ≤800 nm, preferably 50-500 nm.

3. The composite nanofiber membrane of claim 1, wherein, The composite nanofiber membrane further comprises functional nanoparticles; the functional nanoparticles are preferably at least one of carbon nanotubes, metal oxide nanoparticles and graphene oxide. The content of the functional nanoparticles is 1-6 wt% based on the total weight of the composite nanofiber membrane, preferably 3-6 wt%.

4. The composite nanofiber membrane of claim 1, wherein, The aliphatic-aromatic copolyester is polybutylene terephthalate-co-adipate and / or polybutylene terephthalate-co-succinate. The weight average molecular weight of the aliphatic-aromatic copolyester is ≥80000, preferably 120000-200000. The weight average molecular weight of the chitosan is 40000-400000, preferably 80000-300000.

5. The composite nanofiber membrane of claim 1, wherein, The porosity of the nanofiber membrane is 20-90%, the tensile stress of the nanofiber membrane is not less than 200 KPa, and the elongation at break is not less than 18%.

6. The method of producing a composite nanofiber membrane according to any one of claims 1 to 5, characterized by, The method comprises the following steps: (1) obtaining aliphatic-aromatic copolyester solution and chitosan solution respectively; (2) using a solution electrospinning machine to spray the aliphatic-aromatic copolyester solution and the chitosan solution from two nozzles onto the same receiver to obtain the composite nanofiber membrane.

7. The production method according to claim 6, wherein The solvent of the aliphatic-aromatic copolyester solution is dichloromethane or a mixed solvent containing dichloromethane, and the mass concentration of the aliphatic-aromatic copolyester is 3-15 wt%, preferably 5-12 wt%. Preferably, the solvent of the aliphatic-aromatic copolyester solution further contains at least one of trifluoroacetic acid, hexafluoroisopropanol and N,N-dimethylformamide. More preferably, the solvent of the aliphatic-aromatic copolyester solution is selected from at least one of a trifluoroacetic acid-dichloromethane system with a volume ratio of 1:9-5:5, a hexafluoroisopropanol-dichloromethane system with a volume ratio of 2:8-7:3 and an N,N-dimethylformamide-dichloromethane system with a volume ratio of 2:8-4:

6.

8. The production method according to claim 6, wherein The solvent of the chitosan solution is aqueous acetic acid, and the mass concentration of the chitosan is 3-15 wt%, preferably 5-10 wt%. Preferably, the solvent of the chitosan solution is aqueous acetic acid with an acetic acid mass concentration of 70-90 wt%.

9. The production method according to claim 6, wherein The process parameters of the solution electrospinning machine include: the voltage of the nozzles is 8-25 kV, and the voltage of the receiver is -1 kV to -10 kV; both nozzles are perpendicular to the receiver, the included angle between the two nozzles is 0-180°, and the vertical distance between each nozzle and the receiver is independently 10-500 mm, preferably 10-200 mm; the speed of the solution sprayed from the two nozzles is independently 1.0-5.0 mL / h.

10. The production method according to claim 6, wherein The pore diameter of each nozzle is independently 0.1-1.0 mm.

11. The production method according to claim 6, wherein The shape of the receiver is a plane, a curved surface, an arc surface or a round roller.

12. The production method according to claim 11, wherein The shape of the receiver is a round roller, preferably, the roller diameter is 100-318 mm, the roller length is 100-600 mm, and the roller rotation speed is 10-500 m / min.

13. The production method according to claim 6, wherein Further comprising setting a side blowing device to blow the surface of the receiver; Preferably, the side blowing is at least one of nitrogen, air and carbon dioxide; More preferably, the speed of the side blowing is 0.05-0.8 m / s, and the wind temperature is 20-80℃.

14. The method of making according to any one of claims 6-13, wherein, The preparation method further comprises adding functional nanoparticles into the aliphatic-aromatic copolyester solution and / or the chitosan solution; or spraying a functional nanoparticle solution on the surface of the composite nanofiber membrane.

15. Application of the composite nanofiber membrane according to any one of claims 1-5 in the fields of filtering materials, flexible pressure sensor devices, antibacterial and antiviral materials and mulching protective materials.