A quaternary ammonium salt chitosan antibacterial composite nanofiber membrane and its preparation method

Abstract

The present invention relates to a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane and a preparation method thereof, comprising the following steps: S1, preparing a spinning solution: mixing and stirring a quaternary ammonium salt chitosan solution and a polyvinyl alcohol solution, and standing to prepare a spinning solution A; mixing and stirring a polyacrylic acid solution and a polyvinyl alcohol solution, and standing to prepare a spinning solution B; S2, electrospinning: injecting the spinning solution A and the spinning solution B into a main injection pump and an auxiliary injection pump respectively, and simultaneously electrospinning in a high-voltage electrostatic field to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane; S3, thermal crosslinking treatment: placing the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven for thermal crosslinking to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane. The present invention combines electrospinning and thermal crosslinking technologies, which not only retains the antibacterial groups in the quaternary ammonium salt chitosan, but also improves the water resistance and stability of the prepared fiber membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial materials, and particularly relates to a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane and a preparation method thereof. Background Art

[0002] Electrospinning is a method for preparing nanofibers using a high-voltage electrostatic process. Due to its advantages such as high controllability of fiber size, high porosity, large specific surface area, and a wide variety of spinnable substances, it has become a hot topic for preparing nanofiber materials in recent years.

[0003] The application of electrospinning in natural polymer materials has always been restricted by the polyelectrolyte effect of polymers. Among them, polysaccharide polymer materials represented by chitosan have always been the focus of research. Quaternary ammonium salt chitosan is a water-soluble derivative of chitosan after quaternary ammonium salt modification. It has the biological and chemical properties of chitosan and good antibacterial properties. Therefore, it shows broad application prospects in the fields of biomedicine, water treatment, etc. However, due to the introduction of extremely hydrophilic quaternary ammonium groups during the quaternization process, it swells severely in aqueous solution, resulting in a certain degree of decline in the mechanical properties, water resistance, etc. of the fabricated membrane products. Using a crosslinking agent to modify it is an effective method to improve its physical and chemical properties. Among them, glutaraldehyde has become one of the most widely used chitosan crosslinking agents due to its large crosslinking degree and high stability after crosslinking. However, due to the relatively high toxicity of glutaraldehyde and the problem of yellowing of the fiber membrane during the crosslinking process, its application is restricted to a certain extent. Polyvinyl alcohol is a water-soluble polymer with good spinnability and high mechanical properties, so it is also widely used in the above fields, but it also has the problem of easy hydrolysis.

[0004] Therefore, providing an environmentally friendly, safe and excellent physical and chemical property antibacterial fiber membrane production process has become an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: The present invention provides a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane and a preparation method thereof. Its process control is simple, the spinnability of the spinning solution is good, and the spun quaternary ammonium salt chitosan antibacterial composite nanofiber membrane has high antibacterial property, excellent water resistance and environmental protection, and broad application prospects.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] In the first aspect, the present invention provides a preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane, comprising the following steps:

[0008] S1. Prepare the spinning solution: Mix and stir the quaternary ammonium salt chitosan solution and the polyvinyl alcohol solution, and let it stand to prepare spinning solution A; mix and stir the polyacrylic acid solution and the polyvinyl alcohol solution, and let it stand to prepare spinning solution B.

[0009] S2. Electrospinning: Inject spinning solution A and spinning solution B into the main and auxiliary injection pumps respectively, and perform electrospinning simultaneously in a high-voltage electrostatic field to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane.

[0010] S3. Thermal cross-linking treatment: Place the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven for thermal cross-linking to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane.

[0011] A preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane proposed by the present invention first combines quaternary ammonium salt chitosan and polyacrylic acid with polyvinyl alcohol respectively to prepare a two-component electrospinning solution for electrospinning, which effectively avoids the polyester reaction between polyacrylic acid and quaternary ammonium salt chitosan and improves the stability of the spinning solution; then uses the carboxyl groups in polyacrylic acid to perform dehydration condensation with the hydroxyl groups in polyvinyl alcohol and quaternary ammonium salt chitosan under the action of heat to form ester bonds for connection, thereby obtaining a water-insoluble quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane, which not only retains the effective antibacterial groups in quaternary ammonium salt chitosan, but also improves the water resistance and stability of the prepared antibacterial composite nanofiber membrane, and abandons the use of glutaraldehyde, which is more environmentally friendly and safe.

[0012] Optionally, in step S1, the mass concentration of the quaternary ammonium salt chitosan solution is 7-8%, the mass concentration of the polyvinyl alcohol solution is 8-10%, and the mass concentration of the polyacrylic acid solution is 8-10%.

[0013] According to the above description, the purpose of the mass concentration selected for the above raw materials is to control the viscosity of the spinning solution and improve the spinnability of the spinning solution.

[0014] Optionally, in step S1, the mixing mass ratio of the quaternary ammonium salt chitosan solution to the polyvinyl alcohol solution is 0.5-1:6-9; the mixing mass ratio of the polyacrylic acid solution to the polyvinyl alcohol solution is 0.5-1:6-9.

[0015] According to the above description, the quaternary ammonium salt chitosan in this mass ratio endows the fiber membrane with good antibacterial effects, the purpose of polyacrylic acid is to make the fiber membrane have better structural stability and water resistance, and polyvinyl alcohol mainly plays the role of improving the spinnability of the spinning solution.

[0016] Optionally, in step S1, the stirring time is 1-2 h, and the stirring temperature is 20-30 °C.

[0017] According to the above description, the process of mixing and stirring strengthens the uniformity of the spinning solution, which is beneficial to smooth spinning.

[0018] Optionally, in step S1, the viscosities of spinning solution A and spinning solution B are 300 - 550 mPa·S.

[0019] According to the above description, within this viscosity range, the spun fibers have a finer diameter, while enhancing the continuity of spinning and avoiding clogging of the spinning needle holes.

[0020] Optionally, in step S2, the electrospinning conditions are as follows: the spinning voltage is 22 - 24 KV, the advancing speed is 0.36 - 0.45 mL / h, the distance between two needles is 0.5 - 1 cm, the outer diameter of the needle is 0.7 mm, the distance from the needle to the receiving plate is 10 - 15 cm, the surface of the roller receiver uses smooth non - woven fabric for receiving, and the receiving area is 0.075 m 2 , and the electrospinning time is 7 - 14 h.

[0021] According to the above description, under the control of the above process parameters, it is beneficial to the stable progress of continuous production, and a fiber membrane with a large specific surface area can be obtained to improve the antibacterial property of the fiber membrane. At the same time, using smooth non - woven fabric is beneficial to the smooth peeling of the electrospun fiber membrane without damaging the fiber membrane itself.

[0022] Optionally, in step S3, the thermal cross - linking temperature is 130 - 150 °C, and the thermal cross - linking time is 15 - 30 min.

[0023] According to the above description, adopting the method of thermal cross - linking can make the electrospun fiber membrane form a breathable electrospun fiber membrane with good tensile strength and hydrolysis resistance.

[0024] In the second aspect, the present invention also provides a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane, which is prepared by the above - mentioned preparation method.

[0025] Among them, the technical effects corresponding to the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane provided in the second aspect refer to the relevant descriptions of the preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane provided in the first aspect. Description of the Drawings

[0026] Figure 1 It is the SEM diagram of Example 3 of the present invention. Among them, Figure (a) is the front - view SEM diagram of Example 3, Figure (b) is the cross - section SEM diagram of Example 3, and Figure (c) is the fiber diameter distribution diagram of Example 3;

[0027] Figure 2This is a comparison chart of the antibacterial effects of Example 3 of the present invention and the blank sample. Among them, Figure (a) is the colony distribution chart of Escherichia coli in the blank sample, Figure (b) is the antibacterial effect chart of Escherichia coli after adding Example 3, Figure (c) is the colony distribution chart of Staphylococcus aureus in the blank sample, and Figure (d) is the antibacterial effect chart of Staphylococcus aureus after adding Example 3;

[0028] Figure 3 This is the thermogravimetric curve of Example 2 and Example 3 of the present invention;

[0029] Figure 4 This is the hydrolysis resistance test chart of Example 1 and Comparative Examples 1-2 of the present invention. Among them, Figure (a) is Comparative Example 1, Figure (b) is Example 1, and Figure (c) is Comparative Example 2. Detailed implementation mode

[0030] To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to be able to convey the scope of the present invention completely to those skilled in the art.

[0031] Example 1

[0032] A preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane includes the following steps:

[0033] S1. Prepare the spinning solution: Use deionized water to prepare a 8% quaternary ammonium salt chitosan solution, an 8% polyvinyl alcohol solution, and an 8% polyacrylic acid solution. Mix the 8% quaternary ammonium salt chitosan solution and the 8% polyvinyl alcohol solution at a mass ratio of 1:9 and stir at room temperature of 25°C for 2 h, then let it stand for 1 h to prepare spinning solution A; Mix the 8% polyacrylic acid solution and the 8% polyvinyl alcohol solution at a mass ratio of 1:9 and stir at room temperature of 25°C for 2 h, then let it stand for 1 h to prepare spinning solution B; The viscosities of spinning solution A and spinning solution B are 300-550 mPa·S.

[0034] S2. Electrospinning: Inject spinning solution A and spinning solution B into the main and auxiliary injection pumps respectively, and perform electrospinning simultaneously in a high-voltage electrostatic field. Set the electrospinning conditions as follows: the electrospinning voltage is 22 KV, the feeding speed is 0.4 mL / h, the distance between the two needles is 1 cm, the outer diameter of the needle is 0.7 mm, the distance from the needle to the receiving plate is 14 cm, the surface of the drum receiver is received by smooth non-woven fabric, and the receiving area is 0.075 m 2 , and the electrospinning time is 7 h to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane.

[0035] S3. Thermal crosslinking treatment: Place the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven at 130 °C for thermal crosslinking for 30 min to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane.

[0036] The quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane prepared by the method of thermal crosslinking through the cross-contact points of fiber filaments based on the electrospinning technology in the embodiments of the present invention avoids the problem that the air permeability and antibacterial effect are greatly reduced due to the filling of polyester between fiber filaments compared with the fiber membrane obtained by the impregnation filling thermal crosslinking method of directly mixing an aqueous solution of quaternary ammonium salt chitosan, polyacrylic acid and polyvinyl alcohol.

[0037] Example 2

[0038] A preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane includes the following steps:

[0039] S1. Prepare the spinning solution: Prepare a quaternary ammonium salt chitosan solution with a mass concentration of 8% and polyvinyl alcohol solutions of 8% and 9% and a polyacrylic acid solution with 9% using deionized water. Mix the 8% quaternary ammonium salt chitosan solution and the 8% polyvinyl alcohol solution at a mass ratio of 1:9 and stir at room temperature of 25 °C for 2 h, then let it stand for 1 h to prepare spinning solution A; Mix the 9% polyacrylic acid solution and the 9% polyvinyl alcohol solution at a mass ratio of 1:9 and stir at room temperature of 25 °C for 2 h, then let it stand for 1 h to prepare spinning solution B; The viscosities of spinning solution A and spinning solution B are 300 - 550 mPa·S.

[0040] S2. Electrospinning: Inject spinning solution A and spinning solution B into the main and auxiliary injection pumps respectively, and perform electrospinning simultaneously in a high-voltage electrostatic field. Set the electrospinning conditions as follows: The spinning voltage is 23 KV, the feeding speed is 0.36 mL / h, the distance between the two needles is 0.8 cm, the outer diameter of the needle is 0.7 mm, the distance from the needle to the receiving plate is 12 cm, the surface of the roller receiver is received with a smooth non-woven fabric, and the receiving area is 0.075 m 2 , and the electrospinning time is 7 h to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane.

[0041] S3. Thermal crosslinking treatment: Place the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven at 140 °C for thermal crosslinking for 20 min to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane.

[0042] Example 3

[0043] A preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane includes the following steps:

[0044] S1. Preparation of spinning solution: Use deionized water to prepare a quaternary ammonium salt chitosan solution with a mass concentration of 8%, polyvinyl alcohol solutions of 8% and 10%, and a polyacrylic acid solution of 10%. Mix and stir the 8% quaternary ammonium salt chitosan solution and the 8% polyvinyl alcohol solution at a mass ratio of 1:9 at room temperature of 25°C for 2 h, and let it stand for 1 h to prepare spinning solution A; Mix and stir the 10% polyacrylic acid solution and the 10% polyvinyl alcohol solution at a mass ratio of 1:9 at room temperature of 25°C for 2 h, and let it stand for 1 h to prepare spinning solution B; The viscosities of spinning solution A and spinning solution B are 300 - 550 mPa·S.

[0045] S2. Electrospinning: Inject spinning solution A and spinning solution B into the main and auxiliary injection pumps respectively, and perform electrospinning simultaneously in a high-voltage electrostatic field. Set the electrospinning conditions as follows: The spinning voltage is 24 KV, the feeding speed is 0.38 mL / h, the distance between the two needles is 0.8 cm, the outer diameter of the needle is 0.7 mm, the distance from the needle to the receiving plate is 10 cm, the surface of the drum receiver is received with smooth non-woven fabric, and the receiving area is 0.075 m 2 , and the electrospinning time is 14 h to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane.

[0046] S3. Thermal cross-linking treatment: Place the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven at 150°C for thermal cross-linking for 15 min to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane, and its fiber morphology is as shown in Figure 1 (a) and (b) in, and the fiber diameter distribution is as shown in Figure 1 (c) in.

[0047] As can be seen from Figure 1 , a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane with uniform diameter was successfully prepared by the method of electrospinning.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that the preparation process does not contain polyacrylic acid solution (i.e., only spinning solution A).

[0050] Comparative Example 2

[0051] The difference between this comparative example and Comparative Example 1 is that the preparation process further includes the step of placing the quaternary ammonium salt chitosan / polyvinyl alcohol antibacterial composite nanofiber membrane obtained in Comparative Example 1 in glutaraldehyde vapor for cross-linking.

[0052] Performance testing

[0053] Perform physical and chemical property tests on the antibacterial composite nanofiber membranes prepared in Examples 1 - 3 and Comparative Example 1, and the results are recorded in Table 1 and Figure 2 .

[0054] Table 1 Test Results of Physicochemical Properties

[0055] Sample Tensile strength Tensile fracture stress Antibacterial rate against Escherichia coli Antibacterial rate against Staphylococcus aureus Example 1 4.92 MPa 2.64 MPa 86.2％ 78.9％ Example 2 5.25 MPa 2.65 MPa 85.4％ 80.1％ Example 3 6.4 MPa 5.07 MPa 99.7％ 85.9％ Comparative example 1 1.85 MPa 1.13 MPa Hydrolysis cannot be tested Hydrolysis cannot be tested

[0056] From Figure 2 It can be seen that after culturing the blank sample, a large number of Escherichia coli colonies (a) and Staphylococcus aureus colonies (c) appeared on the surface of the culture dish. After adding the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane prepared in Example 3, a small number of Escherichia coli colonies (b) and Staphylococcus aureus colonies (d) were observed in the culture dish. This indicates that the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane prepared in this example has good antibacterial effects on both Escherichia coli and Staphylococcus aureus. Further, through the relevant data in Table 1, it can be known that the antibacterial rates of the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membranes prepared in Examples 1-3 of the present invention against Escherichia coli and Staphylococcus aureus both meet the textile antibacterial standard (≥70%), and compared with Comparative Example 1 lacking polyacrylic acid crosslinking, its anti-hydrolysis ability and mechanical properties have been greatly improved.

[0057] The thermal stability tests were carried out on the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membranes with different thicknesses prepared in Examples 2 and 3, and the results are as Figure 3 shown.

[0058] From Figure 3 it can be seen that the trends of the thermogravimetric curves of the 0.05 mm thick quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane prepared in Example 2 and the 0.1 mm thick one prepared in Example 3 are roughly the same. The weight loss starts at about 200 °C, reaches the maximum weight loss rate at 340 °C, and terminates the thermal decomposition at about 500 °C, indicating good thermal stability.

[0059] The hydrolysis resistance tests were carried out on the antibacterial composite nanofiber membranes prepared in Example 1 and Comparative Examples 1-2, and the results are as Figure 4 shown.

[0060] From Figure 4 it can be known that the uncrosslinked Comparative Example 1 showed a phenomenon of rapid dissolution in water, while there was no obvious change in Example 1 crosslinked by polyacrylic acid heat and Comparative Example 2 crosslinked by glutaraldehyde vapor. This shows that crosslinking improves the water resistance of the fiber membrane.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a quaternary ammonium salt chitosan antibacterial composite nanofiber membrane, comprising the following steps: S1. Prepare the spinning solution: Mix and stir the quaternary ammonium salt chitosan solution and the polyvinyl alcohol solution, and let it stand to prepare spinning solution A; Mix and stir the polyacrylic acid solution and the polyvinyl alcohol solution, and let it stand to prepare spinning solution B. S2. Electrospinning: Inject spinning solution A and spinning solution B into the main and auxiliary injection pumps respectively, and carry out electrospinning simultaneously in a high-voltage electrostatic field to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane. S3. Thermal crosslinking treatment: Place the quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylic acid antibacterial composite nanofiber membrane in an oven for thermal crosslinking to obtain a quaternary ammonium salt chitosan / polyvinyl alcohol / polyacrylate antibacterial composite nanofiber membrane. In step S3, the thermal crosslinking temperature is 130 - 150 °C, and the thermal crosslinking time is 15 - 30 min.

2. The preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane according to claim 1, characterized in that, In step S1, the mass concentration of the quaternary ammonium salt chitosan solution is 7 - 8%, the mass concentration of the polyvinyl alcohol solution is 8 - 10%, and the mass concentration of the polyacrylic acid solution is 8 - 10%.

3. The preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane according to claim 1, characterized in that, In step S1, the mixing mass ratio of the quaternary ammonium salt chitosan solution to the polyvinyl alcohol solution is 0.5 - 1:6 - 9; the mixing mass ratio of the polyacrylic acid solution to the polyvinyl alcohol solution is 0.5 - 1:6 - 9.

4. The preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane according to claim 1, characterized in that, In step S1, the stirring time is 1 - 2 h, and the stirring temperature is 20 - 30 °C.

5. The preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane according to claim 1, characterized in that, In step S1, the viscosities of spinning solution A and spinning solution B are 300 - 550 mPa·S.

6. The preparation method of the quaternary ammonium salt chitosan antibacterial composite nanofiber membrane according to claim 1, characterized in that, In step S2, the electrospinning conditions are as follows: the spinning voltage is 22 - 24 KV, the feeding speed is 0.36 - 0.45 mL / h, the distance between two needles is 0.5 - 1 cm, the outer diameter of the needle is 0.7 mm, the distance from the needle to the receiving plate is 10 - 15 cm, the surface of the roller receiver is received by smooth non-woven fabric, and the receiving area is 0.075 m 2 , and the electrospinning time is 7 - 14 h.

7. A quaternary ammonium salt chitosan antibacterial composite nanofiber membrane prepared by the preparation method according to any one of claims 1 - 6.

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