Composite fiber membrane and method for producing the same

Abstract

This application discloses a composite fiber membrane and its preparation method, relating to the field of composite material technology. The preparation method includes: in-situ modification of a composite fiber membrane precursor with stearic acid to obtain the composite fiber membrane; the composite fiber membrane precursor is a polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures. The composite fiber membrane proposed in this application, through in-situ modification of the polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures using stearic acid, imparts hydrophobic properties to the composite fiber membrane. This prevents the rapid erosion of the zinc oxide nanostructures by environmental water molecules in humid environments, avoiding the problem of explosive release and rapid depletion of zinc ions in a short time, ultimately leading to antibacterial failure.

Description

Technical Field

[0001] This application relates to the field of composite materials technology, and in particular to a composite fiber membrane and its preparation method. Background Technology

[0002] The main technical routes for preparing polypropylene carbonate / nano zinc oxide (PPC / ZnO) composite fiber membranes include physical blending, traditional electrospinning combined with hydrothermal methods, and conjugated electrospinning technology. The mainstream nanostructure preparation often employs electrospinning to first prepare zinc-containing PPC fibers, followed by hydrothermal growth of ZnO in a high-temperature, high-pressure reactor. Traditional hydrothermal methods, carried out in a closed reactor, lack precise control over liquid flow rate and temperature, easily leading to inconsistent growth kinetics and uneven size distribution of ZnO nanorods, making it difficult to meet the requirements of industrial-grade precision manufacturing. Furthermore, existing electrospun composite fiber membranes lack effective surface hydrophobic protection structures. In actual humid environments, environmental water molecules easily erode the exposed ZnO surface, triggering a burst release of zinc ions, causing the material to lose its antibacterial ability in a short time, failing to meet the long-lasting antibacterial requirements of medical excipients or packaging. Summary of the Invention

[0003] The main objective of this application is to propose a composite fiber membrane and its preparation method, aiming to solve the problem of insufficient antibacterial time of existing composite fiber membranes.

[0004] To achieve the above objectives, the method for preparing the composite fiber membrane proposed in this application includes: The composite fiber membrane was prepared by in-situ modification of the composite fiber membrane precursor with stearic acid. The composite fiber membrane precursor is a polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures.

[0005] Preferably, the step of in-situ modification of the composite fiber membrane precursor with stearic acid includes: immersing the composite fiber membrane precursor in a stearic acid ethanol solution.

[0006] Preferably, the concentration of stearic acid in the stearic acid ethanol solution is 5-10 mmol / L; The immersion temperature is 25~30℃ and the immersion time is 20~40 min.

[0007] Preferably, the method for preparing the composite fiber membrane precursor includes: A solvent was prepared by mixing acetone and dimethylformamide; a growth solution was prepared by mixing zinc nitrate, hexamethylenetetramine, and ammonia. Add 8-20 wt% polypropylene carbonate to the solvent, then add zinc acetate dihydrate to the solvent, and mix to obtain a composite fiber membrane precursor solution. The composite fiber membrane precursor was prepared by electrospinning the composite fiber membrane precursor solution. The composite fiber membrane precursor was heat-treated and then mixed with the growth solution for a hydrothermal reaction to obtain the composite fiber membrane precursor.

[0008] Preferably, the volume ratio of acetone to dimethylformamide in the solvent is 1:1 to 1:3; In the growth solution, the molar ratio of zinc nitrate to hexamethylenetetramine is 1:0.8 to 1:1.2, and the concentration of ammonia is 0.3 to 0.8 mol / L. The mass ratio of polypropylene carbonate to zinc acetate dihydrate is 1:0.1 to 1:0.7.

[0009] Preferably, the electrospinning voltage is 15~20 kV, the receiving distance is 15~20 cm, and the propulsion flow rate is 0.5~1 mL / h; The hydrothermal reaction is carried out at a temperature of 80~98℃ for a time of 1.5~2.5 h.

[0010] Preferably, the composite fiber membrane is prepared using a multi-channel high-throughput automated liquid phase reaction platform, which is equipped with a microfluidic pump system, a multi-channel independent temperature control module, and an automatic liquid addition robotic arm; the flow rate control accuracy of the microfluidic pump system is ±0.2% rd.

[0011] This application also proposes a composite fiber membrane prepared by the preparation method proposed in this application, wherein the water contact angle of the surface of the composite fiber membrane is ≥150°.

[0012] Preferably, the composite fiber membrane maintains an inhibition rate of over 90% against Escherichia coli after being soaked in PBS buffer for 7 days.

[0013] Preferably, the composite fiber membrane exhibits a mass loss rate of more than 90% within 6 months under soil burial conditions.

[0014] The composite fiber membrane proposed in this application is made hydrophobic by in-situ modification of a polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures using stearic acid. This prevents the problem of rapid erosion of the zinc oxide nanostructures by environmental water molecules in humid environments, which would lead to an explosive release and rapid depletion of zinc ions in a short period of time, ultimately resulting in antibacterial failure. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 A schematic flowchart illustrating the preparation method of the composite fiber membrane provided in this application; Figure 2 A schematic flowchart illustrating the preparation method of the composite fiber membrane precursor provided in this application; Figure 3 A schematic diagram of the structure of the multi-channel high-throughput automated liquid phase reaction platform provided in this application; Figure 4 Scanning electron microscope image of the composite fiber membrane prepared in Example 1 provided for this application; Figure 5 Antibacterial test diagram of the composite fiber membrane prepared in Example 1 of this application; Figure 6 Scanning electron microscope image of the composite fiber membrane prepared in Example 2 provided in this application; Figure 7 Antibacterial test diagram of the composite fiber membrane prepared in Example 2 provided in this application; Figure 8 Scanning electron microscope image of the composite fiber membrane prepared in Comparative Example 1 provided for this application; Figure 9 Antibacterial test diagram of the composite fiber membrane prepared in Comparative Example 1 provided for this application.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0021] With the increasing severity of antibiotic resistance, the development of non-antibiotic physical antibacterial materials has become a research hotspot in the biomedical and packaging fields. In recent years, metal / metal oxide nanostructures have attracted attention due to their antibacterial properties. However, the toxicity of certain metals poses a threat to human health and the environment, limiting their application in the biomedical field. In contrast, nano-zinc oxide (ZnO), due to its low toxicity, controllable morphology, and unique physicochemical properties, is becoming an alternative to traditional antibiotic materials. When reduced to the nanoscale, zinc oxide exhibits enhanced antibacterial effects, disrupting bacterial integrity through interaction with bacterial membranes or penetration of bacterial cells. Polypropylene carbonate (PPC), a biodegradable plastic copolymerized from carbon dioxide and propylene oxide, is often chosen as a matrix material due to its excellent biocompatibility and environmental value, and is often combined with zinc oxide nanostructures possessing physical bactericidal mechanisms to enhance functionality.

[0022] Currently, the main technical routes for preparing PPC / ZnO composite fiber membranes include physical blending, traditional electrospinning combined with hydrothermal methods, and conjugate electrospinning. The mainstream nanostructure preparation often employs electrospinning to first prepare zinc-containing PPC fibers, followed by hydrothermal growth of ZnO in a high-temperature, high-pressure reactor. However, existing technologies still have shortcomings in terms of R&D efficiency, manufacturing precision, and long-term application. First, for multi-component blending processes, due to the complex proportions of multiple components, existing technologies lack efficient screening methods, relying mainly on manual trial and error. This results in extremely long and inefficient cycles for screening over a hundred sets of process parameters, making it difficult to accurately determine the optimal performance formulation. Second, traditional hydrothermal methods are carried out in closed reactors, lacking precise control over liquid flow rate and temperature, which easily leads to inconsistent growth kinetics and uneven size distribution of ZnO nanorods, making it difficult to meet the requirements of industrial-grade precision manufacturing. Finally, existing electrospun composite fiber membranes lack an effective surface hydrophobic protective structure. When used in actual humid environments, environmental water molecules can easily corrode the exposed ZnO surface, causing an explosive release of zinc ions. This results in the material losing its antibacterial ability in a short period of time, failing to meet the long-lasting antibacterial requirements of medical excipients or packaging.

[0023] Based on this, this application proposes a method for preparing a composite fiber membrane, such as... Figure 1 As shown, it includes: S101. The composite fiber membrane precursor is modified in situ with stearic acid to obtain the composite fiber membrane.

[0024] The composite fiber membrane precursor is a polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures.

[0025] By using stearic acid to in-situ modify polypropylene carbonate fiber membranes loaded with zinc oxide nanostructures, the composite fiber membrane is made hydrophobic, thus preventing the problem of rapid erosion of zinc oxide nanostructures by environmental water molecules in humid environments, which would lead to the explosive release and rapid depletion of zinc ions in a short period of time, ultimately resulting in antibacterial failure.

[0026] In some embodiments, the step of in-situ modification of the composite fiber membrane precursor with stearic acid includes immersing the composite fiber membrane precursor in a stearic acid ethanol solution.

[0027] In some embodiments, the concentration of stearic acid in the stearic acid-ethanol solution is 5–10 mmol / L. For example, the concentration of stearic acid in the stearic acid-ethanol solution is 5 mmol / L, 6 mmol / L, 7 mmol / L, 8 mmol / L, 9 mmol / L, or 10 mmol / L, etc. The immersion temperature is 25–30°C. For example, the immersion temperature can be 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C, etc. The immersion time is 20–40 min. For example, the immersion time is 20 min, 25 min, 30 min, 35 min, or 40 min, etc.

[0028] By forming a stearic acid layer on the surface of the composite fiber membrane precursor through in-situ modification, the prepared composite fiber membrane has a hydrophobic protective effect in the early stage, thus maintaining a relatively stable structure in the early stage of degradation. Subsequently, under the action of soil microorganisms, the stearic acid layer is preferentially decomposed, inducing the exposure of PPC matrix and ZnO and accelerating hydrolysis. The mass loss rate within 6 months is greater than 90%, and the final degradation products are carbon dioxide, water and trace zinc ions, with no persistent organic pollutant residues.

[0029] In some embodiments, the preparation method of the composite fiber membrane precursor, such as Figure 2 As shown, it includes: S201. A acetone (AC) and dimethylformamide (DMF) are mixed to prepare a solvent; zinc nitrate (ZNH), hexamethylenetetramine (HMTA) and ammonia (NH3˙H2O) are mixed to prepare a growth solution.

[0030] In some embodiments, the volume ratio of acetone to dimethylformamide in the solvent is 1:1 to 1:3. For example, the volume ratio of acetone to dimethylformamide in the solvent can be 1:1, 1:2, or 1:3, etc. The molar ratio of zinc nitrate to hexamethylenetetramine in the growth solution is 1:0.8 to 1:1.2. For example, the molar ratio of zinc nitrate to hexamethylenetetramine in the growth solution can be 1:0.8, 1:0.9, 1:1, 1:1.1, or 1:1.2, etc. The concentration of ammonia water is 0.3 to 0.8 mol / L. For example, the concentration of ammonia water can be 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, or 0.8 mol / L, etc.

[0031] S202. Add 8-20 wt% polypropylene carbonate (PPC) to the solvent, then add zinc acetate dihydrate (ZAD), and mix to obtain a composite fiber membrane precursor solution.

[0032] For example, the amount of polypropylene carbonate added is 8 wt%, 10 wt%, 15 wt%, or 20 wt%.

[0033] In some embodiments, the mass ratio of polypropylene carbonate to zinc acetate dihydrate is 1:0.1 to 1:0.7. For example, the mass ratio of polypropylene carbonate to zinc acetate dihydrate can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, etc.

[0034] S203. The composite fiber membrane precursor is prepared by electrospinning the composite fiber membrane precursor solution.

[0035] In some embodiments, the electrospinning voltage is 15-20 kV. For example, the electrospinning voltage can be 15 kV, 16 kV, 17 kV, 18 kV, 19 kV, or 20 kV, etc. The receiving distance is 15-20 cm. For example, the receiving distance can be 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, or 20 cm, etc. The propulsion flow rate is 0.5-1 mL / h. For example, the propulsion flow rate can be 0.5 mL / h, 0.6 mL / h, 0.7 mL / h, 0.8 mL / h, 0.9 mL / h, or 1 mL / h, etc.

[0036] S204. The composite fiber membrane precursor is heat-treated, then mixed with the growth solution and subjected to a hydrothermal reaction to obtain the composite fiber membrane precursor.

[0037] In some embodiments, the hydrothermal reaction temperature is 80–98°C. For example, the hydrothermal reaction temperature can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, or 98°C, etc. The hydrothermal reaction time is 1.5–2.5 h. For example, the hydrothermal reaction time can be 1.5 h, 2 h, or 2.5 h, etc.

[0038] In some embodiments, the composite fiber membrane is prepared using a multi-channel, high-throughput, automated liquid-phase reaction platform; please refer to [link to relevant documentation]. Figure 3 The multi-channel high-throughput automated liquid phase reaction platform includes a microfluidic pump system, a multi-channel independent temperature control module, and an automatic liquid addition robotic arm. The flow rate control accuracy of the microfluidic pump system is ±0.2% rd.

[0039] Furthermore, the preparation method of the composite fiber membrane includes: S301: Electrospinning preparation of ZAD-PPC nanofiber membranes PPC / ZAD solution was prepared according to the specified ratio, and the solvent was a mixture of acetone (AC) and dimethylformamide (DMF). ZAD-PPC nanofiber membrane was prepared by electrospinning. The applied voltage during electrospinning was 15-20 kV, the receiving distance was 15-20 cm, the feed rate was 0.5-1 mL / h, the ambient temperature was 25℃, and the relative humidity was 40-50%. A PPC-ZAD composite nanofiber membrane with uniform thickness was obtained by collecting it on an aluminum foil receiving plate.

[0040] S302: ZnO nanostructures with consistent orientation are grown on the fiber surface.

[0041] Electrospun nanofiber membranes were cut into 5 cm × 5 cm samples and heat-treated at 55–120 °C for 20–24 h to decompose ZnO onto PPC fibers, forming a zinc oxide seed layer. The PPC nanofiber membranes containing ZnO seeds were placed in a platform reactor array. The platform control system activated a microfluidic pump to extract zinc nitrate solution, hexamethylenetetramine solution, and ammonia water from the raw material storage tank according to a preset molar ratio. After online premixing in the fluid pipeline, these solutions were simultaneously injected into multiple parallel reactors with a flow rate accuracy of ±0.2% rd. A hydrothermal reaction was carried out at 80–98 °C for 1.5–2.5 h, resulting in the growth of uniformly oriented ZnO nanorod structures on the fiber surface.

[0042] S303: In-situ hydrophobic modification After the hydrothermal reaction is completed, the platform automatically executes the liquid replacement procedure: First, the growth waste liquid in the reactor is sucked out and emptied through the negative pressure system, and deionized water is automatically injected for cleaning; then, the microfluidic pump accurately draws 5~10 mmol / L stearic acid ethanol solution and quantitatively injects it into the reactor until the fiber membrane is completely submerged. It is then immersed at 25~30℃ for 20~40 min, followed by cleaning with ethanol and hot air drying.

[0043] The aforementioned high-throughput liquid-phase reaction platform can process more than five liquids per batch. The flow rate control accuracy of the microfluidic pump is ±0.2%rd. Each run can prepare 10 reactors simultaneously. By accelerating the material screening process and minimizing human error and environmental impact, the efficiency of material synthesis is significantly improved.

[0044] By precisely controlling the flow rate of each solution, the ratio of ZAD / HMTA / ammonia and the amount of stearic acid ethanol solution injected into the micro-reaction system are ensured, thereby guaranteeing a high degree of consistency in the growth of nanostructures.

[0045] This application also proposes a composite fiber membrane prepared using the aforementioned preparation method. This composite fiber membrane adopts all the technical solutions of all the above embodiments, and therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here. The water contact angle of the composite fiber membrane surface is ≥150°.

[0046] In some implementations, the composite fiber membrane maintained an inhibition rate of over 90% against Escherichia coli after being soaked in PBS buffer for 7 days.

[0047] In some implementations, the composite fiber membrane exhibits a mass loss rate of more than 90% within 6 months under soil burial conditions.

[0048] The following specific examples provide further details.

[0049] The tests used in the examples were performed according to the following standards: (1) Microscopic morphology and size test index: GB / T 16594-2008 "General Rules for Measurement Methods of Micrometer-scale Length by Scanning Electron Microscopy"; (2) Surface wettability (contact angle) test index: GB / T 14216-2008 "Determination of wetting tension of plastic films and sheets"; (3) Antibacterial performance test indicators: GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Vibration method" and GB / T 31402-2015 "Test method for antibacterial properties of plastic surfaces"; (4) Biodegradability test index: GB / T 19277.1-2011 "Determination of final aerobic biodegradation capacity of materials under controlled composting conditions by reaction analysis method for measuring carbon dioxide released - Part 1: General method".

[0050] Example 1 (1) Acetone (AC) and N,N-dimethylformamide (DMF) were mixed at a volume ratio of 1:1 to obtain a solvent. 10 wt% polypropylene carbonate (PPC) was weighed and dissolved in the solvent, and zinc acetate dihydrate (ZAD) was added. The mass ratio of ZAD to PPC was controlled to be 1:0.5 to obtain a mixed solution. The precursor fiber membrane was prepared by electrospinning using the mixed solution. The electrospinning parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and flow rate 0.8 mL / h. The precursor fiber membrane was cut and placed in an oven at 105℃ for 24 h for heating treatment. ZnO seed crystals were generated in situ on the precursor fiber membrane to obtain the pre-formed membrane.

[0051] (2) The pre-formed membrane was placed in a high-throughput reaction unit. The high-throughput reaction unit automatically aspirated zinc nitrate hexahydrate (ZNH) solution and hexamethylenetetramine (HMTA) solution with a molar ratio of 1:1 using a microfluidic pump, and added an ammonia solution with a concentration of 0.5 mol / L. The precision temperature control was turned on, and the hydrothermal temperature was set to 95℃. The reaction was carried out for 2 h.

[0052] (3) After the reaction is completed, the high-throughput reaction unit is automatically drained and cleaned, and 5 mmol / L stearic acid ethanol solution is injected. The mixture is then immersed at 30°C for 30 min to obtain the PPC / ZnO composite fiber membrane.

[0053] The nanorods of the prepared PPC / ZnO composite fiber membrane (e.g.) Figure 4 The aspect ratio (RSD) of the sample (as shown) was 4.2%, and the surface water contact angle was 152°. Antimicrobial properties were tested using plate counts (e.g., ...). Figure 5 As shown in the figure, the prepared PPC / ZNnO composite fiber membrane exhibits excellent antibacterial properties. Further antibacterial testing using the inhibition zone method revealed an inhibition zone diameter of 17.88 mm for Escherichia coli. After 7 days of PBS immersion, the antibacterial rate remained above 92%, and after 180 days of soil burial, the mass loss was >94%.

[0054] Example 2 (1) Acetone (AC) and N,N-dimethylformamide (DMF) were mixed at a volume ratio of 1:1 to obtain a solvent. 10 wt% polypropylene carbonate (PPC) was weighed and dissolved in the solvent, and zinc acetate dihydrate (ZAD) was added. The mass ratio of ZAD to PPC was controlled to be 1:0.7 to obtain a mixed solution. The precursor fiber membrane was prepared by electrospinning using the mixed solution. The electrospinning parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and flow rate 0.5 mL / h. The precursor fiber membrane was cut and placed in an oven at 110℃ for 24 h for heating treatment. ZnO seed crystals were generated in situ on the precursor fiber membrane to obtain the pre-formed membrane.

[0055] (2) The pre-formed membrane was placed in a high-throughput reaction unit. The high-throughput reaction unit automatically aspirated zinc nitrate hexahydrate (ZNH) solution and hexamethylenetetramine (HMTA) solution with a molar ratio of 1:1 using a microfluidic pump, and added an ammonia solution with a concentration of 0.5 mol / L. The precision temperature control was turned on, and the hydrothermal temperature was set to 98℃. The reaction was carried out for 2 h.

[0056] (3) After the reaction is completed, the high-throughput reaction unit is automatically drained and cleaned, and 10 mmol / L stearic acid ethanol solution is injected. The mixture is then immersed at 30°C for 20 min to obtain the PPC / ZnO composite fiber membrane.

[0057] In the prepared PPC / ZnO composite fiber membrane, the ZnO nanostructures tend to be more clustered (e.g., Figure 6 As shown), the surface water contact angle is 154°. Antimicrobial activity was tested using a plate count test (e.g., ...). Figure 7 As shown in the figure, the prepared PPC / ZNnO composite fiber membrane exhibits excellent antibacterial properties. Further antibacterial testing using the inhibition zone method revealed an inhibition zone diameter of 16.20 mm for E. coli. After 7 days of PBS immersion, the antibacterial rate remained above 90%, and after 180 days of soil burial, the mass loss was >90%.

[0058] Comparative Example 1 (1) Acetone (AC) and N,N-dimethylformamide (DMF) were mixed at a volume ratio of 1:1 to obtain a solvent. 10 wt% polypropylene carbonate (PPC) was weighed and dissolved in the solvent, and zinc acetate dihydrate (ZAD) was added. The mass ratio of ZAD to PPC was controlled to be 1:0.3 to obtain a mixed solution. The precursor fiber membrane was prepared by electrospinning using the mixed solution. The electrospinning parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and flow rate 0.5 mL / h. The precursor fiber membrane was cut and placed in an 80℃ oven for 24 h for heating treatment to generate ZnO seeds in situ on the precursor fiber membrane, thus obtaining the pre-formed membrane.

[0059] (2) The pre-formed membrane was placed in a high-throughput reaction unit. The high-throughput reaction unit automatically aspirated zinc nitrate hexahydrate (ZNH) solution and hexamethylenetetramine (HMTA) solution with a molar ratio of 1:1 using a microfluidic pump, and added an ammonia solution with a concentration of 0.5 mol / L. The precision temperature control was turned on, and the hydrothermal temperature was set to 85℃. The reaction was carried out for 2.5 h.

[0060] (3) After the reaction is completed, the high-throughput reaction unit is automatically drained and cleaned, and 5 mmol / L stearic acid ethanol solution is injected. The mixture is then immersed at 30°C for 40 min to obtain the PPC / ZnO composite fiber membrane.

[0061] The prepared PPC / ZnO composite fiber membrane tends to have a more granular structure (e.g. Figure 8 As shown), the surface water contact angle is 148°. Antimicrobial activity was tested using a plate count test (e.g., ...). Figure 9 As shown in the figure, using a lower hydrothermal temperature (85℃) and a lower precursor ratio (1:0.3), the morphology of ZnO crystals formed is mainly "granular". The physical puncture ability of this structure is weaker than that of "nanorobars", so its antibacterial performance will naturally decrease, and there will be more colonies in the plate. Further antibacterial tests were conducted using the inhibition zone method, and the diameter of the inhibition zone for E. coli was measured to be 13.36 mm. After soaking in PBS for 7 days, the inhibition rate remained above 85%, and the mass loss was >90% after burying in soil for 180 days.

[0062] Comparative Example 2 (1) Acetone (AC) and N,N-dimethylformamide (DMF) were mixed at a volume ratio of 1:1 to obtain a solvent. 10 wt% polypropylene carbonate (PPC) was weighed and dissolved in the solvent, and zinc acetate dihydrate (ZAD) was added. The mass ratio of ZAD to PPC was controlled to be 1:0.5 to obtain a mixed solution. The precursor fiber membrane was prepared by electrospinning using the mixed solution. The electrospinning parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and flow rate 0.8 mL / h. The precursor fiber membrane was cut and placed in an oven at 105℃ for 24 h for heating treatment. ZnO seed crystals were generated in situ on the precursor fiber membrane to obtain the pre-formed membrane.

[0063] (2) The pre-formed membrane was placed in a high-throughput reaction unit. The high-throughput reaction unit automatically aspirated zinc nitrate hexahydrate (ZNH) solution and hexamethylenetetramine (HMTA) solution with a molar ratio of 1:1 using a microfluidic pump, and added an ammonia solution with a concentration of 0.5 mol / L. The precision temperature control was turned on, and the hydrothermal temperature was set to 95℃. The reaction was carried out for 2.5 h to complete the preparation.

[0064] Comparative Example 3 (1) Acetone (AC) and N,N-dimethylformamide (DMF) were mixed at a volume ratio of 1:1 to obtain a solvent. 10 wt% polypropylene carbonate (PPC) was weighed and dissolved in the solvent, and zinc acetate dihydrate (ZAD) was added. The mass ratio of ZAD to PPC was controlled to be 1:0.5 to obtain a mixed solution. The precursor fiber membrane was prepared by electrospinning using the mixed solution. The electrospinning parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and flow rate 0.8 mL / h. The precursor fiber membrane was cut and placed in an oven at 105℃ for 24 h for heating treatment. ZnO seed crystals were generated in situ on the precursor fiber membrane to obtain the pre-formed membrane.

[0065] (2) Mix zinc nitrate hexahydrate (ZNH) solution and hexamethylenetetramine (HMTA) solution at a molar ratio of 1:1, and add ammonia solution with a concentration of 0.5 mol / L to prepare growth solution. Place the pre-made film in the growth solution and heat it to 95°C in a constant temperature oil bath using a magnetic stirrer for 2 h.

[0066] (3) After the reaction is complete, remove the membrane and soak it in a petri dish containing 5 mmol / L stearic acid solution for 30 min to complete the preparation.

[0067] The performance test results of the composite fiber membranes prepared in Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1.

[0068] Table 1 Performance Test of PPC / ZnO Composite Fiber Membrane

[0069] As shown in Table 1, Comparative Example 2, which did not undergo in-situ modification with stearic acid in the prepared composite fiber membrane precursor, exhibited a significantly weakened antibacterial effect. Comparative Example 3 employed a traditional manual preparation method. During this process, stirring created complex turbulence, resulting in inconsistent zinc ion concentrations on the fiber surfaces at different locations. Furthermore, the large beaker heated in a bath often exhibited a significant temperature difference between the edge and the center. This uneven growth environment led to some ZnO growing faster than others, resulting in inconsistent final sizes.

[0070] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing a composite fiber membrane, characterized in that, include: The composite fiber membrane was prepared by in-situ modification of the composite fiber membrane precursor with stearic acid. The composite fiber membrane precursor is a polypropylene carbonate fiber membrane loaded with zinc oxide nanostructures.

2. The method for preparing the composite fiber membrane as described in claim 1, characterized in that, The step of in-situ modification of the composite fiber membrane precursor with stearic acid includes: immersing the composite fiber membrane precursor in a stearic acid ethanol solution.

3. The method for preparing the composite fiber membrane as described in claim 2, characterized in that, The concentration of stearic acid in the stearic acid ethanol solution is 5~10 mmol / L; The immersion temperature is 25~30℃ and the immersion time is 20~40 min.

4. The method for preparing the composite fiber membrane as described in claim 1, characterized in that, The method for preparing the composite fiber membrane precursor includes: A solvent was prepared by mixing acetone and dimethylformamide; a growth solution was prepared by mixing zinc nitrate, hexamethylenetetramine, and ammonia. Add 8-20 wt% polypropylene carbonate to the solvent, then add zinc acetate dihydrate to the solvent, and mix to obtain a composite fiber membrane precursor solution. The composite fiber membrane precursor was prepared by electrospinning the composite fiber membrane precursor solution. The composite fiber membrane precursor was heat-treated and then mixed with the growth solution for a hydrothermal reaction to obtain the composite fiber membrane precursor.

5. The method for preparing the composite fiber membrane as described in claim 4, characterized in that, The volume ratio of acetone to dimethylformamide in the solvent is 1:1 to 1:3; The molar ratio of zinc nitrate to hexamethylenetetramine in the growth solution is 1:0.8 to 1:1.2, and the concentration of ammonia is 0.3 to 0.8 mol / L. The mass ratio of polypropylene carbonate to zinc acetate dihydrate is 1:0.1 to 1:0.

7.

6. The method for preparing the composite fiber membrane as described in claim 4, characterized in that, The electrospinning voltage is 15~20 kV, the receiving distance is 15~20 cm, and the propulsion flow rate is 0.5~1 mL / h; The hydrothermal reaction is carried out at a temperature of 80~98℃ for a time of 1.5~2.5 h.

7. The method for preparing the composite fiber membrane according to any one of claims 1 to 6, characterized in that, The composite fiber membrane is prepared using a multi-channel high-throughput automated liquid phase reaction platform, which is equipped with a microfluidic pump system, a multi-channel independent temperature control module, and an automatic liquid addition robotic arm; the flow rate control accuracy of the microfluidic pump system is ±0.2% rd.

8. A composite fiber membrane prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The water contact angle of the composite fiber membrane surface is ≥150°.

9. The composite fiber membrane as described in claim 8, characterized in that, The composite fiber membrane maintained an inhibition rate of over 90% against Escherichia coli after being soaked in PBS buffer for 7 days.

10. The composite fiber membrane as described in claim 8, characterized in that, The composite fiber membrane experienced a mass loss rate of over 90% within 6 months under soil burial conditions.

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