ANF fibrous ion detector with coaxial three-layer structure and preparation method thereof

Abstract

The invention belongs to the field of ion detection, and discloses an ANF fibrous ion detector with a coaxial three-layer structure and a preparation method thereof.The preparation method comprises the steps that hydroxyapatite / ANF mixed liquor serves as outer-layer injection, pre-prepared mixed liquor A serves as inner-layer injection, and a coaxial wet spinning extrusion process is carried out in formic acid solution to obtain an ANF fibrous ion detector with a coaxial three-layer structure; the coaxial double-layer ANF-based hydrogel fiber is obtained; freezing and freeze-drying the coaxial double-layer ANF-based hydrogel fiber to obtain a hollow ANF-based fiber material; and then placing the obtained product in an ANF / DMSO dispersion liquid for dipping reaction, drying, and freeze-drying to obtain the ANF fibrous ion detector with a coaxial three-layer structure. The ANF / hydroxyapatite nanowire serves as the outer layer, the silver nanowire / MXene conductive material or the copper nanowire / MXene conductive material serves as the middle layer, the ANF network is loaded on the middle layer to serve as the core layer, and the detection efficiency and sensitivity of ions can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of ion detection technology, and specifically relates to an ANF fiber ion detector with a coaxial three-layer structure and its preparation method. Background Technology

[0002] Aramid nanofibers (ANFs) are high-performance materials with properties such as high strength, light weight, flexibility and corrosion resistance, which makes them widely used in the field of flexible sensing and detection devices. For example, aramid nanofibers are widely used as matrix materials in fields such as stress and strain monitoring, ion detection and temperature monitoring.

[0003] However, in practical applications of ANF-based flexible sensing and detection devices, since aramid nanofibers themselves are non-conductive materials, conductive one-dimensional materials such as silver nanowires or copper nanowires, or two-dimensional materials such as graphene or MXene, are usually added to endow them with sensing or detection functions. Currently, the traditional method is to combine aramid nanofibers with added conductive materials to form porous aerogel materials, and then further impregnate them in ion-containing solutions for ion detection. However, in the above applications, the insulating aramid nanofiber materials prevent ion migration, thus limiting the sensitivity and detection range of ANF-based flexible sensing and detection devices. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides an ANF fiber-like ion detector with a coaxial three-layer structure and its preparation method, in order to solve the technical problem that the insulating aramid nanofiber material will prevent ion migration in the practical application of ANF-based flexible sensing and detection devices, thereby limiting the sensitivity and detection range of ANF-based flexible sensing and detection devices.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for fabricating an ANF fiber-like ion detector with a coaxial three-layer structure, comprising: Using a hydroxyapatite / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, coaxial bilayer ANF-based hydrogel fibers were obtained by coaxial wet spinning extrusion in formic acid solution. The preparation process of the pre-prepared mixture A is as follows: the silver nanowire / DMSO dispersion or the copper nanowire / DMSO dispersion is mixed with the MXene / DMSO system and mechanically stirred. Hollow ANF-based fiber material was obtained by freezing and freeze-drying coaxial bilayer ANF-based hydrogel fibers. Hollow ANF-based fiber material was immersed in an ANF / DMSO dispersion for reaction, and then dried and freeze-dried to obtain an ANF fibrous ion detector with a coaxial three-layer structure.

[0006] Furthermore, the preparation process of the hydroxyapatite / ANF mixture is as follows: Hydroxyapatite nanowires were mixed with DMSO and ultrasonically dispersed to obtain a hydroxyapatite nanowire dispersion. The hydroxyapatite nanowire dispersion was mixed with the ANF / DMSO dispersion and stirred to obtain a hydroxyapatite / ANF mixture.

[0007] Furthermore, the mass ratio of the hydroxyapatite nanowire dispersion to the ANF / DMSO dispersion is (1-6):(30-80); the mass fraction of the hydroxyapatite nanowire dispersion is 20%-40%, and the mass fraction of the ANF / DMSO dispersion is 1%-2%.

[0008] Furthermore, in the pre-prepared mixture A, the mass ratio of the silver nanowire / DMSO dispersion to the MXene / DMSO system is (1-2):(1-2), the mass fraction of the silver nanowire / DMSO dispersion is 10%-20%, and the mass fraction of the MXene / DMSO system is 5%-10%.

[0009] Furthermore, in the pre-prepared mixture A, the mass ratio of copper nanowire / DMSO dispersion to MXene / DMSO system is (1-2):(1-2), the mass fraction of copper nanowire / DMSO dispersion is 10%-20%, and the mass fraction of MXene / DMSO system is 5%-10%.

[0010] Furthermore, using a hydroxyapatite / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the coaxial bilayer ANF-based hydrogel fiber is obtained through a coaxial wet spinning extrusion process in formic acid solution, as follows: A hydroxyapatite / ANF mixture was used as the outer layer injection solution, and a pre-prepared mixture A was used as the inner layer injection solution. The mixture was injected into a formic acid solution through a syringe connected to a double-layered coaxial needle and extruded to obtain a coaxial double-layered ANF-based hydrogel fiber. The injection speed of the double-layered coaxial needle was 1-10 m / s, and the mass fraction of the formic acid solution was 5%-20%.

[0011] Furthermore, the process of impregnating the hollow ANF-based fiber material in an ANF / DMSO dispersion is as follows: Hollow ANF-based fiber material is impregnated in an ANF / DMSO dispersion and reacted under vacuum conditions for 1-10 hours; wherein the vacuum degree is 0.01-0.1 MPa and the reaction temperature is 15-25℃.

[0012] Furthermore, the hollow ANF-based fiber material has an outer shell of hydroxyapatite nanowires / ANF, an inner layer of silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and a hollow core structure.

[0013] Furthermore, the outer layer of the ANF fibrous ion detector with a coaxial three-layer structure is ANF / hydroxyapatite nanowires, the middle layer is silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and the core layer is an ANF network; wherein, the ANF network is loaded on the middle layer.

[0014] This invention also provides an ANF fiber ion detector with a coaxial three-layer structure, prepared using the aforementioned method for fabricating the ANF fiber ion detector with a coaxial three-layer structure; wherein, the ANF fiber ion detector with a coaxial three-layer structure can be used for Na… + K + H + Cl - or OH - The detection process.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for preparing an ANF fibrous ion detector with a coaxial three-layer structure. A hydroxyapatite / ANF mixture is used as the outer layer injection solution, and a pre-prepared mixture A is used as the inner layer injection solution. Hollow ANF-based fiber materials are prepared using coaxial wet spinning technology. The hollow ANF-based fiber materials are then impregnated in an ANF / DMSO dispersion to obtain an ANF fibrous ion detector with a coaxial three-layer structure. This detector consists of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and a core layer of ANF network loaded on the middle layer. Nanowires, acting as the outer layer, provide mechanical protection and a flexible substrate for the ion detector. Using silver nanowires / MXene or copper nanowires / MXene as the middle layer, the ion content in the solution can be effectively detected, changing accordingly with increases and decreases in ion content. Attaching an ANF network to the conductive middle layer significantly enhances the stability of the silver nanowire / MXene or copper nanowire / MXene conductive materials, improving the cycle life of the ion detector. In this invention, by injecting ANF / hydroxyapatite nanowires into a formic acid solution, the protons in the formic acid solution can protonate the ANF in the ANF / hydroxyapatite nanowires, causing the -NH groups on the ANF to... 2- Upon gaining protons, -NH3 is formed, creating a hydrogen bond network between ANF nanowires and between ANF and hydroxyapatite nanowires, resulting in a dense insulating shell. Silver nanowire / MXene conductive material or copper nanowire / MXene conductive material located inside the insulating shell is adsorbed onto the shell after freeze-drying, forming a hollow ANF-based fiber material. The hollow structure of the ANF-based fiber material facilitates the penetration of ion-containing solutions into the inner side of the fiber, effectively improving ion detection efficiency and sensitivity. Furthermore, an impregnation reaction forms an ANF network structure on the inner surface of the silver nanowire / MXene or copper nanowire / MXene conductive material, thereby improving the stability of the conductive network and preventing material detachment during ion concentration detection. The ANF fiber-like ion detector with a coaxial three-layer structure prepared in this invention uses ANF / hydroxyapatite nanowires as the outer layer, silver nanowire / MXene or copper nanowire / MXene conductive material as the middle layer, and an ANF network loaded on the middle layer as the core layer, which can be used for Na+ detection. + K + H + Cl - OH -The material is capable of ion detection in an atmosphere of 0.01-2.0 mol / L and can be tested 500-2000 times. It also has self-supporting properties, with a tensile strength of 0.7-2.5 MPa and an elongation at break of 4%-20%.

[0016] The ANF fiber ion detector with a coaxial three-layer structure provided by the present invention possesses all the advantages of the above-mentioned preparation method of the ANF fiber ion detector with a coaxial three-layer structure. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional SEM image of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1; Figure 2 This is a partial cross-sectional SEM image of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1; Figure 3 This is a cross-sectional SEM image of the outer layer of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] This invention provides a method for preparing an ANF fibrous ion detector with a coaxial three-layer structure, characterized by comprising: using a hydroxyapatite / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, and obtaining coaxial bilayer ANF-based hydrogel fibers through a coaxial wet spinning extrusion process in formic acid solution; wherein, the preparation process of the pre-prepared mixture A is as follows: mixing a silver nanowire / DMSO dispersion or a copper nanowire / DMSO dispersion with an MXene / DMSO system and mechanically stirring; freezing and freeze-drying the coaxial bilayer ANF-based hydrogel fibers to obtain hollow ANF-based fiber material; immersing the hollow ANF-based fiber material in an ANF / DMSO dispersion for reaction, followed by drying and freeze-drying to obtain an ANF fibrous ion detector with a coaxial three-layer structure.

[0021] Specifically, the fabrication method of the ANF fiber-like ion detector with a coaxial three-layer structure includes the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 10-60 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 20%-40%.

[0022] Step 2: Add 1-6g of hydroxyapatite nanowire dispersion to 30-80g of ANF / DMSO dispersion with a mass fraction of 1%-2%, stir for 2-5 hours to obtain hydroxyapatite nanowire / ANF mixture.

[0023] Step 3: Mix 1-2g of 10%-20% silver nanowire / DMSO dispersion or copper nanowire / DMSO dispersion with 1-2g of 5%-10% MXene / DMSO system and stir mechanically for 5-60 minutes to obtain pre-prepared mixture A.

[0024] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, inject the mixture into a 5%-20% formic acid solution at a speed of 1-10 mm / s using a syringe connected to a coaxial needle with both layers, to obtain coaxial bilayer ANF-based hydrogel fibers; wherein, in the coaxial needle with both layers, the inner needle diameter is 0.1-1 mm and the outer needle size is 0.2-1.5 mm.

[0025] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fibers in a refrigerator (-15℃), cold well (-65℃), or liquid nitrogen (-196℃) for 20s-90min to obtain frozen ANF-based fibers.

[0026] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at a freeze-drying temperature of -20℃ to 20℃ for 2-48 hours to obtain hollow ANF-based fiber materials; wherein, the outer layer of the hollow ANF-based fiber material is hydroxyapatite nanowires / ANF-based shell, the inner layer is silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and the core layer is a hollow structure.

[0027] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 1-10 hours to obtain the reacted ANF-based fiber material; wherein the vacuum degree of the vacuum drying oven is 0.01-0.1 MPa, and the reaction temperature is 15-25℃.

[0028] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, replace the solvent in deionized water for 5-24 hours, and freeze it in a refrigerator (-15℃), cold well (-65℃), or liquid nitrogen (-196℃) for 30 seconds to 100 minutes to obtain frozen ANF-based fibers.

[0029] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at a temperature of -20℃ to 20℃ for 2-48 hours to obtain an ANF fibrous ion detector with a coaxial three-layer structure; wherein the outer layer of the ANF fibrous ion detector with a coaxial three-layer structure is ANF / hydroxyapatite nanowires, the middle layer is silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and the core layer is an ANF network; wherein the ANF network is loaded on the middle layer.

[0030] Preparation principle: In the above embodiments, by injecting the hydroxyapatite / ANF mixture into the formic acid solution, the -NH group on the ANF is... 2-Upon gaining protons, -NH3 is formed, creating a hydrogen bond network between ANF nanowires and between ANF and hydroxyapatite nanowires. This forms a stable outer layer structure, enabling the fibrous ion detector to achieve self-support without the need for an additional mechanical support shell. Secondly, coaxial bilayer ANF-based hydrogel fibers are obtained in formic acid solution using a coaxial wet spinning extrusion process. This allows silver nanowire / MXene conductive material or copper nanowire / MXene conductive material to be adsorbed within the ANF / hydroxyapatite nanowires as a middle layer, forming a hollow structure. This hollow structure facilitates the penetration of ion-containing solutions into the inner side of the fibers. This invention effectively improves detection efficiency and sensitivity. Secondly, by forming an ANF network structure on the inner surface of silver nanowire / MXene conductive material or copper nanowire / MXene conductive material through an impregnation reaction, the stability of the conductive network can be improved, thereby preventing the conductive material from falling off when detecting ion concentration. In this invention, a mechanically supported ANF / hydroxyapatite nanowire outer layer, a conductive sensing silver nanowire / MXene or copper nanowire / MXene middle layer, and an ANF inner layer network that prevents the conductive material from falling off are prepared by coaxial spinning combined with solution impregnation method, achieving the effect of high-efficiency ion detection and solving the shortcomings of insulating aramid in preventing ion migration.

[0031] This invention prepares an ANF fibrous ion detector with a coaxial three-layer structure. ANF / hydroxyapatite nanowires serve as the outer layer, providing mechanical protection and a flexible substrate for the ion detector. A silver nanowire / MXene or copper nanowire / MXene conductive material serves as the middle layer, effectively detecting ion content in solution, which changes accordingly with increasing and decreasing ion content. An ANF network is attached to the conductive middle layer, enhancing the stability of the silver nanowire / MXene or copper nanowire / MXene layer and improving the detector's cycle life. In this invention, ANF / hydroxyapatite nanowires are used as the outer layer, silver nanowire / MXene or copper nanowire / MXene conductive material as the middle layer, and an ANF network is loaded onto the middle layer to form an ANF fibrous ion detector with a coaxial three-layer structure, which can be used for Na+ ionization. + K + H + Cl - and OH - The material is capable of ion detection in an atmosphere of 0.01-2.0 mol / L and can be tested 500-2000 times. It also has self-supporting properties, with a tensile strength of 0.7-2.5 MPa and an elongation at break of 4%-20%.

[0032] The following specific embodiments further explain the preparation method of the ANF fiber ion detector with a coaxial three-layer structure provided by the present invention: Example 1 This embodiment 1 provides a method for preparing an ANF fiber ion detector with a coaxial three-layer structure, including the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 10 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 20%.

[0033] Step 2: Add 1g of hydroxyapatite nanowire dispersion to 30g of ANF / DMSO dispersion with a mass fraction of 1%, stir for 2h to obtain hydroxyapatite nanowire / ANF mixture.

[0034] Step 3: Mix 1g of 10% silver nanowire / DMSO dispersion with 1g of 5% MXene / DMSO system and stir mechanically for 5 minutes to obtain pre-prepared mixture A.

[0035] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the mixture is injected into a 5% formic acid solution at a speed of 1 mm / s using a syringe connected to a coaxial needle with both layers, to obtain coaxial bilayer ANF-based hydrogel fibers; wherein, the inner layer needle has a diameter of 0.1 mm and the outer layer needle has a size of 0.2 mm.

[0036] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fiber in a refrigerator (-15℃) for 90 minutes to obtain the frozen ANF-based fiber.

[0037] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at a freeze-drying temperature of -20℃ for 2 hours to obtain a hollow ANF-based fiber material with an outer layer of hydroxyapatite nanowires / ANF-based shell, an inner layer of silver nanowires / MXene conductive material, and a hollow core.

[0038] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 1 hour to obtain the reacted ANF-based fiber material; wherein, the vacuum degree of the vacuum drying oven is 0.1 MPa and the reaction temperature is 15℃.

[0039] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, replace the solvent in deionized water for 5 hours, and freeze it in a refrigerator (-15℃) for 100 minutes to obtain the frozen ANF-based fiber.

[0040] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at -20°C for 2 hours to obtain an ANF fiber-like ion detector with a coaxial three-layer structure, consisting of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material, and an ANF network loaded on the middle layer.

[0041] Performance test results explanation: The ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1 above was subjected to performance testing; specifically, the ion concentration was detected using an electrochemical workstation, and the mechanical properties of the material were measured using a universal tensile testing machine. Experimental results show that the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1 can be used for Na+ ionization. + The ion detection was performed in an atmosphere of 0.01-1.0 mol / L for 500 detections. Secondly, the ANF fibrous ion detector prepared in Example 1 has a self-supporting characteristic, with a tensile strength of 0.7 MPa and a tensile elongation of 14%.

[0042] The ANF fibrous ion detector with a coaxial three-layer structure prepared in Example 1 has an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material loaded inside the ANF / hydroxyapatite nanowires, and a core layer of ANF network loaded on the middle layer. When conductive Na... + When incorporated into the silver nanowire / MXene conductive network, it effectively increases the material's conductivity and reduces its resistance, thereby enabling the detection of Na. + The concentration.

[0043] As attached Figure 1 As shown, attached Figure 1 The attached image shows a cross-sectional SEM image of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1. Figure 1 As can be seen, the ANF fiber ion detector has a hollow structure, and the outer solid core is also divided into three layers: inner, middle, and outer. The hollow structure is conducive to ion transmission and improves ion detection efficiency.

[0044] As attached Figure 2 As shown, attached Figure 2 The attached image shows a partial cross-sectional SEM image of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1. Figure 2 As can be seen, the outer solid core is divided into three layers: inner, middle and outer. The outermost layer is an ANF / hydroxyapatite nanowire mechanical support layer, the middle layer is a silver nanowire / MXene conductive layer, and an ANF layer is wrapped on the inner surface to play a fixing role.

[0045] As attached Figure 3 As shown, attached Figure 3 The attached image shows a cross-sectional SEM image of the outer layer of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 1. Figure 3 As can be seen, the outer layer of ANF fiber is a hard ANF / hydroxyapatite nanowire shell formed by formic acid replacement. ANF and hydroxyapatite form a thin-layer structure and self-assemble under the action of hydrogen bonds, achieving the effect of mechanical support.

[0046] Example 2 This embodiment 2 provides a method for preparing an ANF fiber ion detector with a coaxial three-layer structure, including the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 60 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 40%.

[0047] Step 2: Add 6g of hydroxyapatite nanowire dispersion to 80g of ANF / DMSO dispersion with a mass fraction of 2%, stir for 5h to obtain hydroxyapatite nanowire / ANF mixture.

[0048] Step 3: Mix 2g of 20% copper nanowire / DMSO dispersion with 2g of 10% MXene / DMSO system and stir mechanically for 60min to obtain pre-prepared mixture A.

[0049] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the mixture is injected into a 20% formic acid solution at a speed of 10 mm / s using a syringe connected to a double-layered coaxial needle to obtain coaxial double-layered ANF-based hydrogel fibers. The inner layer needle has a diameter of 1 mm, and the outer layer needle has a size of 1.5 mm.

[0050] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fiber in liquid nitrogen (-196℃) for 20 s to obtain the frozen ANF-based fiber.

[0051] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at a freeze-drying temperature of 20°C for 48 hours to obtain a hollow ANF-based fiber material with an outer layer of hydroxyapatite nanowires / ANF-based shell, an inner layer of copper nanowires / MXene conductive material, and a hollow core structure.

[0052] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 10 hours to obtain the reacted ANF-based fiber material; wherein, the vacuum degree of the vacuum drying oven is 0.01 MPa and the reaction temperature is 25℃.

[0053] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, replace the solvent in deionized water for 24 hours, and freeze it in liquid nitrogen (-196℃) for 30 seconds to obtain the frozen ANF-based fiber.

[0054] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at 20°C for 48 hours to obtain an ANF fiber-like ion detector with a coaxial three-layer structure, consisting of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of copper nanowires / MXene conductive material, and an ANF network loaded on the middle layer.

[0055] Performance test results explanation: The performance of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 2 was tested. Specifically, the ion concentration was detected using an electrochemical workstation, and the mechanical properties of the material were measured using a universal tensile testing machine. The experimental results show that the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 2 can be used for K... + The ion detection was performed in an atmosphere of 0.02-2.0 mol / L for 2000 detections. The ANF fiber ion detector prepared in Example 2 has a self-supporting feature, with a tensile strength of 2.5 MPa and an elongation at break of 4%.

[0056] The ANF fibrous ion detector with a coaxial three-layer structure prepared in Example 2 has an outer layer of ANF / hydroxyapatite nanowires, a middle layer of copper nanowires / MXene conductive material loaded inside the ANF / hydroxyapatite nanowires, and an ANF network loaded on the middle layer as the core layer. When the conductive K... + When incorporated into the copper nanowire / MXene conductive network, it effectively increases the material's conductivity and reduces its resistance, thereby enabling the detection of K. + The concentration.

[0057] Example 3 This embodiment 3 provides a method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure, including the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 30 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 30%.

[0058] Step 2: Add 3g of hydroxyapatite nanowire dispersion to 50g of ANF / DMSO dispersion with a mass fraction of 1.5%, stir for 3h to obtain hydroxyapatite nanowire / ANF mixture.

[0059] Step 3: Mix 1.5g of 15% silver nanowire / DMSO dispersion with 1.5g of 8% MXene / DMSO system and stir mechanically for 30min to obtain pre-prepared mixture A.

[0060] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the mixture is injected into a 10% formic acid solution at a speed of 5 mm / s using a syringe connected to a coaxial needle with both layers, to obtain coaxial bilayer ANF-based hydrogel fibers; wherein, in the coaxial needle with both layers, the inner needle has a diameter of 0.5 mm and the outer needle has a size of 1.0 mm.

[0061] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fiber in a cold well (-65℃) for 50 minutes to obtain the frozen ANF-based fiber.

[0062] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at 0°C for 4 hours to obtain a hollow ANF-based fiber material with an outer layer of hydroxyapatite nanowires / ANF-based shell, an inner layer of silver nanowires / MXene conductive material, and a hollow core.

[0063] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 5 hours to obtain the reacted ANF-based fiber material; wherein, the vacuum degree of the vacuum drying oven is 0.05 MPa and the reaction temperature is 20℃.

[0064] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, replace the solvent in deionized water for 10 hours, and freeze it in a cold well (-65℃) for 60 minutes to obtain the frozen ANF-based fiber.

[0065] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at 0°C for 8 hours to obtain an ANF fiber-like ion detector with a coaxial three-layer structure, consisting of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material, and an ANF network loaded on the middle layer.

[0066] Performance test results explanation: The performance of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 3 was tested. Specifically, the ion concentration was detected using an electrochemical workstation, and the mechanical properties of the material were measured using a universal tensile testing machine. The experimental results show that the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 3 can be used for H... + The ion detection was performed in an atmosphere of 0.01-2.0 mol / L for 1000 detections. The ANF fiber ion detector prepared in Example 3 has a self-supporting feature, with a tensile strength of 1.1 MPa and a tensile elongation of 20%.

[0067] The ANF fibrous ion detector with a coaxial three-layer structure prepared in Example 3 has an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material loaded inside the ANF / hydroxyapatite nanowires, and an ANF network loaded on the middle layer as the core layer. When conductive H... + When incorporated into the silver nanowire / MXene conductive network, it effectively increases the material's conductivity and reduces its resistance, thereby enabling the detection of H. + The concentration.

[0068] Example 4 This embodiment 4 provides a method for preparing an ANF fiber ion detector with a coaxial three-layer structure, including the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 40 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 35%.

[0069] Step 2: Add 3.5g of hydroxyapatite nanowire dispersion to 60g of ANF / DMSO dispersion with a mass fraction of 1.7%, stir for 4h to obtain hydroxyapatite nanowire / ANF mixture.

[0070] Step 3: Mix 1.8g of 17% silver nanowire / DMSO dispersion with 1.6g of 9% MXene / DMSO system and stir mechanically for 50min to obtain pre-prepared mixture A.

[0071] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the mixture is injected into a 15% formic acid solution at a speed of 8 mm / s using a syringe connected to a coaxial needle with both layers, to obtain coaxial bilayer ANF-based hydrogel fibers; wherein, the inner layer needle has a diameter of 0.9 mm and the outer layer needle has a size of 1.4 mm.

[0072] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fiber in a cold well (-65℃) for 60 minutes to obtain the frozen ANF-based fiber.

[0073] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at a freeze-drying temperature of 10°C for 20 hours to obtain a hollow ANF-based fiber material with an outer layer of hydroxyapatite nanowires / ANF-based shell, an inner layer of silver nanowires / MXene conductive material, and a core layer of hollow structure.

[0074] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 9 hours to obtain the reacted ANF-based fiber material; wherein, the vacuum degree of the vacuum drying oven is 0.08 MPa and the reaction temperature is 23℃.

[0075] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, perform solvent replacement in deionized water for 20 hours, and freeze it in a cold well (-65℃) for 80 minutes to obtain frozen ANF-based fibers.

[0076] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at 10°C for 40 hours to obtain an ANF fiber-like ion detector with a coaxial three-layer structure, consisting of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material, and an ANF network loaded on the middle layer.

[0077] Performance test results explanation: The performance of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 4 was tested. Specifically, the ion concentration was detected using an electrochemical workstation, and the mechanical properties of the material were measured using a universal tensile testing machine. The experimental results show that the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 4 can be used for Cl... - The ion detection was performed in an atmosphere of 0.03-2.0 mol / L for 1500 detections. The ANF fiber ion detector prepared in Example 4 has a self-supporting feature, with a tensile strength of 2.0 MPa and an elongation at break of 17%.

[0078] The ANF fibrous ion detector with a coaxial three-layer structure prepared in Example 4 has an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material loaded inside the ANF / hydroxyapatite nanowires, and an ANF network loaded on the middle layer as the core layer. When conductive Cl... -When incorporated into the silver nanowire / MXene conductive network, it effectively increases the material's conductivity and reduces its resistance, thereby enabling the detection of Cl. - The concentration.

[0079] Example 5 This embodiment 5 provides a method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure, including the following steps: Step 1: Add solid hydroxyapatite nanowires to DMSO and ultrasonically disperse for 20 min to obtain a hydroxyapatite nanowire dispersion with a mass fraction of 25%.

[0080] Step 2: Add 2g of hydroxyapatite nanowire dispersion to 40g of ANF / DMSO dispersion with a mass fraction of 1.2%, stir for 2.5h to obtain hydroxyapatite nanowire / ANF mixture.

[0081] Step 3: Mix 1.1g of 11% silver nanowire / DMSO dispersion with 1.2g of 6% MXene / DMSO system and stir mechanically for 10min to obtain pre-prepared mixture A.

[0082] Step 4: Using a hydroxyapatite nanowire / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, the mixture is injected into a 7% formic acid solution at a speed of 3 mm / s using a syringe connected to a coaxial needle with both layers, to obtain coaxial bilayer ANF-based hydrogel fibers; wherein, the inner layer needle has a diameter of 0.4 mm and the outer layer needle has a size of 0.7 mm.

[0083] Step 5: Freeze the coaxial bilayer ANF-based hydrogel fiber in a refrigerator (-15℃) for 40 minutes to obtain the frozen ANF-based fiber.

[0084] Step 6: Freeze-dry the frozen ANF-based fibers in a freeze dryer at a freeze-drying temperature of -10℃ for 5 hours to obtain a hollow ANF-based fiber material with an outer layer of hydroxyapatite nanowires / ANF-based shell, an inner layer of silver nanowires / MXene conductive material, and a hollow core.

[0085] Step 7: Place the hollow ANF-based fiber material in an ANF / DMSO dispersion, and then let it stand in a vacuum drying oven for 3 hours to obtain the reacted ANF-based fiber material; wherein, the vacuum degree of the vacuum drying oven is 0.03 MPa and the reaction temperature is 17℃.

[0086] Step 8: Remove the reacted ANF-based fiber material from the ANF / DMSO dispersion, replace the solvent in deionized water for 7 hours, and freeze it in liquid nitrogen (-196℃) for 50 seconds to obtain the frozen ANF-based fiber.

[0087] Step 9: Place the frozen ANF-based fibers in a freeze dryer and freeze dry at -10℃ for 5 hours to obtain an ANF fiber-like ion detector with a coaxial three-layer structure, consisting of an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material, and an ANF network loaded on the middle layer.

[0088] Performance test results explanation: The performance of the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 5 was tested. Specifically, the ion concentration was detected using an electrochemical workstation, and the mechanical properties of the material were measured using a universal tensile testing machine. The experimental results show that the ANF fiber ion detector with a coaxial three-layer structure prepared in Example 5 can be used for OH... - The ion detection was performed in an atmosphere of 0.01-1.5 mol / L for 600 detections. The ANF fibrous ion detector prepared in Example 5 has a self-supporting feature, with a tensile strength of 0.8 MPa and an elongation at break of 8%.

[0089] The ANF fibrous ion detector with a coaxial three-layer structure prepared in Example 5 has an outer layer of ANF / hydroxyapatite nanowires, a middle layer of silver nanowires / MXene conductive material loaded inside the ANF / hydroxyapatite nanowires, and an ANF network loaded on the middle layer as the core layer. When conductive OH... - When incorporated into the silver nanowire / MXene conductive network, it effectively increases the material's conductivity and reduces its resistance, thereby enabling the detection of OH. - The concentration.

[0090] This invention provides a method for fabricating an ANF fibrous ion detector with a coaxial three-layer structure. ANF / hydroxyapatite nanowires serve as the outer layer, providing mechanical protection and a flexible substrate for the ion detector. A silver nanowire / MXene or copper nanowire / MXene conductive material serves as the middle layer, effectively detecting ion content in solution, which changes accordingly with increasing and decreasing ion content. An ANF network structure is attached to the conductive middle layer, enhancing the stability of the silver nanowire / MXene or copper nanowire / MXene layer and improving the detector's cycle life. Injecting ANF / hydroxyapatite nanowires into a formic acid solution creates a layer with -NH2 groups on the ANF. -Upon gaining a proton, -NH3 is formed, creating a hydrogen bond network between ANF nanowires and between ANF and hydroxyapatite nanowires, thus forming a dense insulating shell. The silver nanowires / MXene or copper nanowires / MXene inside the shell adsorb onto the shell after freeze-drying, forming a hollow structure. This hollow structure facilitates the penetration of ion-containing solutions into the inner side of the fibers, effectively improving detection efficiency and sensitivity. This invention can be used for Na… + K + H + Cl - OH - The material is capable of ion detection in an atmosphere of 0.01-2.0 mol / L and can be tested 500-2000 times. It also has self-supporting properties, with a tensile strength of 0.7-2.5 MPa and an elongation at break of 4%-20%.

[0091] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure, characterized in that, include: Using a hydroxyapatite / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution, coaxial bilayer ANF-based hydrogel fibers were obtained by coaxial wet spinning extrusion in formic acid solution. The preparation process of the pre-prepared mixture A is as follows: the silver nanowire / DMSO dispersion or the copper nanowire / DMSO dispersion is mixed with the MXene / DMSO system and mechanically stirred. Hollow ANF-based fiber material was obtained by freezing and freeze-drying coaxial bilayer ANF-based hydrogel fibers. Hollow ANF-based fiber material was immersed in an ANF / DMSO dispersion for reaction, and then dried and freeze-dried to obtain an ANF fibrous ion detector with a coaxial three-layer structure.

2. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, The preparation process of the hydroxyapatite / ANF mixture is as follows: Hydroxyapatite nanowires were mixed with DMSO and ultrasonically dispersed to obtain a hydroxyapatite nanowire dispersion. The hydroxyapatite nanowire dispersion was mixed with the ANF / DMSO dispersion and stirred to obtain a hydroxyapatite / ANF mixture.

3. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 2, characterized in that, The mass ratio of hydroxyapatite nanowire dispersion to ANF / DMSO dispersion is (1-6):(30-80); the mass fraction of hydroxyapatite nanowire dispersion is 20%-40%, and the mass fraction of ANF / DMSO dispersion is 1%-2%.

4. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, In the pre-prepared mixture A, the mass ratio of silver nanowire / DMSO dispersion to MXene / DMSO system is (1-2):(1-2), the mass fraction of silver nanowire / DMSO dispersion is 10%-20%, and the mass fraction of MXene / DMSO system is 5%-10%.

5. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, In the pre-prepared mixture A, the mass ratio of copper nanowire / DMSO dispersion to MXene / DMSO system is (1-2):(1-2), the mass fraction of copper nanowire / DMSO dispersion is 10%-20%, and the mass fraction of MXene / DMSO system is 5%-10%.

6. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, The process of obtaining coaxial bilayer ANF-based hydrogel fibers by using a hydroxyapatite / ANF mixture as the outer layer injection solution and a pre-prepared mixture A as the inner layer injection solution in formic acid solution via coaxial wet spinning extrusion is as follows: A hydroxyapatite / ANF mixture was used as the outer layer injection solution, and a pre-prepared mixture A was used as the inner layer injection solution. The mixture was injected into a formic acid solution through a syringe connected to a double-layered coaxial needle and extruded to obtain a coaxial double-layered ANF-based hydrogel fiber. The injection speed of the double-layered coaxial needle was 1-10 m / s, and the mass fraction of the formic acid solution was 5%-20%.

7. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, The process of impregnating hollow ANF-based fiber materials in an ANF / DMSO dispersion is as follows: Hollow ANF-based fiber material is impregnated in an ANF / DMSO dispersion and reacted under vacuum conditions for 1-10 hours; wherein the vacuum degree is 0.01-0.1 MPa and the reaction temperature is 15-25℃.

8. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, The hollow ANF-based fiber material has an outer shell of hydroxyapatite nanowires / ANF, an inner layer of silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and a hollow core.

9. The method for preparing an ANF fiber-like ion detector with a coaxial three-layer structure according to claim 1, characterized in that, The outer layer of the coaxial three-layer ANF fibrous ion detector is composed of ANF / hydroxyapatite nanowires, the middle layer is composed of silver nanowires / MXene conductive material or copper nanowires / MXene conductive material, and the core layer is an ANF network; wherein, the ANF network is loaded on the middle layer.

10. An ANF fiber-like ion detector with a coaxial three-layer structure, characterized in that, The ANF fiber-like ion detector with a coaxial three-layer structure was prepared using the method described in any one of claims 1-9; wherein the ANF fiber-like ion detector with a coaxial three-layer structure can be used for Na... + K + H + Cl - or OH - The detection process.

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