A graphene-reinforced polyamide antibacterial composite fiber and a preparation method and application thereof

Abstract

The present application relates to the technical field of modified polyamide, and particularly relates to a graphene-reinforced polyamide antibacterial composite fiber and a preparation method and application thereof.The present application comprises the following steps: S1, preparing edge carboxylated graphene; S2, preparing PEG grafted graphene; S3, preparing a gallic acid-dopamine amide compound; S4, preparing a GA-PEG-dopamine-G composite material; S5, preparing a master batch by mixing the GA-PEG-dopamine-G composite material with polyamide 6 granules; and performing melt spinning on the master batch to obtain the graphene-reinforced polyamide antibacterial composite fiber.The composite fiber has excellent mechanical properties, particularly elongation at break and tensile strength, and also has excellent antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of modified polyamide technology, and in particular to a graphene-reinforced polyamide antibacterial composite fiber, its preparation method, and its application. Background Technology

[0002] PA6 (polyamide 6) is a condensation polymer with wide applications in fibers and engineering materials. PA6 is highly hygroscopic, readily absorbing moisture from the environment, which leads to decreased dimensional stability, affecting its mechanical properties and dimensional accuracy in humid environments. Its rigidity and strength also decrease. Furthermore, its mechanical properties are unsuitable for certain applications requiring high strength and high modulus, such as aerospace, automotive, and certain special types of engineering plastics. Current technologies generally improve the mechanical properties and water resistance of PA6 by introducing nanofillers.

[0003] With the improvement of living standards and the increase in leisure time, people have placed higher demands on the quality of clothing fabrics. Fashionable, healthy, comfortable, and casual clothing is becoming increasingly popular. PA6 (polyamide 6), as one of the four major synthetic fibers, still has room for improvement in its mechanical and antibacterial properties. Its application is limited in some fields with high fiber performance requirements, such as high-end textiles and medical and hygiene products. Current technologies generally involve adding graphene to PA6 to prepare composite fibers with high tensile strength and good antibacterial effects.

[0004] Graphene is a two-dimensional carbon nanomaterial with a hexagonal honeycomb lattice structure composed of carbon atoms with sp2 hybrid orbitals. It is considered the basic structural unit of some carbon allotropes of different dimensions, including zero-dimensional fullerenes, one-dimensional carbon nanotubes (CNTs), and three-dimensional graphite. Due to its excellent mechanical properties, excellent thermal conductivity, specific surface area, and excellent electronic transport properties, graphene has attracted great interest in its application in polymer / graphene nanocomposites.

[0005] Although graphene-modified polyamide 6 composites exhibit many excellent properties, such as improved mechanical properties and improved thermal stability, there are also some challenges and defects in practical applications and research. These mainly include: (1) Uniform dispersion of graphene in the polymer matrix is ​​a major challenge. Uneven dispersion can lead to inconsistencies in the properties of composites, and even agglomeration in local areas, which may weaken the overall performance of the material. (2) If the interfacial bonding force between graphene and PA6 is not strong, it will affect the effective transfer of load and reduce the mechanical properties of the composite. Optimizing interfacial interactions, such as by chemically modifying graphene or using coupling agents, is the key to improving the performance of composites. (3) In actual production, if the amount, type, or dispersion method of graphene is inappropriate, it may unexpectedly reduce some properties of the original PA6, such as toughness or processability.

[0006] Therefore, how to solve the various defects of graphene in polyamide 6 and enable the synergistic effect of the two is one of the technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a graphene-reinforced polyamide antibacterial composite fiber, its preparation method and application. The resulting composite fiber has excellent elongation at break and tensile strength, and also has antibacterial properties.

[0008] This invention provides a method for preparing graphene-reinforced polyamide antibacterial composite fibers, comprising the following steps:

[0009] S1. Preparation of edge-carboxylated graphene;

[0010] S2. Disperse edge-carboxylated graphene in buffer solution, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and terminal amino polyethylene glycol, and react; after the reaction is complete, dialyze and freeze-dry to obtain PEG-grafted graphene.

[0011] S3. Gallic acid was dissolved in anhydrous ethanol, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dopamine hydrochloride were added and reacted. After the reaction was completed, the mixture was rotary evaporated, deionized water was added, the pH was adjusted to 3-4, a precipitate was formed, the precipitate was collected by centrifugation, washed with water, and dried under vacuum to obtain the gallic acid-dopamine amide complex.

[0012] S4. Disperse PEG-grafted graphene in buffer solution, add gallic acid-dopamine amide complex, add dopamine hydrochloride, stir evenly, react, after the reaction is complete, centrifuge, collect the precipitate, wash, dry, and obtain GA-PEG-dopamine-G composite material.

[0013] S5.GA-PEG-dopamine-G composite material and polyamide 6 granules were used to make a masterbatch; the masterbatch was melt-spun to obtain graphene-reinforced polyamide antibacterial composite fiber.

[0014] This invention utilizes ball milling in the presence of dry ice to mechanically break the C-C bonds at the edges of graphene, generating active carbon sites. These sites react with CO2 released from the dry ice to form carboxyl groups, resulting in edge-selectively carboxylated graphene, providing active sites for subsequent reactions. Then, using an EDC / NHS activation system, the carboxyl groups on the edge-carboxylated graphene are activated to generate a stable NHS ester intermediate. Upon addition of terminal amino-terminated polyethylene glycol, the amino groups undergo an amidation reaction with the NHS ester, forming covalently linked PEG-grafted graphene. The introduction of the flexible PEG chain improves the dispersibility of graphene in PA6 and forms a flexible buffer layer at the interface. In anhydrous ethanol, EDC / NHS activates the carboxyl groups of gallic acid, which then undergoes an amidation reaction with the amino groups of dopamine hydrochloride, forming a gallic acid-dopamine amide complex. This complex covalently connects the antibacterial functional units of gallic acid with the anchoring units of dopamine, providing a structural basis for subsequent embedding into a polydopamine layer while ensuring the secure fixation of the antibacterial components. Free dopamine self-polymerizes to form a polydopamine layer, which coats the surface of PEG-grafted graphene. Simultaneously, dopamine units in the gallic acid-dopamine amide complex covalently cross-link with the polydopamine layer, becoming in-situ embedded within the polydopamine network. This provides abundant active groups, enhancing interfacial bonding with PA6. During melt blending with PA6, the amino and phenolic hydroxyl groups on the polydopamine layer surface react with the terminal carboxyl / amino groups of PA6 to form covalent bonds. PEG segments then physically entangle with PA6, achieving multiple interfacial bonding and improving mechanical properties. Gallic acid, covalently anchored in the fiber, exerts a long-lasting antibacterial effect.

[0015] Preferably, graphene is ball-milled in a container containing dry ice, then soaked in hydrochloric acid, filtered, washed, and the solid components are freeze-dried to obtain edge-carboxylated graphene.

[0016] Preferably, the thickness of the graphene sheets is 0.5-5 nm.

[0017] Preferably, the mass ratio of graphene to dry ice is 1:(10-30).

[0018] Preferably, the mass concentration of the hydrochloric acid is 0.5-2 mol / L.

[0019] Preferably, the mass ratio of edge-carboxylated graphene to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and terminal amino polyethylene glycol is 1:(0.4-0.5):(0.25-0.35):(0.4-0.6).

[0020] Preferably, the mass ratio of gallic acid to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dopamine hydrochloride is 1:(0.4-0.5):(0.25-0.35):(0.15-0.25).

[0021] Preferably, the mass ratio of PEG-grafted graphene to gallic acid-dopamine amide complex and dopamine hydrochloride is 1:(0.4-0.6):(0.05-0.15).

[0022] This invention employs a three-step modification process—PEG flexible grafting, gallic acid-dopamine covalent composite, and polydopamine coating—to construct a multi-level interfacial structure on the graphene surface, comprising a flexible intermediate layer, a functional anchoring layer, and an active outer shell. The PEG grafting layer improves graphene dispersion and buffers stress, the GA-DA covalent composite firmly anchors the antibacterial units, and the polydopamine coating provides abundant interfacial reaction sites. The synergistic effect of the three layers enables the composite fiber to maintain excellent antibacterial properties while significantly improving its elongation at break and tensile strength, achieving a balance between mechanical properties and functionality.

[0023] The polyamide antibacterial composite fiber prepared by the method described above is a polyamide antibacterial composite fiber based on graphene reinforcement.

[0024] The application of the polyamide antibacterial composite fiber prepared by the aforementioned method in fiber preparation.

[0025] This invention achieves controllable interface structure by limiting the amount of key raw materials used in the three-step modification process. The mass ratio of edge-carboxylated graphene to PEG ensures a moderate PEG grafting density; too low a density results in insufficient improvement in dispersibility, while too high a density hinders subsequent functional layer coating. The mass ratio of gallic acid to dopamine ensures that the GA-DA composite provides sufficient antibacterial units while effectively embedding them into the PDA layer. The mass ratio of PEG-grafted graphene to free dopamine guarantees an appropriate PDA layer thickness; too thin a layer results in weak GA-DA anchoring, while too thick a layer affects the direct interfacial bonding between graphene and PA6. Through synergistic optimization of the dosage range of each component, the overall performance of the composite material is optimized.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The polyamide 6 reinforced composite material prepared by this invention has high strength, excellent antibacterial properties and antioxidant capacity, good mechanical properties and strong water resistance.

[0028] 2. By introducing gallic acid and other raw materials, this invention solves the problems of uneven dispersion of graphene in polyamide 6 and weak interfacial bonding between graphene and PA6. The modified polyamide 6 material prepared has good stability and excellent mechanical properties, especially elongation at break and tensile strength.

[0029] 3. This invention achieves a balance between mechanical properties and functionality by using a three-step modification process involving PEG flexible grafting, gallic acid-dopamine covalent compounding, and polydopamine coating. The three-layer structure works synergistically to maintain excellent antibacterial properties while significantly improving the elongation at break and tensile strength of the composite fiber.

[0030] 4. By limiting the amount of key raw materials used in the three-step modification process, this invention achieves controllable interface structure and optimizes the comprehensive performance of the composite material through synergistic optimization of the dosage range of each component. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Amino-terminated polyethylene glycol, NH2-PEG-NH2, molecular weight 1000.

[0033] Example 1

[0034] This embodiment provides a graphene-reinforced polyamide antibacterial composite fiber, the preparation method of which includes the following steps:

[0035] S1. Preparation of edge-carboxylated graphene

[0036] 10g of graphene with a sheet thickness of 2nm was placed in a sealed container containing 200g of dry ice at a ball-to-material ratio of 1:20 and ball-milled at 500rpm for 36h. After ball milling, the graphene was soaked in 0.6L of 1mol / L hydrochloric acid solution for 12h to remove metallic impurities. The solution was then filtered, washed, and the solid components were freeze-dried for 48h to obtain edge-carboxylated graphene.

[0037] S2. Preparation of PEG-grafted graphene

[0038] 1.15 g of edge-carboxylated graphene was dispersed in 100 mL of 0.1 mol / L / pH 5.5 2-morpholine ethanesulfonic acid buffer and sonicated at 40 kHz for 1 h. 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added, and the mixture was stirred at 25 °C and 250 rpm for 30 min. 0.5 g of terminal amino polyethylene glycol was then added, and the mixture was stirred at 25 °C and 250 rpm for another 6 h. After the reaction was completed, the mixture was dialyzed with deionized water for 24 h, and the molecular weight cutoff was 12000. Then, it was freeze-dried for 48 h to obtain PEG-grafted graphene.

[0039] S3. Preparation of gallic acid-dopamine covalent complex

[0040] 1.15 g of gallic acid was dissolved in 50 mL of anhydrous ethanol, and 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added. The mixture was stirred at 25 °C and 250 rpm for 30 min to obtain an activated solution. 0.2 g of dopamine hydrochloride was dissolved in 10 mL of anhydrous ethanol and added dropwise to the above activated solution. The addition was carried out for 20 min, and the mixture was stirred at 25 °C and 250 rpm for 6 h. After the reaction was completed, the ethanol was removed by rotary evaporation, and 25 mL of deionized water was added to dissolve the precipitate. The pH was adjusted to 3 with 0.1 mol / L hydrochloric acid, and the precipitate was collected by centrifugation, washed with water, and dried under vacuum for 24 h to obtain the gallic acid-dopamine amide complex.

[0041] S4. Preparation of GA-PEG-dopamine-G composite material

[0042] 1.0 g of PEG-grafted graphene prepared by S2 was dispersed in 100 mL of 10 mmol / L, pH 8.5 Tris-HCl buffer and ultrasonically dispersed for 1 h to obtain a mixture. 0.5 g of gallic acid-dopamine amide complex prepared by S3 was dissolved in 5 mL of ethanol and added to the above mixture. At the same time, 0.1 g of dopamine hydrochloride was added, and the mixture was stirred evenly. The mixture was stirred at 25 °C and 250 rpm for 24 h. After the reaction was completed, the precipitate was collected by centrifugation, washed three times alternately with deionized water and ethanol, and dried under vacuum at 60 °C for 24 h to obtain the GA-PEG-dopamine-G composite material.

[0043] S5. Melt spinning to prepare composite fibers

[0044] 2g of GA-PEG-dopamine-G composite material and 48g of polyamide 6 (PA6) granules were melt-blended in an internal mixer at 180rpm and 240℃ for 30min to prepare a masterbatch. The masterbatch was then added to a plunger-type spinning machine and melt-spun through a 0.4mm orifice at 260℃ to obtain graphene-reinforced polyamide antibacterial composite fiber.

[0045] Example 2

[0046] This embodiment provides a graphene-reinforced polyamide antibacterial composite fiber, the preparation method of which includes the following steps:

[0047] S1. Preparation of edge-carboxylated graphene

[0048] 10 g of graphene with a sheet thickness of 2 nm was placed in a sealed container containing 200 g of dry ice at a ball-to-material ratio of 1:20 and ball-milled at 500 rpm for 2.5 h. After ball milling, the graphene was soaked in 0.6 L of 1 mol / L hydrochloric acid solution for 12 h to remove metallic impurities. The graphene was then filtered, washed, and freeze-dried for 48 h to obtain edge-carboxylated graphene.

[0049] S2. Preparation of PEG-grafted graphene

[0050] 1.15 g of edge-carboxylated graphene was dispersed in 100 mL of 0.1 mol / L, pH 5.5 2-morpholine ethanesulfonic acid buffer and sonicated at 40 kHz for 1 h. 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added, and the mixture was stirred at 25°C and 250 rpm for 30 min. Then, 0.6 g of terminal amino-terminated polyethylene glycol (molecular weight 1000) was added, and the mixture was stirred at 25°C and 250 rpm for 6 h. After the reaction was complete, the mixture was dialyzed against deionized water for 24 h (molecular weight cutoff 12000) and freeze-dried for 48 h to obtain PEG-grafted graphene.

[0051] S3. Preparation of gallic acid-dopamine covalent complex

[0052] 1.15 g of gallic acid was dissolved in 50 mL of anhydrous ethanol, and 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added. The mixture was stirred at 25°C and 250 rpm for 30 min to obtain an activated solution. 0.25 g of dopamine hydrochloride was dissolved in 10 mL of anhydrous ethanol and added dropwise to the above activated solution over 20 min. The mixture was stirred at 25°C and 250 rpm for 6 h. After the reaction was complete, the ethanol was removed by rotary evaporation, and the solution was dissolved in 25 mL of deionized water. The pH was adjusted to 3 with 0.1 mol / L hydrochloric acid, and a precipitate was formed. The precipitate was collected by centrifugation, washed with water, and dried under vacuum for 24 h to obtain the gallic acid-dopamine amide complex.

[0053] S4. Preparation of GA-PEG-dopamine-G composite material

[0054] 1.0 g of PEG-grafted graphene prepared by S2 was dispersed in 100 mL of 10 mmol / L Tris-HCl buffer (pH 8.5) and ultrasonically dispersed for 1 h. 0.5 g of gallic acid-dopamine amide complex prepared by S3 was dissolved in 5 mL of ethanol and added to the dispersion. Simultaneously, 0.15 g of dopamine hydrochloride was added, and the mixture was stirred thoroughly at 25°C and 250 rpm for 24 h. After the reaction was complete, the precipitate was collected by centrifugation, washed three times alternately with deionized water and ethanol, and dried under vacuum at 60°C for 24 h to obtain the GA-PEG-dopamine-G composite material.

[0055] S5. Melt spinning for preparing composite fibers

[0056] Two g of the GA-PEG-dopamine-G composite material prepared by S4 and 47 g of polyamide 6 (PA6) granules were melt-blended in an internal mixer at 180 rpm and 240°C for 30 min to prepare a masterbatch. The masterbatch was added to a plunger spinning machine and melt-spun through a spinneret with a diameter of 0.4 mm at 260°C to obtain graphene-reinforced polyamide antibacterial composite fiber.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 1 is that edge-carboxylated graphene was directly added to polyamide 6.

[0059] A graphene-modified polyamide 6 is prepared by the following steps:

[0060] S1. 10g of graphene (sheet thickness of 2nm) was ball-milled at 500rpm for 36h in a container containing 200g of dry ice. The ball-to-material ratio was 1:20. The graphene was soaked in 1mol / L hydrochloric acid for 12h, filtered, washed, and the solid components were freeze-dried for 48h to obtain edge carboxylated graphene.

[0061] S2. Mix 5g of edge-carboxylated graphene with 45g of polyamide 6 and then directly melt-blend in an internal mixer at 180rpm and 240℃ for 30min to prepare a masterbatch. The masterbatch is then melt-spun in a plunger-type spinning machine with a jet orifice diameter of 0.4mm at 260℃ to obtain graphene-modified polyamide 6.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that only gallic acid modification was used.

[0064] A graphene-reinforced polyamide antibacterial composite fiber, the preparation method of which includes the following steps:

[0065] S1. 10g of graphene (sheet thickness of 2nm) was ball-milled at 500rpm for 36h in a container containing 200g of dry ice. The ball-to-material ratio was 1:20. The graphene was soaked in 0.6L hydrochloric acid with 1mol / L for 12h, filtered, washed, and the solid components were freeze-dried for 48h to obtain edge carboxylated graphene.

[0066] S2. Add 1 mol / L sodium bicarbonate solution to 100 mL of gallic acid aqueous solution (containing 1.15 g of gallic acid) to adjust the pH to 6. Add 1.15 g of edge carboxyl graphene and mix ultrasonically at 40 kHz for 1.5 h. Add 0.34 g of copper oxide to the mixed solution and transfer it to a hydrothermal reactor for reaction. React at 90 °C for 12 h. After the reaction is completed, cool and centrifuge at 2000 rpm for 15 min. Wash and dry the precipitate to obtain gallic acid / edge carboxyl graphene composite material.

[0067] S3. After mixing 2g of gallic acid / edge carboxyl graphene composite material with 48g of polyamide 6, the mixture was directly melt-blended at 180rpm and 240℃ in an internal mixer for 30min to prepare a masterbatch. The masterbatch was then melt-spun at 260℃ using a plunger-type spinning machine with a jet orifice diameter of 0.4mm to obtain graphene-reinforced polyamide antibacterial composite fiber.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that only gallic acid and PEG modification were used.

[0070] A graphene-reinforced polyamide antibacterial composite fiber, the preparation method of which includes the following steps:

[0071] S1. Preparation of edge-carboxylated graphene

[0072] 10 g of graphene with a sheet thickness of 2 nm was placed in a sealed container containing 200 g of dry ice and ball-milled at 500 rpm for 2.5 h. After ball milling, it was soaked in 0.6 L of 1 mol / L hydrochloric acid solution for 12 h to remove metallic impurities. The solution was then filtered, washed, and freeze-dried for 48 h to obtain edge-carboxylated graphene.

[0073] S2. Preparation of PEG-grafted graphene

[0074] 1.15 g of edge-carboxylated graphene was dispersed in 100 mL of 0.1 mol / L, pH 5.5 2-morpholine ethanesulfonic acid buffer and sonicated at 40 kHz for 1 h. Then, 0.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3 g of N-hydroxysuccinimide were added, and the mixture was stirred at 25°C and 250 rpm for 30 min. Next, 0.5 g of amino-terminated polyethylene glycol (molecular weight 1000) was added, and the mixture was stirred at 25°C and 250 rpm for 6 h. After the reaction was complete, the mixture was dialyzed against deionized water for 24 h, the molecular weight cutoff was 12000, and the mixture was freeze-dried for 48 h to obtain PEG-grafted graphene.

[0075] S3. Gallic acid and PEG-grafted graphene composite

[0076] 1.0 g of PEG-grafted graphene prepared by S2 was dispersed in 100 mL of deionized water and ultrasonically dispersed at 40 kHz for 1 h to obtain a uniform dispersion. 0.5 g of gallic acid was dissolved in 10 mL of anhydrous ethanol and slowly added dropwise to the above dispersion. The mixture was stirred at 25 °C and 250 rpm for 24 h. After the reaction was complete, the precipitate was collected by centrifugation, washed three times alternately with deionized water and anhydrous ethanol, and dried under vacuum at 60 °C for 24 h to obtain the gallic acid / PEG-grafted graphene composite material.

[0077] S4. Melt spinning to prepare composite fibers

[0078] Two g of gallic acid / PEG-grafted graphene composite material prepared by S3 and 48 g of polyamide 6 (PA6) granules were melt-blended in an internal mixer at 180 rpm and 240°C for 30 min to prepare a masterbatch. The masterbatch was added to a plunger spinneret and melt-spun at 260°C through a spinneret with a diameter of 0.4 mm to obtain graphene-reinforced polyamide antibacterial composite fiber.

[0079] Comparative Example 4

[0080] The difference between this comparative example and Example 1 is that in step S2, the amount of amino-terminated polyethylene glycol is changed to 1.0 g.

[0081] Comparative Example 5

[0082] The difference between this comparative example and Example 1 is that in step S3, the amount of dopamine hydrochloride used is changed to 0.1 g.

[0083] Comparative Example 6

[0084] The difference between this comparative example and Example 1 is that in step S4, the amount of free dopamine hydrochloride is changed to 0.3 g.

[0085] Performance testing

[0086] The modified polyamide 6 prepared in Examples 1-2 and Comparative Examples 1-6 were subjected to the following tests:

[0087] Elongation at break: Tested according to ISO 527.

[0088] Tensile strength: Tested according to ISO 527.

[0089] Antibacterial properties: Tested in accordance with GB / T31402-2015.

[0090] The test results are shown in Table 1.

[0091] Table 1 Performance Test Results

[0092]

[0093] The excellent elongation at break, tensile strength, and antibacterial properties of Examples 1-2 indicate that the combined use of PEG grafting, gallic acid-dopamine covalent composite, and polydopamine modification within a specific dosage range can significantly improve the overall performance of the composite fiber.

[0094] Comparative Example 1 directly blends edge-carboxylated graphene with PA6. Lacking PEG flexible chains and an antibacterial functional layer, the graphene exhibits poor dispersibility and weak interfacial bonding. Relying solely on the intrinsic antibacterial properties of graphene, both mechanical properties and antibacterial activity are low.

[0095] Comparative Example 2, modified only with gallic acid, showed poor graphene dispersion, weak interfacial bonding, decreased antibacterial function, and decreased mechanical properties.

[0096] Comparative Example 3 was modified with only gallic acid and PEG, without the introduction of dopamine, lacking a polydopamine coating layer, and the gallic acid failed to anchor effectively, resulting in poor antibacterial durability. At the same time, the interface structure was imperfect and the mechanical properties were low.

[0097] In Comparative Example 4, the amount of PEG used in step S2 was too high, and the grafting density was too large, which hindered the effective encapsulation of GA-DA and PDA in the subsequent process. The disordered interface structure led to a decrease in both mechanical properties and antibacterial properties.

[0098] In Comparative Example 5, the amount of dopamine used in step S3 was too low, resulting in insufficient dopamine content in GA-DA, which could not be effectively embedded in the PDA layer, leading to easy loss of antibacterial function. At the same time, insufficient interfacial cross-linking resulted in poor mechanical properties.

[0099] In Comparative Example 6, the amount of free dopamine in step S4 was too high, the PDA layer was too thick, and the coating was excessive, which hindered the direct interfacial bonding between graphene and PA6, resulting in a significant decrease in mechanical properties and a slight reduction in antibacterial properties due to the excessive coating.

[0100] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing graphene-reinforced polyamide antibacterial composite fibers, characterized in that, Includes the following steps: S1. Preparation of edge-carboxylated graphene; S2. Disperse edge-carboxylated graphene in buffer solution, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and terminal amino polyethylene glycol, and react; after the reaction is complete, dialyze and freeze-dry to obtain PEG-grafted graphene. S3. Gallic acid was dissolved in anhydrous ethanol, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dopamine hydrochloride were added and reacted. After the reaction was completed, the mixture was rotary evaporated, deionized water was added, the pH was adjusted, the precipitate was precipitated, the precipitate was collected by centrifugation, washed with water, and dried under vacuum to obtain the gallic acid-dopamine amide complex. S4. Disperse PEG-grafted graphene in buffer solution, add gallic acid-dopamine amide complex, add dopamine hydrochloride, stir evenly, react, after the reaction is complete, centrifuge, collect the precipitate, wash, dry, and obtain GA-PEG-dopamine-G composite material. S5.GA-PEG-dopamine-G composite material and polyamide 6 granules were used to make a masterbatch; the masterbatch was melt-spun to obtain graphene-reinforced polyamide antibacterial composite fiber.

2. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 1, characterized in that, After ball milling graphene in a container containing dry ice, it was soaked in hydrochloric acid, filtered, washed, and freeze-dried to obtain edge-carboxylated graphene.

3. The method for preparing graphene-reinforced polyamide antibacterial composite fibers according to claim 2, characterized in that, The thickness of the graphene sheets is 0.5-5 nm.

4. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 2, characterized in that, The mass ratio of graphene to dry ice is 1:(10-30).

5. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 2, characterized in that, The mass concentration of the hydrochloric acid is 0.5-2 mol / L.

6. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 1, characterized in that, The mass ratio of edge-carboxylated graphene to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and terminal amino polyethylene glycol is 1:(0.4-0.5):(0.25-0.35):(0.4-0.6).

7. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 1, characterized in that, The mass ratio of gallic acid to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and dopamine hydrochloride is 1:(0.4-0.5):(0.25-0.35):(0.15-0.25).

8. The method for preparing graphene-reinforced polyamide antibacterial composite fiber according to claim 1, characterized in that, The mass ratio of PEG-grafted graphene to gallic acid-dopamine amide complex and dopamine hydrochloride is 1:(0.4-0.6):(0.05-0.15).

9. A polyamide antibacterial composite fiber prepared by the method for preparing graphene-reinforced polyamide antibacterial composite fiber according to any one of claims 1-9.

10. The application of a polyamide antibacterial composite fiber prepared by any one of claims 1-9 in the preparation of fibers.

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