Durable conductive silk fabric and method of making the same

Abstract

The application discloses a preparation method of durable conductive silk fabric, comprising the following steps: pretreating silk fabric by using a formic acid aqueous solution to obtain pretreated silk fabric; preparing a polyphenol solution and immersing the pretreated silk in the polyphenol solution to obtain polyphenol modified silk fabric; respectively preparing a silver nitrate aqueous solution, a caffeic acid aqueous solution and a polyvinylpyrrolidone aqueous solution, mixing the three solutions uniformly, stirring and reacting at room temperature for 5-10 min, then increasing the temperature to 28-30 DEG C and standing for 3-5 h, filtering to obtain silver nanowires; preparing a polyethyleneimine aqueous solution, dispersing the silver nanowires in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion; immersing the polyphenol modified silk fabric in the silver nanowire / polyethyleneimine dispersion to treat, and repeating the immersion and curing to obtain silver nanowire / polyphenol / polyethyleneimine durable conductive silk fabric.

Description

Technical Field

[0001] This invention belongs to the field of functional finishing of textiles, and specifically relates to a method for preparing a durable conductive silk fabric and the durable conductive silk fabric prepared by the method. Background Technology

[0002] In recent years, flexible wearable devices have shown broad application prospects in personal motion monitoring, health care, and intelligent robotics. Conductive electronic textiles are currently the most researched category of flexible wearable devices. Compared with rigid wearable devices, electronic textiles are soft, comfortable, breathable, conform well to the human body, are lightweight and easy to carry, and are more human-friendly than other flexible wearable devices. Conductive fibers / fabrics are essential components in the preparation of electronic textiles. Typically, carbon-based materials (carbon nanotubes, graphene), conductive metal materials (gold, silver, copper), or conductive polymer materials (polythiophene, polypyrrole, polyaniline), or the more recent novel two-dimensional material Mxene, are modified onto the surface of textile materials or blended with spinning solutions to prepare conductive fibers / fabrics. Among these, conductive metal materials exhibit the best conductivity compared to the others, with silver nanomaterials being one of the most extensively studied.

[0003] Silk is a natural animal fiber with characteristics such as softness, strength, good luster, lightness, breathability, biodegradability, and good biocompatibility. With the development of science and technology, people have gained a deeper understanding of the structure and application of silk. Silk materials are gradually moving beyond the traditional textile field and demonstrating excellent potential application value in many fields such as biomedicine and flexible electronic devices.

[0004] Compared to conductive polymers and carbon materials, silver nanoparticles possess the advantages of being lightweight, having high electrical conductivity, and possessing antibacterial properties, leading to their widespread application in fields such as electronic skin, biomonitoring, human-computer interaction, and environmental monitoring. For example, silver nanoparticles were deposited on silk fabrics using an in-situ reduction method with silver ammonia solution to obtain silver nanoparticle / silk fabrics with long-lasting antibacterial properties (Journal of Textile Research, 2013, 34(8):5). Silver nanowires, compared to silver nanoparticles, have a high aspect ratio and better conductivity. For instance, Chinese invention patent CN202010518803.1 describes a polyaniline / silver nanowire cotton fiber flexible capacitor electrode material obtained through an impregnation method.

[0005] Traditional impregnation methods for preparing electronic textiles offer the advantage of simple operation, but the biggest problem currently lies in the poor wash resistance of the resulting composite electronic textiles. This is mainly because simple impregnation cannot improve the bonding strength between the conductive material and the textile substrate. To solve this problem, the introduction of adhesives is particularly important, but ensuring the flexibility and hand feel of the textile while improving the bonding strength is a challenge.

[0006] For example, Chinese invention patent CN201811280979.7 uses polydopamine and polyethyleneimine to modify the surface of a matrix material to obtain a modified matrix material. Then, metal-organic framework nanofibers are grown in situ on the surface of the modified matrix material and subjected to high-temperature carbonization treatment to obtain a highly conductive sensor material. However, this requires high-temperature carbonization treatment at 800℃~1200℃. Chinese invention patent CN202110038779.6 also carbonizes silk fabric to obtain conductive fibers, turning the original fibers into carbon fibers and losing some of the superior properties of the original fibers.

[0007] For example, Chinese invention patent CN202211114531.4 describes a process where a polyphenol / polyethyleneimine polymer is used as an adhesive layer on a textile substrate, and a metal coating is then prepared on the adhesive layer through chemical plating to obtain conductive fibers, thereby improving the adhesion between the fibers and metal particles. However, the formation of the coating and metal layer can affect the flexibility of the fibers or fabric. Furthermore, the chemical plating formula contains a relatively large number of chemical substances, which may affect the performance of silk fibers.

[0008] For example, Chinese invention patent CN202210553501.7 prepared silver nanowires for conductive finishing of cotton fabrics, resulting in cotton fabrics with lower resistance. Due to the naturally twisted structure of cotton fibers, which has large pores, silver nanowires are easily applied; however, even so, the wash fastness is still not very high. For silk fabrics, due to the smooth surface of silk and the lack of sufficient anchor points and pores, the wash fastness after conductive finishing is even more difficult to guarantee.

[0009] The above background information is provided only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0010] In view of this, in order to overcome the shortcomings of the prior art, the object of the present invention is to provide a method for preparing a durable conductive silk fabric based on polyethyleneimine.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A method for preparing a durable conductive silk fabric includes the following steps:

[0013] S1 uses formic acid aqueous solution to pretreat silk fabric. The treated silk fabric is first washed with sodium carbonate aqueous solution until neutral, then washed with water and dried to obtain pretreated silk fabric.

[0014] S2 prepares a polyphenol solution and immerses the pretreated silk in the polyphenol solution to obtain a polyphenol-modified silk fabric.

[0015] S3 Preparation of silver nanowires: Prepare aqueous solutions of silver nitrate, caffeic acid, and polyvinylpyrrolidone, respectively. Mix the three solutions evenly, stir at room temperature for 5-10 min, then heat to 28-30℃ and let stand for 3-5 h. Then filter to obtain silver nanowires.

[0016] S4 is used to prepare a polyethyleneimine aqueous solution, and the silver nanowires obtained in S3 are dispersed in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion.

[0017] S5 involves immersing the polyphenol-modified silk fabric obtained in S2 in a silver nanowire / polyethyleneimine dispersion for treatment, and repeating the immersion and curing process to obtain a durable conductive silk fabric made of silver nanowire / polyphenol / polyethyleneimine.

[0018] According to some preferred embodiments of the present invention, the volume fraction of the formic acid aqueous solution in S1 is 20% to 40%, and the pretreatment in S1 includes the following steps: treating the silk fabric with the formic acid aqueous solution at 15 to 55°C for 1 to 2 minutes.

[0019] According to some preferred embodiments of the present invention, the sodium carbonate aqueous solution in S1 has a mass percentage concentration of 0.1% to 1%, the drying temperature is 45 to 65°C, and the drying time is 50 to 70 min.

[0020] According to some preferred embodiments of the present invention, the polyphenolic substance in S2 is tannic acid and / or dopamine. The polyphenolic substance solution is formed by dissolving the polyphenolic substance in Tris hydrochloric acid buffer, and the concentration of the polyphenolic substance solution is 0.1 to 10 g / L.

[0021] According to some preferred embodiments of the present invention, the temperature of the treatment in S2 is 25-45°C and the time is 1-24h.

[0022] According to some preferred embodiments of the present invention, the concentration of the silver nitrate aqueous solution prepared in S3 is 0.5 to 3 mol / L, the concentration of the caffeic acid aqueous solution is 2 to 3 g / L, the concentration of the polyvinylpyrrolidone aqueous solution is 0.01 to 0.05 g / L, and the molecular weight of polyvinylpyrrolidone is 20,000 to 200,000 Daltons.

[0023] According to some preferred embodiments of the present invention, the polyethyleneimine in S4 has a molecular weight of 500 to 5000 Daltons and a concentration of 0.5 to 10 g / L; the concentration of silver nanowires in the silver nanowire / polyethyleneimine dispersion is 8-12 mg / mL.

[0024] According to some preferred embodiments of the present invention, in the treatment described in S5, the temperature of each immersion is 20-30°C, the time is 30-120 min, and the number of immersions is 2-5.

[0025] According to some preferred embodiments of the present invention, the curing temperature in S5 is 120-140°C and the curing time is 5-15 min.

[0026] The present invention also provides a durable conductive silk fabric prepared by any of the above-described preparation methods and its application in flexible devices such as flexible sensors.

[0027] The principle of this invention is as follows: After degumming, the surface of silk fibers is smooth, resulting in fewer pores within the fabric even when woven, making it difficult to directly attach conductive particles or fibers. To improve the reactivity of silk fabrics, this invention first treats the silk fabric with formic acid, allowing more active sites to form on the fabric surface. Then, by immersing the silk in a polyphenol solution, the active sites react with the polyphenol compounds, further increasing the number of active sites. Subsequently, this invention uses a polyvinylpyrrolidone template method, employing caffeic acid as a reducing agent, to synthesize highly conductive silver nanowires, rather than nanoparticles. The conductivity of the silver nanowires is significantly higher than that of silver nanoparticles. Furthermore, due to the use of caffeic acid as a reducing agent, the synthesized silver nanowires contain a higher concentration of caffeic acid on their surface, providing groups that further react with the active sites on the silk fiber surface. Simultaneously, to enhance the reaction between caffeic acid and polyphenols, this invention also adds polyethyleneimine as a crosslinking agent, promoting the true covalent grafting of silver nanowires onto the silk surface, constructing a conductive structure, and improving wash fastness. Because silk is relatively smooth, a single impregnation and curing process results in a small amount of liquid and insufficient conductivity. Therefore, multiple impregnations followed by drying and curing are necessary to improve the adhesion of silver nanowires to the silk surface.

[0028] Due to the adoption of the above technical solutions, this invention has the following advantages compared with the prior art: The method for preparing the durable conductive silk fabric of this invention produces a durable conductive silk fabric with good conductivity and excellent washability; it retains the flexibility and biocompatibility of silk, and can be used for human motion detection. Furthermore, the change in current is reproducible with repeated movements. Of course, it can also be fixed to a series of other body parts such as the elbow, wrist, knee, and ankle, serving as a flexible sensor for monitoring human motion. In addition, the silver nanowire / polyphenol / polyethyleneimine modified silk fabric obtained by this invention also has antibacterial properties, preventing bacterial contamination during sensor application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A photograph showing the silver nanowire / tannic acid / polyethyleneimine modified silk fabric prepared in Example 2 being connected to a circuit to make a small light bulb light up;

[0031] Figure 2 The images show the antibacterial effect of the silver nanowire / tannic acid / polyethyleneimine modified silk prepared in Example 3: (a) Staphylococcus aureus cultured in the solution without silver nanowire / tannic acid / polyethyleneimine modified silk; (b) Staphylococcus aureus cultured in the solution with silver nanowire / tannic acid / polyethyleneimine modified silk; (c) Escherichia coli cultured in the solution without silver nanowire / tannic acid / polyethyleneimine modified silk; and (d) Escherichia coli cultured in the solution with silver nanowire / tannic acid / polyethyleneimine modified silk.

[0032] Figure 3 The image shows the performance test results of the silver nanowire / dopamine / polyethyleneimine modified silk fabric prepared in Example 6, used for finger motion sensing. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 should fall within the scope of protection of the present invention.

[0034] The method for preparing the durable conductive silk fabric of the present invention includes the following steps:

[0035] (1) The silk fabric was pretreated with formic acid aqueous solution. The treated silk fabric was first washed with sodium carbonate aqueous solution until neutral, then washed with water and dried to obtain the pretreated silk fabric.

[0036] The specific steps are as follows: Treat the silk fabric with a 20%–40% (v / v) formic acid aqueous solution at 15–55℃ for 1–2 minutes. After treatment, wash the silk fabric with a 0.1%–1% (w / w) low-concentration sodium carbonate solution until neutral, then rinse with clean water and dry to obtain pretreated silk. This step roughens the surface of the silk fabric, providing more reaction sites. The drying temperature is 45–65℃, and the drying time is 50–70 minutes.

[0037] (2) Prepare a polyphenol solution and immerse the pretreated silk in the polyphenol solution to obtain a polyphenol-modified silk fabric.

[0038] The polyphenol solution was prepared by dissolving polyphenols in Tris hydrochloric acid buffer, with a concentration of 0.1–10 g / L. The treatment temperature was 25–45 °C, and the treatment time was 1–24 h. The polyphenols were tannic acid and / or dopamine.

[0039] (3) Preparation of silver nanowires

[0040] Prepare aqueous solutions of silver nitrate (0.5–3 mol / L), caffeic acid (2–3 g / L), and polyvinylpyrrolidone (0.01–0.05 g / L), respectively. Mix the three solutions thoroughly, stir at room temperature for 5–10 min, then heat to 28–30 °C and allow to stand for 3–5 h. Filter the mixture to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 20,000–200,000 Daltons.

[0041] (4) Prepare a 0.5-10 g / L polyethyleneimine aqueous solution, and disperse the silver nanowires obtained above in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion.

[0042] The molecular weight of polyethyleneimine is 500-5000 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 8-12 mg / mL.

[0043] (5) The polyphenol-modified silk fabric obtained above is immersed in silver nanowire / polyethyleneimine dispersion for treatment, and the immersion and curing are repeated to obtain silver nanowire / polyphenol / polyethyleneimine durable conductive silk fabric.

[0044] The temperature for each impregnation is 20–30℃, and the time is 30–120 min. The curing temperature is 120–140℃, and the curing time is 5–15 min.

[0045] Polyethyleneimine is an industrial polymer raw material with highly branched main chain and a large number of reactive groups (amine groups). It is widely used in papermaking, catalysis, flocculants, dye fixing agents, fiber modification, printing and dyeing auxiliaries, ion exchange resins and other fields, and has certain environmental friendliness.

[0046] Tannic acid is a natural substance found in plants, environmentally friendly, widely available, and pollution-free. It also possesses good biocompatibility and is essentially harmless to the human body. Its multifunctional groups, biocompatibility, and good adhesion make it particularly suitable for introduction into silk textiles. To further enhance the adhesive stability of tannic acid, polyethyleneimine can be introduced into the reaction system. The combination of polyethyleneimine and tannic acid, through the attraction of positive and negative charges, can further improve electrical conductivity. Simultaneously, it can also enhance positive charge, which is beneficial for the subsequent introduction of negatively charged silver nanowire networks.

[0047] Dopamine is a type of biomimetic adhesive, very similar to the mucinous protein component in mussel foot silk. The dopamine molecule has abundant catechol and amino functional groups, giving it universal adhesive properties and relatively safe and environmentally friendly characteristics, making it suitable for use in the impregnation process for functional textiles. However, the non-covalent interactions between dopamine molecules, or between polydopamine molecules after oxidative self-polymerization, remain relatively weak, making them prone to detachment at the interface. To address this, polyethyleneimine can be introduced into a compound to enhance the cross-linking between dopamine molecules. Dopamine and polyethyleneimine can undergo Shiff base or Michael addition reactions to form a stable cross-linked network. Therefore, dopamine / polyethyleneimine can be modified onto the surface of silk as an adhesive layer to prepare durable conductive silk fabrics.

[0048] Example 1

[0049] The method for preparing durable conductive silk fabric based on tannic acid in this embodiment specifically includes the following steps:

[0050] (1) Degummed silk was treated with 20% formic acid at 35℃ for 2 minutes. The treated silk was then washed with a 0.5% low-concentration sodium carbonate solution until neutral, and then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 55℃ and the drying time was 60 minutes.

[0051] (2) The pretreated silk fabric was immersed in a 0.2 g / L tannic acid solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 40 °C for 3 h to obtain tannic acid modified silk fabric.

[0052] (3) Prepare 1 mol / L silver nitrate aqueous solution, 2 g / L caffeic acid aqueous solution, and 0.02 g / L polyvinylpyrrolidone aqueous solution respectively. Mix the three solutions evenly, stir at room temperature for 8 min, then heat to 29℃ and let stand for 4 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 50,000 Daltons.

[0053] (4) Prepare a 0.7 g / L polyethyleneimine aqueous solution, and disperse the silver nanowires in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 1000 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 10 mg / mL.

[0054] (5) The tannic acid modified silk fabric was immersed in a silver nanowire / polyethyleneimine dispersion at 25°C for 90 min, followed by curing at 130°C for 10 min. The immersion and curing were repeated 3 times to obtain the silver nanowire / tannic acid / polyethyleneimine modified silk fabric.

[0055] In Example 1, the sheet resistance was measured after each curing cycle, and the results are shown in Table 1. After curing three times, the conductive silk fabric obtained was washed 50 times (10 standard soap wash cycles) according to the AATCC 61-2006 test standard for wash fastness, and the sheet resistance was measured again, and the results are shown in Table 2.

[0056] Example 2

[0057] The method for preparing durable conductive silk fabric based on tannic acid in this embodiment specifically includes the following steps:

[0058] (1) The silk was treated with 30% formic acid at 20℃ for 2 minutes. After treatment, the silk was first washed with a 0.2% low-concentration sodium carbonate solution until neutral, then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 60℃ and the drying time was 50 minutes.

[0059] (2) The pretreated silk fabric was immersed in a 0.5 g / L tannic acid solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 35°C for 6 h to obtain tannic acid modified silk fabric.

[0060] (3) Prepare 0.9 mol / L silver nitrate aqueous solution, 2.2 g / L caffeic acid aqueous solution, and 0.03 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions thoroughly, stir at room temperature for 10 min, then heat to 30℃ and let stand for 3 h. Filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 40,000 Daltons.

[0061] (4) Prepare a 1 g / L aqueous solution of polyethyleneimine, and disperse the silver nanowires in the aqueous solution of polyethyleneimine to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 600 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 11 mg / mL.

[0062] (5) The polyphenol-modified silk fabric was immersed in a silver nanowire / polyethyleneimine dispersion at 30°C for 30 min, followed by curing at 120°C for 15 min. The immersion and curing were repeated 3 times to obtain the silver nanowire / tannic acid / polyethyleneimine-modified silk fabric.

[0063] Figure 1 The image shows a small light bulb illuminating when the silver nanowire / tannic acid / polyethyleneimine modified silk fabric prepared in Example 2 is connected to a circuit. This indicates that the silver nanowire / tannic acid / polyethyleneimine modified silk fabric has excellent conductivity and can be used as a flexible electronic component connected to a circuit.

[0064] Example 3

[0065] The method for preparing durable conductive silk fabric based on tannic acid in this embodiment specifically includes the following steps:

[0066] (1) The silk was treated with 40% formic acid at 25°C for 1 min. The treated silk was then washed with a 0.7% low-concentration sodium carbonate solution until neutral, and then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 45°C and the drying time was 70 min.

[0067] (2) The pretreated silk fabric was immersed in a 1 g / L tannic acid solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 30°C for 8 h to obtain tannic acid modified silk fabric.

[0068] (3) Prepare 2 mol / L silver nitrate aqueous solution, 2.8 g / L caffeic acid aqueous solution, and 0.05 g / L polyvinylpyrrolidone aqueous solution respectively. Mix the three solutions evenly, stir at room temperature for 8 min, then heat to 28℃ and let stand for 5 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 100,000 Daltons.

[0069] (4) Prepare a 0.5 g / L polyethyleneimine aqueous solution, and disperse the silver nanowires in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 4000 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 12 mg / mL.

[0070] (5) The tannic acid modified silk fabric was immersed in a silver nanowire / polyethyleneimine dispersion with a concentration of 12 mg / mL at 20°C for 120 min, followed by curing at 140°C for 5 min. The immersion and curing were repeated 5 times to obtain the silver nanowire / tannic acid / polyethyleneimine modified silk fabric.

[0071] Example 4

[0072] The method for preparing the dopamine-based durable conductive silk fabric in this embodiment specifically includes the following steps:

[0073] (1) The silk was treated with 20% formic acid at 35°C for 2 min. After treatment, the silk was first washed with a 0.3% low-concentration sodium carbonate solution until neutral, then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 55°C and the drying time was 60 min.

[0074] (2) The silk fabric was immersed in a 5 g / L dopamine solution (using Tris hydrochloric acid buffer as solvent), the reaction temperature was 40℃, and the reaction time was 3 h to obtain dopamine modified silk fabric.

[0075] (3) Preparation of silver nanowires: Prepare 2.5 mol / L silver nitrate aqueous solution, 2.8 g / L caffeic acid aqueous solution, and 0.04 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions evenly, stir at room temperature for 6 min, then heat to 28℃ and let stand for 5 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 30,000 Daltons.

[0076] (4) Prepare an 8 g / L aqueous solution of polyethyleneimine, and disperse the silver nanowires obtained above in the aqueous solution of polyethyleneimine to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 1000 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 9 mg / mL.

[0077] (5) The dopamine-modified silk fabric was immersed in a silver nanowire / polyethyleneimine dispersion with a concentration of 9 mg / mL at 25°C for 90 min, followed by curing at 130°C for 15 min. The immersion and curing were repeated 3 times to obtain the silver nanowire / dopamine / polyethyleneimine modified silk fabric.

[0078] The sheet resistance was measured after each curing cycle, and the results are shown in Table 1. After curing three times, the conductive silk fabric was washed 50 times (10 standard soap wash cycles) according to the AATCC 61-2006 test standard for wash fastness, and the sheet resistance was measured again, and the results are shown in Table 2.

[0079] Example 5

[0080] The method for preparing the dopamine-based durable conductive silk fabric in this embodiment specifically includes the following steps:

[0081] (1) Degummed silk was treated with 30% formic acid at 20℃ for 2 minutes. The treated silk was then washed with a 0.5% low-concentration sodium carbonate solution until neutral, and then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 60℃ and the drying time was 50 minutes.

[0082] (2) The silk fabric was immersed in a 3 g / L dopamine solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 45°C for 2 h to obtain dopamine-modified silk fabric.

[0083] (3) Preparation of silver nanowires: Prepare 1.8 mol / L silver nitrate aqueous solution, 2.4 g / L caffeic acid aqueous solution, and 0.03 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions thoroughly, stir at room temperature for 8 min, then heat to 30℃ and let stand for 3 h. Filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 100,000 Daltons.

[0084] (4) Prepare a 5 g / L aqueous solution of polyethyleneimine, and disperse the silver nanowires obtained above in the aqueous solution of polyethyleneimine to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 800 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 10 mg / mL.

[0085] (5) The dopamine-modified silk fabric was immersed in a silver nanowire / polyethyleneimine dispersion with a concentration of 10 mg / mL at 30°C for 30 min, and then cured at 120°C for 15 min. The immersion and curing were repeated twice to obtain the silver nanowire / dopamine / polyethyleneimine modified silk fabric.

[0086] Example 6

[0087] The method for preparing the dopamine-based durable conductive silk fabric in this embodiment specifically includes the following steps:

[0088] (1) Degummed silk was treated with 40% formic acid at 25℃ for 1 min. The treated silk was then washed with a 0.6% low-concentration sodium carbonate solution until neutral, and then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 45℃ and the drying time was 70 min.

[0089] (2) The silk fabric was immersed in a 1 g / L dopamine solution (using Tris hydrochloric acid buffer as solvent), the reaction temperature was 30℃, and the reaction time was 1 h to obtain dopamine modified silk fabric.

[0090] (3) Preparation of silver nanowires: Prepare 2.8 mol / L silver nitrate aqueous solution, 2.7 g / L caffeic acid aqueous solution, and 0.04 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions thoroughly, stir at room temperature for 10 min, then heat to 30℃ and let stand for 3.5 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 100,000 Daltons.

[0091] (4) Prepare a 12 g / L polyethyleneimine aqueous solution and disperse the silver nanowires obtained above in the polyethyleneimine aqueous solution to obtain a silver nanowire / polyethyleneimine dispersion. The molecular weight of polyethyleneimine is 3000 Daltons, and the concentration of silver nanowires in the prepared silver nanowire / polyethyleneimine dispersion is 10 mg / mL.

[0092] (4) The dopamine-modified silk fabric was immersed in 3 mL of a 10 mg / mL silver nanowire / polyethyleneimine dispersion at room temperature (20°C) for 120 min, followed by curing at 140°C for 15 min. The immersion and curing were repeated 5 times to obtain the silver nanowire / dopamine / polyethyleneimine modified silk fabric.

[0093] Comparative Example 1

[0094] This comparative example was used to investigate the effect of not adding polyphenols / polyethyleneimine on the durability of conductive silk. The preparation of the silver nanowire modified silk fabric in this comparative example specifically included the following steps:

[0095] (1) Degummed silk was treated with 20% formic acid at 35℃ for 2 min. The treated silk was first washed with 0.2% low-concentration sodium carbonate solution until neutral, then washed with water and dried to obtain pretreated silk fabric. The drying temperature was 55℃ and the drying time was 60 min.

[0096] (2) Preparation of silver nanowires: Prepare 2 mol / L silver nitrate aqueous solution, 2 g / L caffeic acid aqueous solution, and 0.04 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions evenly, stir at room temperature for 10 min, then heat to 30℃ and let stand for 4 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 50,000 Daltons.

[0097] (3) The pretreated silk fabric was immersed in a silver nanowire dispersion with a concentration of 10 mg / mL at 25°C for 90 min, followed by curing at 130°C for 10 min. The immersion and curing were repeated 3 times to obtain the silver nanowire modified silk fabric. The silver nanowire dispersion was obtained by dispersing silver nanowires in water.

[0098] In step (3) of this comparative example, the sheet resistance value is measured after each curing. After curing three times, the conductive silk fabric obtained is washed 50 times (10 standard soap washing cycles) according to the AATCC 61-2006 test standard for wash fastness, and the sheet resistance is measured again. The results are shown in Table 2.

[0099] As shown in Table 2, the resistivity of silk treated only with silver nanowires, without tannic acid / polyethyleneimine treatment, decreased significantly after washing and quickly rose to 2.73 × 10⁻⁶. 5 Ω / sq.

[0100] Comparative Example 2

[0101] This comparative example was used to investigate the importance of adding polyethyleneimine to the durability of silver nanowire / tannic acid modified silk fabrics. The preparation of the silver nanowire / tannic acid modified silk fabric in this comparative example specifically included the following steps:

[0102] (1) Degummed silk was treated with 20% formic acid at 35℃ for 2 min. The treated silk was first washed with 0.5% low-concentration sodium carbonate solution until neutral, then washed with water and dried to obtain pretreated silk fabric. The drying temperature was 55℃ and the drying time was 60 min.

[0103] (2) The silk fabric was immersed in a 0.2 g / L tannic acid solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 40 °C for 3 h to obtain tannic acid modified silk fabric.

[0104] (3) Preparation of silver nanowires: Prepare 1 mol / L silver nitrate aqueous solution, 2 g / L caffeic acid aqueous solution, and 0.02 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions evenly, stir at room temperature for 8 min, then heat to 29℃ and let stand for 4 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 50,000 Daltons.

[0105] (4) The tannic acid-modified silk fabric was immersed in a silver nanowire dispersion with a concentration of 10 mg / mL at room temperature (25°C) for 90 min, followed by curing at 130°C for 10 min. The immersion and curing were repeated 3 times to obtain the silver nanowire / tannic acid-modified silk fabric. The silver nanowire dispersion was obtained by dispersing silver nanowires in water.

[0106] After the conductive silk fabric obtained after curing three times was measured for sheet resistance, it was washed 50 times (10 standard soap wash cycles) according to the AATCC 61-2006 test standard for wash fastness, and the sheet resistance was measured again. The results are shown in Table 2.

[0107] Table 2 shows that the silk treated with only tannic acid and silver nanowires, without the introduction of polyethyleneimine, exhibited a greater decrease in electrical resistance after washing than the silk treated with tannic acid / polyethyleneimine. The resistance test results before and after washing of the two comparative examples and Example 1 indicate that tannic acid / polyethyleneimine treatment significantly improves the durability of the silver nanowire conductive silk fabric.

[0108] Comparative Example 3

[0109] This comparative example was used to investigate the importance of polyethyleneimine addition to the durability of silver nanowire / dopamine-modified silk fabrics. The preparation of the silver nanowire / dopamine-modified silk fabric in this comparative example specifically included the following steps:

[0110] (1) The silk was treated with 20% formic acid at 35℃ for 2 minutes. After treatment, the silk was first washed with a 0.3% low-concentration sodium carbonate solution until neutral, then rinsed with water and dried to obtain pretreated silk fabric. This step can roughen the surface of the silk fabric and provide more reaction sites. The drying temperature was 55℃ and the drying time was 60 minutes.

[0111] (2) The silk fabric was immersed in a 5 g / L dopamine solution (using Tris hydrochloric acid buffer as solvent) at a reaction temperature of 40°C for 3 h to obtain dopamine-modified silk fabric.

[0112] (3) Preparation of silver nanowires: Prepare 2.5 mol / L silver nitrate aqueous solution, 2.8 g / L caffeic acid aqueous solution, and 0.04 g / L polyvinylpyrrolidone aqueous solution, respectively. Mix the three solutions evenly, stir at room temperature for 6 min, then heat to 28℃ and let stand for 5 h. Then filter to obtain silver nanowires. The molecular weight of polyvinylpyrrolidone is 50,000 Daltons.

[0113] (4) The dopamine-modified silk fabric was immersed in a silver nanowire dispersion with a concentration of 9 mg / mL at room temperature (25°C) for 90 min, followed by curing at 130°C for 15 min. The immersion and curing were repeated 3 times to obtain the silver nanowire / dopamine-modified silk fabric. The silver nanowire dispersion was obtained by dispersing silver nanowires in water.

[0114] After curing three times, the conductive silk fabric obtained was subjected to 50 washes (10 standard soap wash cycles) according to the AATCC 61-2006 test standard for wash fastness, and the sheet resistance was measured again. The results are shown in Table 2. In the table, "~" indicates approximate.

[0115] Table 1. Sheet resistance values ​​of modified silk fabrics from Examples 1 and 4 after being immersed in silver nanowire solution for different numbers of times and after 50 soap washes.

[0116]

[0117] As shown in Table 1, silk itself is non-conductive. Through the treatment of this invention, the sheet resistance of the obtained conductive silk fabric significantly decreases with increasing number of impregnations with the silver nanowire solution. The silver nanowire / tannic acid / polyethyleneimine modified silk fabric prepared in Example 1 exhibits good conductivity stability; after 50 washes, the sheet resistance only increases to 283.7 Ω / sq, demonstrating excellent wash resistance. Similarly, the silver nanowire / dopamine / polyethyleneimine modified silk fabric obtained in Example 4 shows a significant decrease in sheet resistance with increasing number of impregnations with the silver nanowire solution, ultimately achieving a sheet resistance of approximately 7.1 Ω / sq, which then tends to stabilize. Under the action of dopamine / polyethyleneimine, the silver nanowire / dopamine / polyethyleneimine modified silk fabric exhibits good conductivity stability; after prolonged washing, the sheet resistance only increases to 13.5 Ω / sq.

[0118] Table 2 Comparison of wash durability of conductive silk prepared in Examples 1, 4 and different comparative examples.

[0119]

[0120] Based on the results of Comparative Examples 1 and 2 in Table 2, it can be observed that the tannic acid / polyethyleneimine adhesion layer imparts excellent conductive stability to the conductive silk fabric. The polyethyleneimine component gives the silk fabric surface more positive charge, which allows negatively charged silver nanowires to easily deposit onto the silk surface in a short time through electrostatic adsorption, thus giving the silk surface a denser conductive network of silver nanowires. Tannic acid, as a modified intermediate layer, connects with the silk fabric through strong hydrogen bonds. Furthermore, it imparts more phenolic hydroxyl groups to the silk fabric surface, which can easily coordinate and complex with the silver nanowires, further ensuring the stable deposition of silver nanowires on the fabric surface. In addition, tannic acid and polyethyleneimine attract each other through electrostatic forces, improving the durability of the silver nanowire conductive silk fabric.

[0121] Based on the results of Comparative Examples 3 and 4 in Table 2, it can also be seen that dopamine / polyethyleneimine also imparts excellent conductive stability to conductive silk fabrics. Dopamine / polyethyleneimine gives the silk fabric surface more positive charge, which makes it easy for negatively charged silver nanowires to deposit onto the silk surface more readily and quickly through electrostatic adsorption, thus giving the silk surface a denser conductive network of silver nanowires. Furthermore, dopamine / polyethyleneimine imparts more phenolic hydroxyl and amino functional groups to the silk fabric surface, enabling them to complex with more silver nanowires. The stable deposition of silver nanowires on the fabric surface ultimately facilitates the preparation of durable silver nanowire conductive silk fabrics.

[0122] Figure 2 This image shows the antibacterial effect of silver nanowires / tannic acid / polyethyleneimine modified silk prepared in Example 3. Figure 2 As can be seen, the number of Staphylococcus aureus colonies cultured with the silver nanowire / tannic acid / polyethyleneimine modified silk solution (a) was approximately 105, while the number of Staphylococcus aureus colonies cultured with the silver nanowire / tannic acid / polyethyleneimine modified silk solution (b) was approximately 8. The number of Escherichia coli colonies cultured with the silver nanowire / tannic acid / polyethyleneimine modified silk solution (c) was approximately 92, while the number of Escherichia coli colonies cultured with the silver nanowire / tannic acid / polyethyleneimine modified silk solution (d) was approximately 24. The silver nanowire / tannic acid / polyethyleneimine modified silk solution achieved an inhibition rate of 92.38% against Staphylococcus aureus and 73.91% against Escherichia coli. These results indicate that the silver nanowire / tannic acid / polyethyleneimine modified silk solution, in addition to its excellent conductivity, also possesses good antibacterial properties, providing an antibacterial solution for demanding wearable designs.

[0123] Figure 3This image shows a performance test diagram of the silver nanowire / dopamine / polyethyleneimine modified silk fabric prepared in Example 6 used in a finger motion sensor. As described above, the silver nanowire / dopamine / polyethyleneimine modified silk can be used as a flexible electronic component integrated into a conductive path. When a certain mechanical force is applied to it to deform it, it can convert mechanical signals into electrical signals and feed them back, such as... Figure 3 As shown, when a constant voltage is applied, the silver nanowire / dopamine / polyethyleneimine modified silk adheres to the finger joint and can provide feedback on the significant real-time relative resistance change as the finger straightens / bends. This indicates that the modified silk fabric prepared in this invention can be used as a sensor for limb movements such as fingers.

[0124] This invention discloses a durable conductive silk fabric and its preparation method. To improve the bonding strength between silver nanowires and silk fabric, and to enhance the durability and wash resistance of the finished fabric, the silk fabric is treated with formic acid before impregnation with silver nanowires, and then modified with tannic acid solution or dopamine solution. Silver nanowires are prepared using polyphenols. Finally, the modified silk fabric is impregnated with a silver nanowire / polyethyleneimine dispersion to obtain a silver nanowire / polyphenol / polyethyleneimine modified silk fabric. The preparation method of this invention for durable conductive silk fabric is simple, has good conductivity, and excellent antibacterial properties. Compared with other impregnation methods for preparing conductive fibers / fabrics, it exhibits superior wash resistance. The prepared silver nanowire conductive silk is antibacterial and has good conductivity, making it suitable for flexible sensing. It has promising applications in flexible wearable fields such as human motion detection, electronic textiles, electrothermal textiles, and health monitoring.

[0125] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0126] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing a durable conductive silk fabric, characterized in that, Includes the following steps: Formic acid aqueous solution was used to pretreat the silk fabric. The treated silk fabric was first washed with sodium carbonate aqueous solution until neutral, then washed with water and dried to obtain the pretreated silk fabric. A polyphenol solution is prepared, and the pretreated silk is immersed in the polyphenol solution for treatment to obtain polyphenol-modified silk fabric; Prepare aqueous solutions of silver nitrate, caffeic acid, and polyvinylpyrrolidone, respectively. Mix the three solutions thoroughly, stir at room temperature for 5-10 minutes, then heat to 28-30°C and let stand for 3-5 hours. Filter to obtain silver nanowires. Prepare an aqueous solution of polyethyleneimine, and disperse the silver nanowires in the aqueous solution of polyethyleneimine to obtain a silver nanowire / polyethyleneimine dispersion; The polyphenol-modified silk fabric was immersed in the silver nanowire / polyethyleneimine dispersion for treatment, and the immersion and curing were repeated to obtain a durable conductive silk fabric of silver nanowire / polyphenol / polyethyleneimine. The polyphenolic substance is tannic acid and / or dopamine; the polyphenolic substance solution is formed by dissolving the polyphenolic substance in Tris hydrochloric acid buffer, and the concentration of the polyphenolic substance solution is 0.1-10 g / L; The curing temperature for each step is 120–140°C, and the curing time is 5–15 minutes. The molecular weight of the polyethyleneimine is 500 to 5000 Daltons.

2. The preparation method according to claim 1, characterized in that, The volume fraction of the formic acid aqueous solution is 20% to 40%; the pretreatment includes the following steps: treating the silk fabric with the formic acid aqueous solution at 15 to 55°C for 1 to 2 minutes.

3. The preparation method according to claim 1, characterized in that, The sodium carbonate aqueous solution has a mass percentage concentration of 0.1% to 1%; the drying temperature is 45 to 65°C, and the drying time is 50 to 70 minutes.

4. The preparation method according to claim 1, characterized in that, The pretreated silk is immersed in the polyphenol solution at a temperature of 25–45°C for 1–24 hours.

5. The preparation method according to claim 1, characterized in that, The concentration of the silver nitrate aqueous solution is 0.5–3 mol / L, the concentration of the caffeic acid aqueous solution is 2–3 g / L, the concentration of the polyvinylpyrrolidone aqueous solution is 0.01–0.05 g / L, and the molecular weight of the polyvinylpyrrolidone is 20,000–200,000 Daltons.

6. The preparation method according to claim 1, characterized in that, The concentration of the polyethyleneimine solution is 0.5–10 g / L; the concentration of silver nanowires in the silver nanowire / polyethyleneimine dispersion is 8–12 mg / mL.

7. The preparation method according to claim 1, characterized in that, When the polyphenol-modified silk fabric is immersed in the silver nanowire / polyethyleneimine dispersion, the immersion is repeated 2 to 5 times, the immersion temperature is 20 to 30°C, and the immersion time for each immersion is 30 to 120 minutes.

8. A durable conductive silk fabric prepared by the preparation method according to any one of claims 1-7.

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